Outcome-associated factors in pediatric patients treated with extracorporeal membrane oxygenator after cardiac surgery.

BACKGROUND: The use of the extracorporeal membrane oxygenator (ECMO) for postoperative cardiac patients has not resulted in the same high success rate as when ECMO is used for neonates with pulmonary hypertension or pulmonary failure. The reason for this is poorly understood. METHODS AND RESULTS: We analyzed retrospectively all pediatric patients placed on ECMO after surgery for a congenital heart lesion between 1981 and 1995 (n = 64). Patients had a two-ventricular repair (A) or pulmonary blood flow supplied by an aortopulmonary shunt (B) or by a cavopulmonary connection (C). Indication for ECMO was unsatisfactory hemodynamics due to (1) ventricular dysfunction, (2) pulmonary failure, (3) pulmonary hypertension, or (4) a combination or (5) for unclear reasons. Hospital survival was related to these and other factors. Overall hospital survival was 33%; 42% of group A patients survived to discharge, whereas only 25% and 17% survived in groups B and C, respectively. Survival was unrelated to the indication for ECMO but appeared to be lower when ECMO was initiated in the operating room or > 50 hours after surgery. Except for one patient with pneumonia, no patient survived who was on ECMO for > 208 hours. ECMO discontinuation in nonsurvivors was due to neurological (30%) or multiple complications (39%), the lack of return of cardiac function (12%), or other reasons (15%). CONCLUSIONS: This review suggests that the diagnosis of single ventricle, initiation of ECMO in the operating room or > 50 hours after surgery, and ECMO for > 208 hours are associated with patient nonsurvival. Noncardiac complications more frequently led to discontinuation of ECMO than did failure of the return of cardiac function.

Mechanical ventilation and arterial blood gas measurements 24 hours postextracorporeal life support for survivors of pediatric respiratory failure.

OBJECTIVE: To summarize our institutional experience concerning mechanical ventilation support and blood gas measurements in the 24-hr period following extracorporeal life support (ECLS) for pediatric acute respiratory failure. DESIGN: Descriptive study. SETTING: A tertiary pediatric referral center. PATIENTS: Children aged 1 month to 18 yrs treated with ECLS for acute respiratory failure at University of Michigan Hospitals from November 1982 to June 1993. All patients aged 1 month to 18 yrs who received ECLS for acute respiratory failure were included. Patients who received ECLS primarily for cardiac support or who had a diagnosis of congenital gastrointestinal malformation (i.e. congenital diaphragmatic hernia) were excluded. INTERVENTIONS: ECLS for severe pediatric respiratory failure. MEASUREMENTS AND MAIN RESULTS: Forty-nine children were treated at our center with ECLS for acute respiratory failure 36 (73%) survived. Ventilator settings immediately after decannulation from ECLS for survivors were as follows: FIO2 0.53 +/- 0.18 (SD); intermittent mandatory ventilation (IMV) 29.6 +/- 1.18 breaths/min, positive end-expiratory pressure 5.3 +/- 1.6 cm H2O, mean airway pressure 12.6 +/- 2.9 cm H2O, and peak inspiratory pressure 31.7 +/- 5.5 cm H2O. Arterial blood gas measurements at decannulation were PaO2 89.4 +/- 30.9 torr (11.9 +/- 4.1 kPa), PaCO2 43.7 +/- 9.7 torr (5.8 +/- 1.3 kPa), and pH 7.39 +/- 0.07. Twenty-four hours after decannulation, ventilator settings and arterial blood gas measurements were as follows: FIO2 0.42 +/- 0.14, IMV 27.4 +/- 13.5 breaths/min, positive end-expiratory pressure 5.2 +/- 1.6 cm H2O, mean airway pressure 12.0 +/- 3.4 cm H2O, peak inspiratory pressure 31.1 +/- 6.5 cm H2O, PaO2 77.0 +/- 16.9 torr (10.3 +/- 2.3 kPa), PaCO2 44.9 +/- 8.4 torr (6.0 +/- 1.1 kPa), and pH 7.40 +/- 0.07. Variables associated with oxygenation status (P[A-a]O2) and mean airway pressure (oxygenation index) improved during the immediate 24-hr period postbypass (p < .05). CONCLUSIONS: Successful decannulation from ECLS for > 24 hrs resulted in long-term survival in 97% (36/37) of children. Ventilator parameters and arterial blood gas measurements during the 24-hr period following bypass have been described for this population. Such conventional support may indicate safe levels of oxygen and mechanical ventilation pressures for the postbypass recovering lung.

