Ann E. Thompson

The impact of extracorporeal membrane oxygenation on survival in pediatric patients with acute respiratory failure

OBJECTIVE Extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency in the treatment of acute respiratory failure in pediatric patients. Our objective in this study was to test the hypothesis that ECMO improves outcome in pediatric patients with acute respiratory failure. DESIGN Multicenter, retrospective cohort analysis. SETTING Forty one pediatric intensive care units participated in the study under the auspices of the Pediatric Critical Care Study Group. PATIENTS All pediatric patients admitted to the participating institutions with acute respiratory failure during 1991 were included. Patients with congenital heart disease, contraindications to ECMO, or incomplete data were excluded, yielding a data set of 331 patients from 32 hospitals. INTERVENTIONS Conventional mechanical ventilation, high-frequency ventilation, and extracorporeal membrane oxygenation. MEASUREMENTS AND MAIN RESULTS Multivariate logistic regression analysis was used to identify factors associated with survival. In a second analysis, pairs of ECMO and non-ECMO patients, matched by severity of disease and respiratory diagnosis, were compared. The use of ECMO (p = .0082), but not the use of high-frequency ventilation, was associated with a reduction in mortality. Other factors independently associated with mortality included oxygenation index (p < .0001), Pediatric Risk of Mortality score (PRISM) (p < .0001) and the Paco2 (p = .045). In 53 diagnosis- and risk-matched pairs, there was a significantly lower mortality rate (26.4% vs. 47.2%; p < .01) in the ECMO-treated patients. When all patients were stratified into mortality risk quartiles on the basis of oxygenation index and PRISM score, the proportion of deaths among ECMO-treated patients in the 50% to 75% mortality risk quartile was less than half the proportion in the non-ECMO treated patients (28.6% vs. 71.4% p < .05)> No effect was seen in the other quartiles. CONCLUSIONS The use of ECMO was associated with an improved survival in pediatric patients with respiratory failure. The lack of association of outcome with treatment in the ECMO-capable hospital or with another tertiary technology (i.e. high-frequency ventilation) suggests that ECMO itself was responsible for the improved outcome. Further studies of this procedure are warranted but require broad-based multi-institutional participation to provide sufficient statistical power and sensitivity to demonstrate efficacy.

A prospective, randomized study of continuous versus intermittent nebulized albuterol for severe status asthmaticus in children

to determine if continuous nebulization of albuterol is more effective than intermittent nebulization in the treatment of children with status asthmaticus and impending respiratory failure; b) to determine the effect of continuous nebulization and intermittent nebulization on duration of hospital stay and bedside respiratory therapy care. Design:Prospective, randomized study. Setting:A pediatric intensive care unit (ICU) in a university childrens hospital. Patients:Seventeen pediatric asthmatic patients with severe status asthmaticus, with impending respiratory failure (Woods asthma score >5), and without evidence of cardiac or other preexisting lung disease were admitted to the pediatric ICU. The patients were randomized to receive continuous nebulization (n = 9) or intermittent nebulization (n = 8) of albuterol. Interventions:The asthmatic patients were randomized into two groups. The continuous group received 0.3 mg/kg/hr of albuterol by continuous nebulization; the intermittent group received 0.3 mg/kg of albuterol over 20 mins every hour. All patients received aerosol therapy through the same delivery system. Measurements:Responses to therapy were evaluated by following asthma score, arterial blood gas values, hemodynamics, FIO2, and arterial oxygen saturation initially and at 30 mins, 1 hr, 2 hrs, 4 hrs, then every 4 hrs for a 24-hr time period. Patients were determined to no longer be in impending respiratory failure when their asthma score was <5 for four consecutive hours. Electrocardiograms, serum electrolyte values, and creatine phosphokinase total and MB fraction values were obtained before and after treatment. Hospital stay and respiratory therapy time, in relative value units (one relative value unit = 10 mins) were analyzed from data collected from therapist bedside flow sheets. Results:The patient characteristics (demographics, hemodynamics, arterial blood gas values, asthma severity, corticosteroid use, theo-phylline, and β2-adrenergic receptor agonist administration) before entry into the study did not differ between groups. Patients in the continuous group improved more rapidly and were out of impending respiratory failure sooner than patients in the intermittent group (continuous group = 12 (median) hrs (range 4 to 24) vs. intermittent group = 18 (median) hrs (range 12 to 24; p = .03). Bedside respiratory therapy time evaluated by relative value units was less for patients who received continuous nebulization of albuterol (continuous group = 14 (median) relative value units (range 6 to 26) vs. intermittent group = 33 (median) relative value units (range 25 to 49; p = .001). Hospital stay was shorter for patients who received continuous nebulization of albuterol (continuous group = 80 [median] hrs [range 51 to 173] vs. intermittent group = 147 [median] hrs [range 95 to 256]; p = .043). Hemodynamics, serum potassium, and creatine phosphokinase concentrations did not differ before and after the study in either group. Conclusions:In children with impending respiratory failure due to status asthmaticus, continuous nebulization of albuterol is safe and results in more rapid clinical improvement than intermittent nebulization. Respiratory therapy required at the bedside and duration of hospital stay were substantially less for patients receiving continuous nebulization of albuterol, which suggests that continuous nebulization of albuterol is more cost effective than intermittent nebulization. (Crit Care Med 1993; 21:1479–1486)

