Physiological comparison of three spontaneous breathing trials in difficult-to-wean patients
- 1.1k Downloads
To compare cardiovascular and respiratory responses to different spontaneous breathing trials (SBT) in difficult-to-wean patients using T-piece and pressure support ventilation (PSV) with or without positive end-expiratory pressure (PEEP).
Prospective physiological study. Fourteen patients who were monitored with a Swan-Ganz catheter and had failed a previous T-piece trial were studied. Three SBTs were performed in random order in all patients: PSV with PEEP (PSV-PEEP), PSV without PEEP (PSV-ZEEP), and T-piece. PSV level was 7 cmH2O, and PEEP was 5 cmH2O. Inspiratory muscle effort was calculated, and hemodynamic parameters were measured using standard methods.
Results [median (and interquartile range)]
Most patients succeeded in the PSV-PEEP (11/14) and PSV-ZEEP (8/14) trials, but all failed the T-piece trial. Patient effort was significantly higher during T-piece than during PSV with or without PEEP [esophageal pressure-time product was 292 (238–512), 128 (58–299), and 148 (100–465) cmH2O·s/min, respectively, p < 0.05]. Left ventricular heart failure was observed in 11 of the 14 patients during the T-piece trial. Pulmonary artery occlusion pressure and respiratory rate were significantly higher during T-piece than with PSV-PEEP [21 (18–24) mmHg versus 17 (14–22) mmHg, p < 0.05 and 27 (21–35) breaths/min versus 19 (16–29) breaths/min, p < 0.05 respectively]. Tidal volume was significantly lower during the T-piece trial.
In this selected population of difficult-to-wean patients, PSV and PSV plus PEEP markedly modified the breathing pattern, inspiratory muscle effort, and cardiovascular response as compared to the T-piece. Caregivers should be aware of these differences in SBT as they may play an important role in weaning decision-making.
KeywordsWeaning from mechanical ventilation Spontaneous breathing trial Pressure support ventilation Heart failure
B.C. was supported by grants from the Instituto de Salud Carlos III (expedient CM04/00096, Ministerio de Sanidad) and the Instituto de Recerca Hospital de la Santa Creu i Sant Pau.
- 8.Esteban A, Alia I, Gordo F, Fernandez R, Solsona JF, Vallverdu I, Macias S, Allegue JM, Blanco J, Carriedo D, Leon M, de la Cal MA, Taboada F, Gonzalez de Velasco J, Palazon E, Carrizosa F, Tomas R, Suarez J, Goldwasser RS (1997) Extubation outcome after spontaneous breathing trials with T-tube or pressure support ventilation The Spanish Lung Failure Collaborative Group. Am J Respir Crit Care Med 156:459–465PubMedGoogle Scholar
- 9.Ezingeard E, Diconne E, Guyomarc’h S, Venet C, Page D, Gery P, Vermesch R, Bertrand M, Pingat J, Tardy B, Bertrand JC, Zeni F (2006) Weaning from mechanical ventilation with pressure support in patients failing a T-tube trial of spontaneous breathing. Intensive Care Med 32:165–169CrossRefPubMedGoogle Scholar
- 13.Cabello B, Mancebo J (2006) Cardiovascular and Respiratory Alterations during Different Spontanous Breathing Trials The role of congestive heart failure. Am J Respir Crit Care Med 3:A40Google Scholar
- 16.Fishman A (1985) Pulmonary Circulation Handbook of physiology. The respiratory system Vol I. Circulation and nonrespiratory functions. American Physiological Society, Bethesda, pp 93–166Google Scholar
- 36.Bernard GR, Artigas A, Brigham KL, Carlet J, Falke K, Hudson L, Lamy M, Legall JR, Morris A, Spragg R (1994) The American-European Consensus Conference on ARDS. Definitions, mechanisms, relevant outcomes, and clinical trial coordination. Am J Respir Crit Care Med 149:818–824Google Scholar