Nociception testing during fixed-wing ambulance flights. An interventional pilot study on the effects of flight-related environmental changes on the nociception of healthy volunteers

Abstract

27 28 Background: The effects of environmental changes on the somato-29 sensory system during long-distance air ambulance flights need to be 30 further investigated. Changes in nociceptive capacity are conceivable in 31 light of previous studies performed under related environmental settings. 32 We used standardized somato-sensory testing to investigate nociception 33 in healthy volunteers during air-ambulance flights. 34 Methods: Twenty-five healthy individuals were submitted to a test 35 compilation analogous to the quantitative sensory testing battery -36 performed during actual air-ambulance flights. Measurements were paired 37 around the major changes of external factors during take-off/climb and 38 descent/landing. Bland-Altman-Plots were calculated to identify possible 39 systemic effects.40 Results: Bland-Altman-analyses suggest that the thresholds of stimulus 41 detection and pain as well as above-threshold pain along critical waypoints 42 of travel are not subject to systemic effects but instead demonstrate 43 random variations.44 Conclusions: We provide a novel description of a real-life experimental 45 setup and demonstrate the general feasibility of performing somato-46 sensory testing during ambulance flights. No systematic effects on the 47 nociception of healthy individuals were apparent from our data. Our 48 findings open up the possibility of future investigations into potential 49 effects of ambulance flights on patients suffering acute or chronic pain.50 51 Introduction 52 Inter-hospital transfers are common medical procedures, that are 53 sometimes carried out using fixed-wing air-ambulances. The number of 54 such long-distance transfers is steadily rising due to the ongoing 55 internationalization of specialized medical care and, much more 56 importantly, due to increases in individual international mobility [1]. The 57 latter results in growing numbers of aeromedical retrievals of travelers 58 back to their home countries [2]. 59 Long distance air ambulance flights can be considered a medical field of 60 pre-requisites that truly distinguish it from intra-hospital care. While 61 vibrations, noise, and restricted patient access must also be considered in 62 other means of transportation, such as ground-ambulances and mobile 63 ICUs, the rapid alterations in atmospheric pressure, oxygen partial 64 pressure and air humidity that occur during airplane flights are 65 environmental changes that are actually unique to this mode of transfer. 66 Despite this distinctiveness, most in-flight medical measures are simply 67 extrapolated from what we know and do when on solid ground. For 68 example, during transfers, analgesia is typically applied as if the patient 69 were in a hospital -regardless of any of the possible effects, the profound70 environmental changes caused by flying in an airplane might have on 71 human nociception.72 Data from several studies have called this business-as-usual approach into 73 question. For example, Sato and colleagues found that neuropathic pain 74 was significantly ag...