Magnetic resonance imaging of the upper airway structure of children with obstructive sleep apnea syndrome.

The anatomical relationships between lymphoid, bony, and other tissues affecting the shape of the upper airway in children with obstructive sleep apnea syndrome (OSAS) have not been established. We therefore compared the upper airway structure in 18 young children with OSAS (age 4.8 +/- 2.1 yr; 12 males and 6 females) and an apnea index of 4.3 +/- 3.9, with 18 matched control subjects (age, 4.9 +/- 2.0 yr; 12 males and 6 females). All subjects underwent magnetic resonance imaging under sedation. Axial and sagittal T1- and T2-weighted sequences were obtained. Images were analyzed with image-processing software to obtain linear, area, and volumetric measurements of the upper airway and the tissues comprising the airway. The volume of the upper airway was smaller in subjects with OSAS in comparison with control subjects (1.5 +/- 0.8 versus 2.5 +/- 1.2 cm(3); p < 0.005) and the adenoid and tonsils were larger (9.9 +/- 3.9 and 9.1 +/- 2.9 cm(3) versus 6.4 +/- 2.3 and 5.8 +/- 2.2 cm(3); p < 0.005 and p < 0.0005, respectively). Volumes of the mandible and tongue were similar in both groups; however, the soft palate was larger in subjects with OSAS (3.5 +/- 1.1 versus 2.7 +/- 1.2 cm(3); p < 0.05). We conclude that in children with moderate OSAS, the upper airway is restricted both by the adenoid and tonsils; however, the soft palate is also larger in this group, adding further restriction.

The impact of adverse patient occurrences on hospital costs in the pediatric intensive care unit.

OBJECTIVES: To study the influence of adverse patient occurrences defined as airway complication (AC), vascular complication (VC), and infectious complication (IC) on intensive care unit (ICU) costs and length of stay (LOS). DESIGN: Retrospective, cohort study SETTING: An urban, tertiary care children's hospital in Philadelphia, PA. PATIENTS: All children admitted to a multidisciplinary pediatric ICU during the fiscal year 1994. INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Demographic data, diagnoses, Pediatric Risk of Mortality scores, LOS, and deaths were recorded. Hospital charges were converted into costs by using cost-to-charge ratios. There were 23 AC, 35 VC, and 40 IC events. Multiple regression in models adjusting for age, Pediatric Risk of Mortality score, mortality, chronic disease, and diagnosis by using AC, VC, and IC indicator variables was performed on the dependent variables of LOS and total costs. IC was associated with an increase in total costs of $50,361.89 (p < .001), an increased LOS of 15.6 days (p < .001), and no significant increase in daily costs. There were no significant increases in costs or LOS seen with the AC and VC variables. In a matched analysis, the total costs attributable to IC averaged $32,040 per patient. CONCLUSIONS: The occurrence of complications in the pediatric ICU is associated with meaningful increases in LOS and hospital costs. ICs are more important predictors of costs than ACs or VCs. Continuing efforts should be made to minimize adverse occurrences to improve patient care and reduce costs.

Water and electrolyte metabolism of the micropremie.

There are five problem schemas presented in this article that indicate potential contradictions in therapeutic goals: (1) shock and edema presenting upon premature birth; (2) the hyperosmolar state, problematic in patients less than 750 g birth weight; (3) the respiratory distress syndrome and respiratory failure, often complicated by patent ductus arteriosus; (4) bronchopulmonary dysplasia, resulting from prematurity and mechanical ventilation; and (5) late onset of hyponatremia, sometimes accompanied by growth failure in the recovering premature. These five problems considered together comprise a developmental continuum of illness and recovery, where appropriate fluid management has recently been demonstrated to benefit outcomes greatly. Clinicians over the past decade have encountered all of the fluid and electrolyte nightmares. Although there are many different formulations for treating each of these scenarios, recommending one approach for all patients is likely to be incorrect much of the time.

Hospital costs of pediatric intensive care.

