Inter-hospital transport of neonatal patients on extracorporeal membrane oxygenation: mobile-ECMO.

OBJECTIVE: To describe the equipment, personnel requirements, training, management techniques, and logistic problems encountered in the design and implementation of a mobile extracorporeal membrane oxygenation (ECMO) program. DESIGN: This is a report of a technique for the transport of patients on ECMO and a description of our retrospective case series. SETTINGS: The study was conducted at a regional referral children's hospital and ECMO unit. PATIENTS: Thirteen neonatal medical patients with acute respiratory failure were transported with mobile-ECMO. RESULTS: Over a 24-month period, we transported 13 neonatal patients with mobile-ECMO. The reason for transport with mobile-ECMO was inability to convert from high-frequency ventilation (4 of 13), patient already on ECMO (1 of 13), and patient deemed too unstable for conventional transport (8 of 13). Eleven of the 13 patients were transported from other ECMO centers. Of the 13, 9 survived. No major complications during transport were reported for any of the patients. Follow-up data were available on all nine survivors of neonatal mobile-ECMO. Eight of these had normal magnetic resonance imaging scans of the brain; the ninth had a small hemorrhage in the left cerebellum. CONCLUSION: Our limited series shows that patients can be safely transported with mobile-ECMO. This program does not replace the early appropriate transfer for ECMO-eligible patients to an ECMO center.

Assessment of hemodynamic status in the intensive care unit immediately after closure of ventricular septal defect.

Hemodynamic values measured 12 to 24 hours postoperatively in the intensive care unit (ICU) were compared with those measured at a later cardiac catheterization in 68 patients after closure of ventricular septal defect (VSD). A pulmonary arterial (PA) saturation of more than 80% or a pulmonary to systemic blood flow ratio (Qp:Qs) greater than 1.5 in the ICU were sensitive indicators for identifying patients at risk of having a hemodynamically significant residual left-to-right shunt (Qp:Qs greater than 1.5) at catheterization. Measurement of PA pressure in the ICU was a useful predictor of PA pressure at catheterization. In the absence of factors known to alter PA pressure, measurement of PA pressure in the ICU overestimates what it will be at a subsequent cardiac catheterization. Early assessment of hemodynamics after closure of VSD is useful in identifying patients at risk of having hemodynamically significant residual VSD and those who may have persistent PA hypertension.

Early assessment of hemodynamic status after repair of tetralogy of Fallot: a comparison of 24 hour (intensive care unit) and 1 year postoperative data in 98 patients.

Hemodynamic data obtained in the intensive care unit, immediately after repair of tetralogy of Fallot, were compared with measurements obtained at 1 year postoperative catheterization in 98 infants and children. Eight of 12 patients who had pulmonary artery oxygen saturation of 80% or greater in the intensive care unit had a pulmonary to systemic flow ratio greater than 1.5 at catheterization; all 79 patients who had a pulmonary artery oxygen saturation of ess than 80% in the intensive care unit had a pulmonary to systemic flow ratio of 1.5 or less at catheterization. Five of six patients who had a right ventricular outflow tract pressure gradient greater than 40 mm Hg in the intensive care unit had a gradient greater than 40 mm Hg at catheterization; 7 of 61 patients who had a right ventricular outflow tract gradient of 40 mm Hg or less in the intensive care unit had a gradient greater than 40 mm Hg at catheterization. The addition of measurements of right ventricular pressure and the right ventricular to systemic arterial pressure ratio in the intensive care unit did not improve sensitivity in identifying patients with a right ventricular outflow tract gradient greater than 40 mm Hg at catheterization. Intensive care unit measurement of pulmonary artery oxygen saturation is valuable for determining the presence or absence of a significant left to right shunt after repair of tetralogy of Fallot and should be considered an adjunct to patient management. Intensive care unit measurement of the right ventricular outflow tract gradient identifies patients with a significant right ventricular outflow tract gradient at catheterization but is not highly sensitive.

Pulmonary hypertension and arterial changes in calves with a systemic-to-left pulmonary artery connection.

