Gunnar Sedin

TRANSEPIDERMAL WATER LOSS IN NEWBORN INFANTS

ABSTRACT. The amount of water evaporated from the skin of newborn infants and the temperatures of the skin, of the ambient air, and of the surfaces facing the infants were measured and used as a basis for calculation of the evaporative, radiative and convective heat exchange between the infant and the environment. The infants were of varying gestational ages, from 25 to 39 completed weeks of gestation. Evaporative heat exchange was high in the most preterm infants when nursed at a low ambient humidity, while the high ambient humidity needed to maintain these infants at a stable body temperature led to a low loss of heat through radiation and convection or even a heat gain. In the more mature infants evaporative heat exchange was lower, while radiative and convective heat exchange was higher.

Preterm birth contributes to increased vascular resistance and higher blood pressure in adolescent girls.

Preterm birth might induce permanent changes in vascular structure and function as well as in blood pressure. To elucidate this hypothesis and underlying mechanisms in girls born before term, the authors correlated neonatal data, including estradiol levels, with vascular function and structure and with blood pressure after puberty. In a case-control study design, 34 girls born before term and 32 gender- and age-matched control infants born at term were included. Pulse wave analysis was used to determine aortic pressure profiles and overall arterial compliance. Stiffness of the carotid artery and abdominal aorta was measured with ultrasonography. Pulse wave velocity in the forearm was measured with photoplethysmography. A laser Doppler technique was used to determine skin perfusion before and after transdermal delivery of acetylcholine, an endothelium-dependent vasodilator. It was found that preterm girls had significantly higher brachial and aortic blood pressure, a narrower but less stiff abdominal aorta, and lower peripheral skin blood flow than did control infants. Augmentation index, carotid stiffness, pulse wave velocity, endothelium-dependent vasodilatation, and heart rate were similar in the two groups. In the preterm group, blood pressure and vascular functions showed no association with intrauterine growth retardation or neonatal estradiol levels. In conclusion, preterm girls have higher blood pressure and an increased resistance in the vascular tree after puberty. These findings may have implications for future cardiovascular risk in the growing adult population surviving preterm birth.

TRANSEPIDERMAL WATER LOSS IN NEWBORN INFANTS I. Relation to Ambient Humidity and Site of Measurement and Estimation of Total Transepidermal Water Loss

Abstract. Insensible water loss (IWL) is an important factor in the thermoregulation and water balance of the newborn infant. A method for direct measurement of the rate of evaporation from the skin surface has been developed. The method, which is based on determination of the vapour pressure gradient close to the skin surface, allows free evaporation. From measurements performed on 19 newborns placed in incubators, a linear relation was found between the evaporation rate (ER) and the humidity of the environment at a constant ambient temperature. A 40% lower ER was recorded at a high relative humidity (60%) than at a low one (20%) in the incubator. At measurements on different sites of the body, a high ER was observed on the face and peripheral parts of the extremities, while ER at other sites was relatively low. By determining ER from different parts of the body and calculating the areas of the corresponding surfaces, the total cutaneous insensible water loss for the infant in question could be obtained. The transepidermal water loss (TEWL) for the whole body surface area was calculated to be 8.1 g/m2h. On the basis of measurements performed it was found that the total cutaneous insensible water loss can be estimated with a reasonable degree of accuracy by recording ER from only three easily accessible measurement points.

TRANSEPIDERMAL WATER LOSS IN NEWBORN INFANTS II. Relation to Activity and Body Temperature

Abstract. Using a method described in a previous article the transepidermal water loss (TEWL) was studied in 10 healthy newborn infants at rest and during activity. On the average TEWL was 37% higher during activity than during rest although no sweating was observed. In 9 infants placed in incubators with an ambient temperature slightly above the thermoneutral range measurements were made as the body temperature rose. TEWL was almost constant until a temperature of 37.1°C was reached whereupon the water loss suddenly increased as the infant started sweating.

Transepidermal water loss in infants born at 24 and 25 weeks of gestation

The rate of evaporation of water from the skin of 13 infants born at 24 (n= 3) and 25 (n= 10) weeks of gestation was measured on the first day after birth and at postnatal ages of 1,3,7 and 28 d, using the gradient method. Transepidermal water loss was estimated from this rate and corrected to an ambient relative humidity (RH) of 50%. Transepidermal water loss, corrected to 50% RH, was high on the first day after birth (58.4 ± 14.8gm 2 h?1) and remained at the same level during the second day (59.3 ± 17.6gm?2h?1). It then decreased significantly to 43.8 ± 9.5 at a postnatal age of 3 d, 36.1 ± 12.6 at 7 d and 24.2 ± 7.7gm?2h?1 at 28 d (p < 0.001). Within the group investigated, there was no significant correlation between transepidermal water loss and body or skin temperature, birth weight, gender, mode of delivery or gestational age. Transepidermal water loss on the first day after birth was somewhat lower than the highest losses previously found in infants born at 25 weeks of gestation, and of the same magnitude as previously reported for infants born at 25‐27 weeks. Transepidermal water loss at postnatal ages of 1,3,7 and 28 d in the present study was higher than that previously found in the group of infants born at 25‐27 weeks. In conclusion, in infants born at 24‐25 completed weeks of gestation transepidermal water loss was high immediately after birth and decreased with increasing postnatal age, but at a slower rate than previously reported for slightly more mature infants.

