Acid-base control during hypothermia. Acid-base control in children during hypothermia without temperature correction...

Area of Science:

• Pediatric Cardiac Surgery
• Anesthesia
• Cardiopulmonary Bypass
• Hypothermia Management

Background:

• Maintaining acid-base balance during cardiopulmonary bypass with deep hypothermia is critical for pediatric open-heart surgery.
• Previous methods involving higher CO2 concentrations have been used.
• The optimal pH strategy during hypothermic bypass remains an area of investigation.

Purpose of the Study:

• To evaluate the efficacy and safety of maintaining a temperature-uncorrected pH of 7.4 during deep hypothermic cardiopulmonary bypass in pediatric patients.
• To assess the impact of varying CO2 concentrations on acid-base status and clinical outcomes.

Main Methods:

• Twenty-eight children undergoing open-heart surgery with deep hypothermia were studied.
• pH was maintained at 7.4 (uncorrected for temperature) by adjusting inspired CO2 to achieve a target PaCO2 of 5.33 kPa (uncorrected).
• Inspired CO2 concentrations of 1-2% were used, with 5% CO2 being a previously used higher concentration.

Main Results:

• Satisfactory results were achieved with 1-2% CO2.
• No adverse clinical side effects were observed.
• Acid-base status remained stable for 24 hours in 16 out of 28 patients.

Conclusions:

• Maintaining a temperature-uncorrected pH of 7.4 during hypothermic cardiopulmonary bypass is theoretically supported.
• Clinical observations suggest this strategy may improve myocardial function and systemic/cerebral perfusion in pediatric patients.
• Low CO2 concentrations (1-2%) appear effective and safe for achieving this pH target.