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

A prospective, multicenter, randomized study of high versus low positive end-expiratory pressure during extracorporeal membrane oxygenation

To test the hypothesis that increased positive end-expiratory pressure (PEEP) could prevent deterioration of pulmonary function and lead to more rapid recovery of lung function, we randomly assigned 74 patients undergoing extracorporeal membrane oxygenation (ECMO) at four centers to receive either high (12 to 14 cm H2O) or low (3 to 5 cm H2O) PEEP. The two groups were similar in terms of weight, gestational age, diagnosis, and pre-ECMO course. All other aspects of care were identical. Dynamic lung compliance was measured at baseline and every 12 hours. Radiographs of the chest were obtained daily. Survival rates were similar in the two groups: 36 of 40 for low PEEP and 34 of 34 for high PEEP. The duration of ECMO therapy was 97.4 +/- 36.3 hours in the high-PEEP group and 131.8 +/- 54.5 hours in the low-PEEP group (p less than 0.01). Dynamic lung compliance throughout the first 72 hours of ECMO was significantly higher in patients receiving high PEEP. Radiographic appearance of the lungs correlated well with lung compliance: patients receiving high PEEP had significant deterioration of the radiographic score less frequently than those receiving low PEEP. High PEEP also was associated with significantly fewer complications. We conclude that PEEP of 12 to 14 cm H2O safely prevents deterioration of pulmonary function during ECMO and results in more rapid lung recovery than traditional lung management with low PEEP.

The predictive value of head ultrasound in the ECMO candidate

Cranial ultrasound (US) examination is the screening technique of choice for assessing preexisting neurological damage in potential neonatal extracorporeal membrane oxygenation (ECMO) candidates. Currently, US evidence of intracranial hemorrhage greater than grade I in severity is a contraindication to ECMO at this ECMO center. In the current study, radiological findings were reviewed in 129 consecutive neonatal ECMO cases in an attempt to identify which pre-ECMO US findings were associated with the development of subsequent intracranial complications while on ECMO. Pre-ECMO head US, post-ECMO head US, and head computed tomography (CT) scans were reviewed retrospectively by one radiology team. Ventricular, parenchymal, and extraaxial fluid abnormalities were recorded for each case. Pre-ECMO US findings were then correlated with the subsequent development of significant intracranial radiological abnormalities noted on post-ECMO studies as well as with clinical data regarding ECMO course and outcome. Results showed that infants with evidence of severe edema or periventricular leukomalacia on pre-ECMO imaging had a 63% incidence of subsequent major intracranial complications. This represents a significantly higher risk than in candidates with a normal examination or evidence of grade I intracranial hemorrhage, subependymal cysts, or mild edema. These results suggest that infants with sonographic evidence of ischemic or anoxic damage on pre-ECMO US are at high risk for the development of significant intracranial complications if ECMO therapy is instituted.

Severe myocardial dysfunction during extracorporeal membrane oxygenation

Of the 102 neonates with respiratory failure supported with extracorporeal membrane oxygenation (ECMO) at this institution between 1984 and 1987, 8 patients developed severe myocardial dysfunction that was noted shortly after onset of bypass. The neonates in the cardiac dysfunction group were more hypoxic (average PaO2 = 26 +/- 8 mm Hg v 41 +/- 19 mm Hg, P less than .01) in the immediate pre-ECMO period. Seventy-five percent were unstable hemodynamically (6 hypotensive, 3 bradycardic, 2 sustained cardiac arrest, 4 required epinephrine pressor support). On ECMO, 5 of the 8 neonates developed an ischemic cardiomyopathy that lasted for less than 24 hours and resolved without therapeutic intervention. In the other 3 cases, prolonged periods of dysfunction were noted and afterload reduction through administration of tolazoline or hydralazine was beneficial. These 8 patients serve to demonstrate the reversible nature of postischemic cardiac dysfunction in patients on ECMO and in the neonatal population in general.

Serial measurement of pulmonary mechanics assists in weaning from extracorporeal membrane oxygenation in neonates with respiratory failure

Extracorporeal membrane oxygenation (ECMO) is a highly invasive therapy for intractable neonatal respiratory failure, and serious complications may occur with increasing duration of bypass. Weaning from bypass is empirical at present. Thus, there is a need to accurately predict when infants can be successfully decannulated. We hypothesized that pulmonary mechanics would reflect lung recovery and, therefore, predict successful weaning from ECMO. We measured pulmonary mechanics daily in 22 neonates, at gestational age of 37.8 +/- 0.6 weeks (SE) requiring ECMO for severe respiratory failure (oxygen index 66 +/- 6). Pulmonary resistance (Rpul), dynamic compliance (Cdyn), and tidal volume (VT) were measured. Rpul did not predict lung recovery. Cdyn within 24 hours of starting ECMO was 0.3 +/- 0.04 ml/cm H2O. Cdyn within 24 hours of weaning from ECMO was 1.2 +/- 0.09 ml/cm H2O (p less than 0.001). All 22 infants had Cdyn greater than 0.6 ml/cm H2O at the time of decannulation, but four infants (20 percent) with Cdyn less than 0.6 ml/cm H2O could not be weaned from ECMO within 20 hours (p less than 0.01). Thus, a minimum Cdyn of 0.6 ml/cm H2O is associated with successful weaning from ECMO. Cdyn of 0.8 ml/cm H2O provided better overall discrimination between those who could be successfully weaned from ECMO. We conclude that serial measurement of dynamic pulmonary compliance predicts successful weaning from ECMO.

