Spillover of Early Extubation Practices From the Pediatric Heart Network Collaborative Learning Study

OBJECTIVES

The Pediatric Heart Network Collaborative Learning Study used collaborative learning strategies to implement a clinical practice guideline that increased rates of early extubation after infant repair of tetralogy of Fallot and coarctation of the aorta. We assessed early extubation rates for infants undergoing cardiac surgeries not targeted by the clinical practice guideline to determine whether changes in extubation practices spilled over to care of other infants.

DESIGN

Observational analyses of site's local Society of Thoracic Surgeons Congenital Heart Surgery Database and Pediatric Cardiac Critical Care Consortium Registry.

SETTING

Four Pediatric Heart Network Collaborative Learning Study active-site hospitals.

PATIENTS

Infants undergoing ventricular septal defect repair, atrioventricular septal defect repair, or superior cavopulmonary anastomosis (lower complexity), and arterial switch operation or isolated aortopulmonary shunt (higher complexity).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Aggregate outcomes were compared between the 12 month pre-clinical practice guideline and 12 months after study completion (Follow Up). In infants undergoing lower complexity surgeries, early extubation increased during Follow Up compared with Pre-Clinical Practice Guideline (30.2% vs 18.8%, p = 0.006), and hours to initial postoperative extubation decreased. We observed variation in these outcomes by surgery type, with only ventricular septal defect repair associated with a significant increase in early extubation during Follow Up compared with Pre-Clinical Practice Guideline (47% vs 26%, p = 0.006). Variation by study site was also seen, with only one hospital showing an increase in early extubation. In patients undergoing higher complexity surgeries, there was no difference in early extubation or hours to initial extubation between the study eras.

CONCLUSIONS

We observed spillover of extubation practices promoted by the Collaborative Learning Study clinical practice guideline to lower complexity operations not included in the original study that was sustainable 1 year after study completion, though this effect differed across sites and operation subtypes. No changes in postoperative extubation outcomes following higher complexity surgeries were seen. The significant variation in outcomes by site suggests that center-specific factors may have influenced spillover of clinical practice guideline practices.

Platelet Inhibition in Shunted Infants on Aspirin at Short and Midterm Follow-Up

There are few data to guide aspirin therapy to prevent shunt thrombosis in infants. We aimed to determine if aspirin administered at conventional dosing in shunted infants resulted in ≥50% arachidonic acid (AA) inhibition in short and midterm follow-up using thromboelastography with platelet mapping (TEG-PM) and to describe bleeding and thrombotic events during follow-up. We performed a prospective observational study of infants on aspirin following Norwood procedure, aortopulmonary shunt alone, or cavopulmonary shunt surgery. We obtained TEG-PM preoperatively, after the third dose of aspirin, at the first postoperative clinic visit, and 2-8 months after surgery. The primary outcome was the proportion of subjects with ≥50% AA inhibition on aspirin. All bleeding and thrombotic events were collected. Of 24 infants analyzed, 13% had ≥50% AA inhibition at all designated time points after aspirin initiation; 38% had ≥50% AA inhibition after the third aspirin dose of aspirin, 60% at the first postoperative clinic visit, and 26% 2-8 months after surgery. Bleeding events occurred in eight subjects, and two had a thrombotic event. Bleeding events were associated with greater AA inhibition just prior to starting aspirin (p = 0.02) and after the third dose of aspirin (p = 0.04), and greater ADP inhibition before surgery (p = 0.03). The majority of infants failed to consistently have ≥50% AA inhibition when checked longitudinally postoperatively. Preoperative TEG-PM may be useful in identifying infants at higher risk of bleeding events on aspirin in the early postoperative period. Further research is needed to guide antiplatelet therapy in this population.

Utilizing a Collaborative Learning Model to Promote Early Extubation Following Infant Heart Surgery

OBJECTIVE

To determine whether a collaborative learning strategy-derived clinical practice guideline can reduce the duration of endotracheal intubation following infant heart surgery.

DESIGN

Prospective and retrospective data collected from the Pediatric Heart Network in the 12 months pre- and post-clinical practice guideline implementation at the four sites participating in the collaborative (active sites) compared with data from five Pediatric Heart Network centers not participating in collaborative learning (control sites).

SETTING

Ten children's hospitals.

