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

Current Overview of the Biology and Pharmacology in Sugen/Hypoxia-Induced Pulmonary Hypertension in Rats

The Sugen 5416/hypoxia (Su/Hx) rat model of pulmonary arterial hypertension (PAH) demonstrates most of the distinguishing features of PAH in humans, including increased wall thickness and obstruction of the small pulmonary arteries along with plexiform lesion formation. Recently, significant advancement has been made describing the epidemiology, genomics, biochemistry, physiology, and pharmacology in Su/Hx challenge in rats. For example, there are differences in the overall reactivity to Su/Hx challenge in different rat strains and only female rats respond to estrogen treatments. These conditions are also encountered in human subjects with PAH. Also, there is a good translation in both the biochemical and metabolic pathways in the pulmonary vasculature and right heart between Su/Hx rats and humans, particularly during the transition from the adaptive to the nonadaptive phase of right heart failure. Noninvasive techniques such as echocardiography and magnetic resonance imaging have recently been used to evaluate the progression of the pulmonary vascular and cardiac hemodynamics, which are important parameters to monitor the efficacy of drug treatment over time. From a pharmacological perspective, most of the compounds approved clinically for the treatment of PAH are efficacious in Su/Hx rats. Several compounds that show efficacy in Su/Hx rats have advanced into phase II/phase III studies in humans with positive results. Results from these drug trials, if successful, will provide additional treatment options for patients with PAH and will also further validate the excellent translation that currently exists between Su/Hx rats and the human PAH condition.

Targeted Neonatal Echocardiography in the Management of Neonatal Pulmonary Hypertension

Pulmonary hypertension (PH) in neonates, originating from a range of disease states with heterogeneous underlying pathophysiology, is associated with significant morbidity and mortality. Although the final common pathway is a state of high right ventricular afterload leading to compromised cardiac output, multiple hemodynamic phenotypes exist in acute and chronic PH, for which cardiorespiratory treatment strategies differ. Comprehensive appraisal of pulmonary pressure, pulmonary vascular resistance, cardiac function, pulmonary and systemic blood flow, and extrapulmonary shunts facilitates delivery of individualized cardiovascular therapies in affected newborns.

Advances in the research of sulfur dioxide and pulmonary hypertension

Pulmonary hypertension (PH) is a fatal disease caused by progressive pulmonary vascular remodeling (PVR). Currently, the mechanisms underlying the occurrence and progression of PVR remain unclear, and effective therapeutic approaches to reverse PVR and PH are lacking. Since the beginning of the 21st century, the endogenous sulfur dioxide (SO2)/aspartate transaminase system has emerged as a novel research focus in the fields of PH and PVR. As a gaseous signaling molecule, SO2 metabolism is tightly regulated in the pulmonary vasculature and is associated with the development of PH as it is involved in the regulation of pathological and physiological activities, such as pulmonary vascular cellular inflammation, proliferation and collagen metabolism, to exert a protective effect against PH. In this review, we present an overview of the studies conducted to date that have provided a theoretical basis for the development of SO2-related drug to inhibit or reverse PVR and effectively treat PH-related diseases.

Reducing O2 sensitivity in electrochemical nitric oxide releasing catheters: An O2-tolerant copper(II)-ligand nitrite reduction catalyst and a glucose oxidase catheter coating

Electrocatalytic nitric oxide (NO) generation from nitrite (NO₂^-) within a single lumen of a dual-lumen catheter using Cu^II-ligand (Cu^II-L) mediators have been successful at demonstrating NO's potent antimicrobial and antithrombotic properties to reduce bacterial counts and mitigate clotting under low oxygen conditions (e.g., venous blood). Under more aerobic conditions, the O₂ sensitivity of the Cu(II)-ligand catalysts and the reaction of O₂ (highly soluble in the catheter material) with the NO diffusing through the outer walls of the catheters results in a large decreases in NO fluxes from the surfaces of the catheters, reducing the utility of this approach. Herein, we describe a new more O₂-tolerant Cu^II-L catalyst, [Cu(BEPA-EtSO₃)(OTf)], as well as a potentially useful immobilized glucose oxidase enzyme-coating approach that greatly reduces the NO reactivity with oxygen as the NO partitions and diffuses through the catheter material. Results from this work demonstrate that very effective NO fluxes (>1*10^-10 mol min^-1 cm^-2) from a single-lumen silicone rubber catheter can be achieved in the presence of up to 10% O₂ saturated solutions.

Pharmacological treatment of cardiogenic shock - A state of the art review

Cardiogenic shock is a clinical syndrome of impaired tissue perfusion caused by primary cardiac dysfunction and inadequate cardiac output. It represents one of the most lethal clinical conditions in intensive care medicine with mortality >40%. Management of different clinical presentations of cardiogenic shock includes guidance of cardiac preload, afterload, heart rate and contractility by differential pharmacological modulation of volume, systemic and pulmonary vascular resistance and cardiac output besides reversing the triggering cause. Data from large registries and randomized controlled trials on optimal diagnostic guidance as well as choice of pharmacological agents has accrued significantly in recent years. This state-of-the-art review summarizes the basic concepts of cardiogenic shock, the diagnostic work-up and currently available evidence and guideline recommendations on pharmacological treatment of cardiogenic shock.

