Study Reveals: Both Compressible and Non-Compressible Warming Systems Equally Effective in Off-Pump Heart Surgery

Why Temperature Management in Cardiac Surgery Matters

Maintaining a stable core temperature during cardiac surgery is crucial. Off-pump coronary artery bypass (OPCAB) procedures, which avoid the use of a heart-lung machine, pose unique challenges for temperature control because they lack active warming from the bypass circuit. Inadequate temperature management can lead to hypothermia, causing complications like impaired coagulation, increased infection risk, and slower recovery.

The Devices Under the Microscope

This study from University Hospital Bonn set out to compare two types of underbody forced-air warming systems used during off-pump heart surgery:

Compressible blankets: Soft, inflatable, but can flatten under patient weight, potentially reducing heat transfer.

Non-compressible blankets: Rigid design maintains its shape, theoretically offering more even and effective warmth.

Both systems were set at 43°C, and all patients also received warmed IV fluids.

How the Study Was Done

Researchers retrospectively analyzed 100 adult patients who underwent elective off-pump heart surgery between 2021 and 2023. The patients were split into two groups based on which warming system was in use at the time. Core temperatures were continuously monitored from anesthesia induction to ICU transfer.

The main measure? The largest drop in core temperature from each patient's baseline during surgery.

What Did the Findings Show?

Surprisingly, the study found no significant difference between the two warming systems:

The median core temperature drop was 0.40°C for the non-compressible group and 0.50°C for the compressible group.

Both groups maintained safe end-of-surgery temperatures above 36°C.

Rates and severity of intraoperative hypothermia were similar.

The only independent predictor of temperature decline was a higher baseline temperature at the start—not the choice of warming device.

Does the Warming System Choice Matter?

From a clinical perspective, both systems did the job. The findings suggest that hospitals can choose either device based on preference, cost, or sustainability concerns, without worrying about compromising patient safety in terms of temperature control.

Quick Takeaways

Both compressible and non-compressible underbody warming systems are equally effective at maintaining core temperature in off-pump cardiac surgery.

Most patients finished surgery with a safe core temperature above 36°C.

Device choice did not impact hypothermia rates or recovery times.

Higher baseline temperature predicted greater intraoperative temperature drops.

Environmental and cost factors may guide device selection, not clinical performance.

Citation:

Rösler, O., Bakhtiary, F., Bode, C., Coburn, M., Velten, M., & Piekarski, F. (2026). Influence of Non-Compressible Versus Compressible Underbody Forced-Air Warming Systems on Core Temperature in Off-Pump Cardiac Surgery. Journal of Cardiothoracic and Vascular Anesthesia, 40, 1659–1667. https://doi.org/10.1053/j.jvca.2025.12.009