PATIENTS

Data were collected for infants following two-index operations: 1) repair of isolated coarctation of the aorta (birth to 365 d) and 2) repair of tetralogy of Fallot (29-365 d). There were 240 subjects eligible for the clinical practice guideline at active sites and 259 subjects at control sites.

INTERVENTIONS

Development and application of early extubation clinical practice guideline.

MEASUREMENTS AND MAIN RESULTS

After clinical practice guideline implementation, the rate of early extubation at active sites increased significantly from 11.7% to 66.9% (p < 0.001) with no increase in reintubation rate. The median duration of postoperative intubation among active sites decreased from 21.2 to 4.5 hours (p < 0.001). No statistically significant change in early extubation rates was found in the control sites 11.7% to 13.7% (p = 0.63). At active sites, clinical practice guideline implementation had no statistically significant impact on median ICU length of stay (71.9 hr pre- vs 69.2 hr postimplementation; p = 0.29) for the entire cohort. There was a trend toward shorter ICU length of stay in the tetralogy of Fallot subgroup (71.6 hr pre- vs 54.2 hr postimplementation, p = 0.068).

CONCLUSIONS

A collaborative learning strategy designed clinical practice guideline significantly increased the rate of early extubation with no change in the rate of reintubation. The early extubation clinical practice guideline did not significantly change postoperative ICU length of stay.

Transthoracic echocardiographic predictors of left atrial hypertension in patients on venoarterial extracorporeal membrane oxygenation

Decompression of the left heart in patients supported with extracorporeal membrane oxygenation (ECMO) is often warranted to protect the myocardium and facilitate recovery. We studied the ability of standard echocardiographic parameters to predict left atrial hypertension by reviewing 3 cardiac patients supported with ECMO who subsequently underwent left atrial decompression. We found that standard echocardiographic parameters poorly predict the need for left atrial decompression on ECMO. Following a more specific diagnostic algorithm to estimate left-sided filling pressure in patients with depressed ejection fraction may significantly improve the ability of echocardiography to accurately predict left atrial hypertension and the need for decompression.

Heterotaxy syndrome: impact of ventricular morphology on resource utilization

Patients with heterotaxy syndrome (HS) have significant cardiac and extracardiac anomalies that impact outcome. To improve the management of this complex patient population, we performed a comprehensive analysis of their anatomic and clinical features along with an evaluation of resource utilization data. The objectives were to describe anatomic and clinical features of patients with HS syndrome treated at a single center from 1992 to 2011 focusing on the impact of ventricular morphology (univentricular [UV] vs. biventricular [BV]) on clinical outcomes and resource utilization. Clinical and echocardiographic data from patients with HS were abstracted from medical records. Health care costs were indexed to inflation. Seventy-eight patients were identified with HS ranging in age from 1 day to 29 years old. UV morphology was present in 46 patients (59 %), most commonly with right-ventricular dominance (36 of 46). The presence of extra cardiac anomalies did not differ between the UV and BV groups (82 vs. 78 %) nor did morbidities, such as need for enteral tube feedings (47 vs. 25 %) or pacemaker placement (24 vs. 25 %). Mortality was 28 % in the entire cohort: 39 % in univentricuar patients versus 10.5 % in those with biventricular anatomy. Hospital length of stay for medical illnesses was similar in both groups, but length of stay after surgery was significantly longer in UV than BV patients. Among survivors, UV patients had greater median hospital costs (TeX 67,732, p < 0.001), but when this was adjusted for mortality and variable follow-up, there were no differences in health care costs within the first year of life. Significant health care dollars are used to manage children with HS, the majority of which involve expenses related to surgical care. Although patients with biventricular morphology have better survival, morbidity and resource utilization are similar to those for UV patients especially within the first year of life.

