Zachary N. Kon

Ambulatory veno-venous extracorporeal membrane oxygenation: Innovation and pitfalls

OBJECTIVE End-stage lung disease and severe acute lung injury are complex entities that remain challenges to manage. Therapies include early institution of mechanical ventilation with positive end-expiratory pressure, permissive hypercapnia, pulmonary vasodilators, and complex fluid regimens. Veno-venous extracorporeal membrane oxygenation is an available treatment option for these patients but, in its conventional form, can be associated with significant complications. We present our early experience with an attempt to optimize extracorporeal membrane oxygenation, emphasizing reduced adjunctive mechanical ventilatory support and aggressive rehabilitation, with a goal of ambulation. This strategy has been enabled by the introduction of a dual-lumen draw and return cannula placed via the internal jugular vein. METHODS The first 10 patients (mean age of 45.3 years, 8 male) treated with this strategy between January 1, 2009, and October 1, 2009, were retrospectively reviewed. The ambulatory extracorporeal membrane oxygenation strategy was initiated with an aim of minimal mechanical ventilation and aggressive rehabilitation. The patients were intended to be weaned from all respiratory support or bridged to transplantation. RESULTS The mean duration of extracorporeal membrane oxygenation was 20 (9-59) days, with average mean blood flows of 3.5 (1.6-4.9) L/min, and levels of CO(2) removal and O(2) transfer of 228 (54-570) mL/min and 127 (36-529) mL/min, respectively. Six of 10 patients were weaned from respiratory support (N = 4) or underwent transplantation (N = 2) and survived to discharge from the hospital. The remaining 4 patients died of sepsis (N = 3) and withdrawal of care after renal failure (N = 1). Four of the 6 surviving patients were extubated and ambulatory while still on extracorporeal membrane oxygenation. During that time, 3 of the 4 patients exercised at the bedside, with the remaining patient able to undergo full cardiopulmonary rehabilitation, including treadmill walking. CONCLUSIONS Improvements in the durability of membrane blood oxygenators and pumps have prompted renewed consideration of extracorporeal membrane oxygenation in patients with severe lung disease. This report describes an attempt to augment extracorporeal membrane oxygenation with the goal of ambulation by minimizing mechanical ventilatory support and using aggressive in-and-out-of-bed rehabilitation.

Hybrid coronary revascularization using robotic totally endoscopic surgery: perioperative outcomes and 5-year results.

BACKGROUND Hybrid coronary revascularization combines minimally invasive coronary artery bypass grafting and catheter-based interventions. This treatment option represents a viable alternative to both open multivessel coronary bypass surgery through sternotomy and multivessel percutaneous coronary intervention. The surgical component of hybrid coronary intervention can be offered in a completely endoscopic fashion using robotic technology. We report on one of the largest series to date. METHODS From 2001 to 2011, 226 patients (age, 61 years [range, 31 to 90 years]; 77.0% male; EuroSCORE, 2 [range, 0 to 13]) underwent hybrid coronary interventions on an intention-to-treat basis. Robotically assisted procedures were performed using the daVinci, daVinci S, and daVinci Si surgical telemanipulation systems (Intuitive Surgical, Inc, Sunnyvale, CA) and included 147 single, 72 double, and 7 triple endoscopic coronary artery bypass grafting procedures. Surgery was carried out first in 160 cases (70.8%), percutaneous coronary intervention was carried out first in 38 cases (16.8%), and 28 patients underwent simultaneous operations in a hybrid operating room (12.4%). Drug-eluting stents were used in 70.0% of the patients. RESULTS Hospital mortality was 3 of 226 patients (1.3%), and hospital stay averaged 6 days (range, 3 to 54 days). Patients walked outside 7 days (range, 3 to 97 days) postoperatively and performed general household work 14 days (range, 7 to 180 days) postoperatively. Full activity was resumed at 42 days (range, 7 to 720 days). Five-year survival was 92.9%, and 5-year freedom from major adverse cardiac and cerebral events was 75.2%. At 5 years, 2.7% of bypass grafts and 14.2% of percutaneous coronary intervention targets needed reintervention. CONCLUSIONS Robotically assisted hybrid coronary intervention enables surgical treatment of multivessel coronary artery disease with minimal trauma. Perioperative results and intermediate-term outcomes meet the standards of open coronary artery bypass grafting. Recovery time is short, and reintervention rates are acceptable.

The use of lung donors older than 55 years: a review of the United Network of Organ Sharing database.

