The effects of thoracic epidural blockade on ventilation-perfusion matching during one-lung ventilation: An exploratory study

Yuxian Wang; Yilin Wei; Guannan Chen; Zhiyao Wang; Yu Fan; Jie Wang; Yuanjun Yang; Di Zhou; Ming Zhong

doi:10.1016/j.jclinane.2024.111678

The effects of thoracic epidural blockade on ventilation-perfusion matching during one-lung ventilation: An exploratory study

J Clin Anesth. 2024 Nov 5:99:111678. doi: 10.1016/j.jclinane.2024.111678. Online ahead of print.

Authors

Yuxian Wang¹, Yilin Wei², Guannan Chen¹, Zhiyao Wang³, Yu Fan³, Jie Wang³, Yuanjun Yang¹, Di Zhou⁴, Ming Zhong⁵

Affiliations

¹ Department of Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China.
² Shanghai Institute of Infectious Disease and Biosecurity, School of Public Health, Fudan University, Shanghai, China.
³ Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China.
⁴ Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China. Electronic address: zhou.di@zs-hospital.sh.cn.
⁵ Department of Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China; Shanghai Institute of Infectious Disease and Biosecurity, School of Public Health, Fudan University, Shanghai, China; Shanghai Key Laboratory of Lung Inflammation and Injury, Shanghai, China. Electronic address: zhong.ming@zs-hospital.sh.cn.

PMID: 39504921
DOI: 10.1016/j.jclinane.2024.111678

Abstract

Objective: Electrical impedance tomography (EIT) enables continuous image acquisition, facilitating real-time measurements of ventilation and perfusion at the clinical bedside. Experimental and clinical studies on controversial effects of thoracic epidural blockade (TEB) with local anesthetics on ventilation-perfusion(V/Q) matching and hypoxia during one lung ventilation (OLV) are rare. The aim of this study was to use EIT to investigate the effects of TEB combined with general anesthesia on pulmonary perfusion distribution and V/Q matching during one-lung ventilation.

Design: Single-centered, prospective, unblinded, randomized, parallel-group clinical trial.

Setting: Surgical suite of a university-affiliated teaching hospital.

Patients: Thirty patients prepared for thoracic surgery were randomly assigned to either the control group or the TEB group, which received a combination of thoracic epidural blockade and general anesthesia.

Measurements: EIT measurements and blood gas analysis were conducted in the lateral position during two-lung ventilation(T₀), 15 min after OLV(T₁), and 15 min after administration of 0.25 % ropivacaine or 0.9 % saline via epidural delivery during OLV(T₂). Hemodynamic and respiratory parameters were recorded, and Dead Space%, Shunt%, and V/Q Match% were calculated based on blood gas analysis and EIT images.

Results: Mean arterial pressure (p < 0.05) significantly decreased 15 min after TEB, while there were no significant changes in heart rate among the 30 patients (p = 0.547). OLV resulted in a significant decrease in arterial oxygen partial pressure/inspired oxygen fraction (PaO₂/FiO₂) from T₀ to T₁ in both groups. The PaO₂/FiO₂ in the TEB group was significantly lower after epidural administration of the local anesthetic (p < 0.05). Shunt- ABG (%) was significantly higher in the TEB group compared to the control group at T₂ (p < 0.05). TEB increased non-ventilated perfusion distribution(p < 0.05), and Shunt-EIT % (p < 0.05) and reduced Matched Region % (p < 0.05), while Dead Space-EIT % remained (p = 0.499).

Conclusions: Based on the contrast-enhanced EIT evaluation of pulmonary perfusion and ventilation, TEB appears to induce a V/Q mismatch in patients undergoing OLV in the lateral position for thoracic surgery.

Trial registration: ClinicalTrials.gov, NCT04730089. Registration on January 25th, 2021.

Keywords: Electrical impedance tomography; One-lung ventilation; Thoracic epidural blockade; Ventilation-perfusion matching.

Associated data

ClinicalTrials.gov/NCT04730089