OBJECTIVE: To characterize hospital costs of pediatric intensive care and to determine which demographic and disease characteristics are associated with cost. DESIGN: Prospective cohort study. SETTING: A 20-bed pediatric intensive care unit (PICU) in an urban university-affiliated teaching children's hospital. PATIENTS: All children (n = 1,376) admitted to the multidisciplinary PICU during the fiscal year 1994. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographics, diagnoses, organ failure, Pediatric Risk of Mortality score, length of stay (LOS), and outcome were recorded. All hospital charges were obtained. The actual hospital costs were calculated by two separate methods. First, we converted the itemized patient charges into costs, using corresponding cost-to-charge ratios for each charge. In addition, we examined all direct and indirect expenses for the PICU. Univariate and multivariate regression analyses were used to determine the correlates to cost. The study population was similar to that of other studies of pediatric intensive care. The PICU was 86% efficient. The total cost for PICU care was $16,983,323. Average cost per admission was $12,342 +/- $22,313, and average cost per patient day was $2,264 +/- $868. The cost because of the PICU location (room cost) was 52.1% of all costs, and cost of laboratory studies was 18.3%. Respiratory therapy, pharmacy services, and radiology each accounted for between 6% and 8%. Total cost was most closely related to LOS, but severity of illness (Pediatric Risk of Mortality), diagnosis, and organ failure were also significant. Severity of illness was the most important factor in determining the variation in daily costs. Increased severity of illness was associated with higher laboratory and diagnostic study costs. We found little difference in the PICU room cost when calculated by adding direct and indirect expenses, compared with that obtained by using the cost-to-charge ratio. CONCLUSIONS: The maintenance of the specialty location and its personnel is the most costly component of pediatric intensive care. The strongest correlate with total cost for pediatric intensive care is LOS, but if costs are normalized for LOS, severity of illness best explains cost variation among patients. These data may serve as the basis for additional studies of resource allocation and consumption in the future.

The potential benefits of the pediatric nonheartbeating organ donor.

OBJECTIVE: To examine the population of the pediatric intensive care unit in a large children's hospital to determine the potential importance of pediatric nonheartbeating organ donors (NHBDs). STUDY DESIGN: We analyzed retrospectively the 6307 admissions to the pediatric intensive care unit at the Children's Hospital of Philadelphia from January 1992 to July 1996 to identify all deaths. The hospital records of the children who had died were then reviewed to determine the mode of death, organ donation rate of heartbeating donors, and the number of potential NHBDs. Criteria for the NHBD included the decision to forgo life-sustaining therapy, death occurring within 2 hours of withdrawal of life support, and the absence of sepsis, HIV, hepatitis, or extracranial malignancy. RESULTS: Of 319 deaths, 102 (32.0%) died with resuscitation, 84 (26.3%) were brain-dead, 111 (34.8%) had withdrawal of life support, and 22 (6.9%) were on do-not-resuscitate orders. Of the 84 brain-dead children, 74 (88.1%) were medically suitable heartbeating donors, and 43 (58.1%) donated organs. Of the 111 patients who had life support withdrawn, 31 (27.9%) qualified for NHBDs. CONCLUSIONS: The routine use of the NHBD has the potential to increase organ donation at our institution by 42%. We discuss the ethical issues relating to NHBDs required to properly include these patients as potential organ donors.

Residents on the transport team. Balancing service and education.

OBJECTIVES: To describe an educational program for pediatric house staff who participate in interhospital transport and to present an evaluation of the educational program. DESIGN: Educational program evaluation that used multiple confidential surveys of participating pediatric house staff. SETTING: The interhospital transport team of a large, urban pediatric hospital. PARTICIPANTS: Twenty-six pediatric second-year residents who participated in required rotations with the transport service. INTERVENTION: The institution of an educational program designed specifically for the clinical transport rotation. RESULTS: Before their service with the transport team, residents have doubts about their clinical skills, fund of knowledge, and ability to practice independently in a mobile environment. These doubts decrease as the residents participate in the educational program during their transport clinical service. All residents perceive service on the transport rotation to be of educational benefit with regard to communications or cognitive skills. Alternatively, transport service provides little opportunity for residents to improve technical skills. Among the various skills that residents could obtain during transport service, improvement in clinical judgement was most commonly cited by residents who performed more than 10 transports. Among the specific curricular components in the educational program, interactive teaching methods were judged to be more valuable than written materials. CONCLUSIONS: Serving as a physician on interhospital transports can be an important educational opportunity for pediatric house staff when that experience is concentrated in a designated rotation and combined with a focused educational program. Contrary to expectations, there was little opportunity for residents to develop technical skills on transport. Therefore, educators should focus on the development of communications and cognitive skills. Interhospital transport programs that debate the use of residents as members of the service should consider the potential educational benefit of the clinical service to house staff.