BACKGROUND Current lung transplantation guidelines stipulate that the ideal donor is aged younger than 55 years, but several institutions have reported that outcomes using donors aged 55 years and older are comparable with those of younger donors. METHODS We retrospectively reviewed the United Network for Organ Sharing (UNOS) database to identify all adult lung transplants between 2000 and 2010 in the United States. Patients were stratified by donor age 18 to 34 (reference), 35 to 54, 55 to 64, and ≥ 65 years. Primary outcomes included survival at 30 days and at 1, 3, and 5 years and rates of bronchiolitis obliterans syndrome (BOS). Survival was assessed using the Kaplan-Meier method. Risk factors for mortality were identified by multivariable Cox and logistic regression. RESULTS We identified 10,666 recipients with median follow-up of 3 years (range, 0-10 years). Older donors were more likely to have died of cardiovascular or cerebrovascular causes, but there were no differences in recipient diagnosis, lung allocation score, or incidence of BOS as a function of donor age. The use of donors aged 55 to 64 years was not a risk factor for mortality at 1 year (odds ratio, 1.1; p = 0.304) or 3 years (odds ratio, 0.923; p = 0.571) compared with the reference group; however, use of donors aged > 65 years was associated with increased mortality at both time points (odds ratio, 2.8 and 2.4, p < 0.02). CONCLUSIONS Outcomes after lung transplantation using donors aged 55 to 64 years were similar to those observed with donors meeting conventional age criteria. Donors aged ≥ 65 years, however, were associated with decreased intermediate-term survival, although there was no increased risk of BOS for this group.

Class III Obesity is Not a Contraindication to Venovenous Extracorporeal Membrane Oxygenation Support

BACKGROUND The use of venovenous extracorporeal membrane oxygenation (ECMO) has increased as a bridge to recovery for acute respiratory distress syndrome (ARDS) refractory to conventional support. Morbid obesity can pose a significant challenge to obtaining indexed flows, and outcomes in this population are not well described. METHODS Patients requiring ECMO for ARDS between January 2009 and November 2012 were retrospectively reviewed. Demographics, ECMO variables, and outcomes were assessed. Morbid obesity and super obesity were defined as a body mass index (BMI) greater than 40 kg/m(2) and greater than 50 kg/m(2), respectively. RESULTS Fifty-five patients with ARDS were placed on ECMO during the study period. Twelve were morbidly obese with a BMI of 49.0 kg/m(2) (interquartile range [IQR]: 45.4-57.3 kg/m(2)). Pre-ECMO mechanical ventilatory support and indices of disease severity were similar between the 2 groups, as were cannulation strategy and duration of ECMO support. Nine (75%) morbidly obese patients and 27 (63%) non-morbidly obese patients were successfully weaned from ECMO support, and patient survival to time of discharge was 67% and 58%, respectively. In the subset of super obese patients (n = 6; BMI, 57.3 kg/m(2) [IQR: 51.3-66.5 kg/m(2)]), recovery and midterm survival was 100%. CONCLUSIONS In this review, class III obesity was not associated with poorer outcomes, and based on these data, ECMO support should not be withheld from this patient population.

Optical Coherence Tomography Imaging as a Quality Assurance Tool for Evaluating Endoscopic Harvest of the Radial Artery

BACKGROUND Concerns about intimal disruption and spasm have limited enthusiasm for endoscopic radial artery harvest (ERAH), although the risk of these problems after this procedure remains uncertain. Radial artery conduits were screened intraoperatively before and after ERAH vs open harvest using catheter-based high-resolution optical coherence tomography (OCT) imaging. METHODS Twenty-four cadavers and 60 coronary artery bypass graft (CABG) patients scheduled to receive a RA graft underwent OCT imaging before (in situ) and after (ex vivo) open harvest or ERAH. Spasm was quantified by the percentage change in luminal volume between images. Intimal disruption was classified as minor or severe depending on whether the defect was confined to branch ostia or involved the luminal surface. Histology was used to confirm OCT findings. RESULTS Luminal volume significantly declined after harvest in all RAs from CABG patients, but there was no difference between groups: -43% +/- 29% vs -35% +/- 38% change after ERAH (n = 21) vs open harvest (n = 39; p = 0.342). Significantly more intimal injury was noted after ERAH vs open harvest (34/41 vs 9/43, intimal tears/total evaluated RAs, p < 0.0001). Most intimal injury was minor: only 2 tears involved the luminal surface of the RA (both after ERAH). Serial imaging in cadavers revealed that 86% of ostial tears occur in ERAH during the initial blunt dissection step using the endoscope. CONCLUSIONS Although branch injury is a pitfall of ERAH, OCT imaging documented that the quality of RA procured is acceptable and comparable with open harvest. Catheter-based OCT provides an important quality assurance tool for RA harvest.

Thinking inside the graft: applications of optical coherence tomography in coronary artery bypass grafting

Recent advances in catheter-based optical coherence tomography (OCT) have provided the necessary resolution and acquisition speed for high-quality intravascular imaging. Complications associated with clearing blood from the vessel of a living patient have prevented its wider acceptance. We identify a surgical application that takes advantage of the vascular imaging powers of OCT but that circumvents the difficulties. Coronary artery bypass grafting (CABG) is the most commonly performed major surgery in America. A critical determinant of its outcome has been postulated to be injury to the conduit vessel incurred during the harvesting procedure or pathology preexistent in the harvested vessel. As a test of feasibility, intravascular OCT imaging is obtained from the radial arteries (RAs) and/or saphenous veins (SVs) of 35 patients scheduled for CABG. Pathologies detected by OCT are compared to registered histological sections obtained from discarded segments of each graft. OCT reliably detects atherosclerotic lesions in the RAs and discerns plaque morphology as fibrous, fibrocalcific, or fibroatheromatous. OCT is also used to assess intimal trauma and residual thrombi related to endoscopic harvest and the quality of the distal anastomosis. We demonstrate the feasibility of OCT imaging as an intraoperative tool to select conduit vessels for CABG.

