Respiratory Quotient and Metabolic Rate in Normal Full‐term and Small‐for‐date Newborn Infants1

Senterre, J; Karlberg, P

doi:10.1111/j.1651-2227.1970.tb17700.x

Cited by 35 publications

(22 citation statements)

References 40 publications

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“…The metabolic cost of weight gain was found to be approximately 2.3 kJ/g, which represents a significant part (i.e., 12-13%) of the overall energy expenditure. By contrast with term newborns who have low RQs (5,6,16,32), very low-birth-weight infants during the first two weeks of life exhibited RQs near unity indicating preferential carbohydrate utilisation, with an economy of lipid. …”

Section: Growth Rates It Is Generally Admitted (33 35) That Immaturementioning

confidence: 96%

Metabolic Cost of Growth in Very Low-Birth-Weight Infants

Gudinchet¹,

Schütz²,

Micheli³

et al. 1982

Pediatr Res

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Summaryied. The characteristics of each child are given in Table 1. NoneForty-eight measurements of energy expenditure were performed in 15 very low-birth-weight infants during the first 6 wk of life. Their mean birth weight and gestation age was 1223 g and 31 wk respectively. Their mean weight gain was 11.2 g/kg*d (range: -6.6 to +15.9 g/kg d.). The mean energy expenditure increased from 170 kJ/kg-d (wk 1) to 252 kJ/kg*d (wk 6). There was a significant relationship between weight gain and energy expenditure (r = 0.58, P < 0.001) and also between the net increase in body weight gain and the net increase in energy expenditure (r = 0.80, P < 0.001). From the slopes of these regression lines, the metabolic cost of growth was found to be approximately 2.3 kJ/g of weight gain. Carbohydrate oxidation represented 80% of energy expenditure at the second wk and decreased to 65% the 6th wk, whereas lipid oxidation during the same period increased from 14 to 30% and the relative protein oxidation remained unchanged, covering 5-6% of the energy expended. SpeculationThere is need for information on the metabolic cost of growth in very low-birth-weight infants because a significant proportion of energy expenditure is associated with the metabolic cost of growth due to tissue synthesis. An attempt has been made to investigate the relationship between weight gain and energy expenditure in very low-birth-weight infants. In addition, substrate oxidation was determined during the first wk of life in order to elucidate which fuel was oxidized during this period of rapid growth.Although many authors have studied the energy expenditure of very low-birth-weight infants (4,7, 11,12, 16, 23, 26,27,29,31) the energetics of growth has received little attention, particularly the partition of energy expenditure between growth and nongrowth functions (30). In healthy immature infants, high rates of weight gain are achieved and the metabolic cost of growth may represent a substantial part of the total daily energy expenditure. Such a situation is also found in children recovering from proteinenergy malnutrition (3, 34) and from burn injury (18).Recently, several energy balance studies have been performed in very low-birth-weight infants (4, 29), but there is little information on repetitive long term measurements of energy expenditure and on the metabolic cost of growth. The total energy requirement of a growing infant can be separated into two components (25): one is the energy content of tissues deposited (stored energy), the other is the extra energy expended to synthesise and deposite new tissues (metabolic cost of growth). This study is concerned with the latter and with the fuels oxidized by very lowbirth-weight infants during the first 6 wk of life.

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Section: Growth Rates It Is Generally Admitted (33 35) That Immaturementioning

confidence: 96%

Metabolic Cost of Growth in Very Low-Birth-Weight Infants

Gudinchet¹,

Schütz²,

Micheli³

et al. 1982

Pediatr Res

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“…In contrast, the SGA infant, as a result of intrauterine malnutrition, is born with decreased hepatic glycogen and adipose tissue triglyceride stores (1 [2][3][4][5][6][7][8][9][10][11][12][13][14]. These infants have lower respiratory RQ compared with the normal infants (5). In neither the IDM nor SGA infants have the quantitative contribution of fat to oxidative metabolism or Received June 14, 199 1; accepted August I , 199 1. the &antitative measurement of lipolysis been done.…”

mentioning

confidence: 99%

“…During the immediate postnatal period, there is a rapid decrease in plasma glucose concentration along with an increase in FFA and glycerol (1)(2)(3). The latter, representing an initiation of lipolysis in the adipose tissue, is associated with a shift in fuel source for energy from predominantly carbohydrates in utero to a carbohydrate and fat fuel mix in the extrauterine life (4,5). Such a shift is also evidenced by the change in RQ, which declines to approximately 0.8 by 2 h of age, suggesting a significant contribution of fat to the oxidative metabolism (5)(6)(7).…”

