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Issue: December 2011
December 2011 Articles:

Negligence and medical manslaughter: what a doctor needs to know in a brief tutorial
Author: J C Watts BSc MB ChB FRCA FFICM
Consultant in Critical Care Medicine East Lancashire Trust
Haslingdon Rd, Blackburn,
JAP 2011: 5: 160-165.


Non-invasive cardiac output monitoring using bio-reactance technology: a novel method of haemodynamic monitoring
Author: Dr. M. David Jayapal and Dr. Joanna F. Thirsk
Dept. of Anaesthetics & Critical Care, King’s College Hospital
Denmark Hill, London, United Kingdom
JAP 2011: 5: 166-169.


Ankle block under ultrasound guidance
Authors: Dr Rajib Dutta,1 Dr S Qureshi,2 Dr N Patel,3

1Specialist Registrar in Anaesthesia and Chronic pain, King’s College Hospital NHS Foundation Trust, Denmark Hill, London
2ST4 in Anaesthesia, King’s College Hospital
3ST3 in Anaesthesia, Bristol Royal Infirmary

JAP 2011: 5: 170-173.


CRITICAL CARE CHALLENGES: Management of unsurvivable diffuse axonal injury; identifying the potential heart beating organ donor
Author: Mark Snazelle11ST7 in Anaesthetics at Guy’s and St Thomas’ NHS Trust
JAP 2011: 5; 174-186.



Negligence and medical manslaughter: what a doctor needs to know in a brief tutorial
Author: J C Watts BSc MB ChB FRCA FFICM
Consultant in Critical Care Medicine East Lancashire Trust
Haslingdon Rd, Blackburn,
JAP 2011: 5: 160-165.

Introduction
Doctors have a duty to patients and the profession to ensure that their practice is up to date; and that they apply their knowledge and practical skills in the best interests of patients. They also have wider role in the allocation of resources, and in maintaining the integrity of clinical services1-2. The key paragraphs from the General Medical council with regards to these responsibilities is shown in Boxes 1 and 2.

There are many sanctions that a doctor can face should they fail to meet these obligations. Locally, the employer could subject them to internal disciplinary action which may result in a warning, or termination of employment. If appropriate, the case could be referred to the GMC, where, if found to have performed seriously below the standard of a competent practitioner, they could receive a Warning (which stays on the record for five years), restrictions on registration, or be erased from the Register.

Box 1. GMC guidance Good Medical Practice GMC 2006 http://www.gmc-uk.org/guidance/good_medical_practice.asp
6. If you have good reason to think that patient safety is or may be seriously compromised by inadequate premises, equipment or other resources, policies or systems, you should put the matter right if that is possible. In all other cases you should draw the matter to the attention of your employing or contracting body
17. You must make sure that all the staff for whom you are responsible, including locums and students, are properly supervised
43. You must protect patients from risk of harm posed by another colleague’s conduct, performance or health
48 You must be satisfied that when you are off duty suitable arrangements have been made for your patient’s medical care
54: Delegation involves asking a colleague to provide treatment or care on your behalf. Although you will not be accountable for the decisions and actions of those to whom you delegate, you will still be responsible for the overall management of the patient, and accountable for your decision to delegate. When you delegate care or treatment you must be satisfied that the person to whom you delegate has the qualifications, experience, knowledge and skills to provide the care or treatment involved
Finally, it is possible that, if the doctor’s actions have been severely negligent, and as a result someone has lost their life, they could be subject to the process of the criminal law. This article briefly discusses the concepts of negligence and manslaughter in the context of clinical and professional practice.

Negligence and the Professional
Regulator
Negligence is a clear legal concept which involves a chain of causation. The chain must establish that there was a duty of care, a breach of that care, and that “harm” resulted from that breach3. The whole chain of causation has to be intact for the doctor to be found negligent , and for appropriate damages to be awarded. However, it is possible that a doctor could have been proven responsible for a negligent act following due legal process, but that this negligence was not sufficient for the professional regulator to take disciplinary action, as outlined in the case Calhaem vs the GMC (2007)4. This ruling suggested that a single episode of negligence may not in itself be enough in itself to establish that the doctor’s fitness to practise is impaired, unless it was sufficiently serious in itself. The Judge stated:

“…. Mere negligence does not constitute “misconduct” within the meaning of section 35C(2)(a) of the Medical Act 1983. ….depending upon the circumstances, negligent acts or omissions which are particularly serious may amount to “misconduct”…..A single negligent act or omission is less likely to cross the threshold of “misconduct” than multiple acts or omissions……a single negligent act or omission, if particularly grave, could be characterised as “misconduct”…”

In addition, Cohen v the GMC 20085 suggested that although the doctor’s fitness to practise may have been impaired when a serious error occurred, the passage of time may have allowed the doctor to take action to correct the deficiencies in his or her practice, to the degree that their practice may not be judged to be currently impaired.

Therefore, a doctor could admit negligence during a civil case, but may not be subject to erasure from the register, or restrictions on their practice by the GMC. However, a doctor guilty of a series of errors, or who has been found to have been severely negligent is much more likely to face action on their registration

The Definition of Manslaughter
The standards established for proving manslaughter are defined within the Homicide Act 19576.

Crudely, “manslaughter” is a legal term implying the unplanned, or unintentional, killing of a human being. The level of culpability that needs to be proven is less than that needed to prove murder, and generally depends upon the mens rea of the accused (ie the state of mind).

Box 2. GMC guidance “Management for Doctors” 2006 http://www.gmc-uk.org/guidance/ethical_guidance/management_for_doctors.asp
4. You continue to have a duty of care for the safety and well-being of patients when you work as a manager. You remain accountable to the GMC for your decisions and actions even when a non-doctor could perform your management role
10. All practising doctors use resources and play a role in setting priorities, developing policies and making other management decisions. All doctors have an obligation therefore to work with both medical and non-medical managers in a productive way for the benefit of patients and the public
12. It is not possible to set out all the roles doctors take on as managers. If your role involves responsibilities covered in this booklet, you should do your best to make sure that:
  • systems are in place to enable high quality medical services to be provided
  • care is provided and supervised only by staff who have the appropriate skills (including communication skills), experience, training and qualifications
  • significant risks to patients, staff and the health of the wider community are identified, assessed and addressed to minimise risk, and that they are reported in line with local and national procedures
  • systems are in place to identify the educational and training needs of students and staff, including locums, so that the best use is made of the time and resources available for keeping knowledge and skills up to date
  • all decisions, working practices and the working environment are lawful, with particular regard to the law on employment, equal opportunities and health and safety
  • information and policies on clinical effectiveness and clinical governance 6 are publicised and implemented effectively.
14. You should make sure that the people you manage have appropriate supervision, whether through close personal supervision (for junior doctors, for example) or through a managed system with clear reporting structures.
22. At times you may not have the resources to provide the best treatment or care that all your patients need. At such times your decisions should be based on sound research information on efficiency and efficacy, and in line with your duties to protect life and health, to respect patients’ autonomy and to treat justly
In the case of manslaughter, this is basically that the intent to cause death, or circumstances in which death was likely to result, was absent. In the terms of the melodramatic legal definition, there was no malice aforethought.

Broadly, there are two types of manslaughter defined in British law: voluntary and involuntary.

Voluntary manslaughter occurs when an individual is killed during the commission of another criminal act where the intention may have been to harm, but not to kill. The defendant will often use the defence that they were provoked by the victim; that they were acting in self defence; or that the balance of their mind was disturbed at the time (e.g. by fear of being attacked themselves). The success of such a defence will often depend upon whether the defendant can be defined as a “reasonable man” under the law: that is, displaying a normal amount of self control, and not being intoxicated

Involuntary manslaughter occurs when it can be shown that the intention to do harm was absent, and can have several sub-definitions. Constructive manslaughter occurs when the defendant was intending to commit a crime, but not harm. This would include for example, committing a minor traffic offence, as a result of which a bystander dies. The act was “unlawful” but even though someone lost their life there was no intention to “harm”.

