Inflammatory Effects of Blood-Air Interface in a Porcine Cardiopulmonary Bypass Model

Does remote ischemic preconditioning affect the systemic inflammatory response by modulating presepsin levels?

OBJECTIVE

We investigated the effect of Remote Ischemic Preconditioning (RIPC) on the inflammatory response during CPB by means of serum presepsin levels at preoperative and postoperative 1st and 24th h.

METHODS

In this prospective, randomized, cross-sectional study we included 81 patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass (CPB). Patients were randomized and RIPC was applied to 40 patients in the study group before anesthesia. The remaining 41 patients were determined as the control group. The relationships between RIPC and factors such as presepsin, C-reactive protein (CRP), and leukocyte levels were investigated.

RESULTS

There was no significant difference between the groups in postoperative leukocyte and CRP values (p = 0.52, p = 0.13, respectively). When the preoperative and postoperative first hour presepsin values of the patients were compared, no significant difference was found in the control group (p = 0.17), but a significant difference was found in the study group (p < 0.05). When the presepsin values were compared between the groups, a significant difference was found only in the postoperative first hour value (p < 0.05).

CONCLUSIONS

It was observed that RIPC application caused to increase the presepsin levels in the postoperative first hour significantly in the study group (p < 0.05).

Initial experience and outcomes with a hybrid extracorporeal membrane oxygenation and cardiopulmonary bypass circuit for lung transplantation

Background

The utilization of extracorporeal life support (ECLS) for intraoperative support during lung transplantation has increased over the past decade. Although veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has recently emerged as the preferred modality over cardiopulmonary bypass (CPB), many centers continue to use both forms of ECLS during lung transplantation. Our novel hybrid VA-ECMO/CPB circuit allows for seamless transition from VA-ECMO to CPB at a significant cost savings compared to a standalone VA-ECMO circuit. This study describes our initial experience and outcomes in the first 100 bilateral lung transplantations using this novel hybrid VA-ECMO/CPB circuit.

Methods

Medical records from September 2017 to May 2021 of the first 100 consecutive patients undergoing bilateral lung transplantation with intraoperative hybrid VA-ECMO support were examined retrospectively. We excluded patients with single lung transplants, retransplantations, preoperative ECLS bridging, and veno-venous (VV) ECMO and those supported with CPB only. Perioperative recipient, anesthetic, perfusion variables, and outcomes were assessed.

Results

Of the 100 patients supported with VA-ECMO, 19 were converted intraoperatively to CPB. Right ventricular dysfunction was seen in 37% of patients, and the median mean pulmonary artery pressure was 28 mm Hg. No oxygenator clotting was observed with a median heparin dose of 13,000 units in the VA-ECMO group. Primary graft dysfunction grade 3 at 72 hours was observed in 10.1% of all patients and observed 1-year mortality was 4%.

Conclusions

The use of a hybrid VA-ECMO/CPB circuit in our institution allows for rapid conversion to CPB with acceptable outcomes across a diverse recipient group at a significantly reduced cost compared to standalone VA-ECMO circuits.

Effects of extracorporeal circulation with different time on platelet count after cardiac surgery: a retrospective study based on medical records

Our objective was to observe the effects of extracorporeal circulation (ECC) with different time on platelet count in patients undergoing cardiac surgery. A total of 427 patients who underwent elective cardiac surgery under ECC in affiliated hospital of north Sichuan medical college from January 1, 2018 to July 31, 2021 were divided into three groups according to ECC time. We concluded that thrombocytopenia was common after ECC, maximum drop of the platelet counts after ECC was usually seen on the second day after ECC, and platelet counts started to recover on the fifth day after ECC. With the extension of ECC time, the drop in platelet counts is more pronounced, the volume of perioperative blood loss and blood products transfusion are more, and the recovery level and speed of platelet counts is lower.

Hemostatic Complications During Neonatal Extracorporeal Membrane Oxygenation: Roller Pump and Centrifugal Pump Driven Circuits

Recently three different neonatal extracorporeal membrane oxygenation (ECMO) circuits have been employed in our clinic. These circuits were compared for clotting and bleeding complications. Initially, we used an ECMO circuit containing a roller pump and venous bladder without severe complications. Manufacturing of circuit components was discontinued, necessitating the replacement of this circuit by a circuit with a centrifugal pump with 3/8 inch inlet and outlet. Acute increase of oxygenator resistance requiring emergency changeout became unexpectedly a regularly occurring complication. The increase in resistance was suspected to be caused by oxygenator clotting, although oxygenator function was preserved. To prevent this complication, we changed to a levitating centrifugal pump with 1/4 inch inlet and outlet, after which no oxygenator malfunction has been observed. Macroscopic and electron microscopic analysis demonstrates that small clots are formed within the circuit, presumably in or near the centrifugal pump, which are transported to the oxygenator and clog up the hollow fiber layer at the inlet side, barely penetrating the oxygenator beyond this first layer. Our results suggest that low blood velocities accompanied with recirculation of blood within or near the centrifugal pump and/or heat generation within the pump could contribute to the formation of these clots.

