Estimated reading time 5 minutes, 57 seconds.
How high is the potential risk from released droplets by infectious patients for the helicopter crew? Do pathogens spread from the cabin into the cockpit? These questions are not only highly relevant during the coronavirus pandemic: transporting patients with highly infectious diseases like influenza, tuberculosis or meningococcus is also playing an increasingly great role at DRF Luftrettung. Back in the autumn of 2019, DRF Luftrettung addressed this topic and started a scientifically-accompanied field test in cooperation with the German consulting centre for hospital epidemiology and infection control (BZH) in Freiburg. The findings from this study enable initial conclusions about transmission pathways to be drawn, which the hygiene management team at DRF Luftrettung can use to build on.
Within the scope of the project, a total of 16 test runs were performed on board the H145 and the EC135, 11 of which were on the ground and five in the air. Two scenarios were essentially depicted, and diversified within the course of the study. One of these was a worst case scenario, simulating a major pathogen release, and the other depicted an alternating, less extreme pathogen release. An oxygen nebuliser level with the patient’s head was used to recreate the droplets being released. The test simulated a droplet release like that which would occur if the spontaneously breathing patient or person coughed or sneezed in the cabin, as well as on the basis of the (intentional or accidental) disconnection of a breathing tube. Air flows were detected by means of fluorescence, and thus also the movements of the droplets. Their spread was made visible with UV light. The tests were carried out both with and without a curtain dividing cabin and cockpit in order to be able to draw conclusions about if and to what extent pathogens spread into the cockpit from the cabin.
Generally speaking, the tests indicated that with a spontaneously breathing patient there is a risk of pathogens not only spreading in the cabin, but also in the cockpit. The probability of infection depends on various factors like the type of pathogen, the transmission pathway and the exposure time. In the worst case scenario, i.e. a massive emission of droplets, there was a high probability of the pathogens not just settling on the surfaces in the entire cabin, but also spreading to the cockpit if there is no dividing curtain.
In the presence of a curtain, the particles landed on it. During the second test, with a short droplet emission which is equivalent to a cough or brief separation from a breathing tube in real life, there were deposits around the patient but not in the cockpit. This implies that the duration of droplet release determines the range and the degree of contamination. Variables such as ventilation settings for heating or air conditioning, flight direction or flight manoeuvres were also taken into consideration.