Volume 117 Number 5
however, did not include details of the test method used. Presumably the pool of immune globulin in these studies was derived from donors who, because of natural disease, had higher titers of measles antibody than had donors of pools prepared in the present era. W e found little variation among the four lots tested, but at dilutions of 1 : 100, E L I S A values were low. Current lots of immune globulin may contain far less measles antibody because they are derived from vaccinated donors, whose titers are low. The interpretation of low E L I S A values after administration of immune globulin is difficult because the pharmacokinetics of the intramuscularly administered preparation in neonates are not well described. However, sera drawn 48 hours after administration should reflect levels achieved after complete absorption of the intramuscular dose. Secondary cases among our infants probably did not occur because the infants were housed in incubators, making face-to-face contact with the infectious house officer less likely. Nevertheless, passive immunoprophylaxis with immune globulin should be considered if neonates are exposed to measles. If current preparations are confirmed to have relatively low titers of measles antibodies, a reassessment of the recommendations for passive prophylaxis or development of a hyperimmune measles globulin may be in order. We appreciate the assistance with statistical analysis provided by S. Amini, PhD, of the Department of Biostatistics, and are grateful to Karen Janiga and to the staff of the NICU, infection control, serology, and virology laboratories for their help.
Clinical and laboratory observations
785
REFERENCES 1. Centers for Disease Control. Measles prevention. MMWR 1987;36:409-25. 2. Centers for Disease Control. Measles 1988. MMWR 1989; 38:601-5. 3. Black FL. Measles.. In: Evans AS, ed. Viral infections of humans. New York: Plenum, 1989:451-65. 4. Krugman S, Giles JP, Friedman H, et al. Studies in immunity to measles. J PEDIATR 1965;66:471-88. 5. Gershon AA, Krugman S. Measles virus. In: Lennette EH, Schmidt N J, eds. Diagnostic procedures for viral, rickettsial and ehlamydial infections. Washington, D.C.: American Public Health Association, 1979:665-93. 6. Committee on Infectious Diseases. Measles. Evanston, II1.: American Academy of Pediatrics (Red Book), 1988:277-89. 7. Lennon JL, Black FL. Maternally derived measles immunity in era of vaccine-protected mothers. J PEDIATR 1986;108: 671-6. 8. Lipton SV, Brunnell PA. Management of varieella exposure in a neonatal intensive care unit. JAMA 1989;261:1782-4. 9. Hobbs JR, Davis JA. Serum ?-globulin levels and gestational age in premature babies. Lancet 1967;1:757-9. 10. Boteler WL, Luipersbeck PM, Fuccillo DA, et al. Enzymelinked immunosorbent assay for detection of measles antibody. J Clin Microbiol 1983;17:814-8. 11. Janeway CA. Use of concentrated human serum ?-globulin in the prevention and attenuation of measles. Bull NY Acad Med 1945;21:202-22. 12. Perkins FT. Passive prophylaxis of measles. Arch Virusforsch 1965;16:210-7.
Renal blood flow velocity in preterm infants with severe respiratory distress syndrome M a r g o t v a n d e Bor, MD, PhD, Frank v a n Bel, MD, PhD. G e r a r d L. Guit, MD, PhD, a n d J a a p S c h i p p e r , MD From the Division of Neonatology, Department of Pediatrics, and the Department of Diagnostic Radiology, University Hospital Leiden, Leiden, The Netherlands
Recovery from respiratory distress syndrome in preterm infants often begins after improvement of urinary output. 1 Whether prerenal or renal factors are responsible for inadequate outPut in these infants has not been elucidated. If prerenal conditions are involved, one might expect a
reduced renal blood ftow in these infants. In vitro and animal studies have demonstrated a good correlation between renal blood flow and renal blood flow velocity measurements.2,3 The aim of this study was to analyze with pulsed Doppler ultrasonography whether R B F V is impaired in preterm infants with severe RDS.
