Venovenous extracorporeal membrane oxygenation in neonates with respiratory failure

Device updates in pediatric and neonatal ECMO

Since the early use of extracorporeal life support (ECLS), new innovations and technological advancements have augmented the ability to use this technology in children and neonates. Cannulae have been re-designed to maintain structure and allow for single cannula venovenous (VV) ECLS in smaller patients. Circuit technology, including pumps and tubing, has evolved to permit smaller priming volumes and lower flow rates with fewer thrombotic or hemolytic complications. New oxygenator developments also improve efficiency of gas exchange. This paper serves as an overview of recent device developments in ECLS delivery to pediatric and neonatal patients.

Cannulation and decannulation techniques for neonatal ECMO

In neonates with cardiac and/or respiratory failure, extracorporeal membrane oxygenation (ECMO) continues to be an important method of respiratory and/or cardiovascular support where conventional treatments are failing. ECMO cannulation involves a complex decision-making process to choose the proper ECMO modality and cannulation strategy to match each patient's needs, unique anatomy, and potential complication profile. Initially, all ECMO support involved cannulating both the carotid artery and the internal jugular vein (IJV), known as veno-arterial (VA-ECMO) for cardiac and/or respiratory support. Rarely was cannulation through the chest used. The development of dual-lumen cannulae in the early to mid 1990s addressed the concerns about carotid artery ligation and its impact on neurological outcomes, and allowed single vascular access for veno-venous respiratory support (VV-ECMO). We present a review of cannulation and decannulation techniques for both VA and VV-ECMO in neonates.

Pediatric extracorporeal membrane oxygenation: Our experience with single-vessel cannulation

Background

In this study, we present our experience with bicaval, dual-lumen, venovenous extracorporeal membrane oxygenation in pediatric patients with severe respiratory failure.

Methods

Between September 2015 and May 2019, a total of nine pediatric patients (7 males, 2 females; median age 3.1 years; range, 0.3 to 7.4 years) hospitalized in the pediatric intensive care unit due to severe respiratory failure who were cannulated using a bicaval, dual-lumen, venovenous catheter were retrospectively analyzed. Patient demographics, cannulation details, complication of catheter use, and outcomes were recorded.

Results

The median duration of extracorporeal membrane oxygenation support was nine (range, 2 to 32) days. One patient required conversion to venoarterial extracorporeal membrane oxygenation and one patient required conversion to conventional double-cannulated venovenous extracorporeal membrane oxygenation. Of the patients, 33% suffered from bleeding complications. There were no cannula- or circuit-related complications. Adequate oxygenation and flow were obtained in all patients, except one. No mortalities were directly associated with the cannulation strategy used.

Conclusion

The bicaval, dual-lumen cannula can be safely used in pediatric patients with minimal complication rates and is our preferred method for venovenous extracorporeal membrane oxygenation support.

Outcomes and associated ethical considerations of long-run pediatric ECMO at a single center institution

PURPOSE

Survival of neonatal and pediatric patients undergoing extracorporeal membrane oxygenation (ECMO) ≥ 21 days has not been well described. We hypothesized that patients would have poor survival and increased long-term complications.

METHODS

Retrospective, single center, review and case analysis. Tertiary-care university children's hospital including neonatal, pediatric and cardiac intensive care units. After institutional review board approval, the charts of all patients < 18 years of age undergoing ECMO for ≥ 21 continuous days were performed, and they were compared to comparative patients undergoing shorter runs. Overall survival, incidence of complications, and post-discharge recovery were recorded.

RESULTS

Overall survival was 36% in patients undergoing ≥ 21 days of ECMO (N = 14). 5/8 patients with cardiopulmonary failure from acquired etiologies survived versus 0/6 patients with congenital anomalies. 1/5 survivors achieved complete recovery with no neurologic deficits. The remaining survivors suffer from multiple medical and neurodevelopmental morbidities.

CONCLUSION

ECMO support for ≥ 21 days is associated with poor survival, particularly in neonates with congenital anomalies. Long-term outcomes for survivors ought to be carefully weighed and discussed with parents given the high incidence of neurologic morbidities in this population.

