Pulmonary sequelae at six months following extracorporeal membrane oxygenation

Follow-up in Neonatal Extracorporeal Membrane Oxygenation (ECMO)

In 34 survivors of the first 43 ECMO patients from our institution before discharge to another hospital or home an EEG, BAER, Head Ultrasonography, cerebral CT scan, Dubowitz score and ophthalmological inspection were performed. At one year of age Mental Developmental Index of the Bayley scales, Motor Quotient as well as pulmonary and neurological status were assessed. In 29 patients follow-up took place in our hospital. In 17 of them (59%) all tests before discharge were normal, 2 patients (7%) showed an abnormal BAER, an additional 5 patients (17%) had abnormal EEG and 2 patients (7%) had abnormal HUS in combination with abnormal cerebral CT scan. In 19 patients (33%) the Dubowitz score was abnormal at discharge. At one year of age neurological status was normal in 25 (86%) patients, respiratory status was normal in 22 (76%) and Mental Development Index was > 80 in 23 of the patients (79%). A significant correlation between Mental Development Index and Motor Quotient was found r=0.50, p=0.0065. It is concluded that more than one abnormal neurophysiological test before discharge may identify patients with additional risks for adverse outcome and that the respiratory status influenced psychomotor development at one year of age.

Long-term outcome of children treated with neonatal extracorporeal membrane oxygenation: increasing problems with increasing age

As more and more critically ill neonates survive, it becomes important to evaluate long-term morbidity. This review aims to provide an up-to-date overview of medical and neurodevelopmental outcomes in children who as neonates received treatment with extracorporeal membrane oxygenation (ECMO). Most patients-except those with congenital diaphragmatic hernia-have normal lung function and normal growth at older age. Maximal exercise capacity is below normal and seems to deteriorate over time in the CDH population. Gross motor function problems have been reported until school age. Although mental development is usually favorable within the first years and cognition is normal at school age, many children experience problems with working speed, spatial ability tasks, and memory. In conclusion, children who survived neonatal treatment with ECMO often encounter neurodevelopmental problems at school age. Long-term follow-up is needed to recognize problems early and to offer appropriate intervention.

Prospective longitudinal evaluation of lung function during the first year of life after extracorporeal membrane oxygenation

OBJECTIVE

To collect longitudinal data on lung function in the first year of life after extracorporeal membrane oxygenation and to evaluate relationships between lung function and perinatal factors. Longitudinal data on lung function in the first year of life after extracorporeal membrane oxygenation are lacking.

DESIGN

Prospective longitudinal cohort study.

SETTING

Outpatient clinic of a tertiary level pediatric hospital.

PATIENTS

The cohort consisted of 64 infants; 33 received extracorporeal membrane oxygenation for meconium aspiration syndrome, 14 for congenital diaphragmatic hernia, four for sepsis, six for persistent pulmonary hypertension of the neonate, and seven for respiratory distress syndrome of infancy. Evaluation was at 6 mos and 12 mos; 39 infants were evaluated at both time points .

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Functional residual capacity and forced expiratory flow at functional residual capacity were measured and expressed as z score. Mean (sem) functional residual capacities in z score were 0.0 (0.2) and 0.2 (0.2) at 6 mos and 12 mos, respectively. Mean (sem) forced expiratory flow was significantly below average (z score = 0) (p < .001) at 6 mos and 12 mos: -1.1 (0.1) and -1.2 (0.1), respectively. At 12 mos, infants with diaphragmatic hernia had a functional residual capacity significantly above normal: mean (sem) z score = 1.2 (0.5).

CONCLUSIONS

Infants treated with extracorporeal membrane oxygenation have normal lung volumes and stable forced expiratory flows within normal range, although below average, within the first year of life. There is reason to believe, therefore, that extracorporeal membrane oxygenation either ameliorates the harmful effects of mechanical ventilation or somehow preserves lung function in the very ill neonate.

Clinical correlations and pulmonary function at 8 years of age after severe neonatal respiratory failure

OBJECTIVES

The aim of this study was to determine the pulmonary sequelae of severe neonatal respiratory failure.

