M. Lindroth

Respiratory distress syndrome in infants with impaired intrauterine growth

The recently introduced intrauterine growth curve, based on ultrasonically estimated foetal weights, was retrospectively applied to an inborn population of 883 infants bom before 33 gestational weeks at the University Hospital of Lund, during 1985–94. The estimation of birthweight deviation resulted in 630 (71.3%) infants with a birthweight appropriate for gestational age (AGA), 244 (27.6%) infants with a birthweight small for gestational age (SGA) and 9(1.1%) infants with a birthweight large for gestational age. Birthweight deviation was associated with an increased mortality [odds ratio (OR) adjusted for gestational age 1.29 per SD (12%) change in birthweight for gestational age, 95% CI: 1.10–1.50; p= 0.002]. At gestational age 25–28 weeks, SGA‐infants had an increased incidence of respiratory distress syndrome (RDS) as compared to AGA‐infants (OR adjusted for gestational age: 1.98,95% CI: 1.12–3.52; p= 0.019). At gestational age 29–32 weeks, SGA‐infants had a lower incidence of RDS as compared to AGA‐infants (OR adjusted for gestational age: OR 0.52,95% CI: 0.34–0.80; p= 0.003). After adjustment for confounding variables, infants born at gestational age 25–28 weeks from mothers with pre‐eclampsia, appeared to be a high‐risk group for RDS, whereas at the age of 29–32 gestational weeks, negative birthweight deviation had a protective effect against RDS. Antenatal corticosteroid administration appeared to have a less beneficial effect on mortality, RDS and cerebral haemorrhage in infants born SGA vs in those born AGA.

Low risk of seizure recurrence after early withdrawal of antiepileptic treatment in the neonatal period.

The risk of seizure recurrence within the first year of life was evaluated in infants with neonatal seizures diagnosed with a combination of clinical signs, amplitude-integrated electroencephalogram (EEG) monitoring, and standard EEG. Fifty eight of 283 (4.5%) neonates in tertiary level neonatal intensive care had seizures. The mortality in the infants with neonatal seizures was 36.2%. In 31 surviving infants antiepileptic treatment was discontinued after one to 65 days (median 4.5 days). Three infants received no antiepileptic treatment, two continued with prophylactic antiepileptic treatment. Seizure recurrence was present in only three cases (8.3%)--one infant receiving prophylaxis, one treated for 65 days, and in one infant treated for six days. Owing to the small number of infants with seizure recurrence, no clinical features could be specifically related to an increased risk of subsequent seizures. When administering antiepileptic treatment, one aim was to abolish both clinical and electrographical seizures. Another goal was to minimise the duration of treatment and to keep the treatment as short as possible. It is suggested that treating neonatal seizures in this way may not only reduce the risk of subsequent seizure recurrence, but may also minimise unnecessary non-specific prophylactic treatment for epilepsy.

EVALUATION OF MECHANICAL VENTILATION IN NEWBORN INFANTS: I. Techniques and survival rates

Abstract. Lindroth, M., Svenningsen, N. W., Ahlström, H. and Jonson, B. (Neonatal Unit, Department of Paediatrics, University Hospital, Lund, Sweden). Evaluation of mechanical ventilation in newborn infants. 1. Techniques and survival rates. Acta Paediatr Scand, 69: 143, 1980.—The short‐term outcome with survival rate, causes of death and neonatal complications in a 6‐year material comprising 253 infants treated with intermittent positive pressure ventilation (IPPV) in the neonatal period has been analyzed in relation to different primary disorders necessitating IPPV treatment. The total survival rate was 53%. For the different diagnoses the survival rates were: hyaline membrane disease (HMD) 41%, apnoea repetens of immaturity 85%, severe birth asphyxia 46% and septicemia 59%. The total rate of pneumothorax during IPPV was 15% but occurred more often in the HMD group (28%). Trends in survival rates over the study period are discussed as are measurements for improvements.

Association between low concentrations of antibodies to protein alpha and Rib and invasive neonatal group B streptococcal infection.

Background: Infection with group B streptococci (GBS) is a serious neonatal disease. The GBS cell surface proteins α and Rib elicit protective immunity in animal models and have been suggested as potential antigens in a vaccine against human GBS disease. Aims: To test the hypothesis that transplacentally transferred maternal antibodies to GBS proteins contribute to the protection of the neonate from GBS infection. Methods: Thirty neonates with invasive infection were included in a case-control study. IgG antibody concentrations were measured in sera from these neonates, their mothers, and from 60 non-infected controls, neonates as well as mothers. Results: A clear association was found between concentrations of antibody to proteins α and Rib in neonatal and maternal sera, indicating that transplacental transfer had occurred. Moreover, low concentrations of antibodies to α and Rib in neonatal sera were associated with invasive GBS infection caused by strains expressing the Rib protein. The odds ratio was 0.0007 (95% confidence interval 0.000 to 0.54) for antibodies to α and 0.002 (95% confidence interval 0.000 to 0.57) for antibodies to Rib. Conclusion: These findings support the notion that antibodies to GBS surface proteins contribute to the protection against neonatal infection.