Nasal mask positive pressure ventilation in paediatric patients with type II respiratory failure.

We report our experience with nasal mask ventilation in children and adolescents with type II respiratory failure admitted to the paediatric intensive care unit (PICU) over an 18-month period. Seven patients were treated with nasal mask ventilation during part of their PICU stay. All showed significant improvement in arterial pH, PaCO2, and PaO2/FiO2 from presentation to discharge, although at discharge PaCO2 and PaO2/FiO2 fell outside of the normal range. Complications occurred in four patients. When compared to 11 patients with type II respiratory failure not treated with nasal mask ventilation, the nasal mask ventilation group had a similar PICU length of stay and incidence of complications. We conclude that nasal mask ventilation may be useful in maintaining near normal alveolar ventilation in selected children with type II respiratory failure and that a prospective study of this technique is indicated.

Recognition and management of the ill child.

Children account for 30% of visits to emergency departments, and approximately 5% of these children have serious illness requiring immediate intervention. Over the past decades, as medical knowledge and application have eradicated many illness and rendered others curable, trauma has emerged as the leading cause of morbidity and mortality after the first year of life. However, all children remain vulnerable to infection and its consequences in the first year and beyond the first year. Additionally, over this time span, there are more children with chronic complicated health problems who survive yet remain dependent on sophisticated medical care. Intuitively, prompt recognition of the very ill child and the execution of the immediate and necessary interventions may be life saving. The ability to accomplish this requires a knowledge of the common culprits resulting in serious illness, an understanding of how they manifest in the physical examination, and an array of technical skills utilizing appropriate specially sized equipment. Furthermore, an understanding of child development and the ability to interpret the physical examination of the children of different ages is essential. This article will attempt to simplify this seemingly overwhelming task by considering a common thread in all critical illness.

Cytokine elevations in infants with bacterial and aseptic meningitis.

We sought to determine whether the detection of cytokines, produced during the inflammatory response, would aid in the diagnosis of meningitis in young infants. We measured cerebrospinal fluid (CSF) and plasma levels of interleukin-6 (IL-6) and tumor necrosis factor (TNF) in 62 infants less than 6 months of age whose condition was evaluated for meningitis. Twenty infants had culture-proved meningitis, 22 had aseptic meningitis, and 20 control infants had no evidence of meningitis. The CSF IL-6 levels were elevated in all 20 infants with bacterial meningitis and in 9 of 22 infants with aseptic meningitis but were undetectable in all control subjects. Furthermore, CSF IL-6 levels were 10 times greater in infants with bacterial versus aseptic meningitis (p < 0.001). Levels of TNF in CSF were detected in 12 of 20 infants with bacterial meningitis and were undetectable in infants with aseptic meningitis and in control infants (p < 0.02). Plasma IL-6 and TNF levels were unreliable for the detection of meningitis in this patient population. We conclude that the presence of IL-6 in the CSF reliably identifies infants with meningitis and that the presence of CSF TNF is a highly specific indicator of bacterial meningeal inflammation.

The dose-response relationship for hypoxic pulmonary vasoconstriction.

