Cardiopulmonary bypass management and acute kidney injury in cardiac surgery patients.

BACKGROUND: Cardiopulmonary bypass (CPB) ensures tissue oxygenation during cardiac surgery. New technology allows continuous registration of CPB variables during the operation. The aim of the present investigation was to study the association between CPB management and the risk of postoperative acute kidney injury (AKI). METHODS: This observational study based on prospectively registered data included 2661 coronary artery bypass grafting and/or valve patients operated during 2016-2020. Individual patient characteristics and postoperative outcomes collected from the SWEDEHEART registry were merged with CPB variables automatically registered every 20 s during CPB. Associations between CPB variables and AKI were analyzed with multivariable logistic regression models adjusted for patient characteristics. RESULTS: In total, 387 patients (14.5%) developed postoperative AKI. After adjustments, longer time on CPB and aortic cross-clamp, periods of compromised blood flow during aortic cross-clamp time, and lower nadir hematocrit were associated with the risk of AKI, while mean blood flow, bladder temperature, central venous pressure, and mixed venous oxygen saturation were not. Patient characteristics independently associated with AKI were advanced age, higher body mass index, hypertension, diabetes mellitus, atrial fibrillation, lower left ventricular ejection fraction, estimated glomerular filtration rate <60 or >90 mL/min/m2 , and preoperative hemoglobin concentration below or above the normal sex-specific range. CONCLUSIONS: To reduce the risk of AKI after cardiac surgery, aortic clamp time and CPB time should be kept short, and low hematocrit and periods of compromised blood flow during aortic cross-clamp time should be avoided if possible.

Risk factors and treatment of oxygenator high-pressure excursions during cardiopulmonary bypass.

INTRODUCTION: A high-pressure excursion (HPE) is a sudden increase in oxygenator inlet pressure during cardiopulmonary bypass (CPB). The aims of this study were to identify factors associated with HPE, to describe a treatment protocol utilizing epoprostenol in severe cases, and to assess early outcome in HPE patients. METHODS: Patients who underwent cardiac surgery with cardiopulmonary bypass at Sahlgrenska University Hospital 2016-2018 were included in a retrospective observational study. Pre- and post-operative data collected from electronic health records, local databases, and registries were compared between HPE and non-HPE patients. Factors associated with HPE were identified with logistic regression models. RESULTS: In total, 2024 patients were analyzed, and 37 (1.8%) developed HPE. Large body surface area (adjusted Odds Ratio (aOR): 1.43 per 0.1 m2; 95% confidence interval (CI): 1.16-1.76, p < 0.001), higher hematocrit during CPB (aOR: 1.20 per 1%; (1.09-1.33), p < 0.001), acute surgery (aOR: 2.98; (1.26-6.62), p = 0.018), and previous stroke (aOR: 2.93; (1.03-7.20), p = 0.027) were independently associated with HPE. HPE was treated with hemodilution (n = 29, 78.4%), and/or extra heparin (n = 23, 62.2%), and/or epoprostenol (n = 12, 32.4%). No oxygenator change-out was necessary. While there was no significant difference in 30-day mortality (2.7% vs 3.2%, p = 1.0), HPE was associated with a higher perioperative stroke rate (8.1% vs 1.8%, aOR 5.09 (1.17-15.57), p = 0.011). CONCLUSIONS: Large body surface area, high hematocrit during CPB, previous stroke and acute surgery were independently associated with HPE. A treatment protocol including epoprostenol appears to be a safe option. Perioperative stroke rate was increased in HPE patients.

Is blood a necessary component of the perfusate during isolated limb perfusion - a randomized controlled trial.

