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Evaluation of delivery systems for oxygenated cardioplegia
1Department of Surgery, Dalhousie University, Halifax, NS.
Insights
Oxygen delivery to the heart during surgery was compared across four systems. While blood cardioplegia offers the highest oxygen capacity, a bubbler system allows for flexible cold cardioplegia delivery, outperforming membrane and blood systems.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Cardioplegia Delivery Systems
Background:
- Effective myocardial protection during cardiac surgery is crucial.
- Cardioplegia solutions deliver oxygen and nutrients to the heart.
- Various delivery systems exist, each with potential advantages and limitations.
Purpose of the Study:
- To evaluate and compare the oxygen-carrying capacity of different cardioplegia delivery systems.
- To assess the feasibility of delivering cold cardioplegia at various times during cardiac procedures.
Main Methods:
- Four cardioplegia delivery systems were analyzed: nonoxygenated crystalloid, oxygenated crystalloid (bubbler and membrane), and blood cardioplegia (Shiley-Buckberg).
- Oxygen-carrying capacity (ml O2/dl) was measured for each system.
- The ability to deliver cold cardioplegia independently of heat exchangers was assessed.
Main Results:
- Oxygen delivery ranged from 0.56 ml/dl (nonoxygenated crystalloid) to 4.2 ml/dl (blood cardioplegia, adjusted for hypothermia).
- Oxygenated crystalloid systems delivered 3.2 ml/dl (bubbler) and 3.7 ml/dl (membrane).
- The bubbler system uniquely allowed cold cardioplegia administration at any surgical stage, unlike membrane and blood systems reliant on heat exchangers.
Conclusions:
- Blood and oxygenated crystalloid cardioplegia show comparable oxygen provision to the myocardium during ischemic arrest.
- The bubbler oxygenating system offers superior flexibility for cold cardioplegia delivery compared to membrane and blood systems.
- System choice may depend on balancing oxygen delivery needs with the requirement for intraoperative temperature control.
Abstract:
The oxygen-carrying capacity of four delivery systems for blood and crystalloid cardioplegia was evaluated: nonoxygenated crystalloid cardioplegia, crystalloid cardioplegia oxygenated with a bubbler system and with a membrane system and, finally, blood cardioplegia delivered by the Shiley-Buckberg system. The nonoxygenated crystalloid cardioplegic solution delivered 0.56 ml of oxygen/dl of solution, the bubbler oxygenating system delivered 3.2 ml/dl and the membrane oxygenating system made available 3.7 ml/dl. Blood cardioplegia delivered 4.2 ml/dl when oxygen-carrying capacity was corrected for the shift in the oxyhemoglobin dissociation curve that occurs with hypothermia. There appears to be no advantage between blood and oxygenated crystalloid cardioplegia with respect to the ability of these solutions to provide oxygen to the myocardium during ischemic arrest. However, the bubbler oxygenating system is superior to the membrane and blood delivery systems in that it could administer cold cardioplegia at any time during the operation. In contrast, the membrane and blood cardioplegia delivery systems both depend on integral heat exchangers which limit the delivery of cold cardioplegia to the period of hypothermia.