A Population Pharmacokinetic Model for Vancomycin in Adult Patients Receiving Extracorporeal Membrane Oxygenation Therapy.

The literature on the pharmacokinetics of vancomycin in patients undergoing extracorporeal membrane oxygenation (ECMO) therapy is sparse. A population pharmacokinetic (PK) model for vancomycin in ECMO patients was developed using a nonlinear mixed effects modeling on the concentration-time profiles of 14 ECMO patients who received intravenous vancomycin. Model selection was based on log-likelihood criterion, goodness of fit plots, and scientific plausibility. Identification of covariates was done using a full covariate model approach. The pharmacokinetics of vancomycin was adequately described with a two-compartment model. Parameters included clearance of 2.83 L/hr, limited central volume of distribution 24.2 L, and low residual variability 0.67%. Findings from the analysis suggest that standard dosing recommendations for vancomycin in non-ECMO patients are adequate to achieve therapeutic trough concentrations in ECMO patients. This further shows that ECMO minimally affects the PK of vancomycin in adults including in higher-weight patients.

Veno-venous extracorporeal membrane oxygenation using a double-lumen bi-caval cannula for severe respiratory failure post total artificial heart implantation.

We report a unique utilization of a double-lumen, bi-caval Avalon cannula for veno-venous (VV) extracorporeal membrane oxygenation (ECMO) during placement of a total artificial heart (TAH, SynCardia, Tucson, AZ). A 22-year-old female with post-partum cardiomyopathy was rescued on veno-arterial (VA) ECMO because of cardiogenic shock. The inability to wean ECMO necessitated implantation of the TAH as a bridge to transplant. In addition, the patient continued to have respiratory failure and concomitant VV ECMO was planned with the implant. During TAH implantation, the Avalon cannula was placed percutaneously from the right internal jugular vein into the inferior vena cava (IVC) under direct vision while the right atrium was open. During VV ECMO support, adequate flows on both ECMO and TAH were maintained without adverse events. VV ECMO was discontinued, without reopening the chest, once the patient's respiratory failure improved. However, the patient subsequently developed a profound respiratory acidosis and required VV ECMO for CO2 removal. The Avalon cannula was placed in the femoral vein to avoid accessing the internal jugular vein and risking damage to the TAH. The patient's oxygenation eventually improved and the cannula was removed at the bedside. The patient was supported for 22 days on VV ECMO and successfully weaned from the ventilator prior to her orthotropic heart transplantation.

A cost-reducing extracorporeal membrane oxygenation (ECMO) program model: a single institution experience.

BACKGROUND: The worldwide demand for ECMO support has grown. Its provision remains limited due to several factors (high cost, complicated technology, lack of expertise) that increase healthcare cost. Our goal was to assess if an intensive care unit (ICU)-run ECMO model without continuous bedside perfusionists would decrease costs while maintaining patient safety and outcomes. METHOD: A new ECMO program was implemented in 2010, consisting of dedicated ICU multidisciplinary providers (ICU-registered nurses, mid-level providers and intensivists). In year one, we introduced an education platform, new technology and dedicated space. In year two, continuous bedside monitoring by perfusionists was removed and new management algorithms designating multidisciplinary providers as first responders were established. The patient safety and cost benefit from the removal of the continuous bedside monitoring of the perfusionists of this new ECMO program was retrospectively reviewed and compared. RESULTS: During the study period, 74 patients (28 patients in year 1 and 46 patients in year 2) were placed on ECMO (mean days: 8 ± 5.7). The total annual hospital expenditure for the ECMO program was significantly reduced in the new model ($234,000 in year 2 vs. $600,264 in year 1), showing a 61% decrease in cost. This cost decrease was attributed to a decreased utilization of perfusion services and the introduction of longer lasting and more efficient ECMO technology. We did not find any significant changes in registered nurse ratios or any differences in outcomes related to ICU safety events. CONCLUSION: We demonstrated that the ICU-run ECMO model managed to lower hospital cost by reducing the cost of continuous bedside perfusion support without a change in outcomes.

Successful management of bleeding complications in patients supported with extracorporeal membrane oxygenation with primary respiratory failure.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) is a lifesaving procedure in patients with severe respiratory insufficiency failing conventional support. Bleeding complications are common due to the necessity for anticoagulation and circuit-related factors. METHODS: A retrospective review was conducted in patients requiring ECMO for respiratory failure from 7/2010 to 6/2011 to identify episodes of major bleeding, bleeding management and outcomes. RESULTS: Twenty-one patients were supported with ECMO during the study although five experienced massive bleeding related to chest tube insertion, jejunal arterio-venous malformations, distal perfusion cannula dislodgement and ventricular rupture. Patients required aggressive resuscitation or endoscopic or operative intervention, totaling 28 procedures. There were no instances of dehiscence, infection or sepsis related to interventions. Anticoagulation was stopped six hours before and restarted 24 hours after major interventions, with no thrombotic or neurologic complications. All patients weaned off ECMO were discharged. CONCLUSIONS: ECMO bleeding complications can be managed successfully via surgical and endoscopic approaches in this high-risk population.

Ischemia of the interventricular septum. A mechanism of right ventricular failure during mechanical left ventricular assist.

