Liberation From Mechanical Ventilation

Multiple complications associated with mechanical ventilation mandate that clinicians expeditiously define and reverse the pathophysiologic processes that precipitate respiratory failure and then, detect the earliest point that a patient can breathe without the ventilator. Over the past decade, numerous laboratory and clinical studies have been reported that may inform transformation of the “art of weaning” to the science of liberation. We review these studies and use them to formulate a systematic approach to assure early, safe, and successful liberation of patients from mechanical ventilation. (CHEST 1998; 114:886–901) Abbreviations: CO2=carbon dioxide; CPAP=continuous positive airway pressure; CROP=compliance, rate, oxygenation, pressure; Crs=respiratory system compliance; MVV=maximum voluntary ventilation; NIPPV=noninvasive positive-pressure ventilation; P0.1 = airway occlusion pressure; PEEP=positive end-expiratory pressure; pHi=intramucosal pHi; PImax=maximum inspiratory pressure; PSV=pressure-support ventilation; RF=respiratory failure; ROC=receiver operating characteristic; RVR=rate:volume ratio (respiratory rate:tidal volume ratio); SIMV=synchronized intermittent mandatory ventilation; VA=alveolar ventilation; V ˙ co2=carbon dioxide output; VD=dead space ventilation; V ˙ E=minute volume Multiple complications associated with mechanical ventilation mandate that clinicians expeditiously define and reverse the pathophysiologic processes that precipitate respiratory failure and then, detect the earliest point that a patient can breathe without the ventilator. Over the past decade, numerous laboratory and clinical studies have been reported that may inform transformation of the “art of weaning” to the science of liberation. We review these studies and use them to formulate a systematic approach to assure early, safe, and successful liberation of patients from mechanical ventilation. (CHEST 1998; 114:886–901) Abbreviations: CO2=carbon dioxide; CPAP=continuous positive airway pressure; CROP=compliance, rate, oxygenation, pressure; Crs=respiratory system compliance; MVV=maximum voluntary ventilation; NIPPV=noninvasive positive-pressure ventilation; P0.1 = airway occlusion pressure; PEEP=positive end-expiratory pressure; pHi=intramucosal pHi; PImax=maximum inspiratory pressure; PSV=pressure-support ventilation; RF=respiratory failure; ROC=receiver operating characteristic; RVR=rate:volume ratio (respiratory rate:tidal volume ratio); SIMV=synchronized intermittent mandatory ventilation; VA=alveolar ventilation; V ˙ co2=carbon dioxide output; VD=dead space ventilation; V ˙ E=minute volume Weaning From Mechanical Ventilation: What Have We Learned and What Do We Still Need to Know?CHESTVol. 114Issue 3PreviewWeaning from mechanical ventilation (MV) can be defined as the process of abruptly or gradually withdrawing ventilatory support from patients whose underlying cause of respiratory failure has either improved or been resolved. While MV is lifesaving, it is associated with a number of potentially serious complications.1,2 Furthermore, MV is expensive and uncomfortable for the patient. Ideally, MV should be discontinued at the earliest possible opportunity. The problem the clinician faces is how to determine when a patient is ready to resume ventilation on his or her own.