Use of inspiratory strength training to wean six patients who were ventilator-dependent

Patients who are unable to wean from mechanical ventilation (MV) after resolution of critical illness or surgery risk increased morbidity and death and consume a disproportionate amount of intensive care unit resources. Decreased inspiratory muscle strength is often cited as a major factor contributing to prolonged MV. The purpose of this case report is to describe the rationale and application of inspiratory strength training (IST) as an adjunct to lengthen unassisted breathing trials and to ultimately wean patients with chronic mechanical ventilator dependency.

Six patients who had been ventilator-dependent for 18 to 221 days (mean of 72 days) after surgery and were diagnosed with "failure to wean" performed low-repetition, high-resistance breathing exercises that were coupled with increasing time off the ventilator.

All 6 patients were weaned from the ventilator in 9 to 28 days (mean of 17 days). The patients' training pressure increased from a mean of 9.3 cm/H2O to 27.5 cm/H2O, for an increase of 195%. The volitional maximum inspiratory pressure (MIP) increased from a mean of 22.5 cm/H2O to 54 cm/H2O, for a 140% gain in pressure.

Although it is not clear why the patients appeared to benefit from IST, possible explanations include: (1) addressing inspiratory muscle pump dysfunction, (2) standardization of breathing patterns, 3) routinization of the patients' unassisted breathing trials, and (4) nonspecific training effects. Future research should address these possibilities when attempting to understand the effects of IST in the weaning of patients with chronic ventilator dependency.