呼吸器・呼吸器内科

Delirium during Noninvasive Positive Pressure Ventilation: A Prospective Observational Study

Abstract

Mutsuo Onodera, Nao Okuda, Masayo Izawa and Masaji Nishimura

Background: Noninvasive positive pressure ventilation (NPPV) has been used to treat acute respiratory failure in intensive care units (ICU), while some patients need tracheal intubation because of not only underlying diseases but also delirium. Delirium in patients being mechanically ventilated via endotracheal tubes has been subject to concern and investigated in numerous studies, however in patients receiving NPPV has been little studied. The aim of the study was to discover the incidence of delirium in NPPV patients.

Methods: Adult patients who received NPPV were enrolled. Basic profiles of patients, underlying diseases, indication of NPPV, duration of NPPV, length of stay in ICU, NPPV settings, administration of sedative agents and outcome were collected. Delirium was diagnosed with the Confusion Assessment Method for the ICU (CAM-ICU) by attending nurses.

Results: Forty-three adult patients who received NPPV were enrolled. For all patients, NPPV was applied via full face mask. The diagnosis of 30 patients (69%) was cardiogenic pulmonary edema. Delirium was observed in 16 patients (37%). Patients with delirium were older than those without (78.4 vs. 69.5 years old, p = 0.031). Thirty-one patients (72%) were successfully weaned from NPPV. NPPV failure rate was 38% for patients with delirium and 22% for patients without (p = 0.313). Dexmedetomidine was administered to 26 (61%) patients during NPPV.

A few studies reported the incidence of delirium during NPPV for hypercapnic respiratory failure. We found an incidence of delirium similar to patients with hypercapnic respiratory failure. Dexmedetomidine was most frequently administered because it carried minimal risk of respiratory depression, while we are unable to unconditionally rely on the safety of dexmedetomidine during NPPV.

Conclusions: The incidence of delirium in patients who received NPPV for normocapnic respiratory failure was as high as NPPV for hypercapnic patients. While it was lower than for patients receiving invasive mechanical ventilation.