Automated end-tidal control versus manual regulation in low-flow volatile anesthesia: a systematic review and meta-analysis

Clinical Snapshot

Key Findings

• P Value: Anesthesia duration p=0.99, Procedural duration p=0.80, Sevoflurane consumption p=0.31

• Effect Size: Anesthesia duration SMD -0.00 min, Procedural duration SMD 0.04 min, Sevoflurane consumption SMD -0.32 mL

• Primary Outcome: No significant difference in anesthesia duration, procedural duration, or sevoflurane consumption between automated and manual control

• Nnt Or Sensitivity: Not applicable - no significant treatment effects demonstrated

• Confidence Interval: Anesthesia duration 95% CI [-0.34, 0.34], Procedural duration 95% CI [-0.26, 0.33], Sevoflurane 95% CI [-0.94, 0.29]

Clinical Application

Technology exists but evidence insufficient to support routine implementation over manual control Would require TGA approval for automated systems. Current ANZCA guidelines support manual control. Cost-effectiveness unclear given lack of demonstrated clinical benefit Limited applicability due to very low certainty evidence and significant heterogeneity between studies

Abstract

BACKGROUND: In low-flow anesthesia, automated monitoring of end-tidal oxygen (etO2) and end-tidal anesthetic agents (etAA) has been favored to reduce clinicians' cognitive workload during anesthesia maintenance. This systematic review, therefore, aimed to determine the comparative efficacy and safety of automated end-tidal controlled anesthesia (etCA) versus manually controlled anesthesia (MCA). METHODS: An electronic search was conducted across four databases: PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and Scopus. The retrieved references were then analyzed against the studies' screening and eligibility criteria before the full articles were included in the study. The Review Manager (RevMan 5.4.1) was then used to conduct the statistical analysis of the reported outcomes. RESULTS: The electronic search retrieved 965 articles, among which 10 were included in this review. The studies included a pooled sample size of 1269 who underwent surgical procedures under low-flow anesthesia. The analyzed evidence suggests with low certainty that the type of anesthesia control may not have any significant effect on both the anesthesia duration (SMD - 0.00 min; 95% CI [-0.34, 0.34] p = 0.99) and the procedural duration MCA (SMD 0.04 min; 95% CI; 95% CI [-0.26, 0.33] p = 0.80). Moreover, we found with low certainty in the evidence that the amount of sevoflurane consumed may not be significantly different between etCA and MCA (SMD - 0.32 mLs; 95% CI [-0.94, 0.29] p = 0.31). Our narrative synthesis indicated that etCA can potentially improve anesthesia delivery by reducing the required anesthetist interventions and ensuring stable and accurately administered anesthetics. CONCLUSION: This review found very low-quality evidence suggesting that the type of anesthesia control may not significantly affect anesthesia delivery parameters, such as the amount of anesthesia consumed and procedural and anesthesia duration. The analyses, however, had significant heterogeneity, making the estimates highly unreliable. On the other hand, some studies indicate potential advantages of using etCA, such as reducing the number of interventions required during anesthesia; however, the evidence remains limited, preventing a full exploration of these advantages.

References

1. 1.Shaban, A., Zaki, H. A., Shaban, E. E., Shaban, A., Elkandow, A., Abdelrahim, M. G., El-Abd, A. S., & Abosamak, M. F. (2026). Automated end-tidal control versus manual regulation in low-flow volatile anesthesia: a systematic review and meta-analysis. BMC Anesthesiology. https://doi.org/10.1213/ANE.0000000000001394