Abstract
BackgroundPrevious studies have demonstrated an association between hyperoxia and increased mortality in various patient groups. Critically unwell and injured patients are routinely given high concentration oxygen in the pre-hospital phase of care. We aim to investigate the incidence of hyperoxia in major trauma patients receiving pre-hospital emergency anesthesia (PHEA) in the pre-hospital setting and determine factors that may help guide clinicians with pre-hospital oxygen administration in these patients.MethodsA retrospective cohort study was performed of all patients who received PHEA by a single helicopter emergency medical service (HEMS) between 1 October 2014 and 1 May 2019 and who were subsequently transferred to one major trauma centre (MTC). Patient and treatment factors were collected from the electronic patient records of the HEMS service and the MTC. Hyperoxia was defined as a PaO2 > 16 kPA on the first arterial blood gas analysis upon arrival in the MTC.ResultsOn arrival in the MTC, the majority of the patients (90/147, 61.2%) had severe hyperoxia, whereas 30 patients (20.4%) had mild hyperoxia and 26 patients (19.7%) had normoxia. Only 1 patient (0.7%) had hypoxia. The median PaO2 on the first arterial blood gas analysis (ABGA) after HEMS handover was 36.7 [IQR 18.5–52.2] kPa, with a range of 7.0–86.0 kPa. SpO2 pulse oximetry readings before handover were independently associated with the presence of hyperoxia. An SpO2 ≥ 97% was associated with a significantly increased odds of hyperoxia (OR 3.99 [1.58–10.08]), and had a sensitivity of 86.7% [79.1–92.4], a specificity of 37.9% [20.7–57.8], a positive predictive value of 84.5% [70.2–87.9] and a negative predictive value of 42.3% [27.4–58.7] for the presence of hyperoxemia.ConclusionTrauma patients who have undergone PHEA often have profound hyperoxemia upon arrival at hospital. In the pre-hospital setting, where arterial blood gas analysis is not readily available a titrated approach to oxygen therapy should be considered to reduce the incidence of potentially harmful tissue hyperoxia.
Highlights
Previous studies have demonstrated an association between hyperoxia and increased mortality in various patient groups
Patient characteristics pre-hospital emergency anesthesia (PHEA) was performed in 1241 patients during the study period, 432 patients were subsequently admitted to St George’s Hospital (STGH). 285 fulfilled the inclusion criteria. 76 patients were excluded
Patients with hyperoxemia in their arterial blood gas analysis (ABGA) generally presented to the Helicopter emergency medical services (HEMS) team with a higher median Glasgow Coma Score (GCS) before they were intubated, they had less often an oxygen desaturation peri- or post intubation, and had a higher pulse oximetry S pO2 on the HEMS monitor at handover in hospital
Summary
Previous studies have demonstrated an association between hyperoxia and increased mortality in various patient groups. Helicopter emergency medical services (HEMS) are frequently dispatched to patients after major trauma, since they can deliver specific, advanced clinical interventions that land ambulance crews are unable to Leitch et al Scand J Trauma Resusc Emerg Med (2021) 29:134 provide. Examples of these include thoracostomies to relieve a tension pneumothorax, the transfusion of blood products to treat ongoing blood loss, and pre-hospital emergency anesthesia (PHEA) to definitively manage the airway or to optimise ventilation. Previous studies have demonstrated an association between hyperoxia and increased mortality in patients following cardiac arrest, sepsis, stroke and traumatic brain injury (TBI) [8,9,10,11]
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