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Updated: Jul 19, 2026
Establishment of Deep Hypothermic Circulatory Arrest in Rats
Published on: December 16, 2022
Biologically variable bypass reduces enzymuria after deep hypothermic circulatory arrest.
Rohit K Singal1, Leanne M Docking, Linda G Girling
1Department of Surgery, University of Manitoba, Winnipeg, Manitoba, Canada.
This study compared two types of heart-lung machine perfusion in pigs undergoing a procedure called deep hypothermic circulatory arrest. One group received standard nonpulsatile perfusion, while the other received biologically variable perfusion, which mimics natural heart rhythms. The researchers looked at urine output and markers of kidney damage. They found that biologically variable perfusion led to better urine output and lower levels of kidney injury markers. The pigs also cooled and warmed up faster with this method. The authors suggest that using biologically variable perfusion could help reduce kidney damage during heart surgery.
Area of Science:
- Cardiovascular surgery outcomes research within perioperative medicine
- Renal physiology in critical care
- Biomedical engineering in surgical perfusion
Background:
Renal injury is a known complication of open-heart surgery. Cardiopulmonary bypass has been linked to this risk. Prior research has shown that deep hypothermic circulatory arrest can lead to tubular damage. However, the role of perfusion strategy in mitigating this injury remains unclear. No prior work had resolved how perfusion variability might affect renal function. This gap motivated investigation into whether biologically variable perfusion could reduce renal injury. Established knowledge includes the role of enzymuria as a marker of tubular damage. This paper's contribution is to test a novel perfusion approach in a porcine model. The study aims to clarify whether physiological flow variability can improve outcomes.
Purpose Of The Study:
The study aimed to compare conventional nonpulsatile perfusion with biologically variable perfusion in a porcine model of deep hypothermic circulatory arrest. The specific problem addressed is whether physiological flow variability can reduce renal injury. The motivation stems from the high incidence of postoperative renal complications. The hypothesis was that biologically variable perfusion would decrease enzymuria. The study design included three groups: BVP, NP, and sham. The primary outcome was enzymuria levels. The secondary outcomes included cooling and rewarming times. The study sought to determine if BVP could improve renal function.
Main Methods:
The study used a randomized controlled design with pigs assigned to biologically variable perfusion or nonpulsatile perfusion. Animals were cooled to 18 degrees Celsius, arrested for one hour, then reperfused and rewarmed. Sham-treated pigs served as controls. Hemodynamics and urine output were monitored. Urinary enzyme levels were measured for gamma glutamyl transpeptidase, alkaline phosphatase, and glutathione S-transferase. Urine proteomics were analyzed using mass spectrometry. Cooling and rewarming times were recorded. Data were compared between groups using statistical analysis. Post-hoc comparisons were performed for enzymuria markers.
Main Results:
Urine output after arrest was significantly higher with biologically variable perfusion compared to nonpulsatile perfusion. Enzymuria levels were elevated in the nonpulsatile group but not in the biologically variable group. Proteomic analysis showed abnormal proteins in nonpulsatile perfusion. Cooling time was shorter with biologically variable perfusion. Rewarming time was also reduced in the biologically variable group. Urinary enzyme markers were consistently lower in the biologically variable group. Sham-treated pigs showed no enzymuria elevations. The results suggest biologically variable perfusion may reduce renal injury.
Conclusions:
The authors proposed that biologically variable perfusion may decrease enzymuria after deep hypothermic circulatory arrest. The findings suggest that physiological flow variability could improve renal function. The study traced this claim to the observed differences in enzymuria and proteomic profiles. The authors did not claim that biologically variable perfusion is essential for all cases. They suggested that this strategy could shorten bypass duration. The results were specific to the porcine model used. No generalizations beyond the study's scope were made. The authors emphasized the need for further investigation in clinical settings.
Frequently Asked Questions
The authors propose that physiological flow variability may reduce renal tubular injury by improving perfusion dynamics during cooling and rewarming.
Mass spectrometry was used to analyze urine proteomics and identify abnormal proteins associated with renal injury.
The study used pigs to simulate deep hypothermic circulatory arrest and assess renal function in a controlled experimental setting.
Sham-treated pigs served as controls to confirm that enzymuria was related to bypass and arrest rather than surgical stress alone.
Enzymuria was measured using urinary levels of gamma glutamyl transpeptidase, alkaline phosphatase, and glutathione S-transferase.
The authors suggest that biologically variable perfusion may decrease renal injury and potentially shorten bypass duration in clinical settings.