Pulmonary edema and fluid mobilization as determinants of the duration of ECMO support

The physiological variables that govern recovery of pulmonary function during neonatal extracorporeal membrane oxygenation (ECMO) remain poorly understood. We hypothesized that pulmonary hypertension (PHN) resolves soon after starting ECMO and that neonatal weight gain, pulmonary edema, and fluid mobilization are major determinants of recovery of pulmonary function and the ability to decrease ECMO support. To evaluate this, 17 consecutive neonates requiring ECMO for severe respiratory failure were reviewed. PHN was studied by daily echocardiography to assess the direction of ductal shunting. To evaluate fluid flux, pulmonary function, and edema during ECMO, we measured body weight, urine output, and ECMO flow every 12 hours. To evaluate pulmonary edema, serial chest radiographs obtained every 12 hours were randomly reviewed and scored by two radiologists with a semiquantitative chest radiograph index score (CRIS). By 25% of bypass time, PHN had resolved in all patients. However, at that time, weight had increased to 9.16% +/- 1.78% above birth weight, and the CRIS was 44% worse than the value just prior to ECMO. From 25% time on bypass, as urine output increased, patient weight and CRIS progressively decreased, allowing ECMO support to be weaned. At the time of discontinuation of ECMO support, weight had decreased to 2.0% +/- 1.3% above birth weight, and urine output remained steady at 3.0 +/- 0.3 mL/kg/h. Within 24 hours of stopping ECMO, the CRIS showed a 58% improvement compared to maximal scores during ECMO. We conclude that PHN decreases early in ECMO and that edema and its mobilization are important determinants of the improvement in pulmonary function and duration of ECMO.(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital diaphragmatic hernia: predictors of severity in the ECMO era

Infants with congenital diaphragmatic hernia (CDH) demonstrate a wide range of anatomic and physiologic abnormalities, making it difficult to compare the efficacy of new forms of therapy such as extracorporeal membrane oxygenation (ECMO) among institutions. This study was undertaken to determine whether any predictors of severity could be identified in the ECMO era. The charts of all patients with CDH treated at this institution since 1984, when ECMO became available. (n = 110), were reviewed. Infants were considered high risk and included in this study if they presented with respiratory distress within the first 6 hours of life (n = 94). In order to focus on predictors of pulmonary insufficiency, patients who died of nonpulmonary causes or had other significant congenital anomalies were excluded from this review, leaving 59 patients for analysis. All the infants during this period had intensive pharmacological and ventilatory support. When needed, ECMO was offered postoperatively from 1984 to 1987, and preoperatively from 1987 to the present. Forty-five of 59 had a best postductal PO2 (BPDPO2) greater than 100 mm Hg, and 41 of these responders survived (91%). Fourteen patients had a BPDPO2 less than 100 mm Hg and only one survived (7%) (P = .0001). Mean BPDPO2 between survivors with or without ECMO, and nonsurvivors were also significantly different (P = .001). To incorporate ventilatory information, an oxygenation/ventilation index was devised: [OVI = PO2/(mean airway pressure x respiratory rate) x 100]. Differences in OVI between these three groups were also significant. When analyzing the data by the method proposed by Bohn (PCO2 v VI), no correlation between ventilatory parameters and outcome was found.(ABSTRACT TRUNCATED AT 250 WORDS)

The impact of extracorporeal membrane support in the treatment of congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernia (CDH) treated by immediate surgical intervention and conventional ventilatory support have an overall poor survival. The potential of extracorporeal membrane oxygenation (ECMO) therapy to improve survival of infants with CDH remains controversial. Comparison was made in a single institution's pre-ECMO and post-ECMO survival statistics to establish efficacy of extracorporeal support for persistent pulmonary hypertension (PPH). This study was accomplished by stratifying patients by an oxygen index (OI). Sixty-eight patients were treated for CDH from 1977 to 1986 without ECMO. Fifty-eight patients underwent repair of CDH within the first 24 hours of life. Data could be retrieved for calculation of the OI in 46 patients. Nineteen patients developed an OI of 40 or greater; one survived (5%). Three of 27 patients with an OI less than 40 died (OIs = 34, 38, and 38). Thirty-one patients were treated from 1987 to 1989 and none were excluded from ECMO based on a minimum PO2. Fifteen had an OI less than 40 (range, 1 to 38), were treated conventionally, and 13 survived (87%). Sixteen patients had an OI greater than 40 and 13 qualified for ECMO. Nine of 13 survived (69%). Comparing pre-ECMO and post-ECMO survival for infants with an OI of 40 or greater (5% v 69%), there is a significant improvement in survival when ECMO is used (P less than .001). ECMO support offers a strong adjunct in management of neonates with CDH who develop PPH.

