PURPOSE:Sleep disturbance is an important contributor to morbidity in the intensive care unit. Patient-ventilator asynchrony is thought to be an important factor causing sleep disturbance in mechanically ventilated patients. The role of patient-ventilator asynchrony causing arousals from sleep has not been fully elucidated.
METHODS:Patients were recruited from the intensive care unit at the San Giovanni Battista-Molinette Hospital (University of Turin). The ethics committee approved the protocol and all patients provided written informed consent. Specific details outlining the methods used in this study have been previously published (Crit Care Med 2007; 35:1048–1054). Patients were randomized to either pressure support (PSV) or proportional assist ventilation (PAV) on the first night and crossed over to the alternate ventilatory modality the subsequent night. Measurements included polysomnography, airflow, esophageal and airway pressure. Arousals were identified from polysomnographic data. Patient-ventilator asynchronies including ineffective efforts, auto-triggering, delayed cycling and delayed triggering were identified during the one minute interval preceding arousals and during one minute periods of sleep without arousals. Data were compared using chi-squared analysis.
RESULTS:Data from eight patients were examined. Preliminary results show that during both PAV and PSV asynchronies occurred in the minute preceding an arousal more frequently than during the period of sleep not associated with an arousal (PAV 10% vs. 4%; p < 0.05; PSV 24% vs. 16%; p < 0.01). Asynchronies preceding arousals occurred more frequently during PSV than during PAV (24% vs. 10%; p < 0.001).
CONCLUSION:These preliminary results suggest patient-ventilator asynchrony plays a minor role in sleep disruption, accounting for 24% and 10 % of arousals from sleep during PSV and PAV respectively. These results are comparable in magnitude to the effect of noise and patient-care activities on sleep disturbance in intensive care unit patients (Am J Respir Crit Care Med. 2003;167(5):708–15). Further work is required to delineate other factors contributing to sleep disruption in mechanically ventilated patients.
CLINICAL IMPLICATIONS:Improving sleep quality for ventilated patients likely requires a multi-faceted approach which should include enhancing patient-ventilator synchrony.
DISCLOSURE:Christopher Hergott, No Financial Disclosure Information; No Product/Research Disclosure Information