Inhaled nitric oxide therapy in adults: European expert recommendations

Impact of Inhaled Nitric Oxide (iNO) on the Outcome of COVID-19 Associated ARDS

Background: Inhaled nitric oxide (iNO) can improve oxygenation in acute respiratory syndrome (ARDS), has anti-inflammatory and antithrombotic effects, and can inhibit coronavirus- replication. The study aim was to investigate the impact of iNO in COVID-19 associated ARDS (CARDS) on oxygenation, the length of mechanical ventilation (MV), the level of inflammatory markers and the rate of thrombotic events during ICU stay. Methods: This was a retrospective, observational, monocentric study analyzing the effect of INO (15 parts per million) vs. non-iNO in adult ventilated CARDS patients on oxygenation, the level of inflammatory markers, and the rate of thrombotic events during ICU stay. Within the iNO group, the impact on gas exchange was assessed by comparing arterial blood gas results obtained at different time points. Results: Overall, 19/56 patients were treated with iNO, with no difference regarding sex, age, body mass index, and SOFA-/APACHE II- score between the iNO and non-iNO groups. iNO improved oxygenation in iNO-responders (7/19) and had no impact on inflammatory markers or the rate of thrombotic events but was associated with an increased MV length. Conclusions: iNO was able to improve oxygenation in CARDS in iNO-responders but did not show an impact on inflammatory markers or the rate of thrombotic events, while it was associated with an increased MV length.

Advances in the potential of nebulized inhalation for the treatment of pulmonary arterial hypertension

Pulmonary hypertension is a pathophysiologic manifestation of a heterogeneous group of diseases, with the main pathophysiologic mechanisms being persistent pulmonary vasoconstriction and irreversible vascular remodeling. The impact significantly affects the prognosis of patients with pulmonary hypertension. If it is not treated and intervened in time, it may lead to right ventricular failure and further endanger the patient's life. Within the past decade or so, nebulized inhalation therapy is considered to have advantages in the treatment of pulmonary hypertension as a safe, limited, and rapid therapy, for example, inhaled vasodilators (prostate analogs, nitroglycerin, carbon monoxide analogs sildenafil, and nitroprusside), inhaled anti-inflammatory and antiproliferative agents (simvastatin, and selatinib), and inhaled peroxides (levocetirizine) have been recognized as emerging therapeutic approaches in the treatment of pulmonary hypertension as emerging therapeutic approaches. Therefore, this article provides a brief review of recent advances in the potential of nebulized inhaled vasodilators, anti-inflammatory and antiproliferative agents, and anti-peroxides for the treatment of pulmonary hypertension, with the aim of providing different therapeutic options for the treatment of pulmonary hypertension, enhancing the quality of survival, alleviating symptoms, and improving the prognosis of patients with this condition.

Modes of administration of nitric oxide devices and ventilators flow-by impact the delivery of pre-determined concentrations

BACKGROUND

Nitric oxide (NO) is a strong vasodilator, selectively directed on pulmonary circulation through inhaled administration. In adult intensive care units (ICU), it is mainly used for refractory hypoxemia in mechanically ventilated patients. Several medical delivery devices have been developed to deliver inhaled nitric oxide (iNO). The main purpose of those devices is to guarantee an accurate inspiratory NO concentration, whatever the ventilator used, with NO2 concentrations lower than 0.3 ppm. We hypothesized that the performances of the different available iNO delivery systems could depend on their working principle and could be influenced by the ventilator settings. The objective of this study was to assess the accuracy of seven different iNO-devices combined with different ICU ventilators' flow-by to reach inspiratory NO concentration targets and to evaluate their potential risk of toxicity.

METHODS

We tested seven iNO-devices on a test-lung connected to distinct ICU ventilators offering four different levels of flow-by. We measured the flow in the inspiratory limb of the patient circuit and the airway pressure. The nitric oxide/nitrogen (NO/N2) flow was measured on the administration line of the iNO-devices. NO and NO2 concentrations were measured in the test-lung using an electrochemical analyzer.

RESULTS

We identified three iNO-device generations based on the way they deliver NO flow: "Continuous", "Sequential to inspiratory phase" (I-Sequential) and "Proportional to inspiratory and expiratory ventilator flow" (Proportional). Median accuracy of iNO concentration measured in the test lung was 2% (interquartile range, IQR -19; 36), -23% (IQR -29; -17) and 0% (IQR -2; 0) with Continuous, I-Sequential and Proportional devices, respectively. Increased ventilator flow-by resulted in decreased iNO concentration in the test-lung with Continuous and I-Sequential devices, but not with Proportional ones. NO2 formation measured to assess potential risks of toxicity never exceeded the predefined safety target of 0.5 ppm. However, NO2 concentrations higher than or equal to 0.3 ppm, a concentration that can cause bronchoconstriction, were observed in 19% of the different configurations.

CONCLUSION

We identified three different generations of iNO-devices, based on their gas administration modalities, that were associated with highly variable iNO concentrations' accuracy. Ventilator's flow by significantly impacted iNO concentration. Only the Proportional devices permitted to accurately deliver iNO whatever the conditions and the ventilators tested.

Real-world safety and effectiveness of inhaled nitric oxide therapy for pulmonary hypertension during the perioperative period of cardiac surgery: a post-marketing study of 2817 patients in Japan

OBJECTIVE

To evaluate the real-world safety and effectiveness of inhaled nitric oxide (INOflo® for Inhalation 800 ppm) for perioperative pulmonary hypertension associated with cardiac surgery in Japan.

METHODS

This was a prospective, non-interventional, all-case, post-marketing study of pediatric and adult patients who received perioperative INOflo with cardiac surgery from November 2015-December 2020. Safety and effectiveness were monitored from INOflo initiation to 48 h after treatment completion or withdrawal. Safety outcomes included adverse drug reactions, blood methemoglobin concentrations, and inspired nitrogen dioxide concentrations over time. Effectiveness outcomes included changes in central venous pressure among pediatrics, mean pulmonary arterial pressure among adults, and the partial pressure of arterial oxygen/fraction of inspired oxygen ratio (PaO2/FiO2) in both populations.

RESULTS

The safety analysis population included 2,817 Japanese patients registered from 253 clinical sites (pediatrics, n = 1375; adults, n = 1442). INOflo was generally well tolerated; 15 and 20 adverse drug reactions were reported in 14 pediatrics (1.0%) and 18 adults (1.2%), respectively. No clinically significant elevations in blood methemoglobin and inspired nitrogen dioxide concentrations were observed. INOflo treatment was associated with significant reductions in both central venous pressure among pediatrics and mean pulmonary arterial pressure among adults, and significant improvements in PaO2/FiO2 among pediatrics and adults with PaO2/FiO2 ≤ 200 at baseline.