Continuous versus intermittent nebulized terbutaline: plasma levels and effects.

The purpose of this investigation was to compare continuous versus intermittent nebulization of a beta 2-agonist, terbutaline, to determine whether differences exist in plasma concentrations or adverse cardiovascular effects of the drug with these two techniques for its administration. Sixteen children 6 to 16 yr of age, admitted for acute asthma, were enrolled in this randomized double-blind clinical trial. Nebulization of 16 mg of terbutaline over an 8-h period was performed either continuously or intermittently, with a dose of 4 mg given over 20 min every 2 h. The peak plasma terbutaline concentration for the intermittent nebulization treatment (INT) group (5.1 +/- 2.1 ng/ml) occurred 1 h after the fourth inhalation treatment and was similar to the peak concentration for the continuous nebulization treatment (CNT) group, which was reached at the end of the 8 h period (4.7 +/- 2.3 ng/ml). The maximum heart rate increase for the INT group (19.6 +/- 18.3 bpm) occurred 1 h after the fourth dose and was similar to the peak observed in the CNT group (19.6 +/- 19.2 bpm), which occurred after 3 h. Similar increases in systolic and decreases in diastolic pressures were observed for the INT and CNT groups. No evidence of serious adverse myocardial complications was seen in either group, as evidenced by measurements of the MB fraction of creatine phosphokinase (CPK-MB) and Holter-monitor recordings. Continuous nebulization of the terbutaline produces similar plasma concentrations and cardiovascular physiologic responses as intermittent nebulization.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic otitis media requiring ventilation tubes in tracheotomized ventilator dependent children.

The occurrence of sinusitis and middle ear effusions has frequently been attributed to the obstruction of the sinus ostia and/or eustachian tube. In the intensive care unit setting, edema caused by the irritation from nasogastric, nasotracheal and orotracheal tubes has been associated with this pathology and has been responsible for occult sepsis in this population. Our investigation was performed to determine the risk of chronic otitis media with effusion necessitating myringotomy with tympanostomy tubes among tracheotomized, ventilator dependent children in a consecutive series of children admitted to our recently created stable ventilator unit. We retrospectively reviewed the medical records of all tracheotomized, chronically ventilator dependent children < 48 months of age who had been hospitalized in this unit from the initial opening in September 1990 to January 1993. Data collected consisted of patient demographics, gestational age, cognitive abilities, age at onset of mechanical ventilation, age at tracheostomy, age at myringotomy, presence of nasogastric and gastroenterostomy tubes and evidence of gastric-esophageal reflux. All children underwent a tracheostomy procedure subsequent to the onset of mechanical ventilation. Of these patients, 9/12 (75%) later required myringotomy with tympanostomy tube placement following the occurrence of chronic otitis media with effusion. Ventilation tubes for chronic otitis media with effusion were not required in 3 patients. Using a case control study design, we examined the need of myringotomy tubes for children requiring continuous mechanical ventilation versus those requiring night-time only ventilation. The risk of myringotomy tubes in the continuously ventilated group (9/9) was significantly greater than the risk in the intermittently ventilated group (0/3) P < 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)

Simulated pediatric cardiopulmonary resuscitation: initial events and response times of a hospital arrest team.