Simple Versus Complex Truncus Arteriosus

This study examined simple versus complex forms of truncus arteriosus (TA) results in the current era with regard to mortality, reintervention, and resource utilization. From 1999 to 2008, 42 infants underwent primary repair of TA, including 22 simple forms of TA without associated anomalies and 20 complex forms with risk factors such as interrupted aortic arch (n = 8), coarctation (n = 1), significant truncal valve regurgitation (n = 6), discontinuous pulmonary arteries (n = 3), and truncal valve stenosis (n = 2). There were 4 early deaths (4/42, 9.5%), with no difference between simple TA (2/22, 9.1%) and complex TA (2/20, 10%). Early mortality decreased to 1 patient (1/23, 4%) in the most recent era: 2003-2008. Late mortality occurred in 4 (4/38, 10.5%). Reintervention was required in 12 patients, a median of 2 years postoperatively: for conduit reasons in 8 and combined conduit and truncal valve insufficiency in 4. Actuarial survival was 82% ± 7% at 5 years and freedom from reintervention was 52% ± 17% at 5 years, which are not different between complex and simple forms. Complex TA, age, and weight were not predictors on multivariable analysis for early or late death or reintervention. Complex TA had significantly longer ( P < .05) median length of stay (17 vs 13 days) and intensive care unit intubation times (8 vs 5 days) versus simple TA. Complex TA does not have a higher operative or late mortality risk or increased risk of reintervention compared with simple TA. However, complex patients can be expected to have increased resource utilization as compared with simple forms of TA.

Management of deep wound complications with vacuum-assisted therapy after Berlin Heart EXCOR ventricular assist device placement in the pediatric population

Wound complications after ventricular assist device (VAD) placement remain a formidable challenge to surgeons. The Berlin Heart EXCOR VAD is a versatile pulsatile system that has been successful in pediatric patients of all ages and sizes. Prevention of device-related complications such as infection, particularly in pediatric patients, remains an essential issue in minimizing patient morbidity and mortality. The introduction of vacuum-assisted wound closure (VAC) therapy and its application in VAD-related wound complications provide an efficient and effective method for wound healing. We report our experience in the management of deep wound complications in two pediatric patients after placement of the Berlin Heart EXCOR VAD. The wound VAC system proved to achieve complete wound healing without any infectious complications.

Effect of red blood cell transfusion on oxygen consumption in the anemic pediatric patient

OBJECTIVE

To compare oxygen consumption (Vo(2)) measured by indirect calorimetry before and after a packed red blood cell (PRBC) transfusion in patients with isovolemic anemia.

DESIGN

Prospective, repeated-measures clinical study.

SETTING

Outpatient pediatric hematology-oncology clinic.

PATIENTS

A total of 17 pediatric hematology-oncology outpatients undergoing a PRBC transfusion for a hematocrit of <26%.

INTERVENTIONS

Vo(2) was measured by indirect calorimetry before and after a PRBC transfusion.

MEASUREMENTS AND MAIN RESULTS

Baseline hematocrit averaged 23% (15.5-25.7%), hemoglobin averaged 8.24 g/dL (5.2 g/dL-9.3 g/dL). Patients received an average of 10.3 mL/kg (2.8-17.5 mL/kg) of PRBC. After PRBC transfusion, all patients had an increase in Vo(2), with a mean increase of 35.09 mL x min(-1) x m(-2) (5-75 mL x min(-1) x m(-2)) or 19% (3.1-52%; p <.001). No significant correlation was found between the pretransfusion hematocrit or the volume of red blood cells administered and the change in Vo(2). No significant change was noted in systolic blood pressure or respiratory rate. There were 14 patients who had a decrease in heart rate after PRBC transfusion, and seven patients who demonstrated an increase in Vo(2) of <10% were compared with patients with a > or =10% change. No significant difference was found in age, height, weight, initial hematocrit, or volume of red blood cells transfused between these two groups.

CONCLUSIONS

A significant increase in Vo(2) was noted after a red blood cell transfusion in pediatric patients with isovolemic anemia. These findings suggest that Vo(2) was dependent on the supply of oxygen in this subset of pediatric patients. Responding to increased oxygen delivery by increasing Vo(2) implies that these patients were functioning in a state of relative oxygen deficit and had made physiologic adaptive changes to function in this state.

Effect of neuromuscular blockade on oxygen consumption and energy expenditure in sedated, mechanically ventilated children

OBJECTIVE

To quantify the effects of neuromuscular blockade (NMB) on energy expenditure for intubated, mechanically ventilated, critically ill children.

DESIGN

A prospective, unblinded clinical study. Each subject was studied twice, before and after establishment of NMB.

SETTING

A tertiary care pediatric intensive care unit.