CONCLUSIONS

Perioperative INOflo treatment was a safe and effective strategy to improve hemodynamics and oxygenation in patients with pulmonary hypertension during cardiac surgery. These data support the use of INOflo for this indication in Japanese clinical practice.

Inhaled NO at a crossroads in cardiac surgery: current need to improve mechanistic understanding, clinical trial design and scientific evidence

Inhaled nitric oxide (NO) has been used in pediatric and adult perioperative cardiac intensive care for over three decades. NO is a cellular signaling molecule that induces smooth muscle relaxation in the mammalian vasculature. Inhaled NO has the unique ability to exert its vasodilatory effects in the pulmonary vasculature without any hypotensive side-effects in the systemic circulation. In patients undergoing cardiac surgery, NO has been reported in numerous studies to exert beneficial effects on acutely lowering pulmonary artery pressure and reversing right ventricular dysfunction and/or failure. Yet, various investigations failed to demonstrate significant differences in long-term clinical outcomes. The authors, serving as an advisory board of international experts in the field of inhaled NO within pediatric and adult cardiac surgery, will discuss how the existing scientific evidence can be further improved. We will summarize the basic mechanisms underlying the clinical applications of inhaled NO and how this translates into the mandate for inhaled NO in cardiac surgery. We will move on to the popular use of inhaled NO and will talk about the evidence base of the use of this selective pulmonary vasodilator. This review will elucidate what kind of clinical and biological barriers and gaps in knowledge need to be solved and how this has impacted in the development of clinical trials. The authors will elaborate on how the optimization of inhaled NO therapy, the development of biomarkers to identify the target population and the definition of response can improve the design of future large clinical trials. We will explain why it is mandatory to gain an international consensus for the state of the art of NO therapy far beyond this expert advisory board by including the different major players in the field, such as the different medical societies and the pharma industry to improve our understanding of the real-life effects of inhaled NO in large scale observational studies. The design for future innovative randomized controlled trials on inhaled NO therapy in cardiac surgery, adequately powered and based on enhanced biological phenotyping, will be crucial to eventually provide scientific evidence of its clinical efficacy beyond its beneficial hemodynamic properties.

A 1-month-old infant with pulmonary hypertensive crisis after cardiac surgery was successfully rescued with connection of left atrial and right ventricular pressure measurement tubes: a case report

Background

Pulmonary hypertensive crisis is a complication with extremely high mortality after surgery of congenital heart disease. However, there are still no treatment guidelines or expert consensus on the standard treatment of pulmonary hypertensive crisis, and the effect of conventional treatment is still unsatisfactory. We present a case of a patient who developed pulmonary hypertensive crisis after cardiac surgery, and was successfully rescued with a pioneering method, which has never been reported so far.

Case summary

An infant with congenital heart disease had undergone cardiac surgery successfully. Due to obvious myocardial oedema, sternal closure was delayed. The left atrial and right ventricular pressure monitoring tubes, both of which were connected through a triplet, were inserted into right pulmonary vein and pulmonary artery, respectively, and the triplet was in closed condition. On the night of the surgery, pulmonary hypertensive crisis occurred. Emergency bedside thoracotomy was given, and the triplet was turned on urgently to make the left atrial and right ventricular pressure monitoring tubes connected. Meantime, conventional treatment was performed. Eventually, the pulmonary hypertensive crisis was quickly relieved, and the infant was discharged 9 days later.

Discussion

The left atrial and right ventricular pressure monitoring tubes are placed intraoperatively in patients who both need delayed sternal closure and have high risk factors for pulmonary hypertensive crisis, by which could not only monitor the pressure of left atrium and right ventricle in real time but also effectively relieve the right ventricular pressure instantaneously when pulmonary hypertensive crisis occurs, as well as remedy ischaemia of systemic and coronary circulation.

Delivery exogenous nitric oxide via cardiopulmonary bypass in pediatric cardiac surgery reduces the duration of postoperative mechanical ventilation-A meta-analysis of randomized controlled trials

Objectives

Cardiopulmonary bypass (CPB) is a major part of cardiac surgery that provokes systemic inflammatory reactions, myocardial ischemia, and ischemia and reperfusion damage. The aim of this study is to summarize the available evidence and evaluate whether exogenous nitric oxide administered via CPB circuits can improve recovery after cardiac surgery in children.

Method

A comprehensive search of the PubMed Medline, Ovid, Cochrane Library and Embase databases was conducted in September 2022. Only randomized controlled trials that compared nitro oxide with placebo or standard care were included.

Results

This pooled analysis included 5 RCTs containing 1642 patients. There were significant differences in the duration of postoperative mechanical ventilation between the nitric oxide group and the control group (mean difference -5.645 h; 95% CL = -9.978, -1.313; P = 0.01). Meta-analysis of the length of ICU stay and hospital stay showed no significant differences.

Conclusion

Delivering nitric oxide via CPB in pediatric cardiac surgery has an effect on reducing the duration of mechanical ventilation. Considering the small effect size, we should be cautious and think comprehensively in clinical practice.

Pharmacologic therapies of ARDS: From natural herb to nanomedicine

Acute respiratory distress syndrome (ARDS) is a common critical illness in respiratory care units with a huge public health burden. Despite tremendous advances in the prevention and treatment of ARDS, it remains the main cause of intensive care unit (ICU) management, and the mortality rate of ARDS remains unacceptably high. The poor performance of ARDS is closely related to its heterogeneous clinical syndrome caused by complicated pathophysiology. Based on the different pathophysiology phases, drugs, protective mechanical ventilation, conservative fluid therapy, and other treatment have been developed to serve as the ARDS therapeutic methods. In recent years, there has been a rapid development in nanomedicine, in which nanoparticles as drug delivery vehicles have been extensively studied in the treatment of ARDS. This study provides an overview of pharmacologic therapies for ARDS, including conventional drugs, natural medicine therapy, and nanomedicine. Particularly, we discuss the unique mechanism and strength of nanomedicine which may provide great promises in treating ARDS in the future.

Inhaled Nitric Oxide for Clinical Management of COVID-19: A Systematic Review and Meta-Analysis

BACKGROUND

Severe COVID-19 is associated with hypoxemia and acute respiratory distress syndrome (ARDS), which may predispose multiorgan failure and death. Inhaled nitric oxide (iNO) is a clinical vasodilator used in the management of acute respiratory distress syndrome (ARDS). This study evaluated the response rate to iNO in patients with COVID-19-ARDS.

