Respiratory quotient changes in full term newborn infants within 30 hours from birth before start of milk feeding

Abstract

Objective: To evaluate substrate utilization in full-term newborn infants, fed every 3±4 h with glucose 10% solution, within 30 h from birth. Design: Random. Setting: Full term newborn infants at the Paediatric Division City Major Hospital, Chair of Paediatrics, Verona University. Subjects: Forty-six newborn infants, 24 females and 22 males of 39 AE 2 weeks gestational age. Methods: Oxygen consumption (VO 2 ) and CO 2 production (VCO 2 ) were measured. Permitting the computation of the respiratory quotient (RQ), which expresses substrate oxidation, at 6 and 30 h from birth. An indirect calorimeter (Deltratrac TMII-MBM-200-DATEX) was used to measure components of energy-balance. Results: Energy expenditure calculated at 6 h was 8.130 (AE1.5757) kJakgah. At 30 h the value changed to 8.858 (AE1.483) kJakgah. Statistical evaluation (t-student) showed a signi®cant (P 0.000) variation in RQ values (6 h: RQ 0.94; 30 h: RQ 0.88). Conclusions: Respiratory quotient suggests an increase of energy derived from fat metabolism at 30 h from birth. Our data con®rm that early breast feeding or formula milk feeding could represent a physiological approach to nutritional regimen of the newborn infant.

The Application of an Automated Oxygen Concentration Control and Measurement System to a Miniaturized Energy Consumption Measurement System Using Resistive-Type Oxygen Gas Sensors

“…A reduction in the RQ value indicates a decreasing rate of carbohydrate metabolism and a shift towards alternative substrates such as proteins and particularly, fats. Previous studies have suggested that the quantity of proteins deposited is closely related to the protein intake, while the quantity of fat deposited is closely related to the energy intake [3]. Therefore, the RQ value provides a valuable indicator of a premature infant's energy intake.…”

“…Meanwhile , the generated carbon dioxide volume during the same period is approximately 6.305 ± 1.259 (ml/kg/min). Furthermore, newborn infants within 30 hours from birth and prior to the start of milk feed-in consume an oxygen volume of approximately 7.422 ± 1.241 (ml/kg/min), and generate a carbon dioxide volume of approximately 6.532± 1.091 (mUkg/min) [3]. Finally, it has been reported that the respiratory rate of newborn infants is approximately 40-60 breaths/min [3,12].…”

A calibration system of O2 consumption and CO2 production for premature infants

“…An important metabolic indicator called the respiratory quotient ͑RQ͒ is used to represent the oxidized substrate. 15 RQ is determined by the ratio of V CO 2 to V O 2 , and the theoretical respiratory quotient of ethanol combustion is obtained as…”