Short- and long-term mechanical cardiac assistance

With the increase in high risk patients undergoing cardiac surgery and the substantial mortality among patients waiting for cardiac transplantation, the need for mechanical circulatory support is growing. Several devices are currently available, ranging from the intra-aortic balloon pump to fully implantable ventricular assist devices. Each system has its own features, and proper patient selection as well as the timing of implantation is sometimes difficult. Algorithms for stepwise management in subgroups of patients remain controversial and the concepts of weaning patients after myocardial recovery during mechanical circulatory support need further evaluation for their long-term effects. Future identification of valuable prognostic and risk factors may help in decision-making and allow for improved survival of these often very ill patients. In this report we review the concepts of mechanical circulatory support at our institution with emphasis on a detailed overview of technical features of extracorporeal life support.

Prognosis and Outcome of Neonates Treated Either with Veno-Arterial (VA) or Veno-Venous (VV) ECMO

A comparison was done between neonates requiring veno-arterial (VA) ECMO (too small jugular vein, inability to insert a 12 Fr double lumen catheter or cardio-circulatory instability) and neonates treated with veno-venous (VV) ECMO in the same period of time. From 1991-1995 ECMO was done in 48 neonates after failure of maximum conventional treatments, NO-inhalation and HFOV. 30/48 babies were treated with VV-ECMO, with a switch to VA-ECMO later on in 3 of them. In 18 infants VA-ECMO was installed primarily. Differences between the VA- and VV-ECMO group were: the 01 was higher in the VV-treated babies (62±20 vs. 48±13, p < 0.03), as were birth weight (3385±570 vs. 2963±653 g, p< 0.04), gestational age (39.7 ± 1.6 vs. 37.9 ± 2.7 weeks, p< 0.01) and MAP (18.7 ± 2.2 vs. 17.1 ± 2.4 cm H2O, p< 0.05). Severe ICH's occurred more frequently in the VA-treated babies (29 vs. 7%, p< 0.05), the rate of other complications was equal. The mortality rates were 43% (VA) and 15% (VV), p< 0.05. About one third of neonatal ECMO candidates will be treated with VA-ECMO, even if the VV-ECMO technique is available. Need for VA-ECMO implies - due to a higher number of preterm babies and a greater severity of illness before ECMO - a higher incidence of ICH's and a higher mortality rate.

Neonatal Extracorporeal Membrane Oxygenation: A Review

The history of extracorporeal membrane oxygenation (ECMO) therapy is summarized. The adult and pediatric experiences are described, but emphasis is placed on the development of neonatal ECMO, now an accepted therapy for newborns with severe respiratory failure. The technical aspects of neonatal ECMO are outlined, as are the clinical criteria for its use. Experience at Children's Hospital National Medical Center, Washington, DC, is reported. Promising new technological developments, and their implications for future applications of neonatal ECMO, are presented.

Bicaval dual-lumen cannula for venovenous extracorporeal membrane oxygenation: Avalon© cannula in childhood disease

Severe acute refractory respiratory failure is considered a life-threatening situation, with a high mortality of 40 to 60%. When conservative oxygenation methods fail, a lifesaving measure is the introduction of extracorporeal membrane oxygenation (ECMO). Venovenous ECMO (VV-ECMO) is a preferred modality of support for patients with refractory acute respiratory failure. Specifically, bicaval VV-ECMO is a well-recognized and validated therapy, where single or double periphery venous access is used for the insertion of two differently sized cannulas in order to achieve adequate blood oxygenation. Compared to venoarterial ECMO, in VV-ECMO, the rate of complications, such as thrombosis, bleeding, infection and ischemic events, is lower. On the other hand, the size and insertion location is an obstacle to patient mobilization. This is a considerable problem for patients where the time interval for lung recovery and the bridge to the transplantation is prolonged. To address this issue, a dual-lumen, single venovenous cannula was introduced. Here, by insertion of one single catheter in one target vessel, in a majority of cases in the right internal jugular vein, satisfactory oxygenation of the patient is achieved. In this form, the instituted VV-ECMO enables patient mobility, better physical rehabilitation and facilitates pulmonary extubation and toilet.

However, relatively early, after the first short-term reports were published, a relatively high complication rate became evident. In the recent literature, the complication rate using actual commercially available double-lumen venovenous cannula ranges between 5 and 30%. These cases were mostly conjoined to the implantation phase or the early postoperative phase and vary between right heart perforation to migration of the cannula.

This review focuses on complications allied to commercially available dual-lumen, single, venovenous cannula implantation, pointing out the critical segments of the implantation process and analyzing the structure of the device.

