Pre-Hospital Emergency Anaesthesia (PHEA)
“Unsuccessful or poorly conducted RSI can be life-threatening and may result in significant complications, such as oesophageal intubation, hypoxaemia, or post-induction cardiac arrest. The intervention therefore requires a high level of competence and the ability to manage any complications.”
This month’s episode is very much not a how-to PHEA podcast. This is designed to give a bit of awareness to what’s happening if you’re part of one and how you can support the wider team if you find yourself looking after a patient receiving an anaesthetic.
Which patients benefit from PHEA:
Impending obstruction- Actual or impending airway compromise (including protection and maintenance) airway swelling due to burns, anaphylaxis, significant airway bleeding, injury, neck haematoma.
Respiratory failure - Severely impaired and worsening ventilation and/or oxygenation which cannot be adequately managed.
Neuroprotection - Pt's who are severely agitated and unmanageable may require PHEA to stabilise and facilitate onward transfer. Patients requiring airway or ventilation protection to minimise secondary brain injury.
Anticipated clinical course - If the predicted clinical course of the patient would requires RSI on arrival at ED to facilitate ongoing investigation or treatment, PHEA may expedite the transit to definitive care albeit at the expense of potentially prolonging on scene times. Also where the patient is expected to deterioraterapidly or when intubation and ventilation will have a major impact onexpediting life-saving intervention at hospital
Humanitarian – to relieve severe pain, distress or suffering in the severely injured patient which cannot be safely managed through other means.
The Pharmacology of PHEA:
Analgesia: - fentanyl to blunt laryngeal reflex
Ketamine: - Anaesthetic (turn off the brain)
Roc – Neuromuscular Blocker (paralytic) Reversal and quick offset not needed, if you’re doing it…you’re doing it.
Vasopressors – risk of hypotention from drugs, sympathetic depression, after drop from ventilator.
- Standard RSI drugs – Fentanyl/ Ketamine/ Rocuronium (3:2:1) – 3mcg/kg Fent, 2mg/kg Ketamine and 1mg/kg of roc. If obtunded or hypovolemic and at risk consider a 1:1 approach so lower dose ketamine + rocuronium.
- Ketamine disproven to raise ICP so fine in TBI.
Ketamine is a dissociative anaesthetic that works by blocking NMDA receptors. Dose is 1-2mg/kg for anaesthesia. 45 to 60 seconds onset time and duration of action is 10-20 mins. Preivously believed that ketamine raised ICP and was therefore not used for TBI inductions however this has largely now been disproven and is widely used for this indication, especially prehospitally. It has also be shown to have some potential bronchodilator effects so might be useful in asthmatic patients undergoing anaesthesia.
Contraindications include – known hyper sensitivity/ allergy.
Adverse effects that warrant consideration include hypertension and tachycardia so should be used in caution in those with cardiovascular diseases where we don’t want to increase myocardial oxygen demand. Laryngospasm very rare but possible should be managed by drilling laryngospasm complications when critical care teams train and simulate.
Rocuronium – non depolarising neuromuscular blocker. It works by blocking acetycholine from binding to post synaptic motor receptors and preventing depolorisation, leading to paralysis. Onset of action is around 60 seconds and duration of action 60-90 mins. Dosing is normally 1.2mg/kg
Performing procedure:
PREPARATION
Location:
360 degrees - consider the team may choose to perform the proceedure outside verses in truck. Other considerations are weather protection, privacy, light, safety Vs 360 access, height and positioning, sufficient space
Weather - Not just rain..light level, temperature are all factors. Bright light can often be problematic when it comes to intubation. Back to sun means its not in your eyes for intubation, but is then shining on display screens, creating a shade for the team on the airway is very helpful.
Confidentiality and privacy - be aware of “HEMs spotters”, press, onlookers etc.
Noise
Pre-oxygenation: no reason a crew cannot begin this process with NRB, Assist vent and/or apnoea oxygenation
Stabilisation of haemodynamic instability: Fluids cautiously, Saline not as evil as we thought. Aim for radial and 90mmHg in blunt trauma, central and 60mmHg in penetrating trauma. TXA if indicated prior to crit care arrival.
Equipment: You can support the kit dump before the team arrive as this is what take the time.
T - Two O2 cylinders
U - Undress (the patient, not the critical care team)
B - Bilateral large bore IV access
E - Ensure 360 degree access
S - Suction x 2
Positioning:
On bed trolly bed, 1st view needs to be best view. Planning to take patients airway away, therefore need to maximise chance of first pass success.
