[Endothelial dysfunction in cardiologists after 24 hours on call].

The objective was to determine if the stress caused by 24 hours on call in a cardiology emergency room alters endothelial function assessed by high-resolution ultrasonography in the brachial artery. Fifteen young physicians were studied in a crossover design: a) after a normal night of sleep at home, and b) after 24 hours on call without sleeping in an emergency room. Both studies were made at rest, 5 minutes after forearm occlusion and 3 minutes after administration of sublingual nitroglycerin. High-resolution ultrasonography and a 7.5-MHz linear array transducer were used to measure the brachial artery lumen. After 24 hours on call, physicians had significantly higher resting systolic and diastolic blood pressure. They also had a non-significant increase in heart rate and a lower brachial artery diameter. Brachial artery dilatation caused by hyperemia was only 3.35%, while it increased to 11.34% after normal sleep (p < 0.001). Only 2 physicians showed more than 4.4% dilatation, which was considered a normal response, while 13 had more than 4.4% after a normal night of sleep at home (p < 0.01). The response to nitroglycerin was similar under control conditions and after 24 hours of duty oncall.In conclusion, stress caused by 24 hours on call in a cardiology emergency room depresses or abolishes endothelial function.