Extracorporeal life support for neonatal respiratory failure. A 20-year experience

Premature and Extracorporeal Life Support: Is it Time? A Systematic Review

Early preterm birth < 34 gestational weeks (GA) and birth weight (BW) <2 kg are relative contraindications for extracorporeal membrane oxygenation (ECMO). However, with improved technology, ECMO is presently managed more safely and with decreasing complications. Thus, these relative contraindications may no longer apply. We performed a systematic review to evaluate the existing literature on ECMO in early and late (34-37 GA) prematurity focusing on survival to hospital discharge and the complication intracranial hemorrhage (ICH). Data sources: MEDLINE, PubMed, Web of Science, Embase, and the Cochrane Database. Only publications in the English language were evaluated. Of the 36 included studies, 23 were related to ECMO support for respiratory failure, 10 for cardiac causes, and four for congenital diaphragmatic hernia (CDH). Over the past decades, the frequency of ICH has declined (89-21%); survival has increased in both early prematurity (25-76%), and in CDH (33-75%), with outcome similar to late prematurity (48%). The study was limited by an inherent risk of bias from overlapping single-center and registry data. Both the risk of ICH and death have decreased in prematurely born treated with ECMO. We challenge the 34 week GA time limit for ECMO and propose an international task force to revise current guidelines. At present, gestational age < 34 weeks might no longer be considered a contraindication for ECMO in premature neonates.

Conversion from Venovenous to Venoarterial Extracorporeal Membrane Oxygenation in Adults

No major study has been performed on the conversion from venovenous (VV) to venoarterial (VA) extracorporeal membrane oxygenation (ECMO) in adults. This single-center retrospective cohort study aimed to investigate the incidence, indication, and outcome in patients who converted from VV to VA ECMO. All adult patients (≥18 years) who commenced VV ECMO at our center between 2005 and 2018 were screened. Of 219 VV ECMO patients, 21% (n = 46) were converted to VA ECMO. The indications for conversion were right ventricular failure (RVF) (65%), cardiogenic shock (26%), and other (9%). In the converted patients, there was a significant increase in Sequential Organ Failure Assessment (SOFA) scores between admission 12 (9-13) and conversion 15 (13-17, p < 0.001). Compared to non-converted patients, converted patients also had a higher mortality rate (62% vs. 16%, p < 0.001) and a lower admission Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) score (p < 0.001). Outcomes were especially unfavorable in those converted due to RVF. These results indicate that VA ECMO, as opposed to VV ECMO, should be considered as the first mode of choice in patients with respiratory failure and signs of circulatory impairment, especially in those with impaired RV function. For the remaining patients, Pre-admission RESP score, daily echocardiography, and SOFA score trajectories may help in the early identification of those where conversion from VV to VA ECMO is warranted. Multi-centric studies are warranted to validate these findings.

Nosocomial Infections During Extracorporeal Membrane Oxygenation in Neonatal, Pediatric, and Adult Patients: A Comprehensive Narrative Review

OBJECTIVES

Extracorporeal membrane oxygenation is increasingly used in critically ill patients with refractory cardiopulmonary failure. Nosocomial infection acquired during extracorporeal membrane oxygenation represents one of the most frequent complications but the available evidence on the risk of infection and its association with outcomes has not been comprehensively analyzed. We performed a narrative review examining the epidemiology of nosocomial infection during extracorporeal membrane oxygenation, association with clinical outcomes, and preventive strategies.

DATA SOURCES

We searched PubMed, Web of Science, EMBASE, and the Cochrane Library between 1972 and June 2018.

STUDY SELECTION

We included any article which detailed nosocomial infection during extracorporeal membrane oxygenation. Articles were excluded if they were not written in English, detailed extracorporeal membrane oxygenation use for infections acquired prior to extracorporeal membrane oxygenation, or used other forms of extracorporeal support such as ventricular assist devices.

DATA EXTRACTION

Two reviewers independently assessed eligibility and extracted data. We screened 984 abstracts and included 59 articles in the final review.

DATA SYNTHESIS

The reported risk of nosocomial infection among patients receiving extracorporeal membrane oxygenation ranged from 3.5% to 64% per extracorporeal membrane oxygenation run, while the incidence of infection ranged from 10.1 to 116.2/1,000 extracorporeal membrane oxygenation days. Nosocomial infections during extracorporeal membrane oxygenation were consistently associated with longer duration of extracorporeal membrane oxygenation and, in several large multicenter studies, with increased mortality. Risk factors for nosocomial infection included duration of extracorporeal membrane oxygenation, mechanical and hemorrhagic complications on extracorporeal membrane oxygenation, and use of venoarterial and central extracorporeal membrane oxygenation. Biomarkers had low specificity for infection in this population. Few studies examined strategies on how to prevent nosocomial infection on extracorporeal membrane oxygenation.

CONCLUSIONS

Nosocomial infections in extracorporeal membrane oxygenation patients are common and associated with worse outcomes. There is substantial variation in the rates of reported infection, and thus, it is possible that some may be preventable. The evidence for current diagnostic, preventive, and therapeutic strategies for infection during extracorporeal membrane oxygenation is limited and requires further investigation.

Incidence of nosocomial infections in adult patients undergoing extracorporeal membrane oxygenation

INTRODUCTION

Critically ill patients requiring extracorporeal membrane oxygenation (ECMO) are at increased risk for developing nosocomial infections owing to their underlying disease process along with numerous invasive monitoring devices.

METHODS

We retrospectively analyzed the rate, type, pathogens, outcomes, and risk factors of nosocomial infections that developed during adult patients on ECMO at our institution from 2012-2015.

RESULTS

Compared to current ELSO reported adult nosocomial infections rate of 20.5%, we report our rate of 26% (CI 17.2%-34.7%). No significant differences were observed in mortality (42.3% vs. 36.5%; p=0.598), and presence of either antibiotics prior to ECMO (57.7% vs. 56.7%; p=0.934) or culture-proven infection prior to ECMO (19.2% vs. 32.4%; p=0.201). Patients who developed nosocomial infections had longer duration of ECMO (13 vs. 5 days; p<0.001), longer length of stay (36.5 vs. 18.5 days; p=0.004), and more days on ventilator (29 vs. 12.5; p=0.002). Duration of ECMO (OR=1.20, 95% CI 1.02-1.39; p=0.020) and duration of ECMO greater than 10 days (OR=14.65, 95% CI 1.81-118.78; p=0.012) were independent risk factors for developing nosocomial infections. However, there was no difference in mortality when duration of ECMO >10 days was compared with ≤10 days (28.5% vs. 43.1%; p=0.154).

CONCLUSION

Nosocomial infections have no effect on survival in adult ECMO patients. Presence of either antibiotics or infection prior to ECMO has no effect on developing nosocomial infections while on ECMO. Duration of ECMO longer than 10 days is a major risk factor for developing nosocomial infection.

