Epidemiology of respiratory syncytial virus infection requiring hospitalization in East Denmark.

BACKGROUND: Prophylaxis against infection caused by respiratory syncytial virus (RSV) with high titered RSV immunoglobulin or humanized antibody may soon be available in Europe. OBJECTIVE: To study the epidemiology of RSV infections requiring hospitalization in infants <6 months in East Denmark to provide a rational basis for decisions concerning prophylaxis against RSV. METHOD: Populat ion-based retrospective review of case records of infants <6 months admitted to pediatric departments with RSV infection in East Denmark from November 1, 1995, to April 30, 1996. RESULTS: Data were obtained from 459 infants. Seventy-three had predisposing conditions: prematurity, 49; pulmonary disease, 2; congenital heart disease, 7; neurologic disease, 6; others, 9. One preterm infant had bronchopulmonary dysplasia. The incidence of RSV infection requiring hospitalization in East Denmark among infants <6 months was estimated to be 34/1000/season. It was 32/1000/season among term infants and 66/ 1000/season among preterm infants (P<0.001). Infants with predisposing conditions and/or nosocomial infection (n = 24) had significantly more severe courses than otherwise healthy infants (P<0.01). One-hundred thirty infants received respiratory support by nasal continuous positive airway pressure, but only six required mechanical ventilation. No infants died. CONCLUSION: The course of RSV disease in East Denmark was milder than reported elsewhere, possibly as a result of the low prevalence of bronchopulmonary dysplasia in Denmark. However, RSV constitutes a considerable burden to the Danish pediatric health care system, and therefore prophylaxis against RSV is desirable.

The measurement of TcPO2 and TcPCO2 in newborn infants at 44 degrees C, 42 degrees C and 37 degrees C after initial heating to 44 degrees C.

Prolonged measurement of the transcutaneous O2 and CO2 tension at an electrode temperature of 44 to 45 degrees C often causes a second degree burn of the underlying skin. To avoid this, we compared the readings at 44 degrees C, 42 degrees C and 37 degrees C, after 2 hours pre-heating of the skin by the electrodes at 44 degrees C. In order to eliminate the electrodes' own temperature coefficients, electrodes with a built-in temperature correction were used. The changes observed therefore represent changes in the O2 and CO2 tension in the skin. The obtained values were compared to repeated arterial samples. We found that the TcPO2 and TcPCO2 values obtained at 42 degrees C and 37 degrees C were lower than those obtained at 44 degrees C, but when corrected for the in vivo temperature coefficients previously found by us the TcPO2 values at 42 were quite similar to the 44 degrees C values, whereas the 37 degrees values remained lower. TcPCO2 values at 44, 42 and 37 degrees were all similar. The temperature coefficient of PO2 was calculated to be 0.044 +/- 0.008 and for TcPCO2 as 0.049 +/- 0.007.

Catecholamine response to chest physiotherapy and endotracheal suctioning in preterm infants.

Adrenaline and noradrenaline was measured just before and just after chest physiotherapy and endotracheal suctioning in 13 preterm, ventilated, newborn infants. Mean aortic blood pressure was also recorded. Eight of the infants received phenobarbitone. Catecholamine levels were five-fold higher in the 5 infants with blood pH less than 7.30 compared to the other 8 infants. After the procedure, both adrenaline and noradrenaline were significantly higher than baseline levels. The adrenaline response to the procedure was a two-fold increase and significantly greater than the noradrenaline response. Analysis of the effects of phenobarbitone treatment and acidosis on catecholamine responses by multiple linear regression demonstrated that the adrenaline response was reduced by phenobarbitone while the noradrenaline response was unaffected. There were no associations of blood pressure, responses with catecholamine responses, with acidosis or with phenobarbitone treatment.

Evaluation of a transcutaneous oxygen and carbon dioxide monitor in a neonatal intensive care department.

Transcutaneous-PO2 (tc-PO2 (tc-PCO2) at 44 degrees C and transcutaneous-PCO2) at 38, 42, 43 and 44 degrees C were measured with a currently available monitoring system (TCM222, Radiometer, Copenhagen) in 64 newborn infants with severe respiratory insufficiency during the first five days of life. Tc-PCO2 at all four temperatures correlated better with arterial blood-PCO2 (aB-PCO2), than tc-PO2 with aB-PO2. However, the sensitivity and specificity of tc-PO2 and tc-PCO2 were similar with regard to maintaining aB-PO2 and aB-PCO2 within specified limits. Tc-PCO2 increased relatively with increasing electrode temperature by a factor which was similar to the anaerobic temperature coefficient of PCO2 in blood. The coefficient of variation of duplicate measurements was 10% for tc-PO2 and 5% for tc-PCO2. Electrode drift after an average of 3 hours patient monitoring was 2% +/- 6% (1 SD) for tc-PO2 and -3% +/- 6% for tc-PCO2. We conclude that tc-PO2 and tc-PCO2 are a valuable supplement to arterial blood gas measurements, but the variable correlation with arterial blood gas values and the electrode drifts which may occur, mean that they cannot fully replace arterial sampling.

Analysis of cranial 133-Xenon clearance in the newborn infant by the two-compartment model.

Cranial and chest clearance curves after intravenous administration of 133-Xenon was obtained on 112 occasions in 62 newborn infants admitted to our neonatal intensive care unit. The mean postnatal age was 5.1 days. The cranial clearance curves were submitted to two-compartment analysis. The compartmental clearance rate constants were 1.49 +/- 0.61/min and 0.099 +/- 0.033/min respectively while the fractional flow to the fast compartment was 0.51 +/- 0.14. Possible artefacts, particularly relevant to newborns, were analysed by computer simulation. It is concluded that the cranial 133-Xenon clearance curves varied considerably within the group of ill newborns and that the mean two-compartment parameter values differed considerably from those of healthy premature infants or adults, with or without cerebral illness. But the computer simulations demonstrated that the two-compartment parameters had high coefficients of variation and were significantly biased by right-to-left shunting of blood through the foramen ovale, by heterogeneity of the flow to the fastest compartment and by contamination of the cranial clearance curves by 133-Xenon in the airways. The radiation dose was 1.3 mGy to the lungs and 0.2 mGy to other tissues.

Relation between ionised calcium and pH in infants with acute acid-base disturbances.

Plasma ionised calcium, [Ca2+], and pH were negatively correlated in 21 infants with disturbed acid-base homeostasis. The slopes of the individual regression lines indicated a mean decrease in [Ca2+] of 42% per pH increase. (Mean delta log[Ca2+]/delta pH = -0.184, SEM = 0.050, p less than 0.001). The value was not significantly different from the relation between [Ca2+] and pH in vitro, when whole blood or plasma was equilibrated with CO2-air mixtures. pH and [Ca2+] must be measured and considered together to allow a proper interpretation of the result.