Ramazzini; Blog on work and health by Annet Lenderink

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Working night shifts may be bad for the heart

This study in Austria among 30 healthy physicians was performed to evaluate the effects of a 24 h (h) physicians on-call duty (OCD) (‘night shift’) on 24 h electrocardiogram (ECG), heart rate variability, blood pressure (BP), and various biochemical serum and urine ‘stress markers’ compared with a ‘regular’ day at work. Twenty-four hours ECG showed a higher rate of ventricular premature beats (VPB) during early morning hours.  During OCD, BP monitoring revealed a greater diastolic BP throughout 24 h as well as during night-time and a higher rate of systolic BP during sleep time. Tumour necrosis factor alpha concentrations increased significantly during night shift and urinary noradrenaline excretion was greater during OCD when compared with control day. The researchers conclude that there is an association of OCD with an increased risk profile for cardiovascular disease.

Arrhythmias and increased neuro-endocrine stress response during physicians’ night shifts: a randomized cross-over trial
Markus Rauchenzauner, Florian Ernst, Florian Hintringer, Hanno Ulmer, Christoph F. Ebenbichler, Marie-Therese Kasseroler and Michael Joannidis
European Heart Journal 2009 30(21):2606-2613; doi:10.1093/eurheartj/ehp268 online publish-ahead-of-print 14 July 2009

Aims: To evaluate the effects of a 24 h (h) physicians on-call duty (OCD) (‘night shift’) on 24 h electrocardiogram (ECG), heart rate variability, blood pressure (BP), and various biochemical serum and urine ‘stress markers’ compared with a ‘regular’ day at work.

Methods : The study was designed as a prospective randomized cross-over trial with each physician completing a 24 h (h) OCD and a 24 h control period including a regular 8 h non-OCD. Thirty healthy physicians with a median age of 33.5 years (range 29.0–45.0) were analysed. Twenty-four hours ECG and BP monitoring were performed and participants were instructed to fill out an event diary and perform a 24 h urine collection. Furthermore, blood was drawn before and after OCD and control day.

Results: Twenty-four hours ECG showed a higher rate of ventricular premature beats (VPB) during early morning hours (VPB 0–6 h, 0.5 vs. 0.0, P = 0.047) and increased low-frequency normalized units (29.3 vs. 25.5, P = 0.050) during night shift when compared with respective control night at home. During OCD, BP monitoring revealed a greater diastolic BP throughout 24 h (83.5 vs. 80.2 mmHg, P = 0.025) as well as during night-time (75.4 vs. 73.0, P = 0.028) associated with a higher rate of systolic BP more than 125 mmHg during sleep time. Tumour necrosis factor alpha concentrations increased significantly during night shift (0.76 vs. 0.05 pg/mL, P = 0.045). Urinary noradrenaline excretion was greater during OCD when compared with control day (46.0 vs. 36.0 µg/24 h, P = 0.007).

Conclusion: Our results highlight the association of OCD with an increased risk profile for cardiovascular disease. In addition to the acute effects observed, frequent night-calls over a longer period possibly elicit sustained alterations in cardiovascular homeostasis.

Filed under: cardio vascular, Occupational medicine, Psychosocial exposure, , ,

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