Rewarming: comparison of contemporary heat-exchangers

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Thermoregulation

Background:

• Efficient heat exchange is crucial during cardiopulmonary bypass to minimize patient pump time.
• Comparative studies on the in vivo function of commonly used heat exchangers are limited.
• Existing heat exchangers include Sarns, Cobe, and Medtronics Maxima models.

Purpose of the Study:

• To compare the in vivo performance of commercially available heat exchangers (Sarns, Cobe, Medtronics Maxima) and an experimental Haemonetics model.
• To evaluate the efficiency of different heat exchangers in rewarming patients during cardiopulmonary bypass.

Main Methods:

• Thirty-two pigs (63-74 kg) underwent cardiopulmonary bypass with extensive thermocouple placement for temperature monitoring.
• Animals were cooled to a bladder temperature of 14°C, maintained for 10 minutes, and then rewarmed to 37°C.
• Pump flow was maintained at 50-60 ml/kg/min with standard ventilation; rewarming times were compared across heat exchangers.

Main Results:

• The Haemonetics heat exchanger demonstrated a significantly shorter rewarming time (68.7 ± 13.4 min) compared to Cobe (82.0 ± 12.0 min), Sarns (80.3 ± 15.4 min), and Maxima (89.0 ± 13.9 min) (p < 0.05).
• The performance advantage of the Haemonetics model was most pronounced at lower temperatures.
• No statistically significant differences in rewarming efficiency were observed at higher temperatures among the tested devices.

Conclusions:

• The experimental Haemonetics heat exchanger offers superior rewarming efficiency compared to current market options, particularly at lower temperatures.
• While current heat exchangers are comparable, technological advancements can lead to improved performance.
• Further investigation into advanced heat exchanger designs is warranted to optimize patient outcomes during cardiopulmonary bypass.