Clinical indication for use and outcomes after inhaled nitric oxide therapy

Right Heart Failure in the Intensive Care Unit: Etiology, Pathogenesis, Diagnosis, and Treatment

Right heart (RH) failure carries a high rate of morbidity and mortality. Patients who present with RH failure often exhibit complex aberrant cardio-pulmonary physiology with varying presentations. The treatment of RH failure almost always requires care and management from an intensivist. Treatment options for RH failure patients continue to evolve rapidly with multiple options available, including different pharmacotherapies and mechanical circulatory support devices that target various components of the RH circulatory system. An understanding of the normal RH circulatory physiology, treatment, and support options for the RH failure patients is necessary for all intensivists to improve outcomes. The purpose of this review is to provide clinical guidance on the diagnosis and management of RH failure within the intensive care unit setting, and to highlight the different pathophysiological manifestations of RH failure, its hemodynamics, and treatment options available at the disposal of the intensivist.

Clinical Applications for Gasotransmitters in the Cardiovascular System: Are We There Yet?

Ischemia is the underlying mechanism in a wide variety of acute and persistent pathologies. As such, understanding the fine intracellular events occurring during (and after) the restriction of blood supply is pivotal to improving the outcomes in clinical settings. Among others, gaseous signaling molecules constitutively produced by mammalian cells (gasotransmitters) have been shown to be of potential interest for clinical treatment of ischemia/reperfusion injury. Nitric oxide (NO and its sibling, HNO), hydrogen sulfide (H2S), and carbon monoxide (CO) have long been proven to be cytoprotective in basic science experiments, and they are now awaiting confirmation with clinical trials. The aim of this work is to review the literature and the clinical trials database to address the state of development of potential therapeutic applications for NO, H2S, and CO and the clinical scenarios where they are more promising.

Haemodynamic effects of inhaled nitric oxide in acute myocardial infarction complicated by right heart failure under ECPELLA support: case report

Background

Recently, mechanical support obtained with the combination of venoarterial extracorporeal membrane oxygenation (VA-ECMO) and an Impella device, together referred to as ECPELLA, has been shown to be effective for acute myocardial infarction with cardiogenic shock. However, methods for withdrawing VA-ECMO in acute myocardial infarction cases complicated by right ventricular dysfunction are yet to be established. Here, we report the effective use of inhaled nitric oxide during the weaning of VA-ECMO from the ECPELLA management of a patient with acute myocardial infarction with cardiogenic shock.

Case summary

An 81-year-old man with an acute extensive anterior wall myocardial infarction with cardiogenic shock was supported with ECPELLA to improve his haemodynamics. During ECPELLA, the Impella device could not maintain sufficient flow. Echocardiography revealed a small left ventricle and an enlarged right ventricle, indicating acute right heart failure. Inhaled nitric oxide was initiated to reduce right ventricle afterload, which decreased pulmonary artery pressure from 34/20 to 27/13 mmHg, improved right and left ventricle sizes, and stabilized the Impella support. Afterward, VA-ECMO could be withdrawn because the Impella alone was sufficient for haemodynamic support.

Discussion

Inhaled nitric oxide improved right ventricle performance in a patient with severe myocardial infarction with right heart failure supported by ECPELLA. Thus, we suggest that inhaled nitric oxide facilitates the weaning of VA-ECMO from patients with refractory right ventricular dysfunction who are supported by ECPELLA.

Heart Failure After Right Ventricular Myocardial Infarction

PURPOSE OF REVIEW

Heart failure (HF) after right ventricular myocardial infarction (RVMI) is common and complicates its clinical course. This review aims to provide a current overview on the characteristic features of RV failure with focus on acute management.

RECENT FINDINGS

While HF after RVMI is classically seen after acute proximal right coronary artery occlusion, RV dysfunction may also occur after larger infarctions in the left coronary artery. Because of its different anatomy and physiology, the RV appears to be more resistant to permanent infarction compared to the LV with greater potential for recovery of ischemic myocardium. Hypotension and elevated jugular pressure in the presence of clear lung fields are hallmark signs of RV failure and should prompt confirmation by echocardiography. Management decisions are still mainly based on small studies and extrapolation of findings from LV failure. Early revascularization improves short- and long-term outcomes. Acute management should further focus on optimization of preload and afterload, maintenance of sufficient perfusion pressures, and prompt management of arrhythmias and concomitant LV failure, if present. In case of cardiogenic shock, use of vasopressors and/or inotropes should be considered along with timely use of mechanical circulatory support (MCS) in eligible patients. HF after RVMI is still a marker of worse outcome in acute coronary syndrome. Prompt revascularization, careful medical therapy with attention to the special physiology of the RV, and selected use of MCS provide the RV the time it needs to recover from the ischemic insult.

Current status of inhaled nitric oxide therapy for lung transplantation in Japan: a nationwide survey

OBJECTIVES

Currently, inhaled nitric oxide (NO) therapy for lung transplantation is not covered by public health insurance in Japan. In this study, we evaluated the perioperative use and safety of inhaled NO therapy for lung transplantation.

METHODS

Data regarding the duration of treatment and adverse events of inhaled NO therapy were collected for all lung transplantations performed from January 1, 2015, to December 31, 2019, at nine lung transplant facilities in Japan.