Normothermic Ex Vivo Heart Perfusion: Effects of Live Animal Blood and Plasma Cross Circulation

Prolonged normothermic ex vivo heart perfusion could transform cardiac transplantation. To help identify perfusate components that might enable long-term perfusion, we evaluated the effects of cross-circulated whole blood and cross-circulated plasma from a live paracorporeal animal on donor porcine hearts preserved via normothermic ex vivo heart perfusion. Standard perfusion (SP; n = 40) utilized red blood cell/plasma perfusate and Langendorff technique for a goal of 12 hours. Cross-circulation groups used a similar circuit with the addition of cross-circulated venous whole blood (XC-blood; n = 6) or cross-circulated filtered plasma (XC-plasma; n = 7) between a live paracorporeal pig under anesthesia and the perfusate reservoir. Data included oxygen metabolism, vascular resistance, lactate production, left ventricular function, myocardial electrical impedance, and histopathologic injury score. All cross-circulation hearts were successfully perfused for 12 hours, compared with 22 of 40 SP hearts (55%; p = 0.002). Both cross-circulation groups demonstrated higher oxygen consumption and vascular resistance than standard hearts from hours 3-12. No significant differences were seen between XC-blood and XC-plasma hearts in any variable, including left ventricular dP/dT after 12 hours (1478 ± 700 mm Hg/s vs. 872 ± 500; p = 0.17). We conclude that cross circulation of whole blood or plasma from a live animal improves preservation of function of perfused hearts, and cross-circulated plasma performs similarly to cross-circulated whole blood.

Predictors of intracranial hemorrhage in adult patients on extracorporeal membrane oxygenation: an observational cohort study

BACKGROUND

Intracranial hemorrhage (ICH) is a recognized complication of adults treated with extracorporeal membrane oxygenation (ECMO) and is associated with increased morbidity and mortality. However, the predictors of ICH in this patient category are poorly understood. The purpose of this study was to identify predictors of ICH in ECMO-treated adult patients.

METHODS

We conducted a retrospective review of adult patients (≥18 years) treated with ECMO at the Karolinska University Hospital (Stockholm, Sweden) between September 2005 and June 2016, excluding patients with ICH upon admission or those who were treated with ECMO for less than 12 h. In a comparative analysis, the primary end-points were the difference in baseline characteristics and predictors of hemorrhage occurrence (ICH vs. non-ICH cohorts). The secondary end-point was difference in mortality between groups. Paired testing and uni- and multivariate regression models were applied.

RESULTS

Two hundred and fifty-three patients were included, of which 54 (21%) experienced an ICH during ECMO treatment. The mortality for patients with ICH was 81% at 1 month and 85% at 6 months, respectively, compared to 28 and 33% in patients who did not develop ICH. When comparing ICH vs. non-ICH cohorts, pre-admission antithrombotic therapy (p = 0.018), high pre-cannulation Sepsis-related Organ Failure Assessment (SOFA) coagulation score (p = 0.015), low platelet count (p < 0.001), and spontaneous extracranial hemorrhage (p = 0.045) were predictors of ICH. In a multivariate regression model predicting ICH, pre-admission antithrombotic therapy and low platelet count demonstrated independent risk association. When comparing the temporal trajectories for coagulation variables in the days leading up to the detection of an ICH, plasma antithrombin significantly increased per patient over time (p = 0.014). No other temporal trajectories were found.

CONCLUSIONS

ICH in adult ECMO patients is associated with a high mortality rate and independently associated with pre-admission antithrombotic therapy and low platelet count, thus highlighting important areas of potential treatment strategies to prevent ICH development.

Association of Hospital Structure and Complications With Mortality After Pediatric Extracorporeal Membrane Oxygenation

OBJECTIVES

Extracorporeal membrane oxygenation is increasingly utilized to provide cardiopulmonary support to critically ill children. Although life-saving in many instances, extracorporeal membrane oxygenation support is associated with considerable morbidity and mortality. This study evaluates the effect of extracorporeal membrane oxygenation complications and extracorporeal membrane oxygenation hospital characteristics on mortality in neonates and children supported with extracorporeal membrane oxygenation.

DESIGN

Retrospective analysis of administrative data.

SETTING

Data from 31 U.S. states included in 2012 Healthcare Cost and Utilization Project Kids' Inpatient Database.

PATIENTS

Children treated with extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Study subject were identified using International Classification of Diseases, 9th Edition Clinical Modification code 39.65 and classified into six diagnostic categories: 1) cardiac surgery, 2) non-surgical heart disease, 3) congenital diaphragmatic hernia, 4) neonatal respiratory failure, 5) pediatric respiratory failure, and 6) sepsis. Demographics, hospital characteristics, and outcome information were used in a multivariate logistic regression analysis to determine factors associated with mortality. We identified 1,465 children treated with extracorporeal membrane oxygenation. Overall mortality was 40% (591/1,465). Mortality was independently associated with diagnosis (heart disease: odds ratio, 1.7; p = 0.01; congenital diaphragmatic hernia: odds ratio, 5.1; p < 0.001; and sepsis odds ratio: 2.4; p = 0.003 compared with neonatal respiratory failure) time from hospital admission to extracorporeal membrane oxygenation of more than 10 days (odds ratio, 4.5; p < 0.001) and extracorporeal membrane oxygenation complications (renal [odds ratio: 5; p < 0.001] and neurologic [odds ratio, 1.4; p = 0.03] injury). In addition, hospitals with bed size less than 400 had higher mortality (odds ratio, 1.4; p = 0.02). In patients with any extracorporeal membrane oxygenation complication, probability of mortality was lower for extracorporeal membrane oxygenation patients in larger hospitals, 38% (95% CI, 37-39) versus 44% (95% CI, 43-46) with p value of less than 0.001.

CONCLUSIONS

Extracorporeal membrane oxygenation mortality was significantly associated with patient diagnosis, time to extracorporeal membrane oxygenation initiation, extracorporeal membrane oxygenation complications, and extracorporeal membrane oxygenation hospital bed size. Improved survival in larger hospitals supports centralization of extracorporeal membrane oxygenation services to larger centers.

Hospital Costs for Neonates and Children Supported with Extracorporeal Membrane Oxygenation

OBJECTIVE

To assess the characteristics associated with high hospital cost for patients receiving extracorporeal membrane oxygenation (ECMO) to identify a cohort of high-resource users.

STUDY DESIGN

Cost for hospitalization, during which ECMO support was used, was calculated from hospital charges reported in the 2012 Health Care Cost and Use Project Kid's Inpatient Database. Patients were categorized into 6 diagnostic groups: (1) cardiac surgery; (2) nonsurgical heart disease; (3) congenital diaphragmatic hernia; (4) neonatal respiratory failure; (5) pediatric respiratory failure; and (6) sepsis. We categorized cost into 4 groups based on quartiles. We compared ECMO cost with hospital cost for bone marrow, liver, and kidney transplants performed during the same year.

RESULTS

Median hospital cost for children supported with ECMO (n = 1465) was $230,425 (IQR: $126,599-$420,960). In a multivariable model, lower cost was associated with neonatal respiratory failure (OR: 0.19) and sepsis (OR 0.53) compared with cardiac surgery (OR: 1.88), whereas greater cost was associated with smaller hospital bed-size <99 (OR: 3.49) and 100-399 beds (OR: 3.03) compared with hospitals >400 beds, hospital location (Midwest [OR: 1.74] and West [OR 2.18] compared with North-East), and complications such as renal failure (OR: 3.77) and thromboembolic complications (OR 1.60). Hospital cost per survivor was greater for ECMO ($519,450) than bone marrow transplantation ($207,212), liver ($231,755), or kidney transplantation ($82,008) groups.

