Effective and timely airway management is a priority for sick and injured patients. The benefit and conduct of pre-hospital emergency anaesthesia (PHEA) and advanced airway management remains controversial but there are a proportion of critically ill and injured patients who require urgent advanced airway management prior to hospital arrival1 and the evidence shows us the benefits of this procedure when carried out with the appropriate training, education, robust competency framework and overarching clinical governance. It is a challenging procedure, and repeated attempts endotracheal intubation is associated with increased morbidity and mortality. It follows that this is a skill that should only be performed by appropriately trained and competent practitioners working in a properly structured prehospital system. This includes the mandatory use of standardised RSI checklists which have been proven to reduce cognitive load, eliminate individual practitioner variability, reduce error, and confirm availability of equipment, doses of drugs and failed intubation management plans.
Standards of practice and monitoring should be similar to those recommended for in-hospital anaesthesia.
Emergency anaesthesia is carried out to facilitate control of the airway and ventilation of critically ill patients. There are four broad indications for the procedure:
The decision to perform prehospital anaesthesia should be based on a thorough consideration of the RISKS vs BENEFITS to the individual patient. This should take into account:
|Factors in favour of on-scene intubation||Factors against on-scene intubation|
Time pressures in the pre-hospital environment mean practitioners rarely have the luxury of performing a comprehensive airway assessment. Tools such as the Aintree six-step approach to potentially difficult airways highlight the following important questions to ask prior to setting up for an RSI/DSI:
Additionally, cognitive aids such as the Airway Assessment chart displayed, take from The Vortex approach, provide a simple way of approaching an airway assessment.
Preoxygenation is vital for safe prehospital anaesthesia and should proceed through the entire preparation phase. A variation to RSI is that of DSI or Delayed Sequence Induction, which is generally described as the process of pre-oxygenation with sedation in advance of paralysis.
The table below illustrates a guide for the most appropriate form of preoxygenation for different patient groups as per their risk category:
Table 1: Risk categorization of patients during preoxygenation
Based on pulse oximetry whilst receiving high flow oxygen
Preoxygenation Period(3 minutes)
Onset of muscle relaxation(~ 60 seconds)
Apnoeic period(Variable duration dependent on airway difficulty, ideally <30 seconds)
Pre-drawn RSI drugs in standardised concentrations have been introduced as a means of reducing drug related errors.
Table of initial ventilator settings and tips for titrating
|Parameter||Normal lungs||ARDS/ALI||Asthma/COPD||Metabolic Acidosis||Head Injury||Severe obesity|
|Aim||Lung protective strategy||Recruitment, shunt retention, avoid atelectic trauma, achieve adequate oxygenation||Oxygenation, adequate exhalation avoiding breath stacking and volutrauma||Ensure adequate respiratory rate to maintain and even improve compensation for metabolic acidosis||Avoid reduced venous return by avoiding high intrathoracic pressures||Avoid atelectasis and shunting due to obesity|
|Position||20-30 degree head up unless hypotensive and reduced cerebral perfusion a concern|
|Mode||VC (SIMV)||VC (SIMV)||PC (APRV equiv.)||VC (SIMV)||VC (SIMV)||VC (SIMV)||VC (SIMV)|
|FiO2||Start at 100% and rapidly titrate down, ideally achieving FiO2 0.4. Avoid significant hyperoxia. Aim for oxygen saturations > 95%; pO2 >80. Aim Pplat <30.|
|Other||Adjust parameters to ensure O2 and CO2 within normal limits||Watch pressures; may need to lower Vt and accept higher CO2. Titrate FiO2 and PEEP||Minimise derecruitment||Minimise derecruitment, i.e. minimise suctioning and disconnection. Consider recruitment manoeuvres||Watch for breath stacking and volutramua or barotrauma. Consider permissive hypercapnia. pH >7.15. May need to accept higher peak pressures in asthmatics. Aim Pplat <30||Avoid high PEEP if possible. Aim PCO2 35-40. Tape rather than tie ETT to avoid impeding jugular vein flow.||Minimise decruitment, i.e. minimise suctioning and disconnections|
Christine M. Groth, Nicole M. Acquisto, Tina Khadem. Current practices and safety of medication use during rapid sequence intubation,Journal of Critical Care,Volume 45,2018,Pages 65-70,ISSN 0883-9441,https://doi.org/10.1016/j.jcrc.2018.01.017.
Brandon G. Santoni, Ph.D. ; Bradley J. Hindman, M.D. ; Christian M. Puttlitz, Ph.D. ; Julie B. Weeks, M.P.T. ; Nathaniel Johnson, B.S. ; Mazen A. Maktabi, M.D. ; Michael M. Todd, M.D.Manual In-line Stabilization Increases Pressures Applied by the Laryngoscope Blade during Direct Laryngoscopy and Orotracheal Intubation. Anesthesiology January 2009, Vol. 110, 24–31.https://doi.org/10.1097/ALN.0b013e318190b556
Jeffrey L. Jarvis, MD. 2016. Using DSI to Prevent RSI from Becoming RSD (Rapidly Sequenced Death). Williamson County EMS. http://txemsa.com/using-dsi-to-prevent-rsi-from-becoming-rsd
Manoach, Seth & Paladino, Lorenzo. (2007). Manual In-Line Stabilization for Acute Airway Management of Suspected Cervical Spine Injury: Historical Review and Current Questions. Annals of emergency medicine. 50. 236-45. 10.1016/j.annemergmed.2007.01.009.
Robitaille A, Williams SR, Tremblay MH, Guilbert F, Thériault M, Drolet P. Cervical spine motion during tracheal intubation with manual in-line stabilization: direct laryngoscopy versus GlideScope videolaryngoscopy. Anesth Analg. 2008 Mar;106(3):935-41, table of contents. doi: 10.1213/ane.0b013e318161769e. PMID: 18292443.