Background: Isolated limb perfusion (ILP) is a treatment option for malignancies localized to an extremity and is performed by surgical isolation of the limb which is connected to an extracorporeal circulation system. A high concentration of a chemotherapeutic agent is perfused through the limb, while systemic toxicity is avoided. Currently, the use of packed red blood cells in the priming solution is the norm during ILP. The aim of this study was to investigate the possibility to replace an erythrocyte-based prime solution with a crystalloid-based prime solution while maintaining the regional metabolic oxygen demand during ILP. Methods: In a single-center, randomized controlled, non-blinded, non-inferiority clinical trial, 21 patients scheduled for treatment with ILP were included and randomized 1:1 to either an erythrocyte-based prime solution (control) or a crystalloid-based prime solution (intervention). Results: There was a significant difference in lactate level (mmol/L) during the perfusion between the intervention group and the control group (1.6 ± 0.4 vs. 3.6 ± 0.7, p = .001). No significant differences in oxygen extraction (%) (22 ± 11 vs. 14 ± 4, p = .06), oxygen delivery (ml/min) (90 ± 49 vs. 108 ± 38, p = .39), oxygen consumption (ml/min) (14 ± 2 vs. 14 ± 5, p = .85), regional central venous saturation (%) (83 ± 10 vs. 91 ± 4, p = .07) or INVOS (%) (76 ± 14 vs. 81 ± 11, p = .42) were found between the intervention group and the control group. Conclusion: This study showed no significant improvement with the addition of packed red blood cells into the prime solution in ensuring the metabolic oxygen demand in the treated extremity during ILP, and we, therefore, recommend that a crystalloid-based prime solution should be used.

Minimally invasive isolated limb perfusion - technical details and initial outcome of a new treatment method for limb malignancies.

OBJECTIVE: Isolated limb perfusion (ILP) and isolated limb infusion (ILI) are treatment options for patients with locally advanced melanomas and sarcomas of the extremities. ILP potentially have higher response rates, but requires open surgery for vascular access, whereas ILI is minimally invasive and easier to perform. We now present the technical details and outcome of a new approach to ILP by a minimally invasive vascular access (MI-ILP). METHODS: Six patients, five with melanoma in-transit metastases and one with squamous cell carcinoma, were included in a phase I feasibility trial. Percutaneous vascular access of the extremity vessels was performed and the inserted catheters were then connected to a perfusion system. RESULTS: All six treated patients underwent the procedure without the need for conversion to open surgery. The median operating time was 164 min and the median leakage rate was 0.1%. The complete response rate was 67%. Four patients (67%) had a Wieberdink grade II reaction and two patients (33%) had a grade III reaction. CONCLUSIONS: MI-ILP is feasible and gives the same treatment characteristics as open ILP, but with the advantage of a minimally invasive vascular access.

Epoprostenol for the treatment of increasing oxygenator pressure drop during cardiopulmonary bypass. A case report.

A change of oxygenator during cardiopulmonary bypass is a technically high-risk procedure with potential for a serious adverse event for the patient. This case report describes a case of increased pressure drop and pre-oxygenator blood pressure during cardiopulmonary bypass successfully treated with pre-oxygenator-administered epoprostenol.

Cardiopulmonary bypass management and risk of new-onset atrial fibrillation after cardiac surgery.

OBJECTIVES: Cardiopulmonary bypass (CPB) management may potentially play a role in the development of new-onset atrial fibrillation (AF) after cardiac surgery. The aim of this study was to explore this potential association. METHODS: Patients who underwent coronary artery bypass grafting and/or valvular surgery during 2016-2020 were included in an observational single-centre study. Data collected from the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies registry and a local CPB database were merged. Associations between individual CPB variables (CPB and aortic clamp times, arterial and central venous pressure, mixed venous oxygen saturation, blood flow index, bladder temperature and haematocrit) and new-onset AF were analysed using multivariable logistic regression models adjusted for patient characteristics, comorbidities and surgical procedure. RESULTS: Out of 1999 patients, 758 (37.9%) developed new-onset AF. Patients with new-onset postoperative AF were older, had a higher incidence of previous stroke, worse renal function and higher EuroSCORE II and CHA2DS2-VASc scores and more often underwent valve surgery. Longer CPB time [adjusted odds ratio 1.05 per 10 min (95% confidence interval 1.01-1.08); P = 0.008] and higher flow index [adjusted odds ratio 1.21 per 0.2 l/m2 (95% confidence interval 1.02-1.42); P = 0.026] were associated with an increased risk for new-onset AF, while the other variables were not. A sensitivity analysis only including patients with isolated coronary artery bypass grafting supported the primary analyses. CONCLUSIONS: CPB management following current guideline recommendations appears to have minor or no influence on the risk of developing new-onset AF after cardiac surgery.

