Quality of survival after artificial ventilation of the newborn

Pulmonary testing using peak flow meters of very low birth weight children born in the perisurfactant era and school controls at age 10 years

We determined lung function at age 10 years in very low birthweight (VLBW, <or=1,500 g) children and controls, and compared the sensitivity to detect subgroup differences by peak expiratory flow (PEF), forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC) and their diurnal variation. VLBW children were recruited across the perisurfactant era at admission to six NICUs in Wisconsin and Iowa, and controls from area classrooms. Two hundred sixty five VLBW children and 360 controls were tested by the Jaeger AM1 peak flow meter at age 10 years. Two hundred six VLBW and 79 controls had additional home monitoring. Abnormality was defined as observed/predicted ratio <0.8 for PEF, FEV(1), and FVC, and by criteria of Pelkonen for diurnal PEF variation. VLBW children were compared to controls, VLBW children with bronchopulmonary dysplasia (BPD) to those without, and those with respiratory conditions to those without. PEF and FEV(1) showed high reproducibility (intraclass correlations, ICC 0.75-0.83). Controls and VLBW children with and without BPD differed significantly on all measures. Baseline test results did not differ across birth years, but PEF variation was less after surfactant availability (P = 0.04). Observed over predicted FEV(1) was the most sensitive in detecting differences between groups (P < 0.001), with mean (s.d.) 0.97 (0.12) for controls, 0.88 (0.14) for VLBW children without BPD, and 0.78 (0.13) for those with BPD. Odds ratios for abnormality were especially high with respiratory medication use during the first 5 years of life, 4.4 (95% CI: 2.0-9.8) for FEV(1) and 5.1 (95% CI: 2.0-13.2) for diurnal PEF variation. Our results show that respiratory abnormalities persist to at least age 10 years for VLBW children born in the surfactant era.

Lung function and respiratory health in adolescents of very low birth weight

AIMS

To determine if very low birth weight (VLBW; birth weight <1500 g) is associated with reduced lung function and respiratory health in adolescence and, if it is, whether this impairment is associated with prematurity or intrauterine growth restriction.

METHODS

A geographically defined cohort of 128 VLBW infants and an age, sex, and school matched comparison group born in 1980/81 were studied. The cohort and comparison group were assessed at 15 years of age. The birth weight ratio of the index cases (observed birth weight/expected birth weight for the gestation) was determined to assess the degree of growth restriction. Respiratory support received during the neonatal period was obtained from hospital records. Smoking habits and respiratory morbidity were obtained through questionnaires. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and forced expiratory flow when 25-75% of FVC is expired (FEF(25-75%)) were measured using a portable spirometer. The values are expressed as percentage predicted for height, age, and gender using standard reference values. Adjustments were made for smoking habits of mother and children.

RESULTS

The differences in means between index and comparison groups for FEF(25-75%) (-12.42%; p < 0.001) and FEV1/FVC (-3.53%; p < 0.001) ratio were statistically significant. The differences in FVC and FEV1 were not significant. No correlation was found between the birth weight ratio and lung function among the index cohort. Chronic cough, wheezing, and asthma were more common among the index cohort than in the comparison group. Within the index group, there was no difference in lung function between those who received and those who did not receive respiratory support.

CONCLUSION

Adolescents who were VLBW compared with matched controls showed medium and small airways obstruction. This was associated with prematurity rather than intrauterine growth restriction or having received respiratory support during the neonatal period. The index VLBW cohort compared with their controls were also more prone to chronic cough, wheezing, and asthma.

Long-term outcome of infants born preterm

This chapter outlines some of the many long-term health problems to be expected in surviving preterm children. They have higher rates of sensorineural impairments (such as cerebral palsy, and visual, auditory and intellectual impairments) and sensorineural disabilities from these impairments, than children born at term. In addition, they grow poorly and have higher rates of other health problems, including poorer respiratory health in early childhood. There is little doubt that preterm children contribute disproportionately to the prevalence of health problems in childhood. However, there are still many gaps in our knowledge of the outcome for preterm survivors, particularly regarding outcome in adulthood. Obstetricians and neonatologists working in intensive care, as well as parents, want to know the long-term outcome for preterm children born today, not that of children born a generation ago when fewer preterm children (particularly those of extremely low birthweight) survived. Despite the many problems, the conclusion is that most preterm children are as healthy as term children, suffering only usual childhood illnesses; we feel confident that the majority make, and will continue to make, useful contributions to their families and the societies in which they live.