Gross or Criminally negligent manslaughter occurs when the death of the victim is the result of recklessness, or wilful negligence, by the defendant. That is, the defendant should have anticipated that death might have occurred and taken action to avoid the negligent act. This includes acts of omission when there was a duty of care owed to the victim. It is to this category of crime that the two types of manslaughter that a doctor could face during their medical career belong.

Manslaughter in Clinical Practice: “Medical manslaughter”
The term “medical manslaughter” is used to refer to a death which results from a medical error during the course of treatment.

Key “clinical manslaughter” cases are summarised in Box 3.

Box 3: Key cases in medical manslaughter7, 9
R v Bateman (1925 19 Cr App R 8)
Dr Bateman was a General Practitioner who attended a home delivery. Whilst removing the placenta, he inadvertently removed part of the uterus, but did not realise this immediately. The patient continued to bleed, but was not referred to hospital for a week. The patient died, and Bateman was tried for manslaughter. He was found guilty, on the grounds that had he acted sooner the patient would not have died. He had owed the patient a duty of care, had breached that duty, and as a result of the breach the patient had died
Bateman appealed and the conviction was quashed on the grounds that even if he had breached his duty of care to the patient, the breach in itself was not sufficient on its own to cause the death of the patient
R v Adomako [ 1995 ] 1 AC 171
Dr Adomoko was an anaesthetist who took over a case from a colleague. The endotracheal tube became disconnected, but he failed to detect the hypoxia until the patient arrested and died. He was found guilty of manslaughter on the grounds of “reckless negligence” to such a degree, that it became a criminal act
R v Bateman (1925) seems to be the first modern case in which the terms of “medical manslaughter” were established.

The initial conviction was heavily criticised as it appeared to rely on the evidence of an expert who strayed outside of his field of expertise7-8.

Research has shown that the number of “medical manslaughter” cases has increased steadily over the years. Only fourdoctors were charged with manslaughter in relation to their clinical work in the 70’s and 80’s, but 17 were charged during the 1990’s. Ten of these were eventually convicted, but the majority were successful in having their convictions quashed on appeal. Six were charged between 2000 and 2002, but only one of these was found guilty. In contrast, in 2001 only 40 of 278 defendants charged with non-medical manslaughter were acquitted.

It is much harder to prove medical manslaughter because it must be shown that it is the breach of duty of care that is directly and solely responsible for the death of the patient.

Although there has been an increasing trend over the last few years for medical staff to be charged with manslaughter when a patient has died, it is still a relatively unusual event. It usually relates to a loss of life in what are perceived to be preventable circumstances that must therefore have been someone’s fault. This may reflect the seriousness of the consequences rather than the magnitude of any series of errors that led to the tragic outcome; or perceived dissatisfaction with regulatory disciplinary measures for dealing with such matters10-11.

Box 4 outlines some recent well publicised medical manslaughter cases.

Box 4. Some recent manslaughter cases
R v Misra and Srivasta [2004] EWCA Crim 2375
R v Misra & Srivastava [2005] 1 Cr App R 328 Court of Appeal
The victim had undergone elective patella tendon surgery and developed a post operative infection. The two junior doctors involved both failed over a serious of time to recognise that the patient was developing a serious illness, and both failed to obtain senior advice. The patient died from septic shock
The doctors appealed but the conviction was upheld12, 13.
Wrong site operation
A patient died after two surgeons removed the wrong kidney during an operation. Subsequently charged with manslaughter, the prosecution was halted when the actual cause of the patient’s death could not be determined14.
NG tube misplacement
A doctor and two nurses were charged with manslaughter after an elderly ITU patient was fed down a misplaced naso-gastric tube and died. The case was abandoned before trial15.
Corporate Manslaughter
Doctors in management positions within the NHS may find themselves charged with corporate manslaughter. The legal position with regards to manslaughter in relation to an employer’s negligence is defined in the Corporate Manlaughter and Corporate Homicide Act 200728 OPSI 200716. Under the Act, the offence is defined as one in which an organisation and its officials have managed or organised activities which result in the death of a person due to a breach of a duty of care. The Act makes it clear that the organisation owes a duty of care both to its employees and members of the public. Relevant wording from the act is shown in Box 5.

Box 5. Relevent sections of the Corporate Manslaughter and Corporate Homicide act 2007
(1) An organisation to which this section applies is guilty of an offence if the way in which its activities are managed or organised-
(a) causes a person’s death, and
(b) amounts to a gross breach of a relevant duty of care owed by the organisation to the deceased.

4 (b) a breach of a duty of care by an organisation is a “gross” breach if the conduct alleged to amount to a breach of that duty falls far below what can reasonably be expected of the organisation in the circumstances;
(c) “senior management”, in relation to an organisation, means the persons who play significant roles in-
(i) the making of decisions about how the whole or a substantial part of its activities are to be managed or organised, or
(ii) the actual managing or organising of the whole or a substantial part of those activities.

Meaning of “relevant duty of care”
(1) A “relevant duty of care”, in relation to an organisation, means any of the following duties owed by it under the law of negligence—
(a) a duty owed to its employees or to other persons working for the organisation or performing services for it;
(b) a duty owed as occupier of premises;
(c) a duty owed in connection with—
(i) the supply by the organisation of goods or services (whether for consideration or not),
(ii) the carrying on by the organisation of any construction or maintenance operations,
(iii) the carrying on by the organisation of any other activity on a commercial basis, or
(iv) the use or keeping by the organisation of any plant, vehicle or other thing;
(d) a duty owed to a person who, by reason of being a person within subsection (2), is someone for whose safety the organisation is responsible.
To date there have not been many successful corporate manslaughter prosecutions in the UK, but those that have succeeded have been brought against smaller companies with a relatively “hands on” management structure17. The common themes from these cases have all been that either staff were permitted to perform tasks without adequate training, equipment or safety precautions; or that staff were permitted to work excessive hours. Many of the cases involve employees who fell from a height, or whom were killed by unsecured or unsafe equipment. Several relate to the deaths of trawler crews. Some relate to deaths of members of the public due to tired haulage drivers. Further details can be obtained from the website of the Centre for Corporate Accountability18. Sentences included fines and/or imprisonment.

Corporate manslaughter applies to the deaths of all of those to whom the organisation has a duty of care. In the case of an NHS Trust this would be staff, patients and members of the public. A Medical Manager could therefore be named in a Corporate Manslaughter prosecution if they were felt to be responsible for poor working conditions that contributed to a preventable death of anyone in relation to their services or facilities. Specifically, Medical Directors are part of the Trust Board, and share vicarious liability with the other members of that body, and could be held responsible in law (as well as by the GMC) for decisions made by that body to which they agreed. Clinical Directors, or other heads of departments, could be held responsible for the poor managerial processes within their departments should a death result.

The Medical Manager’s Dilemma
If poor administrative processes for which the doctor was wholly or partially responsible caused a death, it is possible that a manslaughter charge could result. This could apply equally the death of a patient due to the actions of a doctor who was permitted to become fatigued due to working long hours; or the death of a fatigued doctor who was permitted to work excessive hours (eg in a car accident on the way home). The main law that applies here is of course the European Working Time Directive19. It is therefore important that medical managers should apply the job planning and other managerial tools at their disposal to ensure that the EWTD is fully complied with.