METHOD

We searched Medline and Embase databases in May 2022, and data on the use of iNO in the treatment of ARDS in COVID-19 patients were synthesized from studies that satisfied predefined inclusion criteria. A systematic synthesis of data was performed followed by meta-analysis. We performed the funnel plot and leave-one-out sensitivity test on the included studies to assess publication bias and possible exaggerated effect size. We compared the effect size of the studies from the Unites States with those from other countries and performed meta-regression to assess the effect of age, year of publication, and concomitant vasodilator use on the effect size.

RESULTS

A total of 17 studies (including 712 COVID-19 patients) were included in this systematic review of which 8 studies (involving 265 COVID-19 patients) were subjected to meta-analysis. The overall response rate was 66% (95% CI, 47-84%) with significantly high between-studies heterogeneity (I2 = 94%, p < 0.001). The funnel plot showed publication bias, although the sensitivity test using leave-one-out analysis showed that removing any of the study does not remove the significance of the result. The response rate was higher in the Unites States, and meta-regression showed that age, year of publication, and use of concomitant vasodilators did not influence the response rate to iNO.

CONCLUSION

iNO therapy is valuable in the treatment of hypoxemia in COVID-19 patients and may improve systemic oxygenation in patients with COVID-19-ARDS. Future studies should investigate the mechanism of the activity of iNO in COVID-19 patients to provide insight into the unexplored potential of iNO in general ARDS.

In vitro validation and characterization of pulsed inhaled nitric oxide administration during early inspiration

PURPOSE

Admixture of nitric oxide (NO) to the gas inspired with mechanical ventilation can be achieved through continuous, timed, or pulsed injection of NO into the inspiratory limb. The dose and timing of NO injection govern the inspired and intrapulmonary effect site concentrations achieved with different administration modes. Here we test the effectiveness and target reliability of a new mode injecting pulsed NO boluses exclusively during early inspiration.

METHODS

An in vitro lung model was operated under various ventilator settings. Admixture of NO through injection into the inspiratory limb was timed either (i) selectively during early inspiration ("pulsed delivery"), or as customary, (ii) during inspiratory time or (iii) the entire respiratory cycle. Set NO target concentrations of 5-40 parts per million (ppm) were tested for agreement with the yield NO concentrations measured at various sites in the inspiratory limb, to assess the effectiveness of these NO administration modes.

RESULTS

Pulsed delivery produced inspiratory NO concentrations comparable with those of customary modes of NO administration. At low (450 ml) and ultra-low (230 ml) tidal volumes, pulsed delivery yielded better agreement of the set target (up to 40 ppm) and inspiratory NO concentrations as compared to customary modes. Pulsed delivery with NO injection close to the artificial lung yielded higher intrapulmonary NO concentrations than with NO injection close to the ventilator. The maximum inspiratory NO concentration observed in the trachea (68 ± 30 ppm) occurred with pulsed delivery at a set target of 40 ppm.

CONCLUSION

Pulsed early inspiratory phase NO injection is as effective as continuous or non-selective admixture of NO to inspired gas and may confer improved target reliability, especially at low, lung protective tidal volumes.

Inhaled Nitric Oxide Treatment for Aneurysmal SAH Patients With Delayed Cerebral Ischemia

Background

We demonstrated experimentally that inhaled nitric oxide (iNO) dilates hypoperfused arterioles, increases tissue perfusion, and improves neurological outcome following subarachnoid hemorrhage (SAH) in mice. We performed a prospective pilot study to evaluate iNO in patients with delayed cerebral ischemia after SAH.

Methods

SAH patients with delayed cerebral ischemia and hypoperfusion despite conservative treatment were included. iNO was administered at a maximum dose of 40 ppm. The response to iNO was considered positive if: cerebral artery diameter increased by 10% in digital subtraction angiography (DSA), or tissue oxygen partial pressure (PtiO₂) increased by > 5 mmHg, or transcranial doppler (TCD) values decreased more than 30 cm/sec, or mean transit time (MTT) decreased below 6.5 secs in CT perfusion (CTP). Patient outcome was assessed at 6 months with the modified Rankin Scale (mRS).

Results

Seven patients were enrolled between February 2013 and September 2016. Median duration of iNO administration was 23 h. The primary endpoint was reached in all patients (five out of 17 DSA examinations, 19 out of 29 PtiO₂ time points, nine out of 26 TCD examinations, three out of five CTP examinations). No adverse events necessitating the cessation of iNO were observed. At 6 months, three patients presented with a mRS score of 0, one patient each with an mRS score of 2 and 3, and two patients had died.

Conclusion

Administration of iNO in SAH patients is safe. These results call for a larger prospective evaluation.

Delivery of Nitric Oxide in the Cardiovascular System: Implications for Clinical Diagnosis and Therapy

Nitric oxide (NO) is a key molecule in cardiovascular homeostasis and its abnormal delivery is highly associated with the occurrence and development of cardiovascular disease (CVD). The assessment and manipulation of NO delivery is crucial to the diagnosis and therapy of CVD, such as endothelial dysfunction, atherosclerotic progression, pulmonary hypertension, and cardiovascular manifestations of coronavirus (COVID-19). However, due to the low concentration and fast reaction characteristics of NO in the cardiovascular system, clinical applications centered on NO delivery are challenging. In this tutorial review, we first summarized the methods to estimate the in vivo NO delivery process, based on computational modeling and flow-mediated dilation, to assess endothelial function and vulnerability of atherosclerotic plaque. Then, emerging bioimaging technologies that have the potential to experimentally measure arterial NO concentration were discussed, including Raman spectroscopy and electrochemical sensors. In addition to diagnostic methods, therapies aimed at controlling NO delivery to regulate CVD were reviewed, including the NO release platform to treat endothelial dysfunction and atherosclerosis and inhaled NO therapy to treat pulmonary hypertension and COVID-19. Two potential methods to improve the effectiveness of existing NO therapy were also discussed, including the combination of NO release platform and computational modeling, and stem cell therapy, which currently remains at the laboratory stage but has clinical potential for the treatment of CVD.

Nitroglycerin inhalation for acute treatment of pulmonary arterial hypertension in children with congenital heart disease

OBJECTIVES

Acute pulmonary hypertension and pulmonary hypertensive crisis may result in adverse clinical outcomes if unsuccessfully treated. Inhaled nitric oxide has long been considered as the standard pharmacotherapy for acute pulmonary hypertension, but lack of feasibility in some settings and evidences challenging its benefits lead to the use of alternative treatment, amongst which is nitroglycerin inhalation. The purpose of this review article is to discuss available data on the use of nitroglycerin inhalation for acute treatment of pulmonary hypertension in children with CHD and its potential benefit in post-operative setting.