Comparison of wire-reinforced and non-wire-reinforced dual-lumen catheters for venovenous ECMO in neonates and infants

Improved dual-lumen catheter design has resulted in greater efficiency of gas exchange during extracorporeal life support. However, standard venovenous (S-VV) catheters are prone to structural deformation that reduces flow capacity. Wire-reinforced dual-lumen catheters have recently been introduced to reduce the risk of structural deformation. A retrospective review was performed on 25 neonates and infants who received venovenous extracorporeal life support (ECLS) to evaluate the occurrence and nature of catheter-related complications and events related to interrupted ECLS. Comparisons were made between patients supported with wire-reinforced and non-wire-reinforced dual-lumen catheters. No significant difference in number of catheter-related complications or flow-interruption events was observed. The use of wire-reinforced catheters appeared to increase the risk of cardiac perforation whereas non-wire-reinforced catheters appeared to be more prone to early failure. Once support was established, interruptions of extracorporeal flow occurred with the same frequency during the initial 72 hours, regardless of the type of catheter used. Further improvements in dual-lumen VV catheter design may reduce the risk of failure and injury and improve efficiency of extracorporeal gas exchange.

Initial experience with single-vessel cannulation for venovenous extracorporeal membrane oxygenation in pediatric respiratory failure

OBJECTIVES

Venovenous extracorporeal membrane oxygenation has been used to provide cardiopulmonary support in critically ill infants and children. Recently, dual-lumen venovenous extracorporeal membrane oxygenation has gained popularity in the pediatric population. Herein, we report our institutional experience using a bicaval dual-lumen catheter for pediatric venovenous extracorporeal membrane oxygenation support, which has been our unified approach for venovenous extracorporeal membrane oxygenation since 2009.

DESIGN

This study is a retrospective review.

SETTING

The setting is a tertiary children's hospital in a major metropolitan area.

PATIENTS

Between 2009 and 2011, 11 patients were cannulated using a dual-lumen bicaval venous catheter. Patient demographics, cannulation details, circuit complications, complications of catheter use, and patient outcomes were collected from a retrospective chart review.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eleven of the patients were cannulated for venovenous extracorporeal membrane oxygenation using the dual-lumen bicaval cannula. The median age at the time of venovenous cannulation was 1.9 years (range, 0.14-17.1), and the median weight was 10.2 kg (range, 3-84). Three patients (27%) required conversion to venoarterial extracorporeal membrane oxygenation. The median duration of extracorporeal membrane oxygenation support was 10 days (2-38 days). Fifty-five percent of patients suffered from a bleeding complication (disseminated intravascular coagulation, pulmonary hemorrhage, or intraventricular hemorrhage), and 45% had a circuit complication. Adequate flow rates were achieved in all patients. The overall hospital mortality in the series was 55%. There were no cannula-related complications.

CONCLUSIONS

This review presents the first single-institution experience with the dual-lumen Avalon cannula in pediatric patients. Preliminary results indicate that the catheter can be safely placed and has an acceptable complication profile; however, continued study within larger trials is necessary to fully ascertain the clinical profile of this catheter.

The pulmonary circulation in neonatal respiratory failure

The pulmonary circulation rapidly adapts at birth to establish lungs as the site of gas exchange. Abnormal transition at birth and/or parenchymal lung disease can result in neonatal hypoxemic respiratory failure. This article reviews the functional changes in pulmonary hemodynamics and structural changes in pulmonary vasculature secondary to (1) normal and abnormal transition at birth, and (2) diseases associated with neonatal hypoxemic respiratory failure. Various management strategies to correct respiratory failure are also discussed.

The endocrinological responses of veno-venous extracorporeal membrane oxygenation on hypoxic fetal lambs

OBJECTIVE

The purpose of this study was to observe endocrinological responses of veno-arterial and veno-venous extracorporeal membrane oxygenation (V-A and V-V ECMO) to support fetal oxygenation in utero.

METHODS

An ECMO system with a centrifugal pump was applied to six chronically instrumented fetal lambs, at 126-134 days of gestation. Blood was obtained through a double-lumen catheter inserted into the right atrium. After oxygenation, the blood was returned through a single-lumen catheter into either the carotid artery (veno-arterial; V-A ECMO) or the right atrium (V-V ECMO). After fetal hypoxia had been experimentally produced, V-A ECMO or V-V ECMO was instituted to maintain fetal oxygenation. We compared fetal blood gases and concentrations of atrial natriuretic peptide (ANP), epinephrine and norepinephrine with both routes of ECMO.

