Tag Archives: Safety

NAP4 and its implications for prehospital airway management

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In 2011 the U.K. Royal College of Anaesthetists and The Difficult Airway Society released a report called NAP4 – the 4th national audit of major complications of airway management.

Full text of NAP4 report

Full text of NAP4 report

The report covered airway complications that occurred in anaesthesia, ICU, and ED settings (approximately 20000 in total). Every reported complication of airway management was analysed for causes and learning points.

The findings relating to ED complications have direct implications for prehospital airway management.

‘Take-home’ messages relating to ED airway management:

  • in the event of an airway complication (most commonly failed RSI), patients were more likely to die in ED or ICU than OR
  • at-risk patients were often not identified prior to the attempt at airway management
  • waveform quantitative capnography should be the standard of care for EVERY intubation
  • situations where the capnography reading was zero (indicating misplaced or completely obstructed ETT) were incorrectly attributed to cardiac arrest (CPR always generates SOME CO2)
  • complications arose when there was a ‘failure to plan for failure’
  • obesity was a major risk factor for airway complications

and, most importantly:

  • in the event of a surgical airway being needed, surgical cricothyroidotomy was almost universally successful, while needle cricothyroidotomy had a failure rate of up to 60%
  • the success of surgical cricothyroidotomy included those where ED doctors (not surgeons) were the ones performing the procedure

Here is an excellent podcast – it is an interview by Cliff Reid of Jonathan Benger, a Professor of Emergency Medicine and one of the authors of the NAP 4 study (sourced from emcrit.org) regarding the implications of NAP4 for emergency department airway management.

So what are the implications for our HEMS service?

The most relevant findings for us form NAP4 are the findings relating to airway complications in ED, more so than anaesthesia or ICU. Patients who we would intubate pre-hospital are those who, if prehospital intubation were not available, would be intubated shortly after arrival in ED. The majority of our doctors are ED-trained, and are most familiar with ED airway management (translation: simple, fast, relatively low-tech, with the fairly standardised approach for the majority of our patients)

Bringing ED airway management to the prehospital arena has its challenges. The patients are more undifferentiated, comparatively under-resuscitated, and there may not have been enough time to get a sense of their ‘trajectory’.Environmental  factors (light, weather, physical access to patient) will have a huge impact on the execution of airway intervention.  We have a lot less equipment – no Glidescope, less rescue devices, and no telephone to call for an anaesthetist and a tech with a trolley full of difficult airway equipment. We may have team members (relatively junior ambulance staff, for example) who have much less experience with RSI than ED nurses who are often part of our RSI team.

Doing the basics right therefore becomes even MORE important:

  • equipment must be effective, functional, and familiar to us through training
  • there must be a ‘shared mental model’ – including a plan for success and a plan for failure – which must be vocalised for every patient with all team members understanding their role
  • we must actively consider patient specific elements that will affect the plan for success and the plan for failure (anatomy, injury, obesity etc)
  • we must be as prepared as possible – if the situation allows, taking several extra minutes to optimise positioning, place nasal cannulae for apnoeic ventilation etc may be crucial
  • we can overcome the disorienting effect of unfamiliar/unfriendly environments by using our RSI checklist – this was we are unlikely to forget something crucial (like capnography)
  • there must be a relatively ‘hands off’ team member whose task is to maintain situational awareness – in particular to initiate the ‘plan for failure’ should it become necessary
  • in the event of ‘can’t intubate, can’t ventilate‘, a surgical cricothyroidotomy should probably be our ‘go-to’ surgical airway of choice. If needle cricothyroidotomy has a failure rate of up to 60% in a hospital setting, it is hard to imagine how it could fare better in the prehospital arena. Of course there may be exceptions to this (difficult neck anatomy etc)

More commentary on the results and implications of NAP4 can be found here (British Journal of Anaesthesia, section of report relevant to ED and ICU) and here (from Cliff Reid)

 

HEMS: Lessons from Helicopters to Fast Response Cars

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This video shows a superb talk by Dr Gareth Davies, Clinical Director of the London HEMS. Topics covered include the role and structure of the service, the risks involved, and how those risks are mitigated with lessons learned from aviation.

This video comes from Risky-Business.com, a collaboration between various UK and USA hospitals and institutions which focuses on risk management and human factors in the medical setting.

Click here to watch the video.

Summer in New Zealand

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The New Zealand summer runs from December to February inclusive. At midnight on the 30th of November, the following rules come into effect:

1) the entire population must spend as much of the summer at the beach as possible

2) Living in New Zealand for more than three days qualifies you to operate a powerboat or yacht

3) alcohol hones your water safety skills and judgement

4) wearing life jackets, using fins with your bodyboard, swimming between the flags, and using dive decompression tables are all signs of weakness

Here is someone from Christchurch who clearly believes rules 1,2,3, and part of 4:

With these rules in mind, here are some slide sets regarding pathology that we may have to deal with over the summer:

Key issues for Auckland HEMS:

1) The hyperbaric chamber is at the Devonport Naval Base. They have minimal medical equipment and DO NOT have the capability to receive critically ill patients directly from the prehospital setting (I have discussed this with them before!). Critically ill patients will require transport to hospital with a subsequent trip to the decompression chamber.

2) our helicopter is not pressurised – transportation of patients with DCS or AGE should occur below 1000 feet of altitude

The contact number for the decompression physician (24 hours) is 0800 4 DES 111

Patients with submersion injuries may have been treated by Surf Lifesaving New Zealand. A link showing the tiers of Surf Lifesaving prehospital medical care is here. They may have access to AEDs, oxygen, monitoring, and cervical collars, but do not generally have access to advanced airway management.