However, a Medical manager must also ensure the integrity of their service, and the safety of the staff providing that service. Whilst the EWTD is a key consideration in this regard, the manner in which the EWTD has been implemented has been questioned. A recent Coroner inquest concluded that the poor level of medical cover out of hours, caused by the local implementation of shifts that satisfied the EWTD without making appropriate cover arrangements, had contributed to the death of two patients at the same hospital. The Chief Executive, the Medical Director and the Clinical Director were all summoned to give evidence, and were criticised20. In addition, the NPSA published an alert in relation to the distance that key personnel may be from the location of the emergency work that they provide. It recorded several cases in which the delay was detrimental to patient care21.

In another case, it was suggested that a consultant had failed to appropriately supervise a trainee anaesthetist, as a result of which the patient died22. In the latter case a Consultant anaesthetist delegated a simple emergency procedure to a trainee, and left the premises to go to a garage a small distance away to fill his care with petrol. The trainee experienced difficulty with the airway, and the patient died. The Sheriff concluded that if the consultant had been on site the patient’s death may have been prevented; but an internal enquiry concluded that he was near enough to respond appropriately had a request for assistance been made

The dilemma of the medical manager is therefore to maintain service integrity to ensure patient and staff safety whilst complying with the EWTD and other relevant legislation, in the face of limited resources. These cases suggest that availability, delegation and response times are also important considerations. A failure to satisfy any of these requirements that resulted in death could result in a manslaughter charge.

Apart from the Bristol Heart inquiry23,24, the GMC has not really had to address the position of doctors in management in relation to the adequacy of the service provided. The Chief Executive of the Trust was a Consultant Radiologist, who was still on the medical register. He had been made aware by a variety of mechanisms that there were specific concerns about a high mortality rate in relation to paediatric cardiac procedures. He was found guilty by the GMC for not acting to properly investigate the concerns, or to suspend surgery whilst such an investigation took place. The Court of Appeal ruled that it was not sufficient for the doctor to state that he was acting as an administrator, and not a doctor. There was a duty to ensure patient care was appropriate even if the doctor was not administering that care directly, and even if they were merely acting as a manager to other doctors who were delivering the care.

Such problems continue to occur. The Francis Report25 suggested that widespread management failings at the Mid Staffordshire Trust may have contributed to an excess number of patient deaths. One of the findings, for example, was that three consultants were doing the work of six in the A&E department. Specific criticism of both the Medical and Nursing Directors has been made. At the time of writing it has been reported that the GMC and the NMC are investigating clinical staff in relation to these conclusions26.

A recent inquest concluded that a GP locum from Germany, Dr Ubani, committed a series of errors whilst working for an out of hours service in the UK. Dr Ubani commenced work without adequate rest, and without an induction. His command of English was poor, and his understanding of British prescribing practise was also inadequate. One patient died from an overdose of diamorphine. Whilst Dr Ubani was responsible for his own decisions and actions, it seems that a series of management failures failed to put in place appropriate checks and balances to maintain patient safety. Certainly it appears no attempt was made to ensure that he was not impaired by fatigue. The relatives of a patient who died are thought to be considering civil manslaughter actions against the employing PCT and its officials27, 28.

Conclusion
Whilst a rare occurrence, it is possible that doctors may find themselves accused of medical manslaughter. The legal process is clumsy and long, and so it may be that local and professional regulatory process will have to evolve to take timely and appropriate action in such cases, as prosecution for manslaughter in clinical circumstances is unlikely to achieve a satisfactory conclusion for relatives, individual doctors or the profession unless the grossest negligence is the cause

This does not belie the personal and professional stress that results from the investigation and any legal proceedings. Even if a prosecution is unsuccessful, it is possible that the doctor will still face disciplinary sanction from the GMC if severe negligence is proven. Medical managers may be in a more vulnerable position than their clinical colleagues because of the larger range of responsibilities they have.

References
  1. GMC guidance Good medical practice GMC 2006 http://www.gmc-uk.org/guidance/good_medical_practice.asp (accessed 31/5/2011)
  2. GMC guidance “Management for Doctors” 2006 http://www.gmc-uk.org/guidance/ethical_guidance/management_for_doctors.asp (accessed 31/5/2011)
  3. http://legal-dictionary.thefreedictionary.com/negligence
  4. Calhaem -v- General Medical Council. [2007] All ER (D) 300
  5. Cohen v General Medical Council [2008] All ER 307
  6. The Homicide Act 1957 (5 & 6 Eliz.2 c.11)
  7. R v Bateman (1925 19 Cr App R8)
  8. Broadhurst HC report of the trial of Rex vs Bateman BMJ . P49 BMJ Jan 3 1925 http://www.bmj.com/content/1/3340/49.2.full.pdf?sid=ff53b5b6-bf07-49db-91b4-d7b6db42ef41 (accessed 25/4/2011)
  9. R v Adomako [1995] AC 171. 30 June 1994
  10. Dyer C Doctors face trial for manslaughter as criminal charges against doctors continue to rise BMJ 325 : 63 doi: 10.1136/bmj.325.7355.63 (Published 13 July 2002) http://www.bmj.com/content/325/7355/63.1.full?sid=ff53b5b6-bf07-49db-91b4-d7b6db42ef41) (accessed 24/4/2011)
  11. Ferner RE McDowell SE Doctors charged with manslaughter in the course of medical practice. 1795-2005: a literature review J R Soc Med 2006 99(6) 309-314
  12. R v Misra and Srivasta [2004] EWCA Crim 2375
  13. R v Misra & Srivastava [2005] 1 Cr App R 328 Court of Appeal
  14. Dyer C Surgeons cleared of manslaughter after removing wrong kidney BMJ 2002;325:9 (Published 6 July 2002) 14,15
  15. Kennedy T “Cumbrian OAP died after feeding tube inserted into lungs - inquest” News & Star 5/6/10 http://www.newsandstar.co.uk/news/doctor-and-2-nurses-quizzed-over-death-1.716902?referrerPath=/news_round-up_1_96082 (accessed 20/4/11)
  16. Corporate Manlaughter and Corporate Homicide Act 2007 (28)OPSI 2007
  17. Welham M Corporate Manslaughter: The UK Draft Bill 2005 http://www.sheilapantry.com/cis/cis200505.html#FOCUS (accessed 18/4/11)
  18. Centre for Corporate Acountibility http://www.corporateaccountability.org/manslaughter/cases/main.htm 2 (accessed 20/3/11)
  19. European Council Directive 93/104/EC 23/11/93 http://www.eu-working-directive.co.uk/directives/1993-working-time-directive.htm (last accessed 24/2/10)
  20. Savill R “Coroner criticises EU working time directive after hearing of doctor shortage” 10/9/10http://www.telegraph.co.uk/health/healthnews/7995374/Coroner-criticises-EU-working-time-directive-after-hearing-of-doctor-shortage.html (accessed 21/3/11)
  21. NPSA Distance to travel for key on-call staff NPSA 27/11/09 http://www.nrls.npsa.nhs.uk/resources/?EntryId45=65334 (accessed 1/2/11)
  22. Williams W 15/9/04 “Doctor who left theatre to buy petrol is cleared Woman died during surgery” Scottish herald 15/9/04 http://www.heraldscotland.com/sport/spl/aberdeen/doctor-who-left-theatre-to-buy-petrol-is-cleared-woman-died-during-surgery-1.75571 (accessed 31/1/11)
  23. The Bristol Royal Infirmary Inquiry An inquiry into the management of care of children receiving complex heart surgery at the Bristol Royal Infirmary (2001) http://www.bristol-inquiry.org.uk/ (accessed 27/1/11)
  24. Roylance v GMC [2000] 1 AC 311
  25. The Mid staffordhireNHS Foundation trust Inquiry Independent Inquiry into care provided by Mid Staffordshire NHS Foundation Trust January 2005 – March 2009 2009 http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/@ps/documents/digitalasset/dh_113068.pdf (accessed 27/12/2010)
  26. Schlesinger F Declan A Shipman T “Up to 1,200 needless deaths, patients abused, staff bullied to meet targets... yet a secret inquiry into failing hospital says no one’s to blame” 25/2/10 http://www.dailymail.co.uk/news/article-1253438/Mid-Staffordshire-NHS-hospital-routinely-neglected-patients.html
  27. The Telegraph “Dr Daniel Ubani inquest: widow Iris Edwards died after visit from doctor” http://www.telegraph.co.uk/health/healthnews/7161561/Dr-Daniel-Ubani-inquest-widow-Iris-Edwards-died-after-visit-from-doctor.html
  28. The Telegraph “Daniel Ubani inquest: NHS failings allowed killer doctor to work” (published 5/2/10)http://www.telegraph.co.uk/health/healthnews/7161266/Daniel-Ubani-inquest-NHS-failings-allowed-killer-doctor-to-work.html

