Effect of Inhaled Volatile and IV Anesthetics on Biological Markers of Inflammation in Adult ICU and Thoracic Surgical Patients: A Systematic Review and Meta-Analysis.

Objectives: Inhaled anesthetics may reduce alveolar and systemic inflammation in surgical and critically ill patients. This study aimed to perform a systematic review and meta-analysis comparing the effect of inhaled volatile and IV anesthetics on alveolar and plasma cytokines in patients with surgical or medical acute lung injury.

Data Sources: Medline, Embase, and Cochrane CENTRAL databases from 2000 to July 2021.

Study Selection: Randomized control trials, prospective, and retrospective observational studies comparing inhaled volatile to IV anesthetics in ventilated adult patients with acute lung injury from lung resection or critical illness.

Data Extraction: A systematic review and meta-analysis was performed. Primary outcome was alveolar inflammatory cytokines levels that were meta-analyzed using a random effects model. Secondary outcomes were plasma inflammatory cytokine levels, mortality, pulmonary complications, and duration of hospital and ICU stay. The quality of studies was assessed using the Cochrane Risk of Bias tool for randomized control trials and the Cochrane Risk Of Bias In Non-randomized Studies of Interventions tool for retrospective cohort studies.

Data Synthesis: From 2522 screened studies, 28 (27 thoracic surgery and 1 ICU, n = 4175) were included. Meta-analysis of patients undergoing lung resection demonstrated lower levels of alveolar tumor necrosis factor-alpha (TNF-α) (standard mean difference 1.04; 95% CI, 0.32-1.77; p < 0.01; I2 82%) and interleukin (IL)-6 (0.64; 95% CI, 0.52-0.75; I2 0%; p < 0.01) at 1-2 hours in the inhaled anesthesia group, with no difference in other cytokines at various time points. The single ICU study demonstrated lower plasma TNF-α and IL-6 and alveolar TNF-α, IL-6, and IL-8 at 48 hours in patients sedated with sevoflurane compared with midazolam. Clinical outcomes were infrequently reported.

Conclusions: Limited evidence suggests that inhaled anesthesia may reduce proinflammatory cytokines TNF-α and IL-6 during lung resection and critical illness. Further studies are needed to clarify its effects on biological markers and clinical outcomes.