Nitric Oxide in Cardiac Surgery: A Review Article

High-dose inhaled NO for the prevention of nosocomial pneumonia after cardiac surgery under cardiopulmonary bypass: A proof-of-concept prospective randomised study

OBJECTIVE

This study aimed to assess the safety and potential efficacy of high-dose inhaled nitric oxide therapy for the prevention of postoperative pneumonia in cardiac surgery patients.

METHODS

A prospective randomised controlled pilot study included 74 patients with moderate risk of postoperative pneumonia after elective cardiac surgery under cardiopulmonary bypass. Patients were randomised into two groups. The main group (NO-group) (n = 37) received inhaled nitric oxide at a dose of 200 ppm for 30 minutes 2 times a day for 5 days or until pneumonia developed. The control group received conventional postoperative care (n = 37). The primary endpoint was the incidence of postoperative pneumonia during in-hospital stay.

RESULTS

Preventive nitric oxide inhalations were associated with a reduced incidence of postoperative nosocomial pneumonia (2 (5.4%) cases in the main group (NO-group) vs. 9 (24.3%) cases in the control group, p = 0.046; OR = 0.178, 95% CI = 0.036-0.89)). There was no decrease in either peak expiratory flow, or peak inspiratory flow in comparison with the preoperative values in the NO-group. Inhaled nitric oxide therapy is safe. It did not lead to an increase in the incidence of acute kidney injury.

CONCLUSIONS

High-dose inhaled nitric oxide therapy is safe and effective for the prevention of postoperative nosocomial pneumonia in cardiac surgery.

2024 EACTS/EACTAIC/EBCP Guidelines on cardiopulmonary bypass in adult cardiac surgery

Clinical practice guidelines consolidate and evaluate all pertinent evidence on a specific topic available at the time of their formulation. The goal is to assist physicians in determining the most effective management strategies for patients with a particular condition. These guidelines assess the impact on patient outcomes and weigh the risk-benefit ratio of various diagnostic or therapeutic approaches. While not a replacement for textbooks, they provide supplementary information on topics relevant to current clinical practice and become an essential tool to support the decisions made by specialists in daily practice. Nonetheless, it is crucial to understand that these recommendations are intended to guide, not dictate, clinical practice, and should be adapted to each patient's unique needs. Clinical situations vary, presenting a diverse array of variables and circumstances. Thus, the guidelines are meant to inform, not replace, the clinical judgement of healthcare professionals, grounded in their professional knowledge, experience and comprehension of each patient's specific context. Moreover, these guidelines are not considered legally binding; the legal duties of healthcare professionals are defined by prevailing laws and regulations, and adherence to these guidelines does not modify such responsibilities. The European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Cardiothoracic Anaesthesiology and Intensive Care (EACTAIC) and the European Board of Cardiovascular Perfusion (EBCP) constituted a task force of professionals specializing in cardiopulmonary bypass (CPB) management. To ensure transparency and integrity, all task force members involved in the development and review of these guidelines submitted conflict of interest declarations, which were compiled into a single document available on the EACTS website (https://www.eacts.org/resources/clinical-guidelines). Any alterations to these declarations during the development process were promptly reported to the EACTS, EACTAIC and EBCP. Funding for this task force was provided exclusively by the EACTS, EACTAIC and EBCP, without involvement from the healthcare industry or other entities. Following this collaborative endeavour, the governing bodies of EACTS, EACTAIC and EBCP oversaw the formulation, refinement, and endorsement of these extensively revised guidelines. An external panel of experts thoroughly reviewed the initial draft, and their input guided subsequent amendments. After this detailed revision process, the final document was ratified by all task force experts and the leadership of the EACTS, EACTAIC and EBCP, enabling its publication in the European Journal of Cardio-Thoracic Surgery, the British Journal of Anaesthesia and Interdisciplinary CardioVascular and Thoracic Surgery. Endorsed by the EACTS, EACTAIC and EBCP, these guidelines represent the official standpoint on this subject. They demonstrate a dedication to continual enhancement, with routine updates planned to ensure that the guidelines remain current and valuable in the ever-progressing arena of clinical practice.

Prolonged Cardiopulmonary Bypass Time-Induced Endothelial Dysfunction via Glypican-1 Shedding, Inflammation, and Matrix Metalloproteinase 9 in Patients Undergoing Cardiac Surgery

OBJECTIVES

A prolonged cardiopulmonary bypass (CPB) time of over 180 min is linked to poorer outcomes and higher mortality in cardiac surgery. This study examines how glypican-1 shedding, matrix metallopeptidase 9 (MMP9), and the pro-inflammatory cytokine IL-1β may contribute to endothelial dysfunction in patients undergoing on-pump surgery with an extended CPB.

METHODS

Fifty-one patients undergoing cardiac surgical procedures were divided into two groups based on the intraoperative CPB duration: (i) normal CPB (<180 min, n = 23) and (ii) prolonged CPB (>180 min, n = 28). The preoperative, intraoperative, and postoperative plasma levels of glypican-1, MMP9, and IL-1β were measured.

RESULTS

Before surgery, the plasma levels of glypican-1, MMP9, and IL-1β were comparable between the normal CPB and the prolonged CPB groups. However, after the end of the CPB, all three markers showed significant elevation in the prolonged CPB group compared to the normal CPB group. Significant correlations were observed between the intraoperative and postoperative levels of MMP9, IL-1β, and glypican-1. A strong positive correlation was also observed between the intraoperative and postoperative levels of glypican-1 and the duration of the CPB.

CONCLUSIONS

A prolonged CPB triggers a systemic inflammatory response and activates MMP9, leading to glypican-1 shedding and endothelial dysfunction.

