Minutes from the Joint Meeting between the Section of Anaesthesia of the Manchester Medical Society and the Liverpool Society of Anaesthetists
Thursday 21st March 2013, Park Royal Hotel, Warrington
'Fringe Benefits – Anaesthesia beyond the Operating Theatre'
The meeting was opened by the President of the Section of Anaesthesia of the Manchester Medical Society, Dr Johanna Ryan, who introduced the first speaker.
Dr Mo Gnanalingham, Consultant Paediatrician, Central Manchester University Hospitals
Dr Gnanalingham started his talk with a simple scenario. He presented a 2 day old neonate presenting with a 24 hour history of poor feeding and lethargy. The child was tachycardic, tachypnoeic, hypotensive, cold and had already had 2 asystolic cardiac arrests. After asking the audience what else they would like to know, he gave some further information, demonstrating that the baby was profoundly acidotic with other deranged physiology. He presented a differential diagnosis of sepsis, congenital heart disease or a congenital metabolic disorder. He highlighted the main issues which were persistent acidosis, resistant hypotension, multi-organ failure and disseminated intravascular coagulation as well as limited venous access. The principal treatment, was first to gain better access to the circulation, with the intra-osseous route being the most straightforward. Intubation and ventilation should be established followed by generous volume resuscitation and appropriate inotropes. The most likely diagnosis was sepsis in this case.
Dr Gnanalingham suggested that in the UK, the emergency management of children with severe sepsis, should be good. However, he cited a paper: Arch Dis Child 2009;94:5 348-353, which demonstrated that most children presenting with this condition received inadequate fluid resuscitation and inotropic support This is absolutely crucial in the first few hours of presentation because it influences outcomes. He stated that it was well established that children required up to 60mls/kg of fluid in the first hours of fluid resuscitation and failure to reverse septic shock doubles the risk of death with each hour that it persists.
Dr Gnanalingham said it was important to do the basics well, which included better oxygen delivery through intubation and ventilation as well as good quality circulatory access as soon as possible. He went through the common manifestations of septic shock, in particular the red flags indicating severe sepsis. These included rapid deterioration in the preceding 6 hours, a white count of less than 2 or more than 30x109/l, a platelet count <50, hypoglycaemia, hypothermia, altered level of consciousness, oliguria, and deranged liver function tests. If bacteria were actually seen on a blood film, he commented that this was invariably a very poor prognostic sign. Children with severe sepsis needed a combined team approach with both anaesthetists and paediatricians being involved.
Dr Gnanalingham turned his attention to ventilation. He said the triggers for intubation were either a decreasing or fluctuating level of consciousness, signs of respiratory failure, exhaustion or shock, apparently refractory to fluid resuscitation. He commented that peak airway pressures should always remain less than 30 cmsH2O even if pulmonary oedema was present and increasing PEEP was more useful than Frusemide.
Dr Gnanalingham then looked at fluid and inotropic therapy. He again stressed the large volumes of fluid that can be required in the first 24 hours which may be up to 360 mls/kg, and the importance of getting an adequate amount into a sick child in the first couple of hours. He highlighted the importance of blood transfusion, improving oxygen delivery as well as blood volume as well as giving platelets, particularly if there was profound thrombocytopenia (<10 x 109/l). A platelet count of more than 50 was important when surgery or invasive procedures were about to be undertaken. He said the end point for fluid resuscitation was a return of urine output, an improvement in the level of consciousness, normal pulses throughout and warm peripheries. A mixed venous SpO2 should return to >70% with a fall in lactate levels. He briefly spoke about inotropes and their transient use to maintain perfusion whilst correcting hypovolaemia. The important thing was to continue giving fluids which was often forgotten.
Dr Gnanalingham discussed some recent guidelines (Crit Care Med. 2009 Feb;37(2):666-88). He commented on their rather didactic nature but stated that outcomes were improved when best practice guidelines were followed. Factors associated with poor outcomes included failure to have the involvement of paediatricians, inadequate supervision of junior and inexperienced staff and failure to reverse shock, particularly in the early stages.
In summary, Dr Gnanalingham thought that the important points were having an appropriate team involvement, an appropriate differential diagnosis, aggressive fluid resuscitation when warranted with targeted end points, and the early use of inotropes if needed.