Is low birth weight a risk factor for asthma during adolescence?

The effect of low birth weight on the incidence of asthma by 17 years of age was investigated by studying medical draft examination records of 20,312 male subjects born in Jerusalem between January 1967 and December 1971. Additional information on birth weight and other demographic factors was abstracted from the Jerusalem Perinatal Study computerised database. A stepwise multiple logistic regression was used to estimate the odds ratios for developing asthma by 17 years of age in 500 g birthweight categories from less than 2000 g to 4500 g. The odds ratios were adjusted for the confounding effects of ethnic origin, social class (determined by area of residence), paternal education, maternal age, and birth order. The group with low birth weights (less than 2500 g, n = 1004) had a significantly increased risk of developing asthma by 17 years of age, with an adjusted odds ratio of 1.44 (95% confidence interval (CI) 0.79 to 2.66) for birthweight group less than 2000 g and 1.49 (95% CI 1.05 to 2.12) for birthweight group 2000-2499 g compared with the reference group of 3000-3499 g. We conclude that infants with birth weights of less than 2500 g may have a higher risk of asthma during childhood and adolescence than infants who were heavier at birth.

Speech and language development after infant tracheostomy

This study describes the speech/language development of 31 children who had been fitted with an endotracheal tube. Intubation in all cases occurred prior to 13 months of age and remained in situ for more than 3 months. These children were chosen from a pool of 130 potential subjects. Individuals diagnosed as having a primary neurological disorder, developmental delays, or mental retardation were excluded from the study. Demographic, birth, and medical factors that might also affect language outcome were documented. Standardized outcome measures were used to assess speech, language, and cognitive development of the children seen for testing. For the entire group of children, the overall measures of language functioning at follow-up were within normal limits and commensurate with cognitive ability. However, when a breakdown of results based on the children's ages was done, a clear pattern of language disability was noted in the expressive language of the oldest group of children tested. These findings raise questions about this group of children who were previously thought to develop speech and language skills normally.

Lung function in children of low birth weight

Lung function was recorded in a cohort of 130 age specific children of low birth weight (under 2000 g) and a reference population of 120 unselected local schoolchildren at 7 years of age. Children of the cohort were similar in height and forced vital capacity to the reference group, but had significantly reduced forced expiratory volume in 0.75 second and expiratory flow indices. Although neonatal respiratory illness was associated with reduced airway function, we were unable to confirm that this was a consequence of oxygen treatment or mechanical ventilation. Low birth weight, however, was closely associated with poor airway function independent of neonatal respiratory illness. Other factors of importance included the male gender and maternal smoking. The reduction in airway function observed in the low birthweight children was associated with cough but not wheeze. The disparity between the relatively well preserved vital capacity and reduced airway function suggests that very low birth weight, and hence prematurity, has its greatest effect on the subsequent growth of airway function. The absence of an association between neonatal oxygen score or mechanical ventilation and childhood lung function suggests that the long term effect of neonatal respiratory treatment is small compared with that of birth weight, maternal smoking, and male sex.

Respiratory symptoms in children of low birth weight

We recorded the respiratory history by questionnaire in a 7 year old cohort of children whose birth weight was under 2000 g and an unselected reference group of local schoolchildren of the same age. Complete data were obtained in 121 low birthweight children (90% of those studied): 62 who had no neonatal respiratory illness, 25 who had oxygen treatment only, and 34 who received mechanical ventilation (of whom 10 had bronchopulmonary dysplasia). The low birthweight children were no more likely to wheeze than the reference group, but frequent and troublesome cough was significantly more common, especially among children of very low birth weight (under 1500 g) who had received neonatal respiratory treatment. Neonatal mechanical ventilation was not associated with increased symptoms when compared with neonatal oxygen treatment alone. The prevalence of cough at the age of 7 was independently associated with the level of neonatal intensive care as defined by oxygen score. Although there was no excess of wheeze in the cohort compared with the reference group, there was a weak correlation between wheeze and the neonatal oxygen score as well as with maternal smoking. Loss of schooling due to respiratory symptoms in the nine months before this study was no greater in children of low birth weight than in the reference group.

