# Effect of general anesthesia on postoperative pulmonary embolism

## TL;DR

This study shows that longer general anesthesia, especially over 3 hours, increases the risk of post-surgery blood clots in the lungs.

## Contribution

The study identifies prolonged general anesthesia duration as a novel risk factor for postoperative pulmonary embolism.

## Key findings

- Prolonged general anesthesia significantly increases the risk of postoperative pulmonary embolism.
- Anesthesia type and regional anesthesia duration were not associated with pulmonary embolism occurrence.
- PE incidence was four times higher for general anesthesia lasting over 3 hours compared to shorter durations.

## Abstract

The influence of anesthesia type and duration on the occurrence of pulmonary embolism (PE) after surgery remains controversial. This study investigates the association between anesthesia type and duration with postoperative PE.

A retrospective cohort of adult patients undergoing surgery from May 2020 to August 2024 at large-scale general hospitals was analyzed. Multivariable logistic regression models were employed to adjust for potential confounders, and sensitivity analyses (using overlap weighting and array approach) were performed to validate the findings.

A total of 178,052 patients were included in the analysis, of whom 91 developed PE after surgery. The median duration of general anesthesia (GA) was 1.72 h, with an interquartile range (IQR) of 1.17–2.52 h. The median duration of regional anesthesia was 1.54 h, with an IQR of 1.20–2.03 h. Anesthesia type and the duration of regional anesthesia were not associated with PE occurrence (adjusted odds ratio [aOR] [95% confidence interval, CI], 1.148 [0.671–2.098], p = 0.631), (aOR [95% CI], 1.117 [0.498–1.557], p = 0.738). The rates of PE consistently increased with GA prolongation (aOR [95% CI], 1.308 [1.176–1.432], p < 0.001). Compared with GA durations < 3 h, prolonged anesthesia was significantly associated with increased PE incidence (aOR [95% CI], 4.398 [2.585–7.565], p < 0.001). These findings were also confirmed by sensitivity analyses.

Our study demonstrates that prolonged GA, particularly > 3 h, significantly increases the risk of PE.