Turbulence in surgical suction heads as detected by MRI

BACKGROUND

Blood loss is common during surgical procedures, especially in open cardiac surgery. Allogenic blood transfusion is associated with increased morbidity and mortality. Blood conservation programs in cardiac surgery recommend re-transfusion of shed blood directly or after processing, as this decreases transfusion rates of allogenic blood. But aspiration of blood from the wound area is often associated with increased hemolysis, due to flow induced forces, mainly through development of turbulence.

METHODS

We evaluated magnetic resonance imaging (MRI) as a qualitative tool for detection of turbulence. MRI is sensitive to flow; this study uses velocity-compensated T1-weighted 3D MRI for turbulence detection in four geometrically different cardiotomy suction heads under comparable flow conditions (0-1250 mL/min).

RESULTS

Our standard control suction head Model A showed pronounced signs of turbulence at all flow rates measured, while turbulence was only detectable in our modified Models 1-3 at higher flow rates (Models 1 and 3) or not at all (Model 2).

CONCLUSIONS

The comparison of flow performance of surgical suction heads with different geometries via acceleration-sensitized 3D MRI revealed significant differences in turbulence development between our standard control Model A and the modified alternatives (Models 1-3). As flow conditions during measurement have been comparable, the specific geometry of the respective suction heads must have been the main factor responsible. The underlying mechanisms and causative factors can only be speculated about, but as other investigations have shown, hemolytic activity is positively associated with degree of turbulence. The turbulence data measured in this study correlate with data from other investigations about hemolysis induced by surgical suction heads. The experimental MRI technique used showed added value for further elucidating the underlying physical phenomena causing blood damage due to non-physiological flow.

Nitric Oxide on Extracorporeal Life Support-Circuit Modifications for a Safe Therapy

Nitric oxide (NO) incorporation into the sweep gas of the extracorporeal life support (ECLS) circuit has been proposed as a strategy to ameliorate the insults caused by the systemic inflammatory response. This technical study describes circuit modifications allowing nitric oxide to be incorporated into the circuit and describing and validating the oxygenator sweep flow rates necessary to achieve consistent safe delivery of the therapy. For patients requiring sweep rates less than 2 L/min, a simplified setup, incorporating a pressure relief valve/low flow meter in the gas delivery line, was placed in line between the blender/NO injector module and the NO sampling port/oxygenator. This setup allows titration of sweep to low flows without the need to blend in CO₂ while maintaining the manufacturer recommendation of a minimum 2 L/min of sweep gas to safely deliver NO without nitric dioxide (NO₂) buildup. This setup was tested three times at three different FiO₂ rates and eleven different desired low sweep flows to test for reproducibility and safety to build an easy-to-follow chart for making gas flow changes. For patients requiring oxygenator sweep rates greater than 2 L/min, the pressure relief valve/low flow meter apparatus is not needed. Maintaining consistent sweep rate and nitric oxide delivery is required in order to utilize this therapy in ECLS. We demonstrated gas delivery across all flow rates. There were no issues delivering 20 parts per million of NO and negligible NO₂ detection. The results from testing this setup were used to provide the specialist a chart at which to set the low flow meter to produce the desired flow rate at which the patient needs. This has been used clinically on 15 ECLS patients with success.

Neutrophil Counts, Neutrophil-to-Lymphocyte Ratio, and Systemic Inflammatory Response Index (SIRI) Predict Mortality after Off-Pump Coronary Artery Bypass Surgery

Background: Several perioperative inflammatory markers are postulated to be significant factors for long-term survival after off-pump coronary artery bypass surgery (OPCAB). Hematological parameters, whether single or combined as indices, provide higher predictive values. Methods: The study group comprised 538 consecutive patients (125 (23%) females and 413 (77%) males) with a mean age of 65 ± 9 years, who underwent OPCAB with a mean follow-up time of 4.7 ± 1.7 years. This single-center retrospective analysis included perioperative inflammatory markers such as the neutrophil-to-lymphocyte ratio (NLR), systemic inflammatory response index (SIRI), aggregate index of systemic inflammation (AISI), and systemic inflammatory index (SII). Results: Multivariable analysis identified levels of neutrophils above 4.3 × 109/L (HR 13.44, 95% CI 1.05−3.68, p = 0.037), values of SIRI above 5.4 (HR 0.29, 95% CI 0.09−0.92, p = 0.036) and values of NLR above 3.5 (HR 2.21, 95% CI 1.48−3.32, p < 0.001) as being significant predictors of long-term mortality. The multifactorial models revealed the possibility of strong prediction by combining preoperative factors (COPD, stroke, PAD, and preoperative PLR) and postoperative neutrophil counts (p = 0.0136) or NLR (p = 0.0136) or SIRI (p = 0.0136). Conclusions: Among the postoperative inflammatory indices, the levels of neutrophils, NLR, and SIRI are the most prominent markers for long-term survival after off-pump coronary artery bypass surgery, when combined with preoperative characteristics.

