Potential Mechanisms for Organoprotective Effects of Exogenous Nitric Oxide in an Experimental Study.

Performing cardiac surgery under cardiopulmonary bypass (CPB) and circulatory arrest (CA) provokes the development of complications caused by tissue metabolism, microcirculatory disorders, and endogenous nitric oxide (NO) deficiency. This study aimed to investigate the potential mechanisms for systemic organoprotective effects of exogenous NO during CPB and CA based on the assessment of dynamic changes in glycocalyx degradation markers, deformation properties of erythrocytes, and tissue metabolism in the experiment. A single-center prospective randomized controlled study was conducted on sheep, n = 24, comprising four groups of six in each. In two groups, NO was delivered at a dose of 80 ppm during CPB ("CPB + NO" group) or CPB and CA ("CPB + CA + NO"). In the "CPB" and "CPB + CA" groups, NO supply was not carried out. NO therapy prevented the deterioration of erythrocyte deformability. It was associated with improved tissue metabolism, lower lactate levels, and higher ATP levels in myocardial and lung tissues. The degree of glycocalyx degradation and endothelial dysfunction, assessed by the concentration of heparan sulfate proteoglycan and asymmetric dimethylarginine, did not change when exogenous NO was supplied. Intraoperative delivery of NO provides systemic organoprotection, which results in reducing the damaging effects of CPB on erythrocyte deformability and maintaining normal functioning of tissue metabolism.

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.

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

OBJECTIVE: Acute kidney injury (AKI) is a serious complication of cardiac surgery with cardiopulmonary bypass (CPB). The aim of this study was to evaluate the effects of nitric oxide (NO) supplementation to the CPB circuit on the development of cardiac surgery-associated AKI. METHODS: This prospective randomized controlled study included 96 patients with moderate risk of renal complications who underwent elective cardiac surgery with CPB. The study protocol was registered at ClinicalTrials.gov (identifier NCT03527381). Patients were randomly allocated to either NO supplementation to the CPB bypass circuit (NO treatment group; n = 48) or usual care (control group; n = 48). In the NO treatment group, 40-ppm NO was administered during the entire CPB period. The primary outcome was the incidence of AKI. RESULTS: NO treatment was associated with a significant decrease in AKI incidence (10 cases [20.8%] vs 20 cases [41.6%] in the control group; relative risk, 0.5; 95% confidence interval, 0.26-0.95; P = .023) and a higher median urine output during CPB (2.6 mL/kg/h [interquartile range (IQR), 2.1-5.08 mL/kg/h] vs 1.7 mL/kg/h [IQR, 0.80-2.50 mL/kg/h]; P = .0002). The median urinary neutrophil gelatinase-associated lipocalin level at 4 hours after surgery was significantly lower in the NO treatment group (1.12 ng/mL [IQR, 0.75-5.8 ng/mL] vs 4.62 ng/mL [IQR, 2.02-34.55 ng/mL]; P = .005). In the NO treatment group, concentrations of NO metabolites were significantly increased at 5 minutes postclamping, at 5 minutes after declamping, and at the end of the operation. Concentrations of proinflammatory and anti-inflammatory mediators and free plasma hemoglobin did not differ significantly between the 2 groups. CONCLUSIONS: NO administration in patients at moderate risk of renal complications undergoing elective cardiac surgery with CPB was associated with a lower incidence of AKI.

Effect of nitric oxide on postoperative acute kidney injury in patients who underwent cardiopulmonary bypass: a systematic review and meta-analysis with trial sequential analysis.

BACKGROUND: The effect of nitric oxide (NO) on renal function is controversial in critical illness. We performed a systematic meta-analysis and trial sequential analysis to determine the effect of NO gas on renal function and other clinical outcomes in patients requiring cardiopulmonary bypass (CPB). The primary outcome was the relative risk (RR) of acute kidney injury (AKI), irrespective of the AKI stage. The secondary outcome was the mean difference (MD) in the length of ICU and hospital stay, the RR of postoperative hemorrhage, and the MD in levels of methemoglobin. Trial sequential analysis (TSA) was performed for the primary outcome. RESULTS: 54 trials were assessed for eligibility and 5 studies (579 patients) were eligible for meta-analysis. NO was associated with reduced risk of AKI (RR 0.76, 95% confidential interval [CI], 0.62 to 0.93, I2 = 0%). In the subgroup analysis by NO initiation timing, NO did not decrease the risk of AKI when started at the end of CPB (RR 1.20, 95% CI 0.52-2.78, I2 = 0%). However, NO did significantly reduce the risk of AKI when started from the beginning of CPB (RR 0.71, 95% CI 0.54-0.94, I2 = 10%). We conducted TSA based on three trials (400 patients) using KDIGO criteria and with low risk of bias. TSA indicated a CI of 0.50-1.02 and an optimal information size of 589 patients, suggesting a lack of definitive conclusion. Furthermore, NO does not affect the length of ICU and hospital stay or the risk of postoperative hemorrhage. NO slightly increased the level of methemoglobin at the end of CPB (MD 0.52%, 95% CI 0.27-0.78%, I2 = 90%), but it was clinically negligible. CONCLUSIONS: NO appeared to reduce the risk of postoperative AKI in patients undergoing CPB. Additional studies are required to ascertain the finding and further determine the dosage, timing and duration of NO administration.

Nitric oxide provides myocardial protection when added to the cardiopulmonary bypass circuit during cardiac surgery: Randomized trial.

OBJECTIVES: The aim of this pilot study was to elucidate the effects of exogenous nitric oxide (NO) supply to the extracorporeal circulation circuit for cardioprotection against ischemia-reperfusion injury during coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). METHODS: A total of 60 patients with coronary artery disease scheduled for CABG with CPB were enrolled in a prospective randomized study. Patients were allocated randomly to receive treatment according to standard or modified CPB protocol where 40-ppm NO was added to the CPB circuit during cardiac surgery. The primary endpoint was the measurement of cardiac troponin I (cTnI). The secondary end points consisted in the measurements of creatine kinase-muscle/brain fraction (CK-MB) and vasoactive inotropic score (VIS). RESULTS: NO delivered into the CPB circuit had a cardioprotective effect. The level of cTnI was significantly lower in NO-treated group compared with the control group 6 hours after surgery: 1.79 ± 0.39 ng/mL versus 2.41 ± 0.55 ng/mL, respectively (P = .001). The CK-MB value was significantly lower in NO-treated group compared with the control group 24 hours after surgery: 47.69 ± 8.08 U/L versus 62.25 ± 9.78 U/L, respectively (P = .001); and the VIS was significantly lower in the NO-treated group 6 hours after the intervention. CONCLUSIONS: NO supply to the CPB circuit during CABG exerted a cardioprotective effect and was associated with lower levels of VIS and cardiospecific blood markers cTnI and CK-MB.