In man, hypocapnia induced by hyperventilation causes a drop in arterial pressure. The calculated peripheral resistance is decreased, indicating a net vasodilatation. The forearm blood flow is markedly increased, and the vascular resistance of the forearm is much reduced. Persons with impaired function of the sympathetic nervous system continue to show these effects. The increase in forearm flow is not prevented by brachial block. These results suggest that hypocapnia acts directly on blood vessels to produce a net over-all vasodilatation and fall in blood pressure, and that this effect is not mediated through the nervous system, as usually supposed.

Medical record information has become less reliable than ever before despite the electronic information revolution in medical care and the authority medical records have been accorded in our society. Long flawed by errors introduced by medical personnel, patients, and machines, medical records have had a further decline in credibility as a result of the loss of confidentiality and the imposition of well-meaning but unrealistic cost-control regulations on medical practice. Medical records are being distorted and fashioned to keep clinically important but sensitive personal information about patients from public view. To comply with standards of care and a reimbursement system blind to biologic diversity, medical records are being forced to address only the technical side of care. Until these deficiencies are corrected, our increasing dependence on medical records should be balanced by increasing skepticism about the value of the information they contain.

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In normal subjects hyperventilation causes a drop in arterial blood pressure, apparently because of the direct effect of hypocapnia on the peripheral vessels. In persons with disease of the autonomic nervous system, the drop in blood pressure is much greater because it is not effectively opposed by reflex vasoconstriction. Consequently, hyperventilation caused by anxiety may greatly intensify postural hypotension in such patients and contribute significantly to their disability. A pertinent case is reported.

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