변경할 수 있는 유순도 모델에서 호흡역학에 대한 상기도 폐쇄의 효과

Abstract

Introduction : Upper airway obstruction is caused by intrinsic or extrinsic neck mass, and vocal cord paralysis. A recognized hazard of prolonged endotracheal intubation is progressive airway occlusion resulting from deposition of secretions. If the obstruction persist, lead to life threatening condition. But early diagnosis of partial airway obstruction is very difficult due to patients are asymptomatic and can?t find abnormal radiologic lesion.

Methods : In the test lung model, lung compliances were set to normal (25 ml/cmH2O; control, C25 group) and to levels seen in chronic obstructive pulmonary disease (40 ml/cmH2O; C40 group), acute respiratory distress syndrome (20 ml/cmH2O; C20 group and 25 ml/cmH2O; C25 group). Set the tidal volume 600 ml, respiratory rate 10 bpm, inspiratory pause 1sec and limit of peak inspiratory pressure was 70 cmH2O. Ventilator (Dr?ger Fabius GS, medical AG & Co. Germany) by using a test lung and a series of endotracheal tube (ETT)s ranging in size from 7.5 to 2.5 mm inner diameter of connector to simulate progressive occlusion. Results : Progressive ETT occlusion induced increasing peak inspiratory pressure. C40 group was spontaneously increase inspiratory pause pressure when repeated ventilation. Auto-PEEP presented under the condition that high compliance and occlusion. Dynamic compliance was decreased at ID 5.5 mm in all groups. Respiratory resistance was in inverse proportion to inner diameter of connector.

Conclusion : Progressive ETT occlusion did not reduce delivered tidal volumes until occlusion was nearly complete (ID 2.5 mm). But dynamic compliance and respiratory resistance were significant changes at ID 5.5 mm that means decrease as 46.22 % of normal cross sectional area.