HEMODYNAMIC-RESPONSE TO HYPERVENTILATION TEST IN HEALTHY-VOLUNTEERS

Hyperventilation is well known to affect the elec trocardiogram (EGG) in subjects without heart disease and produce spasm in patients with v ariant angina. The autonomic nervous system is thought to play a signi ficant role in these effects. However, the normal hemodynamic response to hyperventilation is not well defined. We subjected 369 healthy vol unteers (200 men, 169 women) to prolonged hyperventilation (30 respira tions for 5 min and 10 min recovery) under continuous ECG monitoring a nd to exercise testing. Heart rate (HR), systolic and diastolic blood pressures (SEP, DBP) and rate-pressure product were recorded. Hyperven tilation resulted in an immediate (within the first min), significant increase in HR by 27.4%, a further small increase at min 2 of hyperven tilation, and a subsequent small decrease in HR at mins 3-5. An immedi ate drop of HR by 20.1% was observed with discontinuation of hypervent ilation. Apart from a slightly higher HR increase in men, a similar pa ttern of HR changes was found in both genders. On multivariate analysi s, younger age, absence of smoking, and male gender were associated wi th a higher HR increase with hyperventilation (p < 0.0001, p < 0.0001, and p < 0.001, respectively. SEP and DBP increased with hyperventilat ion, with their highest value at min 5 of hyperventilation and a subse quent drop to baseline levels. Age and gender did not affect the degre e and pattern of BP changes. Absence of smoking and the presence of hy pertension were associated with a higher SEP with hyperventilation (p < 0.003 and p < 0.007). The rate-pressure product increased by 43.6% w ith hyperventilation, a change that was only 19.1% of the respective r ate pressure product observed with exercise. Hyperventilation results in significant HR and BP increases, changes that are influenced by age , gender, smoking, and hypertension. Ourstudy could serve as a standar d for comparison of the hyperventilation effects in different disease states.