Dr Tom Hurst, King’s College Hospital, London
Dr Hurst began his talk by looking at the training required for pre-hospital emergency medicine (PHEM) which had been agreed in principle by the Royal College of Anaesthetists, the Faculty of Emergency Medicine, the Royal College of General Practitioners, and the Royal College of Surgeons of Edinburgh. This would require an additional 12 months of speciality training which could be done at various points during training or all at once as part of a CCT in the parent specialty. The definition of pre-hospital emergency medicine was the speciality provision on scene and in transit of critical care. He looked at the 2011 curriculum with the GMC’s Good Medical Practice as the over-arching theme. He began by speaking about each of the sub-specialty specific themes. The first was working in emergency medical systems which described how emergency medical services worked in the pre-hospital operational environment. He stressed the importance of having an understanding of what the roles of the paramedical services were and how these integrated with pre-hospital emergency provision. This led into the second theme of providing pre-hospital emergency medical care in a relatively unsupported environment. This required a greater depth of knowledge of resuscitation in all age groups and in different circumstances. Dr Hurst gave an example of a motor cyclist injured in a road traffic accident who had a traumatic brain injury, a chest injury as well as a spinal fracture and splenic lacerations. This highlighted the decision making required to either transfer the injured patient with no on-site treatment to the nearest A&E Department, which may only be 10 minutes away, or stay on-site for stabilisation and subsequent transfer in a more controlled way to the regional trauma unit.
Dr Hurst then looked at the next topic of supporting rescue and extrication which required an understanding of the roles of the other services and the clinical requirement to safely extricate a trapped patient. The followingt theme was the safe use of equipment. Dr Hurst said how important it was to ensure that all necessary equipment was taken to the scene, requiring proper preparation prior to any call out. Once the patient had been extricated, the support of transfer was discussed and Dr Hurst presented an example of what was required of the team.
The final theme was supporting emergency preparedness and response which ensured that practitioners were appropriately prepared and equipped for large scale emergency incidents so that they understand the concepts of emergency planning and the principles of major incident management.
Dr Hurst finally spoke about the three cross cutting themes of operational practice, team resource management and clinical governance, which concluded his talk.
'Exra Corporeal Membrane Oxygenation (ECMO)'
Dr Julian Barker, University Hospital of South Manchester
Dr Barker started his talk by looking at the history of ECMO which had been initially used for the supportive treatment of patients having recently received an organ transplant. Typically ECMO was required for 2 to 3 days before the transplanted organ started working adequately and the transplant unit had had a number of years’ experience with this method. In 2009/10, the winter swine flu epidemic had swamped all the usual ECMO centres and consequently transplant centres were asked to provide these facilities for these previously healthy, fit and young, patients. This was agreed but most ECMO beds at the transplant centres were not actually required. However, the following year, far more patients presented and therefore the capacity of transplant units was used. The main difference between these 2 groups of patients was that ECMO in non-transplant patients lasted not days but typically 2-3 weeks. This required considerable team effort and use of resources.
Dr Barker then considered patient selection for ECMO. He stated that the most important condition was one that was reversible. It was therefore an entirely appropriate treatment for the patient with single organ failure, for example, streptococcal pneumonia, trauma or younger patients with pancreatitis.
Dr Barker demonstrated how ECMO worked. He showed the large double lumen cannula normally inserted through the right internal jugular vein taking blood from the inferior and superior vena cavae and then delivering it oxygenated to the output lumen within the right atrium. He emphasised the large size of the catheter. Following referral of patients for ECMO, it was often easier to go to the referring hospital, place the patient on ECMO and transfer them in a more stable condition back to the unit. This was because once on ECMO, arterial oxygen content and pH improved and inotrope requirements reduced.
Dr Barker then looked at the question of whether ECMO actually works. He conceded that trials such as the CESAR trial (Lancet. 2009 Oct 17;374(9698):1351-63) had had equivocal results. However, in his opinion, there was no doubt that ECMO was a very effective treatment. He justified this by looking at other evidence based medical treatment which had had far stronger evidence to back up their uses but ultimately had failed to alter outcomes. He commented that since the original CESAR trial, much has changed. There was now better technology which was simpler, more reliable and with fewer complications. The results at UHSM showed upto 80% overall survival which was as high as 91% in those with swine flu.
Dr Barker then looked at the treatment of patients whilst on ECMO. This allowed the lungs to be rested although they were still gently ventilated with 30% oxygen with pressures of 20/10cmsH2O and this could last for upto 2-3 weeks. The major complication seemed to be bleeding, despite the fact that relatively little heparin was required to keep the ECMO circuit clot free. The exact mechanism for this bleeding was not known however, some patients had required thoracotomies, laparotomies and angiograms to find the source of bleeding.
Finally, Dr Barker paid tribute to all his team members and conceded that because of their high skill mix, this was a very expensive undertaking.
Dr Bernard Foëx, Central Manchester University Hospitals
Dr Foëx started by asking a question about how we decide which patients to treat when resources are limited. Was there a fair and just way of allocating this resource, or did it go to those who shouted loudest? He then gave some quotes about the rationing of medical care, which stated that it should be avoided because it might be inconsistent, discriminatory or ineffective and was not appropriate or ethical. He then came up with a common scenario in most hospitals where 4 patients needed the one available HDU bed and asked the audience which one should have it, and how would they choose?