RESULTS

During the study period, lung transplants were performed in 357 patients, among whom inhaled NO therapy was administered to 349 patients (98%). The median initial and median maximum inhaled NO doses were 10 and 20 ppm, respectively. Inhaled NO therapy was introduced during surgery and continued postoperatively in 313 patients (90%) for a median of 4 days. Significant improvements in oxygenation and decreases in pulmonary arterial pressure were observed in patients receiving inhaled NO therapy. Side effects of inhaled NO therapy, such as methemoglobinemia, were observed in 15 patients (4%), with a significant incidence in patients aged < 18 years.

CONCLUSIONS

Inhaled NO therapy was performed in almost all patients who underwent lung transplantation in Japan and showed reasonable efficacy. Therefore, public health insurance coverage for inhaled NO therapy during lung transplantation is recommended.

Inhaled pulmonary vasodilators: a narrative review

Pulmonary hypertension (PH) is a severe disease that affects people of all ages. It can occur as an idiopathic disorder at birth or as part of a variety of cardiovascular and pulmonary disorders. Inhaled pulmonary vasodilators (IPV) can reduce pulmonary vascular resistance (PVR) and improve RV function with minimal systemic effects. IPV includes inhaled nitric oxide (iNO), inhaled aerosolized prostacyclin, or analogs, including epoprostenol, iloprost, treprostinil, and other vasodilators. In addition to pulmonary vasodilating effects, IPV can also be used to improve oxygenation, reduce inflammation, and protect cell. Off-label use of IPV is common in daily clinical practice. However, evidence supporting the inhalational administration of these medications is limited, inconclusive, and controversial regarding their safety and efficacy. We conducted a search for relevant papers published up to May 2020 in four databases: PubMed, Google Scholar, EMBASE and Web of Science. This review demonstrates that the clinical using and updated evidence of IPV. iNO is widely used in neonates, pediatrics, and adults with different cardiopulmonary diseases. The limitations of iNO include high cost, flat dose-response, risk of significant rebound PH after withdrawal, and the requirement of complex technology for monitoring. The literature suggests that inhaled aerosolized epoprostenol, iloprost, treprostinil and others such as milrinone and levosimendan may be similar to iNO. More research of IPV is needed to determine acceptable inclusion criteria, long-term outcomes, and management strategies including time, dose, and duration.

Newer approaches and novel drugs for inhalational therapy for pulmonary arterial hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by remodeling of small pulmonary arteries leading to increased pulmonary arterial pressure. Existing treatments acts to normalize vascular tone via three signaling pathways: the prostacyclin, the endothelin-1, and the nitric oxide. Although over the past 20 years, there has been considerable progress in terms of treatments for PAH, the disease still remains incurable with a disappointing prognosis.Areas covered: This review summarizes the pathophysiology of PAH, the advantages and disadvantages of the inhalation route, and assess the relative advantages various inhaled therapies for PAH. The recent studies concerning the development of controlled-release drug delivery systems loaded with available anti-PAH drugs have also been summarized.Expert opinion: The main obstacles of current pharmacotherapies of PAH are their short half-life, stability, and formulations, resulting in reducing the efficacy and increasing systemic side effects and unknown pathogenesis of PAH. The pulmonary route has been proposed for delivering anti-PAH drugs to overcome the shortcomings. However, the application of approved inhaled anti-PAH drugs is limited. Inhalational delivery of controlled-release nanoformulations can overcome these restrictions. Extensive studies are required to develop safe and effective drug delivery systems for PAH patients.

Inhaled Nitric Oxide as an Adjunct to Thrombolytic Therapy in a Patient with Submassive Pulmonary Embolism and Severe Hypoxemia

Introduction

Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator with limited indications in adults. We present a patient with hypoxemia and right ventricular dysfunction due to submassive acute pulmonary emboli where iNO was used as a bridge to thrombolysis.

Case

A 29-year-old male was admitted to the intensive care unit (ICU) for alcohol intoxication complicated with aspiration pneumonia and acute respiratory failure requiring mechanical ventilation. His medical history included morbid obesity (BMI 43) and alcohol dependence syndrome. Nine days after admission, he developed severe acute hypoxia and tachycardia with arterial oxygen tension (PaO2) of 52 mmHg requiring a positive end-expiratory pressure (PEEP) of 14 cmH2O and fraction of inspired oxygen (FiO2) of 1. Chest computed tomography (CT) revealed a large embolus in the right main pulmonary artery and transthoracic echocardiogram (TTE) reported new right ventricular dilatation with decreased right ventricular function. Due to the severe hypoxemia, he was started on iNO via the breathing circuit of the ventilator at a concentration of 20 parts per million (ppm) with steady improvement in oxygenation after 1 hour with a PaO2 of 81 mmHg on the same ventilator setting. The patient was given thrombolysis with alteplase and the iNO was slowly tapered off during the subsequent four days with concomitant successful tapering of PEEP to 8 cmH2O and FiO2 of 0.45.

Conclusion

Inhaled NO has been used to improve ventilation-perfusion matching and also to reduce pulmonary vascular resistance (PVR). Its effects on PVR may be useful in the setting of acute pulmonary emboli where vascular obstruction and vasoconstriction contribute to increased pulmonary arterial pressure and PVR which can present as acute right heart failure. We suggest that iNO, if available, could be considered in those patients with acute pulmonary emboli associated with significant hypoxemia as an adjunctive therapy or bridge to thrombolysis or thrombectomy.