DATA SOURCES

Literatures included in this review were acquired by searching in PubMed online database. Keywords used were "Pulmonary Hypertension", "Congenital heart defects", "Pediatrics", "Inhaled nitroglycerin", and its synonyms.

STUDY SELECTION

Title and abstract were screened to select relevant literatures including the three paediatric clinical trials on nitroglycerin inhalation. Critical appraisal of the clinical trials was then done using the University of Oxford Centre of Evidence-Based Medicine Critical Appraisal Tools.

CONCLUSIONS

Paediatric studies showed the benefit of nitroglycerin inhalation in uncorrected cases of CHD during catheterisation procedures. Until recently, there have been no studies conducted in paediatric post-operative CHD cases. Further study is required to provide evidence for inhaled nitroglycerin use in this setting including the appropriate dosing and potential side effects with repeated administration.

Post-operative Right Ventricular Failure After Cardiac Surgery: A Cohort Study

Introduction: Right ventricular failure (RVF) after cardiac surgery is an important risk factor for morbidity and mortality. Its diagnosis is challenging, and thus, its incidence and predictors are not well-established. We investigated the incidence, complications, and variables associated with clinically relevant post-operative RVF.

Methods: We included all patients who underwent cardiac surgery with cardiopulmonary bypass between 2016 and 2019 in a cardiac surgery center with standardized diagnostic and therapeutic management of RVF. RVF was considered only if clinically relevant: associated with hemodynamic instability requiring catecholamine support and inhaled nitric oxide relayed by sildenafil.

Results: Overall, 3,826 patients were included, of whom, 110 (2.9%) developed post-operative RVF. Mortality was not different among patients who developed post-operative RVF, compared with the rest of the cohort (1.8 vs. 0.7%, p = 0.17). Using a composite outcome that combined death, reintubation, stroke, and prolonged intensive care unit stay (more than 14 days) yielded an incidence of 6.6%, and RVF was associated with this composite outcome with an odds ratio of 3.6 (2.2–5.8), p < 0.001. In a multivariable model, pre-operative variables independently associated with post-operative RVF were pre-operative atrial fibrillation (AF) {adjusted odds ratio (adjOR) 3.22 [95% confidence interval (95%CI) = 1.94–5.36], p < 0.001}, left ventricle ejection fraction below 50% [adjOR = 2.55 (95%CI = 1.52–4.33), p < 0.001], systolic pulmonary artery pressure above 55 mmHg [adjOR = 8.64 (95%CI = 5.27–14.1); p < 0.001], mitral valve surgery [adjOR = 2.17 CI (95%CI = 1.28–3.66), p = 0.004], and tricuspid valve surgery [adjOR = 10.33 (95%CI = 6.14–17.4), p < 0.001]. In patients who developed post-operative RVF requiring treatment, 32 (29.1%) showed RV dysfunction before surgery.

Conclusion: In this cohort study, 2.9% of patients developed clinically significant post-operative RVF. Moreover, RVF was associated with severe adverse outcomes, including death, strokes, reintubation, and prolonged intensive care unit stay.

Early effects of ventilatory rescue therapies on systemic and cerebral oxygenation in mechanically ventilated COVID-19 patients with acute respiratory distress syndrome: a prospective observational study

BACKGROUND

In COVID-19 patients with acute respiratory distress syndrome (ARDS), the effectiveness of ventilatory rescue strategies remains uncertain, with controversial efficacy on systemic oxygenation and no data available regarding cerebral oxygenation and hemodynamics.

METHODS

This is a prospective observational study conducted at San Martino Policlinico Hospital, Genoa, Italy. We included adult COVID-19 patients who underwent at least one of the following rescue therapies: recruitment maneuvers (RMs), prone positioning (PP), inhaled nitric oxide (iNO), and extracorporeal carbon dioxide (CO2) removal (ECCO2R). Arterial blood gas values (oxygen saturation [SpO2], partial pressure of oxygen [PaO2] and of carbon dioxide [PaCO2]) and cerebral oxygenation (rSO2) were analyzed before (T0) and after (T1) the use of any of the aforementioned rescue therapies. The primary aim was to assess the early effects of different ventilatory rescue therapies on systemic and cerebral oxygenation. The secondary aim was to evaluate the correlation between systemic and cerebral oxygenation in COVID-19 patients.

RESULTS

Forty-five rescue therapies were performed in 22 patients. The median [interquartile range] age of the population was 62 [57-69] years, and 18/22 [82%] were male. After RMs, no significant changes were observed in systemic PaO2 and PaCO2 values, but cerebral oxygenation decreased significantly (52 [51-54]% vs. 49 [47-50]%, p < 0.001). After PP, a significant increase was observed in PaO2 (from 62 [56-71] to 82 [76-87] mmHg, p = 0.005) and rSO2 (from 53 [52-54]% to 60 [59-64]%, p = 0.005). The use of iNO increased PaO2 (from 65 [67-73] to 72 [67-73] mmHg, p = 0.015) and rSO2 (from 53 [51-56]% to 57 [55-59]%, p = 0.007). The use of ECCO2R decreased PaO2 (from 75 [75-79] to 64 [60-70] mmHg, p = 0.009), with reduction of rSO2 values (59 [56-65]% vs. 56 [53-62]%, p = 0.002). In the whole population, a significant relationship was found between SpO2 and rSO2 (R = 0.62, p < 0.001) and between PaO2 and rSO2 (R0 0.54, p < 0.001).

CONCLUSIONS

Rescue therapies exert specific pathophysiological mechanisms, resulting in different effects on systemic and cerebral oxygenation in critically ill COVID-19 patients with ARDS. Cerebral and systemic oxygenation are correlated. The choice of rescue strategy to be adopted should take into account both lung and brain needs. Registration The study protocol was approved by the ethics review board (Comitato Etico Regione Liguria, protocol n. CER Liguria: 23/2020).

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.

Inhaled Pulmonary Vasodilators and Thoracic Organ Transplantation: Does Evidence Support Its Use and Cost Benefit?