How to diagnose and treat acute pulmonary hypertension when you have no cardiology support

Acute pulmonary hypertension (aPH) is a complex, physiology-driven disorder that causes critical illness in newborns, the hallmark of which is elevated pressure in the pulmonary vascular bed. Several underlying hemodynamic phenotypes exist, including classic arterial aPH with resistance-driven elevations in pulmonary arterial pressure (PAP), alongside flow-driven aPH from left-to-right shunt lesions, and primary left ventricular dysfunction with pulmonary venous hypertension and elevated left atrial pressure. Targeted neonatal echocardiography (TnECHO) is an important tool for evaluation of hemodynamics in aPH and is highly useful for evaluating modulators of disease and targeting cardiovascular therapy. The diagnostic approach to aPH includes confirmation of elevation of PAP, evaluation of the cause and exclusion of structural cardiac disease, assessment of the response of the myocardium to adverse loading conditions, and appraisal of the adequacy of systemic blood flow. Therapeutic goals include support of right ventricular (RV) function, RV afterload reduction, and selection of cardiotropic agents that support underlying pathophysiology without adverse effects on heart rate or pulmonary vascular resistance in addition to routine supportive intensive care. Training programs for TnECHO exist across multiple jurisdictions and strong correlation with pediatric cardiology assessment has been demonstrated. Future directions include adapting TnECHO training with a greater focus on achieving competency, and further research into the role of the modality in providing individualized cardiovascular care for patients with heterogenous underlying physiology, and its effect on key neonatal outcomes.

Electrochemical Generation of Nitric Oxide for Medical Applications

Over the past 30 years, the significance of nitric oxide (NO) has become increasingly apparent in mammalian physiology. It is biosynthesized by three isoforms of nitric oxide synthases (NOS): neuronal (nNOS), endothelial (eNOS), and inducible (iNOS). Neuronal and eNOS both produce low levels of NO (nM) as a signaling agent and vasodilator, respectively. Inducible (iNOS) is present in activated macrophages at sites of infection to generate acutely toxic (μM) levels of NO as part of the mammalian immune defense mechanism. These discoveries have led to numerous animal and clinical studies to evaluate the potential therapeutic utility of NO in various medical operations/treatments, primarily using NO gas (via gas-cylinders) as the NO source. In this review, we focus specifically on recent advances in the electrochemical generation of NO (E-NOgen) as an alternative means to generate NO from cheap and inert sources, and the fabrication and testing of biomedical devices that utilize E-NOgen to controllably generate NO for medical applications.

Inhaled nitric oxide for treating pain crises in people with sickle cell disease

BACKGROUND

In people with sickle cell disease, sickled red blood cells cause the occlusion of small blood vessels, which presents as episodes of severe pain known as pain crises or vaso-occlusive crises. The pain can occur in the bones, chest, or other parts of the body, and may last several hours to days. Pain relief during crises includes both pharmacologic and non-pharmacologic treatments. The efficacy of inhaled nitric oxide in pain crises has been a subject of controversy; hypotheses have been made suggesting a beneficial response due to its vasodilator properties, yet no conclusive evidence has been presented. This review aimed to evaluate the available randomised controlled studies addressing this topic.

OBJECTIVES

To capture the body of evidence evaluating the efficacy and safety of the use of inhaled nitric oxide in treating pain crises in people with sickle cell disease, and to assess the relevance, robustness, and validity of the treatment to better guide medical practice in the fields of haematology and palliative care (since the recent literature seems to favour the involvement of palliative care for such people).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register. We searched for unpublished work in the abstract books of the European Haematology Association conference, the American Society of Hematology conference, the British Society for Haematology Annual Scientific Meeting, the Caribbean Health Research Council Meetings, and the National Sickle Cell Disease Program Annual Meeting. The most recent search was conducted on 1 September 2021. We also searched ongoing study registries on 19 November 2021.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing inhaled nitric oxide with placebo for treating pain crises in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data (including adverse event data), with any disagreements resolved by consulting a third review author. When the data were not reported in the text, we attempted to extract the data from available tables or figures. We contacted trial authors for additional information. We assessed the certainty of the evidence using the GRADE criteria.

MAIN RESULTS

We included three trials involving a total of 188 participants in the review. There were equal numbers of males and females. Most participants were adults, although one small trial was conducted in a children's hospital and recruited children over the age of 10 years. All three parallel trials compared inhaled nitric oxygen (80 parts per million (ppm)) to placebo (nitrogen gas mixed with oxygen or room air) for four hours; one trial continued administering nitric oxide (40 ppm) for a further four hours. This extended trial had an overall low risk of bias; however, we had concerns about risk of bias for the remaining two trials due to their small sample size, and additionally a high risk of bias due to financial conflicts of interest in one of these smaller trials. We were only able to analyse some limited data from the eight-hour trial, reporting the remaining results narratively. Evidence from one trial (150 participants) suggested that inhaled nitric oxide may not reduce the time to pain resolution: inhaled nitric oxide median 73.0 hours (95% confidence interval (CI) 46.0 to 91.0) and with placebo median 65.5 hours (95% CI 48.1 to 84.0) (low-certainty evidence). No trial reported on the duration of the initial pain crisis. Only one large trial reported on the frequency of pain crises in the follow-up period and found there may be little or no difference between the inhaled nitric oxide and placebo groups for return to the emergency department (risk ratio (RR) 0.73, 95% CI 0.31 to 1.71) and rehospitalisation (RR 0.53, 95% CI 0.25 to 1.11) (150 participants; low-certainty evidence). There may be little or no difference between treatment and placebo in terms of reduction in pain score at any time point up to eight hours (150 participants). The two smaller trials reported a beneficial effect of inhaled nitric oxide in reducing the visual analogue pain score after four hours of the intervention. Analgesic use was reported not to differ greatly between the inhaled nitric oxide group and placebo group in any of the three trials, but no analysable data were provided. Two trials reported the median duration of hospitalisation: in the largest trial the placebo group had the shorter duration, whilst in the second smaller (paediatric) trial hospitalisation was shorter in the treatment group. Only the largest trial (150 participants) reported serious adverse events, with no increase in the inhaled nitric oxide group during or after the intervention compared to the control group (acute chest syndrome occurred in 5 out of 75 participants from each group, pyrexia in 1 out of 75 participants from each group, and dysphagia and a drop in haemoglobin were each reported in 1 out of 75 participants in the inhaled nitric oxide group) (low-certainty evidence).