Practice Variation, Costs and Outcomes Associated with the Use of Inhaled Nitric Oxide in Pediatric Heart Transplant Recipients

Right ventricular (RV) failure is a potentially fatal complication following heart transplantation (HTx). Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator that is used to decrease pulmonary vascular resistance immediately post-HTx to reduce the risk of RV failure. The aim of this study was to describe utilization patterns, costs, and outcomes associated with post-transplant iNO use in children. All pediatric HTx recipients (2002-2016) were identified from a unique linked PHIS/SRTR dataset. Post-HTx iNO use was determined based on hospital billing data. Utilization patterns and associated costs were described. The association of iNO support with post-HTx survival was assessed using the Kaplan-Meier method and a multivariable Cox proportional hazards model was used to adjust for risk factors. A total of 2833 pediatric HTx recipients from 28 centers were identified with 1057 (36.5%) receiving iNO post-HTx. Post-HTx iNO use showed significant increase overall (17.2-54.7%, p < 0.001) and wide variation among centers (9-100%, p < 0.001). Patients with congenital heart disease (aOR 1.4, 95% CI 1.2, 1.6), requiring mechanical ventilation at HTx (aOR 1.3, 95% CI 1.1, 1.6), and pre-transplant iNO (aOR 9.3, 95% CI 5.4, 16) were more likely to receive iNO post-HTx. The median daily cost of iNO was $2617 (IQR $1843-$3646). Patients who required > 5 days of iNO post-HTx demonstrated inferior 1-year post-HTx survival (p < 0.001) and iNO use > 5 days was independently associated with worse post-HTx survival (AHR 1.6, 95% CI 1.2, 2.1; p < 0.001). There is wide variation in iNO use among centers following pediatric HTx with use increasing over time despite significant incremental cost. Prolonged iNO use post-HTx is associated with worse survival, likely serving as a marker of residual illness severity. Further research is needed to define the populations that derive the greatest benefit from this costly therapy.

Diagnostic workup, etiologies and management of acute right ventricle failure : A state-of-the-art paper

INTRODUCTION

This is a state-of-the-art article of the diagnostic process, etiologies and management of acute right ventricular (RV) failure in critically ill patients. It is based on a large review of previously published articles in the field, as well as the expertise of the authors.

RESULTS

The authors propose the ten key points and directions for future research in the field. RV failure (RVF) is frequent in the ICU, magnified by the frequent need for positive pressure ventilation. While no universal definition of RVF is accepted, we propose that RVF may be defined as a state in which the right ventricle is unable to meet the demands for blood flow without excessive use of the Frank-Starling mechanism (i.e. increase in stroke volume associated with increased preload). Both echocardiography and hemodynamic monitoring play a central role in the evaluation of RVF in the ICU. Management of RVF includes treatment of the causes, respiratory optimization and hemodynamic support. The administration of fluids is potentially deleterious and unlikely to lead to improvement in cardiac output in the majority of cases. Vasopressors are needed in the setting of shock to restore the systemic pressure and avoid RV ischemia; inotropic drug or inodilator therapies may also be needed. In the most severe cases, recent mechanical circulatory support devices are proposed to unload the RV and improve organ perfusion CONCLUSION: RV function evaluation is key in the critically-ill patients for hemodynamic management, as fluid optimization, vasopressor strategy and respiratory support. RV failure may be diagnosed by the association of different devices and parameters, while echocardiography is crucial.

Nitric oxide: what's new to NO?

Nitric oxide (NO) is one of the critical components of the vasculature, regulating key signaling pathways in health. In macrovessels, NO functions to suppress cell inflammation as well as adhesion. In this way, it inhibits thrombosis and promotes blood flow. It also functions to limit vessel constriction and vessel wall remodeling. In microvessels and particularly capillaries, NO, along with growth factors, is important in promoting new vessel formation, a process termed angiogenesis. With age and cardiovascular disease, animal and human studies confirm that NO is dysregulated at multiple levels including decreased production, decreased tissue half-life, and decreased potency. NO has also been implicated in diseases that are related to neurotransmission and cancer although it is likely that these processes involve NO at higher concentrations and from nonvascular cell sources. Conversely, NO and drugs that directly or indirectly increase NO signaling have found clinical applications in both age-related diseases and in younger individuals. This focused review considers recently reported advances being made in the field of NO signaling regulation at several levels including enzymatic production, receptor function, interacting partners, localization of signaling, matrix-cellular and cell-to-cell cross talk, as well as the possible impact these newly described mechanisms have on health and disease.

Management of Crashing Patients with Pulmonary Hypertension

Critically ill patients with pulmonary hypertension (PH) often seem well, but they can decompensate dramatically in a short time. PH has several causes, classes, and complications; but the natural progression eventually leads to right ventricular failure, which can be extraordinarily difficult to manage. The purpose of this review is to discuss the causes, signs, and symptoms of PH as well as its management strategies and emergent complications. Treatment options are often limited, so it is imperative that the emergency department physician can recognize and manage these patients in a timely fashion.

Nitric oxide as a surgical adjuvant

Advances in surgical technology have allowed for previously unconsidered therapeutic interventions. However, the complexity and invasiveness of surgical procedures are not without adverse consequences. Nitric oxide's fundamental role in a host of physiological processes, including angiogenesis, wound and bone healing, thromboresistance, smooth muscle relaxation and inflammation makes it a significant player in accelerating wound healing and mitigating the inflammation of ischemia reperfusion injury common to surgical procedures. In addition, the therapeutic properties of NO have been harnessed for the prophylactic treatment of implant infection and graft failure. In this article, we will discuss the mechanism by which NO mediates these processes, and its perioperative translational applications.

