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.

Population pharmacokinetics of midazolam and its metabolites during venoarterial extracorporeal membrane oxygenation in neonates.

BACKGROUND AND OBJECTIVE: Midazolam is used to sedate children during extracorporeal membrane oxygenation (ECMO). Pharmacokinetic changes are expected because of extracorporeal circulation and maturation. We present a population pharmacokinetic model for midazolam and its major metabolites in neonates during venoarterial ECMO. METHODS: We studied 20 neonates on venoarterial ECMO, with a median postnatal age of 0.79 (range 0.17-5.8) days and a bodyweight of 3.0 (range 2.7-3.9) kg at the onset of ECMO. The median ECMO duration was 124 (range 70-275) hours. Serum concentrations were measured at the initiation and discontinuation of the midazolam infusion (100-300 microg/kg/h). Analysis of concentrations of midazolam, 1-hydroxymidazolam and its glucuronide were performed using nonlinear mixed-effects modelling. A two-compartment model for midazolam and a one-compartment model for the metabolites 1-hydroxymidazolam and hydroxymidazolam glucuronide adequately described the data, with allometric scaling of all parameters. RESULTS: Following the start of ECMO, the volume of distribution of midazolam increased from 4.29 to 14.6 L/3 kg, with an elimination half-life of 1.85 hours. The median midazolam and 1-hydroxymidazolam clearance values increased 3-fold within the first 5 days (up to 1.38 and 5.31 L/h/3 kg, respectively), whereas hydroxymidazolam glucuronide clearance remained constant at 0.18 L/h/3 kg. Interpatient variability estimates of midazolam, 1-hydroxymidazolam and hydroxymidazolam glucuronide clearance and midazolam and hydroxymidazolam glucuronide volumes of distribution varied between 87% and 129%. Concomitant inotropic infusion increased hydroxymidazolam glucuronide clearance by 23%. CONCLUSION: After allometric scaling, clearance of midazolam and 1-hydroxymidazolam increases as a result of maturation or recovery from critical illness. In ECMO patients weighing 2.7-3.9 kg, continuously infused midazolam doses of 300 microg/kg/h for 6 hours and 150 microg/kg/h thereafter provide adequate serum concentrations for sedation. The dose must be increased substantially after 5-7 days. Hydroxymidazolam glucuronide accumulates during ECMO, providing an increased proportion of the overall effect, up to 34% after 7 days. Large unexplained interpatient variability warrants careful titration of sedation and adverse effects.

Follow-up of newborns treated with extracorporeal membrane oxygenation: a nationwide evaluation at 5 years of age.

INTRODUCTION: Extracorporeal membrane oxygenation (ECMO) is a supportive cardiopulmonary bypass technique for babies with acute reversible cardiorespiratory failure. We assessed morbidity in ECMO survivors at the age of five years, when they start primary school and major decisions for their school careers must be made. METHODS: Five-year-old neonatal venoarterial-ECMO survivors from the two designated ECMO centres in The Netherlands (Erasmus MC--Sophia Children's Hospital in Rotterdam, and University Medical Center Nijmegen) were assessed within the framework of an extensive follow-up programme. The protocol included medical assessment, neuromotor assessment, and psychological assessment by means of parent and teacher questionnaires. RESULTS: Seventeen of the 98 children included in the analysis (17%) were found to have neurological deficits. Six of those 17 (6% of the total) showed major disability. Two of those six children had a chromosomal abnormality. Three were mentally retarded and profoundly impaired. The sixth child had a right-sided hemiplegia. These six children did not undergo neuromotor assessment. Twenty-four of the remaining 92 children (26%) showed motor difficulties: 15% actually had a motor problem and 11% were at risk for this. Cognitive delay was identified in 11 children (14%). The mean IQ score was within the normal range (IQ = 100.5). CONCLUSION: Neonatal ECMO in The Netherlands was found to be associated with considerable morbidity at five years of age. It appeared feasible to have as many as 87% of survivors participate in follow-up assessment, due to cooperation between two centres and small travelling distances. Objective evaluation of the long-term morbidity associated with the application of this highly invasive technology in the immediate neonatal period requires an interdisciplinary follow-up programme with nationwide consensus on timing and actual testing protocol.

Routine enteral nutrition in neonates on extracorporeal membrane oxygenation.

OBJECTIVES: To evaluate over a 5-yr period the feasibility and tolerance of a protocol of routine enteral nutrition in neonates requiring extracorporeal membrane oxygenation (ECMO). DESIGN: Retrospective medical chart review. SETTING: Level III children's hospital, pediatric surgical intensive care unit. PATIENTS: Neonates treated with venoarterial ECMO (VA-ECMO) between January 1997 and January 2002. Patients with congenital diaphragmatic hernia were excluded. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Charts of all neonates treated with VA-ECMO were reviewed. Feasibility was evaluated by recording the time period needed for enteral nutrition to reach 40% of total fluid intake; tolerance was evaluated by reviewing data on enteral nutrition related morbidity. Sixty-seven of the 77 eligible patients received enteral feeding during ECMO. Thirty-six of these patients (54%) received 40% of total fluid intake as enteral nutrition within a median of 3 (range, 2-4) days. Over the years there was a trend toward an increasing usage of enteral nutrition from 71% to 94% (p = .07). Enteral nutrition was temporarily discontinued in 16 patients, with 14 showing gastric retentions, one showing discomfort, and one showing aspiration. Symptoms of bilious vomiting, blood-stained stool, or abdominal distention were not present. CONCLUSION: Neonates on ECMO in this series tolerated enteral feeding well and did not show serious adverse effects. Overall, it is our experience that routine use of enteral feeding in critically ill neonates on VA-ECMO is feasible.