AUTHORS' CONCLUSIONS

The currently available evidence is insufficient to determine the effects (benefits or harms) of using inhaled nitric oxide to treat pain (vaso-occlusive) crises in people with sickle cell disease. Large-scale, long-term trials are needed to provide more robust data in this area. Patient-important outcomes (e.g. measures of pain and time to pain resolution and amounts of analgesics used), as well as use of healthcare services, should be measured and reported in a standardised manner.

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.

Right heart failure: A narrative review for emergency clinicians

INTRODUCTION

Right heart failure (RHF) is a clinical syndrome with impaired right ventricular cardiac output due to a variety of etiologies including ischemia, elevated pulmonary arterial pressure, or volume overload. Emergency department (ED) patients with an acute RHF exacerbation can be diagnostically and therapeutically challenging to manage.

OBJECTIVE

This narrative review describes the pathophysiology of right ventricular dysfunction and pulmonary hypertension, the methods to diagnose RHF in the ED, and management strategies.

DISCUSSION

Right ventricular contraction normally occurs against a low pressure, highly compliant pulmonary vascular system. This physiology makes the right ventricle susceptible to acute changes in afterload, which can lead to RHF. Patients with acute RHF may present with an acute illness and have underlying chronic pulmonary hypertension due to left ventricular failure, pulmonary arterial hypertension, chronic lung conditions, thromboemboli, or idiopathic conditions. Patients can present with a variety of symptoms resulting from systemic edema and hemodynamic compromise. Evaluation with electrocardiogram, laboratory analysis, and imaging is necessary to evaluate cardiac function and end organ injury. Management focuses on treating the underlying condition, optimizing oxygenation and ventilation, treating arrhythmias, and understanding the patient's hemodynamics with bedside ultrasound. As RHF patients are preload dependent they may require fluid resuscitation or diuresis. Hypotension should be rapidly addressed with vasopressors. Cardiac contractility can be augmented with inotropes. Efforts should be made to support oxygenation while trying to avoid intubation if possible.

CONCLUSIONS

Emergency clinician understanding of this condition is important to diagnose and treat this life-threatening cardiopulmonary disorder.

Initiation of Inhaled Nitric Oxide by Air Transport Team in Adult COVID-19 Respiratory Failure

The coronavirus disease 2019 (COVID-19) pandemic has caused a significant increase in the volume of critical care flight transports between outlying referral hospitals and tertiary care facilities. Because of the tropism of severe acute respiratory syndrome coronavirus 2, flight crews are often asked to transport mechanically ventilated patients in refractory hypoxemic respiratory failure. The authors present a case series of 5 patients with COVID-19 acute respiratory distress syndrome (ARDS) who were initiated on inhaled nitric oxide (iNO) by the transport team before rotor wing transport and survived the journey in stable or improved condition upon arrival. Previously, no case reports have described adults with COVID-19 ARDS transported after iNO initiation by the transport team. This case series shows the feasibility of iNO initiation by trained air medical transport teams and suggests a short-term stabilizing effect of iNO in patients with ARDS from COVID-19.

Lung function and self-rated symptoms in healthy volunteers after exposure to hydrotreated vegetable oil (HVO) exhaust with and without particles

Background

Diesel engine exhaust causes adverse health effects. Meanwhile, the impact of renewable diesel exhaust, such as hydrotreated vegetable oil (HVO), on human health is less known. Nineteen healthy volunteers were exposed to HVO exhaust for 3 h in a chamber with a double-blind, randomized setup. Exposure scenarios comprised of HVO exhaust from two modern non-road vehicles with 1) no aftertreatment system (‘HVO_PM+NOx’ PM1: 93 µg m⁻³, EC: 54 µg m⁻³, NO: 3.4 ppm, NO₂: 0.6 ppm), 2) an aftertreatment system containing a diesel oxidation catalyst and a diesel particulate filter (‘HVO_NOx’ PM1: ~ 1 µg m⁻³, NO: 2.0 ppm, NO₂: 0.7 ppm) and 3) filtered air (FA) as control. The exposure concentrations were in line with current EU occupational exposure limits (OELs) of NO, NO₂, formaldehyde, polycyclic aromatic hydrocarbons (PAHs), and the future OEL (2023) of elemental carbon (EC). The effect on nasal patency, pulmonary function, and self-rated symptoms were assessed. Calculated predicted lung deposition of HVO exhaust particles was compared to data from an earlier diesel exhaust study.

Results

The average total respiratory tract deposition of PM1 during HVO_PM+NOx was 27 µg h⁻¹. The estimated deposition fraction of HVO PM1 was 40–50% higher compared to diesel exhaust PM1 from an older vehicle (earlier study), due to smaller particle sizes of the HVO_PM+NOx exhaust. Compared to FA, exposure to HVO_PM+NOx and HVO_NOx caused higher incidence of self-reported symptoms (78%, 63%, respectively, vs. 28% for FA, p < 0.03). Especially, exposure to HVO_PM+NOx showed 40–50% higher eye and throat irritation symptoms. Compared to FA, a decrement in nasal patency was found for the HVO_NOx exposures (− 18.1, 95% CI: − 27.3 to − 8.8 L min⁻¹, p < 0.001), and for the HVO_PM+NOx (− 7.4 (− 15.6 to 0.8) L min⁻¹, p = 0.08). Overall, no clinically significant change was indicated in the pulmonary function tests (spirometry, peak expiratory flow, forced oscillation technique).

Conclusion

Short-term exposure to HVO exhaust concentrations corresponding to EU OELs for one workday did not cause adverse pulmonary function changes in healthy subjects. However, an increase in self-rated mild irritation symptoms, and mild decrease in nasal patency after both HVO exposures, may indicate irritative effects from exposure to HVO exhaust from modern non-road vehicles, with and without aftertreatment systems.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00446-7.