Inhaled nitric oxide in cardiac surgery: Evidence or tradition?

Inhaled nitric oxide (iNO) therapy as a selective pulmonary vasodilator in cardiac surgery has been one of the most significant pharmacological advances in managing pulmonary hemodynamics and life threatening right ventricular dysfunction and failure. However, this remarkable story has experienced a roller-coaster ride with high hopes and nearly universal demonstration of physiological benefits but disappointing translation of these benefits to harder clinical outcomes. Most of our understanding on the iNO field in cardiac surgery stems from small observational or single centre randomised trials and even the very few multicentre trials fail to ascertain strong evidence base. As a consequence, there are only weak clinical practice guidelines on the field and only European expert opinion for the use of iNO in routine and more specialised cardiac surgery such as heart and lung transplantation and left ventricular assist device (LVAD) insertion. In this review the authors from a specialised cardiac centre in the UK with a very high volume of iNO usage provide detailed information on the early observations leading to the European expert recommendations and reflect on the nature and background of these recommendations. We also provide a summary of the progress in each of the cardiac subspecialties for the last decade and initial survey data on the views of senior anaesthetic and intensive care colleagues on these recommendations. We conclude that the combination of high price tag associated with iNO therapy and lack of substantial clinical evidence is not sustainable on the current field and we are risking loosing this promising therapy from our daily practice. Overcoming the status quo will not be easy as there is not much room for controlled trials in heart transplantation or in the current atmosphere of LVAD implantation. However, we call for international cooperation to conduct definite studies to determine the place of iNO therapy in lung transplantation and high risk mitral surgery. This will require new collaboration between the pharmaceutical companies, national grant agencies and the clinical community. Until these trials are realized we should gather multi-institutional experience from large retrospective studies and prospective data from a new international registry. We must step up international efforts if we wish to maintain the iNO modality in the armamentarium of hemodynamic tools for the perioperative management of our high risk cardiac surgical patients.

Predictors of right ventricular failure after left ventricular assist device implantation

Number of left ventricular assist device (LVAD) implantations increases every year, particularly LVADs for destination therapy (DT). Right ventricular failure (RVF) has been recognized as a serious complication of LVAD implantation. Reported incidence of RVF after LVAD ranges from 6% to 44%, varying mostly due to differences in RVF definition, different types of LVADs, and differences in patient populations included in studies. RVF complicating LVAD implantation is associated with worse postoperative mortality and morbidity including worse end-organ function, longer hospital length of stay, and lower success of bridge to transplant (BTT) therapy. Importance of RVF and its predictors in a setting of LVAD implantation has been recognized early, as evidenced by abundant number of attempts to identify independent risk factors and develop RVF predictor scores with a common purpose to improve patient selection and outcomes by recognizing potential need for biventricular assist device (BiVAD) at the time of LVAD implantation. The aim of this article is to review and summarize current body of knowledge on risk factors and prediction scores of RVF after LVAD implantation. Despite abundance of studies and proposed risk scores for RVF following LVAD, certain common limitations make their implementation and clinical usefulness questionable. Regardless, value of these studies lies in providing information on potential key predictors for RVF that can be taken into account in clinical decision making. Further investigation of current predictors and existing scores as well as new studies involving larger patient populations and more sophisticated statistical prediction models are necessary. Additionally, a short description of our empirical institutional approach to management of RVF following LVAD implantation is provided.

Preoperative Evaluation and Perioperative Management of Right Ventricular Failure After Left Ventricular Assist Device Implantation

Right ventricular (RV) failure continues to be a major cause of morbidity and mortality after left ventricular assist device (LVAD) implantation. Preoperative evaluation of RV function with a variety of clinical, laboratory, echocardiographic, and hemodynamic variables is essential to ensure appropriate patient selection for LVAD therapy but remains imperfect. Therefore, clinicians involved in the care of these patients need to be prepared to manage RV failure after LVAD placement. Perioperative management of RV failure after LVAD implantation requires minimization of intraoperative RV ischemia, maintenance of appropriate filling pressure, supportive therapy with pulmonary vasodilators and inotropes, and surgical interventions such as RV assist devices in select cases. This article reviews the incidence of RV failure with LVAD implantation, preoperative predictors of RV failure, and perioperative management strategies.

Pulmonary hypertension in critical care

PURPOSE OF REVIEW

To review the contemporary management of patients with pulmonary hypertension in critical care.

RECENT FINDINGS

The normal mean pulmonary artery pressure (mPAP) at rest is 14±3  mmHg and pulmonary hypertension is considered when mPAP is greater than or equal to 25  mmHg at rest. The classification of pulmonary hypertension has been redefined recently and updated in 2009 and could help to guide the management of patients with pulmonary hypertension in critical care. The management of pulmonary hypertension in ICU is based on expert opinion. Among the diagnostic and monitoring tools available, echocardiography provides useful information noninvasively, although pulmonary artery catheter must be used in case of complicated situations. Calcium sensitizers, a new class of inotrope, have inotropic effects and induce dilatation of the pulmonary, systemic, and coronary vasculature and thus could be useful in case of right ventricular failure (RVF), particularly in patients with acute respiratory distress syndrome (ARDS). By increasing the pulmonary vasodilator response to inhaled nitric oxide and preventing the rebound pulmonary vasoconstriction which occurs following cessation of nitric oxide breathing, selective type 5 isoform of phosphodiesterase inhibitors could be useful in critically ill patients.

