EFFECT OF ADENOSINE RECEPTOR BLOCKADE ON HYPOGLYCEMIA- INDUCED DILATIONS OF PIAL ARTERIOLES (PA) IN PIGLETS Vineta 1. Ruth*, Jeffrey M. Gidday, Ernesto R. Gonzales, T. S. Park. Department of Neurosurgery, Washington University Schwl of Medicine, St. Louis, Missouri, USA and *Children's Hospital, University of Helsinki, Helsinki, Finland. Hypoglycemia (HG) is associated with increased cerebral blood flow. We have shown dilation of PA in the newborn pigs during HG. To delermine if this is caused by the cerebral vasodilator adenosine (ADO), we studied the effects of 8- sulphophenyl-theophylline (8-SPT), an ADO receptor antagonist on HG-induced dilation of PA. A cranial window was implanted over the right parietal cortex of newborn pigs for observation of a selected PA (50-100 pm) by videomicroscopy at 20 rnin intervals. 2 pm changes in vessel diameter could be resolved. HG was induced by insulin in 9 matched control and 9 8-SPT piglets. In the latter group, the window was superfused (50 pl/min) with I@' M 8-SPT prior to manifest HG (blood glucose < 1.4 mmolll). RESULTS: PA diameter (mean f SEM; pm) are shown in table: * p<0.05 vs normoglycemia (NG); ** p<O.05 vs corresponding HG in controls. NG HG 20min HG 40min HG 60min HG 80min Control 68 f 3 90 f 5 * 93 f 6 * 93 f 8 * 100 + 8* 8-SPT 68 * 4 75 + 5 ** 75 f 6 ** 77 * 6 79 * 7 CONCLUSION: The attenuation of PA dilations by 8-SPT indicates that adenosine participates in the mediation of HG-related brain hypzremia. CEREBRAL BLOOD FLOW DURING HYPOXEMIA AND REOXYGENATION WITH 2 1 % OR 100% O2 IN NEWBORN P I G S . T e r j e R o o t w e l t , J a n - P. Odden, Christian Hall and Ola D. Saugstad. Inst. Surg. Res. and Dept. Ped. Res., Rikshospitalet, Oslo, Norway. To test the effects of resuscitation with 21% or 100% O2 on cerebral blood flow (CBF), hypoxemia was induced in 14 newborn pigs (2-5 days) by ventilation with 8% O2 in nitrogen. When base excess reached -20 mmol/L, they were randomly resuscitated with either 21% O2 (n=6) or 100% 0, (n=8) for 25 min followed by 21% O2 in both groups. Blood flow was measured in brainstem (BS), cerebellum (CBL) and cerebrum (CBR) with a radioactive microsphere method. Mean duration of hypoxemia was 59 min in both groups. Flow values were (ml/lOOg/min, meantSD): Hypoxemia Reoxygenation Before End o f 5 min 20 min 60 min BS 21% 80f23 140t31* 3102 99' 173?47* 89241 100% 85t28 176t88* 3551132' 161160* Elk24 CBL 21% 84t18 77t36 185t 65' 147t62* 84t43 100% 89131 94159 216t110" 134164* 84t26 CBR 21% 52t14 62t18 115t 29* 83?32* 44t14* 100% 53f20 73144 1181 51' 73?33* 52122 * p<0.05 compared t o before hypoxemia CBF was significantly increased in both groups in all areas after 5 and 20 rnin of reoxygenation. Conclusion: We could not demonstrate any significant differences in regional CBF between two groups of hypoxic newborn pigs reoxygenated with 21% or 100% 02. CEREBRAL BLOOD FLOW AND LEFT VENTRICULAR OUTPUT IN PREMATURE INFANTS AFTER 2 1 VERSUS 8 0 % OXYGEN AT BIRTH. Kaare E. Lundstrmm and Gorm Greisen. Dept. of Neonatology State University Hospital, Copenhagen, Denmark. Even short hyperoxaemia has been shown t o produce prolonged cerebral vasoconstriction in preterms. Cerebral blood flow (CBF) in preterms is less than in older infants and adults. We hypothesised that this may partly be due to exposure to exessive oxygen at birth. In a prospective, randomized study of infants < 32 weeks of gestational age we used 21 or 80 % oxygen during stabilisation/resuscitation in the delivery room. Two hours after birth, CBF was measured using Xe-clearance and left ventricular output (LVO) was calculated measuring the internal aortic diameter with M-mode echocardiography and aortic flow velocity using pulsed Doppler ultrasound. Results: This interrim analysis involves 30 infants, 14 randomized to 21 (GrI) and 16 randomized t o 80 % 02 (GrII). Supplemental oxygen was administered in the delivery room to two infants in Gr.1, and two hrs. after birth to 6 in GrI and 10 in GrII. Mean (SD) values in the groups (I/II) were CBF: 16.2 (5.7)/ 13.8 (4.7) ml/lOOq/min., p=0.21. LVO: 240 (58) / 263 (60) ml/kg/min., p=0.32. Conclusion: These preliminary results shows no diffence between the groups. Resuscitation with 21 % oxygen is possible in a majority of preterm infants. RESUSCITATION OF HYPOXIC NEWBORNS WITH ROOM AIR OR OXYGEN