Delayed sequence intubation, apnoeic ventilation, and preventing desaturation (plus podcast)

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‘Delayed sequence intubation’ and ‘apnoeic ventilation’ are two of the hottest topics in ED airway management at the moment. Details and discussion of these topics are all over the internet currently (multiple links coming below!) so what I will provide now are BRIEF summaries of the concepts.

The relevance to our HEMS is that both of these techniques for delaying the time to desaturation during intubation should (in theory!) translate well to the prehospital environment, and provide additional weapons in the prehospital airway management arsenal.

Traditional Rapid Sequence Intubation involves:

1) a period of pre-oxygenation

2) simultaneous administration of an anaesthetic induction agent and a paralytic

3) intubation once sedation and paralysis is adequate

The problem with rapid sequence induction in the ED setting is that the sicker the patient is, the quicker they will desaturate once they are paralysed, and the less time the intubating clinician has to pass an ETT. This is the case particularly in patients with severe lung disease.

So how can we give ourselves longer to pass the ETT before the patient desaturates?

Apnoeic ventilation, the evidence behind it, and other significant considerations in intubation are described in this landmark paper by Scott Weingart (emcrit.org) and Richard Levitan (airway guru). They make the following points:

1) pre-oxygenation using non-invasive ventilation will recruit collapsed alveoli and provide more of a reservoir of oxygen in the lungs – especially useful in high risk patients, or those who are hypoxic to start with

2) prexoygenation provides a longer time to desaturation when the patient is sitting up

3) during the apnoeic period (after the administration of a paralytic) doing a jaw thrust will maintain a patent connection between the mouth and the glottis, and the patient will continue to oxygenate (although CO2 will rise)

4) having a nasal cannulae running at 15L/min during the apnoeic period (after a paralytic has been administered) will provide near 100% oxygen to the pharynx

(Items 3 and 4 above comprise APNOEIC VENTILATION)

4) during the apnoeic period, having the patient positioned with their ear at the same level as their sternum will provide the best view for laryngoscopy

DELAYED SEQUENCE INTUBATION is described in this paper by Scott Weingart. It is an unfortunate fact that many of the patients who most desperately need effective preoxygenation (hypoxic, hypercarbic) are unable to receive it because they are too agitated and combative.

One of the models Dr Weingart uses to describe DSI is “a procedural sedation, the procedure in this case being effective preoxygenation”.

The DSI procedure involves administering ketamine (chosen for its safety profile and preservation of airway reflexes and spontaneous respiratory effort) at a dose of 1-1.5kg, followed by pre oxygenation (with consideration of NIV pre oxygenation), followed by administration of a paralytic and intubation.

This podcast from prehospitalmed.com is a great interview of Scott Weingart by Minh Le Cong, discussing DSI in detail.

Minh Le Cong has also collated some resources regarding DSI here, including a formal protocol incorporating DSI and apnoeic ventilation and a detailed slide set from Dr Rob Bryant, Emergency Physician in Salt Lake City, Utah (note – decision-making regarding suitability for intubation/ICU admission is clearly different in the northern hemisphere!)

Aided greatly by the internet, these techniques have “gone viral” amongst emergency physicians and are being used with success in the ED setting. They are also making their way into the prehospital world.

With regards to the Auckland HEMS, the following considerations may be relevant:

1) For patients with lung disease, fitting a PEEP valve will allow delivery of CPAP pre oxygenation. In the setting of trauma and potential pneumothorax however, there may be significant risks

2) A jaw thrust during the apnoeic period and adminstering O2 at 15L/min via nasal cannulae are easy interventions prehospital. Given that all our prehospital RSIs to date have occurred at scenes with St John’s ambulance already in attendance, we are highly likely to have additional oxygen sources available for apnoeic ventilation beyond what we carry in the helicopter

3) While delayed sequence intubation has been described for patients with agitation due to hypoxia, there is no reason we can’t use it for patients with agitation due to other causes, for example the intoxicated patient with a moderate TBI. Even in the ED setting these patients are difficult to intubate, with a traditional RSI typically requiring multiple security guards/orderlies, and a rather desperate ‘quick and dirty’ one!  The particular relevance to HEMS is that the DSI procedure is targeted at the patient group (agitated, combative)  who are probably the WORST group to transport in a helicopter without intubating them (cramped environment, difficult ergonomics for restraint/sedation, more difficult monitoring, lots of equipment/emergency exists in close proximity…)

There are some caveats to us adopting these techniques however, especially DSI. The prehospital evidence base currently is (probably!) nil. In the podcast above, pod Scott Weingart describes his concern that someone will modify the DSI procedure (either via drugs or technique), cause a catastrophe, and ruin DSI’s reputation forever. Certainly there is significant concern from some anaesthetists who feel that the concept is “crazy”.

Prehospital RSI remains a controversial topic, mainly because the evidence base that it is beneficial is small compared to the evidence base that done badly it worsens outcomes (great summary of these issues in a slide set here by Tony Smith, one of our HEMS doctors who is both an intensivist and the medical advisor to St Johns ambulance).

Auckland HEMS trains extensively in RSI to ensure that it is safe and effective. St John’s Ambulance also have a good understanding of the procedure, with the result being that they can be valuable assistants when we perform an RSI. They also share with us the ‘mental model’ of what we are doing and why we are doing it. If we attend a scene, attempt the novel and relatively unproven DSI procedure based on good sense but little evidence, and have a poor outcome, we would probably be judged fairly harshly.