Perioperative management of patients with chronic obstructive lung disease : establishment of risk assessment for development of aspiration pneumonia after surgery

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Incidence of postoperative respiratory complication is higher in patients with chronic obstructive lung disease (COPD) than non COPD patients. We hypothesized that impairment of airway protective reflexes in COPD patients may contribute to development of pulmonary aspiration.Study 1 : In order to assess possible interaction between presence of dyspneic sensation and airway protective reflexes, we assessed performance of cough reflex and types and intensity of dyspneic sensation immediately after breakpoint of a breath-hold. We found 1) presence of dyspneic sensation did not impair voluntarily and citric acid-induced coughing, 2) air hunger sensation increased and prolonged during reflexically-induced coughing, 3) either voluntary or reflexically-induced coughing did not increase dyspneic sensation without preceding breath holding. These results suggest little contribution of dyspneic sensation to impairment of airway protective function in COPD patients, and more importantly occurrence … More of pulmonary aspiration is not predicted by intensity of dyspnea in COPD patients.Study 2 : In order to assess swallowing function and mechanisms of its impairment, swallowing was induced by continuous infusion of distilled water into the pharynx in COPD patients. Unlike swallowing during resistive load in healthy subjects, number of swallows induced by the water infusion was not abnormally reduced. While swallows were predominantly induced during expiration and rarely induced during inspiration in healthy subjects, inspiratory or end-expiratory swallows were frequently observed in COPD patients. Considering incomplete swallows during inspiration or end expiration could aspirate materials in the pharynx into the trachea-bronchial trees, the swallowing pattern of COPD patients may increase chance of pulmonary' aspiration pneumonia.In conclusion, swallowing patterns of COPD patients should be preoperatively assessed by continuous infusion of distilled water into the pharynx despite intensity of dyspneic sensation. Less