SUMMARY

This article reviews recent and key findings on the management of pulmonary hypertension in critically ill patients.

Intensive care unit management of patients with severe pulmonary hypertension and right heart failure

Despite advances in medical therapies, pulmonary arterial hypertension (PAH) continues to cause significant morbidity and mortality. Although the right ventricle (RV) can adapt to an increase in afterload, progression of the pulmonary vasculopathy that characterizes PAH causes many patients to develop progressive right ventricular failure. Furthermore, acute right ventricular decompensation may develop from disorders that lead to either an acute increase in cardiac demand, such as sepsis, or to an increase in ventricular afterload, including interruptions in medical therapy, arrhythmia, or pulmonary embolism. The poor reserve of the right ventricle, RV ischemia, and adverse right ventricular influence on left ventricular filling may lead to a global reduction in oxygen delivery and multiorgan failure. There is a paucity of data to guide clinicians caring for acute right heart failure in PAH. Treatment recommendations are frequently based on animal models of acute right heart failure or case series in humans with other causes of pulmonary hypertension. Successful treatment often requires that invasive hemodynamics be used to monitor the effect of strategies that are based primarily on biological plausibility. Herein we have developed an approach based on the current understanding of RV failure in PAH and have attempted to develop a treatment paradigm based on physiological principles and available evidence.

Cardiogenic shock in ACS. Part 1: prediction, presentation and medical therapy

Ischemic cardiogenic shock is a complex, self-perpetuating pathological process that frequently causes death irrespective of medical therapy. Early definition of coronary anatomy is a pivotal step towards survival. Those destined to develop shock are likely to have three-vessel or left main stem disease with previously impaired left ventricular function. Early reperfusion of the occluded artery can limit infarct size, but ischemia-reperfusion injury or the 'no-reflow' phenomenon can preclude improvement in myocardial contractility. Emergence of shock depends upon the volume of ischemic myocardium, stroke volume, and peripheral vascular resistance. If cytokine release triggers the systemic inflammatory response, systemic vascular resistance falls and inadequate coronary perfusion pressure heralds the downward spiral. Survival depends on early recognition of shock, followed by aggressive targeted treatment of left, right, or biventricular failure. The goal is to prevent end-organ dysfunction and severe metabolic derangement by raising mean arterial pressure, which is achieved with inotropes and vasopressors, often at the expense of tachycardia, elevated myocardial oxygen consumption, and extended ischemia. The value of intra-aortic balloon counter-pulsation is now questioned in patients with advanced shock. When mean arterial pressure is <55 mmHg with serum lactate >11 mmol/l, death is likely and mechanical circulatory support becomes the only chance for survival.

'Safe' methaemoglobin concentrations are a mortality risk factor in patients receiving inhaled nitric oxide

Inhaled nitric oxide (iNO) can reduce pulmonary arterial hypertension and improve oxygenation in some patients with severe respiratory or heart failure. Despite this, iNO has not been found to improve survival. This study aimed to perform a local practice audit to assess the mortality predictors of critically ill patients who had received iNO as therapy for pulmonary hypertension and respiratory or heart failure. A retrospective audit in a single tertiary centre intensive care unit of patients receiving iNO was conducted between 2004 and 2009. The indications for iNO use, comorbidities, severity of illness, organ function, oxygenation, Sequential Organ Failure Assessment scores, patterns of iNO use, adverse events and outcomes were reviewed. In 215 patients receiving iNO, improvement in oxygenation after one hour from iNO commencement did not predict either intensive care unit (P = 0.36) or hospital (P = 0.72) mortality. The independent risk factors for intensive care unit mortality were worsening Sequential Organ Failure Assessment scores within 24 hours of commencing iNO (adjusted odds ratio 1.07, 95% confidence interval 1.05 to 1.18), the Charlson Comorbidity Score (adjusted odds ratio 1.49, 95% confidence interval 1.16 to 1.91) and the peak methaemoglobin concentration in arterial blood while receiving iNO (adjusted odds ratio 2.67, 95% confidence interval 1.42 to 4.96). Inhaled nitric oxide as salvage therapy for severe respiratory failure in critically ill patients is not routinely justified. Increased methaemoglobin concentration during iNO therapy, even when predominantly less than 3%, is associated with increased mortality.

Comparison of inhaled nitric oxide versus oxygen on hemodynamics in patients with mitral stenosis and severe pulmonary hypertension after mitral valve surgery

Pulmonary hypertension represents an important cause of morbidity and mortality in patients with mitral stenosis who undergo cardiac surgery, especially in the postoperative period. The aim of this study was to test the hypothesis that inhaled nitric oxide (iNO) would improve the hemodynamic effects and short-term clinical outcomes of patients with mitral stenosis and severe pulmonary hypertension who undergo cardiac surgery in a randomized, controlled study. Twenty-nine patients (4 men, 25 women; mean age 46 ± 2 years) were randomly allocated to receive iNO (n = 14) or oxygen (n = 15) for 48 hours immediately after surgery. Hemodynamic data, the use of vasoactive drugs, duration of stay, and short-term complications were assessed. No differences in baseline characteristics were observed between the groups. After 24 and 48 hours, patients receiving iNO had a significantly greater increase in cardiac index compared to patients receiving oxygen (p <0.0001). Pulmonary vascular resistance was also more significantly reduced in patients receiving iNO versus oxygen (-117 dyne/s/cm(5), 95% confidence interval -34 to -200, vs 40 dyne/s/cm(5), 95% confidence interval -34 to 100, p = 0.005) at 48 hours. Patients in the iNO group used fewer systemic vasoactive drugs (mean 2.1 ± 0.14 vs 2.6 ± 0.16, p = 0.046) and had a shorter intensive care unit stay (median 2 days, interquartile range 0.25, vs median 3 days, interquartile range 7, p = 0.02). In conclusion, iNO immediately after surgery in patients with mitral stenosis and severe pulmonary hypertension improves hemodynamics and may have short-term clinical benefits.