CONCLUSIONS

Hospitalization cost for children supported with ECMO is high. Diagnosis, hospital characteristics, and presence of complications are associated with increased cost.

Trends in U.S. Extracorporeal Membrane Oxygenation Use and Outcomes: 2002-2012

This study evaluates contemporary trends in the use and outcomes of adult patients undergoing extracorporeal membrane oxygenation (ECMO) in U.S. hospitals. All adult discharges in the Nationwide Inpatient Sample database during the years 2002-2012 that included ECMO were used to estimate the total number of U.S. ECMO hospitalizations (n = 12,407). Diagnostic codes were used to group patients by indication for ECMO use into postcardiotomy, heart transplant, lung transplant, cardiogenic shock, respiratory failure, and cardiopulmonary failure. A Mann-Kendall test was used to examine trends over time using standard statistical techniques for survey data. We found that ECMO use increased significantly from 2002-2012 (P = 0.003), whereas in-hospital mortality rate fluctuated without a significant difference in trend over time. No significant trend was observed in overall ECMO use from 2002-2007, but the use did demonstrate a statistically significant increase from 2007-2012 (P = 0.0028). The highest in-hospital mortality rates were found in the postcardiotomy (57.2%) and respiratory failure (59.2%) groups. Lung and heart transplant groups had the lowest in-hospital mortality rates (44.10% and 45.31%, respectively). The proportion of ECMO use for postcardiotomy decreased from 56.9% in 2002 to 37.9% in 2012 (P = 0.026) and increased for cardiopulmonary failure from 3.9% to 11.1% (P = 0.026). We concluded that ECMO use in the United States increased between 2002 and 2012, driven primarily by increase in national ECMO use beginning in 2007. Mortality rates remained high but stable during this time period. Though there were shifts in relative ECMO use among patient groups, absolute ECMO use increased for all indications over the study period.

Extracorporeal membranous oxygenation (ECMO) in polytrauma: what the radiologist needs to know

The purpose of this article is to review the spectrum of severe traumatic injuries treatable with ECMO and their imaging features, considerations for cannula placement, and complications that may arise in polytraumatized patients on extracorporeal life support. Recent major advances in miniaturization and biocompatibility of ECMO devices have dramatically increased their safety profile and expanded the application of ECMO to patients with severe polytrauma.

The impact of ethnic population dynamics on neonatal ECMO outcomes: a single urban institutional study

INTRODUCTION

Neonatal extracorporeal membrane oxygenation ECMO has been clinically used for the last 25 y. It has been an effective tool for both cardiac and non cardiac conditions. The impact of ethno-demographic changes on ECMO outcomes however remains unknown. We evaluated a single institution's experience with non cardiac neonatal ECMO over a 28-y period.

METHODS

A retrospective review of all neonates undergoing noncardiac ECMO between the y 1984 and 2011 was conducted and stratified into year groups I, II, III (≤1990, 1991-2000, and ≥2001). Demographic, clinical, and outcome data were collected. The patient specifics, ECMO type, ECMO length, blood use, complications, and outcomes were analyzed. Univariate, bivariate, and multivariate analyses were then performed.

RESULTS

Data was available for 827 patients. The number of African-American and Hispanic patients increased over the last 27 y (27.5% versus 45.0% and 3.3% versus 21.5%, year group I versus year group III, respectively). The proportion of congenital diaphragmatic hernia (CDH) patients by ethnicity also increased for African-Americans and Hispanics between the two year groups (22.0% to 33.0% and 4.9% to 33.0%, respectively). Similar pattern was noted for non-CDH diagnoses. Low birth weight, low APGAR scores, CDH, primary pulmonary hypertension, central nervous system hemorrhage, and ECMO were independent predictors of mortality. Ethnicity, in itself however, was not associated with mortality on adjusted analysis.

CONCLUSION

More African-Americans and Hispanics have required ECMO over the years with a concurrent decrease in the number of Caucasians. While ethnicity was not an independent predictor of mortality, it appears to be a surrogate for fatal but sometime preventable diagnoses among minorities. Further investigations are needed to better delineate the reason behind this disparity.

Extracorporeal life support: utilization, cost, controversy, and ethics of trying to save lives

Since the first successful application of extracorporeal membrane oxygenation (ECMO) in 1972, ECMO's role in the management of respiratory and circulatory collapse continues to be refined and debated. Randomized clinical trials aimed at establishing efficacy and patient selection criteria have been fraught with ethical challenges. Growing concerns over rising health care costs require that careful evaluations of cost, utilization, and ethical issues surrounding heroic life-saving interventions such as ECMO are undertaken. Continued analyses of ECMO's place in the medical management of respiratory and circulatory failure will help ensure that ECMO is used for not only prolonging life but also for providing a chance for "quality of life" following recovery from near-fatal illnesses.

Extracorporeal membrane oxygenation: current clinical practice, coding, and reimbursement

Extracorporeal membrane oxygenation (ECMO) is a technique for providing life support for patients experiencing both pulmonary and cardiac failure by maintaining oxygenation and perfusion until native organ function is restored. ECMO is used routinely at many specialized hospitals for infants and less commonly for children with respiratory or cardiac failure from a variety of causes. Its usage is more controversial in adults, but select medical centers have reported favorable findings in patients with ARDS and other causes of severe pulmonary failure. ECMO is also rarely used as a rescue therapy in a small subset of adult patients with cardiac failure. This article will review the current uses and techniques of ECMO in the critical care setting as well as the evidence supporting its usage. In addition, current practice management related to coding and reimbursement for this intensive therapy will be discussed.

Application of ECMO in multitrauma patients with ARDS as rescue therapy

BACKGROUND

Despite recent advances in critical care management, the mortality of acute respiratory distress syndrome (ARDS) remains high. The final rescue therapy for patients with severe hypoxia refractory to conventional therapy modalities is the extracorporeal gas exchange.

METHODS

We report the management of three polytraumatized patients with life-threatening injuries, severe blunt thoracic trauma, and consecutive ARDS treating by extracorporeal membrane oxygenation (ECMO). Two patients suffered a car accident with severe lung contusion and parenychmal bleeding. Bronchial rupture and mediastinal emphysema was found in one of them. Another patient developed ARDS after attempted suicide with multiple fractures together with blunt abdominal and thoracic trauma.

RESULTS

All patients were placed on ECMO and could be rapidly stabilized. They were weaned from ECMO after a mean of 114 +/- 27 hours of support without complications, respectively. Mean duration of ICU stay was 37 +/- 23 days.

CONCLUSIONS

Quick encouragement of ECMO for the temporary management of gas exchange may increase survival rates in trauma patients with ARDS.

