Respiratory water loss in fullterm infants on their first day after birth

Measurements of water loss from the airways, oxygen consumption and carbon dioxide production were made in 12 fullterm, newborn infants on their first day after birth, using an open flow-through system. The system includes a mass spectrometer, specially equipped with a water channel, for analysis of gas concentrations. To avoid condensation of water vapour, the tubing in the flow-through system is heated. Respiratory water loss was 4.9 +/- 1.2 (SD) mg/kg min, which meant an insensible water loss from the respiratory tract of 25.4 +/- 6.9 (SD) g per infant and 24 h at rest, at an ambient temperature of 32.2 degrees C and with an ambient humidity of 50%. Oxygen consumption was 6.0 +/- 0.8 (SD) ml/kg min. An inverse relationship was found between respiratory water loss and ambient humidity, with higher losses at a low than at a high humidity. Oxygen consumption did not change very much with ambient humidity.     

Respiratory water loss in relation to activity in fullterm infants on their first day after birth

Respiratory water loss (RWL), oxygen consumption and carbon dioxide production were measured in ten fullterm infants on their first day after birth, using an open flow-through system with a mass spectrometer, specially equipped with a water channel, for analysis of gas concentrations. Measurements were made both with the infant asleep and during different levels of motor activity. The ambient temperature was maintained at approximately 32.5 degrees C and the ambient relative humidity at 50%. RWL increased from 4.2 +/- 0.7 (SD) mg/kg min when the infant was asleep to 6.3 +/- 1.0 mg/kg min when he or she was awake but calm; with increasing activity there was a further increase in RWL. The oxygen consumption increased from 5.4 +/- 0.9 (SD) ml/kg min during sleep to 6.9 +/- 0.8 (SD) ml/kg min when awake, and also increased further with increasing activity.     

Respiratory water loss in relation to gestational age in infants on their first day after birth

Respiratory water loss, oxygen consumption and carbon dioxide production were measured in 32 infants on their first day after birth. Gestational age was between 27 and 41 weeks. All infants were studied in incubators with 50% ambient relative humidity and an ambient temperature that allowed the infant to maintain a normal and stable body temperature. During the measurements the infants were usually asleep. Respiratory water loss was found to be highest in the most preterm infants and lower in more mature infants. Respiratory water loss per breath (mg/kg) was almost the same at all gestational ages and the higher respiratory water loss found in the most preterm as compared with the more mature infants is thus due to a higher rate of breathing. Oxygen consumption was lowest in the most preterm infants and increased with increasing gestational age. Thus, in full-term infants respiratory water loss and transepidermal water loss are of approximately equal magnitude at an ambient humidity of 50%, while respiratory water loss constitutes a smaller proportion than trans-epidermal water loss in very preterm infants. Respiratory water loss increases with the rate of breathing. ? Insensible water loss, oxygen consumption, preterm infants, respiratory water loss G Sedin, Department of Paediatrics, University Hospital, S-751 85 Uppsala, Sweden     

Transepidermal water loss in newborn infants. IX. The relationship between skin blood flow and evaporation rate in fullterm infants nursed in a warm environment

In order to investigate whether a change in skin blood flow is associated with changes in the evaporative loss of water from the skin of fullterm appropriate for gestational age infants, we measured the evaporation rate and skin blood flow in the body temperature range 36.6 to 37.2 degrees C. Fifteen healthy, fullterm newborn infants delivered by Caesarean section were studied in a warm environment. Evaporation rate and skin blood flow were measured non-invasively without disturbing the infant. When the body temperature slowly rose because of the warm environment, the skin blood flow steadily increased. The rate of evaporation of water from the skin slowly decreased until a body temperature of 37.1 degrees C was reached. The evaporation rate then suddenly increased as the infant began to sweat. Thus, in fullterm newborn infants born by Caesarean section the skin blood flow increases in the body temperature range 36.6-37.1 degrees C but does not influence the evaporation rate from the skin.     

