Richard W. Krouskop

The early use of continuous positive airway pressure in the treatment of idiopathic respiratory distress syndrome

Infants with IRDS were treated with CPAP early (0.40 Fi O 2 O 2 ; Pa O 2 O 2 (maximum 0.55) and had a less severe clinical course. The late treated infants were subjected to 0.70 or more Fi O 2 for an average of 24 hours and were in greater than 0.40 Fi O 2 significantly longer than those given CPAP early. Infants who weighed less than 1,500 gm and had severe disease did not do well regardless of when CPAP was applied.

Accuracy and clinical utility of an oxygen saturation catheter.

Twenty-three fiberoptic catheter oximeters were placed in the umbilical arteries of 22 neonates to determine the accuracy and reliability of the sensor and clinical utility of continuous measurement of arterial oxygen saturation. Comparison of fiberoptic saturation readings with 1039 bench measured blood samples revealed a correlation coefficient of 0.97 with a mean error of 0.74 +/- 2.17 (SD) saturation. Although 11 catheters remained reasonably accurate (in error less than 3% saturation) for up to 488 h of use, 12 required in vivo calibration at a median time of 31 h after initial insertion. Clinical use of the catheter oximeter was evaluated in 11 infants by comparison to matched controls. Control infants required 55% more arterial blood samples for care, twice the number of transfusions, and spent twice the amount of time with a PaO2 greater than 110 torr. The catheter oximeter was found to be a useful clinical tool. Saturation values up to 95% reflected accurately and reliably an infants arterial saturation status, providing constant and comprehensive assessment of clinical variations and the effects of therapy. The most useful feature was its rapid and accurate response to hypoxic incidents and to efforts to correct these conditions for improved care of infants in life-threatening situations.

Blood volume and blood pressure in infants with respiratory distress

Mean aortic blood pressure volume were measured in true premature infants with respiratory distress syndrome. Seven infants had Type I RDS (hyaline membrane disease) and ten had transient tachypnea of the newborn (Type II RDS). Blood volume in the infants with Type I RDS was significantly lower than in the infants with Type II RDS. The difference was due to a low red cell volume. Mean aortic blood pressure was within the range of normal in all infants and therefore did not reflect the low blood volume of infants with Type I RDS. Normal mean aortic blood pressure does not indicate normal blood volume or normal circulation in infants with RDS.

THE RELATIONSHIP OF FEEDING TO NECROTIZING ENTEROCOLITIS

The records of all newborns with necrotizing enterocolitis (N-E) were reviewed for the years 1968-73. Of the 24 cases, 19 died & N-E was confirmed in all 18 autopsies. The previously reported associations with low birth weight, PROM or amnionitis, asphyxia, & RDS were found. Also, a relationship with feeding was seen—the infants forming 3 groups: Group I-18 infants begun on formula feedings between 4 hrs. to 8 days of life. They developed G.I. signs an average of 31 hrs. later (S.E.=5.6). Formula intake by the 2nd day of feeding averaged 72 cc/kg/day, 133% of the usual daily formula intake in this nursery for infants without overt illness. All 5 who lived (of which none perforated or had surgery) were in this group. Group II-3 infants developed the onset of G.I. signs 15, 20 and 28 days following initiation of feeding, but had other intercurrent problems. Group III-3 infants never fed formula. These had no x-ray or autopsy evidence of pneumatosis. In these 24 patients with N-E, 75% developed the disease related to the onset of feeding. The remainder appeared to develop their disease in relationship to other problems. Formula feeding in this series is very closely associated with the development of N-E, particularly over-aggressive feeding. Feeding is not the sole cause of N-E but is closely enough related to its development to warrant delayed and cautious feeding of infants at risk of N-E.

The relationship of maternal erythrocyte oxygen transport parameters to intrauterine growth retardation

The relation of fetal growth and maternal oxygen transport as assessed by red blood cell 2,3-diphosphoglycerate, hemoglobin oxygen affinity, hemoglobin, pH, and PCO2 was evaluated in 21 pregnant women. The study was performed in the third trimester and each subject evaluated had sonographic evidence of fetal growth retardation without other obvious abnormalities. Decreased maternal 2,3-diphosphoglycerate/hemoglobin molar ratio and hemoglobin oxygen affinity were related linearly to the birth weight normalized for the expected sea level values of gestational age expressed as a birth weight (gestational age-normalized) Z score. The correlation coefficients and p values were r = 0.71, p less than 0.001 and r = 0.67, p less than 0.001, respectively. The ponderal index-normalized Z score correlated with the 2,3-diphosphoglycerate/hemoglobin molar ratio (r = 0.46, p less than 0.04), but the relation was not as strong as the birth weight-normalized Z score. The crown-heel length/head circumference ratio did not correlate with the 2,3-diphosphoglycerate/hemoglobin molar ratio (r = 0.29, NS). The birth weight (gestational age)-normalized Z score did not correlate with hemoglobin, PCO2, or pH. In the regulation of hemoglobin oxygen affinity, calculations indicated that the 2,3-diphosphoglycerate/hemoglobin molar ratio played a highly significant role (p less than 0.001), pH was minimally significant (p less than 0.025), but PCO2 had little or no significant effects in this study. It appears that fetal growth is related to the maternal red blood cell oxygen transport parameters 2,3-diphosphoglycerate/hemoglobin molar ratio and hemoglobin oxygen affinity. Moreover, the 2,3-diphosphoglycerate/hemoglobin molar ratio is the principal regulator of hemoglobin oxygen affinity.

Intrauterine growth retardation related to maternal erythrocyte oxygen transport.