In heart transplantation, pulmonary hypertension and increased pulmonary vascular resistance followed by donor right ventricular dysfunction remain a major cause of perioperative morbidity and mortality. In lung transplantation, primary graft dysfunction remains a major obstacle because it can cause bronchiolitis obliterans and mortality. Pulmonary vasodilators have been used as an adjunct therapy for heart or lung transplantation, mainly to treat pulmonary hypertension, right ventricular failure, and associated refractory hypoxemia. Among pulmonary vasodilators, inhaled nitric oxide is unique in that it is selective in pulmonary circulation and causes fewer systemic complications such as hypotension, flushing, or coagulopathy. Nitric oxide is expected to prevent or attenuate primary graft dysfunction by decreasing ischemia-reperfusion injury in lung transplantation. However, when considering the long-term benefit of these medications, little evidence supports their use in heart or lung transplantation. Current guidelines endorse inhaled vasodilators for managing immediate postoperative right ventricular failure in lung or heart transplantation, but no guidance is offered regarding agent selection, dosing, or administration. This review presents the current evidence of inhaled nitric oxide in lung or heart transplantation as well as comparisons with other pulmonary vasodilators including cost differences in consideration of economic pressures to contain rising pharmacy costs.

A Stewardship Program to Optimize the Use of Inhaled Nitric Oxide in Pediatric Critical Care

PURPOSE

Inhaled nitric oxide (iNO) is a pulmonary vasodilator that is approved for use in term and near-term neonates with hypoxic respiratory failure associated with evidence of pulmonary hypertension. However, it is commonly used in infants and children to treat a variety of other cardiopulmonary diseases associated with pulmonary hypertension and hypoxic respiratory failure. In critically ill children, iNO therapy may be continued for a prolonged period, and this increases the risk for adverse consequences including toxicity and unnecessary costs. We implemented an iNO Stewardship Program with the aim of improving adherence to guidelines and reducing unnecessary iNO utilization.

METHODS

Between April 1, 2011, and March 31, 2015, a before and after cohort study was conducted at The Hospital for Sick Children. Prospective iNO usage and outcome variables in the poststewardship period were examined.

RESULTS

Patient characteristics and outcomes were similar before and after stewardship implementation. The number of iNO therapy courses were also similar in the before and after period. Inhaled nitric oxide utilization in the pediatric intensive care unit and the cardiac critical care unit decreased from 15 765 hours in the prestewardship period (April 2011 to March 2013) to 10 342 hours in the poststewardship period (April 2013 to March 2015), with significant improvement in adherence to the iNO guideline and a small decrease in expenditure (3%).

CONCLUSION

Implementation of the iNO Stewardship was successful at reducing overall iNO utilization. This quality improvement initiative helped us optimize practice and subsequently expand the methodology to inform the clinical indication for iNO.

New Modalities for the Administration of Inhaled Nitric Oxide in Intensive Care Units After Cardiac Surgery or for Neonatal Indications: A Prospective Observational Study

BACKGROUND

Nitric oxide (NO) has a well-known efficacy in pulmonary hypertension (PH), with wide use for 20 years in many countries. The objective of this study was to describe the current use of NO in real life and the gap with the guidelines.

METHODS

This is a multicenter, prospective, observational study on inhaled NO administered through an integrated delivery and monitoring device and indicated for PH according to the market authorizations. The characteristics of NO therapy and ventilation modes were observed. Concomitant pulmonary vasodilator treatments, safety data, and outcome were also collected. Quantitative data are expressed as median (25th, 75th percentile).

RESULTS

Over 1 year, 236 patients were included from 14 equipped and trained centers: 117 adults and 81 children with PH associated with cardiac surgery and 38 neonates with persistent PH of the newborn. Inhaled NO was initiated before intensive care unit (ICU) admission in 57%, 12.7%, and 38.9% with an initial dose of 10 (10, 15) ppm, 20 (18, 20) ppm, and 17 (11, 20) ppm, and a median duration of administration of 3.9 (1.9, 6.1) days, 3.8 (1.8, 6.8) days, and 3.1 (1.0, 5.7) days, respectively, for the adult population, pediatric cardiac group, and newborns. The treatment was performed using administration synchronized to the mechanical ventilation. The dose was gradually decreased before withdrawal in 86% of the cases according to the usual procedure of each center. Adverse events included rebound effect for 3.4% (95% confidence interval [CI], 0.9%-8.5%) of adults, 1.2% (95% CI, 0.0%-6.7%) of children, and 2.6% (95% CI, 0.1%-13.8%) of neonates and methemoglobinemia exceeded 2.5% for 5 of 62 monitored patients. Other pulmonary vasodilators were associated with NO in 23% of adults, 95% of children, and 23.7% of neonates. ICU stay was respectively 10 (6, 22) days, 7.5 (5.5, 15) days, and 9 (8, 15) days and ICU mortality was 22.2%, 6.2%, and 7.9% for adults, children, and neonates, respectively.

CONCLUSIONS

This study confirms the safety of NO therapy in the 3 populations with a low rate of rebound effect. Gradual withdrawal of NO combined with pulmonary vasodilators are current practices in this population. The use of last-generation NO devices allowed good compliance with recommendations.

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.

Initial clinical impact of inhaled nitric oxide therapy for refractory hypoxemia following type A acute aortic dissection surgery

BACKGROUND

To evaluate the effect of inhaled nitric oxide (iNO) therapy on oxygenation and clinical outcomes in patients with refractory hypoxemia after surgical reconstruction for acute type A aortic dissection (TAAD).

METHODS

A before-and-after interventional study was conducted in patients with refractory hypoxemia after surgical reconstruction for TAAD. Postoperative refractory hypoxemia was defined as a persistent PaO₂/FiO₂ ratio ≤100 mmHg despite conventional therapy. From January to November 2016, conventional treatment was carried out for refractory hypoxemia. From December 2016 to October 2017, on the basis of conventional therapy, we explored the use of iNO to treat refractory hypoxemia.

RESULTS

Fifty-three TAAD patients with refractory hypoxemia were enrolled in this study. Twenty-seven patients received conventional treatment (conventional group), while the remaining 26 patients received iNO therapy. The PaO₂/FiO₂ ratio was significantly higher in the iNO group after treatment than in the conventional group when analyzed over the entire 72 hours. The duration of invasive mechanical ventilation was significantly reduced in the iNO group (69.19 vs. 104.56 hours; P=0.003). Other outcomes, such as mortality (3.85% vs. 7.41%, P=1.000), intensive care unit (ICU) duration (9.88 vs. 12.36 days, P=0.059) and hospital stay (16.88 vs. 20.76 days, P=0.060), were not significantly different between the two groups.

CONCLUSIONS

iNO therapy might play an ameliorative role in patients with refractory hypoxemia after surgical reconstruction for TAAD. This therapy may lead to sustained improvement in oxygenation and reduce the duration of invasive mechanical ventilation.

Nitric Oxide in Cardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

To investigate the efficacy and safety of perioperative administration of nitric oxide in cardiac surgery.