Care of the critically ill neonate with hypoxemic respiratory failure and acute pulmonary hypertension: framework for practice based on consensus opinion of neonatal hemodynamics working group

Circulatory transition after birth presents a critical period whereby the pulmonary vascular bed and right ventricle must adapt to rapidly changing loading conditions. Failure of postnatal transition may present as hypoxemic respiratory failure, with disordered pulmonary and systemic blood flow. In this review, we present the biological and clinical contributors to pathophysiology and present a management framework.

Feasibility of non-invasive nitric oxide gas inhalation to prevent endotracheal intubation in patients with acute hypoxemic respiratory failure: A single-centre experience

BACKGROUND

Acute hypoxemic respiratory failure (ARF) is characterized by both lower arterial oxygen and carbon dioxide tensions in the blood. First line treatment for ARF includes oxygen therapy - intially administered non invasively using nasal prongs, high flow nasal cannulae (HFNC) or masks. Invasive mechanical ventilation (IMV) is usually reserved for patients who are unable to maintain their airway, those with worsening hypoxemia, or those who develop respiratory muscle fatigue and consequent hypercapnia. Inhaled nitric oxide (iNO) gas is known to improve oxygenation in patients with ARF by manipulating ventilation-perfusion matching. Addition of iNO may potentially alleviate the need for IMV in selected patients.

CASE SUMMARY

In this article we report our preliminary experience of using HFNC to deliver oxygen and nitric oxide gas in patients with hypoxemic ARF as a strategy to potentially avoid IMV in selected patients.

CONCLUSION

This article demonstrates the feasibility of this technique based on our experience of patients with hypoxemic ARF and generates hypothesis for future studies.

Evaluation of Inhaled Alprostadil in Hospitalized Adult Patients

BACKGROUND

Intermittent inhaled alprostadil (iPGE₁) may be a viable alternative to inhaled nitric oxide or epoprostenol for management of right ventricular failure, pulmonary hypertension (pHTN) or acute respiratory distress syndrome (ARDS). However, limited evidence exists regarding iPGE₁ use in adults, ideal dosing strategies, or optimal use cases.

OBJECTIVE

To describe the clinical characteristics of patients receiving iPGE₁ and identify specific sub-populations warranting further research.

METHODS

This was a single-center, retrospective, descriptive analysis of inpatients who received at least one dose of iPGE₁. The primary outcome was to describe patient characteristics and alprostadil dosing strategies. Secondary outcomes included changes in respiratory support requirements, hemodynamics, and inotropic/vasoactive use. Outcomes were stratified and compared based on primary therapeutic indication (cardiac or pulmonary).

RESULTS

Fifty-four patients received iPGE₁ 40 (75%) for pulmonary (pHTN or ARDS) and 14 (25%) for cardiac indications. There was no difference between indications in the number of patients de-escalated from level of respiratory (53% vs 57%, P = 0.76), inotropic (70% vs 57%, P = 0.39), or vasopressor support (78% vs 57%, P = 0.17). Furthermore, there was no significant improvement in cardiopulmonary parameters at multiple time intervals after iPGE₁ initiation.

CONCLUSION AND RELEVANCE

This is the largest study to date on the use of intermittent iPGE₁ in adults. Alprostadil was safely utilized in novel populations; however, efficacy as evaluated by clinical or surrogate endpoints could not be demonstrated and further investigation is needed to determine its potential and optimal place in therapy.

Clinical Outcomes of Critically Ill Patients Using Inhaled Nitric Oxide (iNO) during Intrahospital Transport

Critically ill patients with severe hypoxemia are often treated in the intensive care unit (ICU) with inhaled nitric oxide (iNO). These patients are at higher risk when they require intrahospital transportation. In this study, we collected clinical and laboratory data from 221 patients who were hospitalized in the general ICU and treated with iNO at Soroka Medical Center, Israel, between January 2010 and December 2019. We retrospectively compared the 65 patients who received iNO during intrahospital transportation to the 156 patients who received iNO without transportation. Among critically ill patients who were transported while being administered iNO, only one patient had an adverse event (atrial fibrillation) on transport. We found that maximal iNO dosage during ICU stay, duration of mechanical ventilation, and percent of vasopressor support were the only independent risk factors for ICU mortality in both study groups. No difference in primary outcome of ICU mortality rate was found between the critically ill patients treated with iNO during intrahospital transportation and those who were treated with iNO but not transported during the ICU stay. We anticipate that this study will advise clinical decision-making in the ICU, especially when treating patients who are administered iNO.

Inhaled Nitric Oxide: In Vitro Analysis of Continuous Flow Noninvasive Delivery via Nasal Cannula

BACKGROUND

Inhaled nitric oxide (NO) is most frequently delivered to mechanically ventilated patients in critical care, but it can also be administered noninvasively. The delivered dose and efficiency of continuous flow NO supplied through a nasal cannula has yet to be established. This study aimed to determine the influence of nasal cannula type, supply flow, and breathing pattern on delivered NO using a realistic adult airway replica and lung simulator.

METHODS

Simulated breathing patterns were selected to represent rest, sleep, and light exercise, and were varied to investigate the effects of tidal volume and breathing frequency independently. Supplied gas flows targeted tracheal concentrations at rest of 5 or 20 ppm NO and were supplied with 2 L/min O₂. Three different cannulas were tested. Tracheal NO concentrations and NO mass flow past the trachea were evaluated.

RESULTS

Cannula type had a minor influence on delivered dose. Tracheal NO concentrations differed significantly based on breathing pattern (P < 0.01); for a target NO concentration of 20 ppm at rest, average inhaled NO concentrations were 23.3 ± 0.5 ppm, 36.5 ± 1.4 ppm, and 17.2 ± 0.3 ppm for the rest, sleep, and light exercise breathing patterns, respectively. For the same test conditions, mass flow of NO past the trachea was less sensitive to breathing pattern: 20.3 ± 0.5 mg/h, 19.9 ± 0.8 mg/h, and 24.3 ± 0.4 mg/h for the rest, sleep, and light exercise breathing patterns, respectively. Mass flow and delivery efficiency increased when minute volume increased.

