The Association of Oxygen Delivery and Transfusion on Cardiopulmonary Bypass with Acute Kidney Injury.

OBJECTIVES: To estimate whether the association of transfusion and acute kidney injury (AKI) has a threshold of oxygen delivery below which transfusion is beneficial but above which it is harmful. DESIGN: Retrospective study SETTING: Cardiovascular operating room and intensive care unit PARTICIPANTS: Patients undergoing cardiac surgery with continuous oxygen delivery monitoring during cardiopulmonary bypass INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Logistic regression was used to estimate the associations between oxygen delivery (mean, cumulative deficit, and bands of oxygen delivery), transfusion, and their interaction and AKI. A subgroup analysis of transfused and nontransfused patients with exact matching on cumulative oxygen deficit and time on bypass with adjustment for propensity to receive a transfusion using logistic regression. Nine hundred ninety-one of 4,203 patients developed AKI within 7 days. After adjustment for confounders, lower mean oxygen delivery (odds ratio [OR], 0.968; 95% confidence interval [CI], 0.949-0.988; p = 0.002) and transfusions (OR, 1.442; 95% CI, 1.077, 1.932; p = 0.014) were associated with increased odds of AKI by 7 days. As oxygen delivery decreased, the risk of AKI increased, with the slope of the OR steeper at <160 mL/m2/min. In the subgroup analysis, matched transfused patients were more likely than matched nontransfused patients to develop AKI (45% [n = 145] v 31% [n = 101]; p < 0.001). However, after propensity score adjustment, the difference was nonsignificant (OR, 1.181; 95% CI, 0.796-1.752; p = 0.406). CONCLUSIONS: We found a nonlinear relationship between oxygen delivery and AKI. We found no level of oxygen delivery at which transfusion was associated with a decreased risk of AKI.

Invited commentary: Total anomalous pulmonary venous connection remains a challenging pediatric disease.

Cervantes-Salazar and colleagues report the long-term surgical outcomes of 414 patients with total anomalous pulmonary venous connection (TAPVC) from January 2003 to June 2019. With an overall survival rate of 87.2% from 2003 to 2019, the authors found that an increased mortality risk was associated with infracardiac TAPVC, pulmonary venous obstruction, and postoperative mechanical ventilation. Their comprehensive study with a large sample size of varying age groups, and patients with late referrals for surgery, provide valuable insight into TAPVC surgical outcomes. Improved survival for these patients continues to be a major goal of clinical teams striving to transform treatment paradigms. The promising result of the study reported by Cervantes-Salazar and colleagues gives our field hope for a better future for these patients.

Gastrostomy Tube for Nutrition and Malignant Bowel Obstruction in Patients With Cancer.

BACKGROUND: Gastrostomy tubes (G-tubes) are invaluable clinical tools that play a role in palliation and nutrition in patients with cancer. This study aimed to better understand the risks and benefits associated with the placement and maintenance of G-tubes. METHODS: Patients who underwent placement of a G-tube for cancer from January 2013 through December 2017 at a tertiary care center were considered for inclusion. Clinical data were retrospectively collected from medical records. RESULTS: A total of 242 patients with cancer, whose average age at diagnosis was 61 years (range, 21-94 years), underwent G-tube placement for nutrition (76.4%), decompression (22.7%), or both (0.8%). Successful insertion was achieved in 96.8%, but 8 patients required >1 attempted method of insertion. In the decompression group, minor postplacement complications were less common (23.6% vs 53.5%; P<.001) and survival was shorter (P<.001) compared with the nutrition group. For those with decompressive G-tubes, 45.5% had a palliative care consult; 56.4% were seen by social workers; and 46.3% went to hospice. The frequency of hospice discharge was higher in patients who had consults (53.7% vs 23.1%; P=.01). CONCLUSIONS: Half of the patients who received decompressive G-tubes presented with stage IV disease and died within 1 month of placement. Those with >1 consult were more likely to be discharged to hospice. Patients with G-tubes for nutrition saw no change in functionality, complication rate, or survival, regardless of adjunct chemotherapy status. These findings illustrate the need for a tool to allow a better multidisciplinary approach and interventional decision-making for patients with cancer.