Energy expenditure in critically ill children

Objectives: To measure energy expenditure in critically ill children and compare it with the energy expenditure predicted by recommended formulas, and relate the measured energy expenditure to nutritional and clinical indices. Design: A prospective, clinical study. Setting: Tertiary care pediatric intensive care unit in a university childrens hospital. Patients: A total of 37 patients with critical illness who were mechanically ventilated for ≥24 hrs were studied. Interventions: None. Measurements and Main Results: Chronic protein‐energy malnutrition (CPEM) and acute protein‐energy malnutrition were defined by the Waterlows stages and fat and protein stores were classified as defined by Frisancho, Ryan, and Martinez. Severity of illness was assessed by the Pediatric Risk of Mortality Score, the Therapeutic Intervention Scoring System, and indices of organ failure. Oxygen consumption, carbon dioxide production, and the respiratory quotient were measured by indirect calorimetry, and energy expenditure (MEE) was calculated using the modified Weir formula. Resting energy expenditure (PBMR), predicted energy expenditure, and caloric intake were calculated using recommended formulas. A total of 77 measurements were made in 37 children. MEE was significantly lower than PBMR as estimated by all equations except the Talbot equations. MEE was significantly lower than predicted energy expenditure and the recommended daily allowances. On the first day, the MEE/PBMR ratio was <0.9 in 56.8%, 0.9‐1.1 in 21.6%, and >1.1 in 21.6% of patients. MEE did not differ significantly among disease groups or between medical and surgical patients. There was no difference in MEE with or without neuromuscular blockade. MEE was lower in the presence of multiple organ system failure (MOSF) (1019 + 166 kcal/m2 without MOSF vs. 862 + 241 with MOSF; p = .025). A total of 21% had CPEM and 8.1% had acute protein‐energy malnutrition. Multivariate stepwise regression analysis showed that the protein intake, midarm muscle area, midarm fat area, the use of vasoactive agents, and sedation correlated with MEE (p < .05). With CPEM, MEE was correlated to the severity of illness (p < .05). Patients at risk for protein stores depletion (midarm muscle areas 1 and 2) had a higher incidence of MOSF compared with nutritionally normal children (p < .05), whereas patients with fat stores depletion (midarm fat area 2) had a higher probability of death (50% vs. 6%, respectively). Conclusions: Recommended daily allowances and energy expenditure predicted by using a stress‐related correction to the resting energy expenditure grossly overestimate MEE. MEE is close to PBMR and in many patients, it is lower than PBMR. MEE that is lower than PBMR is associated with a higher morbidity. Nutritional repletion should thus be based on MEE to avoid the problems of over‐ or underfeeding.

