A simple solution is "prime" for fetal cardiopulmonary bypass

Area of Science:

• Perinatal medicine
• Cardiovascular physiology
• Fetal surgery

Background:

• Placental dysfunction and impaired fetal gas exchange are common after fetal bypass.
• The optimal composition of prime solutions for fetal bypass remains undefined.
• Calcium and sodium bicarbonate are often added to adjust physiological values in prime solutions.

Purpose of the Study:

• To investigate the effects of calcium chloride and sodium bicarbonate additions to fetal bypass prime solutions.
• To determine if these common adjustments are warranted in fetal bypass procedures.
• To assess the impact on fetal hemodynamics and gas exchange.

Main Methods:

• Ovine fetuses (104-110 days' gestation) underwent a 30-minute fetal bypass.
• Calcium chloride and sodium bicarbonate were added to prime solutions to adjust ionized calcium and pH.
• Fetal hemodynamics and arterial blood gases were monitored before and during bypass.

Main Results:

• Calcium addition correlated with decreased fetal pH and pO2, and increased pCO2.
• Bicarbonate addition correlated with altered pCO2 and pO2, and reduced umbilical blood flow.
• Both calcium and bicarbonate negatively impacted fetal gas exchange and hemodynamics.

Conclusions:

• Calcium addition to the prime solution adversely affects fetal gas exchange, worsening acidosis during fetal bypass.
• Bicarbonate addition is also detrimental, leading to increased CO2 production and impaired hemodynamics.
• These findings suggest reconsidering the routine use of calcium and bicarbonate in fetal bypass prime solutions.