228 Neonatal Skin Surface Pco2 Obtained With Unheated and Heated Transcutaneous Electrodes

Abstract

The inherent characteristics of nonheated (NH) and heated (H) transcutaneous PC02 electrodes (PtcC02) favor their application in different clinical conditions. Knowledge of factors affecting NHP tcC02 values and of changes induced by HPtcC02 electrodes is necessary for their clinical use. 24 infants, BW 840 to 4240 gms., GA 24 to 43 wks were studied at ages 8 to 110 hrs. HPtcCO2 at 430C and 4 4 O~ were monitored and related to PaC02. Good correlations with PaCO have been demonstrated for NHPtcCO (r.8), 430C (r.86) and 4 4 O~ fr.91) HPtcC02, (all with p<.001). ~2 e factors analyzed were: maturity, body weight, sex, postnatal age, and the use of radiant warmers (RW) and incubators (I). Results for NHPtcC02: preterm infants had PtcCO2 higher by 4mmHg than term infants (PC. 005). Infants weighing 2500 qrms. (n=17) had mean PtcC02 levels 4mmHg higher than larger infants (n=8) (~(~01). Postnatal age did not affect PtcCO2. There were no differences between genders. Mean PtcC02 were higher in infants in I than RW (p<,01). In asymptomatic prematures with PDA, values from right infraclavicular area were lower (p<.001) than those from other areas of the body studieg. All differences found for NHPCOL disappeared when 43OC and An assay for carbonic anhydrase activity was developed which measures pH deflection rate from the hydration of dissolved Cop. Enzymatic activity is expressed as ml C02 hydration catalysis per minute per mg Hgb or lung tissue protein at 22O C. Fetal RBC carbonic anhydrase activity correlated significantly with gestational age, rising from 14.9 '3 to 34.9 +4 ml CD2 hydration per minute/mg Hgb at 2 2 ' C. Adult red cell activity was 84.6 *13. Lung tissue carbonic anhydrase activity was fndependant of that in RBC, and ranged from 3.2 a1.3 to 6.1 A1.8 ml C02/min per mg lung protein, and directly correlated with fetal lung liquid CI-/HC03-ratios, peaking at 27 days gestation then decreasing to the levels found at term and In the adult rabbit lung. The susceptibility of mice to develop experimental diabetes vary among different inbred strains. 65 mice are more resistant to develop diabetes than KsJ mice due to the ability of their islet cells to undergo hypertrophy, These differences may manifest also during transplantation. Twelve 6J mice were made diabetic with streptozotocin given at 1 mg per gm body weight and 12 KsJ mice with 0.5 mg per gm. A week later islet cells from 6 week old normal 6J and KsJ mice were transplanted into the kidney capsule of the diabetic mice. Pancreas tissue from two normal 6J and two KsJ mice were minced with scissors into fragments about 0.5 to 1 mm in Hauk'ssolution and immediately transferred into the renal capsule of the 63 and KsJ diabetic host respectively, The course of the diabetes was followed by determination oi plasma glucose. The pre transplantation mean fSD glucose was 524'119 in 65 and 529f76 mgIper'100 ml in KsJ, and the post transplantation was 263'134 in 6J and 426'135 mgfper 100 ml in KsJ. Islets containing beta cells were stained with aldehyde fuchsin and fou...