Respiratory water loss and oxygen consumption in full-term infants exposed to cold air on the first day after birth

Respiratory water loss, oxygen consumption, carbon dioxide production and skin blood flow were measured continuously in nine full-term infants on the first day after birth. After at least 18 min of measurements with the infant asleep in an incubator, with an air temperature of 33°C and a relative humidity of 50%, the temperature of the incubator air was lowered to less than 27.5°C. This resulted in a significant decrease in skin temperature and peripheral skin blood flow, while the infant's core temperature remained unchanged. At the same time, mean respiratory water loss increased from 3.7 to 6.1 mg/kg-min, which can be explained partially by the decrease in ambient humidity that accompanied the decrease in air temperature. In addition, mean oxygen consumption increased from 5.3 to 7.9 ml/kg. min and mean carbon dioxide production increased from 3.8 to 5.9 ml/kg-min. There was no concomitant increase in motor activity. Thus, when the newborn infants were exposed to cool air, they reacted with an increase in respiratory water loss, oxygen consumption and carbon dioxide production before their core temperature was affected and without increasing their motor activity.     

The early social environment of premature and fullterm infants

The behaviors of 10 mothers of prematures and 29 mothers of fullterms were compared from 7-h observations made in the home when the infants were 2, 3, 4 and 5 weeks post-term. The observation day was divided into four mutually exclusive interactional contexts that together made up the total day: feeding time, changing or bathing time, time when the mother and infant were in physical contact but the mother was not caretaking, and time the infant was alone. Measures of ten maternal behaviors were also compared: moving, rocking, patting, caressing, talking, looking, engaging in vis-a-vis with the baby, holding or carrying, smiling or laughing, and stimulating the baby to suck. Mothers of prematures left their infants alone more and changed them less than mothers of fullterms. In addition, mothers of prematures moved their infants less often, talked to their infants less, looked at their infants less, and held their infants less. These results indicate that, over the 7-h day, prematures receive markedly less stimulation than fullterms. Since the neurobehavioral characteristics of premature and fullterm infants are known to differ, it is suggested that these differences in maternal behaviors may be in response to infant cues and appropriate for the infants.     

The effect of birth asphyxia on plasma free amino acids in preterm newborn infants

The postnatal plasma amino acid pattern was compared in 16 asphyxiated and 13 non-asphyxiated preterm newborn infants. The lactic acidosis induced by asphyxia was associated with a marked rise in the total amino acid content of the plasma. Among the 17 individual amino acids determined the concentrations of alanine, proline, taurine, glutamate, valine, methionine and lysine were significantly elevated. The accumulation of alanine was particulary marked and its concentration showed a significant linear correlation with that of lactate (p less 0.001). A similar relationship was observed between other potentially glucogenic amino acids and lactate. It is suggested that an impaired gluconeogenesis may be responsible for the accumulation of glucogenic amino acids. The response of the plasma aminogram to asphyxia resembles that associated with hypoglycaemia in the small-for-gestational-age infant, where a delay in the maturation of key gluconeogenic enzymes seems to account for the reduced hepatic disposal of glucose precursors.     

Indomethacin therapy on the first day of life in infants with very low birth weight

To investigate the optimal timing for treatment of small premature infants, we performed a double-blind, controlled trial of indomethacin therapy on the first day of life in 104 infants weighing between 700 and 1300 gm. Infants were given indomethacin or placebo at a mean age of 15 hours. Eleven of the 56 infants given placebo developed large left-to-right shunts through a patent ductus arteriosus. In contrast, only two of the 51 infants given indomethacin developed large shunts (P less than 0.025). There were no significant differences in incidence of surgical ligation, duration of oxygen therapy, duration of endotracheal intubation, days required to regain birth weight, or incidence of complications. However, the power of the tests of significance was low because of the small number of patients. Thus, although the incidence of large left-to-right ductus shunts was decreased in the indomethacin group, morbidity was not otherwise altered for the entire group of patients, possibly because of the relatively low incidence (21%) of large shunts in the placebo group. We conclude that although treatment with indomethacin on the first day of life appears to be safe, there is little advantage to its use in centers where the incidence of large shunts through a patent ductus arteriosus is relatively low.     