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Anaesthesia Product News please email us at editor@apnews.co.uk
Non-invasive cardiac output monitoring using bio-reactance technology: a novel method of haemodynamic monitoring
Author: Dr. M. David Jayapal and Dr. Joanna F. Thirsk
Dept. of Anaesthetics & Critical Care, King’s College Hospital
Denmark Hill, London, United Kingdom
JAP 2011: 5: 166-169.

Introduction
Monitoring oxygen delivery using monitors of blood flow has become a standard of care in critical illness. Multiple medical devices are available that provide information regarding static measures of indices such as cardiac index or more dynamic measures such as stroke volume variation. These monitors enable clinicians to predict fluid responsiveness and optimise the ratio of fluid resuscitation to use of vasopressors/inotropes in patients who have circulatory failure.

Although the pulmonary artery catheter has historically provided the most reliable flow data through the use of thermodilution derived cardiac output in conjunction with direct measurement of pulmonary artery occlusion pressure, the literature does not show a positive effect on patient outcome with PAC use1-3.

There are now a variety of alternative monitoring devices which claim to provide equivalent clinical data using less invasive technology with consequently less clinical risk. However, there are very few monitors of flow that are truly non-invasive. In this narrative review we describe one such device, the Non Invasive Cardiac Output Monitor (NICOM - Cheetah Medical), and compare it with other minimally invasive and non-invasive options.

How NICOM works
Thoracic bioimpedance was the first non-invasive method developed for cardiac output monitoring4-6. Bioimpedance allows intrabeat measurement of changes in transthoracic voltage amplitude in response to an injected high frequency current. However, its inherently low signal-to-noise ratio contributes to inaccuracy due to common electrical interferences and therefore greatly limits its clinical application.

Bioreactance is a new and unique technology which utilises frequency, not impedance, but shares some similarities and builds on experience with bioimpedance. The NICOM measures the change in the phase shift between an injected current and the measured voltage (dº). The change of dº over time, or dº/dt, is proportional to the change in flow brought about by cardiac ejection. Hence, stroke volume is directly correlated to dº/dt and to ventricular ejection time.

This concept is parallel to that of bioimpedance, however the move from measuring dZ/dt (impedance changes over time) to dº/dt (phase shifts over time) is a significant leap forward. This new approach is inherently more sensitive, less subject to ambient electrical noise and more flexible with patient movement, positioning and body habitus.

The NICOM system is comprised of a high frequency (75 KHz) sine wave generator and four dual electrode stickers that are used to establish electrical contact with the body. Within each sticker, one electrode is driven by an electric generator to inject the high frequency sine wave current into the body, while the other electrode is used by a voltage input amplifier. Signals are applied to and recorded from the left and right sides of the thorax. These signals are received separately and combined electrically before digital processing.

A continuous signal is provided which is averaged every 30 seconds to 1 minute to provide a very responsive measurement of cardiac output. Of note, because frequency has nothing to do with the location of the stickers or with body habitus, there is considerable flexibility in placement of the NICOM stickers. The NICOM electrode stickers can be applied in various places on the thorax as well as on the patient’s back with no impact on cardiac output readings and can be used equally well in lean or obese patients.

The following key parameters are measured:
  • Stroke volume (variation and Index)
  • Heart rate
  • Cardiac output and index
  • Non invasive blood pressure
  • Mean arterial pressure
  • Total peripheral resistance and index
  • Thoracic fluid content
  • Tissue oxygenation
Comparison of currently available minimally invasive and noninvasive haemodynamic monitoring
Currently available noninvasive methods include Bioimpedance, Bioreactance, Transthoracic Doppler, Transthoracic Echo and Sphygmomanometry (finger cuff) and minimally invasive methods include Transesophageal Doppler, Transesophageal Echo and Intratracheal partial CO2 rebreathing systems. They are compared in Table 1.

Figure 1: Graph demonstrating the difference between bioimpedance and bioreactance technology. (Courtesy Cheetah Medical)
Key Validation Studies of Bioreactance Technology
Studies have detailed the underlying principles and basic validation of bioreactance technology both in preclinical and clinical studies14. Here, we will mention the key validating studies assessing how NICOM lives up to its invasive competitors in the clinical arena.

In a prospective study by Squara et al8 cardiac output measurements obtained from bioreactance and continuous thermodilution were simultaneously recorded every minute and compared in 110 adult patients following cardiac surgery.

The study concluded that cardiac output measured by bioreactance produced acceptable accuracy, precision, and responsiveness. Cardiac output from the NICOM was shown to correlate with cardiac output values from continuous thermodilution with a correlation coefficient of 0.82 and bias of 0.18 l/minute.

Relative to continous thermodilution, NICOM had >90% sensitivity and specificity for detecting clinically relevant changes in cardiac output from a baseline value. Responsiveness during haemodynamic changes was faster when using the NICOM and precision was also better. Problems with the study were that it involved only one clinical setting i.e. post cardiac surgery, in patients who were mostly sedated +/- intubated.

NICOM was later evaluated in a multicentre evaluation involving five centres and 111 patients12. This study included critically ill patients, both medical and post-cardiac surgical, as well as patients from cardiac care units and cardiac catheterisation laboratories.

Unlike the previous study, those in the cardiac and medical care units were all awake with unrestricted movement. For the studies performed on patients in an intensive care unit, continuous cardiac output monitoring was performed using a pulmonary artery catheter connected to a Vigilance monitor (Edwards Life Sciences, Irvine, CA). For studies in the intensive care units, thermodilution and NICOM were highly correlated (r = 0.78, P< 0.0001) and did not differ significantly from each other (P = 0.55). This is the only study to date validating the NICOM in patients from a critical care environment.

Various other studies have been published comparing the NICOM with other thermodilution and arterial pulse contour devices (PiCCO, Flotrac-Vigileo)15, 16. Criteria for comparison were accuracy, precision, good responsiveness and reliable detection of directional changes in cardiac output.

A study by Marque et al comparing the NICOM with a pulse wave contour-based system (Flotrac-Vigileo) showed similar monitoring capabilities in post-operative cardiac surgery patients15. A study published shortly thereafter tested the cardiac output and stroke volume monitoring capabilities of NICOM compared to pulse contour analysis (PICCO- PC) calibrated by transpulmonary thermodilution (PICCO-TD). The study population consisted of 20 post-operative cardiac surgery patients and showed comparable monitoring capabilities of these parameters16.