Efficient approach to superior vena cava baffle stenosis following the Mustard procedure: Expanding the role of a mechanical rotating dilator sheath for lead extraction.

INTRODUCTION: In adult congenital patients with transposition of the great arteries originally treated with the Mustard (atrial switch) procedure, the most common reason for re-intervention is baffle stenosis. This may be exacerbated by permanent transvenous pacemaker lead placement across the baffle. CASE REPORT: A 47-year-old female status post Mustard procedure performed at 15 months old presented with a high-grade stenosis of the superior vena cava (SVC) baffle from the SVC to the left atrium, with a nonfunctional permanent pacemaker lead passing through the baffle. A mechanical rotating dilator sheath was used for attempted lead extraction, relieving the baffle stenosis almost completely as a secondary effect, before the placement of a 10 × 27 mm Visipro balloon-expandable stent in the SVC baffle. CONCLUSIONS: Use of the mechanical rotating dilator sheath is an evolving treatment strategy in adult congenital heart disease to minimize the risk of bleeding, trauma to surrounding structures, and death. Its ability to fully alleviate baffle stenosis even when full lead extraction is not feasible or is associated with significant procedural risk, further demonstrates its expanded role in this patient population. A multidisciplinary approach and great diligence must be employed to avoid potential complications.

Left innominate vein creation using left internal jugular vein tunneled to right internal jugular vein.

BACKGROUND: Left innominate vein occlusion is a known complication of pacemaker and central venous catheter placement. For dialysis-dependent patients with an arteriovenous fistula (AVF), this can prevent successful hemodialysis and may require surgical intervention. CASE REPORT: An 8-month-old male was diagnosed with hemolytic uremic syndrome and became dialysis-dependent at 11 months of age. After multiple vascular access and peritoneal dialysis complications, the patient had construction of a brachiobasalic AVF in his left arm at 13 years old. While waiting for the AVF to mature, an attempt to remove a previously placed left subclavian vein port-a-cath was unsuccessful and a follow-up imaging revealed that the vessel had become occluded. The fistula remained patent, but due to arm swelling and venous obstruction, his fistula was not accessible. Multiple attempts to percutaneously cross the left innominate vein were unsuccessful and the patient was referred for surgical intervention. At 15 years old, the patient was taken to the operating room for transposition of the left internal jugular vein (LIJ) to the right internal jugular vein (RIJ). The LIJ was transected under the mandible and anastomosed to the RIJ. Subsequently the patient underwent VWING insertion rather than venous transposition for constant site dialysis. Although he has required frequent transcatheter dilation of the LIJ-RIJ anastomosis, the patient was successfully dialyzed using this fistula for 5 years. The patient received a cadaveric renal transplant at 5 years 20 days. CONCLUSIONS: In cases of left innominate vein stenosis, transposing the LIJ can create a new left innominate vein that can alleviate venous hypertension and preserve fistula function. This procedure avoids sternotomy and only requires one anastomosis.

Impact of Frailty in Patients Undergoing Minimally Invasive Mitral Valve Surgery.

