Respiration Physiology (1987) 68, 331-344 Elsevier 331 RSP 01286 Evidence for individuality of breathing patterns in resting healthy man S.A. Shea, J. Walter, K. Murphy and A. Guz Department of Medicine. Charing Cross and Westminster Medical School, London, U.K. (Accepted for publication 3 February 1987) Abstract. This study attempts to answer the question of whether there is a characteristic individuality of breathing pattern in conscious man. Measurements of breathing pattern, electroencephalograms and electrooculograms were made on 41 healthy individuals under standardised conditions of relaxed wake- fulness, with a minimum of visual, auditory, and tactile input. Noninvasive measurement techniques were utilised and the subjects did not know that their breathing was being monitored. Measurement periods of only 5 min were used in order to avoid sleep. To estimate reproducibility, subjects were studied four times over two days. A variety of statistical tests on respiratory and cardiovascular variables indicate that the differences between individuals are highly significantly greater than the differences within an individual on repeated measurements under these standardised conditions. There was a high degree of reproducibility of breathing pattern within a subject; respiratory frequency was the most reproducible variable. Control of breathing; Pattern of breathing; Rest; Ventilation Measurements of resting breathing patterns are frequently reported but there has been no previous attempt to standardise the definition of rest or the methodology required for such measurements. Any attempt to record such steady-state baseline resting breathing patterns requires a relaxed subject, with a minimum of sensory input, motor output, and cognitive activity whilst avoiding sleep or other fluctuations in the level of alertness. Resting breathing patterns are also difficult to interpret because they are not necessarily the consequence of a metabolic signal alone - there is a complex interaction between the metabolic and the behavioral control of breathing such that at times of low metabolic demand the behavioral system has potentially its greatest effect (Morgan and Cameron, 1984). This behavioral ‘noise’ may be amplified if the subjects know, and think about, the fact that their breathing is being measured. In addition, a mouthpiece has been shown to significantly affect the breathing pattern and level of ventilation (Gilbert et al., 1972). Correspondence address: S. A. Shea, Department of Medicine, Charing Cross and Westminster Medical School. Fulham Palace Road, London W6 8RF, U.K. 0034-5687/87/$03.50 0 1987 Elsevier Science Publishers B.V. (Biomedical Division)