BACKGROUND: Cardiopulmonary resuscitation (CPR) training programs exist to enhance knowledge and skills retention. However, they do not ensure that effective CPR will be performed by trainees or resuscitation teams. One aspect of CPR effectiveness is the ability of the team to respond to an emergency call in a timely manner. METHODS: We prospectively evaluated the time required for team members to respond to an emergency call and to initiate definitive treatment in our pediatric facility. The medical staff who responded had no prior knowledge of the simulated cardiac arrest (SCA) events. All events were recorded on audio-cassette tape to determine the sequence of events and response time of arrest team members. SCA scenarios represented examples of cardiac, hematologic, renal, respiratory, and pharmacologic pathophysiology. All participants were instructed to respond as though the SCA were an actual emergency. RESULTS: From December 1991 to January 1993, 37 SCAs were evaluated. Documentation began after a concise arrest scenario had been presented to a designated nursing representative who was to be the first rescuer on the scene. The rescuer first assessed the patient's condition, activated the cardiac arrest system (median elapsed time, MET, 0.50 minutes), and then initiated single-person CPR (MET 0.58 minutes). Administration of oxygen occurred at an MET of 2.25 minutes. The first member of the arrest team to respond was the pediatric resident (MET 3.17 minutes) followed by the respiratory therapist (MET 3.20 minutes), an ICU nurse (MET 3.58 minutes), a pharmacist (MET 3.42 minutes), and anesthesiology personnel (MET 4.70 minutes). DISCUSSION: The use of SCAs (termed "Mega Code") serves as an extension of Basic Life Support and Advanced Cardiac Life Support education and provides a valuable learning experience and quality assurance tool. Limitations that might influence patient outcome during an actual in-hospital arrest have led to refinements in our cardiac arrest procedures. Of particular note was the delay in oxygen administration, which may be linked to its omission from the 1986 and 1992 American Heart Association Basic Life Support Guidelines. CONCLUSION: We believe that BLS education for hospital employees should include and emphasize oxygen delivery for resuscitation.

Extracorporeal life support for severe pediatric respiratory failure: an updated experience 1991-1993.

OBJECTIVE: The purpose of this study was to examine our recent experience with children who had acute respiratory failure managed with extracorporeal life support (ECLS) from 1991 to 1993, to determine whether a change in survival rate had occurred in comparison with our previous experience. DESIGN: Historic and prospective cohort study. SETTING: A tertiary pediatric referral center. PATIENTS: All non-neonatal pediatric patients treated with ECLS for severe, life-threatening respiratory failure were examined. Overall, 25 patients have been managed with this life-support technique in the past 28 months. Eighty-four percent (21/25) were transferred to our medical center because of failure of conventional mechanical ventilation therapy. Descriptive data of the recent cohort were as follows (mean +/- SD): age 60 +/- 75 months, weight 23.6 +/- 24.8 kg, and male gender 44%. Duration of intubation before ECLS was 5.8 +/- 2.7 days. Arterial blood gas values and ventilator settings immediately before ECLS were as follows: fraction of inspired oxygen, 0.98 +/- 0.08; mean airway pressure, 21.6 +/- 6.2 cm H2O; peak inspiratory pressure, 45.5 +/- 9.6 cm H2O; positive end-expiratory pressure, 11.0 +/- 4.3 cm H2O; partial pressure of oxygen (arterial), 56 +/- 20 mm Hg (7.4 +/- 2.7 kilopascals); partial pressure of carbon dioxide (arterial), 46 +/- 17 mm Hg (6.1 +/- 2.3 kPa); and estimated alveolar-arterial oxygen tension difference, 572 +/- 81 mm Hg (76.3 +/- 10.8 kPa). Mean duration of ECLS was 373 +/- 259 hours. Of 25 recently treated patients, 22 (88%) survived their life-threatening respiratory illness to be discharged home; this represented a statistically improved survival rate in comparison with the 58% survival rate previously reported by us for similar patients (p < 0.05). Comparisons of arterial blood gas and mechanical ventilation-related variables measured 24 hours before and again immediately before bypass were similar in the two cohorts with the exception of higher mean partial pressure of carbon dioxide (arterial) 24 hours before bypass in the recent treatment group. For our entire experience, younger age groups had greater survival rates; 100% of infants less than 1 year of age survived. CONCLUSIONS: Treatment with ECLS is an evolving pulmonary rescue therapy with an 88% survival rate in our recent experience. The survival rate has improved to levels that may not greatly improve in the near future, especially for patients less than 1 year of age. Better patient selection or improved management strategies or both may be responsible for the improved patient outcome.

Alveolar-arterial oxygen gradients before extracorporeal life support for severe pediatric respiratory failure: improved outcome for extracorporeal life support-managed patients?