Medical and surgical treatment of acute right ventricular failure

Acute right ventricular (RV) failure is a frequent and serious clinical challenge in the intensive care unit. It is usually seen as a consequence of left ventricular failure, pulmonary embolism, pulmonary hypertension, sepsis, acute lung injury or after cardiothoracic surgery. The presence of acute RV failure not only carries substantial morbidity and mortality, but also complicates the use of commonly used treatment strategies in critically ill patients. In contrast to the left ventricle, the RV remains relatively understudied, and investigations of the treatment of isolated RV failure are rare and usually limited to nonrandomized observations. We searched PubMed for papers in the English language by using the search words right ventricle, right ventricular failure, pulmonary hypertension, sepsis, shock, acute lung injury, cardiothoracic surgery, mechanical ventilation, vasopressors, inotropes, and pulmonary vasodilators. These were used in various combinations. We read the abstracts of the relevant titles to confirm their relevance, and the full papers were then extracted. References from extracted papers were checked for any additional relevant papers. This review summarizes the general measures, ventilation strategies, vasoactive substances, and surgical as well as mechanical approaches that are currently used or actively investigated in the treatment of the acutely failing RV.

Inhaled epoprostenol for the treatment of pulmonary arterial hypertension in critically ill adults

Pulmonary arterial hypertension (PAH) is a progressive disease without a cure. The primary treatment goal for patients with this disease is improving pulmonary blood flow through vasodilation of the pulmonary arteries. Several drugs are available that ameliorate walk distance and hemodynamics, but their maximum tolerated doses are limited in critically ill patients with PAH because of systemic vasodilation resulting in hypotension. The ideal vasodilator would be cost-effective, safe, and selective to the pulmonary vasculature; no such agent currently exists. Inhaled nitric oxide selectively reduces pulmonary pressures without systemic hypotension. However, it is expensive, potentially toxic, and requires complex technology for monitoring and administration. Inhaled epoprostenol may be an alternative therapy to minimize systemic hypotension, which often accompanies rapid intravenous titration. To evaluate the safety and efficacy of inhaled epoprostenol in critically ill patients with PAH, we conducted a literature search by using the MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases (1966-August 2009) for relevant studies. Case reports and in vitro studies were excluded. Overall, 11 studies met the inclusion criteria. The PAH population included patients requiring cardiac surgery, lung or heart transplantation, or nonspecific intensive care. All trials showed that inhaled epoprostenol significantly decreased pulmonary pressures without lowering systemic blood pressure. The duration of therapy in most studies was 10-15 minutes, with one study evaluating its effects up to an average of 45.6 hours. Pulmonary pressures returned to baseline soon after drug discontinuation. Minimal adverse events were reported. Thus, inhaled epoprostenol in various subgroups of critically ill patients was effective in reducing pulmonary pressures. However, the significance of these effects on improving clinical outcomes remains unknown. Further studies are needed to determine the role of inhaled epoprostenol in critically ill patients with PAH.

Optimizing post-transplant outcomes in lung transplantation

Lung transplant recipients are at risk of numerous complications, which range from early events, such as primary graft dysfunction, to late events, including opportunistic infection or graft loss caused by chronic rejection. Although lung transplantation is often the only therapeutic option that can improve quality of life and prolong survival for many forms of end-stage lung disease, survival following lung transplantation is significantly worse than survival following transplantation of other solid organs. Carefully choosing potential recipients for listing, maximizing the likelihood that donor organs will function well following implantation, appropriate use of immunosuppressive agents to prevent allograft rejection, prophylactic or pre-emptive strategies to prevent allograft infection and appropriate surveillance to detect significant complications are key to maximizing the likelihood of prolonged graft and patient survival while avoiding significant complications following lung transplantation. Post-transplant outcomes will be optimized by a team approach to comprehensive management of the lung transplantation recipient combined with vigilant surveillance to detect complications in a timely fashion.

Managing drugs and devices in patients with permanent ventricular assist devices

Patients will be considered for destination mechanical circulatory support device (MCSD) implantation when all other organ-saving treatment options have failed and they are not eligible for heart transplantation. Current medical evidence suggests that only for those patients who are inotrope-dependent and therefore likely have a 1-year survival probability without MCSD implantation of less than 50%, MCSD intervention will add to survival and quality-of-life benefit. Suitable candidates for MCSD are those patients who have a high risk of dying from heart failure but acceptable noncardiac risk. Evaluation of patients for MCSD requires a systematic and critical review of all organ systems and of the psychosocial situation. Specifically, right ventricular function and risk of right ventricular failure should be evaluated before planning destination MCSD implantation. Treatment will focus on prompt recovery from MCSD implantation, maintaining optimal treatment for heart failure, and preventing/treating MCSD complications, including infection, bleeding, coagulopathy, right heart failure, and device dysfunction. MCSD programs should be organized as an advanced heart failure center directed by specialized heart failure cardiologists, surgeons expert at implant and management of MCSD, specialized nurses, social workers, psychologists, financial experts, and physical therapists. MCSD practice is based on a patient-centered theory, with an appropriate understanding of the respective roles of the physician and the patient during their iterative encounters in which the patient is an autonomous person making responsible personal health decisions while the health care team is providing continued expert and empathic counseling about various options, based on systematic outcomes research (eg, by participation in the Interagency Registry for Mechanically Assisted Circulatory Support - MCSD database ).

