Pancuronium does not decrease oxygen consumption during hypothermic or normothermic cardiopulmonary bypass

Area of Science:

• Anesthesiology
• Cardiovascular Surgery
• Physiology

Background:

• Hypothermic cardiopulmonary bypass can reduce systemic oxygen consumption.
• A proposed mechanism involves mitigating hypothermia-induced muscle tone (microshivering).
• Pancuronium is a neuromuscular blocking agent used for muscle relaxation.

Purpose of the Study:

• To test if pancuronium administration decreases systemic oxygen consumption during hypothermic cardiopulmonary bypass.
• To determine if this effect differs between hypothermic and normothermic bypass conditions.

Main Methods:

• Studied patients undergoing normothermic (37.6°C) and hypothermic (28.2°C) cardiopulmonary bypass.
• Measured systemic oxygen consumption using the Fick principle before and after pancuronium administration (0.15 mg/kg).
• Compared oxygen consumption changes between the two temperature groups.

Main Results:

• Oxygen consumption averaged 93 mL.min⁻¹m⁻² in normothermic and 43 mL.min⁻¹m⁻² in hypothermic groups.
• Pancuronium decreased oxygen consumption by only 2% in normothermic patients.
• Pancuronium also decreased oxygen consumption by only 2% in hypothermic patients, failing to confirm the hypothesis.

Conclusions:

• Muscle relaxation with pancuronium did not significantly reduce systemic oxygen consumption in either normothermic or hypothermic cardiopulmonary bypass.
• The hypothesis that pancuronium inhibits hypothermia-induced microshivering to reduce oxygen demand was not supported by these findings.