Systolic blood pressure in babies of less than 32 weeks gestation in the first year of life

AIM—To define the normal range of systolic blood pressure in a non-selective population based sample of babies of low gestation throughout early infancy.METHODS—Daily measurements of systolic blood pressure were made in all the babies of less than 32 weeks gestation born in the North of England in 1990 and 1991 during the first 10 days of life. Additional measurements were obtained from 135 of these babies throughout the first year of life. Systolic pressure was measured by sensing arterial flow with a Doppler ultrasound probe. It was assumed that blood pressure had never been pathologically abnormal in the neonatal period if the child was alive and free from severe disability two years later. Data of adequate quality were available from 398 such children. Additional data were collected, for comparative purposes, from 123 babies of 32, 36, or 40 weeks of gestation.RESULTS—Systolic pressure correlated with weight and gestation at birth, and rose progressively during the first 10 days of life. The coefficient of variation did not vary with gestational or postnatal age (mean value 17%), the relation with gestation being closer than with birthweight. Systolic pressure rose 20% during the first 10 days from an initial mean of 42 mm Hg in babies of 24 weeks gestation, and by 42% from an initial mean of 48 mm Hg in babies of 31 weeks gestation. These findings were not altered by the exclusion of data from 14 babies who had inotropic support during this time. Simultaneous measurements in three centres using an oscillometric technique revealed that this technique tended to overestimate systolic pressure when this was below average. Systolic pressure finally stabilised at a mean of 92 (95% CI 72-112) mm Hg at a postconceptional age of 44-48 weeks irrespective of gestation at birth.CONCLUSION—Systolic blood pressure 4-24 hours after birth was less than gestational age (in weeks) in only 3% of non-disabled long term survivors. Systolic pressure rose with increasing gestation and increasing postnatal age, but stabilised some six weeks after term, regardless of gestation at birth.     

Patent ductus arteriosus and retinopathy of prematurity in infants below 27 weeks gestation

Retrospective study of infants who survived the neonatal period after delivery at 24–26 weeks gestation revealed patency of the ductus arteriosus (PDA) in 44%. The mean birthweight of infants who developed PDA was lower. Retinopathy of prematurity (ROP) was seen in 79% of survivors with 24% having grade III or IV involvement. All but one of the more severe grades of ROP occurred among infants with PDA. Infants with PDA required more prolonged ventilatory support. Perinatal factors did not have a significant role in the development of these complications.     

Patent ductus arteriosus and retinopathy of prematurity in infants below 27 weeks gestation

Retrospective study of infants who survived the neonatal period after delivery at 24-26 weeks gestation revealed patency of the ductus arteriosus (PDA) in 44%. The mean birthweight of infants who developed PDA was lower. Retinopathy of prematurity (ROP) was seen in 79% of survivors with 24% having grade III or IV involvement. All but one of the more severe grades of ROP occurred among infants with PDA. Infants with PDA required more prolonged ventilatory support. Perinatal factors did not have a significant role in the development of these complications.     

Pulse oximetry, severe retinopathy, and outcome at one year in babies of less than 28 weeks gestation

AIM: To determine whether differing policies with regard to the control of oxygen saturation have any impact on the number of babies who develop retinopathy of prematurity and the number surviving with or without signs of cerebral palsy at one year. METHODS: An examination of the case notes of all the 295 babies who survived infancy after delivery before 28 weeks gestation in the north of England in 1990-1994. RESULTS: Babies given enough supplemental oxygen to maintain an oxygen saturation of 88-98%, as measured by pulse oximetry, for at least the first 8 weeks of life developed retinopathy of prematurity severe enough to be treated with cryotherapy four times as often as babies only given enough oxygen to maintain an oxygen saturation of 70-90% (27.2% v 6.2%). Surviving babies were also ventilated longer (31.4 v 13.9 days), more likely to be in oxygen at a postmenstrual age of 36 weeks (46% v 18 %), and more likely to have a weight below the third centile at discharge (45% v 17%). There was no difference in the proportion who survived infancy (53% v 52%) or who later developed cerebral palsy (17% v 15%). The lowest incidence of retinopathy in the study was associated with a policy that made little use of arterial lines. CONCLUSIONS: Attempts to keep oxygen saturation at a normal "physiological" level may do more harm than good in babies of less than 28 weeks gestation.     

Educational and behavioural problems in babies of 32-35 weeks gestation.

