‘NAP4; Major Complications of Airway Management’
Dr Nick Woodall,
Norfolk and Norwich University Hospital
Dr Jane Harper,
Royal Liverpool University Hospital
The meeting was opened by the President, Dr Christine Bell, who welcomed the first speaker Dr Nick Woodall, Consultant Anaesthetist from Norfolk and Norwich Hospital who had been one of the principle investigators of the NAP 4 Project of the Royal College of Anaesthetists.
Dr Woodall began by looking at the headline figures. The report produced 184 major airway complications of which 133 had occurred in the operating theatre, 36 in the Intensive Care Unit and 15 in the Emergency Department. There had been 35 incidents of death or brain damage as a result of these major complications which put the incidence in this audit at 1:150,000. 58 incidents had required an emergency surgical airway putting that incidence at about 1:50,000. However, Dr Woodall emphasized that he felt there had been very significant under reporting and he thought the real frequency of death or brain damage as a result of major airway complications during anaesthesia was nearer 1:40,000 and that of any major complication of airway management during anaesthesia at about 1:5500. When major complications occur, more anaesthetists tend to be involved, in which case, the average anaesthetist would expect to be involved in a major complication of airway management in some way, approximately once every 6 years and in a case resulting in actual death or brain damage once in a career.
Dr Woodall then looked at the denominator in all these figures. In the 12 month period of the census there had been approximately 2.9 million anaesthetics given in operating theatres around the country. Approximately 58,000 patients had been intubated in the Intensive Care Unit of which 18 had had major complications producing an incidence of 1:3200. 20,000 anaesthetics had been given in the emergency department with 4 complications producing an incidence of 1:5000. He pointed out the far greater frequency of problems in Intensive Care and Emergency Departments compared to Operating Theatres. Dr Woodall commented that failure to use capnography in ventilated patients was a likely contributor to more than 70% of the ICU related deaths and the increasing use of continuous capnography on intubated and ventilated patients would be the single most important change to have the greatest potential to prevent deaths such as those reported to NAP 4.
Dr Woodall then looked at the anaesthesia review findings which demonstrated elements of poor management in 75% of cases with errors of judgement and deficiencies of training and education. There were failures of assessment, failures in planning and failures in planning for failure. Dr Woodall defined a major complication as one that led to firstly, permanent harm such as death or brain damage, secondly, patients undergoing emergency surgical airway and finally, patients requiring admission to Critical Care as a result of the airway complication.
Dr Woodall commented about the reporting pattern of incidents and there was often clustering in both time (when local reporters were reminded) and in location. Local reporters conveyed more complications of their own practice than of their colleagues. It was therefore felt by the investigating team that a substantial number of cases had been missed which may be up to 75%.
Dr Woodall looked at the demographic data for anaesthesia related cases. Contrary to expected findings, 50% of cases were either under 60 years of age, ASA I or II or elective/scheduled cases. Consultants were involved in nearly two thirds of cases and 69% occurred during daylight hours. BMI was an important factor with 40% of cases having a BMI greater than 30.
Dr Woodall then looked at the learning points from recommendations. Failure to correctly interpret a capnograph trace led to several oesophageal intubations going unrecognised. He emphasized that a flat capnography trace always indicated a misplaced tracheal tube or complete obstruction of the airway and this still applies during cardiac arrest as CPR maintains an attenuated but visible expired carbon dioxide trace. Another learning point was the poor success rate of crico-thyroidotomy. Various techniques were attempted but none seemed to be any more successful than the others. The single commonest cause of death due to anaesthesia related events involved aspiration of gastric contents. This occurred when anaesthetists failed to recognise the risk of aspiration or failed to use airway devices or techniques that offered increased protection against aspiration. The report also demonstrated that complications in obese patients were double those of the general population due to difficulty at tracheal intubation, airway obstruction during emergence or recovery and complications in the use of supraglottic airway devices.
72 of the 184 cases involved surgery of the head and neck. This group of patients require careful assessment co-ordinated planning and good team work between anaesthetist and surgeon. Bleeding into the airway or the neck was highlighted as a particular post-operative challenge. The obstructed airway always requires particular skill and co-operation between anaesthetist, surgeons and the theatre team. Tracheostomy under local anaesthesia should always be actively considered. When a surgical airway performed by a surgeon is the back-up plan, preparation should be made so that this can be instantly available in a fully equipped operating theatre with appropriate support. Awake fibre optic intubation is not without its difficulties due to failures with sedation and loss of the airway. However, it was not considered frequently enough due to poor judgement, lack of skills or a lack of suitable equipment being available.