The pathogenic mechanisms by which increased pressure and flow lead to pulmonary vascular disease are poorly understood, especially in newborns. To study the pathophysiological correlations and timing of the development of structural changes in response to high flow in nonhypoxic neonates, a model of high pulmonary flow was developed in newborn calves by anastomosis of the isolated left pulmonary artery (LPA) to the aorta. LPA pressure and flow increased acutely. LPA pressure reached near-systemic levels by 10 wk, whereas LPA flow was maximally increased at 1 mo before decreasing in several calves. Right pulmonary arterial pressure remained normal, and ventricular hypertrophy did not develop. Morphometric evaluation of the left lung demonstrated decreased arteriolar diameter, increased medial thickness, muscularization of arterioles at the bronchoalveolar junction, luminal obliteration of small arteries, and dilation lesions. The LPA pressure and vascular changes were greater and developed over a shorter time period than did prior models of nonhypoxic flow-induced pulmonary vascular changes. Lesser degrees of decreased arteriolar diameter and muscularization of small vessels were seen in the right lung, indicating a difference in the vascular response to moderately increased flow vs. increased pressure and flow. Thus, calves with an isolated LPA-to-aortic anastomosis simulate the hemodynamic and pulmonary vascular changes seen in newborns with congenital heart defects. Such calves may serve as models to assess effects of mechanical stresses on a newborn's vasculature.

Mobile extracorporeal membrane oxygenation.

Transport of critically ill neonates in need of extracorporeal membrane oxygenation can be risky. Their extreme cardiorespiratory instability may delay or even preclude conventional transport to an extracorporeal membrane oxygenation center. We report the use of a UH-1 helicopter specially adapted for mobile extracorporeal membrane oxygenation support to transport a critically ill neonate.

Extracorporeal membrane oxygenation for cardiac failure after congenital heart operation.

Despite continuing improvement in myocardial protection and surgical technique, the repair of complex congenital heart lesions can result in cardiopulmonary compromise refractory to conventional therapy. In a 29-month period, 24 patients (aged 14 hours to 6 years) were treated with extracorporeal membrane oxygenation (ECMO) 28 times for profound cardiopulmonary failure. Four patients required ECMO after each of two cardiopulmonary bypass procedures. Seventeen patients required ECMO to be initiated in the operating room: 12 (71%) were weaned successfully from ECMO, and 8 (47%) survived. Seven patients had ECMO initiated in the intensive care unit: 6 (86%) were weaned, and 5 (71%) survived. Serial echocardiograms demonstrated substantial recovery of cardiac function in 18 of 21 instances (86%) of ventricular failure from myocardial dysfunction. Overall, 18 of 24 patients (75%) were successfully weaned from ECMO including all 4 who underwent 2 ECMO treatments. We conclude that ECMO can successfully salvage children who have serious cardiopulmonary failure immediately after a congenital heart operation and that long-term survival is possible after two ECMO treatments.

Trouble shooting the extracorporeal membrane oxygenator circuit and patient.

Patients requiring extracorporeal membrane oxygenation (ECMO) often become totally dependent on the mechanical life support. The Extracorporeal Life Support Organization (ELSO) reports 2486 incidents of mechanical complications in 5905 ECMO supports. To help decrease the number of mechanical complications, an active quality assurance program was initiated at our institution. This resulted in identification of only 14 incidents of mechanical complications in 100 patients (neonate, pediatric, adult, and cardiac). Techniques for dealing with problems such as loss of roller pump occlusion, changing out of the membrane lung or heat exchanger without interrupting ECMO support, venous air lock, tamponade, emergency transfusion, and other situations were generated into written policies and procedures. We routinely review and practice problem solving techniques with specific emphasis on monitoring patient hemodynamics and appearance. We conclude that written policies and procedures, "water drills," and continuing education can be beneficial in early recognition, intervention, and/or prevention of ECMO mechanical complications.

Extracorporeal life support of neonates with congenital cardiac defects: techniques used during cardiac catheterization and surgery.

Neonatal patients with congenital cardiac defects require proper diagnosis often by cardiac catheterization before surgical repair. In our institution, patients whose echocardiograms reveal surgically correctable lesions, but who are severely decompensated, have been placed on Extracorporeal Life Support (ECLS) prior to catheterization or surgery. Subsequent management of ECLS and cardiopulmonary bypass (CPB) are dictated by the surgical procedure. Hypothermia can be utilized while on ECLS to facilitate low-flow CPB, or circulatory arrest. Total extracorporeal circulation may be performed with the ECLS circuit, or the patient may be transferred to a conventional CPB circuit during the procedure. If required, post surgical ECLS can be facilitated through prior cannulation. We have found pre-operative institution of ECLS, in the neonate with severe congenital cardiac defects, provides immediate control of hemodynamic and respiratory problems, lowers the risk of cardiac catheterization, and reduces the usage of blood products during surgery.