Segment taken from Anaesthetists Hymn
Here in Far North Queensland, Australia, we undertake a lot of psychiatric long distance fixed wing aeromedical retrievals. In fact the Top End or Far North of Australia, as a region, has more psychiatric aeromedical retrievals per annum than any other place on Earth as far as I am aware of. How many? Something of the order of 400-600 retrievals per annum for psychiatric cases alone.
So lately aeromedical research into this area has been increasing. I have published my work on ketamine sedation over the last 8 yrs with the work I do for Royal Flying Doctor Service. Other aeromedical services such as Careflight Darwin and MedSTAR of South Australia have published and expanded their own research . We have even worked on collaborative efforts to reach consensus towards a best practice standard in psychiatric aeromedical retrieval.
I had somewhat of an epiphany in my own thoughts and concepts in this work over the last month with undertaking several retrieval missions as well as auditing cases of colleagues.Also recent papers being published on emergency sedation have merged with my evolving concepts towards best practice in this challenging retrieval patient group.
I wish to share these latest thoughts via FOAMEd here!
- The aeromedical retrieval environment as a cause of agitation has been disrespected in the past. What do I mean here? It is my contention that aeromedical transfer of agitated patients has neglected the unique stressors that are placed on the patient. For example, noise , motion, vibration, ambient light, weather are all factors in possible increasing the agitation of a patient during transfer. How have we tried to mitigate these in the past? Very poorly in my opinion! Do we routinely ask agitated patients if they have a fear of flying? If they do, what do we do about it? Chemical sedation is often over used to reduce all these aeromedical stressors and this seems ill placed. For example in the ER or OT or ICU, we would never accept loud noise during a procedural sedation of a patient. Yet in aeromedical transport we put a sedated patient inside a metal box and turn on very loud noise for sometimes 1-2 hrs depending on the flight duration. Are we surprised that seemingly calm sedated patients on the ground, become more agitated inflight? Certainly if you use a sedative like ketamine, then we know that loud noise and other external stimuli can influence some dissociated patients to experience a bad ketamine trip. So I have begun to routinely place ear protection on all sedated patients during aeromedical transfer. You might be surprised this is not done as a standard thing but it has never been the standard , at least in fixed wing psychiatric retrievals. I believe it should become the minimum standard care for sedated patients during psychiatric aeromedical transfer. The next concept to consider will be auditory modulation of the sedated experience. For example using headphones to play calm, relaxing music to the sedated patient. This may well reduce chemical sedation requirements.
- Ketofol is a sedative combination that may well be the ideal for psychiatric aeromedical retrieval. Why? Over the years of research and clinical audit, it became clear to me and colleagues that although IV ketamine infusions had safely and dramatically reduced the need to resort to tracheal intubation and general anaesthesia for highly agitated patients requiring aeromedical transfer, there was a small cohort of patients who would get more agitated during the flight. It is clear to me now that this is due to the stimulating nature of ketamine on the frontal lobe combined with the unique stimuli of the aeromedical environment. In essence you need to somehow turn the frontal brain off, when this stimulation occurs during flight. Midazolam has traditionally been used to manage ketamine induced delirium. Whilst fine as a short acting agent for short term sedation with ketamine, for prolonged aeromedical flights it is less than ideal. Ketofol sedation performed as a baseline propofol infusion, with ketamine adjunctive boluses has worked well recently on a handful of retrievals in which inflight agitation was an issue. The key here is to run the propofol infusion at a low enough dose to turn off the frontal brain but not enough to cause respiratory compromise. Instead of increasing the propofol infusion or bolusing it, ketamine boluses are used instead to manage additional agitation. Before the ketofol strategy, we would routinely increase the ketamine infusion or give large boluses. Deepening ketamine dissociative anaesthesia will work eventually but often leads to longer recovery times after handover and may well not mitigate the bad ketamine trip experience.
- Gastric ultrasound and vomiting risk with sedation. A lot of EM literature suggests that fasting status and procedural sedation is not a major concern but caution needs to be taken in extrapolating it to the aeromedical setting. Psychiatric retrievals here often can take 1-2 hrs and this is not the short EM procedural sedation we might do to reduce a shoulder or remove a foreign body. The decision to intubate or do procedural sedation for aeromedical retrieval of an acutely agitated patient can be done more precisely by determining the vomiting risk of the patient prior to transport. The duration of transport, the appearance of a large amount of gastric content on ultrasound and the airway assessment of the patient are all important factors in making that decision. If ultrasound shows an empty stomach then the margin of safety of sedation from a vomiting and aspiration viewpoint is dramatically reduced.
Ketamine as Rescue Treatment for Difficult-to-Sedate Severe Acute Behavioral Disturbance in the Emergency Department
Incidence of Adverse Events in Adults Undergoing Procedural Sedation in the Emergency Department: A Systematic Review and Meta-analysis.