OBJECTIVE: Psoas muscle size is a reliable marker of sarcopenia and frailty that correlates with adverse outcomes after cardiac surgery. However, its use in mitral and minimally invasive cardiac surgery is lacking. We sought to determine whether frailty, as measured by psoas muscle index, increases surgical risk for minimally invasive mitral valve surgery. METHODS: Patients undergoing isolated minimally invasive mitral surgery via right minithoracotomy were identified. Patients who underwent maze, tricuspid intervention, and those who were emergent were excluded. Total psoas muscle area was calculated using the average cross-sectional area at the L3 vertebra on computed tomography scan and indexed to body surface area. Sarcopenia was defined as <25th gender-specific percentile. Patients were stratified by sarcopenia status and outcomes compared. RESULTS: Of 287 total patients, 192 patients met inclusion criteria. Sarcopenic patients were 6 years older (66 vs 60 years, P = 0.01), had lower preoperative albumin levels (4.0 vs 4.3 g/dL, P < 0.001), and had higher Society of Thoracic Surgeons risk of morbidity/mortality (13.1% vs 9.0%, P = 0.003). Operative major morbidity or mortality was 6.4% versus 5.5% (P = 0.824), while the 1-year mortality rate was 2.1% versus 0% (P = 0.08). After risk adjustment, psoas index did not predict operative morbidity or mortality. However, sarcopenia was associated with higher odds of readmission (odds ratio = 0.74, P = 0.02). CONCLUSIONS: Contrary to other cardiac operations, for patients undergoing isolated minimally invasive mitral valve surgery, sarcopenia was not associated with increased perioperative risk except for higher readmission rates. Minimally invasive surgical approaches should be strongly considered as the approach of choice in frail patients.

Oxygen Delivery Thresholds During Cardiopulmonary Bypass and Risk for Acute Kidney Injury.

BACKGROUND: Postoperative acute kidney injury (AKI) in cardiac surgery patients is multifactorial and associated with low oxygen delivery (DO2) during cardiopulmonary bypass. METHODS: Cardiac surgical patients undergoing full cardiopulmonary bypass between May 1, 2016 and December 31, 2021 were included, whereas those on preoperative dialysis, undergoing circulatory arrest procedures, or lacking minute-to-minute physiologic data were excluded. A 5-minute running average of indexed DO2 (DO2i, mL/min/m2) was calculated ([pump flow] × [hemoglobin] × 1.36 [hemoglobin saturation] + 0.003 [arterial oxygen tension]/body surface area). AKI was defined using established Kidney Disease: Improving Global Outcomes criteria. The threshold of nadir DO2i on the effect of AKI was estimated using risk-adjusted Constrained Broken-Stick models. RESULTS: Postoperative AKI occurred among 1155 patients (29.4%), with 276 (7.0%) having stage 2 to 3 AKI. The median nadir DO2i was lower for those with (vs without) AKI (197.9 mL/min/m2 [interquartile range {IQR}, 166.3-233.2] vs 217.2 mL/min/m2 [IQR, 184.5-252.2], P < .001) and stage 2 to 3 AKI relative to stage 1 or none (186.9 mL/min/m2 [IQR, 160.1-220.5] vs 213.8 mL/min/m2 [IQR, 180.4-249.4]). In risk-adjusted analyses the estimated threshold for nadir DO2i was 231.2 mL/min/m2 (95% CI, 173.6-288.8) for any AKI and 103.3 (95% CI, 68.4-138.3) for stage 2 to 3 AKI. CONCLUSIONS: Decreasing nadir DO2i was associated with an increased risk of AKI. The identified nadir DO2i thresholds suggest management and treatment of nadir DO2i during cardiopulmonary bypass may decrease a patient's postoperative AKI risk.

Outcomes of cardiac surgical procedures performed by trainees versus consultants: A systematic review with meta-analysis.

