Insufficiency of plasmatic arginine/homoarginine during the initial postoperative phase among patients with tumors affecting the medulla oblongata heightens the likelihood of neurogenic pulmonary edema following surgery.

BACKGROUND: This prospective clinical study aims to investigate the fluctuations of neurotransmitters in peripheral venous blood during the perioperative period and to identify independent predictors for postoperative neurogenic pulmonary edema (NPE) in patients with medulla oblongata-involved tumors.

MATERIALS AND METHODS: Peripheral venous blood samples of the enrolled patients at 7 perioperative time points, as well as their medical records and radiologic data were collected. High-performance liquid chromatography-tandem mass spectrometry was utilized to detect the concentrations of 39 neurotransmitters in these samples. The study applied univariate and multivariate generalized estimating equation (GEE) logistic regression analyses to explore independent predictors of postoperative NPE, and one-way repeated-measures ANOVA to compare the concentrations of the same neurotransmitter at different perioperative time points.

RESULTS: The study included 36 patients with medulla oblongata-involved tumors from January to December 2019, and found that 13.9% of them experienced postoperative NPE. The absence of intraoperative use of sevoflurane (P=0.008), decreased concentrations of arginine (P=0.026) and homoarginine (P=0.030), and prolonged postoperative tracheal extubation (P<0.001) were identified as independent risk factors for postoperative NPE in medulla oblongata-involved tumor patients. Pairwise comparison analysis revealed that the perioperative decreases in arginine and homoarginine concentrations mainly occurred within the postoperative 8 hours.

CONCLUSION: This study demonstrates that NPE is not uncommon in patients with medulla oblongata-involved tumors. The absence of intraoperative use of sevoflurane, decreased concentrations of plasmatic arginine and homoarginine, and prolonged postoperative tracheal extubation are independent predictors of postoperative NPE. These two neurotransmitters' concentrations dropped mainly within the early postoperative hours and could serve as potential early warning indicators of postoperative NPE in clinical practice.