Effects of theophylline therapy on respiratory muscle strength in patients with prolonged mechanical ventilation: A retrospective cohort study

Mechanical ventilation may cause diaphragm weakness an effect termed ventilator-induced diaphragm dysfunction (VIDD). The prevalence of VIDD among patients receiving mechanical ventilation is very high, with the degree of diaphragmatic atrophy being associated with the length of mechanical ventilation. Theophylline is known to increase diaphragmatic contractility and reduce fatigue, so in this study, we evaluated the effect of theophylline in patients with prolonged mechanical ventilation. Patients who depended on mechanical ventilation were included in the study. We compared the maximum inspiratory pressure (PImax) values, rapid shallow breathing index (RSBI) values, and successful weaning rates of theophylline-treated and non-theophylline-treated patients. Eighty-four patients received theophylline and 76 patients did not. These 2 groups’ clinical characteristics, including their PImax and RSBI at initial admission, were similar. The results showed that the theophylline-treated group had significantly better PImax and RSBI, with a higher last PImax (30.1 ± 9.7 cmH(2)O vs 26.9 ± 9.1 cmH(2)O; P = .034) and lower last RSBI (107.0 ± 68.4 vs 131.4 ± 77.7; P = .036). The improvements to each respective patient's PImax and RSBI were also significantly higher in the theophylline-treated group (PImax: 20.1 ± 5.7% vs 3.2 ± 1.1%, P = .005; RSBI: 11.2 ± 3.0% vs 2.7 ± 1.6%, P = .015). The weaning success rate of the theophylline-treated group was also higher, but not significantly so. Theophylline might improve respiratory muscle strength in patients with prolonged mechanical ventilation and it needs further prospective studies to confirm.