Nitric oxide delivery during cardiopulmonary bypass reduces acute kidney injury: A randomized trial

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

Assessment of continuous low-dose and high-dose burst of inhaled nitric oxide in spontaneously breathing COVID-19 patients: A randomized controlled trial

BACKGROUND

Inhaled nitric oxide (iNO) showed to improve oxygenation at low doses by reducing intrapulmonary shunt and to display antiviral properties at high doses. To assess the safety and potential benefits, we designed an exploratory clinical trial comparing low-dose with intermittent high-dose iNO to only intermittent high-dose iNO in hypoxemic COVID-19 patients.

METHODS

In this single-center interventional non-inferiority randomized trial (ClinicalTrials.gov, NCT04476992), twenty oxygen-dependent COVID-19 patients were randomly assigned to the high-dose (200 ppm for 30 min) + continuous low-dose (20 ppm) iNO group (iNO200/20) or the high-dose iNO group (iNO200). Methemoglobinemia (MetHb) assessed 48 h after iNO initiation was the primary endpoint. Reverse-transcription polymerase chain reaction for SARS-CoV-2, inflammatory markers during hospitalization, and heart ultrasounds during the iNO200 treatments were evaluated.

RESULTS

MetHb difference between iNO groups remained within the non-inferiority limit of 3 %, indicating comparable treatments despite being statistically different (p-value<0.01). Both groups presented similar SpO2/FiO2 ratio at 48 h (iNO200 vs. iNO200/20 341[334-356] vs. 359 [331-380], respectively, p-value = 0.436). Both groups showed the same time to SARS-CoV-2 negativization, hospital length of stay, and recovery time. iNO-treated patients showed quicker SARS-CoV-2 negativization compared to a similar group of non-iNO patients (HR 2.57, 95%CI 1.04-6.33). During the 228 treatments, iNO200 and iNO200/20 groups were comparable for safety, hemodynamic stability, and respiratory function improvement.

CONCLUSIONS

iNO200/20 and iNO200 are equally safe in non-intubated patients with COVID-19-induced respiratory failure with regards to MetHb and NO2. Larger studies should investigate whether iNO200/20 leads to better outcomes compared to non-iNO treated patients.

Inhaled nitric oxide and postoperative outcomes in cardiac surgery with cardiopulmonary bypass: A systematic review and meta-analysis

Cardiac surgeries under cardiopulmonary bypass (CPB) are complex procedures with high incidence of complications, morbidity and mortality. The inhaled nitric oxide (iNO) has been frequently used as an important composite of perioperative management during cardiac surgery under CPB. We conducted a meta-analysis of published randomized clinical trials (RCTs) to assess the effects of iNO on reducing postoperative complications, including the duration of postoperative mechanical ventilation, length of intensive care unit (ICU) stay, length of hospital stay, mortality, hemodynamic improvement (the composite right ventricular failure, low cardiac output syndrome, pulmonary arterial pressure, and vasoactive inotropic score) and myocardial injury biomarker (postoperative troponin I levels). Subgroup analyses were performed to assess the effect of modification and interaction. These included iNO dosage, the timing and duration of iNO therapy, different populations (children and adults), and comparators (other vasodilators and placebo or standard care). A comprehensive search for iNO and cardiac surgery was performed on online databases. Twenty-seven studies were included after removing the duplicates and irrelevant articles. The results suggested that iNO could reduce the duration of mechanical ventilation, but had no significance in the ICU stay, hospital stay, and mortality. This may be attributed to the small sample size of the most included studies and heterogeneity in timing, dosage and duration of iNO administration. Well-designed, large-scale, multicenter clinical trials are needed to further explore the effect of iNO in improving postoperative prognosis in cardiovascular surgical patients.

Perioperative acetaminophen is associated with reduced acute kidney injury after cardiac surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (AKI) is associated with increased postoperative morbidity and mortality. Evidence suggests an association between perioperative acetaminophen administration and decreased incidence of postoperative AKI in pediatric cardiac surgery patients; however, an effect in adults is unknown.