Potential drug sequestration during extracorporeal membrane oxygenation: results from an ex vivo experiment

OBJECTIVE

Using an ex vivo simulation model we set out to estimate the amount of drug lost due to sequestration within the extracorporeal circuit over time.

DESIGN

Simulated closed-loop extracorporeal membrane oxygenation (ECMO) circuits were prepared using a 1.5-m2 silicone membrane oxygenator. Group A consisted of heparin, dopamine, ampicillin, vancomycin, phenobarbital and fentanyl. Group B consisted of epinephrine, cefazolin, hydrocortisone, fosphenytoin and morphine. Drugs were tested in crystalloid and blood-primed circuits. After administration of a one-time dose of drugs in the priming fluid, baseline drug concentrations were obtained (P0). A simultaneous specimen was stored for stability testing at 24 h (P4). Serial post-membrane drug concentrations were then obtained at 30 min (P1), 3 h (P2) and 24 h (P3) from circuit fluid.

MEASUREMENTS AND RESULTS

One hundred and one samples were analyzed. At the end of 24 h in crystalloid-primed circuits, 71.8% of ampicillin, 96.7% of epinephrine, 17.6% of fosphenytoin, 33.3% of heparin, 17.5% of morphine and 87% of fentanyl was lost. At the end of 24 h in blood-primed extracorporeal circuits, 15.4% of ampicillin, 21% of cefazolin, 71% of voriconazole, 31.4% of fosphenytoin, 53.3% of heparin and 100% of fentanyl was lost. There was a significant decrease in overall drug concentrations from 30 min to 24 h for both crystalloid-primed circuits (p = 0.023) and blood-primed circuits (p = 0.04).

CONCLUSIONS

Our ex vivo study demonstrates serial losses of several drugs commonly used during ECMO therapy. Therapeutic concentrations of fentanyl, voriconazole, antimicrobials and heparin cannot be guaranteed in patients on ECMO.

Extracorporeal Life Support for Massive Pulmonary Embolism

BACKGROUND

Massive pulmonary embolism is frequently lethal because of acute irreversible pulmonary and cardiac failure. Extracorporeal life support (ECLS) has been used for cardiopulmonary failure in our institution since 1988, and we reviewed our experience with its use in the management of massive pulmonary emboli.

METHODS

We reviewed our complete experience with ECLS for massive pulmonary emboli from January 1992 through December 2005. The records of 21 patients were examined and data extracted.

RESULTS

During the study period, 21 patients received ECLS for massive pulmonary emboli. All patients were on vasoactive drugs, acidemic, and hypoxic at the time of institution of ECLS. Eight were in active cardiac arrest. Five were trauma patients, eight had recently undergone an operation, and six had a hypercoagulable disorder. Nineteen of the 21 patients were cannulated for venoarterial bypass and two were placed on venovenous bypass. The average duration of support for survivors was 5.4 days, ranging from 5 hours to 12.5 days. Emboli resolved with anticoagulation in 10 of 13 survivors and 4 of 13 survivors underwent surgical pulmonary embolectomy. Catastrophic neurologic events were the most common cause of mortality in our series; four patients died from intracranial hemorrhage. The overall survival rate was 62% (13/21).

CONCLUSIONS

We conclude that emergent ECLS provides an opportunity to improve the prognosis of an otherwise near-fatal condition, and should be considered in the algorithm for management of a massive pulmonary embolism in an unstable patient.

Pulsatile ECMO in Neonates and Infants: First European Clinical Experience with a New Device

This study presents the first European clinical experience with the Medos DeltaStream DP1, a new pulsatile flow pump, in neonates and infants. Between January 2002 and December 2004, 420 patients at our institution underwent congenital heart surgery on cardiopulmonary bypass. During this period, 10 patients required extracorporeal membrane oxygenation (ECMO) support for acute postcardiotomy heart failure. Seven patients (median age 7 days, range 1-70 days), were supported by a nonpulsatile Biomedicus centrifugal pump, whereas three patients (aged 1 month, 1 year, and 12 years) were supported by a pulsatile Medos DP1. The DP1 is an extracorporeal rotary blood pump. The pump features a diagonal-flow impeller, and can be used for both continuous and pulsatile output. Special characteristics include a small priming volume of approximately 30 ml and a high pumping capacity. A temperature sensor and speed sensors are integrated in the pump. The pump has a delivery rate of up to 8 l/min and a speed range of 100-10,000 rpm. Overall mortality was 40% (4 of 10 patients), and all four deaths were in the nonpulsatile Biomedicus group. In the nonpulsatile group, the median support duration was 95 hours with a range of 48-140 hours. Two patients assisted with the pulsatile pump system were successfully weaned after 36 and 53 hours, respectively; the 12-year-old patient was successfully transplanted on the eighth postimplant day and discharged from the hospital on the 32nd posttransplant day. Although this preliminary experience doesn't allow for statistical analysis, clinically it was possible to observe a better performance in pulsatile flow recipients with faster lactate recovery, reduced need for inotropic support, reduced assistance duration in bridge-to-recovery settings, and smoother intensive care management. ECMO for postcardiotomy heart failure in neonates and infants still carries high mortality and morbidity rates. Pulsatile flow with the Medos DeltaStream DP1 pump system improves results by producing more physiologic hemodynamics, reducing the duration of support in the case of bridge to recovery, and improving end-organ function.

Increased parathyroid hormone and decreased calcitriol during neonatal extracorporeal membrane oxygenation

OBJECTIVE

We noted that age-related normal calcium doses in neonates on venoarterial extracorporeal membrane oxygenation result in hypercalcemia. To avoid hypercalcemia and its potential consequences these infants are given one-half the normal calcium dose. We studied the pathogenesis of hypercalcemia and hypomagnesemia by evaluating calcitriol, intact parathyroid hormone, and calcitonin status during extracorporeal membrane oxygenation.

DESIGN AND SETTING

Prospective, observational study in the intensive care unit of a 225-bed tertiary care pediatric hospital.

PATIENTS AND PARTICIPANTS

Twelve neonates under 7 days old with severe pulmonary disease requiring extracorporeal membrane oxygenation.

MEASUREMENTS AND RESULTS

Blood was obtained for intact parathyroid hormone and calcitriol concentrations before cannulation, during (extracorporeal membrane oxygenation days 2, 4, and predecannulation in those on >6 days), and after decannulation on days 1 and 3. Calcitonin concentrations were measured before cannulation, during, and after decannulation in the last seven patients. Prior to cannulation parathyroid hormone was normal (1.4-5.7 pmol/l) and on day 2 increased to 7.8+/-8.4 pmol/l. Before cannulation calcitriol was 14.5+/-8.21 pmol/l (normal 41-143 pmol/l), and concentrations remained low until after decannulation. In three of the seven infants calcitonin concentrations (normal <73 ng/l) were above the upper limit of the assay (>1150 ng/l) prior to cannulation and during extracorporeal membrane oxygenation.

CONCLUSIONS

Regulation of the vitamin D-endocrine system during neonatal venoarterial extracorporeal membrane oxygenation appears to be aberrant compared to normal vitamin D-endocrine system regulation. The pathogenesis of this abnormality remains unclear and requires further study.

