The objective of this study was to analyze changes in cardiac function using Doppler echocardiogram in critical patients during weaning from mechanical ventilation using two different weaning methods (pressure support and T-tube) and to compare a subgroup of patients: success vs. failure in weaning and patients with vs. without heart disease.

Weaning from mechanical ventilation (MV) involves physiological changes that can overload the cardiorespiratory system due to changes in the interaction between patient and ventilator.

This was a randomized crossover clinical trial that included patients in an intensive care unit (ICU) who had been on MV for more than 48 hours and who were considered ready for weaning. Cardiorespiratory variables, oxygenation, electrocardiogram (ECG) and Doppler echocardiogram findings were analyzed at baseline and after 30 minutes in each trial weaning method (PSV and T-tube). Comparisons were made between PSV and T-tube, weaning success and failure and patients with and without heart disease, using ANOVA and Student's t test. The level of significance was set at p < 0.05.

Inclusion Criteria:

• patients hemodynamically stable
• conscious (Glasgow scale ≥ 13)
• with adequate gaseous exchange (O2 saturation ≥ 95%, fraction of inspired oxygen (FiO2) ≤ 40% and positive end-expiratory pressure (PEEP) = 5
• with no acidosis or alkalosis)
• normal electrolyte levels
• presence of respiratory drive
• informed consent was signed by the patients and/or family members

Exclusion Criteria:

• hemodynamic instability
• severe intracranial disease
• barotrauma

Patients receiving MV for more than 48 hours, who had been admitted to the Intensive Care Unit (ICU), and who met the criteria for weaning from MV according to the parameters previously defined were selected to participate in this study.