Weaning from mechanical ventilation using pressure support and T-tube induces ventricular arrhythmia in cardiac patients

Introduction

Weaning from mechanical ventilation (MV) can be associated with cardiac arrhythmias. Few studies are found comparing their occurrence during weaning with pressure support ventilation (PSV) and T-tube (TT) in patients with and without heart disease.

Objective

To evaluate the occurrence of arrhythmias in these groups of patients during PSV and TT.

Methods

Patients without (group 1) and with (group 2) heart disease, under mechanical ventilation for at least 48 hours, were observed during 30 min of PSV or TT, in a random order. Variables analyzed were: age, APACHE score, length of stay in the ICU (LOS), and cardiorespiratory variables including respiratory rate, rapid shallow breathing index (f/VT), maximum inspiratory (PImax) and expiratory (PEmax) pressure. A continuous ECG was recorded by the Holter method. For statistical analyses, repeated-measures ANOVA or ANOVA on ranks was used.

Results

Twenty-two patients were studied, 13 in group 1 and nine in group 2. Comparisons between groups 1 and 2 showed: no differences in APACHE score (23 ± 4; 23 ± 8, not significant), PImax (32 ± 19; 28 ± 12 cmH₂O, not significant) and PEmax (24 ± 10; 20 ± 7 cmH₂O, not significant); f/VT was greater in cardiac patients during TT (PSV: 48 ± 25 versus 41 ± 18; TT: 42 ± 18 versus 57 ± 20, ANOVA, P < 0.05), as well as the respiratory rate (PSV: 21 ± 6 versus 20 ± 5; TT: 22 ± 6 versus 25 ± 6, ANOVA, P < 0.05). The occurrence of ventricular arrhythmias (median and interquartile ranges), respectively, in PSV and TT in group 1 were 1 (0–13) vs 1 (0–5.5) and in group 2 were 3 (0.5–87) vs 21 (4–61) (ANOVA, P < 0.05).

Conclusions

During weaning from MV, cardiac patients showed a higher respiratory rate and higher f/VT during TT when compared with PSV, as well as a greater occurrence of ventricular arrhythmias in both methods when compared with noncardiac patients.