CONCLUSIONS

These results indicate that inhaled NO concentration is strongly influenced by breathing pattern, whereas inhaled NO mass flow is not. NO mass flow may therefore be a useful dose metric for continuous flow delivery via nasal cannula.

Inhaled nitric oxide and acute kidney injury risk: a meta-analysis of randomized controlled trials

Purpose

There are conflicting results as to the effect of inhaled nitric oxide (iNO) therapy on the risk of acute kidney injury (AKI). The aim of this study was to perform a meta-analysis to assess the updated data.

Methods

We systematically searched Web of Science, the Cochrane Library, Wanfang, and PubMed for relevant randomized control trials between database inception and 9/07/2020. Relative risks (RRs) with 95% confidence intervals (CIs) predicting the risk of AKI were extracted to obtain summary estimates using fixed-effects models. The Trim and Fill method was used to evaluate the sensitivity of the results and adjust for publication bias in meta-analysis.

Results

15 randomized controlled studies from 14 articles involving 1853 patients were included in the study. Analyzing the eligible studies we found: (1) iNO therapy significantly increased the risk of AKI in acute respiratory distress syndrome patients (RR 1.55, 95% CI 1.15–2.10, p = 0.004; I² for heterogeneity 0%; P_het = 0.649). (2) The use of iNO was associated with reduced AKI risk in patients undergoing cardiac surgery (RR 0.80, 95% CI 0.64–0.99, p = 0.037; I² for heterogeneity 0%; P_het = 0.528). (3) For organ transplantation recipients, there was no effect of iNO administration on the risk of AKI (RR 0.50, 95% CI 0.16–1.56, p = 0.233; I² for heterogeneity 0%; P_het = 0.842). The Trim and Fill analysis showed that the overall effect of this meta-analysis was stable.

Conclusions

The effect of iNO on AKI risk might be disease-specific. Future RCTs with larger patient populations should aim to validate our findings.

In vitro investigation of the Flusso™ Bypass adapter efficiency upon ventilator circuit disconnect in a clinical simulated environment

Rationale

Mechanically ventilated patients must be disconnected from the ventilator during intra-facility transfers. Intentional and accidental circuit disconnections represent a potential hazard to patients (sudden collapse and re-expansion of the alveoli) as well as to clinical staff (exposure to patient’s unfiltered exhalation). Therefore, avoiding abrupt circuit disconnections could better protect the patient’s health and reduce or eliminate contamination risks around clinical staff.

Objective

The purpose of this in-vitro work was to investigate and evaluate the potential for environmental exposure of Nitric Oxide (NO, as an indicator of any contamination exposure) before and after implementing the novel Flusso™ Bypass adapter during the disconnect procedure of a mechanical ventilator system.

Methods

A mechanical ventilator delivering NO was connected to a breathing simulator with and without the Flusso™ Bypass adapter. The ambient NO concentration was measured when the circuit was briefly disconnected (3 s) during inhalation and exhalation. Both volume and pressure ventilation modes were used.

Measurements and main results

Disconnecting the standard ventilator circuit (pressure-controlled mode) without the Flusso™ Bypass adapter produced higher NO escape to the surroundings (compared with the volume-controlled mode), leading to a longer NO dissipation time. No ambient NO traces were detected when the Flusso™ adapter was used.

Conclusion

The usage of the Flusso™ adapter drastically decreases the unwanted exposure among clinical staff dealing with potentially hazardous airborne biological aerosols emanating from the circuit. Avoiding abrupt disconnection in the ventilator circuit could reduce lung injuries and alveolar over distension and collapse.

Implication of inhaled nitric oxide for the treatment of critically ill COVID-19 patients with pulmonary hypertension

Aims

This study aims to analyse whether inhaled nitric oxide (iNO) was beneficial in the treatment of coronavirus disease 2019 (COVID‐19) patients with pulmonary hypertension.

Methods and results

Five critically ill COVID‐19 patients with pulmonary hypertension designated Cases 1–5 were retrospectively included. Clinical data before and after iNO treatment were serially collected and compared between patients with or without iNO treatment. The five cases experienced pulmonary artery systolic pressure (PASP) elevation (≥50 mmHg) at 30, 24, 33, 23, and 24 days after illness onset (d.a.o), respectively. Cases 1–3 received iNO treatment on the 24th, 13th, and 1st day after the first elevation of PASP, with concentrations varied from 10 to 20 ppm based on the changes of PASP and blood pressure for 10, 9, and 5 days, respectively. Upon iNO treatment, PASP of Cases 1 and 2 returned to normal on the 10th day and 1st day, and maintained between 50 and 58 mmHg in Case 3. Pa0₂/Fi0₂ increased from 88 to 124, 51 to 118, and 146 to 244, respectively. SPO₂ increased from 91% to 97% for Case 1 and maintained a high level above 97% for Case 2. Cardiac function remained normal in the three patients after treatment. Moreover, Cases 1 and 3 survived from severe acute respiratory syndrome coronavirus 2 infection, while Case 2 finally died on the 36th day after the first elevation of PASP due to severe complications. Both cases who did not receive iNO treatment experienced a sudden decrease of PASP and Pa0₂/Fi0₂ due to right heart failure and then died.

Conclusions

Inhaled nitric oxide treatment was beneficial in reducing and stabilizing the PASP and might also reduce the risk of right heart failure in COVID‐19 with pulmonary hypertension.