In 12 pentobarbital anesthetized dogs the lungs were independently ventilated with a double piston ventilator. The right lung was ventilated throughout with 100% oxygen. Blood was drawn from the right atrium and pumped through a bubble oxygenator to a cannula in the ligated left main pulmonary artery. The pressures in the left main pulmonary artery and the left atrium were recorded during constant flow while the oxygen tension in the left lung alveolar gas and the perfusate were varied either to match each other (Protocol 1) or differ (Protocol 2) over the range from "zero" to "100%" oxygen. From the combined data a three dimensional response surface for hypoxic pulmonary vasoconstriction was derived. The maximum increase of pulmonary vascular resistance (r%PVRmax) was defined at a stimulus oxygen tension (PSO2) of 10 mmHg amounting to a 3.15 +/- (0.18)-fold increase of the vascular resistance on "100%" oxygen. The stimulus oxygen tension was shown to be PSO2 = PVO2(0.41) x PAO2(0.59) and the dose-response sigmoid for hypoxic pulmonary vasoconstriction in canine lungs was derived as r%PVRmax = 100 (PSO2(-2.616))/(6.683 x 10(-5) + PSO2(-2.616)) These results appear to reconcile observations from a number of laboratories and to be of quite general application.

Cytokine elevations in critically ill infants with sepsis and necrotizing enterocolitis.

We hypothesized that plasma levels of cytokines such as interleukin-6 and tumor necrosis factor (TNF) are elevated in critically ill infants with sepsis and necrotizing enterocolitis (NEC) and that the magnitude of their elevation is correlated with mortality rate. We measured plasma levels of interleukin-6 and TNF in 62 newborn infants with suspected sepsis or NEC. Eighteen infants had bacterial sepsis, 9 had bacterial sepsis plus NEC, and 15 had NEC but negative culture results. Twenty comparably ill infants with negative results on culture of systemic specimens served as study control subjects. Interleukin-6 levels were five- to tenfold higher in infants with bacterial sepsis plus NEC at the onset of disease than in infants with bacterial sepsis alone, in infants with NEC but negative culture results, and in control infants (p < 0.01). These differences persisted throughout the 48-hour study period. Interleukin-6 levels were also significantly higher in nonsurvivors than in survivors (p < 0.001). In contrast, plasma TNF values were not consistently increased in any of the groups. We conclude that plasma interleukin-6 is a more reliable indicator of bacterial sepsis and NEC than plasma TNF and may identify infants who might benefit from immunotherapeutic strategies.

Adult respiratory distress syndrome in children: associated disease, clinical course, and predictors of death.

The adult respiratory distress syndrome is a common cause of respiratory failure; however, its incidence, risk factors, course, and mortality rate for children remain incompletely understood. A 24-month surveillance of pediatric intensive care admissions identified 60 children with adult respiratory distress syndrome constituting 2.7% of such admissions, 8% of total days spent in a pediatric intensive care unit, and 33% of deaths. The mortality rate was 62% (confidence interval, 48.2% to 73.9%). Adult respiratory distress syndrome occurred in approximately 12% of children admitted for sepsis, viral pneumonia, smoke inhalation, or drowning. A low incidence (< 3%) was observed in children admitted with pulmonary contusion or multiple trauma. Ongoing changes in measures of pulmonary gas exchange varied with the magnitude of alveolar injury; no differences were associated with the underlying acute disease or lung injury mechanism. Efficiency of oxygenation differed among outcome groups by the second day after onset of adult respiratory distress syndrome. An alveolar-arterial oxygen tension difference > 420 was the best early predictor of death (sensitivity 80%, specificity 87%, positive predictive value 87%, negative predictive value 80%, and odds ratio 26.7). We conclude that adult respiratory distress syndrome behaves clinically as a single disease regardless of the underlying cause; its course and outcome are dependent on the magnitude of alveolar injury. We speculate that strategies for minimizing secondary lung injury may benefit all patients with adult respiratory distress syndrome.

Correlation of plasma cytokine elevations with mortality rate in children with sepsis.

Cytokines are thought to be important endogenous mediators of the host immune response to bacterial infection. We hypothesized that plasma levels of cytokines are elevated in children with sepsis and that the magnitude of elevation of these cytokines is correlated with severity of illness and mortality rate. We determined plasma levels of tumor necrosis factor, interleukin-6, and interleukin-1 in 21 children with sepsis. Plasma samples were collected at presentation and at 12, 24, and 48 hours thereafter. Cytokine levels were elevated in pediatric patients with bacterial sepsis during the first 48 hours after presentation; levels were undetectable in study control subjects. The tumor necrosis factor and interleukin-6 levels (p less than 0.001), as well as levels of interleukin-1 (p = 0.05), were significantly higher in nonsurvivors than in survivors and were independent of severity of illness (pediatric risk of mortality (PRISM) score) at presentation. Elevations of tumor necrosis factor and interleukin-6 were sustained for longer than 24 to 48 hours in nonsurvivors: II-1 concentrations were significantly increased only at time zero. Of 11 children with an interleukin-6 value greater than 2 ng/ml during the first 48 hours, 10 died; only one of 10 not reaching that level died (p less than 0.001). Cytokines were elevated as frequently with gram-positive as with gram-negative infections. We speculate that cytokine determinations may identify children who might benefit from immunotherapeutic interventions.