STUDY DESIGN

This was a multicenter, prospective study. Fifty-four survivors of neonatal respiratory failure (oxygenation indices >25 on two occasions), completed pulmonary function testing at 8 years of age. Thirty-one (57%) received extracorporeal membrane oxygenation (ECMO). Pulmonary outcome was based on spirometry and lung volume data. Pulmonary outcome for each diagnostic and treatment group is reported as mean and as percent predicted. Individually subjects were also classified based on spirometry, as either normal, obstructed (defined as forced expiratory volume (FEV(1)) in 1 sec:forced vital capacity (FVC) of <80 % predicted, or with reduced FVC (FCV of <80% predicted) with normal FEV(1)/FVC. Risk for adverse outcome was determined using univariate analysis.

RESULTS

Mean FVC, FEV(1) and FEV(25-75) were reduced in the total cohort. The reduction was greatest in the subgroup with CDH and the group treated with ECMO. Assessed individually, 54% of subjects had normal spirometry and lung volumes, 19% airflow obstruction, and 27% reduced FVC. Poorer pulmonary outcome was linked to ECMO, congenital diaphragmatic hernia (CDH), birth weight for gestational age <10th percentile, duration of hospitalization, or need for prolonged supplemental oxygen.

CONCLUSION

Neonates with severe respiratory failure due to CDH or needing ECMO and small for gestation are at increased risk of poorer pulmonary outcome and require close follow-up.

Porcine pulmonary artery and bronchial responses to endothelin-1 and norepinephrine on recovery from hypoxic pulmonary hypertension

Many infants recovering from acute lung disease and pulmonary hypertension still have evidence of reactive airways disease at one year of age, suggesting longer-term airway effects. We hypothesized that parallel changes in smooth muscle would occur in airways and pulmonary arteries from animals with pulmonary hypertension and during normoxic recovery. Thus, two-hour-old piglets were subjected to 3 d chronic hypobaric hypoxia and 3-d-old piglets were subjected to 11 d hypoxia. Some animals were allowed to recover in room air for 3 or 6 d. The amount of smooth muscle and responses of isolated paired bronchial and pulmonary artery rings to endothelin-1 (ET-1) and norepinephrine were studied at the end of hypoxic exposure, on recovery and in age-matched control animals. In all hypoxia induced pulmonary hypertensive animals, smooth muscle area and ET-1 contractile response was increased in the pulmonary arteries and bronchi. Norepinephrine-induced relaxant response was impaired significantly in both bronchi and pulmonary arteries. After 3 d recovery, pulmonary arterial smooth muscle area decreased by 65%, and ET-1-induced contractile responses were normal for age. In the airways, ET-1 contractile response only normalized after six days and bronchial smooth muscle was still increased. After 6 d recovery pulmonary arterial norepinephrine-induced relaxant response had returned to normal, but bronchial response remained impaired. Thus during pulmonary hypertension, both bronchial and pulmonary arterial smooth muscle area and contractile responses are increased. On recovery, regression of bronchial structural and functional abnormalities is slower than in pulmonary arteries.

Lung function tests in neonates and infants with chronic lung disease of infancy: functional residual capacity

This is the second paper in a review series that will summarize available data and discuss the potential role of lung function testing in infants and young children with acute neonatal respiratory disorders and chronic lung disease of infancy. The current paper addresses the expansive subject of measurements of lung volume using plethysmography and gas dilution/washout techniques. Following orientation of the reader to the subject area, we focus our comments on areas of inquiry proposed in the introductory paper to this series. The quality of the published literature is reviewed critically, and recommendations are provided to guide future investigation in this field. Measurements of lung volume are important both for assessing growth and development of lungs in health and disease, and for interpreting volume-dependent lung function parameters such as respiratory compliance, resistance, forced expiratory flows, and indices of gas-mixing efficiency. Acute neonatal lung disease is characterized by severely reduced functional residual capacity (FRC), with treatments aimed at securing optimal lung recruitment. While FRC may remain reduced in established chronic lung disease of infancy, more commonly it becomes normalized or even elevated due to hyperinflation, with or without gas-trapping, secondary to airway obstruction. Ideally, accurate and reliable bedside measurements of FRC would be feasible from birth, throughout all phases of postnatal care (including assisted ventilation), and during subsequent long-term follow-up. Although lung volume measurements in extremely preterm infants were described in a research environment, resolution of several issues is required before such investigations can be translated into routine clinical monitoring.

