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Energy expenditure and fluid and electrolyte requirements in anesthetized infants and children
1Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905.
Insights
Indirect calorimetry revealed significantly lower energy expenditure in children under halothane anesthesia, impacting fluid and electrolyte needs. These findings suggest current standards for pediatric anesthesia may overestimate requirements.
Area of Science:
- Pediatric Anesthesiology
- Clinical Nutrition
- Metabolic Studies
Background:
- Accurate calculation of energy, fluid, and electrolyte needs is critical for pediatric patients undergoing anesthesia.
- Previous standards for these requirements may not be applicable during specific anesthetic states like halothane anesthesia.
Purpose of the Study:
- To determine energy expenditure, fluid volume, and electrolyte requirements in infants and children during halothane anesthesia.
- To compare these calculated needs with existing standards and assess the appropriateness of extrapolating awake values.
Main Methods:
- Indirect calorimetry was employed in 31 pediatric patients (3.8-25 kg) undergoing minor surgery with spontaneous breathing under halothane anesthesia.
- A nonrebreathing anesthesia circuit, mass spectrometry for gas analysis, pneumotachography, and in-line capnography were utilized.
- Regression equations were derived to relate energy expenditure (E), fluid volume (FV), and weight (kg).
Main Results:
- Energy expenditure (E) followed the equation E = 1.5 x kg + 5.2 (r=0.96).
- Fluid volume (FV) followed the equation FV = 2.4 x kg + 8.6 (r=0.96).
- Energy expenditure and electrolyte requirements (sodium, potassium) were up to 50% lower than previously reported values.
Conclusions:
- Energy expenditure during halothane anesthesia in children is substantially lower than previously reported, making extrapolation from awake values inappropriate.
- Consequently, fluid and electrolyte requirements (sodium, potassium) are also reduced during halothane anesthesia compared to established standards.
- This study highlights the need for revised nutritional support guidelines for pediatric patients under halothane anesthesia.
Abstract:
In 31 infants and children (body weights ranging from 3.8 to 25 kg), indirect calorimetry was used for the calculation of energy needs (E, kcal/h), fluid volume (FV, ml/h) and electrolyte requirements (sodium, Na+, and potassium, K+, mmol/liter per hour) during halothane anesthesia. The children were spontaneously breathing and undergoing minor lower abdominal or orthopedic surgery. A nonrebreathing anesthesia circuit was used, and gas concentrations were measured by a mass spectrometer. For the evaluation of ventilation during periods of measurements, pneumotachography and in-line capnography were used. Energy expenditure was related to weight and followed the regression equation E = 1.5 X kg + 5.2; r = 0.96. The energy needs were converted to fluid volumes according to the water requirements for heat production, which resulted in the following relationship between FV and weight: FV = 2.4 X kg + 8.6; r = 0.96. The energy expenditure was up to 50% lower than in previous reports. Extrapolations of energy needs from awake values are inappropriate to use during halothane anesthesia. Because of the low energy expenditure during anesthesia, requirements of sodium and potassium were up to 50% lower than those based on previous standards.