title: Maximal tachycardia and high cardiac strain during night shifts of emergency physicians.
abstract: OBJECTIVE
  To compare tachycardia and cardiac strain between 24-hour shifts (24hS) and 14-hour night shifts (14hS) in emergency physicians (EPs), and to investigate key factors influencing tachycardia and cardiac strain.
  
  
  METHODS
  We monitored heart rate (HR) with Holter-ECG in a shift-randomized trial comparing a 24hS, a 14hS, and a control day, within a potential for 19 EPs. We also measured 24-h HR the third day (D3) after both shifts. We measured perceived stress by visual analog scale and the number of life-and-death emergencies.
  
  
  RESULTS
  The 17 EPs completing the whole protocol reached maximal HR (180.9 ± 6.9 bpm) during both shifts. Minutes of tachycardia >100 bpm were higher in 24hS (208.3 ± 63.8) than in any other days (14hS: 142.3 ± 36.9; D3/14hS: 64.8 ± 31.4; D3/24hS: 57.6 ± 19.1; control day: 39.2 ± 11.6 min, p < .05). Shifts induced a cardiac strain twice higher than in days not involving patients contact. Each life-and-death emergency enhanced 26 min of tachycardia ≥100 bpm (p < .001), 7 min ≥ 110 bpm (p < .001), 2 min ≥ 120 bpm (p < .001) and 19 min of cardiac strain ≥30% (p = .014). Stress was associated with greater duration of tachycardia ≥100, 110 and 120 bpm, and of cardiac strain ≥30% (p < .001).
  
  
  CONCLUSIONS
  We demonstrated several incidences of maximal HR during shifts combined with a high cardiac strain. Duration of tachycardia were the highest in 24hS and lasted several hours. Such values are comparable to those of workers exposed to high physical demanding tasks or heat. Therefore, we suggest that EPs limit their exposure to 24hS. We, furthermore, demonstrated benefits of HR monitoring for identifying stressful events. ClinicalTrials.gov identifier: NCT01874704.
authors.affiliation: University Hospital of Clermont-Ferrand (CHU), Occupational and Preventive Medicine, F-63000, Clermont-Ferrand, France. frederic.dutheil@uca.fr.|University Hospital of Clermont-Ferrand (CHU), Emergency department, F-63000, Clermont-Ferrand, France. frederic.dutheil@uca.fr.|Université Clermont Auvergne, CNRS, LaPSCo, Physiological and Psychosocial Stress, F-63000, Clermont-Ferrand, France. frederic.dutheil@uca.fr.|Australian Catholic University, Faculty of Health, School of Exercise Science, Melbourne, VIC 3065, Australia. frederic.dutheil@uca.fr.|WittyFit, F-75000, Paris, France. frederic.dutheil@uca.fr.
authors.forename: Frédéric
authors.identifier: http://orcid.org/0000-0002-1468-6029
authors.initials: F
authors.lastname: Dutheil
authors.affiliation: University Hospital of Toulouse, Anesthesiology and Intensive Care Unit, F-31000, Toulouse, France.
authors.forename: Fouad
authors.initials: F
authors.lastname: Marhar
authors.affiliation: University Hospital of Clermont-Ferrand (CHU), Occupational and Preventive Medicine, F-63000, Clermont-Ferrand, France.
authors.forename: Gil
authors.initials: G
authors.lastname: Boudet
authors.affiliation: University Hospital of Clermont-Ferrand (CHU), Emergency department, F-63000, Clermont-Ferrand, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Perrier
authors.affiliation: Australian Catholic University, Faculty of Health, School of Exercise Science, Melbourne, VIC 3065, Australia.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Naughton
authors.affiliation: University Hospital of Clermont-Ferrand (CHU), Occupational and Preventive Medicine, F-63000, Clermont-Ferrand, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Chamoux
authors.affiliation: Université Clermont Auvergne, CNRS, LaPSCo, Physiological and Psychosocial Stress, F-63000, Clermont-Ferrand, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Huguet
authors.affiliation: Université Grenoble Alpes, CNRS, Laboratory of Cognition and NeuroPsyhology (LPNC), F-38000, Grenoble, France.|Institut Universitaire de France, F-75000, Paris, France.
authors.forename: Martial
authors.initials: M
authors.lastname: Mermillod
authors.affiliation: Saudi Electronic University, College of Sciences and Theoretical Studies, Riyadh, 13316, Saudi Arabia.
authors.forename: Foued
authors.initials: F
authors.lastname: Saâdaoui
authors.affiliation: University Hospital of Clermont-Ferrand (CHU), Emergency department, F-63000, Clermont-Ferrand, France.
authors.forename: Farès
authors.initials: F
authors.lastname: Moustafa
authors.affiliation: University Hospital of Clermont-Ferrand (CHU), Emergency department, F-63000, Clermont-Ferrand, France.
authors.forename: Jeannot
authors.initials: J
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D015992:Body Mass Index; D004635:Emergency Medicine; D005260:Female; D005602:France; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D015999:Multivariate Analysis; D016273:Occupational Exposure / Q000009:adverse effects*; D010820:Physicians / Q000523:psychology*; D012307:Risk Factors; D000073577:Shift Work Schedule / Q000009:adverse effects*; D020178:Sleep Disorders, Circadian Rhythm; D013312:Stress, Physiological; D013315:Stress, Psychological / Q000150:complications*; D011795:Surveys and Questionnaires; D013610:Tachycardia / Q000523:psychology*; D064232:Visual Analog Scale; D014940:Work Schedule Tolerance / Q000502:physiology
keywords: Death; Heart rate; Occupation; Relative cardiac cost; Sleep; Strain; Stress; Work