Submitted for publication Jan. 29, 1990; accepted May 17, 1990. Reprint requests: Margot van de Bor, MD, PhD, Division of Neonatology, University Hospital Leiden, Bldg. 35, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
METHODS
9/24/22431
Thirty-two infants whose birth weights were appropriate for gestational age (less than 32 completed weeks of gestation) and with severe R D S were enrolled in the study. Ges-
786
Clinical and laboratory observations
CO MABP MFV PI RBFV RDS
Cardiac output Mean arterial blood pressure Mean flow velocity Putsatillty index Renal blood flow velocity Respiratory distress syndrome
tational age was determined by maternal dates, Ballard scores, or both. 4 When there was a difference of more than 2 weeks, the latter was used. Severe RDS was defined on the basis of clinical and radiologic features (respiratory distress not attributable to other causes, need for assisted ventilation for more than 72 hours, and chest roentgenograms showing a fine, granular appearance throughout both lung fields with a peripherally extending air bronchogram (whiteout). Ten preterm infants without RDS, pneumonia, or congenital heart defect served as control subjects; an endotracheal tube was placed at birth and the infants received mechanical ventilation as part of the routine clinical care of infants less than 30 weeks of gestational age in our hospital. All enrolled infants had an umbilical artery catheter placed in situ. Infants with signs of hemodynamically significant patent ductus arteriosus diagnosed by Doppler echocardiography before the RBFV studies and infants receiving vasoactive drugs (e.g., dopamine, tolazoline, indomethacin) were excluded from the study. Infants who were small (90th percentile) for gestational age were not enrolled. The study was approved by the bioethics committee of our hospital, and informed parental consent was obtained. All infants were nursed in incubators (AGA type MK 241 [AGA, Lidingo, Sweden] or Draeger type 8000 [Draeger AG, Ltibeck, West Germany]). The humidity in the incubators was kept at approximately 80%, and the temperature was maintained according to the guidelines described by Hey and Scopes) None of the infants was nursed under a radiant heater. The blood flow velocity in the right renal artery was determined with two-dimensional, pulsed Doppler ultrasonography (Ultramark 4, Advanced Technology Laboratories, Inc., Bothell, Wash.). The transducer, with a 7.5 MHz imaging system and a 5.0 MHz Doppler crystal, was positioned below the costal margin in the dorsolateral area of the right flank. The sample volume of the Doppler system was set at 1.5 mm, and a 100 Hz high-pass filter was used to reduce the noise from the arterial wall. The sample volume was placed in the relatively straight proximal course of the right renal artery, 3 to 5 mm from the right side of the wall of the aorta. The artery was therefore insonated in an almost orthograde direction (0 to 25 degrees).6 Peak systolic (PSFV), end diastolic (EDFV), and temporal mean flow velocities, and the Pourcelot resistance index, or pulsatility index (PI = [ P S F V - E D F V ] / P S F V ) , were calculated from five sequential cardiac cycles. The measurements were performed between 24 and 36 hours after birth.
The Journal of Pediatrics November 1990
Before the RBFV studies, cardiac output (in milliliters per minute per kilogram) and stroke volume (in milliliters per kilogram) were measured with pulsed Doppler and Mmode echocardiography, as described previously.7 Simultaneously with the RBFV measurements, heart rate and mean arterial blood pressure from an indwelling umbilical artery catheter were recorded. Just before the Doppler studies, blood samples for arterial oxygen pressure, carbon dioxide pressure, pH, hematocrit, serum urea nitrogen, and creatinine measurements were drawn. Fluid intake and urinary output during the first 2 days of life were recorded. Student t tests were used to analyze the differences between the study and control groups. Stepwise regression analysis was used to determine the most predictive values for RBFV. A p value of
however, did not include details of the test method used. Presumably the pool of immune globulin in these studies was derived from donors who, because of natural disease, had higher titers of measles antibody than had donors of pools prepared in the present era. W e found little variation among the four lots tested, but at dilutions of 1 : 100, E L I S A values were low. Current lots of immune globulin may contain far less measles antibody because they are derived from vaccinated donors, whose titers are low. The interpretation of low E L I S A values after administration of immune globulin is difficult because the pharmacokinetics of the intramuscularly administered preparation in neonates are not well described. However, sera drawn 48 hours after administration should reflect levels achieved after complete absorption of the intramuscular dose. Secondary cases among our infants probably did not occur because the infants were housed in incubators, making face-to-face contact with the infectious house officer less likely. Nevertheless, passive immunoprophylaxis with immune globulin should be considered if neonates are exposed to measles. If current preparations are confirmed to have relatively low titers of measles antibodies, a reassessment of the recommendations for passive prophylaxis or development of a hyperimmune measles globulin may be in order. We appreciate the assistance with statistical analysis provided by S. Amini, PhD, of the Department of Biostatistics, and are grateful to Karen Janiga and to the staff of the NICU, infection control, serology, and virology laboratories for their help.
Clinical and laboratory observations
785
REFERENCES 1. Centers for Disease Control. Measles prevention. MMWR 1987;36:409-25. 2. Centers for Disease Control. Measles 1988. MMWR 1989; 38:601-5. 3. Black FL. Measles.. In: Evans AS, ed. Viral infections of humans. New York: Plenum, 1989:451-65. 4. Krugman S, Giles JP, Friedman H, et al. Studies in immunity to measles. J PEDIATR 1965;66:471-88. 5. Gershon AA, Krugman S. Measles virus. In: Lennette EH, Schmidt N J, eds. Diagnostic procedures for viral, rickettsial and ehlamydial infections. Washington, D.C.: American Public Health Association, 1979:665-93. 6. Committee on Infectious Diseases. Measles. Evanston, II1.: American Academy of Pediatrics (Red Book), 1988:277-89. 7. Lennon JL, Black FL. Maternally derived measles immunity in era of vaccine-protected mothers. J PEDIATR 1986;108: 671-6. 8. Lipton SV, Brunnell PA. Management of varieella exposure in a neonatal intensive care unit. JAMA 1989;261:1782-4. 9. Hobbs JR, Davis JA. Serum ?-globulin levels and gestational age in premature babies. Lancet 1967;1:757-9. 10. Boteler WL, Luipersbeck PM, Fuccillo DA, et al. Enzymelinked immunosorbent assay for detection of measles antibody. J Clin Microbiol 1983;17:814-8. 11. Janeway CA. Use of concentrated human serum ?-globulin in the prevention and attenuation of measles. Bull NY Acad Med 1945;21:202-22. 12. Perkins FT. Passive prophylaxis of measles. Arch Virusforsch 1965;16:210-7.
