Cardiopulmonary Consequences of Pyrogen-Induced Hyperpyrexia in Man*

The physiologic consequences of hyperpyrexia attracted considerable interest when artificially-induced fever was a popular therapeutic maneuver (1-10). Although induced hyperpyrexia has lapsed from therapeutic favor, the effects of body temperature elevation in response to infection, en-vironmental factors, or pyrogenic drugs remain a source of concern, especially in patients with cardiac or pulmonary dysfunction. Prior investigations have indicated that fever, whether induced by external heating or pyrogen injection, is accompanied by significant cardiac and peripheral hemodynamic alterations in both animals and man (1-4, 10, 11). However, data concerning respiratory gas exchange, pulmonary hemodynamics, and arterial blood gas composition in hyperpyrexia are rather fragmentary and incon-clusive (7-9, 12-17). The purpose of this study was to evaluate si-multaneously the changes in body temperature, pulmonary and systemic hemodynamics, respira-tory gas exchange, and arterial blood gas com-position that occur in normal subjects after the intravenous injection of a pyrogenic lipopolysac-charide extract of gram-negative bacilli. Since prior studies in man have not included cardiac catheterization and detailed measurement of re-spiratory function, it was felt that an investigation using the techniques now available would shed further light upon the cardiopulmonary conse-quences of the pyrogenic reaction in man. MATERIALS AND METHODS Ten male subj ects ranging from 33 to 74 years of age (mean 45.6) were studied. All were free of cardiac and pulmonary disease by clinical and routine laboratory criteria. All subjects were studied in the morning after