The management of acute pulmonary arterial hypertension

Acute pulmonary arterial hypertension (PAH), which may complicate the course of many complex disorders, is always underdiagnosed and its treatment frequently begins only after serious complications have developed. Acute PAH is distinctive because they differ in their clinical presentation, diagnostic findings, and response to treatment from chronic PAH. The acute PAH may take either the form of acute onset of chronic PAH or acute PAH or surgery-related PAH. Significant pathophysiologic differences existed between acute and chronic PAH. Therapy of acute PAH should generally be aimed at acutely relieving right ventricular (RV) pressure overload and preventing RV dysfunction. There are three classes of drugs targeting the correction of abnormalities in endothelial dysfunction, which have been approved recently for the treatment of PAH: (1) prostanoids; (2) endothelin receptor antagonists; and (3) phosphodiesterase-5 inhibitors. The efficacy and safety of these compounds have been confirmed in uncontrolled studies in patients with PAH. Intravenous epoprostenol is suggested to serve as the first-line treatment for the most severe patients. In the other situations, the first-line therapy may include bosentan, sildenafil, or a prostacyclin analogue. Recent advances in the management of PAH have markedly improved prognosis.

Acute right ventricular failure after pediatric cardiac transplant: predictors and long-term outcome in current era of transplantation medicine

OBJECTIVES

To identify pretransplant factors associated with postprocedural right ventricular failure and the relationship between right ventricular failure and long-term survival in children.

METHODS

Records were reviewed for children having heart transplantation from 2000 to 2006.

RESULTS

Right ventricular failure was identified by clinical and echocardiographic parameters in 33/129 (25%) recipients: dilated cardiomyopathy in 14/90 (15%), congenital heart disease in 11/27 (41%), and restrictive cardiomyopathy in 8/12 (66%). In 9 of 12 (75%), known elevated (reactive) pulmonary vascular resistance progressed to right ventricular failure. In a further 23/117 (20%) recipients, pulmonary vascular resistance within predefined acceptable range progressed to right ventricular failure. Multiple logistic regression analyses indicated elevated pulmonary vascular resistance (odds ratio 12.30; 95% confidence interval 2.73, 55.32; P = .001) and primary diagnosis, restrictive cardiomyopathy (odds ratio 9.21; 95% confidence interval 2.07, 41.12; P = .004), and congenital heart disease (odds ratio 4.07; 95% confidence interval 1.36, 12.19; P = .012) were strongly associated with right ventricular failure, but duration of heart failure, pretransplant mechanical support, donor status, and ischemic times were not. Treatment included inhaled nitric oxide in 28 (84%), mechanical support in 10 (31%), hemofiltration in 13 (40%), and retransplantation in 2. A Cox multiple regression model including: primary diagnosis, right ventricular failure, and elevated pulmonary vascular resistance indicated that only the latter was independently linked with eventual mortality (hazards ratio 5.45; 95% confidence interval 1.36, 21.96; P = .017).

CONCLUSIONS

Primary diagnosis and pretransplant elevated reactive pulmonary vascular resistance are both linked to the evolution of right ventricular failure. Pulmonary vascular resistance assessment in end-stage heart failure is challenging; therefore, avoidance of right ventricular failure may not always be possible. Aggressive early treatment may mitigate the effects of right ventricular failure: pretransplant elevated pulmonary vascular resistance was independently associated with long-term survival, but right ventricular failure was not.

Bench-to-bedside review: Inhaled nitric oxide therapy in adults

Nitric oxide (NO) is an endogenous mediator of vascular tone and host defence. Inhaled nitric oxide (iNO) results in preferential pulmonary vasodilatation and lowers pulmonary vascular resistance. The route of administration delivers NO selectively to ventilated lung units so that its effect augments that of hypoxic pulmonary vasoconstriction and improves oxygenation. This 'Bench-to-bedside' review focuses on the mechanisms of action of iNO and its clinical applications, with emphasis on acute lung injury and the acute respiratory distress syndrome. Developments in our understanding of the cellular and molecular actions of NO may help to explain the hitherto disappointing results of randomised controlled trials of iNO.

Inhalational therapies for the ICU

PURPOSE OF REVIEW

Although drug therapy is most commonly delivered via the intravenous route, novel inhaled agents have been introduced for use in the ICU. Additionally, drugs previously delivered intravenously are now being delivered via the respiratory tract in an effort to reduce systemic toxicity and maximize effectiveness.

RECENT FINDINGS

Aerosolized antibiotics have seen increased use in an effort to reduce systemic effects, reduce ventilator-associated pneumonia, and direct high drug concentrations at the site of infection. Drug-resistant pneumonia has also been effectively treated with aerosolized antibiotics. Secretion management includes a host of devices, therapies, and drugs, but the evidence for these is scant. Cardiac drugs via the endotracheal route should be used only when intravenous access is delayed. Inhaled nitric oxide has a defined role in care of infants, although new indications have limited and conflicting data. The use of helium-oxygen mixtures provides symptom relief in a wide variety of scenarios associated with turbulent flow in large airways.

