Reasons for using nitrous oxide in one-lung ventilation, especially for thoracoscopic surgery

Recommendations and considerations for speeding the collapse of the non-ventilated lung during single-lung ventilation in thoracoscopic surgery: a literature review

Video-assisted thoracoscopic thoracic surgery has the advantages of less physical damage, less postoperative pain, and a rapid recovery. Therefore, it is widely used in the clinic. The quality of nonventilated lung collapse is the key point of thoracoscopic surgery. Poor lung collapse on the operative side damages surgical exposure and prolongs the process of surgery. Therefore, it is important to achieve good lung collapse as soon as possible after opening the pleura. Over the past two decades, there have been reports of advances in research on the physiological mechanism of lung collapse and several kinds of techniques for speeding up lung collapse. This review will inform the advances of each technique, make recommendations for reasonable implementation and discuss their controversies and considerations.

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

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.