The validity of linear and non-linear heart rate metrics as workload indicators of emergency physicians

Abstract

BackgroundIt has been shown that linear and non-linear heart rate variability (HRV) metrics are suitable to assess workload of anesthetists administering anesthesia. In pre-hospital emergency care, these parameters have not yet been evaluated. We hypothesized that heart rate (HR) and HRV metrics discriminate between differing workload levels of an emergency physician.MethodsElectrocardiograms were obtained from 13 emergency physicians. Mean HR, ten linear and seven non-linear HRV metrics were analyzed. For each sortie, four different levels of workload were defined. Mixed-effects models and the area under the receiver operating characteristics curve (AUC) were used to test and quantify the HR and HRV metrics’ ability to discriminate between levels of workload. This was conducted for mean HR and each HRV metric as well as for groups of metrics (time domain vs. frequency domain vs. non-linear metrics).ResultsThe non-linear HRV metric Permutation entropy (PeEn) discriminated best between the time before the alarm and primary patient care (AUC = 0.998, 1st rank of 18 HRV metrics). In contrast, AUC of the mean HR was low (0.558, 17th rank). In the multivariable approach, the non-linear HRV metrics provided a higher AUC (0.998) compared to the frequency domain (0.677) and to the time domain metrics (0.680).ConclusionNon-linear heart rate metrics and, specifically, PeEn provided good validity for the assessment of different levels of a physician’s workload in the setting of pre-hospital emergency care. In contradiction to earlier findings, the physicians’ mean HR was not a valid marker of workload.

The impact of the patient’s initial NACA score on subjective and physiological indicators of workload during pre-hospital emergency care

“…Parts of the results, specifically the results regarding the validity of linear and non-linear HRV metrics, have been published earlier. [ 15 ]…”

“…[ 9 ] In addition to heart rate itself (mean HR),[ 9 – 11 ] heart rate variability (HRV) metrics have been shown to quantify workload in experimental settings and under real-life circumstances. [ 9 , 12 – 15 ] Among these, the non-linear HRV metric Permutation Entropy (PeEn) has been found to be a sensible correlate of workload in anesthetists providing general anesthesia. [ 9 ] Our recent work indicated that non-linear HRV metrics can also distinguish workload levels during pre-hospital emergency care.…”

“…[ 9 ] Our recent work indicated that non-linear HRV metrics can also distinguish workload levels during pre-hospital emergency care. [ 15 ] However, though excessive workload may impair patient safety,[ 16 – 18 ] data on workload during pre-hospital care including cardiopulmonary resuscitation (CPR) are still scarce.…”

A comparison of linear and nonlinear ECG-based methods to assess pilot workload in a live-flight tactical setting

“…A number of studies have compared linear and nonlinear HRV metrics (Francesco et al, 2012;Schneider et al, 2017;H. Young & Benton, 2015).…”

“…The majority, however, have been related to HRV analysis in clinical diagnosis (Francesco et al, 2012). A smaller number of studies have assessed the relative utility of these methods as compared to time and frequency domain methods in mental MWL research (Heine et al, 2017;Schneider et al, 2017;H. Young & Benton, 2015).…”