Risk factors for postoperative delirium after cardiac surgical procedures with cardioplegic arrest

OBJECTIVES

The pathophysiology of delirium after cardiac surgery is complex. The present study aims to determine perioperative risk factors and construct a scoring system for postoperative delirium based on the type of surgery.

METHODS

Three hundred patients undergoing coronary artery bypass grafting (CABG; n = 150) or valve and/or aortic surgery ± CABG (n = 150) were retrospectively evaluated.

RESULTS

The incidence of delirium (32%) was similar in subgroups (28.7% and 33.33%, P = 0.384). Delirium patients were older [71.3 (standard deviation: 8.5) vs 66.6 (standard deviation: 9.5), P < 0.001; 70.0 (standard deviation: 9.6) vs 62.5 (standard deviation: 12.6), P < 0.001] and required more packed red blood cell units [2.1 (standard deviation: 2.1) vs 4.2 (standard deviation: 4.0), P < 0.001; 2.4 (standard deviation: 3.3) vs 5.4 (standard deviation: 5.9), P < 0.001] and fresh frozen plasma units [6.1 (standard deviation: 2.9) vs. 8.0 (standard deviation: 4.2), P < 0.001; 6.3 (standard deviation: 3.4) vs 10.8 (standard deviation: 7.2), P < 0.001] in CABG and valve/aortic subgroups, respectively. Delirium was associated with longer operation time [298.3 (standard deviation: 98.4) vs 250.6 (standard deviation: 67.8) min, P < 0.001], cardiopulmonary bypass (CPB) time [171.5 (standard deviation: 54.9) vs 140.98 (standard deviation: 45.8) min, P < 0.001] and cardiac arrest time [112 (standard deviation: 35.9) vs 91.9 (standard deviation: 28.6), P < 0.001] only in the valve/aortic group (versus non-delirium). Multivariate regression analysis identified an association between delirium and age [odds ratio: 1.056 (95% confidence interval: 1.002-1.113), P = 0.041], CPB time [odds ratio: 1.1014 (95% confidence interval: 1.004-1.025), P = 0.007], fresh frozen plasma transfusion [odds ratio: 1.127 (95% confidence interval: 1.006-1.262), P = 0.039] and atrial fibrillation [odds ratio: 4.801 (95% confidence interval: 1.844-12.502), P < 0.001] after valve/aortic surgery (area under the curve 0.835, P < 0.001) and between delirium and age [odds ratio: 1.089 (95% confidence interval: 1.023-1.160), P = 0.007] and ventilation time [odds ratio: 1.068 (95% confidence interval: 1.026-1.113), P = 0.001] after isolated CABG (area under the curve 0.798, P < 0.001). The cross-validation of the results by k-fold logistic regression revealed for the entire patient cohort an overall average accuracy of the prediction model of 0.764, with a false-positive rate of 0.052 and a false-negative rate of 0.18.

CONCLUSIONS

Age, CPB time, ventilation, transfusion and atrial fibrillation are differently associated with delirium depending on the operative characteristics. Optimization of intraoperative parameters and use of risk calculators may enable early institution of pharmacotherapy and improve overall outcome after cardiac surgery.

Impact of left ventricular inspection employing cardiopulmonary bypass on outcome after implantation of left ventricular assist device

BACKGROUND

Cardiopulmonary bypass (CPB) during left ventricular assist device (LVAD) implantation provides circulatory support and allows for safe inspection of the left ventricle (LV), whereas circulatory support by veno-arterial extracorporeal life support (va-ECLS) or off-pump implantation may reduce postoperative bleeding and inflammatory response.

METHODS

Retrospective analysis of 616 consecutive adult patients who received an LVAD via median sternotomy between January 1, 2015 and December 31, 2019. All patients undergoing concomitant intracardiac procedures other than closure of persistent foramen ovale or atrial septal defect and redo surgeries were excluded from the analysis. The remaining patients (n = 222) were divided into two groups and 1:1 propensity score-matched regarding preoperative parameters: patients who underwent LVAD implantation with LV inspection employing CPB (CPB group, n = 62) and without LV inspection on va-ECLS or off-pump (non-CPB group, n = 62).

