Muscle weakness in critically ill children.

OBJECTIVE: To establish the incidence of muscle weakness in critically ill children. METHODS: Neuromuscular examinations were performed in 830 children without identified antecedent or acute neuromuscular disease (age 3 months to 17 years 11 months) admitted for >24 hours to a pediatric intensive care unit (ICU) over a 1-year period. RESULTS: Fourteen of 830 (1.7%) patients had generalized weakness. Four failed repeated attempts to extubate. Multiple organ dysfunction occurred in 11 patients and sepsis in 9. Most children received corticosteroids, neuromuscular blocking agents, or aminoglycoside antibiotics. Eight of the 14 children were solid organ or bone marrow transplant recipients. Muscle biopsy showed evidence of acute quadriplegic myopathy in all three patients in whom biopsy was performed. Three patients died. In survivors, significant weakness persisted for 3 to 12 months following ICU discharge. CONCLUSIONS: Muscle weakness is an infrequent but significant feature of critical illness in children. Transplant recipients seem to be at particular risk.

The role of neutrophil apoptosis in the resolution of acute lung injury in newborn infants.

BACKGROUND: The persistent airway neutrophilia observed in chronic lung disease of prematurity (CLD) may reflect inappropriate suppression of neutrophil apoptosis. METHODS: 134 bronchoalveolar lavage (BAL) samples were obtained from 32 infants requiring mechanical ventilation for respiratory distress syndrome (RDS): 13 infants (median gestation 26 weeks, range 23 to 28) subsequently developed CLD (CLD group), and 19 infants (gestation 31 weeks, range 25 to 39) recovered fully (RDS group). A further 73 BAL samples were obtained from 20 infants (median age 2 days, range 1 to 402) receiving extracorporeal membrane oxygenation (ECMO) for severe respiratory failure. RESULTS: Neutrophil apoptosis was increased in the RDS group (mean (SEM) neutrophil apoptosis on day 7 BAL: RDS 17.0 (8.6)% v CLD 0.7 (0.2)% (p<0.05)). BAL fluid obtained from RDS but not CLD patients was proapoptotic to neutrophils (apoptosis ratio BAL fluid/saline control: day 1, RDS 9.8 (5.5) v CLD 1.2 (0.1) (p<0.05); day 2, RDS 4.32 (2.8) v CLD 0.5 (0.4) (p<0.05)). There were similar findings in the ECMO group: survivors had proapoptotic BAL fluid compared with non-survivors (apoptosis ratio day 1, survivors 7.9 (2.1) v non-survivors 2.1 (0.7) (p<0.05)). CONCLUSIONS: Inappropriate suppression of neutrophil apoptosis may be associated with a poor outcome in newborn infants with respiratory failure.

Repeatability of cellular constituents and cytokine concentration in fluid obtained by non-bronchoscopic bronchoalveolar lavage of infants receiving extracorporeal oxygenation.

BACKGROUND: Since few studies have assessed the repeatability of non-bronchoscopic bronchoalveolar lavage (NB-BAL), we compared cellular counts and cytokine concentrations in fluid obtained by standardised NB-BAL from each side of 20 intubated infants receiving extracorporeal membrane oxygenation (ECMO). METHODS: Total cell counts were obtained from 95 paired lavages and 77 pairs were suitable for differential counts and measurement of cytokine concentrations. RESULTS: Moderate correlation was noted between the two sides for most cell types including total cell counts and percentages of neutrophils and macrophages (R=0.70-0.84) and for cytokine concentrations (IL-8 R=0.78, IL-6 R=0.75, TNF-alpha R=0.64, all p< or =0.001). Using Bland-Altman analysis the mean difference between the two sides approached zero for cellular constituents (total cell counts mean difference 1.7, limits of agreement -187.5 to +190.9 x 10(4)/ml; percentage neutrophils -3.9%, -41.5% to +33.6%; percentage macrophages 3.9%, -33.8% to +41.6%) but tended to be greater on the right for logarithmically transformed cytokine measurements (IL-8: left/right ratio 0.74, limits of agreement 0.12 to 5.45, IL-6: 0.93, 0.09 to 5.87, and TNF-alpha: 0.93, 0.27 to 3.16). Using linear regression with random effects to assess the variability, only the infant's age appeared to influence the cellular results but, for cytokines, only the volume retrieved affected the variability. The magnitude of the measurements, the underlying disease, the operator's experience, days on ECMO, or survival did not affect the variability. CONCLUSION: Measurements obtained by NB-BAL need to be interpreted with caution and strongly suggest that normalisation for the dilutional effects of saline is essential.

Pulmonary atresia, "intact ventricular septum", and aortopulmonary collateral arteries.

In muscular pulmonary atresia, major aortopulmonary collateral arteries are characteristic of pulmonary atresia with ventricular septal defect and are rarely seen in pulmonary atresia with intact ventricular septum. Two unusual cases of muscular pulmonary atresia are reported, one with an intact septum and one with a perimembranous ventricular septal defect, closed in utero by aneurysmal tricuspid tissue. In both cases the pulmonary blood supply came entirely from aortopulmonary collaterals. In case 1 a collateral artery connected the left subclavian artery and hypoplastic pulmonary arteries, and several aortopulmonary collaterals arose from the descending aorta, without overlap between these two circulations. In case 2 the pulmonary trunk and arterial duct were absent and the pulmonary blood supply came entirely from collateral arteries. The right ventricle was of normal size and tripartite with a closed perimembranous ventricular septal defect, discovered only at postmortem examination. These observations suggest right ventricular outflow tract obstruction early in fetal development, with involution of the pulmonary trunk and sixth arch derivatives, and persistence of primitive aortopulmonary connections. The morphology in case 1 is at odds with the theoretical division of pulmonary atresia with intact septum and pulmonary atresia with ventricular septal defect into two separate pathological entities that occur at different stages in fetal development.