So, for those who haven’t read NAP4 or aren’t aware of it, could you just explain more about the actual structure, and what answers you were seeking for the project? Sure. So the aim was to identify all cases for a period of a year in England, Northern Ireland, Scotland, and Wales of airway management complications that led to any of death, brain damage, front of neck airway as an emergency, or admission to ITU and, for those patients on ITU, prolongation of ITU stay. Over a period of a year we collected 184 of those cases. They were reported anonymously, and reviewed by a multidisciplinary committee to identify themes. So there’s a huge amount of qualitative learning.
Learning about themes, learning about things that repeatedly go wrong or could be improved on, or our problems. In addition to that, we wished to identify numbers, so that would be the numerator of how many cases occur in one year. 184 cases in those four countries in a year out of about three million anaesthetics, and about 60,000 patients intubation on intensive care, and 30,000 patients intubated in the emergency department. So we need to know activity as well, and that denominator came from a separate survey looking at how many cases were done in those locations, and how those airways were managed. And so what were your principal findings from the study?
The inclusion criteria for NAP4 occurred about 1 in 20,000 cases in anaesthesia, and 1 in 100,000 led to a death or brain damage. Within that, tracheal intubation was about four times as common in terms of events, four times as common as events with a supraglottic airway device with face mask ventilation cases being in the middle. And then in terms of deaths tracheal intubation was twice as common the primary choice compared to supraglottic airway devices. Of course the most difficult cases, the most complex cases, most of the critical illness cases are going to be managed with tracheal tubes, so it’s a slightly false comparison. Yeah. But those are the numbers. Those are the numbers.
And you were able to pick out some recurring clinical themes that are contributing to some of the complications. Could you summarise those? The major ones that grab you. So highlights– Yeah, the highlights. Highlights would be, for instance, failure to perform pre-operative assessment and to adjust the technique was a key component in particularly management of head and neck cases. Head and neck cases accounted for roughly half of all cases, and airway obstruction accounted for 70% of those cases. So patients who were having head and neck surgery and got airway obstruction are particularly high risk. We know this, but actually they also come to harm in spite of us knowing that.
A failure to identify patients who are at risk of difficult airway management or at high risk of aspiration was key, but perhaps more important than that a failure to change the anaesthetic plan, the airway management plan, to account for the identified problems was a recurrent theme. Failure to have a strategy, so more than one plan to manage the airway so that when problems occur that people could manage those. In terms of risk factors, there was an excess of obese patients that were reported to us. So at the time 24% of patients in the UK were obese in the population, and the surgical population was probably roughly the same.
But 45% of the patients reported in NAP4, so almost twice as many patients were reported in NAP4 who were obese than the general population. And if you take the morbidly obese– 2% of the population was morbidly obese in 8% of cases reported in NAP4, so that’s a fourfold excess of obese patients. And I think obesity is a– well, it’s clear from NAP4 that obesity is a huge risk factor. People often focus on difficult intubation and obesity.
I think that’s probably the least important issue, so difficult mask ventilation, failure of supraglottic airway device, difficult front of neck airway access, but particularly a limited time for oxygenation, and a limited time the patients will– a lack of, as it were, airway resilience when problems occur in the obese. So intensive care was an area of increased risk, and also an area of poorer performance. So if we compare intensive care to anaesthesia, the risk of a– if you consider a patient whose airway was managed in anaesthesia compared to a patient whose airway was managed in intensive care, you’re comparing apples and pears.
But there is a 60-fold greater risk of death or brain damage in intensive care than during anaesthesia, and if an event occurred in anaesthesia one in seven of those patients would suffer death or brain damage, whereas 60% of patients would die or suffer brain damage in ITU. The two areas which were particularly prominent were problems with tracheostomies, again, particularly in the obese. So a tracheostomy displacement, and difficult tracheal intubation as well. There were quite a few recommendations, but, again, could you summarise some of the main messages that you wanted to get through to the readers of the report? Yeah, that’s really difficult. Off the top of my head, I think there are 144 recommendations. Yeah, 168. 168? OK.
[LAUGHS] A lot of those recommendations are not anodyne, but they are descriptions of basic good airway care. And I don’t think we’d make any apology for having those in there, so seeing the patient making an assessment, making decisions based on what you find in the patient, making a plan or a series of plans of strategy, communicating. That’s all around. So if you perhaps were to focus on intensive care as a place of, as I’ve said, airway danger. We made strong recommendations that the right equipment was there, so the difficult airway trolley was available in all intensive cares. It existed in about 50% of intensive cares prior to NAP4. It now exists in more than 95% of intensive cares.
The individuals who were looking after intensive care at night were appropriately trained in basic airway skills. The checklists were used before all intubations on intensive care, and on, and on. There were algorithms for displacement of tracheal tubes, and algorithms for management of displaced tracheostomy tubes. And that capnography continued throughout the period of time that the patient relied on an artificial airway. Are there other things you’ve been able to gauge in terms of now, as you mentioned, nearly a decade on from the study to gauge the impact it has had in everyday clinical care. We did a quite extensive survey two years after NAP4, and we tried to identify what changes have been made.
And so one can divide the recommendations that were made into national recommendations, institutional, and individual recommendations, and we focused on the institutional recommendations. And we asked, do you comply with this recommendation, and did you make changes as a direct result of NAP4? In anaesthesia about 98% percent of organisations had made changes as a result of NAP4, and the safety gap had been closed by a median of about 50%. And in intensive care, where one could argue there was a greater need to make changes, about 80% of hospitals we identified had made changes, but the overall safety gap had closed by about 60%, and that was after two years. I’d like to think it’s changed more since.
We’re you surprised by any of the findings, and did the study affect your everyday practise? The key things that I learned or that changed my practise were understanding that I needed to have more coherently explicit plans, and that I should communicate those better. There’s that great quote, the single greatest problem with communication is the illusion it has taken place. George Bernard Shaw, and using you’re using your best equipment first up. Getting things right the first time I think is key. If you have the opportunity to use equipment, which means that you are likely to achieve success the first time, I think it makes sense to use that the first time. Professor Tim Cook, thank you very much.