mentioning

confidence: 99%

“…It has been hypothesized that the discrepancy between the plasma concentration of FFA and glycerol in the IDM may be related to increased reesterification of fatty acids in the adipocytes (3). In contrast, the SGA infant, as a result of intrauterine malnutrition, is born with decreased hepatic glycogen and adipose tissue triglyceride stores (1 [2][3][4][5][6][7][8][9][10][11][12][13][14]. These infants have lower respiratory RQ compared with the normal infants (5).…”

mentioning

confidence: 99%

“…The latter, representing an initiation of lipolysis in the adipose tissue, is associated with a shift in fuel source for energy from predominantly carbohydrates in utero to a carbohydrate and fat fuel mix in the extrauterine life (4,5). Such a shift is also evidenced by the change in RQ, which declines to approximately 0.8 by 2 h of age, suggesting a significant contribution of fat to the oxidative metabolism (5)(6)(7). Within the adipose tissue, during lipolysis, triglycerides are hydrolyzed, resulting in release of FFA and glycerol.…”

mentioning

confidence: 99%

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Glycerol Metabolism and Triglyceride-Fatty Acid Cycling in the Human Newborn: Effect of Maternal Diabetes and Intrauterine Growth Retardation

Patel

Kalhan

1992

Pediatr Res

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ABSTRACT. Kinetics of glycerol metabolism and triglyceridelfatty acid cycling were quantified in 12 healthy, normal, appropriate-for-gestational-age (AGA) infants, eight small-for-gestational-age (SGA) infants, and five infants of insulin-dependent diabetic mothers (IDM) at less than 48 h of age. Stable isotope-labeled [2-13C]glycerol and [6,6-ZHz]glucose in combination with indirect respiratory calorimetry were used. The tracers were used as constant rate infusion and steady state isotopic enrichment of glucose, glycerol, and bicarbonate was measured by mass spectrometric methods. After a 7-to 9-h fast, the plasma glucose, glycerol, and FFA concentrations were similar in the AGA and IDM groups. In the SGA group, the plasma glucose concentration was significantly lower than that in the AGA group throughout the study, but plasma FFA and glycerol concentrations were not different from those in the AGA infants. Plasma betahydroxybutyrate concentration was significantly elevated in the AGA group compared with IDM and SGA infants (AGA 0.59 -1-0.39, SGA 0.35 + 0.09, IDM 0.33 + 0.21 mmol/L; mean f SD). The rate of appearance of glycerol was significantly elevated (p < 0.05) in SGA infants (AGA 9.47 + 2.11, IDM 9.55 + 2.14, SGA 12.15 + 3.87 pmol/kg.min). Between 80 and 90% of glycerol turnover was converted to glucose, accounting for 20% of glucose turnover with no significant difference in the three groups. Approximately 35% of glycerol carbon was recovered in the bicarbonate (COz) pool. Less than 5% of C 0 2 carbon was derived from glycerol. Estimation of triglyceride-fatty acid cycle revealed that the triglyceride energy mobilized was increased in SGA infants. Only 22-24% of the triglyceride energy released was oxidized to COz in the newborn infants; the majority (76-78%) was recycled back to the adipose tissue. These data show that lipolysis is active in the immediate neonatal period. The contribution of fat to oxidative metabolism is increased in SGA infants. The major metabolic fate of glycerol in the neonate is conversion to glucose, and glycerol is a minor contributor to oxidative metabolism. (Pediatr Res 31: [52][53][54][55][56][57][58] 1992)

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Lipid Metabolism in the Fetal-Placental Unit

Kammerer¹

1998

Principles of Perinatal—Neonatal Metabolism

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Respiratory Quotient and Metabolic Rate in Normal Full‐term and Small‐for‐date Newborn Infants1

Abstract: Key words: Respiratory quotient, metabolic rate, fullterm newborn infants, small-for-date newborn infants Acta Plediat Scand 59

Cited by 35 publications

References 40 publications

Metabolic Cost of Growth in Very Low-Birth-Weight Infants

Metabolic Cost of Growth in Very Low-Birth-Weight Infants

Glycerol Metabolism and Triglyceride-Fatty Acid Cycling in the Human Newborn: Effect of Maternal Diabetes and Intrauterine Growth Retardation

Lipid Metabolism in the Fetal-Placental Unit

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