OBJECTIVE: Recent reports have described the usefulness of the alveolar-arterial oxygen tension difference (P[A-a]O2) in predicting mortality in children with acute respiratory failure managed with mechanical ventilation. We reviewed our experience with extracorporeal life support for acute pediatric respiratory failure and specifically examined P(A-a)O2 measurements during the 24 hrs before extracorporeal life support to determine if defined cutoffs established with conventional mechanical ventilation were applicable to extracorporeal life-support survival. DESIGN: Retrospective, case-series chart review. SETTING: A university tertiary medical center. PATIENTS: Infants and children (n = 36), one month to 18 yrs of age, with severe life-threatening respiratory failure who were believed to have failed conventional mechanical ventilatory support. INTERVENTIONS: Veno-venous or veno-arterial extracorporeal life support. MEASUREMENTS AND MAIN RESULTS: From 1982 to 1992, we managed 36 pediatric patients with severe respiratory failure using extracorporeal life support. We identified 28 patients who had P(A-a)O2 values of > 400 torr (> 53.3 kPa) for the 24-hr time period before placement on bypass. At the time of bypass initiation, all blood gas and mechanical ventilator parameters except PaCO2 showed trends of worsening pulmonary function, compared with measurements done 24 hrs before bypass initiation. Oxygenation-related variables showed statistically significant worsening trends when measured 24 hrs before bypass, compared with the time of bypass: P(A-a)O2 539 vs. 582 torr (71.9 vs. 77.6 kPa), p < .01; PaO2/FIO2 ratio 70 vs. 57 torr (9.3 vs. 7.6 kPa), p < .05; oxygenation index 32 vs. 47 cm H2O/torr, p < .01; and FIO2 0.94 vs. 0.98, p < .05. Sixty-one percent of extracorporeal life support-managed patients (17 of 28) survived their life-threatening respiratory illness to be discharged home. CONCLUSIONS: Based on previous reports of the utility of P(A-a)O2 measurements to predict mortality, our preliminary evidence suggests that extracorporeal life support results in 62% survival for pediatric respiratory failure patients predicted to have no chance of survival using conventional mechanical ventilation. Prospective, randomized trials of children with severe acute respiratory failure managed with mechanical ventilation vs. extracorporeal life support may be indicated.

Influence of tidal volume, respiratory rate, and supplemental oxygen flow on delivered oxygen fraction using a mouth to mask ventilation device.

We examined the influence of the following parameters in determining the FiO2 delivered to a pediatric lung model using the mouth-to-mask method of resuscitation: rate of ventilation, inspiratory tidal volumes, and supplemental oxygen flow. With a ventilator rate of 20/min and tidal volumes (Vt) < or = 100 mL, an FiO2 of approximately .50 was observed with a supplemental oxygen flow of 5 L/min. Increasing the supplemental oxygen flow to 15 L/m did not appreciably increase the FiO2 (FiO2 = .53 versus FiO2 = .60, respectively), but did cause a significant and unintended increase in Vt. Similar results were noted with a ventilator rate of 12/min and Vt < or = 100 mL (FiO2 = .68 versus FiO2 = .73, respectively). We also observed a potentially hazardous situation involving the positioning of the supplemental oxygen port that might result in high inspiratory pressures (stacking of breaths) to the pediatric patient. We believe additional testing is warranted prior to widespread use of this device in children.

Predictors of outcome of severe respiratory syncytial virus-associated respiratory failure treated with extracorporeal membrane oxygenation.

