Orthostatic intolerance following posterior lumbar interbody fusion: incidence, risk factors, and impact on postoperative recovery: a prospective cohort study.

Abstract

Despite the well-established consensus about the importance of early ambulation, the causes of orthostatic intolerance and its impact on patient recovery after posterior lumbar interbody fusion (PLIF) remain poorly understood. To determine the incidence of orthostatic intolerance and relevant risk factors after PLIF in an enhanced recovery after surgery (ERAS) program. A prospective observational cohort study. This study investigated perioperative data collected from 378 patients who underwent PLIF at one center between September 2023 and July 2024. Patients' postoperative orthostatic intolerance symptoms were recorded and graded by a standardized evaluation scale. The occurrence of any symptom that resulted in termination of ambulation (dizziness, nausea, vomiting, a feeling of heat, visual disturbances, hypotension, and syncope) was classified as orthostatic intolerance. Possible risk factors were identified through univariate and multivariate analysis. The length of postoperative hospitalization, catheterization, and ambulation delay in orthostatic intolerance patients versus orthostatic tolerant patients was compared. For orthostatic intolerance patients, the median time to first attempted ambulation was 26.0 (IQR: 20.8-31.2) hours after surgery. Overall, the observed incidence of orthostatic intolerance was 15.3%. Univariate analysis showed that a higher incidence of orthostatic intolerance was associated with history of orthostatic intolerance (6 vs. 13, p=.044), low hemoglobin on postoperative day 1 (103.8±14.8g/L vs. 110.7±13.3g/L, p<.001), and high postoperative back pain visual analog scale (VAS) scores while supine (4.0 [2.0] [4.0±1.8] vs. 3.0 [1.0] [3.4±1.8], p=.015). Multivariate analysis through logistic regression controlling for covariates established the same three variables as independent risk factors: history of orthostatic intolerance (OR=3.029, 95% CI 1.021-8.988, p=.046), low hemoglobin on postoperative day 1 (OR=2.890, 95% CI 1.566-5.334, p<.001), and high postoperative back pain VAS scores while supine (OR=1.218, 95% CI 1.030-1.441, p=.021). Overall, orthostatic intolerance patients had a longer postoperative hospital stay (6.0 [2.0] [6.3±1.8] vs. 6.0 [2.0] [5.8±1.8], p=.013), catheterization period (24.1 [5.2] [26.0±8.9] vs. 22.6 [4.7] [22.8±4.0], p=.042), and ambulation delay (48.2 [6.3] [48.7±7.8] vs. 25.0 [4.5] [25.0±3.9], p<.001) than orthostatic tolerance patients. However, there were no clinically meaningful differences regarding postoperative hospital stay or catheterization period found between the two groups in this study. Orthostatic intolerance is a common complication that prevents early ambulation in ERAS programs after PLIF. Careful monitoring of postoperative hemoglobin levels and administration of postoperative analgesia may reduce the incidence of orthostatic intolerance and promote early ambulation.