Cardiac output augmentation with fluid resuscitation improves brain tissue oxygenation after severe brain injury

Introduction

The objective of this study was to investigate the relationship between cardiac output response to a fluid challenge and changes in brain tissue oxygen pressure (PbtO₂) in patients with severe brain injury.

Methods

Prospective observational study conducted in a neurological ICU in a university hospital. Seventy-eight fluid challenges were administered to 17 consecutive comatose patients that underwent multimodality monitoring of cardiac output, intracranial pressure (ICP), and PbtO₂. The relationship between cardiac output and PbtO₂ was analyzed with logistic regression utilizing GEE with an exchangeable correlation structure.

Results

Of the 78 fluid boluses analyzed, 34 (44%) resulted in a ≥10% increase in cardiac output. Median absolute (+5.4 vs +0.7 mmHg) and percentage (20% vs 3%) changes in PbtO₂ were greater in cardiac output responders than in nonresponders within 30 minutes after the end of the fluid bolus infusion. In a multivariable model, a cardiac output response was independently associated with PbtO₂ response (adjusted odds ratio 15.4, 95% CI 1.9 to 122.0, P = 0.01) after adjusting for mean arterial pressure, intracranial pressure and end-tidal CO₂. Stroke volume variation showed a good ability to predict cardiac output response with an area under the ROC curve of 0.85 with a best cutoff value of 8%. See Figures 1 and 2.

Figure 1

Figure 2

Conclusions

Bolus fluid resuscitation resulting in augmentation of cardiac output can improve cerebral oxygenation after severe brain injury.