METHODS

All patients (n = 6192) undergoing coronary and/or valve surgery with a recorded Society of Thoracic Surgeons (STS) risk score at our institution between 2010 and 2018 were stratified by acetaminophen exposure on the day of surgery using institutional pharmacy records. AKI was determined using the Kidney Disease: Improving Global Outcomes (KDIGO) staging criteria. Logistic regression was used to analyze the association between perioperative acetaminophen and postoperative kidney injury or STS major morbidity. A sensitivity analysis using propensity score matching on the STS predicted risk of renal failure and cardiopulmonary bypass time was performed to account for time bias.

RESULTS

Perioperative acetaminophen exposure was associated with lower odds of stage 1 to 3 acute kidney injury (odds ratio [OR], 0.68; 95% CI, 0.56-0.83; P < .001) and decreased prolonged postoperative ventilation (OR, 0.53; 95% CI, 0.37-0.76; P < .001). A sensitivity analysis provided well-balanced (standard mean difference <0.10) groups of 401 pairs, in which acetaminophen was associated with a decreased incidence of postoperative AKI (OR, 0.7; 95% CI, 0.52-0.94; P = .016).

CONCLUSIONS

Exposure to acetaminophen on the day of surgery was associated with a decreased incidence of AKI in our patients undergoing cardiac surgery. These data serve as a measure of effect size to further explore the therapeutic potential of acetaminophen to reduce postoperative AKI after cardiac surgery and to elucidate the mechanisms involved.

The biological role and future therapeutic uses of nitric oxide in extracorporeal membrane oxygenation, a narrative review

BACKGROUND

Nitric oxide (NO) is a gas naturally produced by the human body that plays an important physiological role. Specifically, it binds guanylyl cyclase to induce smooth muscle relaxation. NO's other protective functions have been well documented, particularly its protective endothelial functions, effects on decreasing pulmonary vascular resistance, antiplatelet, and anticoagulation properties. The use of nitric oxide donors as vasodilators has been known since 1876. Inhaled nitric oxide has been used as a pulmonary vasodilator and to improve ventilation perfusion matching since the 1990s. It is currently approved by the United States Food and Drug Administration for neonates with hypoxic respiratory failure, however, it is used off-label for acute respiratory distress syndrome, acute bronchiolitis, and COVID-19.

PURPOSE

In this article we review the currently understood biological action and therapeutic uses of NO through nitric oxide donors such as inhaled nitric oxide. We will then explore recent studies describing use of NO in cardiopulmonary bypass and extracorporeal membrane oxygenation and speculate on NO's future uses.

Acute Kidney Injury after Cardiac Surgery: Prediction, Prevention, and Management

Acute kidney injury (AKI) is a common complication in cardiac surgery patients, with a reported incidence of 20 to 30%. The development of AKI is associated with worse short- and long-term mortality, and longer hospital length of stay. The pathogenesis of cardiac surgery-associated AKI is poorly understood but likely involves an interplay between preoperative comorbidities and perioperative stressors. AKI is commonly diagnosed by using increases in serum creatinine or decreased urine output and staged using a standardized definition such as the Kidney Disease Improving Global Outcomes classification. Novel biomarkers under investigation may provide earlier detection and better prediction of AKI, enabling mitigating therapies early in the perioperative period. Recent clinical trials of cardiac surgery patients have demonstrated the benefit of goal-directed oxygen delivery, avoidance of hyperthermic perfusion and specific fluid and medication strategies. This review article highlights both advances and limitations regarding the prevention, prediction, and treatment of cardiac surgery-associated AKI.

Exogenous nitric oxide delivery protects against cardiopulmonary bypass-associated acute kidney injury: Histologic and serologic evidence from an ovine model

OBJECTIVE

Several human studies have associated nitric oxide administration via the cardiopulmonary bypass circuit with decreased incidence of cardiopulmonary bypass-associated acute kidney injury, but histopathologic and serologic evidence of nitric oxide efficacy for acute kidney injury attenuation are lacking.

METHODS

By using a survival ovine model (72 hours), acute kidney injury was induced by implementing low-flow cardiopulmonary bypass for 2 hours, followed by full-flow cardiopulmonary bypass for 2 hours. The nitric oxide cohort (n = 6) received exogenous nitric oxide through the cardiopulmonary bypass circuit via the oxygenator, and the control group (n = 5) received no nitric oxide. Serial serologic biomarkers and renal histopathology were obtained.