Inhaled nitric oxide for treating pain crises in people with sickle cell disease

BACKGROUND

In people with sickle cell disease, sickled red blood cells cause the occlusion of small blood vessels which presents as episodes of severe pain known as pain crises or vaso-occlusive crises. The pain can occur in the bones, chest, or other parts of the body, and may last several hours to days. Pain relief during crises includes both pharmacologic and non-pharmacologic treatments. The efficacy of inhaled nitric oxide in pain crises has been a controversial issue and hypotheses have been made suggesting a beneficial response due to its vasodilator properties. Yet no conclusive evidence has been presented.This review aims to evaluate the available randomised controlled studies which address this topic.

OBJECTIVES

To capture the available body of evidence evaluating the efficacy and safety of the use of inhaled nitric oxide in treating pain crises in people with sickle cell disease; and to assess the treatment's relevance, robustness, and validity, in order to better guide medical practice in the fields of haematology and palliative care (since recent literature seems to favour the involvement of palliative care for those people).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. Unpublished work is identified by searching the abstract books of the European Haematology Association conference; the American Society of Hematology conference; the British Society for Haematology Annual Scientific Meeting; the Caribbean Health Research Council Meetings; and the National Sickle Cell Disease Program Annual Meeting.Date of most recent search: 19 September 2019.We also searched ongoing study registries, date of most recent search: 26 September 2019.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing inhaled nitric oxide with placebo, or standardized way of treatment of pain crises in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data (including adverse event data). A third author helped clarify any disagreement. When the data were not reported in the text, we attempted to extract the data from any table or figure available. We contacted trial authors for additional information. We assessed the quality of the evidence using the GRADE criteria MAIN RESULTS: We identified six trials, three of which (188 participants) were eligible for inclusion in the review. There were equal numbers of males and females; and most participants were adults, although one small trial was conducted in a children's hospital and recruited children over the age of 10 years. All three parallel trials compared inhaled nitric oxygen (80 ppm) to placebo (room air) for four hours; one trial continued administering nitric oxide (40 ppm) for a further four hours. This extended trial had an overall low risk of bias; however, in the remaining two trials we had concerns about the risk of bias from the small sample size and additionally a high risk of bias due to financial conflicts of interest in one of these smaller trials. We were only able to analyse some limited data from the eight-hour trial and report the remaining results narratively.The time to pain resolution was only reported in one trial (150 participants), showing there may be little or no difference between the two groups: with inhaled nitric oxide median 73.0 hours (95% confidence interval (CI) 46.0 to 91.0) and with placebo median 65.5 hours (95% CI 48.1 to 84.0) (low-quality evidence). No trial reported on the duration of the initial pain crisis. Only one large trial reported on the frequency of pain crises in the follow-up period and found there may be little or no difference between the inhaled nitric oxide and placebo groups for a return to the ED, risk ratio 0.73 (95% CI 0.31 to 1.71) or for re-hospitalisation, risk ratio 0.53 (95% CI 0.25 to 1.11) (150 participants; low-quality evidence).There may be little or no difference between treatment and placebo in terms of reduction in pain score at any time point up to eight hours (150 participants). The two smaller trials reported a beneficial effect of inhaled nitric oxide in reducing the visual analogue pain score after four hours of the intervention, but these trials were small and limited compared to the first trial.Analgesic use was reported not to differ greatly between the inhaled nitric oxide group and placebo group in any of the three trials, but no analysable data were provided. The median duration of hospitalisation was reported by two trials, in the largest trial the placebo group had the shorter duration and in the second smaller (paediatric) trial hospitalisation was shorter in the treatment group.Only the largest trial (150 participants) reported serious adverse events, with no increase in the inhaled nitric oxide group during or after the intervention compared to the control group (acute chest syndrome occurred in 5 out of 75 participants from each group, pyrexia in 1 out of 75 participants from each group, dysphagia and a drop in haemoglobin were each reported in 1 out of 75 participants in the inhaled nitric oxide group, but not in the placebo group) (low-quality evidence).

AUTHORS' CONCLUSIONS

The currently available trials do not provide sufficient evidence to determine the effects (benefits or harms) of using inhaled nitric oxide to treat pain (vaso-occlusive) crises in people with sickle cell disease. Large-scale, long-term trials are needed to provide more robust data in this area. Patient-important outcomes (e.g. measures of pain and time to pain resolution and amounts of analgesics used), as well as use of healthcare services should be measured and reported in a standardized form.

Pulmonary Edema and Hypoxic Respiratory Failure

OBJECTIVES

The purpose of this chapter is to outline the causes, physiology, pathophysiology, and management strategies for hydrostatic and permeability pulmonary edema and hypoxic respiratory failure.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

The pulmonary parenchyma and vasculature are at high risk in conditions where injury occurs to the lung and or heart. A targeted approach that uses strategies that optimize the particular pathophysiology of the parenchyma and vasculature is required.

Nitric oxide in paediatric respiratory disorders: novel interventions to address associated vascular phenomena?

Nitric oxide (NO) has a significant role in modulating the respiratory system and is being exploited therapeutically. Neonatal respiratory failure can affect around 2% of all live births and is responsible for over one third of all neonatal mortality. Current treatment method with inhaled NO (iNO) has demonstrated great benefits to patients with persistent pulmonary hypertension, bronchopulmonary dysplasia and neonatal respiratory distress syndrome. However, it is not without its drawbacks, which include the need for patients to be attached to mechanical ventilators. Notably, there is also a lack of identification of subgroups amongst abovementioned patients, and homogeneity in powered studies associated with iNO, which is one of the limitations. There are significant developments in drug delivery methods and there is a need to look at alternative or supplementary methods of NO delivery that could reduce current concerns. The addition of NO-independent activators and stimulators, or drugs such as prostaglandins to work in synergy with NO donors might be beneficial. It is of interest to consider such delivery methods within the respiratory system, where controlled release of NO can be introduced whilst minimizing the production of harmful byproducts. This article reviews current therapeutic application of iNO and the state-of-the-art technology methods for sustained delivery of NO that may be adapted and developed to address respiratory disorders. We envisage this perspective would prompt active investigation of such systems for their potential clinical benefit.