Current and potential applications of NICOM
It is widely appreciated that there are many clinical settings in which it is desirable, and even clinically necessary, to measure and follow cardiac output. Although cardiac output monitoring is predominantly, and almost exclusively used in the critical care unit or operating room; there is increasing evidence that cardiac output should be determined and optimised as early as possible in the haemodynamically compromised even before admission to these areas

Figure 2: Electrode Placement (Courtesy Cheetah Medical)
This was highlighted in the landmark paper by Rivers et al17. Bioimpedance has little place in the critically ill population. The newer technology of bioreactance shows promise for use in the ITU as well as the perioperative setting. As a result of its non-invasiveness and ease of use, it is also ideal for use in the ward or the emergency department for the initial assessment of haemodynamic parameters in order to confirm a preliminary diagnosis and to assess response and guide initial treatment and fluid optimisation, from severe trauma to cardiogenic shock.

Other areas of potential use for the NICOM monitor include the preoperative assessment clinic, post-anaesthesia care unit, the arena of pre-hospital care, the pacemaker clinic for use in cardiac resynchronisation optimisation as well as within the community for management of heart failure and for renal dialysis monitoring.

Peri-operative use
There is considerable evidence to demonstrate the benefits of augmenting oxygen delivery in high-risk surgical patients during the peri-operative period18. Despite a general lack of implementation, goal-directed therapy (GDT) in selected patients using blood flow monitoring to achieve supranormal oxygen delivery targets to increase tissue perfusion and oxygenation decreases morbidity and mortality19. Furthermore, it has also been shown that starting GDT at any time during the peri-operative period has benefit.

A randomised control trial allocated high risk post operative general surgical patients to receive either post-operative GDT, targeting oxygen delivery of 600mls/min/m2, or conventional treatment. The median duration of hospital stay in the GDT group was significantly reduced (11 days (IQR 7 to 15) versus

14 days (IQR 11 to 27); p = 0.001)20. Post-operative GDT is associated with reductions in post-operative complications and duration of hospital stay.

Trauma/prehospital
Increased cardiac index, oxygen delivery index, and oxygen consumption in survivors of severe trauma have survival value. Augmentation of these values through goal-directed therapy compared to conventional therapy has shown decreased mortality21. The importance of non-invasive cardiac output monitoring in this arena is yet to be fully elucidated, but in line with this last point, the non-invasiveness of this method allows care to take place out of the critical care setting and at an earlier stage of resuscitation; even possibly within the pre-hospital environment, the ultimate goal being to increase efficiency of care.

Fluid optimisation (and drug titration)
In a prospective, two-centre study by Benomar et al, 75 consecutive intensive care unit adult patients were included in the study population immediately after cardiac surgery. NICOM was used to continuously record cardiac output at baseline, during a passive leg raising test, and then during a 500ml intravenous rapid colloid infusion. The change in cardiac output following fluid bolus was highly correlated with the change in cardiac output following passive leg raising22.

Emergency Room (non-traumatic)
Apart from its role in evaluating established heart failure, NICOM may well aid in the differential diagnosis of shortness of breath, a common emergency room presentation where differentiation between exacerbations of chronic pulmonary disease and acute heart failure may be difficult. In a recent study, it was found that the system, through dynamic measurements of cardiac output, may be used to differentiate between volume overload and disease escalation in cases of acute heart failure23. Its use in GDT for septic patients is another clear subgroup of patients who would derive benefit24.

Figure 3: NICOM monitor displaying real time values. Trend views, displayed graphically or numerically listed, can also be shown. (Courtesy Cheetah Medical)
Management of chronic heart failure
Cardiopulmonary exercise testing (CPX) is widely used to evaluate heart failure patients. Maximal oxygen uptake (pVO2) is measured. It parallels cardiac output and is a significant prognostic indicator for chronic heart failure, but is not a direct assessment of ventricular performance and indeed peak cardiac output could be better in prognostication25.

Noninvasive measurement of cardiac output during exercise using the NICOM could be useful in this evaluation. The relationships between peak VO2 and peak cardiac index (CI) were similar for directly measured CI (r = 0.61) and noninvasive CI (r = 0.61)26. In a multicentre study, noninvasive measurements of cardiac output at rest and during exertion identified abnormalities of cardiovascular function consistent with those identified by pVO2 and in prior studies using invasive CO measurements27.

Cardiac Resynchronisation Therapy
In those with a cardiac resynchronisation device in situ, NICOM can determine the optimal AV and VV delay settings so that the device can be fine-tuned to optimise stroke volume without the need for echocardiography and other tests requiring special skills28, 29.

Haemodialysis
The NICOM system has been used in dialysis patients with a view towards early warning of haemodynamic decompensation and optimisation of fluid balance30.

Conclusion:
Minimally invasive and non-invasive cardiac output monitoring represents another numerical trend monitor which needs to be used alongside clinical assessment in delivery of goal directed management customised to individual patients.

Assessment and augmentation of global oxygen delivery can improve outcome in critically ill patients. These devices can be used to provide continous objective monitoring to guide management in a patient care pathway, especially one requiring careful optimisation of fluids.

Given that catheter related blood stream infections carry a significant mortality and morbidity with them, the adoption of a noninvasive monitoring method can contribute to improved patient safety and improved economic utilisation in critical care. While the NICOM system certainly seems to be the least invasive cardiac output monitoring method currently available, clinicians may well seek further evidence to support its use over minimally invasive cardiac output monitoring in the critical care setting.

Likewise, further evidence to support its use in critically ill patients pre-admission to the intensive therapy unit would be useful. Limitation in providing more discrete parameters like extravascular lung water may be relevant in specific patient groups.

It should be emphasised that clinical acumen including assessment and clinical examination are still of utmost importance and that accuracy of absolute values may be less important than trends when determining fluid status. It is important to appreciate that each device has its inherent limitations and no cardiac output device can change patient outcome unless it is coupled with an intervention that by itself has been associated with improved patient outcome.

