A Comparison of Cerebral Protection using Alpha-Stat and Ph-Stat Strategies in an Animal Model of Pediatric Cardiopulmonary Bypass

  • Jacob Ostrowsky, Department of Pediatric Cardiothoracic Surgery, Rainbow Babies and Children’s Hospital, Case Western Reserve University School, United States
  • Mark Henderson, Department of Pediatric Cardiothoracic Surgery, Rainbow Babies and Children’s Hospital, Case Western Reserve University School, United States
  • Ahmed Farouk, Department of Pediatric Cardiothoracic Surgery, Rainbow Babies and Children’s Hospital, Case Western Reserve University School, United States
  • Shivaprakash Seshadri, Department of Pediatric Cardiothoracic Surgery, Rainbow Babies and Children’s Hospital, Case Western Reserve University School, United States
  • Steve Schomisch, Department of Pediatric Cardiothoracic Surgery, Rainbow Babies and Children’s Hospital, Case Western Reserve University School, United States
  • Hani Hennein, Department of Pediatric Cardiothoracic Surgery, Rainbow Babies and Children’s Hospital, Case Western Reserve University School, United States

    • Objective: To compare the effects of blood-gas management using either alpha-stat (temperature-uncorrected blood-gas management) or pH-stat (temperature-corrected blood-gas management) strategies on cerebral oxygenation during cardiopulmonary bypass.

    Methods: Six piglets, ranging from 8-12 kg, were placed on cardiopulmonary bypass, and cooled to 12o C utilizing alpha-stat (N=3) or pH-stat blood gas management (N=3), then warmed to 40o C. At every 2 degrees Celsius, parameters were maintained for 10 minutes, and both arterial and venous blood gas data, pressure data, heart rate and cerebral oximetry data were recorded. Regional cerebral oximetry was monitored using near infrared reflective spectroscopy (NIRS). Continuous in-line arterial blood gases were monitored and confirmed every 10 minutes using a blood gas analyzer.

    Results: Alpha-stat animals had temperature-uncorrected arterial blood gases of; pH 7.45 ± 0.08, PaCO2 40 ± 3 mmHg, PaO2 226 ± 63 mmHg. PH-stat animals had temperature-corrected arterial blood gases of; pH 7.42 ± 0.06, PaCO2 40 ± 4 mmHg, PaO2 214 ± 54 mmHg. Both alpha-stat and pH-stat temperature management techniques demonstrated an inverse correlation to cerebral oximetry (R2=0.64, r = -0.71, P<0.0001). However, separating the two groups, the pH-stat population showed a more significant increase in cerebral oximetry, compared to Alpha-stat, across the entire hypothermic temperature range (R2=0.89, r = -0.92, P<0.0001, Fig).

    Conclusion: PH-stat blood gas management, as compared to alpha-stat, is associated with higher cerebral oxygenation during cardiopulmonary bypass. This may provide better cerebral protection, which is the goal of successful pediatric cardiac surgery in the current era.