PATIENTS

Critically ill children undergoing mechanical ventilation and receiving ongoing sedation were eligible, if they had a cuffed endotracheal tube and were physiologically stable.

INTERVENTIONS

A total of 20 children (age, 1 to 15 yrs) were studied in an unblinded, crossover fashion. All were mechanically ventilated via a cuffed endotracheal tube, with ventilator rate and tidal volume adequate to provide complete ventilation, and F(IO2) <0.6. Absence of gas leak around the endotracheal tube was assured, and all patients were sedated using continuous infusions of midazolam and/or fentanyl; no changes in ventilator settings, nutritional input, or inotropic drug dose were permitted during the study period. Each patient underwent indirect calorimetry immediately before establishment of NMB. NMB was then induced, and indirect calorimetry was repeated. Complete blockade was verified using a peripheral nerve stimulator. In each case, the two sets of measurements were completed within a 1-hr period.

MEASUREMENTS AND MAIN RESULTS

Data analyzed included identifying and diagnostic information, oxygen consumption, and carbon dioxide production. Energy expenditure was calculated using standard formulas. Oxygen consumption and energy expenditure values obtained before and after the establishment of NMB were compared by using paired Student's t-test. NMB reduced oxygen consumption from 6.54+/-0.49 mL/kg/min to 5.90+/-0.40 ml/kg/min, and energy expenditure was reduced from 46.5+/-3.7 kcal/kg/24 hrs to 41.0+/-2.8 kcal/kg/24 hrs (p < .001 in each case). The reduction in oxygen consumption was 8.7+/-1.7%, and that in energy expenditure 10.3+/-1.8%, of pre-NMB values, respectively.

CONCLUSION

NMB significantly reduces oxygen consumption and energy expenditure in critically ill children who are sedated and mechanically ventilated; the degree of reduction is small.

Nonradiographic assessment of enteral feeding tube position

OBJECTIVE

To determine whether a clinical, nonradiographic criterion can be used to predict when the tip of a blindly placed feeding tube is in the small intestine.

DESIGN

Prospective sample.

SETTING

Pediatric intensive care unit at a tertiary care children's hospital.

PATIENTS

Critically ill children requiring transpyloric feeding.

INTERVENTIONS

The small bowel was intubated, using a blind, bedside transpyloric feeding tube placement protocol. The feeding tube was considered to be in the small bowel when <2 mL of a 10- mL aliquot of insufflated air could be aspirated from the feeding tube. This clinical criterion was confirmed with an abdominal radiograph.

MEASUREMENTS AND MAIN RESULTS

Patient age ranged from 1 month to 19 yrs (median 6 months). Weight ranged from 2.2 to 60 kg (median 4.9). Median time to feeding tube placement was 10 mins (range 5 to 60). Eighty-nine percent of the patients were mechanically ventilated, while 28% of these patients were pharmacologically paralyzed. Seventy-five feeding tubes were inserted. There were no known complications. Ninety-nine (74/75) percent of the feeding tubes were positioned in the small bowel. The inability to aspirate insufflated air correctly predicted small bowel intubation with 99% certainty (Sequential Probability Ratio Test, p = .05 and power = .80). This test incorrectly predicted the position of only one feeding tube, the 26th, which was in the stomach. Of the 74 feeding tubes positioned in the small bowel, 13 feeding tubes were in the duodenum and 61 were in the jejunum.

CONCLUSIONS

The inability to aspirate insufflated air confirms the transpyloric position of a feeding tube. Other clinical criteria did not successfully predict small bowel intubation. Use of this single test may obviate confirmatory abdominal radiographs in carefully selected patients and may lead to more cost-effective and timely initiation of enteral feedings.

A randomized, controlled study of the 1-hour and 24-hour effects of inhaled nitric oxide therapy in children with acute hypoxemic respiratory failure

STUDY OBJECTIVE

To determine whether 24 h of inhaled nitric oxide improves oxygenation greater than conventional therapy alone in children with acute hypoxemic respiratory failure.

DESIGN

Prospective, randomized, controlled study.

SETTING

Twenty-six-bed pediatric ICU in a tertiary children's hospital.

PATIENTS

Twenty-four patients with acute bilateral lung disease requiring a positive-end expiratory pressure >6 cm H2O and a fraction of inspired oxygen >0.5 for >12 h.