OBJECTIVES: Cardiac surgery is highly demanding and the ideal teaching method to reach competency is widely debated. Some studies have shown that surgical trainees can safely perform full operations with equivocal outcomes compared with their consultant colleagues while under supervision. We aimed to compare outcomes after cardiac surgery with supervised trainee involvement versus consultant-led procedures. METHODS: We systematically reviewed databases (PubMed/MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Google Scholar) and reference lists of relevant articles for studies that compared outcomes of cardiac surgery performed by trainees versus consultants. Primary end points included: operative mortality, coronary events, neurological/renal complications, reoperation, permanent pacemaker implantation, and sternal complications. Secondary outcomes included cardiopulmonary bypass and aortic cross-clamp times and intensive care/in-hospital length of stay. Random effects meta-analysis was performed. RESULTS: Thirty-three observational studies that reported on a total of 81,616 patients (trainee: 20,154; consultant: 61,462) were included. There was a difference favoring trainees in terms of operative mortality in the main analysis and in an analysis restricted to propensity score-matched samples, whereas other outcomes were not consistently different in both analyses. Overall cardiopulmonary bypass and aortic cross-clamp times were longer in the trainee group but did not translate in longer intensive care unit or hospital stay. CONCLUSIONS: In the right conditions, good outcomes are possible in cardiac surgery with trainee involvement. Carefully designed training programs ensuring graduated hands-on operative exposure as primary operator with appropriate supervision is fundamental to maintain high-quality training in the development of excellent cardiac surgeons.

Academic Rank and Productivity Among United States Cardiothoracic Surgeons.

BACKGROUND: Despite a significant growth of women trainees in cardiothoracic surgery recently, women remain a minority of cardiothoracic surgeons and hold a minority of leadership positions. This study evaluates differences in cardiothoracic surgeon subspecialty choices, academic rank, and academic productivity between men and women. METHODS: The Accreditation Council for Graduate Medical Education database was used to identify 78 cardiothoracic surgery academic programs in the United States, including integrated, 4+3, and traditional fellowships, as of June 2020. A total of 1179 faculty members were identified within these programs, 585 adult cardiac surgeons (50%), 386 thoracic surgeons (33%), and 168 congenital surgeons (14%), and other, 40 (3%). Data were collected using institutional websites, ctsnet.org, doximity.com, linkedin.com, and Scopus. RESULTS: Of the 1179 surgeons, only 9.6% were women. Overall, women composed 6.7% of adult cardiac, 15% of thoracic, and 7.7% of congenital surgeons. Among subspecialties, women represent 4.5% (17 of 376) of full professors and 5% (11 of 195) of division chiefs in cardiothoracic surgery in the United States, have shorter career durations, and lower h-indices compared with men. However, women had similar m-indices, which factors in career length, compared with men in adult cardiac (0.63 vs 0.73), thoracic (0.77 vs 0.90), and congenital (0.67 vs 0.78) surgeons. CONCLUSIONS: Career duration, including cumulative research productivity, appears to be the most important factors predicting full professor rank, potentially contributing to persistent sex-based disparities in academic cardiothoracic surgery.

The Philadelphia surgery conference: a value analysis of a hands-on surgical skill-building event.

Context: Limited opportunities exist to practice technical skills and to be exposed to various surgical specialties during preclinical medical education. Objectives: To assess the value of workshop-based educational opportunities to medical students during preclinical training. Methods: One hundred and 75 medical and physician assistant students from 10 medical schools attended the 2019 Philadelphia Surgery Conference. All students received STOP THE BLEED® bleeding control training and participated in four workshops, chosen from a list of 23, that demonstrated a variety of surgical skills. Data collection was accomplished using both a pre- and postconference survey to assess changes in confidence of personal capabilities, knowledge base, and opinions regarding preclinical medical training. Results: Preconference survey results indicated low baseline confidence in personal surgical skills (mean [SD], 1.9 [1.0], on a Likert scale of 1-5), and knowledge of various surgical specialties (2.7 [1.0]). Students highly valued skill-building experiences (mean [SD], 4.2 [1.1]) and face-to-face interactions with resident and attending physicians (4.4 [0.9]). Postconference survey analysis demonstrated increased confidence in surgical ability by 52.6% (mean [SD], 2.9 [1.0]; p<0.001) and knowledge base by 34.6% (3.5 [0.8]; p<0.001). Value scores increased for both preclinical surgical skill-building opportunities (mean [SD], 4.4 [0.9]; p=0.014) and interactions with resident and attending physicians (4.7 [0.6]; p=0.002). Conclusions: The Philadelphia Surgery Conference provided a highly valuable experience to participating students, increasing confidence in personal knowledge base and surgical skills while facilitating a collaboration between students and resident and attending physicians from various surgical specialties.