Extracorporeal membrane oxygenation and neonatal respiratory failure: experience from the extracorporeal life support organization

Extracorporeal membrane oxygenation (ECMO) has rescued moribund infants with respiratory failure from a variety of causes. We report the experience from 58 United States and 7 overseas ECMO centers between 1980 and 1989. Voluntarily submitted data forms provided details of diagnosis, clinical condition, ECMO indications, morbidity, and mortality. Of 3,528 infants with a predicted mortality greater than 80% treated with ECMO, 83% survived. Entry diagnoses and aggregate survival were: meconium aspiration syndrome (MAS) 1,356 (93%), persistent pulmonary hypertension of the newborn (PPHN) 480 (83%); congenital diaphragmatic hernia (CDH) 585 (62%); hyaline membrane disease (HMD) 532 (84%); sepsis 416 (77%); and other 185 (77%). ECMO indications were a-AdO2 greater than 600 for 6 to 8 hours (22%), oxygenation index greater than 40 for 4 hours (18%), acute deterioration (14%), maximal therapy failure (34%), and barotrauma (1%). Annual survival improved over 9 years except for CDH, which decreased from 70% (1987) to 56% (1989) P less than .01). Survivors differed from non-survivors (P less than .05) by birth weight (greater than 2 kg), gestational age (greater than 37 weeks), entry diagnosis (MAS, PPHN, HMD, sepsis v CDH), inborn versus outborn, pre-ECMO pH, and ECMO duration. Technical complications in 25% of patients and medical complications in 75% adversely affected survival. Annual sepsis survival improved to 75% (1989) but had significantly greater complication rates (P less than .05) than other diagnoses. Multicenter data yield information not available from single institution experience. Although entry criteria and conventional therapy continue to evolve, ECMO currently improves survival from an estimated 20% to 83% overall. Individual prognosis depends on entry diagnosis, clinical condition, and complications.

Improvement in survival of patients with congenital diaphragmatic hernia utilizing a strategy of delayed repair after medical and/or extracorporeal membrane oxygenation stabilization

Patients with congenital diaphragmatic hernia (CDH) symptomatic at birth treated at this institution over the past 6 years were reviewed. The patients were divided into two chronological groups for analysis: group 1, consisting of 15 patients treated from January 1984 through October 1987, a period during which acute CDH was considered to be a surgical emergency; and group 2, comprising 20 patients treated from November 1987 through October 1989 using a management protocol of delayed repair following medical and/or extracorporeal membrane oxygenation (ECMO) stabilization. These two groups did not differ significantly in gestational age, birth weight, Apgar scores, hernia side, or age at admission. Group 2 had a longer mean interval from admission to repair (26.5 v 1.8 h, P = .01) and average age at repair (31.0 v 6.5 h, P = .02) than did group 1. Prosthetic closure of the diaphragmatic defect was required more frequently in group 2 then in group 1 (63% v 31%, P = .07). Survival in group 2 was significantly greater than in group 1 (55% v 20%, P = .04). Seven group 2 patients (35%) achieved a prerepair or pre-ECMO PO2 greater than 100 mm Hg and all survived; four of the 13 "nonresponders" also survived. ECMO was used in 11 group 2 patients with five survivors (45%); four of these patients underwent repair prior to ECMO and seven underwent repair while on ECMO.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of six ECMO selection criteria and analysis of factors influencing their accuracy

This study compared six extracorporeal membrane oxygenation (ECMO) selection criteria in 42 neonates and analyzed factors influencing the accuracy of outcome predictions. The sensitivity of the criteria in identifying fatal cases varied from 0.44 to 0.94 and the specificity of predictions of survival ranged from 0.42 to 0.69. The criterion having the highest sensitivity had the lowest specificity and conversely the criterion with the lowest sensitivity had the highest specificity. Overall accuracy of the criteria, as measured by the total number of correct outcome predictions, differed little among the criteria (23/42 to 27/42 correct predictions). Three factors influenced predictive accuracy: 1) a primary diagnosis of congenital diaphragmatic hernia (CDH) was associated with a greater mortality (P less than 0.001) and a significantly higher positive predictive value (PPV) for all criteria (P = 0.0009-0.012) than that seen in patients with other primary diagnoses; 2) calculating the alveolar-arterial oxygen gradient using an assumed, rather than measured barometric pressure, or estimating oxygenation index using a calculated, rather than a measured, mean airway pressure, increased false positive mortality predictions in non-CDH patients; and 3) requiring a peak inspiratory pressure (PIP) of at least 50 cm H2O in the definition of maximal medical management, rather than a PIP of 20-49 cm H2O, significantly increased the PPV for three of four criteria examined (P = 0.02-0.04). Awareness of these factors may facilitate the identification of neonates who need ECMO to survive.

