Postoperative Delirium and the Association to Continuously Monitored Severe Deviations of Vital Signs at the General Ward After Major Abdominal Surgery.

backgroundDelirium is the most frequent neurological complication after surgery and is associated with increased postoperative morbidity and mortality. The underlying pathophysiology is not fully understood, but is suggested to be multifactorial, including hypoperfusion and hypoxia; however, the role of deviating vital signs prior to postoperative delirium (POD) remains unclear. This study aimed to examine the association between severe physiological deviations detected by continuous wireless monitoring and the occurrence of POD within the first three postoperative days after major abdominal cancer surgery.

methodsIn this prospective substudy, the primary outcome delirium was assessed daily with the validated 3D-CAM questionnaire during the first three postoperative days following major abdominal cancer surgery, and patients were classified into three groups: POD, neurocognitive decline (NCD), and no cognitive impairment (controls). Vital signs (blood pressure, respiratory rate, heart rate, and peripheral oxygen saturation) were continuously monitored for up to 96 h postoperatively. The primary exposure was the cumulative duration of severely deviating vital signs 24 h before POD diagnosis. Secondary exposures included the frequency of sustained severe vital sign deviation episodes.

resultsOf 225 patients with complete 3D-CAM data, 22 (9.8%) developed POD, 73 (32.4%) had NCD, and 130 (57.8%) had no cognitive impairment (controls). The median cumulative duration of vital sign deviations 24 h prior to POD was not significantly different between POD patients and controls (204 min vs. 325 min, p = 0.63). Episodes of sustained tachycardia, bradycardia, and bradypnea in the 24 h prior to POD diagnosis were more frequent in POD patients compared to controls, all p < 0.001. In the 24 h after POD diagnosis, patients with POD also exhibited more frequent episodes of sustained tachypnea, desaturation, tachycardia, and hypertension than controls (all p ≤ 0.005). In NCD patients, deviations were intermediate: bradypnea and bradycardia were more frequent before, and tachycardia, hypotension, hypertension, and desaturation more frequent after the NCD assessment, compared with controls.

conclusionAlthough the cumulative duration of severe vital sign deviations did not differ between POD patients and controls, episodes of sustained severe vital sign deviations were significantly more frequent in POD patients before and after POD diagnosis, suggesting a potential for earlier identification of patients at risk. Whether acting on these signals alters the incidence of delirium was not tested and requires a prospective study. EDITORIAL COMMENT: In this secondary analysis of a prospectively assessed high risk surgical cohort, postoperative vital sign deviations acquired from wireless technology were analysed for possible relations to postoperative delirium development. The findings show that vital sign deviation was observed often before or after delirium development, though it is not yet clear which category or measurement of vital sign deviation would be most likely to be associated with delirium.

trial registrationNCT03491137.