INTERVENTIONS

Twelve patients were treated with 10 ppm inhaled nitric oxide from the onset of randomization and 12 control patients were initially maintained on a regimen of conventional therapy alone. After a period of 24 h, control patients were also treated with 10 ppm inhaled nitric oxide. Hemodynamic and blood gas measurements were performed at baseline, at 1 h after randomization, and at 24-h intervals for 2 days.

MEASUREMENTS AND RESULTS

Inhaled nitric oxide decreased the ratio of pulmonary to systemic vascular resistance and improved oxygenation indexes during the initial hour following randomization. However, 24 h after randomization, the oxygenation indexes of 11 surviving treated patients were not improved in comparison to baseline or the oxygenation indexes of 10 surviving control patients. Oxygenation indexes acutely improved in control patients when inhaled nitric oxide was started after 24 h of conventional therapy. Oxygenation indexes remained improved in the initial control patients after 24 h of inhaled nitric oxide.

CONCLUSIONS

Pulmonary vascular resistance and systemic oxygenation are acutely improved by 10 ppm inhaled nitric oxide in some children with severe lung disease. However, a sustained improvement in oxygenation may not occur during prolonged therapy. Thus, inhaled nitric oxide may have a limited therapeutic role in children with acute hypoxemic respiratory failure.

Comparison of simultaneously obtained arterial and capillary blood gases in pediatric intensive care unit patients

OBJECTIVE

To determine whether capillary blood gas measurements provide a clinically acceptable estimate of arterial pH, PCO2, and PO2.

DESIGN

Prospective convenience sample.

SETTING

Pediatric intensive care unit at a referral children's hospital.

PATIENTS

Fifty children > 1 month of age with indwelling arterial catheters.

INTERVENTIONS

A local anesthetic was applied to the third finger of the hand contralateral to a radial artery catheter. After 90 mins, simultaneous arterial and capillary blood gases were drawn.

MEASUREMENTS AND MAIN RESULTS

Arterial and capillary pH, PcO2, and PO2 were measured. Heart rate and Wong/Baker faces score were noted before and during capillary blood gas collection to assess discomfort associated with blood collection. There was a strong correlation between capillary and arterial pH (r2 = .903, p < .0001). The relative average bias of the capillary pH was 0.009, with capillary lower than arterial and 95% limits of agreement of +/- 0.032. In all patients, the absolute value of the difference between arterial and capillary pH was < or = 0.05. There was a strong correlation between arterial and capillary PCO2 (r2 = .955, p < .0001). The relative average bias of the capillary PCO2 was 1.6 torr (0.21 kPa), with capillary higher than arterial and 95% limits of agreement of +/- 4.5 torr (+/- 0.6 kPa). In two of 50 patients, the absolute value of the difference between arterial and capillary PCO2 was > 6.5 torr (> 0.87 kPa). Despite a statistically significant correlation between capillary and arterial PO2 (r2 = .358, p < .0001), the absolute value of the difference between arterial and capillary PO2 was > 6.5 torr (> 0.87 kPa) in 42 of 50 patients. Pain, endotracheal intubation, vasoactive drips, or pharmacologic paralysis did not affect accuracy of the capillary pH or PCO2.

CONCLUSIONS

Capillary blood gases accurately reflect arterial pH and PCO2 in most pediatric intensive care unit patients. Capillary samples did not significantly underestimate arterial hypercarbia or acidosis. This conservative reflection of metabolic status may be particularly useful in hemodynamically stable patients with mild-to-moderate lung disease.

Metabolic measurements during mechanical ventilation in the pediatric intensive care unit

The metabolism of critically ill infants and children is significantly influenced by their underlying diseases, and standard predictive equations result in inappropriate nutritional support in most of these patients. Furthermore, significant day-to-day variability in energy expenditure may be present in individual patients. Inadequate or excessive energy supply can adversely affect the clinical course of many critically ill patients. For these reasons, serial measurements of energy expenditure should be considered whenever accurate determination of energy needs is deemed necessary. With the wide availability of proprietary metabolic carts suitable for use in mechanically ventilated pediatric patients, serial metabolic measurements via indirect calorimetry are feasible in most critically ill infants and children. The use of indirect calorimetry should also be considered in this population to assess changes in oxygen consumption and the relationship of oxygen consumption to oxygen delivery in response to changes in therapy, such as manipulation of cardiac output using vasoactive medications, or during weaning of mechanical ventilation.

