Intraoperative Oxygen Consumption in Lung Resection Converges to 1 MET Regardless of Preoperative Status: Study

How much does preoperative metabolic fitness actually influence a patient’s intraoperative oxygen demand during lung resection surgery? As perioperative management grows more precise, understanding real-world oxygen consumption (VO₂) is critical for tailoring care and optimizing outcomes.

Study Overview: Integrating CPET with Intraoperative Monitoring

Researchers performed a retrospective analysis involving 32 adults who underwent lung resection under general anesthesia. Every patient had a preoperative cardiopulmonary exercise test (CPET), measuring VO₂ at rest, at the anaerobic threshold, and at peak exertion. During surgery, real-time intraoperative VO₂ was estimated using data from anesthetic machines (minute ventilation and inspired/end-tidal oxygen fractions).

Main Findings: Intraoperative VO₂ Consistently Suppressed

The analysis revealed a striking convergence of intraoperative VO₂ values:

Preoperative resting VO₂ averaged 1.6 ± 0.4 METs

Intraoperative VO₂ averaged 1.1 ± 0.2 METs

The average reduction from preop rest to intraop period was –29%

Crucially, regardless of each patient’s preoperative metabolic profile, intraoperative VO₂ converged toward ~1 MET. There was a strong correlation between higher preoperative VO₂ and a greater absolute reduction under anesthesia, but not between preoperative and intraoperative values themselves.

Clinical Implications: Rethinking Oxygen Delivery Targets

These data suggest that, for lung resection surgery under general anesthesia, metabolic demand is consistently suppressed below preoperative resting levels. This raises important questions:

Is routine augmentation of oxygen delivery (DO₂) always warranted during these cases?

Could focusing exclusively on delivery without considering demand lead to overtreatment or unnecessary interventions?

The findings point to the value of integrating both preoperative metabolic assessment and real-time intraoperative monitoring for more individualized hemodynamic management.

Additional Insights: Regional Blocks and Measurement Validity

Patients receiving thoracic regional blocks required significantly less opioid and had lower heart rates, but their intraoperative VO₂ was not statistically different from those without blocks. This suggests that, despite improved analgesia and lower sympathetic tone, the overall suppression of metabolic demand by anesthesia is dominant.

The study also carefully validated its intraoperative VO₂ estimation method, accounting for variables such as one-lung ventilation and dead space, and performed sensitivity analyses using alternative normalization strategies.

Limitations and Future Directions

As an exploratory, retrospective study, these results need confirmation in larger, prospective cohorts. The study excluded patients with significant anemia or lactic acidosis and relied on indirect estimation of VO₂. The impact of brief perioperative metabolic surges or acute complications was not addressed.

Conclusion

Intraoperative oxygen consumption during lung resection surgery converges to a narrow, low range—regardless of preoperative metabolic fitness. These insights challenge the assumption that higher preoperative VO₂ translates to higher intraoperative demand, and set the stage for outcome-driven research on personalized oxygen delivery targets.

Key points

Intraoperative VO₂ during lung resection surgery averages about 1.1 METs, consistently below preoperative resting VO₂.

Preoperative metabolic fitness does not predict intraoperative oxygen demand.

Higher baseline VO₂ is linked to a greater anesthesia-induced reduction, but not a higher intraoperative VO₂.

Thoracic regional blocks lower opioid needs and heart rate but do not significantly change intraoperative VO₂.

These findings suggest the need to consider both oxygen delivery and demand in perioperative management.

Citation:

Oh C, Park S, Lee S, et al. Preoperative and intraoperative oxygen consumption in patients undergoing lung resection surgery: a retrospective study using cardiopulmonary exercise test and intraoperative data. BMC Anesthesiol. 2026; [in press]. https://doi.org/10.1186/s12871-026-03912-x