References
  1. Connors AF Jr, Speroff T, Dawson NV, et al. The effectiveness of right heart catheterisation in the initial care of critically ill patients. SUPPORT investigators JAMA 1996, 276:889-897
  2. Harvey S, Harrison DA, Singer M, et al. Assessment of clinical effectiveness of Pulmonary artery catheter in management of patients in ICU (PAC-Man): Randomised control trial. Lancet 2005, 366: 472-477
  3. Harvey SE, Welch CA, Harrison DA, Rowan KM, Singer M. Post hoc insights from PAC-Man – the U.K. pulmonary artery catheter trial. Critical Care Medicine 2008 Jun; 36(6):1714-21
  4. Barin E, Haryadi D, Schookin S, Westenskow D, Zubenko V, Beliaev K, Morozov A Evaluation of a thoracic bioimpedance cardiac output monitor during cardiac catheterization. Crit Care Med 2000;28:698–702
  5. Bernstein DP, Continuous noninvasive real-time monitoring of stroke volume and cardiac outputby thoracic electrical bioimpedance. Crit Care Med 1986;14:898–901
  6. Spiess B, Patel M, Soltow L, Wright I, Comparison of bioimpedance versus thermodilution cardiac output during cardiac surgery: evaluation of a second generation bioimpedance device. J Cardiothorac Vasc Anesth 2001, 15:567–573
  7. Packer M, Abraham WT, Mehra MR, et al: Utility of Impedance Cardiography for the Identification of Short-Term Risk of Clinical Decompensation in Stable Patients With Chronic Heart Failure. J Am Coll Cardiol. 2006 ;47(11):2245-52
  8. Squara P, Denjean D, Estagnasie P, et al. Noninvasive Cardiac Output Monitoring (NICOM): a Clinical Validation. Intensive Care Med. 2007 Jul;33(7):1911-19145.
  9. Wakeling HG, McFall MR, Jenkins CS, Woods WG, Miles WF, Barclay GR, Fleming SC: Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaesth 2005, 95:634-642.
  10. Abbas SM, Hill AG: Systematic review of the literature for the use of Oesophageal Doppler monitor for fluid replacement in major abdominal surgery. Anaesthesia 2008, 63:44-51.
  11. Engoren M, Barbee D. Comparison of cardiac output determined by bioimpedance, thermodilution, and the Fick method. Am J Crit Care 2005, 14:40–45
  12. Raval NY, Squara P, Cleman M, et al. Multicenter evaluation of noninvasive cardiac output measurement by Bioreactance technique. Journal of Clinical Monitoring and Computing 2008; 22(2):113-9
  13. Lelyveld-Haas LE, van Zanten AR, Borm GF, Tjan DH: Clinical validation of the non-invasive cardiac output monitor USCOM-1A in critically ill patients. Eur J Anaesthesiol 2008, 25:917-924.
  14. Keren H, Burkhoff D, Squara P. Evaluation of a noninvasive continuous cardiac output monitoring system based on thoracic bioreactance. Am J Physiol Heart Circ Physiol 2007; 293:H583–H589.
  15. Marqué S, Cariou A, Chiche JD, Squara P: Comparison between Flotrac-Vigileo and Bioreactance, a totally noninvasive method for cardiac output monitoring. Crit Care 2009, May 19;13(3):R73
  16. Squara P, Rotcajg D, Denjean D, et al. Comparison of monitoring performance of Bioreactance vs. Pulse Contour during recruitment Maneuvers. Crit Care 2009;13(4):R125
  17. Rivers E, Nguyen B, Havstad S, et al.: Early goal directed therapy in the treatment of severe sepsis and septic shock. New England Journal of Medicine 2001, 345:1368-1377
  18. Grocott MPW, Hamilton MA, Bennett ED, Harrison D, Rowan K: Perioperative increase in global blood flow to explicit defined goals and outcomes following surgery (Cochrane Protocol). Cochrane Database Syst Rev 2006
  19. Lees N, Hamilton M, Rhodes A, Clinical review: Goal directed therapy in high risk surgical patients Critical Care 2009, 13:231
  20. Pearse R, Dawson D, Fawcett J, Rhodes A, Grounds RM, Bennett ED: Early goal directed therapy after major surgery reduces complications and duration of hospital stay. A randomised controlled trial. Crit Care 2005, 9; R687-R693
  21. Bishop M, Shoemaker WC, Appel PL, et al Prospective, Randomized trial of survivor values of cardiac Index, oxygen delivery, and oxygen consumption as resuscitation endpoints in severe trauma. J Trauma. 1995; 38(5):780-7.
  22. Benomar B, Ouattara A, Estagnasie P, et al. Fluid responsiveness predicted by noninvasive Bioreactance-based passive leg raise test Intensive Care Med. 2010;36(11):1875-81
  23. Benoit J, Hicks C, Kolattukudy S, et al. Hemodynamic changes as a diagnostic tool for acute heart failure. Academic Emergency Medicine 2009;16(s1):S11
  24. Hicks CW, Benoit J, Kolattukudy S, et al. Hemodynamic changes in patients with sepsis. Society of Academic Emergency Medicine, 2009
  25. Lang CC, Karlin P, Haythe J, et al: Peak cardiac power output, measured non-invasively, is a powerful predictor of outcome in chronic heart failure. Circulation. In press
  26. Myers J, Gujja P, Neelagaru S, et al. Cardiac output and cardiopulmonary responses to exercise in heart failure: application of a new Bio-reactance device. J Card Fail. 2007 Oct; 13(8):629-36
  27. Maurer MM, Burkhoff D, Maybaum S, et al. Exercise cardiac output provides important information in the evaluation of heart failure patients: A Multicenter Study of Noninvasive Cardiac Output by Bioreactance during Symptom-Limited Exercise. Journal of Cardiac Failure. 2009; 15(8):689-99.
  28. Khan FZ, Salahshouri P, Matsouva D, et al. Correlation of novel non-invasive Bioreactance based haemodynamic measurements with pulsed Doppler of the transmitral inflow for optimization of AV intervals in cardiac resynchronization therapy. Heart Rhythm 2009 Vol 6, Issue 5S PO 03-134
  29. Khan FZ, Read PA, Salahshouri P, et al. Comparison of Doppler Echocardiography with non invasive cardiac output monitoring based on Bioreactance for AV and VV delay optimization in patients undergoing cardiac resynchronization therapy. Europace Journal 2009, 11(Supplement 2), A1014.
  30. Kossari N, Hufnagel G, Squara P. BIOREACTANCE: A New tool for cardiac output and thoracic fluid content monitoring during hemodialysis. Hemodial Int. 2009 Sep 16

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Ankle block under ultrasound guidance
Authors: Dr Rajib Dutta,1 Dr S Qureshi,2 Dr N Patel,3

1Specialist Registrar in Anaesthesia and Chronic pain, King’s College Hospital NHS Foundation Trust, Denmark Hill, London
2ST4 in Anaesthesia, King’s College Hospital
3ST3 in Anaesthesia, Bristol Royal Infirmary

JAP 2011: 5: 170-173.


Abstract
The ankle block is a safe and effective method for obtaining anaesthesia and analgesia of the foot for surgical procedures on bones and soft tissues.

An ankle block is a block of four branches of the sciatic nerve (tibial, sural, deep and superficial peroneal nerves) and one cutaneous branch of the femoral nerve (saphenous nerve). The superficial peroneal, sural and saphenous nerves have cutaneous distributions and can be blocked by subcutaneous infiltration. The posterior tibial and deep peroneal nerves supply deeper structures including bones and muscles and require injection of local anaesthetic beneath the superficial fascia.

Ultrasound offers actual visualisation of the nerves and demonstrates real time needle placement and local anaesthetic spread. It is especially helpful in blocking the tibial1 and deep peroneal nerves, thus improving the quality of analgesia and anaesthesia obtained with this regional technique.
Anatomy
The five peripheral nerves that supply innervation to the foot are the terminal branches of the sciatic and femoral nerves. The sciatic nerve gives rise to the posterior tibial, deep peroneal, superficial peroneal and sural nerves. The femoral nerve terminates in the saphenous nerve.

Sciatic nerve
The sciatic nerve is the longest and largest nerve in the human body. It arises from the lumbrosacral plexus (L4, L5, S1, S2, S3) to provide motor and sensory innervation to the lower extremity. The sciatic nerve emerges from the pelvis via the greater sciatic foramen below the piriformis muscle & enters the thigh between the ischial tuberosity & greater trochanter. The sciatic nerve then enters the thigh deep to the lower border of gluteus maximus . It descends near the midline of the posterior aspect of the thigh and divides into the common peroneal and tibial branches, usually in the popliteal fossa.

The common peroneal nerve descends along the tendon of the biceps femoris muscle and loops around the neck of the fibula, below which it divides into its terminal branches: the deep peroneal and superficial peroneal nerves.

The superficial peroneal nerve emerges from the anterolateral compartment of the lower part of the leg and surfaces from beneath the fascia 5-10 cm above the lateral malleolus. It provides sensory innervations to the dorsum of the foot apart from the first web space, which is supplied by the deep peroneal nerve.

The deep peroneal nerve runs below the layers of peroneus longus, extensor digitorum longus, and extensor hallucis longus muscles. It continues between the anterior tibial artery and the extensor digitorum longus muscle where it divides into medial and lateral branches. The medial branch innervates the first web space between the big toe and the second toe whilst the lateral branch innervates the tarsometatarsal, metatarsophalangeal, and interphalageal joints of the lesser toes.

The tibial nerve divides into the posterior tibial and sural nerve. The posterior tibial nerve enters the foot behind the medial malleolus between the posterior tibial artery and Achilles tendon. Just beneath the medial malleolus the nerve further divides into the lateral and medial plantar nerves providing sensory supply to the sole of the foot.