Venovenous extracorporeal membrane oxygenation for respiratory failure in inotrope dependent neonates

It is often stated that venovenous extracorporeal membrane oxygenation (VV ECMO) should not be used in inotrope dependent patients. It is our practice to use VV ECMO in most patients with respiratory failure even though many of these patients are receiving significant doses of inotropes. Our objective was to review the mode of ECMO in relation to precannulation doses of inotropes administered to neonates treated with ECMO for respiratory failure. Forty-three consecutive case notes were reviewed. Data were collected for basic demographic and ECMO parameters. Inotropic doses were converted to a single score for ease of comparison, with one point equivalent to 1 microg/kg/min dopamine. Forty-three neonates were studied; 37(86%) were treated with VV ECMO and 6 (14%) were treated with VA ECMO. Significant pre-ECMO inotropic support (score > 10) was present in 30 (70%) of the 43 cases. Of these patients, 26 were treated via VV ECMO with a survival rate of 84%, while 4 were treated with VA ECMO with a survival of 75%. Inotrope scores fell to nonsignificant levels (< 10) within 24 hours, regardless of ECMO mode. Mean arterial blood pressure remained above precannulation levels in both groups. VV ECMO allows safe treatment of neonatal respiratory failure in the presence of significant inotropic support. We recommend VV ECMO for neonatal respiratory failure in all cases except where double lumen cannulation is impossible or when septic shock is refractory to inotropic support (i.e., mean blood pressure < 35 mm Hg despite inotrope score of > 100).

Development of disposable self-regulating blood pumps and automatically-controlled portable extracorporeal membrane oxygenation systems for neonatal extracorporeal membrane oxygenation

For safer and simpler neonatal ECMO management, the authors have been developing an innovative, automatically-controlled ECMO machine using self-regulating blood pumps. The newest model is an air-driven, tube-type blood pump. A pair of blood pumps are placed in parallel and actuated alternately with compressed air. The pump flow is automatically regulated in accordance with hemodynamic changes of the body. The need for a venous reservoir is eliminated because the circuit does not generate excessive negative pressure when there are shortages of draining blood. Therefore, the priming volume of the circuit is only 85 ml. This ECMO apparatus has three driving modes, one of which is a "delay" mode. This enables the pump flow to easily be varied from 10 to 500 ml/min under automatic control, and it can be used when the pump flow is decreased for weaning. This newest ECMO apparatus was clinically used in 3 neonates with severe lung hypoplasia and persistent fetal circulation. The ECMO duration was 139 h to 168 h, and the maximum ECMO flow 71.3 to 109.0 ml/min/kg. Thanks to the self-regulation, intensive observation of the circuit was not necessary during ECMO. Damage to blood cells was less significant, and the use of blood products was only minimal (15.7 ml/kg/day) because a large volume of blood to stabilize the pump performance was not necessary. In conclusion, the automatically-controlled ECMO apparatus worked well without complications by changing the ECMO flow automatically in accordance with hemodynamic changes. This automatic ECMO system required fewer personnel expenditures and was also favorable in terms of hematological findings.

Mechanical support of the pediatric cardiac patient

Increased understanding of the anatomical nuances of congenital heart defects, improved methods of myocardial preservation, and advances in surgical techniques have led to improved results and need for postoperative mechanical support in patients undergoing congenital heart surgery. However, there remains a small portion of patients with myocardial or pulmonary failure that can can be rescued by intelligent use of mechanical support. The most widely used form of mechanical support is extracorporeal membrane oxygenation (ECMO), which has been adapted for use in congenital heart patients as well as patients with respiratory failure. Recent reports have suggested that ventricular support devices may also be useful in this patient population. A promising new application of mechanical support is for rescue during cardiac arrest; surprisingly good results have been obtained in this obviously moribund group of patients. Future developments in mechanical support include more accurate identification of patients who will benefit from this therapy and technological advances that will provide greater biocompatibility and simplification of the support circuit. Copyright 2000 by W.B. Saunders Company

New trends in extracorporeal membrane oxygenation in newborn pulmonary diseases

New trends in extracorporeal membrane oxygenation (ECMO) for respiratory failure in the newborn were reviewed. Following a decade of clinical research, ECMO is now the standard treatment for newborn respiratory failure when all other conventional less-invasive treatment options have been exhausted. As of July 2000, 15,525 newborns with respiratory failure treated with ECMO have been entered into the registry of the Extracorporeal Life Support Organization with an overall survival rate of 78%. The latest improvement in ECMO technology in this group of patients includes minimally invasive modes of vascular access through percutaneous approaches to minimize morbidity. However, with advances in modes of mechanical ventilation, including high-frequency ventilation and the introduction of inhaled nitric oxide, the use and necessity for ECMO have clearly diminished for newborn respiratory failure.

Application of extracorporeal membrane oxygenation in adult burn patients

Adult respiratory distress syndrome (ARDS) has been the major cause of mortality in burn injury. The authors reported the experience of using extracorporeal membrane oxygenation (ECMO) to treat adult burn patient with ARDS. Three patients with burn or electric injury, around 48.9% of body surface area over second-degree burns, developed ARDS after resuscitation. All had positive blood culture and depended on a ventilator more than 5 days before ECMO. Venovenous (VV) ECMO was started at the beginning of severe respiratory failure with an oxygen index of 61.6 +/- 15.5 cm H2O/mm Hg (> or =40 cm H2O/mm Hg), partial arterial oxygen tension to inspired oxygen fraction (Pa(O2)/Fi(O2)) of 46.1 +/- 7.0 mm Hg (< or =200 mm Hg), positive end expiratory pressure (PEEP) of 15.7 +/- 1.6 cm H2O (> or =10 cm H2O), alveolar-arterial difference in oxygen concentration (A-a D(O2)) of 618.9 +/- 19.3 mm Hg (> or =300 mm Hg), and lung compliance of 17.3 +/- 4.6 ml/cm H2O (< or =30 ml/cm H2O). The VV type had to be converted to the newly designed veno-venoarterial (V-VA) ECMO due to the myocardial dysfunction. Two of three patients survived. The duration of ECMO was 160.2 +/- 51.1 h. Two patients received debridement of escar during ECMO support and desmopressin infusion, and no increased bleeding or coagulopathy was found. The respiratory parameters were significantly improved after ECMO, especially in the survivors. ECMO is also suitable for ARDS in adult burn injury.

Hypercalcemia associated with extracorporeal life support in neonates

BACKGROUND/PURPOSE

Disturbances in calcium homeostasis are common at initiation of extracorporeal life support (ECLS). At the authors' institution many neonates undergoing ECLS have developed hypercalcemia. To determine the frequency of hypercalcemia in neonates during ECLS we performed retrospective chart review of neonates that required ECLS at our neonatal intensive care unit.

METHODS

The authors identified 76 consecutive neonates who underwent ECLS before 10 days of age at Cincinnati Children's Hospital Medical Center from July 1, 1991 to June 30, 1996. The hospital charts and ELSO forms were reviewed. Demographic, clinical, and laboratory data for each of the patients were reviewed, both before initiation and during ECLS. Hypercalcemia was defined as total serum calcium concentration of greater than 11 mg/dL (2.74 mmol/L) on at least one occasion beyond the first 24 hours of ECLS.