Option for head up ( head injury, improve view, obesity)
Practically never done on the floor. Moving to bed is really useful and MUST be done. Very useful if crew have this already done.
Monitoring:
AAGBI must have BP every 3 mins, spo2, etco2, ECG, HEMS crew will want their own for CG. Prepare to swap over after handover… can be useful to pre-alert your ECA this will happen. Think about it when applying your monitoring in the first instance to make it easier.
Role allocation:
Operator 1 - doing tube, airway assessment, head positioning, height, tube size, plan
Operator 2 - kit dump
Cricoid/ELM Operator - As we discussed in the podcast, here’s the video discussing cricoid pressure.
C-Spine – amended position, need to account for laryngoscope.
Team leader – checklist reader,
Airway:
PLAN A , B ,C D , [DAAS algorithm, or VORTEX.] may be non-linar.
Difficult airway predicted may decide to Mark up anatomy for FONA
Breathing:
Pre-oxygenation + Apnoic oxygenation - denitrogenation - deadspace 1/3rd TV or 150ml in adults. High flow o2 to oxygenate this. During apnoea, PP from high flow nasal specs can continue to fill alvioli and provide PP to encourage oxygen uptake. Rudlof and Hohenhorst (2013) demonstrated safe apnoea times of 40 + minutes in healthy adults. obviously less apnoea time in obese or critically unwell pts who may have shunt. Useful for crews to put it on. If pt GCS 15/15, nasal specs on but perhaps not flowing. [3] [http://vortexapproach.org/apox/]
DSI for agitation - delayed sequence intubation Post- ROSC most common, small amount of sedation to facilitate pre-ox and to optimise physiology prior to induction.
Example of a kit dump
Circulation:
2x IV access
May need an I/O, not always though, clinical situation dependant.
Fluids running not on BP arm… slow running, demonstrates patency, can be opened up fully incase of hypotensive episode. May need filling pre-PHEA
Kit DUMP :Operator 2. Needs space, needs ownership Done away from the scene, bring pt to kit. Avoids issues with losing kit. = tidy
Brief:
10 for 10, heads in ensure everyon is on the same page and discuss induction plan.
induction plan
Check list:
discuss how they’re used in aviation
Not a check and do list
Check and response
Slow down
If something is missed, move back to last known correct thing CRM , aviation ensures nothing missed.
Quiet please! – sterile cockpit
Drugs in:
60-90 seconds for Roc. Looking for apnoea, jaw laxity
Laryngoscopy – talking through view, improve situational awareness for the team.
Post PHEA check list
ensure that nothing is missed in preparing this patinet for transport
Scene momentum: - real risk scene momentum is lost. Crews can be very helpful, once tube secure help to begin packing up. Help to keep time pressure on. There should be no reason why we aren’t moving toward hospital.
Take away points
Take away points
Not a podcast about how to perform a PHEA, nor is it a podcast about the merits of varying anaesthetic regimes. That isn’t our sphere of expertise. This is a podcast designed to give an understanding of why patients might receive a pre-hospital anaesthetic. What crews are likely to observe and why things are done in a certain way. And How crews can help and support the team.
PHEA is a team game. The road crews are an essential part of that and perhaps are the most influential cog in helping it to run smoothly.
Preparing for PHEA is what takes the time, so any prep you’re able to do before hand is particularly helpful. Remember “TUBES” Two oxygen bottles Undress the patient Bilateral IVA access Ensure 360 degree access Suction x 2. Think about the environment we’re going to perform the procedure, well lit, but not in brigh sunshine, protected from the elements, with smooth access and egress for a trolly bed, is essential.
Loss of momentum post PHEA is a real risk. Help to keep the teams foot on the gas, and once the procedure is complete, everyone needs to be helping to move towards definitive care. and finally, don’t forget that you are an essential member of the team, working to keep the patient safe. Support the critical care team with creating the optimum environment to perform an anesthetic, help to create a sterile cockpit by ensuring speech is limited to the procedure, but don’t be afraid to speak up if you think you see a problem or a safety issue.
Remember, clinicians are responsible for their own practice. These podcasts are produced for informative purposes and should not be considered solely sufficient to adjust practice. We provide lots of learning resources, so don’t just take our word for it…navigate to these and reflect on this topic further. See "The Legal Bit" for more info.
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references
1 - https://das.uk.com/guidelines
2 - http://vortexapproach.org/
4- https://academic.oup.com/bja/article/113/2/211/264336?login=false ‘
5 - https://www.magpas.org.uk/wp-content/uploads/2018/02/SOP-6.0-PHEA-2018.pdf