The sural nerve arises from the tibial nerve and has a variable subcutaneous anatomical location posterior to the lateral malleolus and anterior to the Achilles tendon. It supplies sensation to the lateral aspect of the foot, including the fifth toe.

Femoral nerve
Of the five nerves blocked, only the saphenous nerve arises from the femoral nerve. It supplies sensory innervation to the anterior side of the lower leg + medial side of the foot/sole (back part) and the medial inner ankle.

Indications of Ankle block
  • Surgery on the foot and toes
  • Analgesia for procedures on the foot and ankle
Contraindications of Ankle block
Absolute contraindications
  • Patient refusal
  • Injection site infection Relative contraindications
  • Patient on systemic anticoagulation or bleeding disorders
  • Systemic infection
Complications of ankle block
  • Infection
  • Bleeding
  • Injury to blood vessels
  • Injury to adjacent structures
  • Temporary or permanent nerve damage
  • Local anaesthetic toxicity
Ultrasound vs. traditional approach
  • Ultrasound helps to see the anatomy and demonstrates both the real time needle advancement and spread of local anaesthetics2
  • Ultrasound combined with nerve stimulation has been shown to increase the success rate of block in comparison to the anatomical technique3
  • It also reduces patient discomfort and number of needle passes4
Ultrasound equipment
Ultrasound has many applications in clinical practice. Using the same unit but with different probes it is possible to visualise peripheral nerves, blood vessels, and heart, lungs and other abdominal viscera. There are few changeable variables such as gain, resolution and depth. These are changed to optimise picturequality. Colour could be applied to identify blood vessels which help to distinguish nerves from blood vessels and avoid serious complications.

Figure 1. Dermatomal distribution of nerves supplying the foot. Image modified from http://www.cambridgeorthopaedics.com. Figure 2. Sonosite NanoMaxx with 10-5MHz linear probe. Image courtesy of Sonosite UK.
Transducers (Ultrasound Probes)
The probes, which consists of piezoelectric crystals, transmits ultrasonic waves and receives reflected ultrasound beam which depend on the acoustic impedance. 2D images of structures are displayed on the screen. Visualising the nerves by sound waves requires the use of high frequencies (10 to 15 MHz) offering high resolution images. The advantage of broadband transducers (band width of 5-12 MHz) is that they provide excellent resolution of superficial structures in the upper frequencies and good penetration of depth in the lower frequency range.

Figure 3. In plane approach for blocking tibial nerve at the ankle. Figure 4. Ultrasound appearance of the tibial nerve lying posterior to the posterior tibial artery.
Sonographic appearance of peripheral nerves
The US appearance of a nerve primarily depends on its size, and the amount and make-up of the support tissue (epineurium and perineurium). Fascicles (collection of axons) appear black (hypoechoic) and the supporting tissue appear as bright (hyperechoic). At different levels (roots, trunks and peripherally) the same nerve may vary in appearance from being hypoechoic (bubbles/holes at the roots) to hyperechoic ovoid, triangular or flattened structures in the periphery. This possibly because, of the changing nature of the fascicle covering of the nerves as they divide and pass through different tissue.

Appearance of the nerves may be dark (hypoechoic) or bright (hyperechoic) depending on the size of the nerve, sonographic frequency and the angle of the beam. In a transverse section nerves will appear as hypoechoeic structure surrounded by hyperechoeic structure. In a longitudinal view, each nerve may appear as hypoechoeic stripes separated by hyperechoeic lines. The appearance also depends on the location of the nerve (e.g. interscalene nerves: dark whereas the median nerve appears bright)

Figure 5. Out of plane approach for blocking the deep peroneal nerve in the ankle. Figure 6. ultrasound appearance of the deep peroneal nerve lying immediately lateral to the dorsalis pedis artery.
Problems in practice
The ultrasound beams cannot pass through air-filled pockets. It is important to ensure adequate jell is applied to the probe to minimise the artifacts.

Visibility of structures could change with angle of the probe. Adjusting the angle of the probe is an important part of scanning technique.

Positioning
The patient lies in the supine position with the ankle elevated with a bolster to access all the nerves.

Equipment
  • A high frequency linear probe (10-5Mhz)
  • 22g 50mm stimulating needle with catheter
  • 4, 10 mls syringes filled with local anaesthetic
  • 1, long 25g hypodermic needle
  • 1, short 25g hypodermic needle
  • Local anaesthetic choice: 50:50 0.5% L Bupivacaine and 2% Lignocaine
  • IV access
  • Standard monitoring
  • Drugs for sedation
  • Skin preparation with 0.5% to 2% chlorhexidine with 70% isopropyl alcohol
Scanning technique, anatomical correlation, nerve localisation and needle insertion approaches

Tibial nerve:
  • Transducer preparation
  • External rotation of ankle and probe is placed posterior to and below the medial malleolus transversely
  • Image is optimised by adjusting the depth (1-2 cm), focus (1-2 cm) and gain
  • The posterior tibial artery is round and hypoechoic
  • The posterior tibial nerve usually lies posterior to the artery and is hyper echoic, round with a honeycomb appearance. It lies deep to the fascial planes. The nerve should be traced proximally to the leg in order to differentiate from the tibialis posterior and flexor digitorum longus tendons
  • Both in plane and out of plane needle insertion approaches are used. Most of those who start with RA and US is that out of plane is used till they become familiarised and then the “in-line” approach is applied.
Deep Peroneal nerve:
  • Dorsalis paedis artery identified between the two malleoli.
  • The deep peroneal nerve usually lies lateral to the extensor hallucis longus tendon, but is often difficult to see.
  • Out of plane needle insertion approach on both sides of dorsalis paedis artery is done for the block.
Saphenous nerve:
  • It is difficult to visualise the saphenous nerve below the knee. Placing a tourniquet around the leg distends the subcutaneous saphenous vein and makes the nerve easily visible, since it lies next to the vein
  • External rotation of ankle and probe is placed posterior to and above the medial malleolus transversely
  • Out of plane needle insertion approach
  • A peri-venous injection around the great saphenous vein proximal to the ankle will suffice
Superficial peroneal and Sural nerves:
  • These are blocked by subcutaneous infiltration without the use of ultrasound.
  • The superficial peroneal and sural nerves are found in the subcutaneous tissue along a circular line that starts from the lateral side of the Achilles tendon across the lateral malleolus, anterior aspect of the foot, and medial malleolus to the medial side of the Achilles tendon.
  • These nerves are blocked by a circumferential injection of local anaesthetic subcutaneously along this circular line.
Local anaesthetic injection
  • 3-5 mls of 50:50 0.5% L Bupivacaine and 2% Lignocaine is injected at each site after being satisfied with needle position and negative aspiration (total 20 -25 ml)
  • The local anaesthetic spread is seen in real time and a hypoechoic circumferential spread gives best result
  • If circumferential spread is not obtained, it is important to inject on both sides of the nerve
  • The nerves need to be scanned in transverse and longitudinal planes proximally and distally to check the extent of local anaesthetic spread.
Ultrasound-Guided vs Anatomic Landmark-Guided Ankle Blocks
  • In the hands of less experienced practitioners, US guided technique improves clinical efficacy in comparison to the anatomical landmark technique5
  • US guidance resulted in more successful tibial nerve block at the ankle than a traditional approach using surface landmarks6
Other US guided approaches for foot surgery
Other approaches described are US guided popliteal block proximal and distal to sciatic nerve bifurcation7 combined with various approaches to block the saphenous nerve8 by US techniques. One of the advantages of the sciatic –saphenous block is less injections compared to the five injections with the ankle block technique.

