Rapid regular respiration in unconscious patients.

Respiratory frequency has been studied by strain gauge and impedance pneumography in a group of unconscious patients suffering from a variety of medical conditions, and has been compared with breathing in control subjects during wakefulness and sleep. Seventeen of 25 comatose patients had breathing patterns amenable to computerized statistical analysis of respiratory rate which demonstrated abnormalities in all patients studied. Unconscious patients breathed more rapidly and regularly than controls. Rapidity of respiration was not consistently associated with any specific central nervous system lesion, and was usually accompanied by coexistent pulmonary disease. Increasing regularity of respiration correlated well with deepening of coma and accurately reflected ultimate outcome even when other clinical signs were unchanging.