ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Case Reports
From Baghdad to Germany: use of a new pumpless extracorporeal lung assist system in two severely injured US soldiers.
The authors describe a new extracorporeal pumpless interventional lung assist system (iLA) that was implemented in two US soldiers with severe acute respiratory distress syndrome received from enemy action in Iraq, who were at risk for critical hypoxemia/hypercapnia. The system is characterized by a new low-resistance gas exchange membrane that is integrated in an arterial-venous bypass established by cannulation of the femoral artery and vein. Cardiovascular stability is essential to produce sufficiently high blood flow rates over the gas exchange unit. ⋯ The iLA was removed after 15 and 8 days of continuous operation, respectively, and both soldiers were successfully weaned from mechanical ventilation. Interventional, extracorporeal pump-free pulmonary support opens up new possibilities for pulmonary protection due to ease of use, effectiveness, and low costs; however, there is concern of distal limb ischemia. Experiences to date are encouraging, although randomized studies are lacking, and the procedure carries significant risks.
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A long-term left ventricular assist system for permanent use in advanced heart failure is being developed on the basis of a compact centrifugal pump with a magnetically levitated rotor and single-fault-tolerant electronics. Key features include its "bearingless" (magnetic levitation) design, textured surfaces similar to the HeartMate XVE left ventricular assist device (LVAD) to reduce anticoagulation requirements and thromboembolism, a sensorless flow estimator, and an induced pulse mode for achieving an increased level of pulsatility with continuous flow assistance. In vitro design verification testing is underway. ⋯ Induced pulse mode demonstrated the ability to produce a physiological pulse pressure in vivo. Thirteen LVADs have achieved between 16 to 40 months of long-term in vitro reliability testing and will be continued until failure. Both percutaneous and fully implanted systems are in development, with a modular connection for upgrading without replacing the LVAD.
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Comparative Study
Carbon dioxide clearance in rabbits during expiratory phase intratracheal pulmonary ventilation.
The purpose of this study was to compare the efficacy of CO2 removal during conventional mechanical ventilation (CMV) with and without expiratory phase intratracheal pulmonary ventilation (expiratory ITPV or Exp-ITPV); and to compare CO2 clearance during Exp-ITPV, in pressure-controlled ventilation (PCV) and in volume-controlled ventilation (VCV) modes. Seven anesthetized rabbits were tracheotomized and intubated using a 4 mm endotracheal tube. Venous and arterial lines were established. ⋯ Exp-ITPV, as compared with CMV, reduced arterial PCO2 by 12% and 21% in PCV and VCV modes, respectively (p < 0.02 and p < 0.001; one-sided paired t test), without significant changes in other cardiorespiratory variables. In conclusion, Exp-ITPV is more effective than CMV in clearing CO2 through a small endotracheal tube. Exp-ITPV is also more effective in VCV mode than PCV mode.
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Comparative Study
Extracorporeal membrane oxygenation for perioperative cardiac support in children I: experience at the Deutsches Herzzentrum Berlin (1987-2005).
We report our experience in pediatric patients supported by extracorporeal membrane oxygenation (ECMO) for perioperative circulatory failure from January 1987 to June 2005. Pediatric patients (n = 110) who had ECMO support for congenital heart defects, myocarditis, and cardiomyopathy (age range, newborn to 18 years; weight range, 2.3-69 kg) were included and divided into three groups based on timing of ECMO support. EMCO support was used preoperatively in 21 patients (19.1%) (mean age, 4 years +/- 8 months; mean weight, 23.7 +/- 8.9 kg). ⋯ Mean duration of ECMO was 4.6 +/- 1 days. Mean postoperative day of ECMO institution was 40.4 +/- 2 days. Our experience shows that ECMO support can be offered perioperatively to any patient with potentially reversible pulmonary, cardiac, or cardiopulmonary failure, excluding those whose outcome is inevitable.
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Heart transplantation is indicated for children with end-stage heart failure or complex inoperable congenital defects. Due to the shortage of pediatric donor hearts, various bridge techniques have been used for pediatric recipients to prolong patient survival until a heart is available. This study evaluates long-term outcome of bridge and nonbridge support for pediatric heart transplantation. ⋯ Pediatric heart transplantation can be accomplished with excellent early survival despite multiple prior cardiac operations and relatively severe illness. For the variety in small, low-body-weight pediatric patients, mechanical circulatory support using ECMO is suitable for managing sudden collapse while waiting for heart transplantation, and graft dysfunction after cardiac transplantation. The mortality rate is acceptable in this very high-risk group of patients and long-term outcome is good.