RESULTS

The hospital charts and ELSO forms from 70 patients were available for review. One patient was excluded because he was only on ECLS for 33 hours, and there were no calcium levels obtained after 24 hours of ECLS and until death. Twenty-five (36%) neonates undergoing ECLS had hypercalcemia (serum Ca > 11 mg/dL [2.74 mmol/L]). Hypercalcemia was associated with longer duration of ECLS (hypercalcemia group, 243 +/- 115 hours and normocalcemia group, 139 +/- 64 hours) and greater requirements for platelet transfusions (hypercalcemia group, 538 +/- 282 mL and normocalcemia group, 372 +/- 233 mL). This could not be explained by differences in primary diagnosis, amounts of calcium administered, and acid-base status.

CONCLUSIONS

Hypercalcemia was found to be common in neonates that require ECLS and is associated with longer duration of ECLS support. Conservative calcium administration for neonates while on ECLS may be warranted.

Heparin bonding of the extracorporeal circuit reduces thrombosis during prolonged lung assist in goats

This study investigated whether an artificial membrane lung of nonmicroporous polyolefin hollow fibers bonded with heparin could prolong venoarterial extracorporeal lung assist (ECLA) with low dose systemic heparin in goats. We compared heparin bonded circuits (Carmeda Bioactive Surface, "HB" group, n = 5) with non heparin bonded circuits ("NHB" group, n = 5) in venoarterial ECLA (V-A ECLA) for 7 days. Activated coagulation time (ACT) was maintained at approximately 130 sec by systemic infusion of small doses of heparin in the HB group, and at 200-230 sec in the NHB group. Thrombus formation was assessed by visual examination of the circuit, and possible cerebral embolization of thrombi was observed from behavioral abnormalities of the animals. The mean heparin dose given during ECLA was 20.4 +/- 3.6 U/kg per hr in HB, and 50.9 +/- 14.2 U/kg per hr in NHB, significantly less in HB than NHB (p < 0.01). Blood gas changes across the oxygenator, bypass flow rate, platelet aggregation activity, platelet counts, fibrin monomer (FM) test, and antithrombin-III (AT-III) activity did not differ between the two groups. In HB, thrombi were fewer and no abnormal neurologic symptoms were observed during ECLA. Numerous thrombi were observed in all oxygenators with NHB. One NHB goat developed convulsions and cerebral hemorrhage on the 6th day of ECLA. Nonmicroporous polyolefin hollow fibers can be bonded with heparin. An artificial membrane lung constructed of these fibers showed good anticoagulation by decreased thrombus formation with a small dose of infused heparin.

Quantification of recirculation by thermodilution during venovenous extracorporeal membrane oxygenation

PURPOSE

The aim of this study was to determine whether recirculation could be quantified by a thermodilution technique during venovenous (VV) extracorporeal membrane oxygenation (ECMO) in a rabbit model.

METHODS

Five New Zealand white rabbits, mean weight, 4.5 (range, 3.7 to 5.7) kg, were anesthetized, instrumented, cannulated with a double-lumen catheter, and placed on VV ECMO. Serial injections of ice-cold saline were performed at the arterial arm of the circuit, and the resultant temperature change at various pump flows was measured at the venous arm of the circuit using a thermistor-tipped catheter and a cardiac output computer. Results were compared with the respective 100% recirculation measured with all the circuit flow passing through the bridge.

RESULTS

Using linear regression, recirculation percentage could be calculated as: 19 + 0.1 x pump flow (R2 = 0.81, P < .005). Recirculation correlated positively with pump flow. Variability between results at each flow was less than 10%.

CONCLUSIONS

Recirculation can be quantified during VV ECMO by measuring the change in temperature in the venous arm using a cardiac output computer after injection of a known quantity of ice-cold saline in the arterial side of the circuit. The effect of interventions to reduce recirculation can be assessed conveniently and reliably.

A siliconized hollow fiber membrane oxygenator

Most membrane oxygenators are built with microporous fibers known for plasma leakage in long-term use such as extracorporeal life support or extracorporeal membrane oxygenation. The current study was designed to evaluate the Quadrox oxygenator in which the fibers have been coated with silicone (Jostra). Six calves (mean weight, 62 +/- 4 kg) were connected to cardiopulmonary bypass (CPB) by jugular venous and carotid arterial cannulation, with a mean flow rate of 3 L/min for 6 hours. They were randomly assigned to a standard Quadrox oxygenator (standard group, n = 3) or a siliconized Quadrox oxygenator (silicone group, n = 3). After 7 days, the animals were sacrificed. A standard battery of blood samples was taken before bypass, after mixing for 10 minutes, and after 1, 2, 5, and 6 hours of perfusion. Analysis of variance was used for repeated measurements. Total oxygen transfer and carbon dioxide transfer did not differ between groups (p = 0.5 for comparison). Blood trauma, evaluated by plasma hemoglobin (Hb), did not detect any significant hemolysis in either group. Thrombocyte and white blood cell count profiles in both groups were parallel and without significant differences (p = 0.1 and 0.6, respectively). At the end of testing no clot deposition was found in the oxygenator. At postmortem, there were no signs of peripheral emboli. The results of this study suggest that this silicone coating of hollow fibers allows for good gas transfer, while preserving all the mechanical advantages of a conventional hollow fiber oxygenator.

Cardiovascular complications adversely affect survival during extracorporeal membrane oxygenation

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) has been used in the management of infants with cardiorespiratory failure. ECMO causes a decrease in load-dependent measures of cardiac performance that have not been demonstrated to affect patient outcome, while other cardiovascular complications occur which may affect outcome. The purpose of this study was to describe the cardiovascular complications associated with ECMO, and to determine their relationship to survival.

DESIGN

Data were obtained, retrospectively, from the medical records of 500 consecutive newborns treated with ECMO at our institution since 1984.

RESULTS

Hypertension (mean arterial pressure of >65 mm Hg) was the most common complication, requiring medical intervention in 192 infants. Myocardial stun, the near-total absence of systolic function during ECMO, occurred in 59 infants. Rhythm abnormalities, including noncannulation-related bradycardia, occurred in 43 infants, cardiac arrest, and pericardial effusion in 17 infants, and noninfective thrombosis in 9 infants. Only one infant required ligation of a patent ductus arteriosus during ECMO. Infants with at least one cardiovascular complication had a lower survival rate, compared with those infants without a complication. Survival rates were decreased in infants with myocardial stun, arrhythmia, and cardiac arrest. Hypertension and pericardial effusion were not associated with decreased survival.

CONCLUSION

These findings suggest that some cardiovascular complications during ECMO are more common than previously thought, and cardiovascular complications may adversely impact outcome.

Inhaled nitric oxide for the early treatment of persistent pulmonary hypertension of the term newborn: a randomized, double-masked, placebo-controlled, dose-response, multicenter study. The I-NO/PPHN Study Group

OBJECTIVES

To assess the dose-related effects of inhaled nitric oxide (I-NO) as a specific adjunct to early conventional therapy for term infants with persistent pulmonary hypertension (PPHN), with regard to neonatal outcome, oxygenation, and safety.