Pulmonary mechanics and outcome of neonates on ECMO

Deciding when to wean neonates from extracorporal membrane oxygenation (ECMO) can be difficult. The usefulness of simple measurements of pulmonary mechanics e.g., dynamic compliance (Cdyn) has been questioned. We investigated the pulmonary mechanics of eight neonates using the interrupter technique, which allows the partitioning of pulmonary mechanics into compartments representing the conducting airways and more peripheral phenomena (viscoelastic properties and "pendelluft"). Three neonates required ECMO for a congenital diaphragmatic hernia (CDH), two for hyaline membrane disease (HMO), two for meconium aspiration syndrome (MAS), and one for pneumonia. All neonates with MAS, HMD, and pneumonia were successfully weaned from ECMO when their Cdyn was 0.3 mL/cmH2O/kg or greater [mean 0.34 +/- 0.06 (SEM)]. All three neonates with CDH died and their highest Cdyn was 0.21, 0.19, and 0.09 mL/cmH2O/kg respectively (mean, 0.16 +/- 0.037). The airway resistance (Raw) and the slower component of pressure change after interruption (delta Pdiff), a measure of the more peripheral phenomena of the lung, were not significantly different in those neonates who survived and those who did not. The values for delta Pdiff in all patients were higher than those in healthy neonates. However, the Raw was not different. This suggests that the major disturbance in pulmonary mechanics was distal to the conducting airways. Those neonates who were successfully weaned from ECMO had a significantly higher Cdyn 24-48 hours prior to decannulation. Considering the lung as a two-compartment model offers no advantages when compared to the one-compartment model for the prediction of the outcome of a neonate on ECMO.

Prognostic determinants in extracorporeal membrane oxygenation for respiratory failure in newborns

Extracorporeal membrane oxygenation (ECMO) is becoming an accepted therapeutic modality for newborn respiratory failure, but there is little information available regarding the prognostic determinants with this technique. One hundred thirty-five newborns treated with ECMO over a 4-year period were critically analyzed with regard to the influence that birth weight, gestational age, age at initiation of ECMO, best blood gases before ECMO, number of hours on ECMO, renal failure, intracerebral hemorrhage, and long-distance air transport had on survival. Infants with meconium aspiration and those undergoing long-distance transfer showed significant differences in blood gases before ECMO, with survivors having more normal pH and carbon dioxide tension values. Intracerebral hemorrhage and renal failure that developed during ECMO were grave prognostic signs, with few survivors in either group. These data show that ability to ventilate patients before ECMO, giving normal carbon dioxide tension and pH values, is an important prognostic sign in infants with meconium aspiration and undergoing long-distance transfer for ECMO, whereas renal failure and intracerebral hemorrhage are usually lethal complications of ECMO. Each center performing ECMO should continually reevaluate this invasive technique and its results and complications.

Extracorporeal membrane oxygenation and congenital diaphragmatic hernia: should any infant be excluded?

Mortality in infants with congenital diaphragmatic hernia (CDH) remains high despite improvements in neonatal and surgical care because many infants develop persistent pulmonary hypertension of the newborn (PPHN) following repair. Since 1984, extracorporeal membrane oxygenation (ECMO) has been used as rescue therapy in all infants (n = 25) with PPHN following CDH repair when conventional management failed, with an overall survival of 60%. Repair was performed in this hospital on 12 infants and in other hospitals in 13 infants transferred for consideration of ECMO after repair. Mortality was the same in the group repaired here and those transferred for ECMO. Although complications were frequent in the surviving group, they were successfully managed with nonoperative or operative therapy. Selective use of ECMO has been advocated in CDH patients based on various predictors of high mortality such as "best" PO2 postrepair less than 100 mm Hg, oxygenation index greater than 40, and ventilation index greater than 1,000 with PCO2 greater than 40. Seven surviving infants following ECMO would have been classified as unsalvageable by at least one parameter if selection criteria based on these parameters had been used. We conclude from this series that current predictors of high mortality in CDH patients are unreliable when ECMO is used. Surgeons caring for infants with CDH should consider the use of ECMO in all infants.