RESULTS

Fetal carotid artery pH did not change during hypoxemia, but decreased after instituting V-A ECMO and V-V ECMO. After instituting V-A ECMO or V-V ECMO for 30 min, oxygen partial pressure (pO2) in the fetal cranial carotid artery recovered from the hypoxic level. The ANP concentration in V-V ECMO was significantly lower than that in V-A ECMO. Fetal serum epinephrine and norepinephrine concentrations significantly increased in association with hypoxic stimulation. There was a further increase in fetal serum epinephrine concentration after instituting V-A ECMO. No significant difference in concentration was found after instituting V-V ECMO from that of after the institution of V-A ECMO.

CONCLUSIONS

This study suggested that V-V ECMO may possibly be less invasive than V-A ECMO for fetal heart, because ANP, a cardiac distress index, was lower in V-V ECMO than in V-A ECMO.

Challenges to cannulation for extracorporeal support in neonates with right-sided congenital diaphragmatic hernia

Right-sided diaphragmatic defects represent less than 20% of all congenital diaphragmatic hernias (CDH). Recent data suggest that right CDH (R-CDH) may carry a disproportionately high morbidity as well as increased rates of extracorporeal support when compared with left CDH. Treatment of infants with R-CDH may be further complicated by anatomical distortion unique to right-sided defects. We report 2 cases of azygous vein cannulation in neonates with large isolated R-CDH. Both infants had postnatal deteriorations within 48 hours, met our criteria for extracorporeal membrane oxygenation (ECMO), and underwent venoarterial cannulations through the right neck. In each case, the venous cannula passed directly into the azygous vein and failed to provide adequate ECMO support. Echocardiography confirmed both cases of azygous cannulation. In one child, the right atrium was successfully cannulated after 90 minutes of extensive cannula manipulation. This child survived a 5-day ECMO course and is alive at 22-month follow-up. In the second child, despite prolonged efforts at cannula repositioning, cannulation of the right atrium was not achieved. We did not offer central cannulation because of a rapidly deteriorating clinical course, with expiration in several hours. At autopsy, a dilated azygous vein was evident as a result of inferior vena cava compression by a malpositioned liver. The possibility of azygous vein cannulation may be increased in neonates with R-CDH and has not been previously reported. When evaluating infants with R-CDH for ECMO, clinicians must recognize the possibility of azygous cannulation and its potentially lethal consequences, and should anticipate alternative venous cannulation.

Primary use of the venovenous approach for extracorporeal membrane oxygenation in pediatric acute respiratory failure

OBJECTIVES

To describe a single center's experience with the primary use of venovenous cannulation for supporting pediatric acute respiratory failure patients with extracorporeal membrane oxygenation (ECMO).

DESIGN

Retrospective chart review of all patients receiving extracorporeal life support at a single institution.

SETTING

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

PATIENTS

Eighty-two patients between the ages of 2 wks and 18 yrs with severe acute respiratory failure.

INTERVENTIONS

ECMO for acute respiratory failure.

MEASUREMENTS AND MAIN RESULTS

From January 1991 until April 2002, 82 pediatric patients with acute respiratory failure were cannulated for ECMO support. Median duration of ventilation before ECMO was 5 days (range, 1-17 days). Sixty-eight of these patients (82%) initially were placed on venovenous ECMO. Fourteen patients were initiated and remained on venoarterial support, including six in whom venovenous cannulae could not be placed. One patient was converted from venovenous to venoarterial support due to inadequate oxygenation. Venoarterial patients had significantly greater alveolar-arterial oxygen gradients and lower PaO(2)/FIO(2) ratios than venovenous patients (p <.03). Fifty-five of 81 venovenous patients received additional drainage cannulae (46 of 55 with an internal jugular cephalad catheter). Thirty-five percent of venovenous patients and 36% of venoarterial patients required at least one vasopressor infusion at time of cannulation (p = nonsignificant); vasopressor dependence decreased over the course of ECMO in both groups. Median duration on venovenous ECMO for acute hypoxemic respiratory failure was 218 hrs (range, 24-921). Venovenous ECMO survivors remained cannulated for significantly shorter time than nonsurvivors did (median, 212 vs. 350 hrs; p =.04). Sixty-three of 82 ECMO (77%) patients survived to discharge-56 of 68 venovenous ECMO (81%) and nine of 14 venoarterial ECMO (64%).

CONCLUSIONS

Venovenous ECMO can effectively provide adequate oxygenation for pediatric patients with severe acute respiratory failure receiving ECMO support. Additional cannulae placed at the initiation of venovenous ECMO could be beneficial in achieving flow rates necessary for adequate oxygenation and lung rest.