Dr Foëx then discussed the basic principles of medical ethics as described by Beauchamp and Childress of beneficence, non-maleficence, autonomy and distributive justice. Although these principles may be important, they are not always helpful in deciding how to distribute scarce resources. Persad et al (Lancet 2009; 373: 423–31) described 4 principles for their allocation. These could be treating all people equally, favouring the worst off, maximising total benefits or promoting and rewarding social usefulness. However, each has a problem. By treating people equally, there may be a lottery or “first come, first served”, both of which will not allocate resources sensibly. Favouring the worst off first, can also have its problems although this is often how patients are triaged in the A&E Department. Nevertheless there can be anomalies such as favouring the young over the old. Dr Foëx then looked at other allocation systems, such as the united network for organ sharing which prioritised people on the severity of the current medical condition, their waiting time and prognosis. The use of QUALYS was a way of allocating resources in health policy rather than case by case. The complete life system prioritises those who have not lived a complete life and will not do so without a particular intervention.However, it does incorporate prognosis to overcome the problems of the resources being unfairly allocated to very young with a very poor prognosis.
Dr Foëx then looked at the words of Aristotle who said “justice is equality, but only for the equal, and justice is inequality, but only for those who are unequal”. Using this principle, the inequalities maybe the need for organ support and the ability to benefit, however the irrelevant inequalities may be gender and life choices. Dr Foëx felt our allocation system should recognise morally relevant values. It should also have legitimacy by being seen to be just and this justification should be publically debated, understood, accepted and open to revision. He then looked at Jonsen’s four box approach to the ethics of patient treatment. The first was the medical indication, which included the goals of treatment and the probability of success. The second was patient preference or autonomy which included informed consent and capacity to understand. The third was quality of life, including premorbid condition and prospects of returning to that condition following treatment. Finally, there were contextual factors such as religious or family views.
Finally, Dr Foëx looked to the future and showed the projected needs for critical care which were predicted to treble over the next 20 years. Inevitably there will be very difficult choices to make.
Dr Joseph Sebastian, Salford Royal Hospital.
Dr Sebastian started his talk by looking at the history of awake craniotomy which had apparently been practiced up to 7000 years ago, a long time before the advent of anaesthesia. Indeed he demonstrated a 4000 year old skull which had had a cranioplasty with a gold material. The indication for awake craniotomy today is to identify and preserve what are called the eloquent brain areas which are the functional area of the brain which regulate speech, movement and senses. He looked at how these areas had originally been identified in the 19th century.
Dr Sebastian spoke about his involvement in looking after patients undergoing awake craniotomy for the excision of low grade gliomas. These represented 15% of all adult brain tumours and were found in relatively young patients, most of whom present with fitting. These tumours often originate in the eloquent areas of the brain. Surgery to remove them has 3 stages; the first is gaining access by the removal of a bone flap; the second stage is intra-operative functional mapping and tumour resection where patients must be fully awake to ensure the best preservation of the eloquent areas of the brain, followed by closure. Often for stages 1 and 3, the patient can be anaesthetised or sedated.
Dr Sebastian went through the practical aspects for preparing a patient for this type of surgery and the many difficulties encountered. He then spoke about the recent introduction of Dexmedetomidine which had changed his practice. The drug produced a dose dependent sedation, from which it was easy to rouse patients. It also produced minimal respiratory depression as well as analgesia and anxiolysis. It had other positive effects such as decreasing anaesthetic requirements and sympatholysis It had no effect on intracranial pressure. He commented that alpha 2 adreno-receptor agonists had been around since the 1960’s with the introduction of Clonidine in human practice and Xylazine and Detomidine in veterinary practice. Dexmedetomidine had been available in the US since 1999 but had only been introduced into the UK in 2011 and is currently only licenced for ITU sedation for up to 14 days.
Dr Sebastian then turned to the pharmacology of Dexmedetomidine. He spoke about its actions on alpha 2 presynaptic receptors, modulating sympathetic responses by negative feedback. Its sites of action included the locus cereleus in the CNS which was responsible for sedation, anxiolysis and analgesia and locally in the spinal cord where its action in the substantia gelatinosa of the dorsal horn inhibits the firing of noceoceptive neurones and the release of Substance P. He reviewed the pharmacokinetics and demonstrated their favourable characteristics with an alpha half-life of 6 minutes and a beta half-life of 2 hours. The drug was metabolised in the liver and excreted in the kidneys with no accumulation over a 14 day treatment period. He then compared it with Clonidine and showed the much greater alpha 2 affinity of Dexmedetomidine at 1,620 to 1, compared to Clonidine’s 200 to 1. This perhaps explained why Dexmedetomidine was a better sedative compared with Clonidine.
Finallly, Dr Sebastian looked at other uses for Dexmedetomidine anaesthesia, including its use as an adjunct to general anaesthesia, as a sedative, both in an outside theatre and for sedation in other areas such as paediatric intensive care and the MRI unit.
The meeting concluded with the Liverpool President, Dr Janice Fazackerley, giving the vote of thanks.
24th March 2013