Siddarth Ramji, Gosta Rooth, and Ola D. Saugstad Department of Pediatrics, Maulana Azad Medical College, New Dehli, Department of Pediatrics, Uppsala, and Department of Pediatric Research, Oslo TO study the short term effects of resuscitation of hypoxic newborn babies with room air, a randomized multicenter study was initiated. Here the data from one center is reported. Entry criteria were: birth weight > 1000 gram, heart rate at birth < 80 per min and or apnoe justifying resuscitation. This was performed with bag and mask or after endotracheal intubation when needed. Babies were enrolled into a group treated with room air (RA, N=36) o r 100% oxygen (02, N=42). Bables in RA group who did not respond within 90 seconds were treated with supplementab oxygen. BW kq GA weeks Aqe: 1.breath l.crv resuscitation min RA 2.43 38.4 1.45 3.0 ** 2.3 * 0, 2.41 38.1 1.82 4.8 3.8 * pC0.05 ** D< 0 . 0 1 RA VS 0, qrOUDS ~eirt rate fkom birth to 10~kinutes and Apgar scores from 1 to 20 minutes were identical in both groups as well as pH, BE, paOz and paCO, a t 10 and 30 minutes post partum. Neonatal mortality was 2/36 in RA and 4/42 in 0, groups (NS) respectively. The study shows that judged by short term follow up hypoxic newborn infants may be resuscitated with room air just as well as with 100% O2. THERMAL BALANCE IN TERM INFANTS NURSED IN AN INCUBATOR WITH A RADIATIVE HEAT SOURCE Gunnar Sjors, Karen Hammarlund, Sveinn Kjartansson and Gunnar Sedin. Department of Pediamics. Uppsala University, Uppsala, Sweden. Radiative heat loss is an imponant mode of heat loss in convectively heated incubators. The "Transparent Radiant Hood Warmer" (Air Shields Vickers), a device that heats the roof of the Isolette C100 incubator, was used to study the response of 11 healthy, term infants exposed to an isolated change in roof temperature (T,,,'C) at stable ambient air temperature (T,,,,"C) and humidity (RH,%). Respiratory water loss (RWL,mg/kg min), oxygen consumption (VO,,ml/kg min), transepidermal water loss (TEWL,g,'m2 h), skin blood flow (Q,%, interval1 A=100%), skin CT,,"C) and central body (T,,"C) temperatures were continuously monitored. After an interval without active heating of the incubator roof (interval A), the roof was heated to 33°C (interval B) and then to 36°C (interval C). Mean values for each interval, including convective (H,,,,,W/m2 K) and radiative (H,,,,W/m2 OK) heat loss, are given in the table (*= p<0.01, compared to interval A). C 35.6* 32.6 50 35.9* 37.3* 104 20.7* 8.8 3.7 4.5 9.6 Conclusion: Warming the incubator roof results in a marked decrease in radiative heat loss, and an increase in skin and central body temperatures, without any significant change in skin blood flow, respiratory water loss, oxygen consumption or transepidermal water loss. TOTAL ENERGY EXPENDITURE (TEE) IN VENTILATOR DEPENDENT EXTREMELY- LOW-BIRTHWEIGHT (ELBW) INFANTS David C. Wilson, Charles M. Scrimgeour, Henry L Halliday, Mark Reid, Garth McClure, Michael J. Rennie. Department of Child Health, The Queen's University of Belfast, N. Ireland and Department of Anatomy and Physiology, The University of Dundee, Scotland Undernutrition due to inadequate energy intake and poor energy reserves is a major problem in ELBW infants who require prolonged mechanical ventilation. It is probable that raised TEE in these babies contributes further to the undernutrition but studies by indirect calorimetry are not possible. Our aim was to use the doubly labelled water method of TEE measurement in ELBW infants having prolonged ventilation. This method allows calculation of C02 production rate from the disappearance from the body of the stable isotopes deuterium and oxygen-18, and thus calculation of TEE. TEE was determined in 8 ventilator dependent ELBW infants (mean gestational age 24.9w, mean birthweight 7609) on 3 occasions. Energy intakes were calculated from exact records of enteral and parenteral intake. Results below are mean (SD). 3 weeks 6 weeks 10 weeks TEE (kcal/kg/d) 62.5(15) 68.0(27) 67.30 Energy intake (kcallkgld) 104( 17) 114(10) 119(4) Undernutrition in the first 10 weeks of life of sick ELBW infants is due both to Inadequate energy intake and raised TEE. Inadequate energy storage will not allow normal growth in these babies.Greater clinical priority should be given to improving the nutritional intake of the ELBW infant.