pH-stat ventilation management: a simple method of achieving this regimen

Since the advent of extracorporeal circulation for life support during cardiac surgery, there have been varied opinions as to the best method of ventilating an oxygenator to achieve the optimum arterial blood gas. With respect to the optimum pCO2, clinical investigators have focused primarily on the pros and cons of the alpha-stat and pH-stat ventilation schemes. pH-stat is a ventilation scheme that attempts to maintain the temperature corrected pH of the arterial blood at 7.40, no matter what the actual temperature of the blood. This paper does not attempt to elucidate the benefits of one scheme over the other, but is offered to provide perfusionists with a simple method of achieving pH-stat ventilation, using a CO2 source and materials readily available in any operating room. Strict adherence to a few cautionary notes should enable any perfusionist to safely deliver pH-stat ventilation when indicated. This technique of providing pH-stat ventilation has been used at our institution for over three years. It has proven to be easy to accomplish, adjust and maintain.