Long-term pulmonary sequelae in children who were treated with extracorporeal membrane oxygenation for neonatal respiratory failure

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for neonates with intractable respiratory failure, but the long-term pulmonary outcome is unknown. Our aim was to investigate the long-term pulmonary sequelae of these children.

STUDY DESIGN

We studied 50 children at 11.1 +/- 1.1 years (mean +/- SD) who had been treated with neonatal ECMO for meconium aspiration syndrome (38%), sepsis (18%), sepsis with pneumonia (12%), congenital diaphragmatic hernia (12%), congenital heart disease (8%), persistent pulmonary hypertension of the newborn (6%), and respiratory distress syndrome (4%) and 27 healthy controls (10.8 +/- 1.6 years). All subjects completed a respiratory questionnaire and performed pulmonary function and graded cardiopulmonary exercise testing.

RESULTS

Neonatal ECMO survivors had hyperinflation (median residual volume: 131%), airway obstruction (median forced expired volume in 1 second: 79%), lower oxygen saturation with exercise, and lower peak oxygen consumption than controls. The ECMO group achieved similar exercise minute ventilation to controls, with more rapid and shallow breathing. ECMO survivors had an increased frequency of exercise-induced bronchospasm. Those who required higher inspired oxygen tension and ventilator pressures after weaning from ECMO had lower forced expired volume in 1 second and oxygen saturation values.

CONCLUSION

Neonatal ECMO survivors experience lung injury lasting into later childhood. Lung dysfunction correlates with the extent and duration of barotrauma and oxygen exposure as neonates.

Maturation of peripheral arterial chemoreceptors in relation to neonatal apnoea

Apnoea and periodic breathing are the hallmarks of breathing for the infant who is born prematurely. Sustained respiration is obtained through modulation of respiratory-related neurons with inputs from the periphery. The peripheral arterial chemoreceptors, uniquely and reflexly change ventilation in response to changes in oxygen tension. The chemoreflex in response to hypoxia is hyperventilation, bradycardia and vasoconstriction. The fast response time of the peripheral arterial chemoreceptors to changes in oxygen and carbon dioxide tension increases the risk of more periodicity in the breathing pattern. As a result of baseline hypoxaemia, peripheral arterial chemoreceptors contribute more to baseline breathing in premature than in term infants. While premature infants may have an augmented chemoreflex, infants who develop bronchopulmonary dysplasia have a blunted chemoreflex at term gestation. The development of chemosensitivity of the peripheral arterial chemoreceptors and environmental factors that might cause maldevelopment of chemosensitivity with continued maturation are reviewed in an attempt to help explain the physiology of apnoea of prematurity and the increased incidence of sudden infant death syndrome (SIDS) in infants born prematurely and those who are exposed to tobacco smoke.

Cardiopulmonary outcome of neonatal extracorporeal membrane oxygenation at ages 10–15 years

OBJECTIVE

The purpose of this study was to evaluate the long-term cardiopulmonary outcome at ages 10-15 yrs following neonatal extracorporeal membrane oxygenation (ECMO). The specific aims of the study were to assess baseline aerobic capacity, cardiac function, and pulmonary function in neonatal ECMO survivors using graded exercise testing, echocardiography, and pulmonary function tests.

DESIGN

Cohort study.

SETTING

Exercise and pulmonary function laboratories of a large children's hospital.

PATIENTS

Seventeen 10- to 15-yr-old children treated with ECMO as neonates for meconium aspiration syndrome and 17 age-matched healthy controls.

INTERVENTIONS

Children were evaluated by use of physical exam, electrocardiogram, echocardiogram, treadmill stress test, and pulmonary function tests.