METHODS

Randomized, placebo-controlled, double-masked, dose-response, clinical trial at 25 tertiary centers from April 1994 to June 1996. The primary endpoint was the PPHN Major Sequelae Index ([MSI], including the incidence of death, extracorporeal membrane oxygenation (ECMO), neurologic injury, or bronchopulmonary dysplasia [BPD]). Patients required a fraction of inspired oxygen [FIO2] of 1.0, a mean airway pressure >/=10 cm H2O on a conventional ventilator, and echocardiographic evidence of PPHN. Exogenous surfactant, concomitant high-frequency ventilation, and lung hypoplasia were exclusion factors. Control (0 ppm) or nitric oxide (NO) (5, 20, or 80 ppm) treatments were administered until success or failure criteria were met. Due to slowing recruitment, the trial was stopped at N = 155 (320 planned).

RESULTS

The baseline oxygenation index (OI) was 24 +/- 9 at 25 +/- 17 hours old (mean +/- SD). Efficacy results were similar among NO doses. By 30 minutes (no ventilator changes) the PaO2 for only the NO groups increased significantly from 64 +/- 39 to 109 +/- 78 Torr (pooled) and systemic arterial pressure remained unchanged. The baseline adjusted time-weighted OI was also significantly reduced in the NO groups (-5 +/- 8) for the first 24 hours of treatment. The MSI rate was 59% for the control and 50% for the NO doses (P = .36). The ECMO rate was 34% for control and 22% for the NO doses (P = .12). Elevated methemoglobin (>7%) and nitrogen dioxide (NO2) (>3 ppm) were observed only in the 80 ppm NO group, otherwise no adverse events could be attributed to I-NO, including BPD.

CONCLUSION

For term infants with PPHN, early I-NO as the sole adjunct to conventional management produced an acute and sustained improvement in oxygenation for 24 hours without short-term side effects (5 and 20 ppm doses), and the suggestion that ECMO use may be reduced.

An approach to the treatment of severe adult respiratory failure

OBJECTIVES

The purpose of this article is to evaluate outcome in adult patients with severe respiratory failure managed with an approach using (1) limitation of end inspiratory pressure, (2) inverse ratio ventilation, (3) titration of PEEP by SvO2, (4) intermittent prone positioning, (5) limitation of FiO2, (6) diuresis, (7) transfusion, and (8) extracorporeal life support (ECLS) if patients failed to respond.

PATIENTS AND METHODS

This study was designed as a retrospective review in the intensive care unit of a tertiary referral hospital. One-hundred forty-one consecutive patients with hypoxic (n = 135) or hypercarbic (n = 6) respiratory failure referred for consideration of ECLS between 1990 and 1996. Overall, initial PaO2/FiO2 (P/F) ratio was 75+/-5 (median = 66).

RESULTS

Lung recovery occurred in 67% of patients and 62% survived. Forty-one patients improved without ECLS (83% survived); 100 did not and were supported with ECLS (54% survived). Survival was greater in patients cannulated within 12 hours of arrival (59%) compared with those cannulated after 12 hours (40%, P < .05). Multiple logistic regression identified age, duration of mechanical ventilation before transfer, four or more dysfunctional organs, and the requirement for ECLS as independent predictors of mortality.

CONCLUSIONS

An approach that emphasizes lung protection and early implementation of extracorporeal life support is associated with high rates of survival in patients with severe respiratory failure.

Percutaneous access for venovenous extracorporeal life support in neonates

BACKGROUND

Although percutaneous cannulation has been previously described in adult and pediatric patients older than 3 years, its use in neonates for venovenous extracorporeal life support (ECLS) has not been previously described.

METHODS

Twenty neonates of weight 3.4 +/- 0.6 kg (range, 2.3 to 4.9 kg.) with severe respiratory failure (meconium aspiration syndrome, persistent pulmonary hypertension of the newborn, sepsis) were managed with double-lumen venovenous ECLS. Percutaneous access via the right internal jugular (RIJ) vein with a 12F (n = 13) or 15F (n = 7) double-lumen ECLS cannula was obtained via a modified Seldinger technique. RIJ access was specifically obtained 2 to 3 cm above the clavicle with a 21-gauge needle and a 0.018-in guide wire followed by a technique that allowed insertion of the larger cannula guide wire. Decannulation simply involved removal of the cannula with hemostasis obtained by direct pressure.

RESULTS

Percutaneous cannulation was performed without difficulty in 11 infants. Conversion to an open technique for cannula placement was required in four patients early in our experience because percutaneous access to the RIJ with the 0.018-inch guide wire could not be achieved, and in one neonate because the 15F cannula could not be advanced into the RIJ and resulted in laceration of the vein. Inability to achieve RIJ access also led to use of an "exposure-assisted" percutaneous procedure in four patients later in our experience. Complications included a pneumothorax identified on chest radiograph 18 hours after cannulation in one infant and partial thrombotic occlusion of the cannula requiring a change over a guide wire in another. There were no problems associated with decannulation.

CONCLUSIONS

This is the first description of percutaneous cannulation in neonates for venovenous ECLS. In the authors' early experience, percutaneous access using a 12F double lumen venovenous cannula may be efficiently performed especially in patients >3.0 kg in weight and has the potential for simplifying and reducing the cost of the ECLS technique.

Extracorporeal life support for 100 adult patients with severe respiratory failure

OBJECTIVE

The authors retrospectively reviewed their experience with extracorporeal life support (ECLS) in 100 adult patients with severe respiratory failure (ARF) to define techniques, characterize its efficacy and utilization, and determine predictors of outcome.

SUMMARY BACKGROUND DATA

Extracorporeal life support maintains gas exchange during ARF, providing diseased lungs an optimal environment in which to heal. Extracorporeal life support has been successful in the treatment of respiratory failure in infants and children. In 1990, the authors instituted a standardized protocol for treatment of severe ARF in adults, which included ECLS when less invasive methods failed.

METHODS

From January 1990 to July 1996, the authors used ECLS for 100 adults with severe acute hypoxemic respiratory failure (n = 94): paO2/FiO2 ratio of 55.7+/-15.9, transpulmonary shunt (Qs/Qt) of 52+/-22%, or acute hypercarbic respiratory failure (n = 6): paCO2 84.0+/-31.5 mmHg, despite and after maximal conventional ventilation. The technique included venovenous percutaneous access, lung "rest," transport on ECLS, minimal anticoagulation, hemofiltration, and optimal systemic oxygen delivery.

RESULTS

Overall hospital survival was 54%. The duration of ECLS was 271.9+/-248.6 hours. Primary diagnoses included pneumonia (49 cases, 53% survived), adult respiratory distress syndrome (45 cases, 51 % survived), and airway support (6 cases, 83% survived). Multivariate logistic regression modeling identified the following pre-ECLS variables significant independent predictors of outcome: 1) pre-ECLS days of mechanical ventilation (p = 0.0003), 2) pre-ECLS paO2/FiO2 ratio (p = 0.002), and 3) age (years) (p = 0.005). Modeling of variables during ECLS showed that no mechanical complications were independent predictors of outcome, and the only patient-related complications associated with outcome were the presence of renal failure (p < 0.0001) and significant surgical site bleeding (p = 0.0005).

