Vital signs during complication-free recovery after major surgery: a retrospective analysis

Continuous vital sign monitoring (CVSM) is superior to intermittent manual vital sign assessment in detecting deviations, but alert thresholds have limited evidence, as a strong definition of physiologically normal variations are lacking. Consequences of too few alerts are missed detections of oncoming complications, and too many alerts result in over-alerting and over-treatment. This study aimed to describe duration and deviation of vital signs in postoperative patients without complications when monitored continuously. Adult patients admitted to the general ward after major surgery were included. Continuous wireless vital sign monitoring (CVSM) was performed during the early postoperative period, with data collection blinded to ward nurses. For peripheral oxygen saturation (SpO₂), systolic blood pressure, heart rate, and respiratory rate, the longest consecutive durations outside predefined thresholds were identified. The primary outcome was the longest consecutive duration of SpO₂ < 88%. A total of 600 patients were analyzed and of these, 277 patients had no complications of any kind. The longest sustained episodes with SpO₂ < 88% were median 9 min [IQR 2-31 min]. The maximum length of other vital sign sustained deviations had the following median duration in minutes: SpO₂ < 92%: 58[6 -129], HR > 110/min: 3 [0-13], HR < 50/min: 0 [0-1], RF > 24/min: 1 [0-4] and RF < 11/min: 4 [2-12]. Sustained episodes of severe desaturations, tachycardia and tachypnea were short, but moderate desaturations frequent. These findings indicate that vital signs in complication free patients should be carefully analyzed when monitored continuously after major surgery.