Right ventricular failure has been noted in up to 25% of patients requiring a left ventricular assist device. Altered septal motion or function is one proposed mechanism of right ventricular failure during left heart bypass. We studied the effect of regional ischemia and reperfusion of the interventricular septum on right ventricular function during complete left heart bypass. In six calves the septal perforating branches of the proximal left anterior descending coronary artery were isolated for intermittent occlusion. Complete left heart bypass was established with a Pierce-Donachy left ventricular assist device. Right and left ventricular function were studied with two-dimensional echocardiography and with intraventricular pressure monitors. Establishment of left heart bypass did not significantly affect right ventricular developed pressure, right ventricular end-diastolic area, or right ventricular fractional change in area. Left heart bypass significantly (p less than 0.001) decreased percent systolic septal wall thickening. Septal ischemia during left heart bypass resulted in a decrease in right ventricular developed pressure (p = 0.09), significant increase in right ventricular end-diastolic area (p = 0.002) and significant decrease in right ventricular fractional change in area (p less than 0.001), and a further decrease in interventricular septal wall thickening (p = 0.016). The interventricular septum became thin with flattening of its normal contour. Septal reperfusion resulted in right ventricular recovery with significant improvement in all factors (p less than 0.02). Similar results were documented during a second episode of septal ischemia with recovery after septal reperfusion. In some cases, septal ischemia may be an important factor in the development of right ventricular failure during left heart bypass.

Endomyocardial biopsy: variations in venous access for endomyocardial biopsy in cardiac transplantation.

With the increasing number of cardiac transplantation procedures performed worldwide, a strategy for endomyocardial biopsy techniques has evolved at our institution. Specific approaches for venous access for biopsy purposes are described. These include approaches via the right internal jugular vein, right external jugular vein, left subclavian vein, and the femoral veins. Particular emphasis is placed on the technical nuances of each approach. In approximately 2,000 endomyocardial biopsies performed on 155 transplant patients from 1984-1989, only two major complications occurred, only one of which required operative intervention. This was a perforated right ventricle, and the patient recovered after repair without further sequelae. No pneumothoraces or infection occurred during this time period. With proper understanding of regional anatomy, fluoroscopic appearance, and experience, endomyocardial biopsies can be performed with an extremely low incidence of major or minor complications.

Cognitive function in patients with symptomatic dilated cardiomyopathy before and after cardiac transplantation.

Pre- and postoperative cognitive performance of candidates for heart transplantation was examined by means of an extensive battery of neuropsychological measures. A total of 54 patients completed the preoperative cognitive protocol, 20 of whom also completed postoperative testing. Age (less than 50 or greater than or equal to 50 years of age) and the primary cause of cardiac deterioration (idiopathic, ischemic disease or rheumatic/congenital defects) were the major classification variables. The main findings of this study were: 1) Preoperative neuropsychological measures revealed a high frequency of impaired performance, particularly in measures of memory, higher level processing of information and motor speed. A pattern consistent with diffuse rather than focal or lateralized cerebral deficits was observed. Significant differences were not found on the basis of the cause of cardiac disease, but some were observed for age (the older group was more impaired). 2) A comparison of pre- and postoperative cognitive scores failed to show significant cognitive improvement despite greatly improved physical health. The cause of cardiac deterioration was not differentially associated with postoperative cognitive performance, and there was equivocal evidence for age effects. These findings may have implications for the selection of transplant recipients and the timing of transplantation surgery.

Successful heart transplantation in recipients with recent preoperative pulmonary emboli.

Acute pulmonary embolus (less than 6 weeks old) has been considered an absolute contraindication to heart transplantation for fear of the potential problems of lung abscess, empyema, bronchopleural fistula, and systemic sepsis in an immunosuppressed patient. It is difficult to adhere to this principle because 30% to 50% of patients with dilated cardiomyopathy may have an acute pulmonary embolus and would be excluded from transplantation. Several centers have considered such patients for heart transplantation if they are young, on maximal medical therapy, and in extremis. The surgical management of the postoperative pulmonary problems can include bronchoscopy, antibiotics, surgical drainage, decortication, and pulmonary resection with or without muscle flaps. We describe our approach to two such patients who were managed successfully with lobectomies and latissimus dorsi muscle flaps to seal the bronchus and fill the pleural space.

Heart/heart-lung transplantation. The domino procedure.

Orthotopic heart transplantation has become an accepted therapeutic modality limited only by availability of donor organs. Heart-lung transplantation is also being performed with increasing frequency due to improvements in distant procurement techniques. Although the majority of patients requiring heart-lung transplantation have cardiac dysfunction, there is a subset with no cardiac compromise that can serve as donors of cardiac allografts before heart-lung transplantation. We report a technique for sequential heart/heart-lung transplantation in such a subset of patients.

Sternotomy closure with Parham bands.

The closure of a median sternotomy incision requires secure bony approximation to prevent postoperative pain, sternal click, and/or nonunion of bone. The standard technique of sternotomy closure involves the use of stainless steel wires for reapproximation of the sternum. These wires occasionally break or pull through bone, resulting in instability of either a portion of the sternum or the entire sternum. Presented here is our technique for sternotomy closure that provides secure closure with reduced postoperative morbidity.

A shorter hospital stay after cardiac pacemaker implantation.

In an effort to shorten the hospital stay after implantation of a permanent cardiac pacemaker, some physicians have begun performing pacemaker implantation on an ambulatory basis. To assess the potential safety of shortening the duration of hospitalization after pacemaker implantation, we reviewed the complications that occurred in 100 consecutive patients after pacemaker implantation and noted the time after the implantation when the complications occurred. In our study group, all complications that necessitated invasive intervention occurred within 24 hours after the pacemaker implantation. Complications that necessitated noninvasive programming occurred as long as 72 hours after implantation, and all could have been safely corrected at the time of follow-up had the patient been dismissed at the 24-hour period. Although we do not believe that ambulatory pacemaker implantation should be routinely implemented at this time, the practice of dismissing patients at 24 hours after pacemaker implantation and scheduling subsequent outpatient follow-up seems to be safe and effective.