Heated Humidified Oxygen in PACU Patients

This study aims to determine whether heated and humidified oxygen therapy, compared with conventional room-temperature oxygen therapy, reduces the incidence of early hypoxemia in adult patients recovering from general anesthesia in the Post-Anesthesia Care Unit (PACU). Hypoxemia is a common and potentially life-threatening complication during PACU recovery, resulting from residual anesthetics, decreased upper airway muscle tone, atelectasis, and suppression of hypoxic pulmonary vasoconstriction (HPV). Heated and humidified oxygen may offer benefits by preserving optimal HPV function, protecting airway mucosa, and reducing respiratory resistance. This is a prospective, multicenter, randomized, superiority trial with a parallel-group design. A total of 2,000 adult patients (ASA class I-III) undergoing general anesthesia will be enrolled and randomly assigned in a 1:1 ratio to receive either heated and humidified oxygen (37°C, 5 L/min via face mask) or room-temperature oxygen (room temperature, 5 L/min via face mask). The primary outcome is the incidence of hypoxemia, defined as SpO₂ ≤ 90% lasting ≥ 5 seconds, within 10 minutes after initiation of the intervention. Secondary outcomes include severe hypoxemia (SpO₂ ≤ 85%), requirement for airway interventions, lowest SpO₂ value, PACU length of stay, postoperative shivering, and agitation. Safety outcomes include nasal discomfort, epistaxis, and device-related adverse events.