RESULTS

Baseline characteristics (age, weight) and intraoperative parameters (cardiopulmonary bypass time, urine output, heart rate, arterial pH, and lactate) were equivalent (P > .10) between groups. Postoperatively, urine output, heart rate, respiratory rate, and peripheral arterial saturation were equivalent (P > .10) between groups. Post-cardiopulmonary bypass creatinine elevations from baseline were significantly greater in the control group versus the nitric oxide group at 16, 24, and 48 hours (all P < .05). Histopathologic evidence of moderate/severe acute kidney injury (epithelial necrosis, tubular slough, cast formation, glomerular edema) occurred in 60% (3/5) of the control group versus 0% (0/6) of the nitric oxide group. Cortical tubular epithelial cilia lengthening (a sensitive sign of cellular injury) was significantly greater in the control group than in the nitric oxide group (P = .012).

CONCLUSIONS

In a survival ovine cardiopulmonary bypass model, nitric oxide administered with cardiopulmonary bypass demonstrated serologic and histologic evidence of renal protection from acute kidney injury. These results provide insight into 1 potential mechanism for cardiopulmonary bypass-associated acute kidney injury and supports continued study of nitric oxide via cardiopulmonary bypass circuit for prevention of acute kidney injury.

The beneficial use of nitric oxide during cardiopulmonary bypass on postoperative outcomes in children and adult patients: a systematic review and meta-analysis of 2897 patients

PURPOSE

Investigate inhaled nitric oxide's influence on mortality rates, mechanical ventilation and cardiopulmonary bypass duration, and length of stay in the intensive care unit and hospital when administered during cardiopulmonary bypass.

METHODS

Following the PRISMA guidelines, we searched four electronic databases (PubMed, EMBASE, Cochrane Library, and Web of Science) up to 4th March 2023. The protocol was registered in the PROSPERO database with ID: CRD42023423007. Using Review Manager software, we reported outcomes as risk ratios (RRs) or mean difference (MD) and confidence intervals (CIs).

RESULTS

The meta-analysis included a total of 17 studies with 2897 patients. Overall, there were no significant differences in using nitric oxide over control concerning mortality (RR = 1.03, 95% CI 0.73 to 1.45; P = 0.88) or cardiopulmonary bypass duration (MD = -0.14, 95% CI - 0.96 to 0.69; P = 0.74). The intensive care unit days were significantly lower in the nitric oxide group than control (MD = -0.80, 95% CI - 1.31 to -0.29; P = 0.002). Difference results were obtained in terms of the length of stay in the hospital according to sensitivity analysis (without sensitivity [MD = -0.41, 95% CI - 0.79 to -0.02; P = 0.04] vs. with sensitivity [MD = -0.31, 95% CI - 0.69 to 0.07; P = 0.11]. Subgroup analysis shows that, in children, nitric oxide was favored over control in significantly reducing the duration of mechanical ventilation (MD = -4.58, 95% CI - 5.63 to -3.53; P < 0.001).

CONCLUSION

Using inhaled nitric oxide during cardiopulmonary bypass reduces the length of stay in the intensive care unit, and for children, it reduces the duration of mechanical ventilation.

Dapagliflozin protects against doxorubicin-induced nephrotoxicity associated with nitric oxide pathway-A translational study

Doxorubicin (Dox) is a potent anticancer agent, but its associated organ toxicity, including nephrotoxicity, restricts clinical applications. Dapagliflozin (DAPA), a sodium-glucose cotransporter-2 inhibitor, has been shown to slow the progression of kidney disease in patients with and without diabetes. However, the effect of DAPA to counteract Dox-induced nephrotoxicity remains uncertain. Therefore, in this study, we aimed to elucidate the effects of DAPA in mitigating Dox-induced nephrotoxicity. We analyzed the Taiwan National Health Insurance Database to evaluate the incidence of renal failure among breast cancer patients receiving Dox treatment compared to those without. After adjusting for age and comorbidities, we found that the risk of renal failure was significantly higher in Dox-treated patients (incidence rate ratio, 2.45; confidence interval, 1.41-4.26; p = 0.0014). In a parallel study, we orally administered DAPA to Sprague-Dawley rats for 6 weeks, followed by Dox for 4 weeks. DAPA ameliorated Dox-induced glomerular atrophy, renal fibrosis, and dysfunction. Furthermore, DAPA effectively suppressed Dox-induced apoptosis and reactive oxygen species production. On a cellular level, DAPA in HK-2 cells mitigated Dox-mediated suppression of the endothelial NOS pathway and reduced Dox-induced activities of reactive oxygen species and apoptosis-associated proteins. DAPA improved Dox-induced apoptosis and renal dysfunction, suggesting its potential utility in preventing nephrotoxicity in patients with cancer undergoing Dox treatment.