DESIGN

Meta-analysis of randomized controlled trials (RCTs).

PARTICIPANTS

Cardiac surgery patients.

INTERVENTIONS

A search of Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and MEDLINE for RCTs that compared nitric oxide with placebo or other comparators.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was intensive care unit (ICU) stay, and secondary outcomes were mortality, duration of mechanical ventilation, and reduction of mean pulmonary artery pressure. The study included 18 RCTs comprising 958 patients. The authors calculated the pooled odds ratio (OR) and the mean difference (MD) with random-effects model. Quantitative synthesis of data demonstrated a clinically negligible reduction in the length of ICU stay (MD -0.38 days, confidence interval CI [-0.65 to -0.11]; p = 0.005) and mechanical ventilation duration (MD -4.81 hours, CI [-7.79 to -1.83]; p = 0.002) compared with all control interventions with no benefit on mortality.

CONCLUSIONS

Perioperative delivery of inhaled nitric oxide resulted to be of no or minimal benefit in patients with pulmonary hypertension undergoing cardiac surgery. Large, randomized trials are needed to further assess its effect on major clinical outcomes and its cost-effectiveness.

Anesthesia for Lung Transplantation

Perioperative management of patients undergoing lung transplantation is challenging and requires constant communication among the surgical, anesthesia, perfusion, and nursing teams. Although all aspects of anesthetic management are important, certain intraoperative strategies (mechanical ventilation, fluid management, extracorporeal mechanical support deployment) have tremendous impact on the subsequent evolution of the lung transplant recipient, especially with respect to allograft function, and should be carefully considered. This review highlights some of the intraoperative anesthetic challenges and opportunities during lung transplantation.

Cardiac Transplant Postoperative Management and Care

Heart failure impacts a multitude of individuals each year. Treatment is based on the progression of the disease and severity of symptoms. Cardiac transplant is the gold standard treatment of advanced heart failure, although the availability of organs limits the number of transplants received each year. Postoperative care and monitoring for cardiac transplant is complex and requires specialized nurses and providers at transplant centers for successful outcomes. This article outlines cardiac transplant from preoperative care through transplant, as well as posttransplant monitoring and care including discharge. Special attention is focused on management in the intensive care unit setting and potential complications that can occur in the immediate postoperative period. Interventions for potential complications are also highlighted.

Inhaled nitric oxide and the risk of renal dysfunction in patients with acute respiratory distress syndrome: a propensity-matched cohort study

Background

Inhaled nitric oxide (iNO) is a rescue therapy for severe hypoxemia in patients with acute respiratory distress syndrome (ARDS). Pooled data from clinical trials have signaled a renal safety warning for iNO therapy, but the significance of these findings in daily clinical practice is unclear. We used primary data to evaluate the risk of iNO-associated renal dysfunction in patients with ARDS.

Methods

We conducted a cohort study using data from a tertiary teaching hospital to evaluate the risk of incident renal replacement therapy (RRT) in iNO users compared with that of non-users. Propensity score matching and competing-risks regression were used for data analysis. Residual confounding was assessed by means of a rule-out approach. We also evaluated effect modification by pre-specified factors using stratified analysis.

Results

We identified 547 patients with ARDS, including 216 iNO users and 331 non-users. At study entry, 313 (57.2%) patients had moderate ARDS and 234 (42.8%) had severe ARDS. The mean patient age was 63 ± 17 years. The crude hazard ratio of the need for RRT in iNO users compared with non-users was 2.23 (95% CI, 1.61–3.09, p < 0.001). After propensity score matching, there were 151 iNO users matched to 151 non-users. The adjusted hazard ratio was 1.59 (95% CI, 1.08–2.34, p = 0.02). In the stratified analysis, we found that older aged patients (≥65 years) were more susceptible to iNO-associated kidney injury than younger patients (p = 0.05).

Conclusions

This study showed that iNO substantially increased the risk of renal dysfunction in patients with ARDS. Older aged patients were especially susceptible to this adverse event.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1566-0) contains supplementary material, which is available to authorized users.

L-citrulline improves splanchnic perfusion and reduces gut injury during exercise

PURPOSE

Splanchnic hypoperfusion is a physiological phenomenon during strenuous exercise. It has been associated with gastrointestinal symptoms and intestinal injury and may hamper athletic performance. We hypothesized that L-citrulline supplementation improves splanchnic perfusion and decreases intestinal injury by enhancing arginine availability. The aim of this study was to determine the effect of L-citrulline intake on splanchnic perfusion, intestinal injury, and barrier function during exercise.

METHODS

In this randomized, double-blind crossover study, 10 men cycled for 60 min at 70% of their maximum workload after L-citrulline (10 g) or placebo (L-alanine) intake. Splanchnic perfusion was assessed using gastric air tonometry. Sublingual microcirculation was evaluated by sidestream dark field imaging. Plasma amino acid levels and intestinal fatty acid binding protein concentrations, reflecting enterocyte damage, were assessed every 10 min. Urinary excretion of sugar probes was measured to evaluate intestinal permeability changes.

RESULTS

Oral L-citrulline supplementation enhanced plasma citrulline (1840.3 ± 142.3 µM) and arginine levels (238.5 ± 9.1 µM) compared with that in placebo (45.7 ± 4.8 µM and 101.5 ± 6.1 µM, respectively, P < 0.0001), resulting in increased arginine availability. Splanchnic hypoperfusion was prevented during exercise after L-citrulline ingestion (reflected by unaltered gapg-apCO2 levels), whereas gapg-apCO2 increased with placebo treatment (P < 0.01). Accordingly, L-citrulline intake resulted in an increased number of perfused small sublingual vessels compared with that in placebo (7.8 ± 6.0 vs -2.0 ± 2.4, P = 0.06). Furthermore, plasma intestinal fatty acid binding protein levels were attenuated during exercise after L-citrulline supplementation compared with that in placebo (AUC0-60 min, -185% ± 506% vs 1318% ± 553%, P < 0.01). No significant differences were observed for intestinal permeability.

CONCLUSIONS

Pre-exercise L-citrulline intake preserves splanchnic perfusion and attenuates intestinal injury during exercise in athletes compared with placebo, probably by enhancing arginine availability. These results suggest that oral L-citrulline supplementation is a promising intervention to combat splanchnic hypoperfusion-induced intestinal compromise.

Brazilian recommendations of mechanical ventilation 2013. Part I

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumonia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.

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.

