Effects of negative pressure assisted ventilation on dyspnoeic sensation and breathing pattern

Although negative pressure assisted ventilation with an assist-control made may have a potential therapeutic role in the treatment of severe dyspnoea, the effects of negative pressure assisted ventilation with the assist-cont rol made on dyspnoea and breathing patterns have not been examined. We examined the effects of negative pressure assisted ventilation with the assist-control mode on dyspnoea and breathing patterns produced by a combin ation of resistive loading and hypercapnia in nine healthy subjects breathi ng spontaneously, Subjects were asked to rate their sensation of respirator y discomfort using a visual analogue scale. Negative pressure assisted ventilation caused a significant reduction in se nsation of respiratory discomfort from a visual analogue scale score of 74 (55-91) (median (range)) before negative pressure assisted ventilation to 3 4 (15-53) during negative pressure assisted ventilation (p<0.01). During ne gative pressure? assisted ventilation, there were significant changes in br eathing patterns characterized by an increase in tidal volume,and a decreas e in respiratory frequency, while neither minute ventilation nor end-tidal carbon dioxide tension changed. Our results indicate that negative pressure assisted ventilation with the a ssist-control mode is effective in relief of dyspnoea and that negative pre ssure assisted ventilation influences the control of breathing to minimize respiratory discomfort.