Haemodynamic effects of a prehospital emergency anaesthesia protocol consisting of fentanyl, ketamine and rocuronium in patients with trauma: a retrospective analysis of data from a Helicopter Emergency Medical Service

Abstract

ObjectivesPrehospital rapid sequence induction (RSI) of anaesthesia is an intervention with significant associated risk. In this study, we aimed to investigate the haemodynamic response over time of a prehospital RSI protocol of fentanyl, ketamine and rocuronium in a heterogeneous population of trauma patients.Design, setting and participantWe performed a retrospective study of all trauma patients who received a prehospital RSI for trauma by a physician staffed Helicopter Emergency Medical Service in the UK between 1 June 2018 and 1 February 2020.Primary outcome measurePrimary outcome was defined as the incidence of clinically relevant hypotensive (systolic blood pressure (SBP) or mean arterial pressure (MAP) >20% below baseline, with an absolute SBP <90 mm Hg or MAP <65 mm Hg) or hypertensive (SBP or MAP >20% above baseline) episodes in the first 10 minutes post-RSI.ResultsIn total, 322 patients were included. 204 patients (63%) received a full-dose induction of 3 μg/kg fentanyl, 2 mg/kg ketamine and 1 mg/kg rocuronium, whereas 128 patients (37%) received a reduced-dose induction. Blood pressures decreased on average 12 mm Hg (95% CI 7 to 16) in the full-dose group and 6 mm Hg (95% CI 1 to 11) in the reduced-dose group, p=0.10). A hypotensive episode (mean SBP drop 53 mm Hg) was noted in 29 patients: 17 (8.3%) receiving a full dose and 12 (10.2%) receiving a reduced-dose induction, p=0.69. The blood pressure nadir was recorded on average 6–8 min after RSI. A hypertensive episode was present in 22 patients (6.8%). The highest blood pressures were recorded in the first 3 min after RSI.ConclusionPrehospital induction of anaesthesia for trauma with fentanyl, ketamine and rocuronium is not related to a significant change in haemodynamics in most patients. However, a (delayed) hypotensive response with a significant drop in SBP should be anticipated in a minority of patients irrespective of the dose regimen chosen.

The effect of ketamine and fentanyl on haemodynamics during intubation in pre‐hospital and retrieval medicine

“…In this cohort, fentanyl use was relatively uncommon, and the doses used were low in comparison to other published induction regimens. 21,23 There was no measurable impact of fentanyl use in the incidence of haemodynamic instability post-induction. The baseline characteristics of the two groups were similar, suggesting that other unmeasured factors such as clinician preference may be involved in the decision to use fentanyl.…”

“…Penetrating trauma 14 F I G U R E 2 Systolic blood pressure over time, by group limit of their first tertile being 1.24 mcg/kg, whereas the 75th centile dose in our study was 1.5 mcg/kg; this dosing discrepancy may explain the difference in our findings. Ter Avest et al also reported on a cohort of trauma patients receiving standardised dose regimens of fentanyl, ketamine and rocuronium, 23 noting a reduction in blood pressure, reaching a nadir at 6-8 min, regardless of standard or reduced dosing. The fentanyl doses used in this study were again in a higher range than in our cohort.…”

“…There is little consistency of haemodynamic endpoints in studies of truly emergency general anaesthesia 21,23,28 and we felt that the isolated use of a percentage deviation from baseline would fail to capture the nuance of clinical intention. Consequently, we defined our primary outcome as being met as follows:…”

“…21,22 Some services encourage fentanyl in varying doses for all patients induced with ketamine. 21,23 Greater Sydney Area Helicopter Emergency Medical Service (GSA-HEMS) utilises an SOP 24 that mandates the use of ketamine as a sedative agent for RSI but leaves the use of fentanyl to the discretion of treating clinicians. In this observational study we aim to describe the frequency of use and dosing of fentanyl in a system where its use is discretionary, as well as evaluating whether its use during induction is associated with improved postinduction physiology.…”

“…Addition of fentanyl to an induction regimen may also increase first‐pass intubation success, possibly due to a deepening of the plane of anaesthesia 21,22 . Some services encourage fentanyl in varying doses for all patients induced with ketamine 21,23 . Greater Sydney Area Helicopter Emergency Medical Service (GSA‐HEMS) utilises an SOP 24 that mandates the use of ketamine as a sedative agent for RSI but leaves the use of fentanyl to the discretion of treating clinicians.…”