Ventilatory Response during Menopausal Hot Flashes

Our study was conducted to define the characteristics of the ventilatory response associated with menopausal hot flashes. Two procedures were used. In the first procedure, respiratory volume was assessed in 2-min epochs before, during, and after hot flashes in eight postmenopausal women. The mean percentage changes for abdominal amplitude showed significant differences between the before and flash epochs and the before and post epochs. In the second procedure, direct metabolic measurements of ventilation were taken every 30 s during a 50-min period in nine postmenopausal women. Respiratory measurements occurring during a 4-min period beginning with the onset of a hot flash were isolated from the 50-min recording and compared to a stable baseline period. Tidal volume, oxygen consumption, and carbon dioxide production were all significantly increased during hot flashes compared to baseline. Minute ventilation significantly increased at the beginning of the hot flash, and breathing rate significantly declined as the hot flash progressed, compared to baseline. These data suggest that alterations in respiration consistently occur in conjunction with menopausal hot flashes and that menopausal symptomatology may involve several diverse biological systems that may be responsive to different treatment approaches.