MEASUREMENTS AND MAIN RESULTS

Average weight, height, and age were similar between the groups. Both pre- and postexercise pulmonary function tests revealed air trapping and mild lower airway obstruction in the ECMO group, compared with mean pulmonary functions in the normal range for the control group. The mean forced expiratory volume in 1 sec, the forced expiratory flow between 25% and 75% of vital capacity, and the ratio between residual volume and total lung capacity were significantly different between the ECMO group and the control group. Although the ECMO group exhibited baseline and postexercise lung function abnormalities, there were no differences in maximal oxygen consumption between the two groups and all subjects reached anaerobic threshold. By regression analysis, the gestational age, duration of oxygen, and exercise score were significantly correlated with baseline lung function, using forced expiratory flow between 25% and 75% of vital capacity as the dependent variable.

CONCLUSIONS

Despite abnormalities in baseline and postexercise pulmonary functions, ECMO graduates have similar aerobic capacity to age-matched healthy controls. The most significant factor in predicting long-term pulmonary outcome in ECMO graduates is the duration of oxygen use following decannulation.

Respiratory function in survivors of the United Kingdom Extracorporeal Membrane Oxygenation Trial

Extracorporeal membrane oxygenation (ECMO) improves survival in mature neonates with reversible lung disease. However, ECMO could result in survival of infants with severe respiratory dysfunction who would otherwise have died. Alternatively, infants receiving ECMO might be spared prolonged ventilation and consequent barotrauma, resulting in improved respiratory function. Our aim was to compare respiratory function at 1 yr of age in infants assigned to receive either ECMO or conventional management (CM). Seventy-eight surviving infants of the United Kingdom (UK) ECMO trial (51 in the ECMO group) were studied at 1 yr of age. Questionnaires provided details of respiratory symptoms, and laboratory measurements of respiratory function were made for respiratory rate, tidal volume, lung volume, airway conductance, specific airway conductance, and maximal expiratory flow at FRC (Vmax (FRC)). Data were exchanged on floppy disk for cross-analysis and to ensure that investigators were blinded to the status of the infants. There was a wide spectrum of respiratory function, from normal to markedly abnormal. There were few differences between the groups, but in the CM group lung volume was increased (95% confidence intervals [CIs] of the difference in ECMO versus CM subjects: -67; -4 ml), and inspiratory specific conductance was lower (95% CI: 0.03; 0.98 s(-)(1). kPa(-)(1)). There was a trend toward a lower V max(FRC) (95% CI: -2; 67 ml/s(-)(1) in the CM group. In addition to providing a survival advantage, ECMO did not worsen lung function in infants assigned to receive it. Indeed, their lung function appeared slightly better than that of infants treated conventionally.

[Clinical and respiratory function follow-up of 39 infants treated with neonatal respiratory extracorporeal assistance]

The aim of this prospective study was to evaluate the consequences of neonatal treatment with a venovenous extracorporeal respiratory assistance.

POPULATION AND METHODS

Thirty nine neonates (28 boys) with acute respiratory failure were included. Extracorporeal respiratory assistance consisted of an apnoeic oxygenation with low frequency positive pressure ventilation and extracorporeal membrane CO2 removal through a venous single canula perfusion circuit. The causes of respiratory distress were: 15 meconium aspiration syndrome, 12 respiratory distress syndrome, six hyaline membrane disease, three sepsis, two diaphragmatic hernia, and one post-surgery Mendelson syndrome. The mean duration of mechanical ventilation was 18 days, including 5 days of extracorporeal respiratory assistance. The prospective follow-up included physical examination, chest radiographs, scintigraphy and pulmonary function tests. These tests studied the following parameters: functional residual capacity by helium dilution technique, lung resistance and dynamic lung compliance by the esophageal balloon technique and blood gases with arterialized blood samples.