Pulmonary Mechanics in Early Infancy. Sublinical Grunting in Low-Birth-Weight Infants

Summary: Pulmonary mechanics were studied with the constant pressure body plethysmograph method in 78 infants during the first year of life. Registrations of breathing frequency, tidal volume, minute volume, dynamic compliance, pulmonary functional resistance, and end-expiratory resistance were made at rest and during carbon dioxide-induced hyperventilation. Data from 70 infants demonstrated strong correlations (P < 0.001) between all pulmonary function parameters and length. Carbon dioxide-induced hyperventilation was achieved mainly by an increased tidal volume. Pulmonary functional resistance did not change with hyperventilation, indicating wider airways during forced ventilation.A special breathing pattern called “subclinical grunting” was found in 16 of 45 infants who were low birth weight but without clinical signs of hyaline membrane disease. The pattern was characterized by a high resistance during most of the prolonged expiration. It was identical to that previously described in cases of hyaline membrane diseases. All re-examined low-birth-weight infants with subclinical grunting developed a normal breathing pattern.Speculation: Sublinical grunting found in preterm low-birth-weight infants might be a phenomenon of postnatal lung adaptation which can be registered by pulmonary mechanics examination.

Appropriate prophylaxis with restrictive palivizumab regimen in preterm children in Sweden

Aim: Palivizumab (Synagis®) was registered in Sweden in 1999 for prophylaxis against respiratory syncytial virus (RSV) in premature infants. The high costs and the limited knowledge of the efficacy of this substance have led to debate about how and when it should be used. National guidelines for the use of palivizumab in Sweden were constructed in the year 2000. The aim of this study was to evaluate the guidelines. Methods: A nation‐wide prospective study was conducted during the two RSV seasons of the years 2000–2002. The paediatric departments in Sweden reported the use of palivizumab, the indication for its use, and the number of infants born preterm before 36 wk of gestation and less than 2 y old who were admitted to hospital for RSV infection. Results: During the two seasons, 218 (3.8%) children who were born before 36 wk of gestation, and 97 (5.4%) who were born before 33 wk, were hospitalized because of RSV infection. Five children were treated with mechanical ventilation. No death caused by RSV was reported. A total of 390 children were treated with palivizumab, and 16 (4.1%) of those who received prophylactic treatment were admitted to hospital with RSV infection.

PULMONARY MECHANICS, CHEST X-RAY AND LUNG DISEASE AFTER MECHANICAL VENTILATION IN LOW BIRTH WEIGHT INFANTS

Abstract. Lindroth, M., Jonson, B., Svenningsen, N. W. and Mortensson, W. (Neonatal Unit, Department of Paediatrics, University Hospital, Lund, Sweden). Pulmonary mechanics, chest X‐ray and lung disease after mechanical ventilation in low birth weight infants. Acta Paediatr Scand, 69:761, 1980.—Pulmonary mechanics, chest X‐ray and the incidence of clinical lung disease were studied in 41 low birth weight infants treated with intermittent positive pressure ventilation (IPPV) in the neonatal period. Shortly after IPPV most patients, irrespective of X‐ray findings, had signs of lung damage reflected in low dynamic compliance or high pulmonary resistance. Both parameters, however, had a strong tendency towards normalization during the first year of life. Overdistention on chest X‐ray was common at 6–12 months of age. Pneumonia and bronchitis were common during the first two years of life but subsided later on. Development of BPD or later respiratory disease were not correlated to treatment with high inspired oxygen concentrations but commonest in patients with hyaline membrane disease. The combined findings of pulmonary mechanics and chest X‐ray shortly after IPPV were correlated to later clinical lung disease.

Continuous positive airway pressure: modes of action in relation to clinical applications.

Some physical effects of CPAP are discussed, as are the various devices used for CPAP in infants. Some of the controversies about CPAP may be related to the unsuitability of certain techniques. Use in hyaline membrane disease, extrathoracic and intrathoracic airway obstruction, congestion of overperfusion of the lungs in diseases of the heart and great vessels, apnea repetens of immaturity, and phrenic nerve palsy is presented.

Changing trend in perinatal management and outcome of extremely low birthweight (ELBW) infants

Perinatal care of the extremely preterm and low birthweight (ELBW) infant is founded on basic principles of physiology and knowledge about the prevailing pathophysiological mechanisms. New therapies in clinical care are usually introduced non‐uniformly, so more often there is a gradual rather than a sudden change in the development of perinatal care, conceivably involving also an important learning process. This was confirmed in an evaluation of respiratory care for ELBW infants (n = 325) over a 9‐year period (1986–1994). Although birthweight (mean 815 g) and degree of immaturity at birth (mean 26.7 weeks of gestation) did not change over the years, our trend analysis showed that the survival rate increased from 47% to 70% (p < 0.04) and the percentage of survivors without bronchopulmonary dysplasia and/or major intracranial haemorrhages (ICH grades 3 and 4) increased from 67% to 87% (p < 0.006). We suggest that besides medical treatment per se, refinement and tuning of nursing and medical care procedures will also affect the total outcome of ELBW infants.

Diuresis and Urine Concentration during CPAP in Newborn Infants

ABSTRACT. The impact of continuous positive airways pressure (CPAP) on diuresis and urine concentration was studied in newborn preterm infants with respiratory insufficiency with and without pulmonary X‐ray changes. Urine output and osmolality, sodium balance and blood pressure were measured before, during and after CPAP application. In all infants urine osmolality rose and urine output decreased significantly when high CPAP (8 cm H2O) was applied, especially in infants without radiographic pulmonary changes. Three infants also developed hyponatremia at high CPAP levels. The results indicate that high CPAP levels per se may affect fluid balance inadvertently. Therefore fluid intake and urine output should be monitored closely during CPAP treatment.