OBJECTIVE: To examine the Extracorporeal Life Support Organization registry data base for all infants and children with respiratory syncytial virus-associated respiratory failure managed with extracorporeal life support, to delineate predictors of outcome. DESIGN: Retrospective cohort study. SETTING: Extracorporeal Life Support Organization data registry. PATIENTS: All pediatric patients treated in the United States with extracorporeal life support for severe pediatric respiratory syncytial virus-associated respiratory failure reported to the registry, from 1982 through June 1992. INTERVENTIONS: Venoarterial or venovenous extracorporeal life support. MEASUREMENTS AND MAIN RESULTS: As of June 1992, fifty-three pediatric patients meeting study entry criteria were reported to the Pediatric Respiratory Failure Registry (n = 412) as having received extracorporeal membrane oxygenation (ECMO) for severe respiratory syncytial virus infection with pulmonary failure. Forty-nine percent (26/53) were successfully managed and survived to hospital discharge. The mean patient age was 5.0 +/- 8.6 months. Duration of mechanical ventilation before institution of extracorporeal life support was 8.1 +/- 6.2 days. Multivariate logistic regression analysis found four variables to be associated with patient nonsurvival at the p < 0.05 level: male gender, longer duration of mechanical ventilation before ECMO, higher peak inspiratory pressure, and lower ratio of arterial oxygen tension to fraction of inspired oxygen. Era of treatment was not associated with outcome. Receiver operator characteristic curve analysis of this multivariate model resulted in cutoff points of r = 0.5 and 0.1 that resulted in 92% sensitivity and 81% specificity (false-positive ratio 19%) and 96% sensitivity and 73% specificity (false-positive ratio 27%), respectively. CONCLUSIONS: Predictors of outcome of severe respiratory failure caused by respiratory syncytial virus infection managed with ECMO exist, and multivariate predictive models with high sensitivity and low false-positive risk are possible. Similar mathematical models may be helpful in establishing criteria for future trials of ECMO versus conventional respiratory support.

Unsuspected congenital heart disease in neonates receiving extracorporeal life support: a review of ninety-five cases from the Extracorporeal Life Support Organization Registry.

The purpose of this study was to determine the frequency of patients with congenital heart disease who were given extracorporeal life support (ECLS) for respiratory failure. Underlying congenital heart disease "masked" by respiratory failure occurred in 2%. The most frequent pre-ECLS diagnosis that "masked" congenital heart disease was persistent fetal circulation. Of neonates with a pre-ECLS diagnosis of persistent fetal circulation, congenital heart disease was found in 56 (9%) of 623 patients.

Effects of supplemental oxygen administration in an infant with pulmonary artery hypertension.

In patients with pulmonary disease, pulmonary artery hypertension often occurs as a result of pulmonary artery vasoconstriction, primarily from hypoxia and alveolar hypotension. In this report we describe the hemodynamic effects of breathing supplemental oxygen in a child with bronchopulmonary dysplasia and pulmonary artery hypertension. These hemodynamic effects include an improvement in oxygenation, an increase in systemic vascular resistance, and a decrease in the pulmonary vascular resistance. As a direct result of these changes in vascular resistances, alterations of heart rate, cardiac index, stroke volume, aortic pressure, oxygen consumption, and pulmonary artery pressure have been shown to occur. Oxygen is widely used to treat many physiologic conditions. However, during the administration of supplemental oxygen, rarely do we recognize the hemodynamic changes associated with its use. These hemodynamic effects must be clearly understood and appreciated before oxygen administration in any clinical situation.

Damage to physicians' gloves during "routine" cardiac catheterization: an underappreciated occurrence.

Recently, concern for the protection of health care employees and health care recipients has led to increasing awareness of transmitted infections. However, it is evident that damage of barrier methods of controlling infection can occur and go undetected. In a prospective study conducted from January 13, 1989 through February 15, 1989, 100 sequential pairs of gloves (200 gloves) worn during routine pediatric cardiac catheterizations were evaluated for punctures. A control group of 25 pairs of unused physicians' gloves was also evaluated for the presence of spontaneous leakage. In the 25 pairs of unused gloves (50 gloves), no punctures were detected, whereas in the 200 gloves worn during the catheterization procedures, punctures were found in 38 gloves or 19% (p less than 0.001). When comparing the frequency of punctures with respect to the digits, 81% of the punctures were detected within the thumb and index finger of the gloves. In the majority of instances, physicians describe stopcock manipulation as the cause of the punctures. Implication of the stopcock as a possible mechanism for glove damage can be isolated to the stop mechanism on the stopcock pivot. Although surgeons' gloves are worn in many procedures besides surgery, no previous studies have defined the incidence of glove punctures during these procedures. Recommendations include a redesign of the stopcock as a protective measure and immediate change of latex surgeons' gloves whenever damage is suspected.