Effects of atrial natriuretic peptide on renal function during cardiopulmonary bypass: a randomized pig model.

OBJECTIVES: Acute kidney injury is a well-known complication after cardiac surgery and cardiopulmonary bypass (CPB). In this experimental animal study, we evaluated the effects of atrial natriuretic peptide (ANP) on renal function, perfusion, oxygenation and tubular injury during CPB. METHODS: Twenty pigs were blindly randomized to continuous infusion of either ANP (50 ng/kg/min) or placebo before, during and after CPB. Renal blood flow as well as cortical and medullary perfusion was measured. Blood was repeatedly sampled from the renal vein. Glomerular filtration rate was measured by infusion clearance of 51Cr-EDTA. RESULTS: Glomerular filtration rate was higher (P < 0.001), whereas renal blood flow or renal oxygen delivery was not affected by ANP during CPB. Renal oxygen consumption did not differ between groups during CPB, whereas renal oxygen extraction was higher in the ANP group (P = 0.03). Urine flow and sodium excretion were higher in the ANP group during CPB. Blood flow in the renal medulla, but not in the cortex, dropped during CPB, an effect that was not seen in the animals that received ANP. CONCLUSIONS: ANP improved renal function during CPB. Despite impaired renal oxygenation, ANP did not cause tubular injury, suggesting a renoprotective effect of ANP during CPB. Also, CPB induced a selectively reduced blood flow in the renal medulla, an effect that was counteracted by ANP.

Impact of Cardiopulmonary Bypass Flow on Renal Oxygenation in Patients Undergoing Cardiac Operations.

BACKGROUND: Cardiac surgery with cardiopulmonary bypass (CPB) is associated with acute kidney injury, and the risk increases with low oxygen delivery during CPB. We hypothesized that renal oxygenation could be improved at higher than normal CPB flow rates. METHODS: After ethical approval and informed consent, 17 patients with normal serum creatinine undergoing normothermic CPB were included and received pulmonary artery and renal vein catheters after anesthesia induction for measurements of systemic and renal variables. Renal oxygen extraction, a direct measure of the renal oxygen delivery/renal oxygen consumption ratio, and renal filtration fraction were measured, the latter by renal extraction of 51chromium-ethylenediaminetetraacetic acid. After start of CPB and aortic cross-clamp, the pump flow rate was randomly varied between 2.4, 2.7, and 3.0 L · min-1 · m-2, and measurements were made after 10 minutes at each flow rate. RESULTS: Renal oxygen extraction increased by 30% at a flow rate of 2.4 L · min-1 · m-2 versus pre-CPB (p < 0.05). At a flow rate of 2.7 and 3.0 L · min-1 · m-2, Renal oxygen extraction was 12% (p < 0.05) and 23% (p < 0.01) lower, respectively, compared with 2.4 L · min-1 · m-2. This corresponds to a 14% and 30% improvement, respectively, of the renal oxygen supply/demand relationship. Filtration fraction was not affected by changes in flow rate, indicating that the glomerular filtration rate increased in proportion to the increase in renal perfusion. CONCLUSIONS: The impaired renal oxygenation seen during CPB is ameliorated by an increase in CPB flow rate. Thus, one way to protect the kidneys during CPB could be to use a higher flow rate than the one traditionally used.