Congenital diaphragmatic hernia repair on ECMO

Congenital diaphragmatic hernia (CDH) with severe respiratory failure in the first few hours of life continues to be associated with significant mortality. Extracorporeal membrane oxygenation (ECMO) has been successfully used postoperatively to reverse the effects of severe pulmonary hypertension. Since 1984, ECMO has been required in 27 of the patients we treated with CDH. This report describes our experience with six very high-risk patients placed on ECMO prior to the operation who subsequently underwent repair of their diaphragmatic hernias while on ECMO. Two patients presented in extremis, unlikely to survive initial operative repair, and were placed on ECMO prior to the operation. All six patients had immediate respiratory distress after birth with mean Apgars of 2.3 and 3.7. The best pre-ECMO arterial blood gas (postductal) showed mean +/- SEM values of 6.97 +/- 0.1; PO2 = 54.8 +/- 5.9; PCO2 = 79.5 +/- 16.9. Immediately prior to ECMO, the mean +/- SEM ventilatory index (VI = rate x mean airway pressure) was 1,233 +/- 44, with a mean pH of 7.17 +/- 0.05; PO2 = 32 +/- 2.9; PCO2 = 59 +/- 5.3 and a mean AaDO2 of 622 +/- 4.8. The timing of the operative repair averaged 25 hours following initiation of ECMO. Three right-sided and three left-sided hernias were treated. Four were repaired through an abdominal approach, and two via thoracotomy; four required a Gortex patch closure. Postoperative bleeding was not a major problem in these heparinized patients. Four of these six patients survived, and follow-up of 2 months to 3 years shows no significant respiratory compromise.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary hypertension in neonatal cystic lung disease: survival following lobectomy and ECMO in two cases

Extracorporeal membrane oxygenation (ECMO) is an accepted form of therapy in the treatment of neonates with otherwise lethal persistent pulmonary hypertension related to meconium aspiration, congenital diaphragmatic hernia, and sepsis. This report concerns two neonates with congenital cystic lesions of the lung who developed severe pulmonary hypertension and were salvaged with lobectomy and ECMO. These cases present an additional group of patients in whom ECMO may be a life-saving measure.

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.

Preliminary report: extracorporeal lung support for neonatal acute respiratory failure

A technique for ventilatory support of life-threatening neonatal acute respiratory failure by use of apnoeic oxygenation and low-frequency positive-pressure ventilation, with extracorporeal membrane CO2 removal through a single-cannula perfusion circuit, is described. 20 severely ill babies with respiratory failure were treated with this technique, 17 of whom survived with no clinical evidence of pulmonary handicap or neurological deficit at discharge from hospital. All 10 patients followed up at 6 months showed normal growth and development.

Recent experience with diaphragmatic hernia and ECMO

In the past 4 years at the Medical College of Georgia, a total of 74 patients underwent extracorporeal membrane oxygenation (ECMO) with 62 (84%) survivors. Forty-seven of these infants had meconium aspiration syndrome and 11 had diaphragmatic hernia. The use of ECMO, when indicated, after reduction and repair of the diaphragmatic hernia, results in normal oxygen delivery, allows time for pulmonary maturation, and increases survival. A total of 27 referrals for diaphragmatic hernia were studied. Six infants had surgical repair and did not require ECMO. Eleven patients, after surgical repair, were treated with ECMO and seven survived. More importantly 10 patients died before the use of ECMO. Six infants died either before or during transport from referring hospitals and four died while in the delivery room or neonatal unit before ECMO. Of these 10 infants, eight were potential candidates for ECMO. Thirteen of the twenty-seven (48%) infants survived. Seven of eleven (64%) infants who received the benefit of ECMO survived. Eight infants who met the criteria for ECMO died before its use. Had ECMO been used in those eight infants, our data suggests that at least four may have survived. The data from this report support the concept that infants undergoing surgical repair of diaphragmatic hernia, when ECMO is not available, should be referred to an ECMO center in the early postoperative period. Furthermore infants with prenatal diagnosis of diaphragmatic hernia should be delivered at a center where surgical as well as ECMO expertise are available.

Ventilation parameters and arterial blood gases as a prediction of hypoplasia in congenital diaphragmatic hernia

Attempts to predict the degree of pulmonary hypoplasia associated with congenital diaphragmatic hernia have been made by evaluating the ventilation parameters and the arterial blood gasses of these patients. A CO2 index as a predictor of outcome, which correlates the PaCO2 with the ventilation index, was recently proposed. However, in this study the postductal PaO2 was a better predictor of survival. And the so-called "honeymoon period" was a better indicator of the efficacy of extracorporeal membrane oxygenation (ECMO) than the CO2 index. Nineteen patients were evaluated; 11 were treated with ECMO, and eight were not considered suitable for ECMO.

Incidence of hypertension in infants on extracorporeal membrane oxygenation

Systemic hypertension has been associated with extracorporeal membrane oxygenation (ECMO) applied in neonatal respiratory failure. To determine the incidence of ECMO-related hypertension, we reviewed blood pressure measurements from indwelling aortic catheters in 31 infants consecutively placed on ECMO. Systemic hypertension (systolic blood pressures greater than 100 mm Hg for 4 or more consecutive hours) developed in 18 of the 31. Causes investigated included the roles of renin secretion, sodium, and colloid loads. There was no evidence of increased plasma renin activities in hypertensive infants (H), when compared with their own pre-ECMO controls or with the nonhypertensive infants (NH). Sodium and colloid loads and their rates of delivery were not different between H and NH. No consistent duration of ECMO was clearly associated with development of hypertension (mean time on ECMO at onset of hypertension, 43.8 +/- 38.5 hours; range, 1 to 142 hours). Demographic information was not statistically significant. Contrary to previous reports, H did not seem predisposed to an increased incidence of intracranial hemorrhage. Development of hypertension during ECMO is not related to increased plasma renin activity, sodium or colloid loads, or their rates of infusion.

