Changes in Heart Rate and Rhythm During a Crossover Study of Simulated Commercial Flight in Older and Vulnerable Participants.

Mark J Meyer,Irina Mordukhovich,Brent A Coull,John P Mccracken,Eileen Mcneely,Gregory A Wellenius,Murray A Mittleman

doi:10.3389/fphys.2019.01339

Abstract

Objectives: Elderly passengers and those with preexisting disease are flying with increasing frequency and in-flight cardiac emergencies are a more frequent occurrence. We conducted a study of the physiological effects of simulated cabin altitudes and resulting lower oxygen levels among such passengers.Methods: We monitored 41 participants in a hypobaric chamber for 2 days, one at an equivalent of 7,000 feet altitude (regulations limit pressurization to 8,000 feet) for a 4–5 h simulated flight and the other at ground level using generalized least squares models to account for repeated measures. We evaluated associations between simulated flight, heart rate (HR) and measures of heart rate variability(HRV) (root mean square of successive R-R interval differences [RMSSD], standard deviation of normal-to-normal intervals [SDNN], high-frequency power [HF], and low-frequency power [LF]).Results: Heart rate was 3.9% (95% CI: 2.1, 5.8) higher on simulated flight days compared with non-flight days. The RMSSD was 10.6% (95% CI: −21.3, 0.05) lower during simulated flight days, indicative of reduced HRV. The remaining HRV measures were also lower on simulated flight days, though associations were less precise.Conclusion: We report that typical simulated flight conditions elicit changes in cardiac autonomic control, suggesting sympathetic arousal or reductions in parasympathetic drive. Our findings, if confirmed, may suggest the need for guidelines to protect vulnerable passengers including prescreens, symptom evaluation after air travel, the use of oxygen concentrators, and education about healthy behaviors in flight.

Highlights

Air transportation is a commonplace means of travel, with over 2.75 billion passengers flying on commercial airlines annually (Peterson et al, 2013)
Our final sample was selected to reflect the aging population and included three main risk groups: (1) moderate cardiac disease patients, including coronary artery disease patients with a past history of severe blockage or infarction and congestive heart failure (CHF) patients classified as 1 and II according to New York Heart Association criteria [n = 13], (2) current tobacco smokers [n = 14], and (3) nonsmokers without reported cardiac disease, but including those with a stable chronic disease diagnosis, such as hypertension, asthma, diabetes, obesity, or mental illness [n = 14]
Average unadjusted changes in pre- versus post-simulated flight HR and HRV levels for the flight and control days are shown in Figure 1 overall and for each participant individually

Summary

Introduction

Air transportation is a commonplace means of travel, with over 2.75 billion passengers flying on commercial airlines annually (Peterson et al, 2013). While commercial airplanes fly at altitudes of around 34,000 feet, Federal Aviation Administration (FAA) regulations limit cabin pressurization to an equivalent of 8,000 feet, which is the typical pressurization implemented by most aircraft. Pressurization to this equivalent is selected to balance preventing acute altitude-related health symptoms among flyers with operational demands on the aircraft. Complications may be influenced by flight characteristics, activity during flight, lifestyle factors, and medical history, and include activation of the sympathetic nervous system, increased myocardial demand, paradoxical vasoconstriction, and alterations in cardiac autonomic control and hemodynamics that may in turn increase risk for flight-related cardiovascular events (Higgins et al, 2010; Wilkins et al, 2015)

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