Pulmonary Hypertension in the Intensive Care Unit

Pulmonary hypertension occurs as the result of disease processes increasing pressure within the pulmonary circulation, eventually leading to right ventricular failure. Patients may become critically ill from complications of pulmonary hypertension and right ventricular failure or may develop pulmonary hypertension as the result of critical illness. Diagnostic testing should evaluate for common causes such as left heart failure, hypoxemic lung disease and pulmonary embolism. Relatively few patients with pulmonary hypertension encountered in clinical practice require specific pharmacologic treatment of pulmonary hypertension targeting the pulmonary vasculature. Management of right ventricular failure involves optimization of preload, maintenance of systemic blood pressure and augmentation of inotropy to restore systemic perfusion. Selected patients may require pharmacologic therapy to reduce right ventricular afterload by directly targeting the pulmonary vasculature, but only after excluding elevated left heart filling pressures and confirming increased pulmonary vascular resistance. Critically-ill patients with pulmonary hypertension remain at high risk of adverse outcomes, requiring a diligent and thoughtful approach to diagnosis and treatment.

Brazilian recommendations of mechanical ventilation 2013. Part I

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumologia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.

Perioperative pharmacological management of pulmonary hypertensive crisis during congenital heart surgery

Pulmonary hypertensive crisis is an important cause of morbidity and mortality in patients with pulmonary arterial hypertension secondary to congenital heart disease (PAH-CHD) who require cardiac surgery. At present, prevention and management of perioperative pulmonary hypertensive crisis is aimed at optimizing cardiopulmonary interactions by targeting prostacyclin, endothelin, and nitric oxide signaling pathways within the pulmonary circulation with various pharmacological agents. This review is aimed at familiarizing the practitioner with the current pharmacological treatment for dealing with perioperative pulmonary hypertensive crisis in PAH-CHD patients. Given the life-threatening complications associated with pulmonary hypertensive crisis, proper perioperative planning can help anticipate cardiopulmonary complications and optimize surgical outcomes in this patient population.

Pharmacological interventions in acute respiratory distress syndrome

Pharmacological interventions are commonly considered in acute respiratory distress syndrome (ARDS) patients. Inhaled nitric oxide (iNO) and neuromuscular blockers (NMBs) are used in patients with severe hypoxemia. No outcome benefit has been observed with the systematic use of iNO. However, a sometimes important improvement in oxygenation can occur shortly after starting administration. Therefore, its ease of use and its good tolerance justify iNO optionally combined with almitirne as a rescue therapy on a trial basis. Recent data from the literature support the use of a 48-h infusion of NMBs in patients with a PaO2 to FiO2 ratio <120 mmHg. No strong evidence exists on the increase of ICU-acquired paresis after a short course of NMBs. Fluid management with the goal to obtain zero fluid balance in ARDS patients without shock or renal failure significantly increases the number of days without mechanical ventilation. On the other hand, patients with hemodynamic failure must receive early and adapted fluid resuscitation. Liberal and conservative fluid strategies therefore are complementary and should ideally follow each other in time in the same patient whose hemodynamic state progressively stabilizes. At present, albumin treatment does not appear to be justified for limitation of pulmonary edema and respiratory morbidity. Aerosolized β2-agonists do not improve outcome in patients with ARDS and one study strongly suggests that intravenous salbutamol may worsen outcome in those patients. The early use of high doses of corticosteroids for the prevention of ARDS in septic shock patients or in patients with confirmed ARDS significantly reduced the duration of mechanical ventilation but had no effect or even increased mortality. In patients with persistent ARDS after 7 to 28 days, a randomized trial showed no reduction in mortality with moderate doses of corticosteroids but an increased PaO2 to FiO2 ratio and thoracopulmonary compliance were found, as well as shorter durations of mechanical ventilation and of ICU stay. Conflicting data exist on the interest of low doses of corticosteroids (200 mg/day of hydrocortisone) in ARDS patients. In the context of a persistent ARDS with histological proof of fibroproliferation, a corticosteroid treatment with a progressive decrease of doses can be proposed.

Distant effects of nitric oxide inhalation in lavage-induced lung injury in anaesthetised pigs

BACKGROUND

Inhalation of nitric oxide (INO) exerts both local and distant effects. INO in healthy pigs causes down-regulation of endogenous nitric oxide (NO) production and vasoconstriction in lung regions not reached by INO, especially in hypoxic regions, which augments hypoxic pulmonary vasoconstriction. In contrast, in pigs with endotoxemia-induced lung injury, INO causes increased NO production in lung regions not reached by INO. The aim of this study was to investigate whether INO exerts distant effects in surfactant-depleted lungs.

METHODS

Twelve pigs were anaesthetised, and the left lower lobe (LLL) was separately ventilated. Lavage injury was induced in all lung regions, except the LLL. In six pigs, 40 ppm INO was given to the LLL (INO group), and the effects on endogenous NO production and blood flow in the lavage-injured lung regions were studied. Six pigs served as a control group. NO concentration in exhaled air (ENO), NO synthase (NOS) activity and cyclic guanosine monophosphate (cGMP) in lung tissue, and regional pulmonary blood flow were measured.

RESULTS

The calcium (Ca(2+) )-dependent NOS activity was lower (P < 0.05) in the lavage-injured lung regions in the INO group than in the control group. There were no measurable differences between the groups for Ca(2+) -independent NOS activity, cGMP, ENO, or regional pulmonary blood flow.

CONCLUSIONS

Regional INO did not increase endogenous NO production in lavage-injured lung regions not directly reached by INO, but instead down-regulated the constitutive calcium-dependent nitric oxide synthase activity, indicating that NO may inhibit its own synthesis.

Pulmonary hemodynamic responses to inhaled NO in chronic heart failure depend on PDE5 G(-1142)T polymorphism

To evaluate the vasoconstrictor component of PH in CHF by investigating the hemodynamic response to inhaled nitric oxide (iNO) and to determine whether this response was influenced by the phosphodiesterase 5 gene (PDE5) G(1142)T polymorphism. CHF patients underwent right heart catheterization at rest and after 20 ppm of iNO and plasma cGMP and PDE5 G(1142)T polymorphism determinations. Of the 72 included CHF patients (mean age, 53±1 years; mean left ventricular ejection fraction, 29±1%; and mean pulmonary artery pressure, 25.5±1.3 mmHg), 54% had ischemic heart disease. Proportions of patients with the TT, GT, and GG genotypes were 39%, 42% and 19% respectively. Baseline hemodynamic characteristics were not significantly different across PDE5 genotype groups, although pulmonary capillary wedge pressure (PCWP) tended to be lower in the TT group (P=0.09). Baseline plasma cGMP levels were significantly lower in the TT than in the GG and GT patients. With iNO, PVR diminished in TT (-33%) but not GG (-1.6%) or GT (0%) patients (P=0.002); and PCWP increased more in TT than in GT (P<0.05) or GG (P<0.003) patients. The PDE5 G(-1142) polymorphism is therefore a major contributor to the iNO-induced PVR decrease in CHF.

