ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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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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Extracorporeal membrane oxygenation (ECMO) is used as a salvage therapy in children with irreversible myocardial failure who may be candidates for heart transplantation (HTx) (at the Hospital for Sick Children). We retrospectively assessed outcomes of children wait-listed for HTx from ECMO, and risk factors for patients (pts) bridged to HTx from January 1990 through December 2005. Of 205 patients supported with cardiac ECMO, 46 were wait-listed for HTx. ⋯ Risk factors for early death were older age, higher body surface area, higher creatinine before and during ECMO, fungal infections, and exposure to blood products. In summary, few risk factors preclude HTx candidacy from ECMO. The impact of newer assist technology on ECMO, wait-list mortality, and HTx outcomes remains to be elucidated.
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We studied 12 consecutive neonates placed on venoarterial extracorporeal membrane oxygenation (ECMO) in 2004-2005. Activated clotting times (ACT) and anti-factor Xa levels were measured, and the corresponding heparin drip rate was noted. The mean heparin drip rate was 42.2 +/- 10.9 (SD) U/kg/hour (range 20.0-69.5 U/kg/hour). ⋯ However, there was a positive correlation (r = 0.46, p < 0.0005) between day on ECMO and anti-factor Xa activities. In these neonatal patients on venoarterial ECMO, ACT was not a reliable indicator of heparin effect. Furthermore, the increase in anti-factor Xa levels with time on ECMO suggests that heparin accumulates and/or that anti-thrombin III levels decrease with time on ECMO.
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Extracorporeal membrane oxygenation (ECMO) has become the standard technique of mechanical support for the failing circulation following repair of congenital heart lesions. The objective of this study was to identify predictors of survival in patients requiring postcardiotomy ECMO. The Aristotle score, a method developed to evaluate quality of care based on complexity, was investigated as a potential predictor of outcome. ⋯ Age, weight, and single-ventricle physiology were not significant. In a logistic regression model, an Aristotle score < 14 was identified as a predictor of survival (OR 0.12, CI 0.02-0.87). The Aristotle score is predictive of outcome in patients requiring postcardiotomy ECMO and may serve as a uniform criterion when comparing and evaluating quality of care and performance in this complex patient population.
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We examined whether hemodynamic improvement after high-flow hemofiltration predicts survival in patients treated with standard continuous renal replacement therapy (CRRT). This was a prospective, observational cohort study of 169 patients, measuring the mean arterial pressure (MAP) and norepinephrine (NE) dosage before and 24 hours after CRRT. Responders were defined as having a 20% reduction in NE dosage or a 20% rise in MAP with no increase in NE, compared with nonresponders. ⋯ In unstable patients, mortality rate was 30% in responders versus 87% in nonresponders (p < 0.001) (72% sensitivity and 86% specificity for predicting death). Logistic regression analysis showed that the only variables associated with death were APACHE II at admission (OR, 1.06; 95% CI, 1.0 to 1.12), percent creatinine decrease (OR, 0.98; CI, 0.96 to 1.0), and lack of hemodynamic response to CRRT (OR, 7.04; CI, 3.3 to 15.02). Hemodynamic improvement after 24-hour CRRT is a strong predictor of survival.