Cardiorespiratory function in asymptomatic survivors of neonatal respiratory distress syndrome

We measured cardiopulmonary function at rest and during exercise in 15 healthy survivors of neonatal respiratory distress syndrome (RDS) and compared the results with those in 15 normal subjects. The mean birth weight of the RDS group was 1,771 g, and 12 of the 15 patients had required endotracheal intubation. The oxygen scores ranged from 79 to 3,322. Five of the 15 RDS patients had abnormal results of pulmonary function studies at rest. Peak expiratory flow was lower (P less than 0.05) in the RDS group (2.98 liters/min) than in the control group (3.57 liters/min). A negative correlation was noted between the forced expiratory flow between 25 and 75% of vital capacity and the oxygen score in these patients. Exercise tolerance was below normal in two of the RDS patients, both of whom also had abnormal pulmonary function at rest. One patient in the RDS group had systemic arterial hypertension at rest and during exercise. No significant differences in exercise tolerance or the cardiorespiratory response to exercise were observed between the two groups.

Differential maturation of cortical auditory evoked potentials to speech sounds in normal fullterm and very low-birthweight infants

Cortical auditory evoked potentials (AEP) to the consonant-vowel syllables/da/and/ta/and 800Hz tone were recorded at 40 weeks post-conceptional age and at one, two and three months after term in normal fullterm and very low-birthweight infants. As a group, the very low-birthweight infants exhibited significantly less mature AEPs to consonant-vowel syllables than the normal-birthweight infants at 40 weeks post-conceptional age. Consistent but statistically non-significant differences also were found for tones at 40 weeks post-conceptional age, and for all stimuli at one and two months after term. By three months, all the infants exhibited mature AEP morphology and topography.

Communication development in young children with long-term tracheostomies: preliminary report

Communication development was studied in 77 subjects with long-term tracheostomies ranging in age from two months to 7 years. Children were categorized according to tracheostomy status (cannulated or decannulated), presence of speech practice prior to cannulation, and level of language development (prelinguistic or linguistic) at the time of decannulation. All were aphonic and consequently deprived of speech experience for extended periods while tracheostomized. Twenty-three children have been studied post-decannulation. Results for the children decannulated during the prelinguistic stage revealed that speech and language skills were attained commensurate with intellectual functioning. This evidence led to the conclusion that extensive, audible prespeech practice (cooing and babbling) was not needed for later spoken language development. All children decannulated during the linguistic stage exhibited specific spoken language delays including phonological impairment at the time of decannulation. The presence of speech practice prior to cannulation did not appear to be a factor in the severity of phonological impairment. The children who were cannulated for more lengthy time periods, extending into the linguistic stage, however, demonstrated more severe phonological impairment than those who were decannulated during the prelinguistic stage. With direct speech/language therapy, 20 of the 23 decannulated children eventually compensated for these difficulties, demonstrating appropriate spoken language skills. Alternative communication modalities were felt to be crucial in reducing communicative frustrations during cannulation.

A follow-up of the survivors of mechanical ventilation in a paediatric intensive care unit

Fifty-eight long-term survivors of mechanical ventilation have been traced and examined for evidence of auditory, visual, behavioural, developmental and central nervous system abnormalities. There were four children with serious neurological or intellectual handicaps, the causes of which did not seem to be related to deficiencies of their ventilator treatment but rather to events preceding ventilation or to the disease which had necessitated ventilation. There were an additional eight children who may have some intellectual damage. The occurrence of convulsions or hypoxic episodes during or preceding the period of treatment was significantly more common among the 12 children with a poor outcome, than those with a good outcome.

