144 Y. El Dsouki and I. Condello: J Extra Corpor Technol 2025, 57, 137--146
Table 1. Temperature management, thresholds, and nadirs from the literature.
Category |
Details |
Authors |
Safe temperature gradient( CPB) |
Cooling gradient( blood-HCU): 10 ° C |
Engelman et al. [ 1 ] |
|
Rewarming gradient( blood-core): 4 ° C |
|
Maximum rate |
Cooling rate: 1 ° C per 3--5 min |
Wahba et al. [ 2 ] |
|
Rewarming rate: 1 ° C per 3--5 min |
|
Temperature limits |
Minimum allowable: 18 ° C( for deep hypothermic circulatory arrest) |
Saad and Aladawy [ 3 ] |
Deep hypothermia temperature protocol
Temperature-based oxygen delivery and flow adjustments
Integration of temperature, DO 2, and CO 2 management
Maximum allowable: 37 ° C( avoid hyperthermia) Cooling phase: 37 ° C? 18--22 ° C, 1 ° C every 3--5 min, Maintain blood-HCU DT 10 ° C Hypothermic maintenance: 18--22 ° C, stable, monitor NIRS Controlled rewarming: 18--22 ° C? 32 ° C, 1 ° C every 3--5 min,
Keep blood-core DT 4 ° C Final rewarming: 32 ° C? 36--37 ° C, 1 ° C every 5 min, monitor cerebral saturation( rSO 2) to prevent overheating 37 ° C( normothermic): 0 %, 286 mL / min / m 2, standard perfusion flow 32 ° C( mild hypothermia): ~ 20 %, 220 mL / min / m 2, Reduce flow ~ 10--15 % 28 ° C( moderate hypothermia): ~ 50 %, 180 mL / min / m 2, Reduce flow ~ 30 % 22 ° C( Deep Hypothermia): ~ 75 %, 120 mL / min / m 2, Reduce flow ~ 50 % 18 ° C( deep hypothermic circulatory arrest): ~ 85 %, 80 mL / min / m 2, circulatory arrest or very low flow
Engelman et al. [ 1 ]
Mukaida et al. [ 4 ]
37 ° C: Alpha-stat, high flow, normothermia, standard CO 2 removal Condello et al. [ 6 ] 32 ° C: Alpha-stat, moderate-flow, reduced VO 2, Moderate CO 2 Cavaliere et al. [ 7 ] removal 28 ° C: Alpha-stat or pH-stat, lower flow, adjusted DO 2, adjusted De Somer et al. [ 12 ]
CO 2 sweep 22 ° C: pH-stat, minimal flow to match metabolism, high CO 2 sweep to maintain pH 18 ° C: pH-stat, low-flow or arrest, max CO 2 sweep to prevent acidosis Table 2. Safe temperature gradient and threshold example for CPB.
Parameter |
Safe range |
Cooling gradient( blood-HCU) |
10 ° C |
Rewarming gradient( blood-core) |
4 ° C |
Maximum cooling rate |
1 ° C per 3--5 min |
Maximum rewarming rate |
1 ° C per 3--5 min |
Minimum allowable temperature |
18 ° C( for deep hypothermic circulatory arrest cases) |
Maximum allowable temperature |
37 ° C( avoid hyperthermia) |
Table 3. Deep hypothermia temperature threshold example.
Stage |
Target temperature |
Cooling / Warming rate |
Key considerations |
Cooling phase |
37 ° C? 18--22 ° C |
1 ° C every 3--5 min |
Maintain blood-HCU DT 10 ° C |
Hypothermic maintenance |
18--22 ° C |
Stable |
Monitor NIRS |
Controlled rewarming |
18--22 ° C? 32 ° C |
1 ° C every 3--5 min |
Keep blood-core DT 4 ° C |
Final rewarming |
32 ° C? 36--37 ° C |
1 ° C every 5 min |
Monitor cerebral saturation( rSO 2) to prevent overheating |
crucial to evaluate performance across diverse patient populations and surgical environments [ 9, 10 ]. Long-term monitoring will help assess the reliability, user interaction, and clinical outcomes associated with the system, refining the algorithm to better support individual patient needs while upholding safety standards [ 11, 12 ].