Current pathophysiological concepts and management of pulmonary hypertension

Pulmonary hypertension (PH), increasingly recognized as a major health burden, remains underdiagnosed due mainly to the unspecific symptoms. Pulmonary arterial hypertension (PAH) has been extensively investigated. Pathophysiological knowledge derives mostly from experimental models. Paradoxically, common non-PAH PH forms remain largely unexplored. Drugs targeting lung vascular tonus became available during the last two decades, notwithstanding the disease progresses in many patients. The aim of this review is to summarize recent advances in epidemiology, pathophysiology and management with particular focus on associated myocardial and systemic compromise and experimental therapeutic possibilities. PAH, currently viewed as a panvasculopathy, is due to a crosstalk between endothelial and smooth muscle cells, inflammatory activation and altered subcellular pathways. Cardiac cachexia and right ventricular compromise are fundamental determinants of PH prognosis. Combined vasodilator therapy is already mainstay for refractory cases, but drugs directed at these new pathophysiological pathways may constitute a significant advance.

Inhaled nitric oxide plus iloprost in the setting of post-left assist device right heart dysfunction

BACKGROUND

Pulmonary hypertension and right ventricular (RV) dysfunction may complicate the implantation of a left ventricular assist device (LVAD). We examined whether inhaled vasodilators can sufficiently reduce RV afterload, avoiding the need for temporary RV mechanical support.

METHODS

The study includes 7 patients with RV dysfunction after LVAD insertion. Treatment consisted of inotropes, inhaled nitric oxide (10 ppm), and iloprost (10 μg) in repeated doses. Full hemodynamic profile was obtained before inhalation, during administration of inhaled NO alone (before and after iloprost), as well as after the first two doses of inhaled iloprost. Tricuspid annular velocity was estimated at baseline and before and after adding iloprost.

RESULTS

There was a statistically significant reduction in pulmonary vascular resistance (PVR), mean pulmonary artery pressure (MPAP), RV systolic pressure, and pulmonary capillary wedge pressure, and a considerable increase in LVAD flow, LV flow rate index, and tricuspid annular velocity at all points of evaluation versus baseline. By the end of the protocol, MPAP/mean systemic arterial pressure, and PVR/systemic vascular resistance ratios were reduced by 0.17±0.03 (95% confidence interval, 0.10 to 0.25, p=0.001) and 0.12±0.025 (95% confidence interval, 0.06 to 0.18; p=0.003), respectively. The tricuspid annular velocity increased by 2.3±0.18 cm/s (95% confidence interval, 1.83 to 2.73 cm/s; p<0.001). Pairwise comparisons before and after iloprost showed an important decrease in PVR (p=0.022), MPAP (p=0.001), pulmonary capillary wedge pressure (p=0.002), and RV systolic pressure (p<0.001), and a rise in tricuspid annular velocity (p=0.008).

CONCLUSIONS

Inhaled vasodilators mainly affected the pulmonary vasculature. Combination treatment with inhaled NO and iloprost sufficiently decreased PVR and MPAP on the basis of an additive effect, improved RV function, and avoided the need for RV assist device.

'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.

Successful treatment of acute respiratory distress syndrome after hysterectomy for life-threatening atonic bleeding by inhaled nitric oxide

We report a case of a 33-year-old female who developed severe acute respiratory distress syndrome (ARDS) after emergency hysterectomy for life-threatening atonic bleeding. A marked decline in pulmonary oxygenation was observed during the surgery, which led to a diagnosis of ARDS. Following admission to the intensive care unit, hypoxia became critical, with a PaO(2)/F(I)O(2) value of 52 even after recruitment maneuvers. Inhaled nitric oxide (NO 10 ppm) was administered to the patient as a rescue treatment, resulting in a gradual but dramatic improvement in pulmonary oxygenation. Although several randomized trials have failed to confirm the beneficial effects of NO on morbidity in patients with ARDS, NO administration is worth consideration as treatment prior to invasive treatments, such as extracorporeal membrane oxygenation, for patients with acute lung injury/ARDS.

A critical appraisal of the quality of critical care pharmacotherapy clinical practice guidelines and their strength of recommendations

OBJECTIVE

Clinical practice guideline (CPG) quality assessment is important before applying their recommendations. Determining whether recommendation strength is consistent with supporting quality of evidence is also essential. We aimed to determine quality of critical care pharmacotherapy CPGs and to assess whether high quality evidence supports strong pharmacotherapy recommendations.

METHODS

MEDLINE (1966-February 2008), EMBASE (1980-February 2008), National Guideline Clearinghouse (February 2008) and personal files were searched to identify CPGs. Four appraisers evaluated each guideline using the appraisal of guidelines, research and evaluation (AGREE) instrument. AGREE assesses 23 items in six domains that include scope/purpose, stakeholder involvement, rigor of development, clarity, applicability and editorial independence. Standardized domain scores (0-100%) were determined to decide whether to recommend a guideline for use. One appraiser extracted strong pharmacotherapy recommendations and supporting evidence quality.

RESULTS

Twenty-four CPGs were included. Standardized domain scores were clarity [69% (95% confidence interval (CI) 62-76%)], scope/purpose [62% (95% CI 55-68%)], rigor of development [51% (95% CI 42-60%)], editorial independence [39% (95% CI 26-52%)], stakeholder involvement [32% (95% CI 26-37%)] and applicability [19% (95% CI 12-26%)]. The proportion of guidelines that could be strongly recommended, recommended with alterations and not recommended was 25, 37.5 and 37.5%, respectively. High quality evidence supported 36% of strong pharmacotherapy recommendations.

CONCLUSION

Variation in AGREE domain scores explain why one-third of critical care pharmacotherapy CPGs cannot be recommended. Only one-third of strong pharmacotherapy recommendations were supported by high quality evidence. We recommend appraisal of guideline quality and the caliber of supporting evidence prior to applying recommendations.

S3 guidelines for intensive care in cardiac surgery patients: hemodynamic monitoring and cardiocirculary system

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefässchirurgie, DGTHG) and the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin, DGAI) made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess the available monitoring methods with regard to indication, procedures, predication, limits, contraindications and risks for use. The differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilatators, inodilatators and calcium sensitizers and the use of intra-aortic balloon pumps will also be addressed. The guideline has been developed following the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).