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OBJECTIVE: To review the clinical use of noninvasive positive pressure ventilation (NPPV) in both acute hypoxic and hypercarbic forms of pediatric respiratory failure, including its mechanism of action and implementation. DATA SOURCES: Studies were identified through a MEDLINE search using respiratory failure, pediatrics, noninvasive ventilation, and mechanical ventilation as key words. STUDY SELECTION: All original studies, including case reports, relating to the use of noninvasive positive pressure in pediatric respiratory failure were included. Because of the paucity of published literature on pediatric NPPV, no study was excluded. DATA EXTRACTION: Study design, numbers and diagnoses of patients, types of noninvasive ventilator, ventilator modes, outcome measures, and complications were extracted and compiled. DATA SYNTHESIS: For acute hypoxic respiratory failure, all the studies reported improvement in oxygenation indices and avoidance of endotracheal intubation. The average duration of NPPV therapy before noticeable clinical improvement was 3 hrs in most studies, and NPPV was applied continuously for 72 hrs before resolution of acute respiratory distress. In patients with acute hypercarbic respiratory failure, application of NPPV resulted in reduction of work of breathing, reduction in CO(2) tension, and increased serum bicarbonate and pH. These patients are older than patients in the acute hypoxic respiratory failure group and, in addition to improved blood gas indices, they reported improvement in subjective symptoms of dyspnea. Improvement in gas exchange abnormalities and subjective symptoms occurred within the same time span (the first 3 hrs) as in the acute hypoxic respiratory failure group. However, use of noninvasive techniques in patients with acute hypercarbic respiratory failure continued after resolution of acute symptoms. Complications related to protracted use of NPPV were common in this group. CONCLUSIONS: NPPV has limited benefits in a group of carefully selected pediatric patients with acute hypoxic and hypercarbic forms of respiratory failure. The routine use of this technique in pediatric respiratory failure needs to be studied in randomized controlled trials and better-defined patient subsets.

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BACKGROUND: The femoral vein is an important site for central venous access in newborns and infants. The objectives of this study are to determine whether age or weight can be used clinically to predict the size of the femoral vein in newborns and infants, and to compare the size of the vein in each individual in both the supine and reverse Trendelenburg positions. RESULTS: Analysis was done in 24 euvolemic individuals, each studied in both the supine and reverse Trendelenburg positions. Twelve of these individuals were newborns and 12 were infants. We used two-factor analysis of variance to explore differences between groups and multiple linear regression analysis to estimate the strength of the relationship between variables. In the infant group, there was a correlation between femoral vein diameter and weight. There was no correlation between weight and vessel size in newborns. In both the newborn and infant groups, vessel diameter increased with subjects in the reverse Trendelenburg position (P < 0.01). CONCLUSION: Weight is predictive of femoral vein diameter in infants, but not in newborns. In infants, weight might serve as a more sensitive index for estimating size of the femoral vein in order to determine accurately the size of intravascular catheter appropriate for cannulation. The diameter of the femoral vein increases in the reverse Trendelenburg position compared with that in the supine position in both newborns and infants. A large prospective study is required to validate these findings.

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STUDY OBJECTIVES: To identify pulmonary risk factors associated with prolonged ICU stay in young children (< or = 2 years) undergoing surgical repair for congenital heart disease (CHD). DESIGN: Retrospective case series analysis. SETTING: Tertiary-care facility. PATIENTS: Clinical records of 134 consecutive patients aged < or = 2 years undergoing cardiac surgery for CHD were reviewed, and 37 were excluded according to inclusion criteria. Thus, 97 patients were allocated to two groups based on the duration of ICU stay: < or = 7 days (group 1, n = 57), and > 7 days (group 2, n = 40). RESULTS: Mean ICU duration for groups 1 and 2 was 3.0 +/- 0.4 days and 28.1 +/- 4.4 days, respectively (p < 0.001). In group 1, there were three extubation failures, whereas 41 extubation failures occurred in group 2 (p < 0.0001). A total of 22 patients (4 in group 1 and 18 in group 2) developed noninfectious pulmonary complications, such as airway problems, including extrinsic airway compression and tracheobronchomalacia (n = 6); pulmonary hypertension (n = 5); phrenic nerve palsy (n = 7); and pleural effusion (n = 8). These 22 patients (23%) contributed to the majority of total ventilator days (67%) as well as ICU stay (61%). CONCLUSIONS: Pulmonary complications in general, and central airway problems in particular, are a frequent cause for delayed recovery following cardiac surgery in young children.

