Studies for improvement of perioperative management for patients with chronic respiratory failure.

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To obtain information for improvement of perioperative management of patients with chronic respiratory failure, this study focused on problems of respiratory load compensation, defensive airway reflexes, and dyspnea. The study on respiratory and behavioral compensation during chronic severe loading in an awake rat mode suggests that severe chronic ventilatory loading may induce adaptive response that compensate rapidly the disturbed acid-base balance with slow and gradual increases in ventilatory activity while matching the increase in motor activity/metabolic rate. Concerning the defensive airway reflexes, the coordination of respiration and swallowing reflex in human was investigated. This study showed that an increase in lung volume prolongs the latency of swallowing reflex elicited by bolus injection of water into the pharynx and decreases the number of swallows during continuous infusion of water. In addition, changes in lung volume modulated the timing of swallowing in reference … More to the respiratory cycle. These observations suggest that vagally-mediated reflexes may play an important role in the control of swallowing rate as well as the timing of swallowing in reference to the respiratory cycle. The most remarkable result obtained from the studies on dyspnea is that inhaled furosemide greatly improves the sensation of experimentally-induced dyspnea in humans. The mechanisms of this effect of inhaled furosemide were investigated in anesthetized rats. The results showed that inhaled furosemide sensitizes slowly-adapting receptors and desensitizes rapidly-adapting receptors. Thus, activation of pulmonary stretch receptors and inhibition of vagal irritant receptors seems to be the most plausible explanation for the improvement of dyspneic sensation following inhalation of furosemide in humans. Inhaled furosemide also suppressed the behavioral response to airway occlusion in anesthetized animals without affecting the response to somatic noxious stimulus. This animal model may be applicable to the study of dyspnea concerning its mechanism and treatment. Less