RESULTS

The mean duration of the follow-up was 21.3 months (6 months to 5 years). Results showed in the first year 33% of children with chronic obstructive pulmonary disease and chest (X-ray abnormalities, such as bronchopulmonary dysplasia in 23% of children. Data of pulmonary function test at the end of the first year: lung resistance and functional residual capacity were within limits of predicted values for height, and dynamic lung compliance was slightly decreased; according to the analysis of the functional profile: 31% without abnormality, 41% of obstructive syndrome and 26% with restrictive pattern. Blood gases were normal in 37 children. At the end of the second year, we noticed normal functional residual capacity, an increase of lung resistance while lung compliance was normalized; functional profile was quite different: with a decrease of the number of patients without abnormality (22%) and increase of those with obstructive syndrome (56%).

CONCLUSION

The percentage of abnormalities is high but these are moderate in most cases, especially if we compare with the initial seriousness of the pulmonary pathology. We suggest a regular follow-up to study the respective incidence of pulmonary disease and/or extracorporeal respiratory assistance over these abnormalities.

Pulmonary sequelae in infants treated with extracorporeal membrane oxygenation

The decision to place an infant on extracorporeal membrane oxygenation (ECMO) is based on predictions of expected morbidity and mortality. One unknown factor is the relationship between pre-ECMO pulmonary dysfunction and on barotrauma and post-ECMO pulmonary sequelae. To determine whether placement of infants on extracorporeal membrane oxygenation (ECMO) early is associated with less subsequent pulmonary dysfunction than placing infants on EMCO later, we evaluated pulmonary function in 25 neonates prior to ECMO, when the infants had come off EMCO, and at the time of nursery discharge. Pulmonary resistance (R) and compliance (CL) were determined by a pneumotachograph and esophageal manometry, and functional residual capacity (FRC) was determined by a helium dilution method. Maximal expiratory flow (VmaxFRC) was determined by thoracic compression at the time of discharge. Infants were assigned to an early ECMO group (< 36 hours of age, n = 12), or a late ECMO group (> 36 hours of age, n = 13). When first evaluated, the early group had a higher oxygenation index than the late group (mean value, 63 versus 48), but initial pulmonary function measurements were not different between the two groups. In the early group mean CL increase from 0.20 to 0.36 ml/cmH2O/kg, FRC increased from 7 to 20 ml/kg, and mean R decreased from 107 to 61 cmH2O/L/sec between the initial study and immediately after ECMO. In the late group, only FRC increased from a mean of 8 to 20 ml/kg. CL and FRC increased from post-ECMO to discharge in both groups (mean CL from 0.36 to 0.76 ml/cmH2O/kg in the early group, and from 0.30 to 0.79 in the late group). Mean FRC increased from 20 to 26 ml/kg in the early group, and from 20 to 25 ml/kg in the late group. VmaxFRC was lower in the late than the early group at discharge (mean, 1.14 versus 1.58 L/sec; P < 0.05). While both groups of infants had minimal pulmonary dysfunction at discharge, the infants placed on ECMO early had evidence of slightly less airway dysfunction despite a higher initial oxygenation index than the infants placed on ECMO late.

Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation has now evolved into standard therapy for patients unresponsive to conventional ventilatory and pharmacological support. This article presents a clinical review of extracorporeal life support and its application to neonatal and pediatric patients as well as children requiring circulatory support after open heart surgery.

Neonatal meconium aspiration syndrome and respiratory morbidity during infancy

Respiratory morbidity in the first 6 months of life of 35 infants who had had neonatal meconium aspiration syndrome (MAS) was compared to that of 70 controls, also born at term, matched for gender and ethnic origin. The number of infants in the two groups who were symptomatic was compared. Infants were described as symptomatic if, following discharge from hospital, they had at least one episode of wheezing and/or coughing which lasted for 3 days or more. There was no significant difference between the two groups regarding parental smoking or the proportion of infants who had a family history of atopy. A significantly greater proportion of the MAS group (49%) than of the control group (20%) was symptomatic at follow-up. Eight (23%) infants with MAS and 2 (3%) controls had symptoms which necessitated regular bronchodilator therapy. The 8 infants with MAS who were on maintenance bronchodilator therapy had required significantly longer neonatal respiratory support and had larger lung volumes at follow-up than the other 27 infants. We conclude that neonatal meconium aspiration syndrome is associated with increased respiratory morbidity in the first 6 months of life.