Dose-ranging evaluation of bumetanide pharmacodynamics in critically ill infants

OBJECTIVES

Determine the diuretic effects of single intravenous doses of bumetanide in volume-overloaded critically ill infants.

METHODS

A prospective, open-label study was carried out in 56 infants aged 0 to 6 months who required diuretic therapy. Each patient received a single intravenous dose of bumetanide. Doses selected in sequential order ranged from 0.005 to 0.10 mg/kg. Determinations of urine volume, electrolytes, creatinine levels, and osmolality were performed before (collected from -2 to -4 hours to time 0) and at 1, 2, 3, 4, 6, and 12 hours after bumetanide dosing. Serum samples collected at time 0 and at 5, 15, 30, 60, 120, 180, 240, 360, and 480 minutes and urine aliquots collected at time 0, 0 to 1, 1 to 2, 2 to 3, 3 to 4, 4 to 6, and 6 to 12 hours were analyzed for bumetanide concentration. Individual changes in urine flow rate and electrolyte excretion were plotted against corresponding bumetanide excretion rates, taken as the effective dose of the drug.

RESULTS

Peak bumetanide excretion rates increased linearly with increasing doses of drug. Time course patterns for urine flow rate and electrolyte excretion were similar for all dosage groups. Urine flow rate and electrolyte excretion increased linearly up to a bumetanide excretion rate of approximately 7 micrograms/kg/hr and either plateaued (urine flow rate) or declined at a bumetanide excretion rate of > 10 micrograms/kg/hr. Diuretic efficiency of bumetanide was maximal at doses of 0.005 to 0.010 mg/kg but decreased at higher doses.

CONCLUSIONS

Maximal diuretic responses occurred at a bumetanide excretion rate of about 7 micrograms/kg/hr, corresponding to doses of 0.035 to 0.040 mg/kg. Higher doses produced a proportionately higher bumetanide excretion rate but no increased diuretic effect. Lower doses of bumetanide had the greatest diuretic efficiency, suggesting that continuous infusion of low doses of bumetanide or intermittent low-dose boluses may produce optimal diuretic responses in critically ill infants.

Analysis of the variability in the pharmacokinetics and pharmacodynamics of bumetanide in critically ill infants

OBJECTIVES

Account for the interindividual variability in the pharmacokinetics and pharmacodynamics of bumetanide after intravenous administration of single doses to critically ill infants.

METHODS

This prospective open-label study was carried out in the pediatric intensive care unit of a university-based children's hospital. Fifty-three volume-overloaded critically ill infants (age range, 4 days to 6 months) were divided into two groups: those with heart disease (31 infants) and those with lung disease (22 infants). Each patient received a single intravenous bolus dose of bumetanide. Doses, selected in sequential order, ranged from 0.005 to 0.100 mg/kg. Age was used as a continuous variable to determine its effects on the variability in the pharmacokinetics and pharmacodynamics of bumetanide. Hierarchical multiple regression analyses were used to assess the effects of age, disease, and other drugs on the variability in the effects of bumetanide.

RESULTS

Total clearance, renal clearance, and nonrenal clearance of bumetanide all increased with age (p < 0.05), but the ratio of renal clearance to total clearance remained constant at about 0.4. Half-life and mean residence time decreased markedly in the first month of life (p < 0.05). Bumetanide excretion rate normalized for dose also increased with increasing age. Patients with lung disease exhibited a significantly greater clearance and shorter half-life (p < 0.05) than those with heart disease, whereas volume of distribution was similar in both groups. The primary determinant of bumetanide excretion rate was the administered dose (73%). Dose-response curves for urine flow rate and electrolyte excretion were similar between disease groups. The time course of the effect of bumetanide excretion rate on pharmacodynamics responses was similar between disease groups, as was the duration of the diuretic effect.

CONCLUSIONS

The pharmacokinetics of bumetanide were influenced significantly by age and disease. Differences in pharmacokinetics between patients with lung and heart disease were primarily due to differences in total clearance. The administered dose of bumetanide and age were positive determinants of bumetanide excretion rate and pharmacodynamic responses. Pharmacodynamic responses as a function of bumetanide excretion rate were not significantly different between disease groups.

