Cardiac Autonomic Activity in Commercial Aircrew During an Actual Flight Duty Period

Abstract

BACKGROUND: The work schedules of airline crewmembers include extended workdays, compressed work periods, and limited time for recovery, which may lead to cardiovascular strain and fatigue. The aim of this study was to evaluate changes in heart rate variability (HRV) during work and sleep, and with respect to work characteristics and breaks.METHODS: We followed 49 airline crewmembers during four consecutive workdays of ≥39 h. Data included HRV measurements, a questionnaire, and sleep/work diaries. HRV parameters include root mean square of successive differences (RMSSD), standard deviation of the normal beat-to-beat differences (SDNN), and the low and high frequency ratio (LF/HF).RESULTS: The results indicate higher levels of cardiovascular strain on the 4th compared to the 1st workday, most prominent among cabin crewmembers. In this group, we observed indications of decreased cardiovascular strain by increasing duration of sleep, demonstrated by increased RMSSD (B = 2.7, 95% CI 1.6, 3.8) and SDNN (B = 4.4, 95% CI 3.0, 5.7), and decreased LF/HF (B = −0.2, 95% CI, −0.4,−0.01). Similarly, longer duration of breaks was associated with lower cardiovascular strain, indicated by increased RMSSD (B = 0.1, 95% CI 0.03, 0.1) and SDNN (B = 0.1, 95% CI 0.1, 0.1). Among pilots, increased LF/HF indicated higher cardiovascular strain in those who often or always reported of high workload (B = 4.3, 95% CI 2.3, 6.3; and B = 7.3, 95% CI 3.2, 11.4, respectively).DISCUSSION: The results support the contention that the studied work period increases cardiac strain among airline crew. Work characteristics, breaks, and sleep are associated with changes in HRV.Goffeng EM, Nordby K-C, Tarvainen M, Järvelin-Pasanen S, Wagstaff A, Skare Ø, Lie J-A. Cardiac autonomic activity in commercial aircrew during an actual flight duty period. Aerosp Med Hum Perform. 2019; 90(11):945–952.

Fatigue in Aviation: Safety Risks, Preventive Strategies and Pharmacological Interventions

“…Moreover, severely fatigued pilots had higher rates of excessive daytime sleepiness, depression and obstructive sleep apnea than non-fatigued pilots ( O’Hagan et al, 2018 ). Levels of cardiovascular strain were found to be higher on day 4 than on day 1 of a work period, consistent with the hypothesis that fatigue and work periods increase cardiac strain among aircrew ( Goffeng et al, 2019a ). These long-term detrimental effects of circadian rhythm disruption and fatigue have also been observed in other occupational areas.…”

Detection of mental fatigue state using heart rate variability and eye metrics during simulated flight

“…Although a positive correlation between workload and mental fatigue level has been reported (Arsintescu et al, 2020), they may cause the opposite effect on operators; for example, fatigue generally causes decreased alertness, but workload may induce higher arousal and vigilance (Arsintescu et al, 2020; Kinney & O'Hare, 2020). Although most previous studies reported a decreased SDNN under mental fatigue, indicating enhanced mental stress (Cao et al, 2019; Castaldo et al, 2015; Goffeng et al, 2019), SDNN in this study was found to increase significantly. A possible interpretation is that participants' stress got relieved when they became increasingly familiar with the experimental settings, causing interference to the mental fatigue consequences.…”

“…Specifically, LF, LFnu, and LF/HF significantly increased, while HFnu significantly decreased. Similar results have also been reported in fatigued pilots who performed prolonged flight tasks or stayed awake for lengthy hours (Alaimo et al, 2020; Cao et al, 2019; Cheng et al, 2018; Goffeng et al, 2019; Mansikka et al, 2016). Although LF may reflect both sympathetic and parasympathetic activity, LFnu and LF/HF can specifically reflect sympathetic tone (Castaldo et al, 2015).…”

“…Compared with subjective scales and task performance evaluation which are suitable for postevent analysis, psychophysiological measures are more practical for online fatigue measuring, because it can function continuously and discover fatigue at an early stage (Caldwell et al, 2009). In the aviation domain, a variety of psychophysiological measures have been demonstrated to be sensitive to mental fatigue, including electroencephalogram (EEG), functional near‐infrared spectroscopy (fNIRS), electrocardiogram (ECG), and eye‐tracking (Cao et al, 2019; Di Stasi & Diaz‐Piedra, 2019; Gateau et al, 2018; Goffeng et al, 2019; Sauvet et al, 2014; Verdière et al, 2018; C.‐W. Wang et al, 2020; Wu et al, 2019).…”

“…In the aviation field, a prior work conducted by Cheng et al (2018) suggested that HRV indicators were capable of distinguishing pilots' normal functional states from the fatigue states induced by sleep deprivation, which indicated the potentiality of HRV in pilot fatigue detection. Besides, several studies suggested that HRV could reflect pilots' mental workload and stress level (Alaimo et al, 2020; Cao et al, 2019; Goffeng et al, 2019; Mansikka et al, 2016), both of which were known contributors to in‐flight mental fatigue (Dai et al, 2020; Caldwell et al, 2009). From the device aspect, the fast‐developing unobtrusive ECG sensors, such as wristbands, armbands, chest straps, and embedded sensors (Kranjec et al, 2014; Rodrigues et al, 2018; Villani et al, 2020; N. Wilson et al, 2020), could replace traditional recorder systems which use contact ECG electrodes, thus further enhancing HRV's feasibility in real‐life conditions.…”