SGLT inhibitors attenuate NO-dependent vascular relaxation in the pulmonary artery but not in the coronary artery

Inhibitors of sodium-glucose cotransporter (SGLT)2 are a new class of oral drugs for type 2 diabetic patients that reduce plasma glucose levels by inhibiting renal glucose reabsorption. There is increasing evidence showing the beneficial effect of SGLT2 inhibitors on glucose control; however, less information is available regarding the impact of SGLT2 inhibitors on cardiovascular outcomes. The present study was designed to determine whether SGLT inhibitors regulate vascular relaxation in mouse pulmonary and coronary arteries. Phlorizin (a nonspecific SGLT inhibitor) and canagliflozin (a SGLT2-specific inhibitor) relaxed pulmonary arteries in a dose-dependent manner, but they had little or no effect on coronary arteries. Pretreatment with phlorizin or canagliflozin significantly inhibited sodium nitroprusside (SNP; a nitric oxide donor)-induced vascular relaxation in pulmonary arteries but not in coronary arteries. Phlorizin had no effect on cGMP-dependent relaxation in pulmonary arteries. SNP induced membrane hyperpolarization in human pulmonary artery smooth muscle cells, and pretreatment of cells with phlorizin and canagliflozin attenuated SNP-induced membrane hyperpolarization by decreasing K(+) activities induced by SNP. Contrary to the result observed in ex vivo experiments with SGLT inhibitors, SNP-dependent relaxation in pulmonary arteries was not altered by chronic administration of canagliflozin. On the other hand, canagliflozin administration significantly enhanced SNP-dependent relaxation in coronary arteries in diabetic mice. These data suggest that SGLT inhibitors differentially regulate vascular relaxation depending on the type of arteries, duration of the treatment, and health condition, such as diabetes.

Inhaled nitric oxide therapy for extrapulmonary inflammation

Inhaled nitric oxide (iNO) has been used extensively to treat pulmonary hypertension primarily in newborns. This therapy is a safe and effective therapy to improve the matching between airway ventilation and blood oxygenation. A key conceptual component of iNO therapy is that effects are limited to the pulmonary compartment thereby avoiding unwanted systemic effects. The mechanism underlying this model is that any NO entering the blood stream is rapidly oxidized to nitrate, a relatively inert anion that is excreted. Mediating this oxidation is oxyhemoglobin that becomes oxidized to methemoglobin, accumulation of which is limited by erythrocyte methemoglobin reductase. In this article, we discuss studies that dismiss the notion that once in the blood stream iNO is inactivated and show that a surprising result of iNO therapy is the formation of stable NO-derived products that circulate and can elicit NO-dependent signaling in extra-pulmonary tissues. This pathway has the potential to open up new applications for iNO for treatment of systemic diseases associated with loss of NO signaling.

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.

Effects of pulse-delivered inhaled nitric oxide administration on pulmonary perfusion and arterial oxygenation in dorsally recumbent isoflurane-anesthetized horses

OBJECTIVE

To image the spatial distribution of pulmonary blood flow by means of scintigraphy, evaluate ventilation-perfusion (VA/Q) matching and pulmonary blood shunting (Qs/Qt) by means of the multiple inert gas elimination technique (MIGET), and measure arterial oxygenation and plasma endothelin-1 concentrations before, during, and after pulse-delivered inhaled nitric oxide (PiNO) administration to isoflurane-anesthetized horses in dorsal recumbency.

ANIMALS

3 healthy adult Standardbreds.

PROCEDURES

Nitric oxide was pulsed into the inspired gases in dorsally recumbent isoflurane-anesthetized horses. Assessment of VA/Q matching, Qs/Qt, and Pao2 content was performed by use of the MIGET, and spatial distribution of pulmonary blood flow was measured by perfusion scintigraphy following IV injection of technetium Tc 99m-labeled macroaggregated human albumin before, during, and 30 minutes after cessation of PiNO administration.

RESULTS

During PiNO administration, significant redistribution of blood flow from the dependent regions to the nondependent regions of the lungs was found and was reflected by improvements in VA/Q matching, decreases in Qs/Qt, and increases in Pao2 content, all of which reverted to baseline values at 30 minutes after PiNO administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of PiNO in anesthetized dorsally recumbent horses resulted in redistribution of pulmonary blood flow from dependent atelectatic lung regions to nondependent aerated lung regions. Because hypoxemia is commonly the result of atelectasis in anesthetized dorsally recumbent horses, the addition of nitric oxide to inhaled gases could be used clinically to alleviate hypoxemia in horses during anesthesia.

Inhaled nitric oxide for the brain dead donor with neurogenic pulmonary edema during anesthesia for organ donation: a case report

Neurogenic pulmonary edema (NPE) in brain dead organ donors occurring after an acute central nervous system insult threatens organ preservation of potential organ donors and the outcome of organ donation. Hence the active and immediate management of NPE is critical. In this case, a 50-year-old male was admitted to the intensive care unit (ICU) for organ donation. He was hypoxic due to NPE induced by spontaneous intracerebral hemorrhage and intraventricular hemorrhage. Protective ventilatory management, intermittent recruitment maneuvers, and supportive treatment were maintained in the ICU and the operating room (OR). Despite this management, the hypoxemia worsened after the OR admission. So inhaled nitric oxide (NO) therapy was performed during the operation, and the hypoxic phenomena showed remarkable improvement. The organ retrieval was successfully completed. Therefore, NO inhalation can be helpful in the improvement of hypoxemia caused by NPE in brain dead organ donors during anesthesia for the organ donation.