Harmonic scalpel versus electrocautery for harvest of radial artery conduits: Reduced risk of spasm and intimal injury on optical coherence tomography

OBJECTIVE Vasospasm is the primary obstacle to widespread adoption of the radial artery as a conduit in coronary artery bypass grafting. We used optical coherence tomography, a catheter-based intravascular imaging modality, to measure the degree of radial artery spasm induced by means of harvest with electrocautery or a harmonic scalpel in patients undergoing coronary artery bypass grafting. METHODS Radial arteries were harvested from 44 consecutive patients with a harmonic scalpel (n = 15) or electrocautery (n = 29). Vessels were imaged before harvesting and after removal from the arm, with saphenous vein tracts serving as internal controls. Optical coherence tomographic findings for the degree of harvesting-induced injury were validated against histologic measures. RESULTS Optical coherence tomographic measures of endovascular dimensions and injury correlated strongly with histologic findings. Mean luminal volume, a measure of vasospasm, decreased significantly less after harvesting with a harmonic scalpel (9% +/- 7%) than with electrocautery (35% +/- 6%, P = .015). Completely intact intima was present in 11 (73%) of 15 radial arteries harvested with a harmonic scalpel (73%) compared with 9 of 29 arteries harvested by means of electrocautery (31%, P = .011). Intraoperative flow measurements and patency rates at 5 days postoperatively were not significantly different among groups. CONCLUSIONS Optical coherence tomography provides a level of speed and accuracy for quantifying endothelial injury and vasospasm that has not been described for any other modality, suggesting potential as an intraoperative quality assurance tool. Our optical coherence tomographic findings suggest that the harmonic scalpel induces less spasm and intimal injury compared with electrocautery.

Venovenous Extracorporeal Membrane Oxygenation as a Bridge to Lung Transplantation: Successful Transplantation After 155 Days of Support

We present a case of a woman with acute respiratory distress syndrome and irrecoverable lung function that was successfully bridged to lung transplantation after 155 consecutive days of venovenous extracorporeal membrane oxygenation.

Current state of ex-vivo lung perfusion

Purpose of reviewThe purpose of the current report is to review the ex-vivo peer-reviewed literature published in the last 5 years and to summarize the findings. Recent findingsEncouraging data have been published by several centers utilizing ex-vivo lung perfusion (EVLP) as a means to identify viable grafts from the high-risk donor pool. The outcomes of transplanted lungs that were initially declined because of poor quality, but reevaluated with ex-vivo perfusion, are equivalent to standard criteria donor lungs. Further, research reports have emphasized the role of ex-vivo perfusion as a platform to improve graft quality and reduce the injurious effects of ischemia-reperfusion. SummaryOver the last 10 years, EVLP has proved its value as a reassessment tool to increase donor utilization. As short- and long-term data demonstrate the safety of EVLP, its use as a therapeutic platform is emerging, along with the promise of a new era in lung transplantation.

Outcomes after surgical pulmonary embolectomy for acute submassive and massive pulmonary embolism: A single-center experience

Objectives: Ideal treatment strategies for submassive and massive pulmonary embolism remain unclear. Recent reports of surgical pulmonary embolectomy have demonstrated improved outcomes, but surgical technique and postoperative outcomes continue to be refined. The aim of this study is to describe in‐hospital survival and right ventricular function after surgical pulmonary embolectomy for submassive and massive pulmonary embolism with excessive predicted mortality (≥5%). Methods: All patients undergoing surgical pulmonary embolectomy (2011‐2015) were retrospectively reviewed. Patients with pulmonary embolism were stratified as submassive, massive without arrest, and massive with arrest. Submassive was defined as normotensive with right ventricular dysfunction. Massive was defined as prolonged hypotension due to the pulmonary embolism. Preoperative demographics, intraoperative variables, and postoperative outcomes were compared. Results: A total of 55 patients were identified: 28 as submassive, 18 as massive without arrest, and 9 as massive with arrest. All patients had a right ventricle/left ventricle ratio greater than 1.0. Right ventricular dysfunction decreased from moderate preoperatively to none before discharge (P < .001). In‐hospital and 1‐year survival were 93% and 91%, respectively, with 100% survival in the submassive group. No patients developed renal failure requiring hemodialysis at discharge or had a postoperative stroke. Conclusions: In this single institution experience, surgical pulmonary embolectomy is a safe and effective therapy to treat patients with a submassive or massive pulmonary embolism. Although survival in this study is higher than previously reported for patients treated with medical therapy alone, a prospective trial comparing surgical therapy with medical therapy is necessary to further elucidate the role of surgical pulmonary embolectomy in the treatment of pulmonary embolism.