Comparison between Bubble CPAP and Ventilator-derived CPAP in Rabbits

Background

Continuous positive airway pressure (CPAP) is used in infants with respiratory distress and apnea. Bubble CPAP (B-CPAP) and ventilator-derived CPAP (V-CPAP) are two of the most popular CPAP modes, and use different pressure sources. However, few studies have been performed to compare their differences and effectiveness. This study was to determine whether B-CPAP and V-CPAP would have different effects on vital signs and arterial blood gas analysis.

Methods

We performed a randomized crossover study to measure vital signs, including mean blood pressure (MBP), heart rate (HR), and respiratory rate (RR), in 12 ketamine-anesthetized healthy rabbits receiving endotracheal intubation by tracheostomy with B-CPAP or V-CPAP. Arterial blood was also sampled and analyzed for PaO₂, PaCO₂, HCO₃⁻ and pH.

Results

We observed statistically significant decreases in RR, pH and PaO₂ with corresponding incrases in PaCO₂ and HCO₃⁻ during the V-CPAP; however, no significant changes from baseline were observed for B-CPAP. Neither modality resulted in statistically significant changes in MBP or HR. Both forms of CPAP altered vital signs and arterial blood gases in a similar manner. There was a trend towards a lower percentage of change from baseline in all variables in B-CPAP compared with V-CPAP.

Conclusions

Our results suggest that B-CPAP seems to be superior to V-CPAP in terms of its effect on arterial blood gases and vital signs. We speculate that B-CPAP could have certain protective effects that better preserve both arterial blood gases and vital signs when compared to V-CPAP. However, the results of this study still need to be tested by clinical study.

Key Words:  blood gas analysis , blood pressure , continuous positive airway pressure (CPAP) , heart rate , rabbits

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