Cardiac Surgery Outcomes May Depend on the Crystalloid You Choose, Study Finds

Why Fluid Choice Matters During cardiopulmonary Bypass

In the high-stakes world of cardiac surgery, every detail counts-including the fluid used to manage a patient’s blood chemistry during and after cardiopulmonary bypass (CPB). The process of zero-balance ultrafiltration (Z-BUF) helps remove excess fluid and inflammatory mediators near the end of CPB, but the type of crystalloid replacement fluid could make a real difference in patient recovery.

The Study: Comparing Three Common Solutions

A recent study in BMC Anesthesiology enrolled 90 patients undergoing elective cardiac surgery with CPB, dividing them into three groups. Each group received a different fluid during Z-BUF:

Ringer’s solution

Ringer’s lactate

Normal saline

Researchers measured patients’ lactate and pH levels at five key points during the procedure, aiming to see how each solution affected acid–base balance and metabolic stability.

What Did They Find?

Lactate Levels: All groups showed a rise in lactate during surgery, but those given Ringer’s lactate had a predictable, temporary spike immediately after Z-BUF—thanks to the lactate content of the fluid. However, this increase faded quickly and wasn’t significantly different between groups by the end of surgery.

pH Balance: No statistically significant pH differences were found between groups at any time point. Yet, the Ringer’s lactate group experienced the smallest pH drop during the critical filtration period (from 7.38 to 7.37), suggesting better acid–base stability.

Clinical Implication: The smaller pH fluctuation with Ringer’s lactate may keep patients on a more even metabolic keel, potentially reducing the need for corrective interventions and simplifying postoperative care.

Beyond the Numbers: What Does It Mean for Care Teams?

Understanding the unique effects of each fluid helps surgical teams and critical care nurses interpret lab values more accurately and avoid overreacting to temporary changes. For instance, a lactate bump from Ringer’s lactate is expected and not a sign of poor tissue perfusion.

The Takeaway: Personalizing Fluid Choice

While Ringer’s lactate looks promising for pH stability, the study stops short of declaring a clear winner. Larger trials, especially those including patients with liver or kidney disease, are needed to confirm whether these metabolic advantages translate into better recovery or fewer complications.

5 Key Takeaways

Ringer’s lactate caused a temporary but expected jump in lactate levels after filtration—this resolved quickly.

pH fluctuations were smallest with Ringer’s lactate, suggesting better acid–base stability.

No group showed significant differences in final pH or lactate levels—the clinical impact remains to be proven.

For nurses and care teams, knowing the expected lab trends for each fluid can prevent unnecessary interventions.

More research is needed to guide fluid choice for individual patient needs and outcomes.

Citation:

Pabarjay, M., Azarfarin, R., Alizadeh-Ghavidel, A., Hamidi, S.H., Bakhshandeh, H., Tarkhan, F., & Alijanpour, S. (2026). Crystalloid fluids choices during cardiopulmonary bypass, outcomes of acid–base and lactate levels in cardio surgery. BMC Anesthesiology. https://doi.org/10.1186/s12871-026-03711-4