NO Addition during Gas Oxygenation Reduces Liver and Kidney Injury during Prolonged Cardiopulmonary Bypass

Objective. To evaluate the effect of NO added to the sweep gas of the oxygenator during cardiopulmonary bypass (CPB) on the liver and kidneys in pigs. Methods. An experiment was carried out on 10 pigs undergoing cardiac surgery using CPB. NO was added to the sweep gas of the oxygenator at a concentration of 100 ppm for the animals in the experimental group (CPB-NO, n = 5). Animals in the control group (CPB-contr, n = 5) did not receive NO in the sweep gas of the oxygenator. The CPB lasted 4 h, followed by postoperative monitoring for 12 h. To assess the injury to the liver and kidneys, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, creatinine, and neutrophil gelatinase-associated lipocalin (NGAL) were determined initially, at weaning from the CPB, and 6 and 12 h after weaning from the CPB. The glomerular filtration rate (GFR) was evaluated initially, at weaning from the CPB, and 6 and 12 h after weaning from the CPB. A pathomorphological study of the liver and kidneys was performed using semiquantitative morphometry. Results. The long four-hour period of CPB deliberately used in our experiment caused liver and kidney injury. In the CPB-contr group, an increase in the ALT concentration was found: 43 (34; 44) U/L at baseline to 82 (53; 99) U/L 12 h after CPB, p < 0.05. The AST concentration in the CPB-contr group increased from 25 (17; 26) U/L at baseline to 269 (164; 376) U/L 12 h after CPB, p < 0.05. We found no significant increase in the ALT and AST concentrations in the CPB-NO group. There were no significant differences in ALT and AST concentrations between the CPB-NO and CPB-contr groups at all the study time-points. In the CPB-contr group, an increase in the creatinine level was found from 131 (129; 133) µmol/L at baseline to 273 (241; 306) µmol/L 12 h after CPB, p < 0.05. We found no significant increase in creatinine level in the CPB-NO group. Creatinine levels in the CPB-NO group were significantly lower than in the CPB-contr group 12 h after weaning from CPB: 183 (168; 196) vs. 273 (241; 306) µmol/L; p = 0.008. The GFR in the CPB-NO group was significantly higher than in the CPB-contr group 6 h after weaning from CPB: 78.9 (77.8; 82.3) vs. 67.9 (62.3; 69.2) mL/min; p = 0.016. GFR was significantly higher in the CPB-NO group than in the CPB-contr group 12 h after weaning from CPB: 67.7 (65.5; 68.0) vs. 50.3 (48.7; 54.9) mL/min; p = 0.032. We found no significant differences between the study groups in the level of NGAL. We found several differences between the groups in the pathomorphological study. Conclusions. NO added to the sweep gas of the oxygenator reduces creatinine levels and increases GFR during prolonged CPB injury. Further research is required.

Biochemical Changes in Cardiopulmonary Bypass in Cardiac Surgery: New Insights

Patients undergoing coronary revascularization with extracorporeal circulation or cardiopulmonary bypass (CPB) may develop several biochemical changes in the microcirculation that lead to a systemic inflammatory response. Surgical incision, post-CPB reperfusion injury and blood contact with non-endothelial membranes can activate inflammatory signaling pathways that lead to the production and activation of inflammatory cells, with cytokine production and oxidative stress. This inflammatory storm can cause damage to vital organs, especially the heart, and thus lead to complications in the postoperative period. In addition to the organic pathophysiology during and after the period of exposure to extracorporeal circulation, this review addresses new perspectives for intraoperative treatment and management that may lead to a reduction in this inflammatory storm and thereby improve the prognosis and possibly reduce the mortality of these patients.

The predictive values of monocyte-lymphocyte ratio in postoperative acute kidney injury and prognosis of patients with Stanford type A aortic dissection

Objectives

Postoperative acute kidney injury (pAKI) is a serious complication of Stanford type A aortic dissection (TAAD) surgery, which is significantly associated with the inflammatory response. This study aimed to explore the relationship between blood count-derived inflammatory markers (BCDIMs) and pAKI and to construct a predictive model for pAKI.