The Edmonton experience with venovenous extracorporeal membrane oxygenation

BACKGROUND/PURPOSE

Despite the proven effectiveness of venovenous extracorporeal membrane oxygenation (VV ECMO) in the treatment of neonates with severe respiratory failure, this technique is not widely used. The purpose of this study was to assess the authors' policy of preferred use of VV ECMO with a cephalad catheter and to compare the results with those of the Extracorporeal Life Support Organization (ELSO) Registry.

METHODS

Charts of neonatal ECMO candidates were reviewed retrospectively. Data were collected for gestational age, birth weight, and diagnosis. Severity of illness was assessed by oxygenation index, lactate levels, and inotropic requirements before cannulation. Patients were divided into three groups: venovenous (VV), venoarterial (VA), and VV to VA ECMO. A cephalad catheter was inserted in the distal part of the jugular vein.

RESULTS

Sixty-five neonates were supported with ECMO. Cannulation with a double lumen venovenous (VVDL) catheter was attempted in 63 neonates and successfully accomplished in 57. A survival rate of 86% was observed in neonates initially placed on VV ECMO. Five neonates initially placed on VV ECMO underwent conversion to VA ECMO.

CONCLUSIONS

This study showed that the authors' preferred policy of VV ECMO did not result in an increase in mortality rate based on a comparison with ELSO data. VV ECMO with a cephalad catheter provides adequate support for unstable neonates with respiratory failure.

Venovenous extracorporeal membrane oxygenation in newborn infants using the umbilical vein as a reinfusion route

PURPOSE

The authors report on four neonates treated with venovenous (VV) extracorporeal membrane oxygenation (ECMO) using the umbilical vein as a reinfusion route.

METHODS

From 1994 to 1997, 26 instances VV-ECMO in neonates have been carried out at our neonatal center for the treatment of severe respiratory and cardiac failure. Among them, 22 patients could be treated with VV-ECMO mainly using 15F double-lumen catheter (DLC), adding the cephalic drainage using another catheter. In the remaining four cases, however, attempts to insert the DLC into the right internal jugular vein failed because the vein was too small or technical problems. For such instances, two catheters were cannulated into the right atrium and the cephalic portion of the right internal jugular vein, respectively. These two venous catheters were connected to the drainage route of ECMO circuit with a "Y" connector. Then, the umbilical vein was cannulated with 10F or 8F catheter, which was connected to the reinfusion route of ECMO to return the oxygenated blood to the infant.

RESULTS

The median age at which ECMO was initiated was 18 hours, and the median ECMO course was 72 hours. The liver function tests were slightly and transiently worsened in two patients during VV perfusion, (in one patient serum glutamic-oxaloacetic transaminase [SGOT] elevated to 76 IU/L and serum glutamic-pyruvic transaminase [SGPT] to 49 IU/L, and in another patient SGOT elevated to 56 IU/L and SGPT remained in normal range). Preumbilical cannula pressures were measured in two patients. In a patient who used 10F umbilical cannula, the preumbilical maximum pressure was 43 mm Hg at 250 mL/min of ECMO flow. In another with an 8F catheter, it was 72 mm Hg at 180 mL/min of ECMO flow. All of the patients survived without any neurological complications.

CONCLUSIONS

If the right internal jugular vein would not accommodate the DLC, VV-ECMO using the umbilical vein as a infusion route could be selected.

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.

A comparison of venovenous and venoarterial extracorporeal membrane oxygenation in the treatment of neonatal respiratory failure

OBJECTIVE

To compare the efficacy of venovenous to venoarterial bypass in an unselected cohort of infants with refractory cardiorespiratory failure.

DESIGN

Retrospective cohort analysis.

SETTING

Two tertiary hospitals capable of providing extracorporeal life support for neonates with acute respiratory failure.

PATIENTS

All San Diego Regional Extracorporeal Membrane Oxygenation (ECMO) Program patients treated after the adoption of a policy which eliminated traditional restrictions to venovenous support.

INTERVENTIONS

Venoarterial or venovenous extracorporeal life support.

