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Updated: Jun 14, 2026
Investigation into Deep Breathing through Measurement of Ventilatory Parameters and Observation of Breathing Patterns
Published on: September 16, 2019
Physiological comparison of three spontaneous breathing trials in difficult-to-wean patients
Belén Cabello1, Arnaud W Thille, Ferran Roche-Campo
1Servei de Medicina Intensiva, Hospital Santa Creu i Sant Pau, C. Sant Quintí 89, 08041, Barcelona, Spain.
Purpose:
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).
Methods:
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 cmH(2)O, and PEEP was 5 cmH(2)O. 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) cmH(2)O x 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.
Conclusion:
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.
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