Summary
Ultrasound guidance is helpful in blocking the tibial, deep peroneal and saphenous nerves in the ankle. Although we do not use ultrasound to block the superficial nerves at the ankle, with the advancement of ultrasound technology and increasing resolution, the superficial nerves will be better visualised and will be successfully blocked in the near future as well.

The actual visualisation combined with real time injection provides successful block and decreases the need for sedation or general anaesthetics.

Due to the use of the 50:50 combination of 2% lignocaine and 0.5% bupivacaine, duration of block is decreased. The lower volume used also facilitates ambulation. The selective block preserves motor function of legs, thus helping in early discharge of patients. This helps to decrease costs in the day surgery units.

References
  1. Wassef MR. Posterior tibial nerve block. A new approach using the bony landmark of the sustentaculum tali. Anaesthesia 1991; 46: 841-4
  2. Chan VW. Nerve localization--seek but not so easy to find? Reg Anesth Pain Med 2002; 27:245-8
  3. Macfarlane AJR, Chin KJ, Brull R. Ultrasound guided ankle blocks - a retrospective review of 501 cases. Abstract accepted for ASA annual meeting, 2008
  4. Casati A, Danelli G, Baciarello M, Corradi M, Leone S, Di Cianni S, Fanelli G. A prospective, randomized comparison between ultrasound and nerve stimulation guidance for multiple injection axillary brachial plexus block. Anesthesiology 2007;106: 992-6
  5. Chin KJ, Wong NW, Macfarlane AJ, Chan VW. Ultrasound-Guided Versus Anatomic Landmark-Guided AnkleBlocks: A 6-Year Retrospective Review. Reg Anesth Pain Med.2011 Sep 20. [Epub ahead of print]
  6. Redborg KE, Antonakakis JG, Beach ML, Chinn CD, Sites BD. Ultrasound improves the success rate of a tibial nerve block at the ankle. Reg Anesth Pain Med 2009;34(3):256-60
  7. Prasad A, Perlas A, Ramlogan R, Brull R, Chan V.Ultrasound-guided popliteal block distal to sciatic nerve bifurcation shortens onset time: a prospective randomized double-blind study. Reg Anesth Pain Med 2010;35(3):267-71.
  8. Saranteas T, Anagnostis G, Paraskeuopoulos T, Koulalis D, Kokkalis Z, Nakou M et al.Anatomy and clinical implications of the ultrasound-guided subsartorial saphenous nerve block. Reg Anesth Pain Med 2011;36(4):399-402.

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CRITICAL CARE CHALLENGES: Management of unsurvivable diffuse axonal injury; identifying the potential heart beating organ donor
Author: Mark Snazelle11ST7 in Anaesthetics at Guy’s and St Thomas’ NHS Trust
JAP 2011: 5; 174-186.

This case represents an extremely difficult scenario for the critical care practitioner. It raises many of the complex and emotive issues surrounding unsurvivable

brain injury for all involved, and the difficulties encountered when attempting to enable organ donation.

A 23 year old man was admitted after a high speed road traffic accident. He required extrication from his vehicle at the scene, during which time his

Glasgow Coma Score (GCS) was noted to be 3, and his pupils were fixed and dilated. He was intubated and ventilated at the scene and administered 5% hypertonic saline.

On arrival to the Accident and Emergency department, the patient was haemodynamically stable. The major findings of the primary survey were fixed dilated pupils and signs of facial trauma. FAST scanning was negative and after blood sampling and trauma X-rays were performed, the patient was transferred immediately for CT scanning.

CT of his brain showed swelling and loss of grey/white differentiation thought to be consistent with a severe diffuse axonal injury. The neurosurgeons were consulted but their opinion was that the injury was unsurvivable and that there were no active treatment options. Subsequent arrangements were made to transfer the patient to the intensive care unit for stabilisation followed by weaning of sedation and clinical assessment of neurological status. Before transferring to ITU the family were informed of his injuries and poor prognosis.

The patient was transferred to ITU where a neuroprotection care bundle was adhered to (head up tilt to 30o, PaCO2 4.5 – 5kPa, MAP >80mmHg, normothermia). No ICP bolt was placed in view of the neurosurgical assessment. The pupils remained fixed and dilated.

After the neuromuscular blockade had worn off, the patient appeared to make some respiratory effort. This was confirmed by placing the patient briefly on pressure support where spontaneous tidal volumes were maintained. The patient was returned to a mandatory mode for PaCO2 control.

Over the course of the subsequent day, the patient became polyuric, with urine and plasma osmolalities consistent diabetes insipidus. Half the hourly urine output was replaced with 0.45% saline solution. Early contact was made with the transplant coordinator despite the clinical picture not yet being consistent with brainstem death at it was felt that this would indeed be the likely outcome.

Twenty four hours after admission there was no further evidence of respiratory effort and his pupils remained fixed and dilated. A provisional diagnosis of brainstem death was discussed with the family and the need for brainstem testing (BST) explained. The BST was delayed for a time as some members of the family became threatening and abusive towards staff, but when finally conducted confirmed the diagnosis.

The results of the BST were explained to the family and then potential organ donation was discussed with them by the transplant coordinator. After long, difficult discussions with the family, involving further emotional and aggressive outbursts aimed primarily towards staff members, the family decided that they did not want him to be considered for organ donation.

Discussion
The notion of “brain death” was first described in the late 1950s, and was formally defined by the Harvard committee in 19681. Brain stem death is now recognised as a legal definition of death in most western countries. Whilst the causes of brain stem death vary considerably, approximately 80-90% of patients who develop brainstem death are admitted to intensive care with traumatic brain injury, subarachnoid haemorrhage or intracranial haemorrhage2.

A chronic shortage of donor organs remains a problem in this country and others and many patients with hopeless neurological prognosis are not always identified as possible donors3. Early identification of potential donors and optimum management until point of organ harvest is therefore essential. In addition, medical staff must remain acutely aware of the emotive nature of this issue and emotional support of the family must be provided throughout.

Continuing life sustaining treatment in the face of hopeless neurological prognosis is often problematic, and early recognition of such patients would allow more time to optimise organ donation itself4, and provide more opportunity for liaison with the family (potentially giving them at least some more time to absorb the information given to them). A recent Dutch paper suggests formal criteria for determination of “imminent brain death” which could be used as a point of departure for potential heart-beating organ donor recognition3, potentially formalising the whole recognition to donation process.

How best to communicate with families of potential donors, to maximise consent is a difficult issue. Families are more willing to give consent for donation when they have been given sufficient information about brain death and organ donation such that they can make an informed decision (and enough time in which to make that decision)5, 6.

The issue of whether consent is presumed or not has been discussed at length in recent years. In presumed consent (also known as dual advocacy) families are given the opportunity to donate rather than the option, and the requester is there more to help with the process of donation rather than the decision of whether to donate or not7. Legally it is presumed that the patient would give consent unless specifically stated otherwise. This has been argued by many to be a way of potentially increasing yield, as has the more formal opt-out versus opt-in system, although the ethical debate surrounding such changes in law continues. The UK nonetheless, continues to have a severe organ donor shortfall which currently shows little sign of improvement.

Conclusions
Organ donation is an extremely emotive subject and balancing the needs of those on the transplant lists, with those of the families of potential organ donors should not be underestimated. Whilst dedicated local transplant coordinators have undoubtedly improved the service provided both to families and potential recipients alike, the issue of discussing organ donation with families acutely at the time of death of a loved one remains extremely difficult.

The difficulty of the position that critical care practitioners find themselves in should also not be underestimated. Having to manage the medical requirements of the potential donor, as well as imparting information to relatives, can be extremely challenging, from both clinical and emotional perspectives. Prompt, early referral to a transplant coordination team is essential in all such situations.

References
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