RESULTS

The groups were well balanced with regard to preoperative baseline characteristics (standard difference <0.1). Patients in the CPB group required more blood transfusions (median 2 vs. 0 units, p = 0.031) during surgery and in the first 24 h afterwards. The median intensive care unit stay was longer in the CPB group (18 vs. 11 days, p = 0.021). The CPB group showed an absence of perioperative stroke and a smaller number of events per patient-year for postoperative ischemic stroke (0.02 vs. 0.12, p = 0.003). 30-day survival (87% vs. 87.1%) and 1-year survival (80.3% vs. 74%) were similar in both groups (p = 0.78).

CONCLUSION

Visual LV inspection on CPB may reduce the risk of postoperative ischemic stroke. Despite the negative effects of employing CPB in lieu of other intraoperative strategies, survival was similar in both groups.

Nitric Oxide Attenuates the Inflammatory Effects of Air During Extracorporeal Circulation

Cardiopulmonary bypass causes a systemic inflammatory response reaction that may contribute to postoperative complications. One cause relates to the air/blood interface from the extracorporeal circuit. The modulatory effects of blending nitric oxide (NO) gas into the ventilation/sweep gas of the membrane lung was studied in a porcine model of air-induced inflammation in which NO gas was added and compared with controls with or without an air/blood interface. Healthy swine were supported on partial bypass under four different test conditions. Group 1: no air exposure, group 2: air alone, group 3: air plus 50 ppm NO, and group 4: air plus 500 ppm NO. The NO gas was blended into the ventilation/sweep site of the membrane lung. The platelets and leucocytes were activated by air alone. Addition of NO to the sweep gas attenuated the inflammatory response created by the air/blood interface in this model.

Dialysis-Induced Cardiovascular and Multiorgan Morbidity

Hemodialysis has saved many lives, albeit with significant residual mortality. Although poor outcomes may reflect advanced age and comorbid conditions, hemodialysis per se may harm patients, contributing to morbidity and perhaps mortality. Systemic circulatory "stress" resulting from hemodialysis treatment schedule may act as a disease modifier, resulting in a multiorgan injury superimposed on preexistent comorbidities. New functional intradialytic imaging (i.e., echocardiography, cardiac magnetic resonance imaging [MRI]) and kinetic of specific cardiac biomarkers (i.e., Troponin I) have clearly documented this additional source of end-organ damage. In this context, several factors resulting from patient-hemodialysis interaction and/or patient management have been identified. Intradialytic hypovolemia, hypotensive episodes, hypoxemia, solutes, and electrolyte fluxes as well as cardiac arrhythmias are among the contributing factors to systemic circulatory stress that are induced by hemodialysis. Additionally, these factors contribute to patients' symptom burden, impair cognitive function, and finally have a negative impact on patients' perception and quality of life. In this review, we summarize the adverse systemic effects of current intermittent hemodialysis therapy, their pathophysiologic consequences, review the evidence for interventions that are cardioprotective, and explore new approaches that may further reduce the systemic burden of hemodialysis. These include improved biocompatible materials, smart dialysis machines that automatically may control the fluxes of solutes and electrolytes, volume and hemodynamic control, health trackers, and potentially disruptive technologies facilitating a more personalized medicine approach.

Air, inflammation and biocompatibility of the extracorporeal circuits

The inflammatory response in cardiac surgery using extracorporeal circulation (ECC) has been widely discussed in the literature with analysis on cytokines released in humans; demonstrating manifold trigger causes. To mitigate this response-mainly linked to the contact and recognition by the blood of a "non-self" surface-many efforts have been made to make the circuits of the extra-corporeal circulation "biomimetics"; trying to emulate the cardio-vascular system. In other words, biomedical companies have developed many biocompatible products in order to reduce the invasiveness of the ECC. One of the techniques used to reduce the contact of blood with "nonself" surfaces is the "coating" of the internal surfaces of the ECC. This can be done with phospholipidic, electrically neutral, and heparin derivates with anticoagulant activity. The coating can be divided into two categories: the "passive coating" with Phosphorylcholine by biomedical companies and the administration of albumin added to the "priming" during the filling of the circuit by the perfusionist. Alternatively, we have the "active" coating: treatment of the internal surfaces in contact with the blood with neutral proteins and heparin. The latter are different according to the production company, but the aim is always to maintain high levels of systemic and local anticoagulation, inactivating the "contact" coagulation between the blood and the surfaces. A recent study demonstrates that the use of an "active coating" is associated with better preservation of the endothelial glycocalyx compared with "passive coating" circuits.