Abstract
Objective: To determine the impact of sleep deprivation due to night shift/duty in ITU nurses and doctors on the QT interval and the index of cardio-electrophysiological balance (ICEB), predictors of arrhythmias. Design: Observational trial.
Setting: University Hospital ITU. Materials and methods: Nurses/doctors on night shift/duty.
Standard 12-lead ECG before and after the shift was recorded. Heart rate, QRS, QT from automated analysis, corrected QTc using Hodges formula and ICEB = QT/QRS were calculated.
A questionnaire on the health status and sleep behaviour was filled in. Results: Total 59 participants, 18 men (30.5%), 41 women (69.5%), 45 nurses (76.3%, 35 women, 10 men), 13 doctors (22 %, 7 men, 6 women), 1 hospital attendant (1.7%), age 35.3 +/- 5.6 years, all fit for night shift/duty.
Mean usual sleep duration was 6.7 +/- 0.6 hours, mean sleep duration before the shift was 6.3 +/- 1.9 hours, nurses did not sleep during the shift, doctors slept for 4.3 +/- 1.0 hour with 0- 3 interruptions per night. Heart rate before the shift was 68 +/- 10, after the shift 64 +/- 10, QRS 90.9 +/- 12.3 ms and 92.6 +/- 12,8 ms respectively, QT 387.6 +/- 28 ms and 402.9 +/- 31.3 ms respectively, corrected QT interval (Hodges) 400.2 +/- 19.3 ms and 409.2 +/- 21.5 ms respectively, ICEB increased from 4.32 +/- 0.57 to 4.43 +/- 0.66.
Conclusion: One night of insufficient sleep due to a night shift on the ITU prolongs the QT and QTc intervals, and increases ICEB. These changes might contribute to the negative impact of shift work on the health status of healthcare workers in the short and long-term perspective.