SUMMARY

Inhaled nitric oxide has an established role in neonatal intensive care and a limited role in adult intensive care. Heliox provides symptom relief, but at present cannot be considered routine as a consequence of the multiple technological challenges. Inhaled antimicrobials appear to provide a therapeutic advantage in select individuals with pneumonia. Secretion management is best achieved by adequate humidification and as needed suctioning. The role of inhaled carbon monoxide in critical care holds significant promise, but is currently in early clinical trials.

Arterial pulmonary hypertension in noncardiac intensive care unit

Pulmonary artery pressure elevation complicates the course of many complex disorders treated in a noncardiac intensive care unit. Acute pulmonary hypertension, however, remains underdiagnosed and its treatment frequently begins only after serious complications have developed. Significant pathophysiologic differences between acute and chronic pulmonary hypertension make current classification and treatment recommendations for chronic pulmonary hypertension barely applicable to acute pulmonary hypertension. In order to clarify the terminology of acute pulmonary hypertension and distinguish it from chronic pulmonary hypertension, we provide a classification of acute pulmonary hypertension according to underlying pathophysiologic mechanisms, clinical features, natural history, and response to treatment. Based on available data, therapy of acute arterial pulmonary hypertension should generally be aimed at acutely relieving right ventricular (RV) pressure overload and preventing RV dysfunction. Cases of severe acute pulmonary hypertension complicated by RV failure and systemic arterial hypotension are real clinical challenges requiring tight hemodynamic monitoring and aggressive treatment including combinations of pulmonary vasodilators, inotropic agents and systemic arterial vasoconstrictors. The choice of vasopressor and inotropes in patients with acute pulmonary hypertension should take into consideration their effects on vascular resistance and cardiac output when used alone or in combinations with other agents, and must be individualized based on patient response.

Therapeutic antioxidant medical gas

Medical gases are pharmaceutical gaseous molecules which offer solutions to medical needs and include traditional gases, such as oxygen and nitrous oxide, as well as gases with recently discovered roles as biological messenger molecules, such as carbon monoxide, nitric oxide and hydrogen sulphide. Medical gas therapy is a relatively unexplored field of medicine; however, a recent increasing in the number of publications on medical gas therapies clearly indicate that there are significant opportunities for use of gases as therapeutic tools for a variety of disease conditions. In this article, we review the recent advances in research on medical gases with antioxidant properties and discuss their clinical applications and therapeutic properties.

[Pulmonary hypertension and right ventricular failure in critical care medicine]

The management of pulmonary hypertension and right ventricular failure in hemodynamically unstable patients is one of the most challenging situations in critical care medicine. Inadequate therapy, e.g. aggressive fluid resuscitation or invasive ventilation, may even harm patients with pulmonary hypertension. Identifying the underlying etiology therefore remains the primary focus for initiating successful management of patients with decompensated pulmonary hypertension and right ventricular failure. Pulmonary embolism requires immediate restoration of pulmonary vascular patency. The body of evidence from studies is scarce and favors dobutamine, NO inhalation, and intravenous prostacyclin. However, the use of other vasoactive substances, inotropes, and supportive measures has been successful in individual patients; it should be guided by the expected effects on the pulmonary vasculature or right ventricle, and should be adapted to the patient's concomitant diseases.

Management strategies for patients with pulmonary hypertension in the intensive care unit

OBJECTIVE

Pulmonary hypertension may be encountered in the intensive care unit in patients with critical illnesses such as acute respiratory distress syndrome, left ventricular dysfunction, and pulmonary embolism, as well as after cardiothoracic surgery. Pulmonary hypertension also may be encountered in patients with preexisting pulmonary vascular, lung, liver, or cardiac diseases. The intensive care unit management of patients can prove extremely challenging, particularly when they become hemodynamically unstable. The objective of this review is to discuss the pathogenesis and physiology of pulmonary hypertension and the utility of various diagnostic tools, and to provide recommendations regarding the use of vasopressors and pulmonary vasodilators in intensive care.

DATA SOURCES AND EXTRACTION

We undertook a comprehensive review of the literature regarding the management of pulmonary hypertension in the setting of critical illness. We performed a MEDLINE search of articles published from January 1970 to March 2007. Medical subject headings and keywords searched and cross-referenced with each other were: pulmonary hypertension, vasopressor agents, therapeutics, critical illness, intensive care, right ventricular failure, mitral stenosis, prostacyclin, nitric oxide, sildenafil, dopamine, dobutamine, phenylephrine, isoproterenol, and vasopressin. Both human and animal studies related to pulmonary hypertension were reviewed.

CONCLUSIONS

Pulmonary hypertension presents a particular challenge in critically ill patients, because typical therapies such as volume resuscitation and mechanical ventilation may worsen hemodynamics in patients with pulmonary hypertension and right ventricular failure. Patients with decompensated pulmonary hypertension, including those with pulmonary hypertension associated with cardiothoracic surgery, require therapy for right ventricular failure. Very few human studies have addressed the use of vasopressors and pulmonary vasodilators in these patients, but the use of dobutamine, milrinone, inhaled nitric oxide, and intravenous prostacyclin have the greatest support in the literature. Treatment of pulmonary hypertension resulting from critical illness or chronic lung diseases should address the primary cause of hemodynamic deterioration, and pulmonary vasodilators usually are not necessary.