Eliminating sleep-associated hypoxemia improves growth in infants with bronchopulmonary dysplasia

OBJECTIVE

Infants with bronchopulmonary dysplasia (BPD) have been previously reported to have a decrease in growth velocity after stopping supplemental oxygen (SO). SO was stopped after a short-term recording (20-30 minutes) of pulse oxygen saturation (Sao2) of 92% or greater in room air. Other studies have documented that Sao2 decreases further during feedings and sleep in infants with BPD. Two questions were asked: (1) whether short-term, awake Sao2 studies would reliably predict prolonged sleep Sao2; and (2) how Sao2 sustained at 88% to 91% vs 92% or greater in room air would impact growth velocity in infants with BPD.

METHODOLOGY

Short-term Sao2 studies were prospectively compared with prolonged sleep Sao2 (n = 63) and the growth velocity of infants who had SO discontinued after a prolonged sleep Sao2 recording of 88% to 91% (group 1; n = 14) versus 92% or greater (group 2; n = 34) in room air.

RESULTS

Failure to maintain Sao2 at predetermined levels occurred in 18 (29%) of 63 infants during their first prolonged sleep study. There was no correlation between short-term awake Sao2 and prolonged sleep Sao2 recordings (r = .02). Body weight, height, weight for height, and rate of weight gain were similar for all study infants before SO was stopped and remained constant for group 2 infants after SO was stopped. However, group 1 infants had a significant decrease in the rate of weight gain (17.3 +/- 13.1 vs 3.7 +/- 6.1 g/kg per day), and the mean z scores for weight gain and weight for height also decreased significantly for group 1 infants. Energy intake, incidence of acute infection, hematocrit values, and medication use did not differ before or after stopping SO in either group.

CONCLUSIONS

This study indicated that short-term, awake Sao2 measurements do not predict prolonged sleep Sao2, and overall, infants with BPD continued a positive growth trend when Sao2, remained greater than 92% during prolonged sleep.

Pharmacokinetics of bumetanide in critically ill infants

OBJECTIVE

Define the pharmacokinetics of bumetanide after single intravenous doses in volume-overloaded critically ill infants.

METHODS

A prospective, open-label study was carried out in a group of 58 infants aged 0 to 6 months who required diuretic therapy. Each patient received a single dose of intravenous bumetanide. Doses selected in sequential order ranged from 0.005 to 0.10 mg/kg. Hematologic and serum chemistry studies were performed before and at 6 and 24 hours after bumetanide administration. Determinations of urine volume and chemistries were performed before (collected from -2 to -4 hours to time 0) and at 1, 2, 3, 4, 6, and 12 hours after bumetanide dosing. Serum samples collected at time 0 and at 5, 15, 30, 60, 120, 180, 240, 360, and 480 minutes and urine collected at time 0 and at 0 to 1, 1 to 2, 2 to 3, 3 to 4, 4 to 6, and 6 to 12 hours were analyzed for bumetanide concentration. Data were evaluated by standard noncompartmental pharmacokinetic techniques.

RESULTS

Peak serum bumetanide concentrations occurred at 5 minutes after bumetanide administration. Area under the curve and peak serum bumetanide concentrations showed linear increases over the twentyfold dose range; whereas beta volume of distribution, volume of distribution at steady state, clearance, renal clearance, half-life, and mean residence time values were independent of dose. Peak urinary excretion rates of bumetanide increased linearly with increasing doses. The mean percent of bumetanide recovered in the urine from 0 to 12 hours was 40% +/- 15% of the administered dose.

CONCLUSIONS

Distribution and elimination kinetics of bumetanide were similar in all patients. Elimination kinetics were first order over the dose range of 0.005 to 0.10 mg/kg. Pharmacokinetic parameter estimates (beta volume of distribution, volume of distribution at steady state, clearance, renal clearance, half-life, and mean residence time) were independent of the dose of bumetanide administered. Single doses of bumetanide up to 0.10 mg/kg appear to be well tolerated in acutely ill volume-overloaded infants aged 0 to 6 months.