Intrauterine growth retardation (IUGR),. is a term applied to fetuses who, at any week of gestation, are undersized for the duration of pregnancy. IUGR is a common problem contributing to 3.5% to 43% of all births (Lin and Evans, 1984). These infants frequently have asphyxia, meconium aspiration, persistent fetal circulation, polycythemia, hypoglycemia and congenital malformations. The causes of IUGR are diverse and can be attributed to maternal, fetal, placental or other unknown factors. Included in the latter group is a subset with inadequate oxygenation whose etiology remains elusive.

LOW BLOOD VOLUME WITH NORMAL SYSTEMIC BLOOD PRESSURE IN INFANTS WITH HYALINE MEMBRANE DISEASE |[lpar]|HMD|[rpar]|

The central circulating blood volume (CCBV) was evaluated in 17 neonates with respiratory distress, 6 of whom had HMD. The infants were evaluated clinically and by strict radiographic criteria before entering the study at 1-2 hours of age. No small-for-dates infants were included. Measurements using I125 albumin were made on each infant at 4 & 24 hours. Mean pressures were measured in the aorta continuously for 12 hours and at 24 hours. Hematocrit determinations were done at birth, 4 & 24 hours. The mean blood volume of infants with HMD and other forms of respiratory distress was 86.6 and 100 ml/kg respectively (P < 0.01). The difference was due to low red cell volume, mean 38.2 and 47.5 ml/kg (P < 0.02). The hematocrit values at birth and 4 hours were not statistically different indicating that low CCBV in the HMD group is not the result of an inadequate placental transfusion. It is curious that the CCBV at 4 & 24 hours was not statistically different despite whole blood or other fluid infusion. Mean pressures of each group during the first 12 hours and at 24 hours were not statistically different and correlated well with norms previously established for prematures. Our data show that 1) blood pressure and hematocrit measurements are poor parameters for estimating CCBV; 2) the low red cell volume in HMD appears to exist prior to delivery; 3) and implies that vasomotor activity adequately maintains mean aortic pressures in the HMD group.

PERINATAL FACTORS UNDERLYING NEONATAL CHOLESTASIS

We evaluated prolonged use of total parenteral nutrition (TPN) and the effects of perinatal factors in infants who developed neonatal cholestasis (CH). Only infants <1500 gms at birth admitted to our Intensive Care Nursery during the first 3 days of life who survived >2 weeks, had no GI disease and received TPN ⩾14 days were studied; 40 infants met these criteria. 19 infants developed CH (direct bilirubin > = 1.5 mg/dl >1 week) and 21 did not. Infants who developed CH received TPN longer than those without CH (P <0.01). However, the mean duration (± 1SD) of TPN at the onset of CH was 32 ± 13 days while the mean duration (± 1SD) of TPN in the uneffected infants was 33 ± 16 days (P = NS).Infants with CH compared to those without CH had a greater frequency of hypotension (P <0.01) and severe hyaline membrane disease (P <0.01), although no differences were observed in birth weight, gestational age, Apgar scores, and the first blood gas results. These findings indicate that among immature infants, severe systemic and pulmonary hypoperfusion (shock) appears to damage the liver to the degree that during TPN its impaired excretory function is overwhelmed, leading to CH.

A PERINATAL RESEARCH DATABASE

A computerized perinatal database has been developed at Mount Sinai Hospital to manage information generated by 7000 admissions per year (3500 maternal & 3500 infant), including 900 admissions to the Newborn Special Care Unit. The unique features of this database system occur in 3 areas.1. It was designed from inception as a comprehensive, integrated maternal-infant database. There are currently 534 maternal and 646 infant variables. The database is designed to prospectively collect data of general utility to any perinatal research study enabling integration of that data with the specialized data collected by specific research.2. The database is distributed over two separate computer systems to be cost-effective, yet allow complex use of the data. Data are entered on a 16-bit multi-user micro-computer where admission notes, discharge summaries, and summary reports on < 1 years data are generated. Data are regularly transmitted from the local computer to our University Computing Center where complex statistical analysis, long-term analysis, and archival storage are available.3. Data collection has been integrated into routine medical care, utilizing problem oriented records to allow prospective data collection rather than retrospective chart abstraction.

1348 IN-VIVO CALIBRATION IMPROVES THE RELIABILITY OF TRANSCUTANEOUS (Tc) OXYGEN MONITORING

We have found a wide variability in correlation between PTcO2 and PaO2 under usual clinical conditions; r=.75 for 432 data pairs in 14 sick infants. We felt this poor correlation resulted from patient variation (range of r=.43 → .98 for each infant).To test this hypothesis we devised and evaluated the usefulness of an in-vivo calibration procedure. Prior to each 4 hour application to the skin, the Tc sensor was calibrated in room-air per manufacturers instructions. PaO2 was measured > 20 min. < 1 hr. after application. The resulting error in estimation of PaO2 by PTcO2 was calculated [Error = (PaO2 - PTcO2)/PaO2]. If this was >.15, the Tc monitor was calibrated by adjusting its gain to a new value (calibrated PTcO2) calculated from the present PTcO2 reading (raw PTcO2) and the Error [calibrated PTcO2 = raw PTcO2/(Error -1)]. Subsequent PaO2 and PTcO2 data pairs comprised the study data. Control data for each infant was obtained during alternative time periods by following the same initial procedure, but no in-vivo calibration was performed. In 10 infants, the PaO2 vs PTcO2 correlation for study data was 0.93, while only 0.80 for control data. 34.4% of all applications were > our 15% error tolerance. Consequently, in-vivo calibration utilizing one arterial blood gas within each 4-hour application provides a more accurate estimate of PaO2 from the transcutaneous monitor. However, an increased work load is imposed on nursery staff.