Respiratory water loss and oxygen consumption in newborn infants during phototherapy

Respiratory water loss was measured together with oxygen consumption (VO2) and carbon dioxide production (VCO2) in 11 full-term and eight preterm infants (mean gestational age 34 weeks, range 31-36 weeks) before and during 1 h of phototherapy. The method for determination of respiratory water loss, VO2 and VCO2 was based on an open flow-through system with a mass spectrometer for measurement of gas concentrations. All infants were studied naked in an incubator with an ambient relative humidity of 50% and with a controlled environment with respect to temperature and air velocity. The infants were calm during the measurements. Before phototherapy, in term infants respiratory water loss was 4.4 (SD 0.7) mg/kg min and VO2 5.9 (0.9) ml/kg min and in preterm infants respiratory water loss was 4.7 (0.8) mg/kg min and VO2 6.1 (0.8) ml/kg min. No significant difference was found between values obtained during or after 1 h of phototherapy and those obtained before.     

Free and sulfoconjugated plasma catecholamines in premature infants and mature newborn infants after birth

Sulfate conjugation represents a major pathway for the inactivation of free catecholamines. We investigated the ability of newborns to protect the body against an overflow of free catecholamines by sulfoconjugation. No difference of free catecholamines in the umbilical artery was found in preterm and term newborns. Furthermore, preterm and term newborns were able to form sulfoconjugated catecholamines. In term newborns, but not in preterm newborns, there was a significant relationship between free catecholamines and their respective sulfoconjugated forms (p less than 0.001). In comparison to term infants sulfoconjugated dopamine and norepinephrine were significantly decreased in preterm newborns, although the placental extraction rates of these catecholamines were markedly lower in preterm infants. This favors the conclusion, that synthesis rather than increased degradation may be responsible for the low levels of sulfoconjugated catecholamines in preterm infants. Thus, preterm newborns might be less able to inactivate free catecholamines by sulfoconjugation. The clinical importance of these results concerning treatment of preterm newborns with dopamine and noradrenaline has yet to be established.     

Evaporation rate and skin blood flow in full term infants nursed in a warm environment before and after feeding cold water

Earlier results have shown that some infants born by elective Caesarean section start to sweat in a warm environment while others do not, and that sweating can be inhibited by feeding cold glucose. To determine whether these earlier observations, indicating a difference in postnatal temperature adaptation, could be reproduced in vaginally born infants, we measured the rate of evaporation from the skin surface, body and skin temperatures from several sites, skin blood flow and respiratory rate in newborn infants nursed in a warm environment, before and after feeding cold water. In all infants the body and skin temperatures increased in the warm environment (p < 0. 01), with a decreasing difference between oesophageal and leg skin temperature (p < 0. 01). Visible sweating occurred in 9/14 infants at a rectal temperature of 37.5°C. In the infants who started to sweat, evaporation rate increased from 5.6 ± 2. 8 (SD) g/m²/h 15min before sweating to 15.7 ± 10.6 g/m²/h (p < 0.05) when sweat became visible and the infants were fed cold water. After feeding of cold water the evaporation rate decreased and within 10min returned to a value not significantly different from the pre-sweating value. Interscapular skin blood flow had increased by 42% (p < 0. 01) at the time of sweating and decreased by 22% (p < 0. 01) after feeding cold water. In the infants who did not start to sweat, no increase in evaporation rate was noted and the changes in skin blood flow were not statistically significant. The infants who started to sweat did not differ from those who did not regarding maternal medication during delivery. We conclude that some, but not all, newborn infants start to sweat at a body temperature of 37.5°C. In the infants who start to sweat, sweating and an increase in skin blood flow can be inhibited by feeding cold water. There seem to be individual differences in the regulation of body temperature in newborn infants, possibly due to a delayed change in the central temperature set-point in some infants.     

Transepidermal water loss in preterm and newborn infants (author's transl)

69 measurements of water loss from the skin were made on 57 preterm and newborn babies (gestational age 31-40 weeks; body weight 900 g-350 g) in their first week of life using the Evaporimeter-method. All measurements were made at 18 different skin sites of the naked baby in a standard single-walled incubator. A graphic method described the correlation between transepidermal water loss and body weight. The mean value of water loss in babies weighing greater than 1850 g was 6,6 g/m2h (10,2 ml/kg 24h) and increased up to threefold values when body weights were smaller. A similar course was found during phototherapy: average values of 8 g/m2h (12,7 ml/kg 24 h) were measured in babies weighing greater than 1900 g increasing markedly in lower birth weights. Some single observations are reported.