MEASUREMENTS AND MAIN RESULTS

Fifty-four infants were treated with venovenous bypass; 30 were treated with venoarterial bypass due to unsuccessful placement of the double lumen venovenous catheter or inability to exclude congenital heart disease before cannulation. No patient required conversion from venovenous to venoarterial ECMO. There were no differences in birth weight, gestational age, diagnosis, or pre-ECMO condition in the two groups. Patients who met ECMO criteria early were more likely to be successfully cannulated with a double-lumen venovenous catheter. Severe hemodynamic compromise was present before cannulation in a comparable percentage of venovenous and venoarterial patients. During venovenous bypass, mean Pao2 values were lower but remained in the normoxic range; Paco2 values, ventilatory setting, intravascular volume requirements, inotropic support, and mean duration of ECMO support were not different. The frequency rate of patient and mechanical complications were also comparable, except that the frequency of intravascular thrombosis was significantly lower in patients receiving venovenous ECMO. Survival, the frequency rate of chronic lung disease, and neurodevelopmental outcome were similar in the two groups.

CONCLUSIONS

We conclude that venovenous ECMO using a double-lumen venovenous catheter can provide results comparable with venoarterial bypass without the need for carotid artery ligation in an unselected population of neonatal ECMO candidates. In our experience, reported contraindications to venovenous ECMO did not prove to be valid.

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

OBJECTIVE

The authors reviewed their experience with extracorporeal life support (ECLS) in neonatal respiratory failure; they define changes in patient population, technique, and outcomes.

SUMMARY BACKGROUND DATA

Extracorporeal life support has progressed from laboratory research to initial clinical trials in 1972. Following a decade of clinical research, ECLS is now standard treatment for neonatal respiratory failure refractory to conventional pulmonary support techniques. Our group has the longest and largest experience with this technique.

METHODS

Between 1973 and 1993, 460 neonates with severe respiratory failure were treated using ECLS. The records of all patients were reviewed.

RESULTS

Overall survival was 87%. Primary diagnoses were meconium aspiration syndrome (MAS; 169 cases [96% survival]), respiratory distress syndrome/hyaline membrane disease (91 cases [88% survival]), persistent pulmonary hypertension of the newborn (37 cases [92%]), pneumonia/sepsis (75 cases [84% survival]), congenital diaphragmatic hernia (CDH; 67 cases [67% survival]), and other diagnoses (21 cases [71% survival]). Common mechanical complications included clots in the circuit (136; 85% survival); air in the circuit (67; 82% survival); cannula problems (65; 83% survival) and oxygenator failure (34; 65% survival). Patient-related complications included intracranial infarct or bleed (54 cases; 61% survival), major bleeding (48 cases; 81% survival), seizures (88 cases; 76% survival), metabolic abnormalities (158 cases; 71% survival) and infection (21 cases; 48% survival). Since 1989, treatment groups have been expanded to include premature infants (13 cases; 62% survival), infants with grade I intracranial hemorrhage (28 cases; 54% survival) and "non-honeymoon" CDH patients (15 cases; 27% survival). Since 1990, single-catheter venovenous access has been used in 131 patients (97% survival) and currently is the preferred mode of access. Follow-up ranges from 1 to 19 years; 80% of patients are growing and developing normally.

CONCLUSIONS

Extracorporeal life support has become standard treatment for severe neonatal respiratory failure in our center (460 cases; 87% survival), and worldwide (8913 cases; 81% survival). The availability of ECLS makes the evaluation of other innovative methods of treatment, such as late elective repair of diaphragmatic hernia and new pulmonary vasodilators, possible. The application of ECLS is now being extended to premature and low-birth weight infants as well as older children and adults.

Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation has now evolved into standard therapy for patients unresponsive to conventional ventilatory and pharmacological support. This article presents a clinical review of extracorporeal life support and its application to neonatal and pediatric patients as well as children requiring circulatory support after open heart surgery.

Effects of venovenous extracorporeal membrane oxygenation on cardiac performance as determined by echocardiographic measurements

We evaluated the effects of venovenous extracorporeal membrane oxygenation (ECMO) on cardiac performance by echocardiographic measurements in 15 infants. Heart rate and blood pressure were also recorded. Echocardiographic measurements included aortic and pulmonary peak blood flow velocities, pulmonary time to peak velocity, left ventricular shortening fraction, velocity of circumferential fiber shortening corrected for heart rate, and peak systolic wall stress before, during, and after venovenous ECMO. Pre-ECMO echocardiograms showed borderline or normal indexes of cardiac function. After initiation of venovenous ECMO, all infants had normalization and no infant had deterioration of cardiac performance. The inotropic agents dopamine and dobutamine were decreased from average doses of 12 and 3.6 micrograms/kg per minute, respectively, to 3.7 and 1.3 micrograms/kg per minute, respectively, within 8.8 hours of the institution of venovenous ECMO. During this time the mean arterial pressure remained stable, and the heart rate decreased (169 +/- 21 vs 136 +/- 15 beats/min; p < 0.001). During the course of ECMO there were no changes in left ventricular shortening fraction, velocity of circumferential fiber shortening corrected for heart rate, or aortic peak blood flow velocities. Pulmonary artery peak blood flow velocity (69 +/- 22 vs 92 +/- 28 cm/sec; p = 0.04) and pulmonary time to peak velocity improved (47 +/- 11 vs 65 +/- 16 msec; p = 0.026). We conclude that venovenous ECMO does not have deleterious effects on cardiac performance.