CONCLUSIONS

Extracorporeal life support provides life support for ARF in adults, allowing time for injured lungs to recover. In 100 patients selected for high mortality risk despite and after optimal conventional treatment, 54% survived. Extracorporeal life support is extraordinary but reasonable treatment in severe adult respiratory failure. Predictors of survival exist that may be useful for patient prognostication and design of future prospective studies.

Carotid artery reconstruction in neonates receiving extracorporeal membrane oxygenation: a 4-year follow-up study. Western Canadian ECMO Follow-Up Group

Although venoarterial extracorporeal membrane oxygenation (ECMO) is an accepted form of cardiopulmonary support for critically ill neonates, carotid artery reconstruction (CAR) after decannulation remains controversial. Long-term follow-up information regarding the natural progression of the anastomosis is unavailable. From January 1990 through December 1990, 13 venoarterial neonatal ECMO survivors had CAR performed and were enrolled into this prospective study based on sonographic follow-up of CAR. A total of 34 carotid artery sonographic studies were performed (13 within 1 week after reconstruction, 8 at 6 to 9 months, and 13 at 4 years of age). A high patency rate during the neonatal period was observed (12 of 13, 92%). Among 12 children with normal neonatal sonographic studies, 5 had completely normal studies during 4 years of follow-up. Narrowing at the anastomotic site (defined as structural narrowing with velocity ratio of peak systolic velocity at the anastomosis to peak systolic velocity proximal to the anastomosis > 1.0 but < or =2.0) by 4 years of age developed in 7 children. Two of these 7 children had hemodynamically significant stenotic anastomosis (defined as structural narrowing with velocity ratio >2.0) by 4 years of age. One neonate had a narrowed anastomosis that resolved completely by the age of 4 years. The incidence of normal studies decreased from 92% to 75% to 46% during the neonatal period, at 6 to 9 months, and at 4 years follow-up, respectively (Chi-square test for trend, P < .01). Long-term follow-up information on the natural progression of carotid reanastomosis is required.

The effects of venous occlusion on cerebral blood flow characteristics during ECMO

Extracorporeal membrane oxygenation (ECMO) in the newborn usually requires occlusion of a jugular vein, and frequently a carotid artery. The acute effects of jugular vein occlusion on cerebral blood flow characteristics have received little investigation. Six newborns (age range, 0 to 5 days; weight, 2.4 to 3.1 kg) were treated with venoarterial ECMO, with additional placement of a cephalic venous catheter, for meconium aspiration (4) or persistent fetal circulation (2). Doppler duplex ultrasound evaluation of blood flow velocity and resistive index (RI) in the right (RMCA) and left (LMCA) middle cerebral arteries was performed just before ECMO, immediately after ECMO onset, and at 8,24, and 48 hours of ECMO. Arterial Po2 was maintained at 80 to 120 mm Hg. Pco2 at 35 to 45 mm Hg. and mean arterial pressure at 50 to 60 mm Hg. Flow velocity was measured with the cephalic venous catheter both open and closed. Closure of the cephalic venous cannula resulted in an abrupt, significant reduction in RMCA flow velocity and a significant increase in RI at the onset of ECMO and at 8 hours of ECMO. Opening the cannula restored the velocity and RI to normal. LMCA velocity and RI did not change with closure of the cephalic venous cannula. All infants survived ECMO, and five of the six are normal neurologically at 1 year of age. These data show that right carotid ligation alone did not change cerebral arterial blood flow velocity, but the addition of venous occlusion significantly decreased RMCA flow velocity, which was alleviated by cephalic venous drainage. After 24 hours of ECMO, this effect disappeared. This suggests that cephalic venous drainage may help prevent the neurological complications of ECMO by maintaining normal cerebral blood flow.

Modern treatment modalities for neonatal and pediatric respiratory failure

BACKGROUND

Respiratory failure secondary to a variety of causes remains a significant cause of morbidity and mortality in the pediatric population. Newer therapies are appearing frequently in an attempt to decrease the number of deaths from this disease state. We briefly review the current literature on some of the newer modalities including: high-frequency ventilation, surfactant, liquid ventilation, and nitric oxide. We then present our experience from the past 11 years in the most invasive, yet successful, therapy for acute respiratory failure-extracorporeal membrane oxygenation (ECMO).

METHODS

Retrospective review of all patients treated with ECMO from September 1983 to December 1994 was undertaken. Data were collected from bedside ECMO flow sheets and the standardized data entry forms submitted to the Extracorporeal Life Support Organization. All statistical analyses were performed using a standard statistical software program.

RESULTS

During the study period, 194 neonates and 47 pediatric patients were treated with ECMO. The survival rate in the neonatal population is 82% and in the pediatric population it is 40%. The neonatal patients required an average of 153 hours of support while the pediatric patients required 220 hours (P = 0.008).

CONCLUSIONS

While the newer treatment modalities discussed may have an important role in treating neonatal and pediatric respiratory failure in the near future, ECMO remains a cornerstone of the modern treatment modalities. Although somewhat invasive, ECMO is effective therapy with increasing survival rates each year.

Cannulation of neonates for venovenous extracorporeal life support

Venovenous access via a double-lumen cannula in the right internal jugular vein is the extracorporeal life support mode of choice for neonates with respiratory failure. We report a simplified method of cannulation. The advantages of this "semi-Seldinger" method include the ability to cannulate without ligating the internal jugular vein, and to adjust the position of the cannula and decannulate without re-exploring the wound.

Current status of extracorporeal membrane oxygenation for severe respiratory failure

Extracorporeal membrane oxygenation (ECMO) for respiratory failure was reviewed. ECMO progressed from laboratory research to initial clinical trials in 1972. Following a decade of clinical research, ECMO is now standard treatment for neonatal respiratory failure refractory to conventional pulmonary support techniques worldwide. The application of neonatal ECMO has been extended with improved outcome to premature and low birth weight infants as well as older children and adults. As of July 1994, 9,258 neonates, 754 pediatric, and 130 adult patients with respiratory failure treated with ECMO were entered in the registry of the Extracorporeal Life Support Organization (ELSO). Overall survival rates were 81% in neonates, 49% in pediatric, and 38% in adult patients. Recently the adult and pediatric populations treated with ECMO have increased rapidly, and the outcome has improved significantly.

Nucleated erythrocyte count in newborn infants with left-sided congenital diaphragmatic hernia: relationship with the need for extracorporeal membrane oxygenation and survival

Inadequate cardiac output in fetuses with left-sided congenital diaphragmatic hernia may cause chronic hypoxia and increased erythropoiesis. Postnatal nucleated erythrocyte counts were measured in 28 newborn infants with left-sided congenital diaphragmatic hernia who were eligible for extracorporeal membrane oxygenation (ECMO). Nucleated erythrocyte counts were lowest in infants who survived without ECMO, intermediate in survivors requiring ECMO, and highest in infants who died despite ECMO.