Pre-hospital / EMS / Out of Hospital
How often to patients desaturate during pre-hospital induction of anaesthesia? A retrospective review of rapid sequence intubation by a united kingdom based helicopter emergency medical service.
A. S. Al-Rais1, S. Taylor2, D. Bootland3 and M. Nelson3
1 Anaesthetic Registrar, London and HEMS Registrar, Kent, Surrey and Sussex Air Ambulance Trust, UK.
2 HEMS Paramedic, Kent, Surrey and Sussex Air Ambulance Trust, UK.
3 Consultant in Emergency Medicine, Brighton and Sussex University Hospitals Trust and HEMS Consultant, Kent, Surrey and Sussex Air Ambulance Trust, UK.
Introduction
Pre-hospital anaesthesia is well established throughout the UK and aligned to the same standards expected for in-hospital emergency anaesthesia. Yet rapid sequence intubation (RSI) outside of the operating theatre is associated with higher rates of complication; of which hypoxia is one . Hypoxia is a cause of increased morbidity amongst the critically ill, and even transient hypoxia has been shown to worsen morbidity and mortality, especially in head injured patients.
There have been several single centre publications from the UK and globally that place the incidence of an episode of desaturation during pre-hospital RSI in the region between 10.9% and 22.6%.
One of the risk factors likely to be associated with desaturation is inadequate pre-oxygenation prior to intubation. A recent survey of UK HEMS services found pre-oxygenation practices to be widely variable. Our service currently pre-oxygenates with 15 litres of oxygen via a reservoir mask.
We performed a retrospective review of RSI's within our UK HEMS service over a 12-month period. Our aims were to quantify our incidence of desaturation during pre-hospital RSI; to identify patient groups at greater risk of desaturation and to establish whether there is any remit to examine other methods of pre-oxygenation.
Methods
A retrospective single centre cohort review of Rapid Sequence Intubations from December 2016 to December 2017. Data was collected from our electronic patient record system (HEMSBase). An episode of desaturation was deemed to have taken place if the SpO2 fell below 92% or dropped by more than 10% in the 5 minutes after administration of Rocuronium.
There were 269 Rapid Sequence Intubations performed during the study period, of which 205 had records that contained sufficient data for analysis..
Results
30/205 (14.6%) of patients had an episode of desaturation during the peri-intubation period.
12/30 (40%) patients in the desaturation group had a chest injury versus 37/175 (21%) in the no desaturation group.
14/30 (46%) patients in the desaturation group were aged 60 or over versus 47/175 (26%) in the no desaturation group.
Conclusion
The incidence of peri-intubation desaturation in our service is in keeping with previously published data.
There is a remit for examining other methods of pre-oxygenation in order to reduce the incidence of desaturation.
Patients with chest injuries and the elderly are more likely to desaturate in the peri-intubation period.
