Background: An alternation of sympathetic and vagal nervous activity has been suggested to be one possible mechanism of neurogenic pulmonary edema (NPE) in patients with subarachnoid hemorrhage (SAH). The study aimed to explore if sympathovagal modulation assessed by frequency domains of heart rate variability (HRV) is associated with impending NPE in patients with SAH.
Methods: Two hundred forty-eight consecutive spontaneous SAH adult patients were included in this single-center cohort study. A continuous 10-min electrocardiography for HRV analysis was recorded. The patients were stratified into NPE and non-NPE based on serially clinical and radiologic findings within 24 h. Seven frequency domains of HRV were compared between these 2 groups.
Results: Compared to the non-NPE (n = 212), the NPE (n = 36) had significantly higher mean arterial pressure, higher World Federation of Neurological Surgeons (WFNS) class, higher Hunt-Hess scale, lower total power (TP), lower very low-frequency component, lower low-frequency component, lower normalized low-frequency component (LF %), higher normalized high-frequency component, and lower low-frequency component/high-frequency component ratio. Multiple logistic regression model identified WFNS class (OR 4.048; 95 % CI 1.589-10.311), LF % (OR 0.933; 95 % CI 0.910-0.958), and TP (OR 0.995; 95 % CI 0.992-0.998) as the significant variables associated with occurrence of NPE. The area under receiver operating characteristic curves of LF % and TP were found to be 0.838 (95 % CI 0.774-0.901) and 0.653 (95 % CI 0.557-0.749), respectively.
Conclusion: Loss of cardiac variability and depressed sympathovagal modulation, represented by TP and LF %, may predict the development of NPE in the early stage in patients with SAH.
Keywords: Heart rate variability; Heart-brain relationship; Pulmonary edema; Subarachnoid hemorrhage.