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Subcutaneous emphysema is an unusual complication of bronchiolitis. The investigators describe a patient with bronchiolitis who developed extensive subcutaneous emphysema. Despite an alarming appearance, the patient recovered with symptomatic care and observation. Review of the literature shows a multitude of causes of subcutaneous emphysema. The vast majority of cases resolve without intervention.

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Venous access in the infant and child is always challenging. The hypotensive child who is deteriorating needs rapid volume expansion and medications. Vascular collapse and previous venous cut-downs can preclude easy cannulation of vessels. Intraosseous infusion of fluids and drugs can be readily performed. The technique is easily mastered and there are few complications.

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We describe a neonate with an accessory diaphragm, a rare congenital anomaly. It almost always occurs in the right hemithorax, which appears diffusely hazy on the anterior chest roentgenogram. The lateral chest roentgenogram is essential in the diagnosis of this condition.

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Ribonucleoside and deoxyribonucleoside triphosphate pools have been measured in Escherichia coli infected with bacteriophage T4 DNA polymerase mutator, wild type, and antimutator alleles during mutagenesis by the base analogue 2-aminopurine. ATP and GTP pools expand significantly during mutagenesis, while CTP and UTP pools contract slightly. The DNA polymerase (gene 43) alleles and an rII lesion perturb normal dNTP pools more than does the presence of 2-aminopurine. We find no evidence that 2-aminopurine induces mutations indirectly by causing an imbalance in normal dNTP pools. Rather, it seems likely that, by forming base mispairs with thymine and with cytosine, 2-aminopurine is involved directly in causing bidirectional A.T in equilibrium G.C transitions. The ratios for 2-aminopurine deoxyribonucleoside triphosphate/dATP pools are 5-8% for tsL56 mutator and 1-5% for tsL141 antimutator and 43+ alleles. We conclude that the significant differences observed in the frequencies of induced transition mutations in the three alleles can be attributed primarily to the properties of the DNA polymerases with their associated 3'-exonuclease activities in controlling the frequency of 2-aminopurine.cystosine base mispairs.

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The differential stethoscope is a unique instrument that assists in rapid evaluation of pulmonary problems in the acutely ill patient. Simultaneous auscultation of homologous lung segments eliminates the problem of variability of breathing rate and pattern that must be confronted in conventional auscultation.

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We describe in vitro measurements of heteroduplex base mispaired intermediates involving 5-bromouracil and 2-aminopurine in A X T----G X C and G X C----A X T transition mutation pathways. For the case of 2-aminopurine, 2-aminopurine X cytosine mispairs are formed at a much higher frequency than adenine X cytosine mispairs in either transition pathway. For the case of 5-bromouracil, at least a 40-fold increase in 5-bromouracil X guanine mispairs are observed over thymine X guanine mispairs but only in the G X C----A X T pathway. In the A X T----G X C pathway, mispairs involving 5-bromouracil are formed 2.5-fold more frequently to those involving thymine suggesting perhaps that 5-bromouracil may exhibit substantially different base-pairing behavior depending on whether it is present as a template base or as a deoxyribonucleosides triphosphate substrate. The effect of the base analogs on dNTP pool size perturbations is discussed. A measurement of dNTP pools in 2-aminopurine mutagenized bacteriophage T4-infected cells is presented. An approximate eight-fold expansion in common dNTP pools is observed in a ts L141 antimutator genetic background compared to wild type T4 43+ and ts L56 mutator backgrounds. The effects of distorted dNTP pools on mutagenesis will be considered.

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We present a framework for understanding calculations of continuous infusions of vasoactive substances. Several simplified methods for establishing initial concentrations and infusion rates of drug are derived, their applicability is discussed, and examples are given.

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