Pulmonary sequelae of neonatal respiratory distress in very low birthweight infants: a clinical and physiological study

Twenty infants, mechanically ventilated in the neonatal period for respiratory distress syndrome, were compared with 15 healthy controls, matched for birthweight(less than 1501 g) but greater in mean gestational age. Clinical features and lung mechanics (by whole body plethysmography) were recorded at 6-monthly intervals until about one year. THe neonatal course of the mechanically ventilated infants was commonly complicated by tracheobronchial hypersecretion and the later course by a fairly high incidence of lower respiratory tract illness. In this group, thoracic gas volume, dynamic compliance, pulmonary and airways conductance were all abnormal during the middle 4 months of the first year and reverted towards normal towards the end of the first year. The control group had normal lung mechanics. Early lung function tests were of limited value in predicting later lower respiratory tract illness, which was more common in boys, after neonatal mechanical ventilation for longer than 24 hours or raised ambient oxygen for longer than 5 days. There were few predictive physical signs. In this group of very low birthweight infants, respiratory distress syndrome of sufficient severity to require mechanical ventilation led to significant physiological and clinical disturbances of lung function which lasted into the second 6 months of life and which were particularly severe in those who had recurrent lower respiratory tract illness.

Growth and development in children recovering from bronchopulmonary dysplasia

Of 26 patients with bronchopulmonary dysplasia, 20 (77%) survived and were followed prospectively for two years post-term. Lower respiratory tract infections occurred in 17 of the 20 children (85%), and required hospitalization in ten (50%) during the first and in four (20%) during the second year. At two years post-term only two patients had significant respiratory symptoms at rest, but 78% had residual radiographic changes. The average weight and height at term were at or below the third percentile. Growth occurred at an accelerated rate with improvement of respiratory symptoms, with average weight reaching the third to tenth percentile for both sexes, and tenth to twenty-fifth percentile for height in the boys and the twenty-fifth percentile for the girls by two years post-term. Growth retardation was associated with severe and prolonged respiratory dysfunction. Fifteen (75%) were free of major developmental defects. Five had mean Bayley scores less than 85 at 18 months post-term; one also had hydrocephalus. Developmental outcome seems related to perinatal and neonatal events rather than to the presence or absence of BPD.

Long-term prognosis of infants with idiopathic respiratory distress syndrome. Follow-up studies in infants surviving after the introduction of continuous positive airway pressure

Fifty-one children surviving IRDS with CPAP alone or CPAP and IPPV were studied at the age of 2.5 to 4.0 years. One child had developed tetraplegia and mental retardation and 6 children were speech-retarded. Correlation with perinatal events showed that this group of children had a significantly lower gestational age and birth weight, a lower Apgar score and a higher PCO2 prior to ventilatory treatment than the remainder. Re-examination by age 4.0 to 5.0 years showed persistent handicaps in only four of the seven children.

Hyaline membrane disease: prognostic factors and medium-term follow-up

One hundred and twenty two cases of severe hyaline membrane disease are reported. 68 of them survived (57%). Adverse clinical, radiological and laboratory factors, and their effects on the early mortality rate, are analysed with particular reference to the referring centers, delay in admission, transport and the critical state of most infants on admission. The follow-up of 29 survivors treated before 1974 has been examined with reference to birthweight and assisted respiration. Four (30%) of the twelve infants with birthweights below 2000 g had major neurological sequelae. Only two out of the 17 babies with a birthweight over 2000 g had minor mental disturbances.

Prognosis of neonates with symptomatic respiratory insufficiency surviving with the aid of ventilator therapy

Twenty-one survivors representing all survivors of neonatal symptomatic respiratory distress treated with intermittent positive pressure ventilation have been follow-up at an age of 2.9 to 7.0 years. The chance of survival proved to be relatively favourable in infants ventilated for perinatal pneumonias and unfavourable in infants ventilated for haemorrhagic diseases and respiratory insufficiency secondary to surgical conditions. At the follow-up half of the children presented with neurological symptoms but only 10% were found severely handicapped. One infant had a tracheostomy due to a laryngeal stenosis, while none developed broncho-pulmonary dysplasia. The late prognosis seemed unfavourable when the children had suffered from severe birth asphyxia and in infants ventilated for prolonged recurrent apnoeic spells. The relation between the clinical indications for ventilator therapy and later outcome is obscured however, by a vase number of complicating perinatal events.