Compliance, alveolar-arterial oxygen difference, and oxygenation index changes in patients managed with extracorporeal membrane oxygenation

Eighteen patients with meconium aspiration syndrome who failed conventional management were treated with extracorporeal membrane oxygenation (ECMO) for reversible respiratory failure. Dynamic lung compliance measurements were made prior to, during, and after ECMO support. P(A-a)O2 and oxygenation index (OI) measurements were calculated prior to and after ECMO support. Lung compliance decreased significantly comparing before-ECMO to during-ECMO, and increased significantly comparing during- to after-ECMO, but not comparing before- to after-ECMO measurements. P(A-a)O2 and OI decreased significantly from before to after ECMO. The improvement in oxygenation allowing removal from ECMO does not appear to be related to improved pulmonary mechanics, but may rather be secondary to increased effective pulmonary capillary blood flow.

Pulmonary lobar transplantation in neonatal swine: a model for treatment of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) babies born with severe pulmonary hypoplasia are unsalvageable despite maximal therapy including extracorporeal membrane oxygenation (ECMO). Lung transplantation is a potential treatment for these otherwise doomed infants using ECMO as a bridge to transplantation. Cadaveric, or living related donation of a more mature reduced size lung (pulmonary lobe or segment) may help solve the critical donor shortage problem. We evaluated the physiological response of mature left lower lobe (LLL) transplants in neonatal swine with the hemodynamic conditions of CDH simulated by occlusion of the right pulmonary artery (PA), and also studied the pulmonary function of the mature lobar graft compared with the neonatal lung. LLL transplantation was well tolerated and resulted in minimal alteration in hemodynamic parameters. The response to right PA occlusion was similar pre- and posttransplantation with a fall in cardiac output and a significant rise in pulmonary vascular resistance. Compared with the contralateral native lung, the lobar graft was preferentially ventilated with resultant higher pH (7.65 +/- 0.17 v 7.41 +/- 0.08, P less than .01) and lower pCO2 (17 +/- 6 v 36 +/- 5, P less than .001). The more mature lobar graft was preferentially ventilated due to the increased compliance compared with the neonatal right lung (8.16 +/- 1.28 v 5.48 +/- 0.82 mL/cm, P less than .0001). Reduced size lung transplantation is technically feasible and may help solve the donor problem for severe CDH neonates for whom no effective therapy is currently available.

Correction of congenital diaphragmatic hernia in utero, V. Initial clinical experience

Review of our experience with 45 cases of prenatally diagnosed congenital diaphragmatic hernia (CDH) confirms that most fetuses (77%) will not survive despite optimal pre- and postnatal care. Polyhydramnios, associated anomalies, early diagnosis, and a large volume of herniated viscera (including liver) are associated with a particularly dismal prognosis. After extensive experimental work demonstrated the efficacy, feasibility, and safety of repair in utero, we attempted to salvage six highly selected fetuses with severe CDH by open fetal surgery. Five had liver incarcerated in the chest: three died at operation because attempts to reduce the liver compromised umbilical venous return. In one, a Goretex diaphragm was constructed around the liver, but the baby died after birth. The last two fetuses, one with incarcerated liver, were successfully repaired. Both demonstrated rapid growth of the lung in utero, had surprisingly good lung function after birth despite prematurity, had the abdominal patch removed at 2 weeks, and subsequently died of nonpulmonary problems (an unrelated nursery accident in one and intestinal complications in the other). The only maternal complication was amniotic fluid leak and preterm labor. All six women are well and four have had subsequent normal children. From this phase I experience, we conclude that fetal surgery appears safe for the mother and her reproductive potential, that fetal CDH repair is feasible in selected cases, and that the fetal lung responds quickly after decompression. However, fetal repair remains a formidable technical challenge.

Decreasing blood donor exposure in neonates on extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) has been successful treatment (80% survival) in over 2,000 neonates with severe respiratory failure (80% predicted mortality without ECMO). Neonates on ECMO require frequent blood product replacement, which increases donor exposure (DE) and the risk of transfusion related complications. Successful, widespread usage of ECMO in neonatal respiratory failure is placing increased numbers of surviving infants at risk for acute and long-term transfusion related problems. We assessed DE rates in 21 consecutive neonatal ECMO survivors. In the first 12 patients packed red blood cell (PRBC) transfusions were administered as 10 mL/kg body weight for hematocrit less than 45%. PRBC exchange transfusions were used in patients with hematocrit less than 45% and hypervolemia. Fresh frozen plasma (FFP) and cryoprecipitate (CRYO) infusions were used empirically for evidence of hemorrhage. DE rates (donors per ECMO day, mean +/- SD) were: PRBC (2.8 +/- 0.6), FFP/CRYO (0.5 +/- 0.7), and platelet (2.0 +/- 1.0), with a total donor exposure rate of 5.3 +/- 2.0 donors per ECMO day. Mean duration of ECMO was 4.6 +/- 2.0 days and total DE per infant was 22.8 +/- 9.5 donors per ECMO run. In a protocol (n = 9) to minimize DE risks, exchange transfusions were eliminated and PRBC transfusion volumes were increased to 15 mL/kg. Empiric use of FFP and CRYO was discontinued. The blood bank divided standard units of PRBCs into four aliquots and dispensed each aliquot sequentially before dispensing blood from another unit.(ABSTRACT TRUNCATED AT 250 WORDS)