Effect of nitric oxide delivery via cardiopulmonary bypass circuit on postoperative oxygenation in adults undergoing cardiac surgery (NOCARD trial): a randomised controlled trial

BACKGROUND

Cardiac surgery involving cardiopulmonary bypass induces a significant systemic inflammatory response, contributing to various postoperative complications, including pulmonary dysfunction, myocardial and kidney injuries.

OBJECTIVE

To investigate the effect of Nitric Oxide delivery via the cardiopulmonary bypass circuit on various postoperative outcomes.

DESIGN

A prospective, single-centre, double-blinded, randomised controlled trial.

SETTING

Rabin Medical Centre, Beilinson Hospital, Israel.

PATIENTS

Adult patients scheduled for elective cardiac surgery were randomly allocated to one of the study groups.

INTERVENTIONS

For the treatment group, 40 ppm of nitric oxide was delivered via the cardiopulmonary bypass circuit. For the control group, nitric oxide was not delivered.

OUTCOME MEASURES

The primary outcome was the incidence of hypoxaemia, defined as a p a O2 /FiO 2 ratio less than 300 within 24 h postoperatively. The secondary outcomes were the incidences of low cardiac output syndrome and acute kidney injury within 72 h postoperatively.

RESULTS

Ninety-eight patients were included in the final analysis, with 47 patients allocated to the control group and 51 to the Nitric Oxide group. The Nitric Oxide group exhibited significantly lower hypoxaemia rates at admission to the cardiothoracic intensive care unit (47.1 vs. 68.1%), P  = 0.043. This effect, however, varied in patients with or without baseline hypoxaemia. Patients with baseline hypoxaemia who received nitric oxide exhibited significantly lower hypoxaemia rates (61.1 vs. 93.8%), P  = 0.042, and higher p a O2 /FiO 2 ratios at all time points, F (1,30) = 6.08, P  = 0.019. Conversely, this benefit was not observed in patients without baseline hypoxaemia. No significant differences were observed in the incidence of low cardiac output syndrome or acute kidney injury. No substantial safety concerns were noted, and toxic methaemoglobin levels were not observed.

CONCLUSIONS

Patients with baseline hypoxaemia undergoing cardiac surgery and receiving nitric oxide exhibited lower hypoxaemia rates and higher p a O2 /FiO 2 ratios. No significant differences were found regarding postoperative pulmonary complications and overall outcomes.

TRIAL REGISTRATION

NCT04807413.

The Nephroprotective Effect of Nitric Oxide during Extracorporeal Circulation: An Experimental Study

This study aims to determine the effectiveness of administering 80 ppm nitric oxide in reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental perfusion. Twenty-four sheep were randomized into four groups: two groups received 80 ppm NO conditioning with 90 min of cardiopulmonary bypass (CPB + NO) or 90 min of CPB and hypothermic circulatory arrest (CPB + CA + NO), while two groups received sham protocols (CPB and CPB + CA). Kidney injury was assessed using laboratory (neutrophil gelatinase-associated lipocalin, an acute kidney injury biomarker) and morphological methods (morphometric histological changes in kidney biopsy specimens). A kidney biopsy was performed 60 min after weaning from mechanical perfusion. NO did not increase the concentrations of inhaled NO2 and methemoglobin significantly. The NO-conditioning groups showed less severe kidney injury and mitochondrial dysfunction, with statistical significance in the CPB + NO group and reduced tumor necrosis factor-α expression as a trigger of apoptosis and necroptosis in renal tissue in the CPB + CA + NO group compared to the CPB + CA group. The severity of mitochondrial dysfunction in renal tissue was insignificantly lower in the NO-conditioning groups. We conclude that NO administration is safe and effective at reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental CPB.

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.

Inhaled Nitric Oxide ReDuce postoperatIve pulmoNAry complicaTions in patiEnts with recent COVID-19 infection (INORDINATE): protocol for a randomised controlled trial

BACKGROUND

A history of SARS-CoV-2 infection has been reported to be associated with an increased risk of postoperative pulmonary complications (PPCs). Even mild PPCs can elevate the rates of early postoperative mortality, intensive care unit (ICU) admission and prolong the length of ICU and/or hospital stays. Consequently, it is crucial to develop perioperative management strategies that can mitigate these increased risks in surgical patients who have recently been infected with SARS-CoV-2. Accumulating evidence suggests that nitric oxide (NO) inhalation might be effective in treating COVID-19. NO functions in COVID-19 by promoting vasodilation, anticoagulation, anti-inflammatory and antiviral effects. Therefore, our study hypothesises that the perioperative use of NO can effectively reduce PPCs in patients with recent SARS-CoV-2 infection.

METHOD AND ANALYSIS

A prospective, double-blind, single-centre, randomised controlled trial is proposed. The trial aims to include participants who are planning to undergo surgery with general anaesthesia and have been recently infected with SARS-CoV-2 (within 7 weeks). Stratified allocation of eligible patients will be performed at a 1:1 ratio based on the predicted risk of PPCs using the Assess Respiratory Risk in Surgical Patients in Catalonia risk index and the time interval between infection and surgery.The primary outcome of the study will be the presence of PPCs within the first 7 days following surgery, including respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm and aspiration pneumonitis. The primary outcome will be reported as counts (percentage) and will be compared using a two-proportion χ2 test. The common effect across all primary components will be estimated using a multiple generalised linear model.

ETHICS AND DISSEMINATION

The trial is approved by the Institutional Review Board of Xijing Hospital (KY20232058-F1). The findings, including positive, negative and inconclusive results, will be published in scientific journals with peer-review processes.

TRIAL REGISTRATION NUMBER

NCT05721144.

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.