Giant coronary artery aneurysm in infantile Kawasaki disease: When to use cardiac computed tomography angiography.

Transthoracic echocardiography is the imaging modality of choice for the detection of coronary artery aneurysms (CAAs) in Kawasaki disease. However, cardiac computed tomography angiography is useful in the diagnosis of distal CAAs.

Clinical Exposure to Cardiothoracic Surgery for Medical Students and General Surgery Residents.

BACKGROUND: The introduction of integrated 6-year cardiothoracic surgery (CTS) residency programs has shifted recruitment efforts to encompass not only general surgery (GS) residents, but also medical students. OBJECTIVE: The aim of this paper is to assess medical student and GS resident clinical exposure to CTS. DESIGN: Data from the Association of American Medical Colleges Visiting Student Application Service and the Accreditation Council for Graduate Medical Education Case Log Reports were collected from 2010 to 2017 and 2010 to 2018, respectively. The data extracted included medical students who applied and received an offer for elective rotations and the cases performed as a GS resident. RESULTS: A mean of 95 ± 28.5 medical students applied for CTS rotations annually and the applicants for CTS rotations increased by an average of 11.8% per year. However, significantly less students received an offer compared to other specialties (53.4% CTS vs 74.1% GS, 79.3% plastic surgery, 86.3% urology, 85.7% otolaryngology, 88.6% neurological surgery, and 89.6% orthopedic surgery) (p < 0.001). GS residents performed a mean of 39.3 ± 0.8 CTS procedures during residency: 32.9 ± 1.0 performed as a junior resident and 6.3 ± 0.7 as a chief resident. Out of all CTS procedures, 7.3% were cardiac procedures, with rates increasing from 5.6% to 8.4% during the study period (p = 0.001). CONCLUSIONS: Elective rotation opportunities in CTS are high in demand for medical students while GS residents receive limited CTS exposure, especially cardiac cases. Increasing clinical opportunities in both groups will aid in recruiting young talent to the field.

Adult congenital pulmonary valve insertion using a new bioprosthetic aortic valve: Inspiris.

We describe successful placement of the Inspiris Resilia aortic valve in the pulmonary position. This valve has advantages for immediate benefit and future percutaneous interventions, making it a promising prosthesis for adult congenital patients.

72-Hour in vivo evaluation of nitric oxide generating artificial lung gas exchange fibers in sheep.