Validity of a disposable end-tidal CO2 detector in verifying endotracheal tube placement in infants and children

STUDY OBJECTIVE To examine the validity of a disposable, colorimetric end-tidal CO2 detector in verifying endotracheal tube (ETT) placement in infants and children. DESIGN The detector was studied prospectively in 151 intubations. SETTING Operating room, ICU, and emergency department of a childrens hospital. PARTICIPANTS One hundred thirty-seven children undergoing endotracheal intubation for anesthesia (52), respiratory support (76), or CPR (23). INTERVENTIONS After endotracheal intubation, tube position was verified, the detector was attached, and readings were obtained. MEASUREMENTS AND RESULTS The detector correctly identified tube position (trachea, 124; esophagus, four) in all 120 patients who were not in cardiac arrest (P less than .01). In the cardiac arrest setting, all six esophageal intubations were correctly identified, but two of the 17 tracheal intubations were incorrectly interpreted as esophageal intubations (P less than .01). CONCLUSION The detector accurately identifies ETT position in children with spontaneous circulation who weigh more than 2 kg. During CPR, a positive test correctly indicates that the ETT is in the airway, but a negative result (suggesting esophageal placement) requires an alternate means of confirming ETT position.

Femoral Vascular Catheterization in Critically Ill Infants and Children

The success rate and complications from femoral arterial and venous catheterization in infants and children in a university affiliate pediatric intensive care unit were determined prospectively over a 2-year period. We also performed a meta-analysis from published literature to determine the combined estimates of noninfectious and infectious complications (with 95% con fidence limits) using the inverse variance-weighted method. Success rates were 94.5% and 94.4% for femoral arterial (n=110) and venous (n=89) catheterizations, respectively, and were related to operator expertise, age, and hemodynamic status. Median age was 2.4 years and 1.1 year for arterial and venous catheterizations, respectively. Immediate complications were hematoma (10.9% arterial, 16.8% venous) and minor bleeding (13.6% arterial, 13.5% venous). Decreased pulses occurred with 7.7% of arterial catheterizations, and lower limb swelling occurred in 9.5% of venous catheteriza tions. Vascular complications occurred only in infants and resolved within 7-14 days. Catheter- related infections occurred in 1.9% of arterial and 3.6% of venous catheterizations. The mean dura tion of catheterization was 5.3 days and 6.3 days with femoral arterial and venous catheterizations, respectively. Meta-analysis of published studies shows that the estimates for noninfectious compli cations were 5.0%, 10.1 %, 1.1%, and 1.8% for femoral arterial, femoral venous, axillary arterial, and nonfemoral venous catheters, respectively. The estimates for catheter-related infection were 2.5%, 3.7%, and 3.0% for femoral arterial, femoral venous, and nonfemoral venous catheters, respectively. The meta-analytic estimates for complication rates from published literature are not significantly different from the rates observed in our study. Femoral arterial and venous cathe terization in infants and children are safe with an expected high success rate and acceptably low complication rates.

Portal Hypertension in Children: Expert Pediatric Opinion on the Report of the Baveno V Consensus Workshop on Methodology of Diagnosis and Therapy in Portal Hypertension

Shneider BL, Bosch J, de Franchis R, Emre SH, Groszmann RJ, Ling SC, Lorenz JM, Squires RH, Superina RA, Thompson AE, Mazariegos GV. Portal Hypertension in Children: Expert Pediatric Opinion on the Report of the Baveno V Consensus Workshop on Methodology of Diagnosis and Therapy in Portal Hypertension.

