Impact of pharmacological interventions on intrapulmonary shunt during one-lung ventilation in adult thoracic surgery: a systematic review and component network meta-analysis

Br J Anaesth. 2023 Jan;130(1):e92-e105. doi: 10.1016/j.bja.2022.08.039. Epub 2022 Oct 26.


Background: Intrapulmonary shunt is a major determinant of oxygenation in thoracic surgery under one-lung ventilation. We reviewed the effects of available treatments on shunt, Pao2/FiO2 and haemodynamics through systematic review and network meta-analysis.

Methods: Online databases were searched for RCTs comparing pharmacological interventions and intrapulmonary shunt in thoracic surgery under one-lung ventilation up to March 30, 2022. Random-effects (component) network meta-analysis compared 24 treatments and 19 treatment components. The Confidence in Network Meta-Analysis (CINeMA) framework assessed evidence certainty. The primary outcome was intrapulmonary shunt fraction during one-lung ventilation.

Results: A total of 55 RCTs were eligible for systematic review (2788 participants). The addition of N2O (mean difference [MD]=-15%; 95% confidence interval [CI], -25 to -5; P=0.003) or almitrine (MD=-13%; 95% CI, -20 to -6; P<0.001) to propofol anaesthesia were efficient at decreasing shunt. Combined epidural anaesthesia (MD=3%; 95% CI, 1-5; P=0.005), sevoflurane (MD=5%; 95% CI, 2-8; P<0.001), isoflurane (MD=6%; 95% CI, 4-9; P<0.001), and desflurane (MD=9%; 95% CI, 4-14; P=0.001) increased shunt vs propofol. Almitrine (MD=147 mm Hg; 95% CI, 58-236; P=0.001), dopexamine (MD=88 mm Hg; 95% CI, 4-171; P=0.039), and iloprost (MD=81 mm Hg; 95% CI, 4-158; P=0.038) improved Pao2/FiO2. Certainty of evidence ranged from very low to moderate.

Conclusions: Adding N2O or almitrine to propofol anaesthesia reduced intrapulmonary shunt during one-lung ventilation. Halogenated anaesthetics increased shunt in comparison with propofol. The effects of N2O, iloprost, and dexmedetomidine should be investigated in future research. N2O results constitute a research hypothesis currently not backed by any direct evidence. The clinical availability of almitrine is limited.

Systematic review protocol: PROSPERO CRD42022310313.

Keywords: intrapulmonary shunt; meta-analysis; one-lung ventilation; oxygenation; thoracic surgery.

Publication types

  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Adult
  • Almitrine
  • Humans
  • Iloprost
  • Network Meta-Analysis
  • One-Lung Ventilation* / methods
  • Propofol*
  • Thoracic Surgery*


  • Almitrine
  • Iloprost
  • Propofol