Long term prognosis of infants with severe idiopathic respiratory distress syndrome. I. Neurological and mental outcome

76 out of 77 children surviving IRDS with the aid of intermittent positive pressure ventilation have been followed-up by the age 2.6-7.6 years together with 68 matched controls. Moderate or severe neurological, developmental or mental abnormalities were present in 17% of all IRDS survivors. Statistical comparison of the matched pairs of IRDS survivors and controls revealed no significant differences in the prevalence of abnormalities. In the IRDS survivors the occurrence of cerebral palsy related to prematurity while the development of psycho-motor and mental retardation related to low birth weight and low milk intake during the first week suggesting that both prenatal and postnatal growth retardation may have been of importance. Statistical analysis of a number of preventilatory and ventilatory parameters did not show significant differences between these groups of IRDS survivors and the remainder. Ventilator treatment is recommended as a promising adjunct to the therapy of severe IRDS in centers where the necessary experience and equipment is at hand.

Neurological sequelae in children surviving mechanical ventilation in the neonatal period

The incidence of mental defect, visual and hearing disability, major neurological handicap, and such minor neurological handicap as can be detected on examination at 2--9 years without formal intelligence testing, is presented among survivors of neonatal mechanical ventilation at Hammersmith Hospital between the years 1966--1973 inclusive. 77(21%) of 367 children survived, over three-quarters of them being born elsewhere. 3 died before the age of 6 months, 2 suddenly and unexpectedly at home, the third accidentally. 1 child was lost to follow up. 11 (15%) of the remaining 73 children had neurological sequelae as defined. In two-thirds this was moderate to severe. Spastic diplegia may no longer be the commonest form of cerebral palsy among those of low birthweight, particularly those surviving severe neonatal illness.

Intermittent positive pressure ventilation in infants and children. The Long term effects in 74 survivors

Seventy-four infants and children surviving after more than 12 hours IPPV are discussed with reference to long-term physical and mental development.

Continuous postive airways pressure treatment by a face chamber in idiopathic respiratory distress syndrome

Continuous positive airways pressure treatment by a face chamber in idiopathic respiratory distress syndrome. During a 3-year period 45 infants with idiopathic respiratory distress syndrome (IRDS) requiring ventilatory support were treated in the neonatal unit. Continuous positive airways pressure (CPAP) via the face chamber was applied as initial therapy in 39 infants and during weaning from initial intermittent positive pressure ventilation (IPPV) treatment in 5 infants, whereas 1 infant received IPPV only. Among the 39 infants initially treated with CPAP 9 required IPPV as well. The overall survival rate was 37/45 or 82%. Incapacity to hyperoxygenate while breathing 100% oxygen was the indication for CPAP while occurrence of apnoeic attacks was the indication for IPPV. Pao2 during the hyperoxia test before ventilatory support was less than 50 mmHg in 10 infants and between 50 and 105 mmHg in 35 infants. Surviving infants were followed up with neurological and developmental control examinations as well as chest x-ray, and in several infants pulmonary function tests. 3/37 infants had moderate neurological sequelae and only 1/37 infants developed bronchopulmonary dysplasia. No deleterious effects of the face chamber were seen. As the face chamber is a noninvasive and easily applied technique for CPAP therapy without hazards, it is proposed that it should be used at a still earlier stage of IRDS in order to lesson the need for IPPV treatment and to increase the neurological and lung functional quality of survival.

Respiratory insufficiency syndrome (RIS) in preterm infants with gestational age of 32 weeks and less. Neonatal management and follow-up study

The clinical entity of respiratory insufficiency syndrome (RIS), i.e. irregular breathing leading to recurrent apnea and bradycardia in an otherwise healthy preterm infant, has been studied in respect of symptomathology and management with intensive case including ventilatory support. During a 4-year period 26 of 103 infants with gestational age less than or equal to 32 weeks and mean weight 1304 g (range 710 to 1830 g) developed RIS. In most infants the initial apnea occurred after 2 and before 72 hours post delivery but in some infants later. Because of progressive hypoxemia and acidosis 15 of the 26 RIS infants required IPPV treatment. The 76% survival rate of RIS infants seems to justify intensive care with ventilatory support even in the smallest preterm infants with RIS, especially as the follow-up study performed at 15 months to 3-1/2 years of age showed neurological sequelae in only 3 of 20 surviving babies, i.e. 15% sequelae rate.