The Epidemiology of Sudden Infant Death Syndrome and Attacks of Lifelessness in Sweden

ABSTRACT. Infants who died showing the syndrome of sudden infant death (SIDS) and infants who survived attacks of lifelessness (AL) were examined in a prospective epidemiological multicentre study over 24 months covering close to 40% of all births in Sweden. Seventy SIDS cases and 34 cases of AL were observed, giving an incidence for SIDS of 0.94/1000 and for AL of 0.46/1000. This SIDS incidence is higher than that observed during the seventies. The boy/girl ratio was 1.4: 1 for SIDS and 1.6: 1 for AL. The age distribution for AL resembled that for SIDS. Similarities were also seen with regard to place of occurrence. Sixty per cent of the SIDS cases occurred during the daytime/evening. Twenty‐nine per cent of the infants with AL had more than one apneic spell during the three‐day‐period around the attack, indicating a period of respiratory instability, but only 12% had such spells later on. None of the infants who had had AL died from SIDS. The possible relationship between AL and SIDS is discussed.

Heat Loss from the Skin of Preterm and Fullterm Newborn Infants during the First Weeks after Birth

In 68 infants appropriate for gestational age, born after 25-41 weeks of gestation, the evaporation rate from the skin and ambient, skin and body temperatures were measured repeatedly during the first 4 weeks after birth, and the heat exchange due to evaporation, radiation and convection was calculated. All measurements were made at an ambient humidity of 50%, with the infants calm and quiet. High evaporative heat losses were found in preterm infants on their first days of life, with gradually decreasing values with increasing gestational and postnatal age. It was only during the 1st week of life in infants born at 25-27 weeks of gestation that evaporative heat loss was higher than radiative heat loss. The high evaporative heat losses in very preterm infants were balanced by low losses or even a gain through radiation and convection, because of the high ambient temperature needed to maintain a stable body temperature. Total heat loss increased with increasing gestational and postnatal age.

TRANSEPIDERMAL WATER LOSS IN FULL‐TERM AND PRE‐TERM INFANTS

Sedin, G., Hammarlund, K. and Strömberg, B. (Department of Paediatrics, University Hospital, Uppsala, Sweden). Transepidermal water loss in full‐term and pre‐term infants. Acta Paediatr Scand, Suppl. 305: 27–31, 1983.—The amount of water lost from the skin and the relation of the water loss to environmental factors, activity, body temperature, gestational age, nutritional status at birth and post‐natal age were studied in full‐term and pre‐term newborn infants. The method we used was non‐invasive and based on determination of the water vapour pressure gradient immediately above the skin surface. We found that the transepidermal water loss per unit time and area (TEWL; g/m2 h) could be calculated by using values from only three measurement sites. TEWL increased with activity and when body temperature was elevated above 37.1C. On the first day after birth TEWL in appropriate for gestational age (AGA) infants was exponentially related to gestational age, with much higher values in the most pre‐term infants than in full‐term infants. In full‐term small for gestational age (SGA) infants TEWL was significantly lower than in full‐term AGA infants. In pre‐term and full‐term AGA infants and in full‐term SGA infants we found an inverse linear relationship between ambient humidity and evaporation rate (ER; g/m2 h) from the skin. The level of ER and the slope of the relationship depended on the gestational age of the infant, with higher ER in the more pre‐term infants. Analysis of the relationship between ambient humidity and ER indicated that there is a gradual change in the permeability of the skin with gestational age. In pre‐term infants TEWL gradually decreased during the first weeks of life. In full‐term AGA infants TEWL was almost unchanged during these first weeks.

Water loss from the skin of term and preterm infants nursed under a radiant heater

The rate of evaporation from the skin (g/m2/h) was measured in 12 full-term and 16 preterm infants (gestational age 25–34 wk) both during incubator care and when nursed under a radiant heater. The method for evaporation rate measurement is noninvasive and based on determination of the water vapor pressure gradient close to the skin surface. Measurements were first made with the infant nursed in an incubator with a controlled environment with respect to humidity, temperature, and air velocity. The measurements in the term infants were performed at an ambient relative humidity (RH) of 50%, and in the preterm infants first at 50% and subsequently at 30–40%. Evaporation rate was then measured with the infant nursed under a radiant heater. In term infants, mean evaporation rate was 3.3 g/m2/h during incubator care (RH 50%) and 4.4 g/m2/h during care under the radiant heater. In preterm infants, the corresponding values were 15.5 g/m2/h in the incubator at RH 50%, 16.7 g/m2/h at RH 30–40%, and 17.9 g/m2/h under the radiant heater. It is concluded that the evaporative water loss from the skin depends on the ambient water vapor pressure, irrespective of whether the infant is nursed in an incubator or under a radiant heater. The higher rate of evaporation during care under a radiant heater is due to the lower ambient water vapor pressure and not to any direct effect of the nonionizing radiation on the skin.

Speech and language skills in children who required neonatal intensive care. II. Linguistic skills at 6½ years of age

Linguistic skills at 6½ y of age were examined in a cohort of 284 children requiring neonatal intensive care (NIC) and in 40 controls. Ten linguistic areas were assessed. The results are presented for gestational age groups. The 10th percentile score of the controls was identified in each linguistic area. Seventy percent of the controls and <27% of the NIC children had no score lower than the 10th percentile score. Scores lower than the 10th percentile score were more common in NIC children born at term or at 23–31 wk, and within the latter group in those born at 28–31 wk, than in those born at 32–36 wk gestational age. The linguistic areas of auditory discrimination, imitation of articulatory positions and imitation of sentences were most frequently affected. NIC children born at 32–36 wk performed better in the last two areas than those born at <32 wk. To be a twin and born at 28–31 wk was associated with an increased risk of having more than five scores lower than the 10th percentile score of the controls.