Multicenter comparison of conventional venoarterial access versus venovenous double-lumen catheter access in newborn infants undergoing extracorporeal membrane oxygenation

A multicenter trial was designed to compare standard venoarterial (VA) access versus single-catheter, venovenous access using the double-lumen catheter (VV-DLC) for newborns with respiratory failure undergoing extracorporeal membrane oxygenation (ECMO). Twenty-seven ECMO centers participated, each submitting data from the center's most recent VA cases, and data from VV-DLC cases completed upon entering the study. Data from 135 VA ECMO cases and 108 VV-DLC cases were submitted. All diagnoses resulting in neonatal respiratory failure were submitted, including patients with congenital diaphragmatic hernia (24 patients VA bypass, 11 patients VV-DLC bypass). Overall survival in patients undergoing VA bypass was 87%, while survival in patients undergoing VV-DLC bypass was 95%. Eleven patients required conversion from VV-DLC bypass to VA bypass because of insufficient support--10 of these patients survived (91% survival). Average bypass time for newborns undergoing VA bypass was 132 +/- 7.4 hours versus 100 +/- 5.1 hours for those undergoing VV-DLC bypass. Neurologic complications were more common in the VA bypass patients, although the VV patients were more stable. Hemorrhagic, cardiopulmonary, and mechanical complications, other than kinking of the DLC, occurred with approximately equal frequency in each group. In conclusion, in newborns with adequate cardiac function, venovenous ECMO using the DLC can provide the same level of support as conventional VA ECMO, without ligation of the carotid artery.

Efficacy of venovenous extracorporeal membrane oxygenation for neonates with respiratory and circulatory compromise

We report a 12-month experience at Egleston Children's Hospital in Atlanta, Ga., with a protocol under which venovenous extracorporeal membrane oxygenation (ECMO) was used instead of venoarterial ECMO. Fifty-five newborn infants were referred for ECMO, four of whom had disqualifying conditions (all four died). Thirty-one infants were supported without recourse to ECMO, one of whom died. Of the 20 remaining patients, three were placed on a venoarterial ECMO regimen because of our early uncertainty about the efficacy of venovenous ECMO or because of technical constraints. All other patients (n = 17), including three with congenital diaphragmatic hernia, were supported with venovenous perfusion. No patient begun on a venovenous ECMO regimen required conversion to venoarterial bypass. Before ECMO, venovenous patients required an average dopamine dose of 16 micrograms/kg per minute and an average dobutamine dose of 6 micrograms/kg per minute. Of 15 patients studied before ECMO, three had significantly impaired contractility, and all had evidence of pulmonary hypertension on an echocardiogram. Mean blood pressure did not change while heart rate fell from 172 to 146 beats/min during the first 2 hours of ECMO and vasoactive drug doses were reduced. Of the 17 venovenous ECMO patients, 15 (88%) survived. We conclude that neonatal patients with severe hypoxia and substantial circulatory compromise can be effectively supported by venovenous ECMO in most cases.

Extracorporeal membrane oxygenation and indications for cardiopulmonary bypass in the neonate

Extracorporeal membrane oxygenation (ECMO) is a rescue technique used for term and near-term neonates who have respiratory failure that is unresponsive to conventional therapy. The complexity of the equipment necessitates intensive training of a specialized team before setting up an ECMO unit. An understanding of the physiology underlying ECMO and the criteria used for patient selection assists the nurse in identifying neonates who might benefit from the technique.

