Haemodynamic and hormonal response to a stream of cooled air.

Many patients with angina note that their symptoms deteriorate in cold weather, although the precise physiological mechanism that explains this remains unclear. Exposure of the face to cool winds may be a contributory factor. The cardiovascular and hormonal response to a localised stream of room (22 degrees C) and cold (4 degrees C) air during submaximal treadmill exercise was therefore studied in nine normal subjects. Cardiac output and respiratory gases were measured with a mass spectrometer, using the indirect Fick principle. Blood samples were taken for plasma noradrenaline. A localised stream of air at 5 m.s-1 produced significant cardiovascular effects at rest, some of which persisted during exercise. In response to cold air, stroke volume, cardiac output, blood pressure and oxygen uptake increased (all P < 0.05). There was a trend towards a reduction in heart rate at rest and increase in plasma noradrenaline. Room air caused a reduction in blood pressure (P = 0.01) but stroke volumes and oxygen uptake were unchanged. The results of this study demonstrate significant cardiovascular effects of a cooled air facial stimulus at rest and during exercise. They may, in part, explain the effects of cold winds on patients with angina.