Respiratory system loop gain in normal men and women measured with proportional-assist ventilation

• Published in: Journal of applied physiology (1985) Vol. 94; no. 1; pp. 205 - 212
• Main Authors: Wellman, Andrew, Malhotra, Atul, Fogel, Robert B, Edwards, Jill K, Schory, Karen, White, David P
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.01.2003; American Physiological Society
• Subjects: Adult; Anatomy & physiology; Biological and medical sciences; Cardiorespiratory control. Arterial mecano- and chemoreceptor; Feedback; Female; Fundamental and applied biological sciences. Psychology; Gender; Humans; Male; Middle Aged; Periodicity; Positive-Pressure Respiration; Reference Values; Respiratory Mechanics; Respiratory Physiological Phenomena; Respiratory system; Sex Characteristics; Tidal Volume; Vertebrates: respiratory system; Human; Nervous system diseases; Stability; gender; Sex; Sleep disorder; Respiratory system; Apnea; Sleep; ventilatory stability; Pulmonary ventilation; Respiration; Respiratory control; sleep apnea; control of breathing
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00585.2002

1  Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, and 2  Harvard Medical School, Boston, Massachusetts 02115 We hypothesized that increased chemical control instability (CCI) in men could partially explain the male predominance in obstructive sleep apnea (OSA). CCI was assessed by sequentially increasing respiratory control system loop gain (LG) with proportional-assist ventilation (PAV) in 10 men (age 24-48 yr) and 9 women (age 22-36 yr) until periodic breathing or awakening occurred. Women were studied in both the follicular and luteal phases of the menstrual cycle. The amount by which PAV amplified LG was quantified from the tidal volume amplification factor [(V T AF) assisted tidal volume/unassisted tidal volume]. LG was calculated as the inverse of the V T AF occurring at the assist level immediately preceding the emergence of periodic breathing (when LG × V T AF = 1). Only 1 of 10 men and 2 of 9 women developed periodic breathing with PAV. The rest were resistant to periodic breathing despite moderately high levels of PAV amplification. We conclude that LG is low in the majority of normal men and women and that higher volume amplification factors are needed to determine whether gender differences exist in this low range. ventilatory stability; gender; sleep apnea; control of breathing