Methods

Patients who underwent TAAD surgery were obtained from our center and the Medical Information Mart for Intensive Care (MIMIC)-IV database. The differences in preoperative BCDIMs and clinical outcomes of patients with and without pAKI were analyzed. Logistic regression was used to construct predictive models based on preoperative BCDIMs or white cell counts (WCCs). The performance of the BCDIMs and WCCs models was evaluated and compared using the receiver operating characteristic (ROC) curve, area under the ROC curve (AUC), Hosmer-Lemeshow test, calibration plot, net reclassification index (NRI), integrated discrimination improvement index (IDI), and decision curve analysis (DCA). The Kaplan-Meier curves were applied to compare the survival rate between different groups.

Results

The overall incidence of pAKI in patients who underwent TAAD surgery from our center was 48.63% (124/255). The presence of pAKI was associated with longer ventilation time, higher incidence of cerebral complications and postoperative hepatic dysfunction, and higher in-hospital mortality. The results of the logistic regression indicated that the monocyte-lymphocyte ratio (MLR) was an independent risk factor for pAKI. The BCDIMs model had good discriminating ability, predictive ability, and clinical utility. In addition, the performance of the BCDIMs model was significantly better than that of the WCCs model. Analysis of data from the MIMIC-IV database validated that MLR was an independent risk factor for pAKI and had predictive value for pAKI. Finally, data from the MIMIC-IV database demonstrated that patients with a high MLR had a significantly poor 28-day survival rate when compared to patients with a low MLR.

Conclusion

Our study suggested that the MLR is an independent risk factor for pAKI. A predictive model based on BCDIMs had good discriminating ability, predictive ability, and clinical utility. Moreover, the performance of the BCDIMs model was significantly better than that of the WCCs model. Finally, a high MLR was significantly associated with poor short-term survival of patients who underwent TAAD surgery.

Nitric Oxide in Cardiac Surgery: A Review Article

Perioperative organ injury remains a medical, social and economic problem in cardiac surgery. Patients with postoperative organ dysfunction have increases in morbidity, length of stay, long-term mortality, treatment costs and rehabilitation time. Currently, there are no pharmaceutical technologies or non-pharmacological interventions that can mitigate the continuum of multiple organ dysfunction and improve the outcomes of cardiac surgery. It is essential to identify agents that trigger or mediate an organ-protective phenotype during cardiac surgery. The authors highlight nitric oxide (NO) ability to act as an agent for perioperative protection of organs and tissues, especially in the heart-kidney axis. NO has been delivered in clinical practice at an acceptable cost, and the side effects of its use are known, predictable, reversible and relatively rare. This review presents basic data, physiological research and literature on the clinical application of NO in cardiac surgery. Results support the use of NO as a safe and promising approach in perioperative patient management. Further clinical research is required to define the role of NO as an adjunct therapy that can improve outcomes in cardiac surgery. Clinicians also have to identify cohorts of responders for perioperative NO therapy and the optimal modes for this technology.

Therapeutic Effects of Inhaled Nitric Oxide Therapy in COVID-19 Patients

The global COVID-19 pandemic has become the largest public health challenge of recent years. The incidence of COVID-19-related acute hypoxemic respiratory failure (AHRF) occurs in up to 15% of hospitalized patients. Antiviral drugs currently available to clinicians have little to no effect on mortality, length of in-hospital stay, the need for mechanical ventilation, or long-term effects. Inhaled nitric oxide (iNO) administration is a promising new non-standard approach to directly treat viral burden while enhancing oxygenation. Along with its putative antiviral affect in COVID-19 patients, iNO can reduce inflammatory cell-mediated lung injury by inhibiting neutrophil activation, lowering pulmonary vascular resistance and decreasing edema in the alveolar spaces, collectively enhancing ventilation/perfusion matching. This narrative review article presents recent literature on the iNO therapy use for COVID-19 patients. The authors suggest that early administration of the iNO therapy may be a safe and promising approach for the treatment of COVID-19 patients. The authors also discuss unconventional approaches to treatment, continuous versus intermittent high-dose iNO therapy, timing of initiation of therapy (early versus late), and novel delivery systems. Future laboratory and clinical research is required to define the role of iNO as an adjunct therapy against bacterial, viral, and fungal infections.