Mediastinal hemorrhage during extracorporeal membrane oxygenation

A case of mediastinal hemorrhage along with hemorrhage into a pneumatocele while on extracorporeal membrane oxygenation (ECMO) is presented. Computerized tomography of the chest was utilized to support the diagnosis. Barotrauma to the lungs best explains the inciting event that allowed the hemorrhage to occur once the patient was heparinized for ECMO. This complication serves to point out the importance of commencing early ECMO support before widespread pulmonary and mediastinal barotrauma develops.

The significance of ductal shunting during extracorporeal membrane oxygenation

The purpose of this study was to evaluate the significance and direction of shunts at the level of the foramen ovale or ductus arteriosus in full-term newborns with neonatal respiratory failure who were placed on extracorporeal membrane oxygenation (ECMO). A decrease in left ventricular dimension was expected when infants were placed on ECMO but did not occur. A left-to-right shunt was demonstrated at the ductal level in nine of 12 infants early in the course of ECMO before pulmonary resistance decreased. Presumably, the lack of change in the left ventricular dimension when infants were placed on bypass was due to a left-to-right shunt at the ductal level with ductal flow replacing the right heart output, being drawn into the bypass circuit.

Fetal diaphragmatic hernia: ultrasound diagnosis and clinical outcome in 38 cases

A previously published survey has evaluated the natural history and clinical outcome of fetal diaphragmatic hernia (CDH) in 94 cases. This study showed that the prenatal diagnosis is accurate, the mortality is high (80%), and polyhydramnios is a prenatal predictor of poor clinical outcome. As a follow-up study, 38 consecutive cases of CDH diagnosed in utero were evaluated and treated by the same surgical team. This permitted detailed assessment of prognostic factors and evaluation of the impact of extracorporeal membrane oxygenation (ECMO) on outcome. We found the following. (1) Survival is poor despite optimal postnatal therapy including ECMO. (2) Polyhydramnios is both a common prenatal marker for CDH (present in 69% of fetuses) and a predictor for poor clinical outcome (only 18% survival), but tends to occur after the second trimester. (3) Amniocentesis is indicated to rule out chromosomal abnormalities that were present in 16% of fetuses. (4) All 14 fetuses diagnosed prior to 25 weeks' gestation died. Improved postnatal therapy or surgical intervention before birth will be necessary to salvage the CDH fetus with an early gestational diagnosis or associated polyhydramnios.

Tension pneumothorax during extracorporeal membrane oxygenation

Life-threatening tension pneumothorax in neonates on extracorporeal membrane oxygenation (ECMO) has been associated with an increase in arterial oxygen tension and a decrease in peripheral perfusion, followed by a decrease in ECMO flow with progressive hemodynamic deterioration. To investigate this triad, chest tubes were placed bilaterally in 9 dogs to allow injection of air to produce tension pneumothorax. Six dogs were subsequently placed on standard venoarterial ECMO before the reinduction of tension pneumothorax. Measured values included arterial pulse pressure, inferior vena cava pressure, systemic arterial blood gases, peripheral arterial oxygen saturation, mixed venous oxygen saturation, and left heart cardiac output. Oxygen delivery was calculated from directly measured values. Each of the 6 dogs on ECMO demonstrated the triad of increased arterial oxygen tension (92 +/- 7 to 325 +/- 20 mm Hg; p less than 0.05), decreased peripheral perfusion (as evidenced by a decrease in pulse pressure from 55 +/- 4 to 31 +/- 5 mm Hg; p less than 0.05), and decreased mixed venous oxygen saturation (71% +/- 3% to 22% +/- 2% saturation; p less than 0.05) followed by a lower ECMO flow with progressive hemodynamic deterioration (oxygen delivery decreased from 285 +/- 11 to 111 +/- 12 mL/min; p less than 0.05). Aspiration of the intrathoracic air allowed return to baseline ECMO flow and hemodynamic stability in all dogs. The triad of increased arterial oxygen tension and decreased peripheral perfusion (as evidenced by a lower arterial pulse pressure and lower mixed venous oxygen saturation) followed by decreased ECMO flow with progressive hemodynamic deterioration consistently appears when tension pneumothorax occurs on ECMO.