The large, densely packed artificial surface area of artificial lungs results in rapid clotting and device failure. Surface generated nitric oxide (NO) can be used to reduce platelet activation and coagulation on gas exchange fibers, while not inducing patient bleeding due to its short half-life in blood. To generate NO, artificial lungs can be manufactured with PDMS hollow fibers embedded with copper nanoparticles (Cu NP) and supplied with an infusion of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP). The SNAP reacts with Cu NP to generate NO. This study investigates clot formation and gas exchange performance of artificial lungs with either NO-generating Cu-PDMS or standard polymethylpentene (PMP) fibers. One miniature artificial lung (MAL) made with 10 wt% Cu-PDMS hollow fibers and one PMP control MAL were attached to sheep in parallel in a veno-venous extracorporeal membrane oxygenation circuit (n = 8). Blood flow through each device was set at 300 mL/min, and each device received a SNAP infusion of 0.12 µmol/min. The ACT was between 110 and 180 s in all cases. Blood flow resistance was calculated as a measure of clot formation on the fiber bundle. Gas exchange experiments comparing the two groups were conducted every 24 h at blood flow rates of 300 and 600 mL/min. Devices were removed once the resistance reached 3x baseline (failure) or following 72 h. All devices were imaged using scanning electron microscopy (SEM) at the inlet, outlet, and middle of the fiber bundle. The Cu-PDMS NO generating MALs had a significantly smaller increase in resistance compared to the control devices. Resistance rose from 26 ±â€¯8 and 23 ±â€¯5 in the control and Cu-PDMS devices, respectively, to 35 ±â€¯8 mmHg/(mL/min) and 72 ±â€¯23 mmHg/(mL/min) at the end of each experiment. The resistance and SEM imaging of fiber surfaces demonstrate lower clot formation on Cu-PDMS fibers. Although not statistically significant, oxygen transfer for the Cu-PDMS MALs was 13.3% less than the control at 600 mL/min blood flow rate. Future in vivo studies with larger Cu-PDMS devices are needed to define gas exchange capabilities and anticoagulant activity over a long-term study at clinically relevant ACTs. STATEMENT OF SIGNIFICANCE: In artificial lungs, the large, densely-packed blood contacting surface area of the hollow fiber bundle is critical for gas exchange but also creates rapid, surface-generated clot requiring significant anticoagulation. Monitoring of anticoagulation, thrombosis, and resultant complications has kept permanent respiratory support from becoming a clinical reality. In this study, we use a hollow fiber material that generates nitric oxide (NO) to prevent platelet activation at the blood contacting surface. This material is tested in vivo in a miniature artificial lung and compared against the clinical standard. Results indicated significantly reduced clot formation. Surface-focused anticoagulation like this should reduce complication rates and allow for permanent respiratory support by extending the functional lifespan of artificial lungs and can further be applied to other medical devices.

Zwitterionic poly-carboxybetaine coating reduces artificial lung thrombosis in sheep and rabbits.

Current artificial lungs fail in 1-4 weeks due to surface-induced thrombosis. Biomaterial coatings may be applied to anticoagulate artificial surfaces, but none have shown marked long-term effectiveness. Poly-carboxybetaine (pCB) coatings have shown promising results in reducing protein and platelet-fouling in vitro. However, in vivo hemocompatibility remains to be investigated. Thus, three different pCB-grafting approaches to artificial lung surfaces were first investigated: 1) graft-to approach using 3,4-dihydroxyphenylalanine (DOPA) conjugated with pCB (DOPA-pCB); 2) graft-from approach using the Activators ReGenerated by Electron Transfer method of atom transfer radical polymerization (ARGET-ATRP); and 3) graft-to approach using pCB randomly copolymerized with hydrophobic moieties. One device coated with each of these methods and one uncoated device were attached in parallel within a veno-venous sheep extracorporeal circuit with no continuous anticoagulation (N = 5 circuits). The DOPA-pCB approach showed the least increase in blood flow resistance and the lowest incidence of device failure over 36-hours. Next, we further investigated the impact of tip-to-tip DOPA-pCB coating in a 4-hour rabbit study with veno-venous micro-artificial lung circuit at a higher activated clotting time of 220-300 s (N ≥ 5). Here, DOPA-pCB reduced fibrin formation (p = 0.06) and gross thrombus formation by 59% (p < 0.05). Therefore, DOPA-pCB is a promising material for improving the anticoagulation of artificial lungs. STATEMENT OF SIGNIFICANCE: Chronic lung diseases lead to 168,000 deaths each year in America, but only 2300 lung transplantations happen each year. Hollow fiber membrane oxygenators are clinically used as artificial lungs to provide respiratory support for patients, but their long-term viability is hindered by surface-induced clot formation that leads to premature device failure. Among different coatings investigated for blood-contacting applications, poly-carboxybetaine (pCB) coatings have shown remarkable reduction in protein adsorption in vitro. However, their efficacy in vivo remains unclear. This is the first work that investigates various pCB-coating methods on artificial lung surfaces and their biocompatibility in sheep and rabbit studies. This work highlights the promise of applying pCB coatings on artificial lungs to extend its durability and enable long-term respiratory support for lung disease patients.