Sodium restriction versus daily maintenance replacement in very low birth weight premature neonates: a randomized, blind therapeutic trial.

To test the hypothesis that restriction of sodium intake during the first 3 to 5 days of life will prevent the occurrence of hypernatremia and the need for administration of large fluid volumes, we prospectively and randomly assigned 17 babies (mean +/- SD: 850 +/- 120 gm; 27 +/- 1 weeks of gestation) to receive in blind fashion either daily maintenance sodium or salt restriction with physician-prescribed parenteral fluid intake. Maintenance-group infants received 3 to 4 mEq of sodium per kilogram per day; restricted infants received no sodium supplement other than with such treatments as transfusion. Sodium balance studies conducted for 5 days demonstrated that maintenance salt intake resulted in a daily sodium balance near zero, whereas sodium-restricted infants continued to excrete urinary sodium at a high rate, which promoted a more negative balance (average daily sodium balance -0.30 +/- 1.78 SD in maintenance group vs -3.71 +/- 1.47 mEq/kg per day in restriction group; p less than 0.001). Care givers tended to prescribe daily increases in parenteral fluids for the salt-supplemented infants, perhaps because serum sodium concentrations were elevated in these infants after the first day of the study (p less than 0.001). Hypernatremia developed in two sodium-supplemented infants (greater than 150 mEq/L), and hyponatremia developed in two sodium-restricted infants (less than 130 mEq/L); however, the restricted infants were more likely to have normal serum osmolality (p less than 0.05). Both groups of infants produced urine that was neither concentrated nor dilute, with a high fractional excretion of sodium; renal failure was not observed. The mortality rate was not affected, but the incidence of bronchopulmonary dysplasia was significantly less in the sodium-restricted babies (p less than 0.02). We conclude that in tiny premature infants, a fluid regimen that restricts sodium may simplify parenteral fluid therapy targeted to prevent hypernatremia and excessive administration of parenteral fluids.

Pulmonary mechanics in infants after cardiac surgery.

OBJECTIVE: To determine pulmonary mechanical characteristics in neonates after cardiac surgery. DESIGN: A prospective study. SETTING: A 23-bed, pediatric ICU in a 280-bed children's hospital. PATIENTS: Twenty-six infants on the first post-operative day after cardiac surgery. METHODS: Pulmonary mechanics measurements were made during spontaneous breathing, using the esophageal balloon technique and a pneumotachometer. The least mean square method of analysis was used to calculate mechanics. Infants who tolerated withdrawal of mechanical ventilation (group 1) were compared with those infants with respiratory failure (group 2). RESULTS: Spontaneous respiratory rate, tidal volume, and minute ventilation were similar in groups 1 and 2. Lung compliance was decreased, with no difference between groups. Total lung resistance (34.3 +/- 21.6 cm H2O/L.sec in group 1 vs. 136.8 +/- 105.8 cm H2O/L.sec in group 2, p = .002) and resistive work of breathing (33.4 +/- 29.9 g.cm/kg in group 1 vs. 212.9 +/- 173.8 g.cm/kg in group 2, p = .001) were significantly higher in group 2. All infants with a total lung resistance greater than 75 cm H2O/L.sec exhibited respiratory failure (resistance greater than 75 cm H2O/L.sec correlated with respiratory failure, r2 = .73, odds ratio of 70 [confidence interval, 4.4 to 3240], p less than .001). CONCLUSIONS: Increased lung resistance identifies neonates with respiratory failure after cardiac surgery. Pulmonary mechanics testing may be useful in timing withdrawal of mechanical ventilation.