A randomized comparison of total extracorporeal CO2 removal with conventional mechanical ventilation in experimental hyaline membrane disease

Apnoeic oxygenation (AO) combined with extracorporeal CO2 removal (ECCO2R), using venovenous perfusion across a membrane area of 0.1 m2 has been shown to be feasible in six healthy anaesthetized rabbits. In a further twelve rabbits, ECCO2R has been randomly compared with conventional mechanical ventilation (CMV) following saline lavage to induce respiratory failure. Blood gases were maintained for up to 6 h within the same range (PaO2 = 8-20 kPa, PaCO2 = 4-6 kPa) in two groups of six by varying airway pressures and the oxygen fraction delivered either to the membrane lung (ECCO2R group) or to the ventilator (CMV group). The influence of single hourly sustained inflations (SI) on oxygenation was studied. ECCO2R subjects remained stable and survived. CMV subjects deteriorated and had 80% mortality. Hyaline membranes were absent from ECCO2R subjects and present in all CMV subjects. The response to SI suggests that a lung volume recruitment is maintained during AO for up to 1 h but is ineffective during CMV.

Advanced techniques in thoracic trauma

Technologic aid is available for the three central problems of hemorrhage, lung damage, and cardiac damage. Autotransfusion, new modes of ventilator support, extracorporeal oxygenation, balloon pumping, and left ventricular assist are available for the trauma patient. The author explains these new devices and their role in thoracic trauma cases.

Reversal of mortality for congenital diaphragmatic hernia with ECMO

Extracorporeal Membrane Oxygenation (ECMO) has been available to neonates with respiratory failure at the University of Michigan School of Medicine since June 1981. In order to evaluate the impact of this type of pulmonary support, a retrospective analysis of 50 neonates with posterolateral congenital diaphragmatic hernia (CDH) who were symptomatic during the first hour of life and were treated between June 1974 and December 1987 was carried out. The patients were divided into two groups, those treated before June 1981 (16 patients) and those treated after June 1981 (34 patients). Overall survival improved from 50% (eight of 16 patients) during the pre-ECMO era to 76% (26 of 34 patients) during the post-ECMO period (p = 0.06). During the period after June 1981, 21 neonates were unresponsive to conventional therapy and were therefore considered for ECMO. Failure of conventional therapy was defined as acute clinical deterioration with an expected mortality of greater than 80% based on an objective formula previously reported. Six patients were excluded on the basis of specific contraindications to ECMO. Thirteen of 15 infants (87%) supported with ECMO survived. Three patients treated before 1981 met criteria for ECMO; all three died while receiving treatment using conventional therapy. These survival differences are significant (p less than 0.01). In addition, the survival of 87% for the infants treated with ECMO versus the expected mortality of greater than 80% for these same patients when treated with conventional therapy is highly significant (p less than 0.005). Based on this data, ECMO appears to be a successful, reliable, and safe method of respiratory support for selected, critically ill infants with CDH.

Neurosonographic findings in infants treated by extracorporeal membrane oxygenation (ECMO)

Extracorporeal membrane oxygenation (ECMO) is an approved therapy for some neonates who have respiratory failure that is due to hyaline membrane disease, meconium aspiration, persistent pulmonary hypertension, congenital diaphragmatic hernia, or sepsis. The major complication of this therapy is hemorrhage, with intracranial hemorrhage having the highest morbidity and mortality. Seizures, incisional bleeding and bleeding in the pleural space, hypoxic-ischemic encephalopathy, renal failure, and cardiovascular complications account for most of the other complications. Cranial sonography provides an ideal imaging modality for baseline evaluation and daily follow-up; however, computed tomography and magnetic resonance imaging, because of better sensitivity, are important for assessment after ECMO. The changes in intracranial blood flow related to ECMO can be noninvasively evaluated by Doppler ultrasound modalities.

Successful gastrorrhaphy on ECMO

From April 1985 to November 1987, over 100 infants were evaluated for extracorporeal membrane oxygenation (ECMO) in the treatment of respiratory failure. Of these infants, 40 underwent ECMO after failure of conventional treatment. Four developed gastroduodenal perforations. One developed a perforation prior to going on ECMO and died after several hours on ECMO, one developed a perforation while being treated conservatively for respiratory failure that never required ECMO, and two developed perforations requiring laparotomy while on ECMO. These two infants constitute the first report of successful gastrorrhaphy in infants while being supported by ECMO and anticoagulation with heparin. Particular measures helpful in the management of these infants included near-total cardiopulmonary bypass, reduction of the activated clotting time to 170 to 200, transverse abdominal incision for exposure, use of electrocautery, appropriate drainage of the operative site, insertion of a gastrostomy for gastric decompression and irrigation, rapid weaning from ECMO as soon as respiratory support could be provided by conventional methods, and the use of massive blood and platelet transfusions. In summary, 33 of 40 infants undergoing ECMO survived. Furthermore, two of the three infants with intestinal perforation who underwent ECMO have survived without significant short-term sequelae, and are 24 and 30 months of age, respectively. Therefore, we believe that despite severe respiratory failure requiring ECMO and anticoagulation with heparin, infants with intestinal perforation can be managed surgically with anticipated survival and good long-term prognosis.