Effects of Three-Hour Wearing Personal Protective Equipment on Heart Rate Variability in Healthcare Workers for the Treatment of COVID-19 Patients

Figures & data

Table 1 Healthcare Workers’ Characteristics and Time-Domain HRV Indices Before and After the Shift

	Before the Shift (n = 65)	After the Shift (n = 65)	p
Sinus rhythm, n(%)	65 (100)	65 (100)	>0.05
Body weight, kg	67.4 ± 7.3	67.1 ± 7.1	0.005
Pulse rate, bpm	84.1 ± 13.1	87.6 ± 17.1	0.032
Body temperature, ^oC	36.4 ± 0.1	36.4 ± 0.2	>0.05
SBP, mmHg	113.6 ± 9.4	114.2 ± 8.6	>0.05
DBP, mmHg	74.9 ± 8.3	75.6 ± 8.7	>0.05
SpO2, %	97.7 ± 0.9	97.4 ± 0.8	0.035
Heart rate, bpm	75.9 ± 11.0	78.6 ± 13.6	0.048
QT interval, ms	375.6 ± 26.2	369.6 ± 27.2	0.012
SDNN, ms	28.1 (20.6–39.1)	23.4 (17.1–32.9)	0.031
Mean NN	19.2 (17.5–21.2)	18.1 (16.1–20.4)	0.008
rMSSD, ms	19.2 (17.6–21.2)	17.9 (16.0–20.9)	0.009

Abbreviations: bpm, beats per minute; SBP, systolic blood pressure; DBP, diastolic blood pressure; SpO2, saturation pulse oxygen; SDNN, standard deviation of all normal to normal intervals; NN, normal to normal RR; rMSSD, root mean square successive difference.

Table 2 Association of Heart Rate Variability Indices and Working Time

	Day Shift (6–21h) (n = 52)	Night Shift (21h-6h) (n = 13)	p
SDNN after the shift, ms	26.6 (19.8–37.3)	17.1 (13.7–18.9)	0.006
Mean NN after the shift	18.9 (16.1–21.6)	16.8 (16.2–17.9)	0.027
rMSSD after the shift, ms	18.5 (16.0–21.5)	16.9 (16.3–17.8)	0.03

Table 3 Association of Heart Rate Variability Indices and Working Intensity

	Severe Patient Dept. (n = 19)	Moderate Patient Dept. (n = 21)	Mild Patient Dept. (n = 25)	p
SDNN after the shift, ms	18.3 (14.0–21.2)	30.5 (22.4–38.9)	31.6 (23.7–39.5)	0.014
Mean NN after the shift	16.4 (14.6–19.5)	18.2 (16.9–19.6)	18.8 (16.8–23.1)	0.031
rMSSD after the shift, ms	16.3 (14.7–19.5)	18.3 (16.9–20.5)	18.5 (17.2–23.0)	0.012

Abbreviations: SDNN, standard deviation of all normal to normal intervals; NN, normal to normal RR; rMSSD, root mean square successive difference.

Table 4 Correlation Between Heart Rate Variability Indices and Healthcare Workers’ Characteristics After the Shift

	Log SDNN		Log Mean NN		Log rMSSD
	r	p	r	p	r	p
Body weight, kg	0.01	0.91	−0.13	0.289	−0.1	0.429
Pulse rate, bpm	−0.31	0.01	−0.67	<0.001	−0.65	<0.001
Body temperature, ^oC	0.01	0.892	0.008	0.952	0.03	0.789
SBP, mmHg	−0.05	0.659	−0.05	0.69	−0.05	0.662
DBP, mmHg	−0.208	0.099	−0.43	<0.001	−0.39	<0.001
SpO2, %	0.14	0.048	0.31	0.013	0.25	0.042
Heart rate, bpm	−0.42	0.001	−0.82	<0.001	−0.74	<0.001
QT interval, ms	0.39	0.001	0.77	<0.001	0.73	<0.001
Temperature inside PPE, ^oC	−0.41	0.001	−0.405	0.001	−0.29	0.016

Abbreviations: bpm, beats per minute; SBP, systolic blood pressure; DBP, diastolic blood pressure.

Table 5 Multivariate Regression Analysis of Heart Rate Variability Indices and Healthcare Workers’ Characteristics After the Shift

	Log SDNN		Log Mean NN		Log rMSSD
	Beta	p	Beta	p	Beta	p
Body weight, kg	0.015	0.9	−0.034	0.64	0.018	0.84
Body temperature, ^oC	0.028	0.82	−0.002	0.98	0.04	0.67
SBP, mmHg	−0.026	0.88	0.029	0.78	0.042	0.75
DBP, mmHg	−0.054	0.77	−0.129	0.27	−0.193	0.16
SpO2, %	−0.005	0.97	0.015	0.84	−0.022	0.81
Heart rate, bpm	−0.034	0.89	−0.41	0.009	−0.282	0.12
QT interval, ms	0.287	0.22	0.32	0.026	0.41	0.02
Temperature inside PPE, ^oC	−0.34	0.01	−0.18	0.021	−0.105	0.26

Abbreviations: bpm, beats per minute; SBP, systolic blood pressure; DBP, diastolic blood pressure.