To-and-for extracorporeal lung assist (ECLA) through a single catheter-in premature goats as an experimental model of infant respiratory Insufficiency

A new to-and-fro V-V bypass extracorporeal lung assist (ECLA) through a single catheter as a blood access was investigated for its efficacy on six premature goats delivered by Cesarean section at a gestational age of 118 approximately 139 days as an experimental model of infant respiratory insufficiency, then applied to a human premature infant suffering from life threatening barotrauma that had developed from mechanical pulmonary ventilation. The extracorporeal bypass flow and the gas flow to the artificial membrane lung were controlled to keep Pa(O)(2) above 40 mmHg and Pa(CO)(2) within normal limits. The neonate's own lungs were treated with a continuous positive airway pressure of 5 approximately 12 cmH(2)O, apneic oxygenation or IMV. Two goats weighing 1250 g and 700 g died 2 approximately 2.5 hours after birth from severe circulatory distress. However, the other four neonates which were heavier than 2000 g, were successfully weaned from ECLA, and three of these could be weaned from mechanical ventilation as well. A human infant also survived and was weaned from ECLA on the third day.(Tanoue T, Terasaki H, Sadanaga M et al.: To-and-fro extracorporeal lung assist (ECLA) through a single catheter-in premature goats as an experimental model of infant respiratory insufficiency.

Venovenous extracorporeal membrane oxygenation (ECMO) using a double-lumen cannula

Extracorporeal membrane oxygenation (ECMO) can support neonates with severe respiratory failure. Currently, the most common application of ECMO requires venoarterial access. Venovenous (VV) ECMO is desirable to avoid common carotid artery ligation. However, the best technique of venous access for VV ECMO is not established. Using a single cannula with a double-lumen (DLC) in the right atrium for simultaneous drainage and infusion of blood, VV ECMO provided total respiratory support for six apneic puppies for 3 h each. Mean systemic arterial oxygenation was lower with DLC VV (50 torr) compared to VA ECMO (247 torr), but a physiologic pH (mean 7.34) was maintained on DLC VV bypass. Higher mean bypass flow was required on DLC VV (124 ml/kg/min) compared to VA flow (101 ml/kg/min) because of recirculation of oxygenated blood. The position of the DLC in the right atrium needed to be closely monitored. Hemorrhage was noted in the myocardium after use of DLC VV ECMO.

Extracorporeal membrane oxygenation (ECMO) in neonatal respiratory failure. 100 cases

Extracorporeal membrane oxygenation (ECMO) was used in the treatment of 100 newborn infants with respiratory failure in three phases: Phase I (50 moribund patients to determine safety, efficacy, and risks); Phase II (30 high risk patients to compare ECMO to conventional ventilation); and Phase III (20 moderate to high risk patients, the current protocol). Seventy-two patients survived including 54% in Phase I, 90% in Phase II, and 90% in Phase III. The major complication was intracranial bleeding, which occurred in 89% of premature infants (less than 35 weeks) and 15% of full-term infants. Best survival results were in persistent fetal circulation (10, 10 survived), followed by congenital diaphragmatic hernia (9, 7 survived), meconium aspiration (44, 37 survived), respiratory distress syndrome (26, 13 survived), and sepsis (8, 3 survived). There were seven late deaths; in follow-up, 63% are normal or near normal, 17% had moderate to severe central nervous system dysfunction, and 8% had severe pulmonary dysfunction. ECMO is now used in several neonatal centers as the treatment of choice for full-term infants with respiratory failure that is unresponsive to conventional management. The success of this technique establishes prolonged extracorporeal circulation as a definitive means of treatment in reversible vital organ failure.

Venovenous perfusion in ECMO for newborn respiratory insufficiency. A clinical comparison with venoarterial perfusion

Venoarterial (VA) extracorporeal membrane oxygenation (ECMO) has been successful in the treatment of newborns less than 1 week of age and greater than 2000 gm birthweight with respiratory failure resistant to current medical and surgical management. While VA ECMO supports the heart as well as the lungs, it has the disadvantage of requiring carotid artery ligation and the possibility of perfusing air bubbles or particles into the arterial tree. We have treated 11 newborns with respiratory failure with venovenous (VV) ECMO returning the oxygenated blood to a cannula in the distal iliac vein. We compared these patients with 16 patients treated during the same period of time with VA ECMO. Three of the 11 VV patients required conversion to VA ECMO because of inadequate oxygenation and unstable hemodynamic situations. Ten of the 11 VV patients survived. Eleven of the 16 VA patients survived. The better survival in these patients treated with VV ECMO is attributed to their more favorable initial condition compared to patients treated with VA ECMO. The disadvantages of VV ECMO include a longer operative time to place the cannulas, groin wound problems, and persistent leg swelling along with the necessity to convert some patients to VA ECMO. Although this experience demonstrates that newborns with severe respiratory failure can be supported with VV ECMO, the complications and lack of practical advantages over VA lead us to recommend VA ECMO for routine clinical use at present.