38 of 133 anaesthesia events occurred during emergencies or recovery and airway obstruction was the cause in all cases. Half of these were associated with surgery in the airway. Overall in a third of events, airway management was judged to be poor. However, in approximately one fifth of cases airway management was judged to be exclusively good so major complications can still occur in the best hands.
Dr Woodall then looked at the response of the report. He thought that individuals should ensure that they have sufficient training in airway management and if individuals identify local deficiencies they should raise awareness at departmental level. Departments of Anaesthesia should identify lead anaesthetists for airway management so that they can organise a co-ordinated selection of equipment, produce or clarify departmental guidelines and ensure training is available to all members of the department. They should be responsible for raising awareness of any major deficiencies within the Trust to hospital management. Hospitals should ensure that all airway equipment is standardised throughout the organization and indeed at national level, guidelines for the standardisation of equipment and training will ensure that anaesthetists moving hospitals, particularly trainees, are not faced with new and different equipment every time they rotate. Dr Woodall concluded that NAP 4 may improve patient care but the onus is on anaesthetists to make it happen.
Dr Jane Harper from the Royal Liverpool Hospital took over the presentation and looked at complications in the Intensive Care and Emergency Departments. She looked at the state of play prior to NAP 4. It was already known that straight forward airway management becomes more difficult in Intensive Care and there was a significant frequency of accidental extubation and tracheostomy displacement. There were also staffing issues and less than a third of UK Units used capnography routinely. Only 50% of Intensive Care Units had difficult airway trolleys within them.
Dr Harper looked at NAP 4 results. Firstly, were 5 accidental extubations in ICUs leading to major airway complications of which there was one death. Three of these were in patients with a BMI greater than 30 and the remaining 2 were in patients with known difficult airways. In addition, there were 14 major airway complications from tracheostomy displacement of which 7 resulted in death. More than half were in patients with BMIs greater than 30, 3 with known difficult airways and 3 with previous difficulties with tracheostomies. Dr Harper commented that not all tubes were both taped and sutured to prevent misplacement. Tracheostomy design had also not appeared to have kept pace with the larger size of patient consequently leading to a greater incidence of complications in patients with higher BMIs. There were also 4 unrecognised oesophageal intubations, of which none had had capnography available.
Dr Harper then spoke about contributory factors. These included patient factors such as the reduced reserve of the critically ill and BMI greater than 30. Equipment was also important with lack of capnography being one of the most important contributing factors. When difficulties do arise in Critical Care, the lack of special equipment on a difficult airway trolley was also a major contributory factor. Poor planning or clinical judgement as well as inadequate training were also significant contributing factors. This was particularly the case with junior trainees or non-anaesthetic trainees. This is often compounded by a lack of experienced assistance in the non-theatre environment.
Many of the recommendations of the report were simple. Firstly, ensuring that the right practitioner with the right training, equipment, assistance in the right location were vital to ensure success. In addition capnography should be used for intubations in all circumstances and continuous capnography should be used in all ICU patients with tracheal tubes or tracheostomies and who are ventilator dependent. Having staff able to interpret capnography traces is also important. In the non-theatre environment, a check list should be developed and used for all intubations so that staff who are less familiar with this routine, have all the necessary equipment to hand. As well as every ICU having algorithms for the management of intubation, extubation and re-intubation there should also be plans for the management of inadvertent tracheal tube or tracheostomy displacement or obstruction.
Dr Harper went through some of the other recommendations. These included the presence of a difficult airway trolley in critical care with the same content and layout as in the theatre. There should also be a fibre optic bronchoscope immediately available for use on the ICU. Medical staff should also have regular mannequin based practice in the performance of cricothyroidotomy.
Dr Harper then looked at airway complications in the Emergency department where 15 cases had been reported of which 14 were the result of failed intubation. One in every 800 patients arriving in the Emergency department are intubated inferring a total of 20,000 patients per year. The frequency of major airway complications is 10 times higher than in theatre. 20% of intubations are carried out by emergency doctors rather than anaesthetists. Again the problems of high BMIs were highlighted with 7 cases out of 15 having a BMI greater than 30. Ten cases required an emergency surgical airway and 5 died or had brain damage. One of the main issues in the Emergency department were patients with facial trauma. The messages for the Emergency department were that only doctors with appropriate seniority and competency should be managing airways and when they do so they should have the appropriate equipment in the appropriate place. Dr Harper concluded by stating her view that, particularly in outside areas, for things to change, anaesthetists must own the problem.
After some questions taken from the floor Dr Pete Charters from Aintree Hospital gave a vote of thanks and the meeting closed at 20:30.
11th November 2011