AIM: To identify incidence of school and behaviour problems at age 7 years in children born between 32 and 35 weeks gestation, and investigate perinatal risk factors. METHOD: The study population consisted of all children born at 32-35 weeks gestation to mothers resident in Oxfordshire in 1990. General practitioners, parents, and teachers were asked about health, behaviour, and education by postal questionnaire. Teachers rated children on level of function in six areas using a five point scale. They also completed the Strengths and Difficulties behaviour questionnaire. Perinatal risk factors were identified for children with poor school performance using a univariate and multivariate analysis. RESULTS: Teacher responses were obtained for 117 (66%) of the 176 children in the cohort. Twenty nine (25%) required support from a non-teaching assistant, five (4%) had required a statement of special educational needs, and three (3%) were at special school. Poor outcome was reported for 32% in writing, 31% in fine motor skills, 29% in mathematics, 19% in speaking, 21% in reading, and 12% in physical education. On the behaviour questionnaire, 19% of the cohort achieved an abnormal hyperactivity score (population norm 10%). Multivariate analysis showed perinatal variables that remained significant, independent of other variables; they were discharge from the special care baby unit > 36 weeks postconceptional age (odds ratio 4.15; 95% confidence interval 1.43 to 12.05) and male sex (odds ratio 3.88; 95% confidence interval 1.42 to 10.6). CONCLUSION: Up to a third of children born between 32 and 35 weeks gestation may have school problems. As there are larger numbers in this gestational category compared with smaller babies, this finding has implications for educational services.     

Closure of the ductus arteriosus: determinant factor in the appearance of transient peripheral pulmonary stenosis of the neonate

We speculated that a relationship may exist between transient peripheral pulmonary stenosis and the closure of the ductus arteriosus. Fifty preterm infants had pulmonary artery and ductal color Doppler flow velocity assessments performed before and after closure of the ductus arteriosus. No flow turbulence or increase in velocity was observed immediately after birth, although a significant discrepancy in size was observed between the main pulmonary artery and its two branches. After closure of the ductus, 15 infants had signs of transient peripheral pulmonary stenosis of the left pulmonary artery in association with a significant decrease of diameter at the origin of the same artery. In all 50 infants, no significant gradient was observed in the right pulmonary artery. We conclude that, at least in the preterm infant, transient peripheral pulmonary stenosis is not present at birth but is an acquired phenomenon closely related to closure of the ductus arteriosus.     

Premature membrane rupture in pregnancies of less than 34 weeks gestation

The outcome of pregnancies complicated by premature membrane rupture (PROM) at gestations of less than 34 weeks during a one-year period was reviewed. At presentation, infection was suspected in 12 of the 56 mothers, but confirmed in only three. All non-infected patients were then admitted to the ward and managed expectantly. Despite membrane rupture of up to 3-weeks duration, there were no episodes of proven maternal infection amongst the inpatients. Following delivery, seven babies had positive blood cultures; antenatal infection had been suspected, but not proven, in one case only. Four mothers developed postpartum infection which responded to antibiotic therapy. All mothers with infection, presenting either antenatally or postnatally, delivered within 48 h of membrane rupture and in all infected neonates the duration of membrane rupture was 72 h or less. The occurrence of sepsis was not related to the gestational age at onset of the membrane rupture. We conclude that patients with rupture of the membranes of 72 h duration or longer may be admitted for expectant management, even if presenting early in the second trimester, without an increased risk of infection.     

Hypernatraemia in preterm infants born at less than 27 weeks gestation

AIMS: To study the incidence of hypernatraemia (plasma sodium >145 mmol/L), identify predisposing factors to and associated complications of hypernatraemia in preterm infants born less than 27 weeks gestation in the first 5 days of life. METHODS: Preterm infants less than 27 week gestation over an 18-month period were studied by retrospective analysis of patient records. Data were collected on gestation, birthweight, sex, antenatal steroid use, phototherapy, incubator humidity, time of transfer to incubator, plasma sodium, urea and creatinine. Actual fluid and sodium intake was calculated for the first 5 days of life. Data were collected on chronic lung disease, patent ductus arteriosus, intraventricular haemorrhage, necrotising enterocolitis and death. RESULTS: In this study 46 (69.7%) of 66 infants studied developed hypernatraemia (>145 mmol/L), occurring most frequently between 24 and 48 h of age. The median gestation of hypernatraemic babies was significantly lower. There was no significant difference in median birthweight, or factors associated with increased insensible water loss between the hypernatraemic and the non-hypernatraemic groups. Fluid intake was significantly higher on days 2, 3 and 4 in the hypernatraemic group. There was no difference in sodium intake between the two groups. More hypernatraemic babies compared with controls developed chronic lung disease, patent ductus arteriosus, significant intraventricular haemorrhage, necrotising enterocolitis and died, but was not significant. CONCLUSION: Hypernatraemia occurs commonly in preterm infants less than 27 weeks gestation and was not associated with significant morbidity. The more immature infants developed hypernatraemia and all cases resolved after increasing fluid intake.     

Surfactant replacement therapy in neonates less than 32 weeks gestation: Effect on neonatal intensive care resource utilization

Abstract  The effect of synthetic surfactant (Exosurf) replacement on complications from hyaline membrane disease (HMD) in infants <32 weeks gestation and their resource utilization within a neonatal intensive care unit was studied in 1991-92. A control group was selected from infants admitted to the same unit during the preceding 3 years when Exosurf was not available. The infants were controlled for gestation, weight and severity of HMD.
Infants given Exosurf had a significant reduction in the incidence of pulmonary interstitial emphysema (PIE), and a marginal decrease in the incidence of pneumothorax. They required fewer days on the ventilator and consumed less of the scarce financial resources. There was no difference in the mortality rate among the two groups. The changes seen were more evident among those infants between 30 and 31 weeks gestation, compared to those <28 weeks.     

