Lim T K
Department of Medicine, National University Hospital, Singapore.
Singapore Med J. 1990 Jun;31(3):233-7.
Patients with chronic obstructive pulmonary disease [COPD] breath at large lung volumes because of dynamic hyperinflation. Their end-tidal lung volumes will then be much above the equilibrium position of the respiratory system and the elastic recoil pressure would be above zero at end-tidal exhalation. This auto or intrinsic positive end-expiratory pressure [auto-PEEP] contributes to the elastic work of inspiration and the sensation of dyspnoea. The purpose of this study was to offset the auto-PEEP in patients with exacerbated chronic airflow obstruction by applying continuous positive airway pressure via the nose [nasal-CPAP]. Nine out of 14 patients experienced alleviation of dyspnoea while on nasal-CPAP [4 to 8 cmH2O]. These 9 patients had significantly more severe hyperinflation than the 5 patients who did not respond positively to nasal-CPAP. While there is a complex relationship between intrinsic and extrinsically applied PEEP in patients with COPD, the result of this study is consistent with the notion that CPAP may alleviate dyspnoea by reducing auto-PEEP, improving lung mechanics and unloading the inspiratory muscles. Nasal-CPAP may have a potential therapeutic role in exacerbations of COPD.
慢性阻塞性肺疾病（COPD）患者由于动态肺过度充气而在大肺容积下呼吸。其呼气末肺容积将远高于呼吸系统的平衡位置，呼气末呼气时弹性回缩压力将高于零。这种自动或内源性呼气末正压（auto-PEEP）会增加吸气的弹性功和呼吸困难的感觉。本研究的目的是通过经鼻应用持续气道正压通气（鼻CPAP）来抵消慢性气流阻塞加重患者的auto-PEEP。14例患者中有9例在使用鼻CPAP（4至8 cmH₂O）时呼吸困难得到缓解。这9例患者的肺过度充气比5例对鼻CPAP无阳性反应的患者严重得多。虽然COPD患者内源性和外源性应用PEEP之间存在复杂关系，但本研究结果与以下观点一致，即CPAP可通过降低auto-PEEP、改善肺力学和减轻吸气肌负荷来缓解呼吸困难。鼻CPAP在COPD加重期可能具有潜在的治疗作用。
