Another cardiovascular risk factor - 24 hour hospital shifts! A paper published in the November 2009 European Heart Journal (http://eurheartj.oxfordjournals.org/cgi/content/abstract/30/21/2606) examined the effects of a long workday on several markers of cardiovascular stress.

30 healthy physicians (aged 29-45 years) were monitored by 24 ECG, urine collection, blood tests and sleep diaries. This gave a snapshot of the consequences of their work on their cardiovascular, neuroendocrine and inflammatory systems. The novel aspect of the study was its prospective, randomised crossover design. This meant that each subject completed not only a 24 hour ‘on-call’ shift, but also a 24 hour ‘not on-call’ day featuring only 8 hours of work followed by sleeping at home. Doctors were recruited across three specialities - neurology, internal medicine and ENT at Innsbruck University Hospital, Austria.

Being on-call was associated with higher blood levels of tumour necrosis factor, as well as higher urine levels of adrenaline and noradrenaline. Blood pressure values were also greater whilst working. There were more VPB’s noted during ECG monitoring. These effects are likely due to changes in the balance between sympathetic and parasympathetic systems induced by being awake for longer.

Some of this is not new. It’s already known that irregular working hours are associated with an increased incidence of cardiovascular disease including MI, even when corrected for existing risk factors.

What can we conclude? It seems that pulling 24 hour shifts disturbs several body systems and alters your risk factor profile towards cardiovascular disease. Working at night is a necessary evil as patients don’t stop needing treatment at 5pm. But perhaps shorter shifts with longer rest breaks might ultimately give us healthier doctors.