Racemic versus l-epinephrine aerosol in the treatment of postextubation laryngeal edema: results from a prospective, randomized, double-blind study

OBJECTIVE

To determine whether any advantage exists using racemic epinephrine instead of the more potent and less expensive levo(1)-epinephrine in the treatment of postextubation laryngeal edema.

DESIGN

Prospective, double-blind, randomized study.

SETTING

Pediatric intensive care unit in a university teaching hospital.

PATIENTS

Twenty-eight patients with stridor during the immediate postextubation period.

INTERVENTIONS

After extubation, patients demonstrating clinically important stridor were randomized in a double-blind fashion to receive an aerosol containing either 2.25% racemic or 1% l-epinephrine.

MEASUREMENTS AND MAIN RESULTS

Heart rate, respiratory rate, blood pressure, and stridor score were determined at 20, 40, and 60 mins and 4 and 8 hrs after the initial aerosol administration. Patients in both groups demonstrated significant (p < .01) reductions in stridor score after aerosol administration. No significant differences were observed between treatment groups in improvement in stridor score or the number of subsequent aerosols required. Respiratory rate decreased significantly 40 and 60 mins after l-epinephrine but not after racemic epinephrine. No significant change in heart rate or blood pressure occurred after aerosol administration in either group.

CONCLUSIONS

These data suggest that aerosolized l-epinephrine is as effective as aerosolized racemic epinephrine in the treatment of postextubation laryngeal edema without additional adverse side effects. When dosed appropriately, l-epinephrine is a less expensive and more widely available alternative to racemic epinephrine for the treatment of postextubation laryngeal edema.

Prolongation of inspiration during lower airway occlusion in children

Inspiration is strongly inhibited by volume-related vagal afferents in human neonates and animals, but this reflex is not as active in human adults during normal breathing. To determine whether volume-related inspiratory inhibition occurs beyond the neonatal period, we performed 10 +/- 1 end-expiratory occlusions in nine asleep children, ages 2-29 mo, with cuffed tracheostomy or endotracheal tubes in place. Airflow, tidal volume, occlusion pressure, and surface diaphragm electromyogram (DIA EMG) were simultaneously recorded. Occlusion consistently increased mechanical (P less than 0.002) and neural inspiratory times (P less than 0.001). During occluded respiratory efforts, peak amplitude of DIA EMG increased by 22 +/- 10% (P less than 0.002). In contrast, initial rate of rise of DIA EMG did not change. We conclude that in children with isolated lower airways, end-expiratory occlusions prolonged inspiratory duration as measured by both mechanical and neural parameters. The lack of an associated increase in rate of rise of DIA EMG strongly suggests that inspiration is prolonged by release of volume-related inhibition of inspiration rather than by facilitation. These data provide evidence for the presence of the Hering-Breuer reflex beyond the neonatal period.

Diuretic therapeutics in the pediatric patient

Careful management of fluid and electrolytes has long been an intrinsic part of pediatric practice. However, the augmentation of these manipulations through the rational use of diuretic agents requires considerable skill. In pediatric medicine, the regulation of pharmacokinetic processes and their interface with pharmacodynamic processes show dramatic age-related changes. These ontogenetic processes and their modification by various disease states must be considered carefully before selection and application of diuretic agents. The available data concerning the ontogeny of renal function and the attempts to apply diuretic therapy to pediatric disease are reviewed. It is concluded that results obtained to date suffer from the absence of a rigorous attempt to answer the fundamental therapeutic questions: What drug? What dose? What duration of therapy? A rational "target-effect" strategy is proposed for the application of diuretic agents to pediatric medicine.

Outcome of pediatric resuscitation

A one-year prospective study of 105 resuscitations in 74 children was done at Milwaukee Children's Hospital. Resuscitation outcome was correlated to location of arrest, level of monitoring at time of arrest, and type of arrest. Type of arrest was the only analyzed variable that influenced outcome. This study indicates that outcome for children requiring resuscitation for respiratory arrest without cardiac arrest is reasonably good (25% mortality). However, the outcome for children requiring resuscitation for cardiac or cardiorespiratory arrest is poor (87% to 89% mortality or severe morbidity). Children who suffered a respiratory arrest without cardiac arrest had a better outcome than did adults. However, children who had a cardiac or cardiopulmonary arrest had the same poor outcome as did adults.