Percutaneous infraclavicular subclavian vein catheterization in critically ill infants and children

The safety and risks of percutaneous infraclavicular subclavian vein catheterization, when performed by nonsurgical staff, were studied prospectively in 100 consecutive patients. The overall success rate was 92% (with one attempt, 45%; with two attempts, 85%). The procedure was performed under emergency conditions in 35% of the patients, with a success rate of 88.6%. The success rate was significantly lower in younger patients. Hemodynamic status, respiratory status, and level of expertise of the individual performing catheterization did not affect success rate. Most of the failures (six of eight) were related to presumed thrombosis from prior cannulation of the superior vena cava. Mean duration of catheterization was 7.5 +/- 5.8 days (+/- SD). Minor complications (n = 24) included hematomas, minor bleeding from subclavian artery puncture, and transient premature ventricular ectopic beats. Major complications (n = 6) were pneumothoraces (n = 4) and catheter-related infection (n = 2). The number of attempts made to catheterize the vessel and the level of expertise of the operator had the greatest effect on complication rates. No mortality was associated with this procedure. We have found percutaneous infraclavicular subclavian vein catheterization to be a rapid alternative to surgical cutdown for venous access during cardiopulmonary resuscitation. Pediatric residents can be trained, under direct supervision, to perform this procedure with a high success rate and a low complication rate.

Chronic Middle Ear Disease and Auditory Perceptual Deficits Is There a Link

Data are presented indicating a correlation between chronic recurrent otitis media of early childhood and an increased likelihood of subsequent auditory processing deficits in a group of children referred for evaluation of impaired learning. Helpful appendices are added for a better understanding of central auditory processing skills.

Otitis media in the pediatric intensive care unit: a prospective study.

Otitis media has been previously shown to be a source of sepsis in the pediatric intensive care unit; however, pneumatic otoscopy and other otologic instruments are not commonly used in the pediatric intensive care unit. We undertook a prospective study to determine the prevalence of otitis media, to assess the risk factors involved with the development of these nosocomial infections, and to identify the causative organisms. We conclude that otitis media is a common entity in the pediatric intensive care unit, that it is probably caused by prolonged dysfunction of the eustachian tube associated with oral and nasally-placed tubes and that the bacteriology reflects that of the hospital environment and not that of the community.

Lung mechanics during and after extracorporeal membrane oxygenation for meconium aspiration syndrome

Objective:To determine whether abnormalities in lung mechanics detected in infants during the acute phase of meconium aspiration syndrome persist after treatment with extracorporeal membrane oxygenation (ECMO). Design:Prospective, descriptive study. Prospective evaluation of airway function and lung mechanics during and after ECMO by pulmonary function testing at 1.8 ± 0.5 days of EMCO (period 1), follow-up at 1.4 ± 0.2 days (period 2), and 7.0 ± 0.9 days (period 3) after decannulation from ECMO. Setting:Tertiary care neonatal/pediatric ICU. Patients:Twelve neonates undergoing ECMO treatment for severe meconium aspiration syndrome that was refractory to conventional mechanical ventilation. Interventions:Maximum expiratory flow-volume curves were studied with the deflation flow-volume curve technique, and compliance and resistance of the respiratory system were studied with partial passive flow-volume curves. Measurements and Main Results:Respiratory system compliance was the only index of respiratory mechanics that was significantly (p < .05) improved (0.96 ± 0.1 vs. 0.61 ± 0.1 mL/cm H2O/kg) immediately after decannulation from ECMO compared with period 1. Clinically important (p < .05) improvement in forced vital capacity (28.0 ± 5.5 vs. 16.1 ± 1.9 mL/kg), respiratory system compliance (1.01 ± 0.2 vs. 0.61 ± 0.1 mL/cm H2O/ kg), and maximum expiratory flow at 25%/forced vital capacity (1.0 ± 0.3 vs. 2.2 ± 0.3) was evident only during period 3 compared with period 1. Conclusions:We conclude that improvements in the clinical condition and oxygenation, permitting successful decannulation from ECMO, are achieved before clinically important improvements in lung mechanics.