Errol R. Alden

OXYGEN CONSUMPTION OF INFANTS UNDER INFRARED RADIANT ENERGY WARMERS

Overhead radiant warming devices facilitate the care of sick newborn infants. However, no data are available on the energy ex penditure)oxygen consumption)of infants under radiant energy warmers compared to conventional incubators. This study was conducted to compare oxygen consumption of normal, two day old full term infants subjected to non-ionizing radiant warmers(KDC-CC-660) and to conventional incubators(Servo-Care Armstrong Incubators, Ohio Medical Products). Oxygen consumption was determined using the “closed system technique” employing nasal prongs, a CO2 analyzer the Beckman OM-11 O2 analyzer and the Hewlett Packard (HP). Pneumotach with attachments to the respiratory integrator of the HP 7700 multichannel recording system. All infants were fed 20 minutes prior to each recording period. Each infant was alternately placed on the radiant warmer and the incubator(servo-control set to 36.5 ° C)and after an initial stabilizing period of 20-30 minutes the O2 consumption was determined for 3-5 minutes while in quiet sleep (characteristic EEG, ECG, muscle activity and respiration).The skin temp and heart rate were respectively, radiant warmer 36.6 ° C and 136 b/m and incubator 36.1 ° C and 135 b/m. These findings support the hypothesis of increased oxygen consumption in infants on radiant energy warmers.

Children, Gender, Education, and Health

* Abbreviation: SDG — : sustainable development goal In this month’s Pediatrics , Alsan et al1 address one of the factors contributing to inequities in education for girls in low- and middle-income countries. By using data from 38 countries’ demographic and health surveys, they analyze the differential impact of childhood illness and maternal work outside of the home on school attendance for adolescent boys and girls in households. Over one-third of houses sampled had children who were not in school, and more than half had a child <5 years with an illness in the past 2 weeks. Presumably because girls and women are more often required to take on traditional child-caretaking roles, the authors demonstrate a small but significant effect on girls’ education, worse with increasing poverty and maternal illiteracy. A 5.1% disparity for school attendance by gender in households without ill children increased with one or more illness to 7.8% and 8.5%, respectively. Similarly, when mothers worked outside the home, the gender was 6.1% with no illnesses, and rose to 8.7% and 10.6% with one or more than one episodes of illness in children <5 years of age. Their analyses suggest that … Address correspondence to Jonathan D. Klein, MD, MPH, NCD Child, 820 N Prospect Ave, Park Ridge, IL 60068. E-mail: jklein60068{at}gmail.com

Effect of resuscitative fluids upon physical properties of blood perfusing the brain.

Acute physiologic changes induced by the infusion of resuscitative fluids may be harmful, resulting in the clinical sequelae of pulmonary and intraventricular hemorrhage. Using a chronically catheterized lamb model, changes in plasma sodium concentration, osmolality, hematocrit, glucose, colloid osmotic pressure, and arterial pressure were quantified in blood directly perfusing the brain, following distal infusions of fluids commonly used during neonatal resuscitation: molar and .5M NaHCO3, D10W and D25W, and whole blood. Distal infusion of hypertonic solutions resulted in acute alterations in electrolyte and osmotic equilibrium in the common carotid artery. All infused solutions caused a brief elevation in mean blood pressure; whole blood transfusion resulted in a sustained increase in blood pressure.

1385 CEREBRAL BLOOD FLOW (CBF) AUTOREGULATION IN THE NEWBORN LAMB WITH HYPOVOLEMIC HYPOTENSION WITHOUT AN ASSOCIATED ANEMIA

We have shown that the newborn lamb maintains CBF when mean arterial blood pressure (MAP) is lowered to 30 mmHg by hemorrhage. Independent measurements of both hematocrit (HCT) and arterial O2 content [O2]a fel1 nearly 40%. Although O2 delivery (O2D) decreased, O2 consumption (MVO2) was maintained. Because HCT and [O2]a are determiners of CBF, we attempted to control those variables in 6 anesthetized lambs (< 7 days old). HCT was maintained within physiological limits by infusing autologous packed RBCs. CBF was measured with radioactive microspheres. MAP was reduced (with a pressurized reservoir connected to a catheter in the abdominal aorta) from control to 50, 40 & 30 mmHg.CBF and O2D were maintained and MVO2 increased in the newborn lamb model of hypotension without anemia. Since the HCT and [O2]a were well controlled, this study documents that the newborn lamb can autoregulate CBF over the range of MAP of 96-28 mmHg. If O2D is maintained (non-anemia), MVO2 increases. If O2 demand is as great in anemic-hypotensive newborns; the inability of O2D to adequately supply this demand may result in ischemia.

REGIONAL DISTRIBUTION OF BLOOD FLOW WITH HYPOVOLEMIC HYPOTENSION IN THE NEONATAL LAMB

We studied the blood flow (BF) to and vascular resistance (VR) of vital tissues in 7 anesthetized newborn lambs in response to hypovolemic hypotension. BF was measured with radioactive microspheres injected into the left ventricle; blood pressure (BP) and arterial blood samples were taken from axillary arteries. BP was reduced by phlebotomy in three steps in each lamb.Calculated VR decreased in the heart, brain and adrenals and increased in the kidney and spleen. However, VR in the small intestine was not changed with hypotension. These data indicate that in the neonatal lamb the vascular response of the intestine to hypotension may be different than that of other abdominal visceral organs. Supported by USUHS grants C08631 and C08626.

Alveolar instability with inspired 100% O2 in the newborn lung

Right to left shunt determinations in newborn infants have suggested that alveoli are unstable with inspired oxygen concentrations of 100%. Theoretically alveoli with very low VA/Q ratios should collapse with inspired 100% oxygen, resulting in a decrease in alveolar-arterial nitrogen difference (A-ADN2) and an increase or no change in alveolar-arterial oxygen difference (AaDO2), and an increase or no change in shunt.Four newborn lambs were ventilated at constant tidal volume initially with 40% oxygen for 1½ hours, then with 100% oxygen for 3 hours and then returned to 40% oxygen for 1½ hours. Arterial and mixed venous blood was sampled at the end of each period and analyzed for PO2, PN2, PCO2. Alveolar PO2 and PN2 were calculated.Three lambs (Table) had a large number of alveoli with very low VA/Q. Decrease in a a-ADN2, with an increase in A-aDO2 and shunt, indicates conversion of alveoli with very low VA/Q to alveoli with collapse.One lamb had a small number of alveoli with low VA/Q. In this animal no changes were anticipated nor found with 100% O2 inhalation.It is concluded that in the newborn period, alveoli with very low VA/Q may collapse with inspired 100% O2.