Renal blood flow velocity in preterm infants with severe respiratory distress syndrome M a r g o t v a n d e Bor, MD, PhD, Frank v a n Bel, MD, PhD. G e r a r d L. Guit, MD, PhD, a n d J a a p S c h i p p e r , MD From the Division of Neonatology, Department of Pediatrics, and the Department of Diagnostic Radiology, University Hospital Leiden, Leiden, The Netherlands
Recovery from respiratory distress syndrome in preterm infants often begins after improvement of urinary output. 1 Whether prerenal or renal factors are responsible for inadequate outPut in these infants has not been elucidated. If prerenal conditions are involved, one might expect a
reduced renal blood ftow in these infants. In vitro and animal studies have demonstrated a good correlation between renal blood flow and renal blood flow velocity measurements.2,3 The aim of this study was to analyze with pulsed Doppler ultrasonography whether R B F V is impaired in preterm infants with severe RDS.
Submitted for publication Jan. 29, 1990; accepted May 17, 1990. Reprint requests: Margot van de Bor, MD, PhD, Division of Neonatology, University Hospital Leiden, Bldg. 35, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
METHODS
9/24/22431
Thirty-two infants whose birth weights were appropriate for gestational age (less than 32 completed weeks of gestation) and with severe R D S were enrolled in the study. Ges-
786
Clinical and laboratory observations
CO MABP MFV PI RBFV RDS
Cardiac output Mean arterial blood pressure Mean flow velocity Putsatillty index Renal blood flow velocity Respiratory distress syndrome
tational age was determined by maternal dates, Ballard scores, or both. 4 When there was a difference of more than 2 weeks, the latter was used. Severe RDS was defined on the basis of clinical and radiologic features (respiratory distress not attributable to other causes, need for assisted ventilation for more than 72 hours, and chest roentgenograms showing a fine, granular appearance throughout both lung fields with a peripherally extending air bronchogram (whiteout). Ten preterm infants without RDS, pneumonia, or congenital heart defect served as control subjects; an endotracheal tube was placed at birth and the infants received mechanical ventilation as part of the routine clinical care of infants less than 30 weeks of gestational age in our hospital. All enrolled infants had an umbilical artery catheter placed in situ. Infants with signs of hemodynamically significant patent ductus arteriosus diagnosed by Doppler echocardiography before the RBFV studies and infants receiving vasoactive drugs (e.g., dopamine, tolazoline, indomethacin) were excluded from the study. Infants who were small (90th percentile) for gestational age were not enrolled. The study was approved by the bioethics committee of our hospital, and informed parental consent was obtained. All infants were nursed in incubators (AGA type MK 241 [AGA, Lidingo, Sweden] or Draeger type 8000 [Draeger AG, Ltibeck, West Germany]). The humidity in the incubators was kept at approximately 80%, and the temperature was maintained according to the guidelines described by Hey and Scopes) None of the infants was nursed under a radiant heater. The blood flow velocity in the right renal artery was determined with two-dimensional, pulsed Doppler ultrasonography (Ultramark 4, Advanced Technology Laboratories, Inc., Bothell, Wash.). The transducer, with a 7.5 MHz imaging system and a 5.0 MHz Doppler crystal, was positioned below the costal margin in the dorsolateral area of the right flank. The sample volume of the Doppler system was set at 1.5 mm, and a 100 Hz high-pass filter was used to reduce the noise from the arterial wall. The sample volume was placed in the relatively straight proximal course of the right renal artery, 3 to 5 mm from the right side of the wall of the aorta. The artery was therefore insonated in an almost orthograde direction (0 to 25 degrees).6 Peak systolic (PSFV), end diastolic (EDFV), and temporal mean flow velocities, and the Pourcelot resistance index, or pulsatility index (PI = [ P S F V - E D F V ] / P S F V ) , were calculated from five sequential cardiac cycles. The measurements were performed between 24 and 36 hours after birth.
The Journal of Pediatrics November 1990
Before the RBFV studies, cardiac output (in milliliters per minute per kilogram) and stroke volume (in milliliters per kilogram) were measured with pulsed Doppler and Mmode echocardiography, as described previously.7 Simultaneously with the RBFV measurements, heart rate and mean arterial blood pressure from an indwelling umbilical artery catheter were recorded. Just before the Doppler studies, blood samples for arterial oxygen pressure, carbon dioxide pressure, pH, hematocrit, serum urea nitrogen, and creatinine measurements were drawn. Fluid intake and urinary output during the first 2 days of life were recorded. Student t tests were used to analyze the differences between the study and control groups. Stepwise regression analysis was used to determine the most predictive values for RBFV. A p value of
