(Part Three of an evidence review by Jamie Todd)
The recommended procedure in many other guides and systems is for a surgical approach to establishing an airway in these can’t ventilate, can’t oxygenate scenarios (Difficult Airway Society, 2018) where a surgical incision is made to the cricothyroid membrane and culminating through various intermediate taught techniques and slightly varying equipment with a cuffed endotracheal tube being placed into the trachea. (Bosanko, 2018)
The known advantages of this technique are; Cost, as in its simplest form the only expense is a Size 10 disposable scalpel as the other equipment is already in Pre-Hospital Care Endo-Tracheal Intubation kits; Familiarity, the simplest form of this procedure is often advocated (Difficult Airway Society, 2018) as there is no complex technique or equipment to remember, in my anecdotal experience once someone has the principles of the technique the skill fade although present is far less than other complex techniques; Speed, in probably an already hypoxic patient the time taken OR time taken to convert a failed other technique into a surgically performed airway may be significant in patient outcomes (Crewdson & Lockey, 2013); Safety, in its simplest technique when well done the scalpel is contained in a relative safe zone, almost no force is required and the use of the bougie can prevent the false positive insertion feel of the short tube trochar devices; Effectiveness, obviously the placement of a reasonable size (Usually 6mm Internal Diameter) Endo-tracheal tube allows for near to normal ventilation with relatively low ventilation pressures and reduces the need for further procedures to exchange the device based tubes for something larger.
Establishing success rates of the procedure can like the others be difficult to determine due to a variety of operators, techniques and situations reported in studies again with very low numbers. Many papers though suggest an average success rate in excess of 90% although this does often not translate into patient survival as these patients are often in extremis with severe injuries. (Davies, 2018) (Langvad, 2018) Of particular interest given the situation and the fact that mostly Paramedic level or none specialist physicians were involved is the reported data from 8 years of the British Forces medical personnel in Afghanistan obviously working in a more than harsh clinical environment under intense stress. Under these arduous conditions using a simple surgical technique a success rate of 92% was reported (Tony Kyle, 2016). Another recent UK paper involving UK Critical Care Paramedics reviewed the number of Surgical Airways performed in a UK ambulance service in a four-year period. Initially this paper raised a few eyebrows due to the numbers of procedures reported seemed high compared to no real data but to people’s expectations from routine anaesthesia (MacDougall-Davis, 2018) and I admit that included myself but on reflection may this be more that this cohort were recognising and managing airway issues a known cause of death particularly in trauma (NCEPOD, 2018). The data from this paper shows a success rate defined as ventilation through a surgically inserted Endo-Tracheal tube for this group of clinicians as very favourable 97% (Bell, 2017) with insertion times averaging 1 minute.
Complication for a surgical approach through the cricothyroid membrane appear low with low failure rates and controllable by compression site of incision bleeding being reported as the main issues (Davies, 2018) (Langvad, 2018)