Background: During the COVID-19 pandemic in The Netherlands, critically ill ventilated COVID-19 patients were transferred not only between hospitals by ambulance but also by the Helicopter Emergency Medical Service (HEMS). To date, little is known about the impact of helicopter transport on critically ill patients and COVID-19 patients in particular. This study was conducted to explore the impact of inter-hospital helicopter transfer on vital signs of mechanically ventilated severe COVID-19 intensive care patients, with special focus on take-off, midflight, and landing.
Methods: All ventilated critically ill COVID-19 patients who were transported between April 2020 and June 2021 by the Dutch ‘Lifeliner 5’ HEMS team and who were fully monitored, including noninvasive cardiac output, were included in this study. Three 10-minute timeframes (take-off, midflight and landing) were defined for analysis. Continuous data on the vital parameters heart rate, peripheral oxygen saturation, arterial blood pressure, end-tidal CO2 and noninvasive cardiac output using electrical cardiometry were collected and stored at 1-minute intervals. Data were analydzed for differences over time within the timeframes using 1-way analysis of variance. Significant differences were checked for clinical relevance.
Results: Ninety-eight patients were included in the analysis. During take-off, an increase was noticed in cardiac output (from 6.7 to 8.1 Lmin-1; P<0.0001), which was determined by a decrease in systemic vascular resistance (from 1068 to 750 dyne·s·cm−5, P<0.0001) accompanied by an increase in stroke volume (from 92.0 to 110.2 ml, P<0.0001). Other parameters were unchanged during take-off and mid-flight. During landing, cardiac output and stroke volume slightly decreased (from 7.9 to 7.1 Lmin-1, P<0.0001 and from 108.3 to 100.6 ml, P<0.0001, respectively), and total systemic vascular resistance increased (P<0.0001). Though statistically significant, the found changes were small and not clinically relevant to the medical status of the patients as judged by the attending physicians.
Conclusions: Interhospital helicopter transfer of ventilated intensive care patients with COVID-19 can be performed safely and does not result in clinically relevant changes in vital signs.
This study was assessed by the medical ethical committee Arnhem-Nijmegen, the Netherlands (identifier 2021-7313). The committee waived the need for informed consent. The study was registered at www.trialregister.nl (identifier NL9307).