Effect of low-dose oral erythromycin on gastric aspirates in ventilated neonates less than 32 weeks of gestation. Preliminary results

In this prospective study, the 24-hour gastric aspirate volume was carefully recorded before, 24 and 48 h after administering 1.7 mg/kg/8-hourly of oral erythromycin to 16 ventilated neonates less than 32 weeks of gestation. Their median gestational age was 28.5 weeks (range 23-31 weeks), their median birthweight was 1,045 g (range 690-1,560 g) and the median day of life at which erythromycin was commenced was 9.5 days (range 4-16 days). Prior to administering erythromycin median 24-hour gastric aspirate volume, expressed as a percentage of the milk volume given over the same period, was 38.5% (range 20.0-100%). It was significantly lower 24 h (median 12%, range 0-41%, p = 0.0004) and 48 h (median 5%, range 0-21%, p = 0.0004) after commencing erythromycin. There was also significant reduction of gastric aspirate volume between 24 and 48 h after commencing erythromycin (p = 0.0024). Milk volume increment over the same period was not significant (p = 0.1022). These preliminary results warrant further evaluation through a randomised controlled trial.     

Rehospitalization for respiratory illness in infants of less than 32 weeks' gestation

All 133 surviving infants of gestational age less than or equal to 32 weeks born July 1, 1985, to June 30, 1986, as well as a socioeconomically matched full-term control group were observed prospectively for 2 years to determine the incidence of rehospitalization for respiratory illness. Perinatal and seasonal factors associated with increased risk for such hospitalizations were also examined. Forty-seven (36%) preterm infants were rehospitalized compared with 3 (2.5%) of 121 term infants (P less than .001). Preterm infants with and without rehospitalization were similar for mean birth weight (1104 +/- 329 g and 1188 +/- 360 g, respectively) and gestational age (28 +/- 2 weeks for both groups); however, infants who were subsequently rehospitalized had required more days of mechanical ventilation, supplemental oxygen therapy, and neonatal intensive care. While a history of bronchopulmonary dysplasia was a risk factor for rehospitalization (45% compared with 25% of those without bronchopulmonary dysplasia, P less than .05), preterm infants with no history of bronchopulmonary dysplasia still showed a 10-fold increase compared with control infants. Among the 43 infants who required no mechanical ventilation beyond the day of birth, 10 (23%) required rehospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of myocardial performance in preterm infants less than 29 weeks gestation during the transitional period

BackgroundThe transitional circulation and its effect on myocardial performance are poorly understood in preterm infants.AimsWe assessed myocardial performance in infants less than 29 weeks gestation in the first 48 h of life using a comprehensive echocardiographic assessment.DesignInfants < 29 weeks gestation were prospectively enrolled. Small for gestation, infants on inotropes and/or inhaled nitric oxide and septic infants were excluded. Conventional echocardiography, left ventricular (LV), septal and right ventricular (RV) tissue Doppler imaging (TDI) and tissue Doppler-derived strain and strain rate (SR), tricuspid annular plane systolic excursion (TAPSE) and global RV fractional area change (FAC) were assessed at a median of 10 and 45 h post-delivery.ResultsFifty-four infants with a median [IQR] gestation and birth weight of 26.5 weeks [25.8–28.0 weeks] and 915 g [758–1142 g] were included. There was no change in shortening or ejection fraction across the two time points. Systolic and diastolic TDI of the LV, septum and RV increased across the two time points (all p values ≤ 0.01). There was an increase in septal peak systolic and early diastolic SR (p = 0.002). Septal systolic strain and late diastolic SR did not change. With the exception of RV strain and early diastolic SR, all RV functional parameters including SR, late diastolic SR, TAPSE, and FAC increased across the two time points (all p values < 0.01).ConclusionDescribing the normal hemodynamic adaptations in stable preterm infants during the transitional period provides the necessary information for the assessment of those parameters in various disease states.     

Hyaline membrane disease and early neonatal aldosterone metabolism in infants of less than 33 weeks gestation

We studied urine excretion of free and conjugated aldosterone by 12 control infants and 14 infants with hyaline membrane disease (HMD) on the first and seventh days after birth. Both groups had a mean gestational age of 29 weeks. Total urine aldosterone excretion (UAE) and percent excreted as conjugate were similar for both groups on both study days, and did not relate to the severity of respiratory failure in infants with HMD. Sodium intake was higher for infants with HMD on both study days (p less than 0.02), but their urine sodium excretion was only significantly (p less than 0.01) higher on day 7. For total UAE values greater than 3 nmol/kg/d, there was no significant difference between estimated sodium-potassium exchange by control (22 +/- 5%, n = 8) and HMD (31 +/- 5%, n = 10) groups. These data suggest that neither the magnitude of excretion of aldosterone in the urine, the ability to conjugate aldosterone nor the degree of relative distal tubular unresponsiveness to aldosterone are related to the severity of pulmonary immaturity in preterm infants.