Current clinical management of pulmonary arterial hypertension

During the past 2 decades, there has been a tremendous evolution in the evaluation and care of patients with pulmonary arterial hypertension (PAH). The introduction of targeted PAH therapy consisting of prostacyclin and its analogs, endothelin antagonists, phosphodiesterase-5 inhibitors, and now a soluble guanylate cyclase activator have increased therapeutic options and potentially reduced morbidity and mortality; yet, none of the current therapies have been curative. Current clinical management of PAH has become more complex given the focus on early diagnosis, an increased number of available therapeutics within each mechanistic class, and the emergence of clinically challenging scenarios such as perioperative care. Efforts to standardize the clinical care of patients with PAH have led to the formation of multidisciplinary PAH tertiary care programs that strive to offer medical care based on peer-reviewed evidence-based, and expert consensus guidelines. Furthermore, these tertiary PAH centers often support clinical and basic science research programs to gain novel insights into the pathogenesis of PAH with the goal to improve the clinical management of this devastating disease. In this article, we discuss the clinical approach and management of PAH from the perspective of a single US-based academic institution. We provide an overview of currently available clinical guidelines and offer some insight into how we approach current controversies in clinical management of certain patient subsets. We conclude with an overview of our program structure and a perspective on research and the role of a tertiary PAH center in contributing new knowledge to the field.

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Intensive care management of pulmonary hypertension

Pulmonary hypertension (PH) in the Intensive Care Unit (ICU) may be due to preexisting pulmonary vascular lung disease, liver disease, or cardiac diseases. PH also may be caused by critical illnesses, such as acute respiratory distress syndrome (ARDS), acute left ventricular dysfunction and pulmonary embolism, or may occur after cardiac or thoracic surgery.

Regardless of the underlying cause of PH, the final common pathway for hemodynamic deterioration and death is RV failure, which is the most challenging aspect of patient management. Therapy is thus aimed at acutely relieving RV overload by decreasing PVR and reversing RV failure with pulmonary vasodilators and inotropes.

A randomized clinical trial testing the anti-inflammatory effects of preemptive inhaled nitric oxide in human liver transplantation

Decreases in endothelial nitric oxide synthase derived nitric oxide (NO) production during liver transplantation promotes injury. We hypothesized that preemptive inhaled NO (iNO) would improve allograft function (primary) and reduce complications post-transplantation (secondary). Patients at two university centers (Center A and B) were randomized to receive placebo (n = 20/center) or iNO (80 ppm, n = 20/center) during the operative phase of liver transplantation. Data were analyzed at set intervals for up to 9-months post-transplantation and compared between groups. Patient characteristics and outcomes were examined with the Mann-Whitney U test, Student t-test, logistic regression, repeated measures ANOVA, and Cox proportional hazards models. Combined and site stratified analyses were performed. MELD scores were significantly higher at Center B (22.5 vs. 19.5, p<0.0001), surgical times were greater at Center B (7.7 vs. 4.5 hrs, p<0.001) and warm ischemia times were greater at Center B (95.4 vs. 69.7 min, p<0.0001). No adverse metabolic or hematologic effects from iNO occurred. iNO enhanced allograft function indexed by liver function tests (Center B, p<0.05; and p<0.03 for ALT with center data combined) and reduced complications at 9-months (Center A and B, p = 0.0062, OR = 0.15, 95% CI (0.04, 0.59)). ICU (p = 0.47) and hospital length of stay (p = 0.49) were not decreased. iNO increased concentrations of nitrate (p<0.001), nitrite (p<0.001) and nitrosylhemoglobin (p<0.001), with nitrite being postulated as a protective mechanism. Mean costs of iNO were $1,020 per transplant. iNO was safe and improved allograft function at one center and trended toward improving allograft function at the other. ClinicalTrials.gov with registry number 00582010 and the following URL:http://clinicaltrials.gov/show/NCT00582010.

Nitric oxide transport in blood: a third gas in the respiratory cycle

The trapping, processing, and delivery of nitric oxide (NO) bioactivity by red blood cells (RBCs) have emerged as a conserved mechanism through which regional blood flow is linked to biochemical cues of perfusion sufficiency. We present here an expanded paradigm for the human respiratory cycle based on the coordinated transport of three gases: NO, O₂, and CO₂. By linking O₂ and NO flux, RBCs couple vessel caliber (and thus blood flow) to O₂ availability in the lung and to O₂ need in the periphery. The elements required for regulated O₂-based signal transduction via controlled NO processing within RBCs are presented herein, including S-nitrosothiol (SNO) synthesis by hemoglobin and O₂-regulated delivery of NO bioactivity (capture, activation, and delivery of NO groups at sites remote from NO synthesis by NO synthase). The role of NO transport in the respiratory cycle at molecular, microcirculatory, and system levels is reviewed. We elucidate the mechanism through which regulated NO transport in blood supports O₂ homeostasis, not only through adaptive regulation of regional systemic blood flow but also by optimizing ventilation-perfusion matching in the lung. Furthermore, we discuss the role of NO transport in the central control of breathing and in baroreceptor control of blood pressure, which subserve O₂ supply to tissue. Additionally, malfunctions of this transport and signaling system that are implicated in a wide array of human pathophysiologies are described. Understanding the (dys)function of NO processing in blood is a prerequisite for the development of novel therapies that target the vasoactive capacities of RBCs.

Drugs to cure avian influenza infection--multiple ways to prevent cell death

New treatments and new drugs for avian influenza virus (AIV) infection are developed continually, but there are still high mortality rates. The main reason may be that not all cell death pathways induced by AIV were blocked by the current therapies. In this review, drugs for AIV and associated acute respiratory distress syndrome (ARDS) are summarized. The roles of antioxidant (vitamin C) and multiple immunomodulators (such as Celecoxib, Mesalazine and Eritoran) are discussed. The clinical care of ARDS may result in ischemia reperfusion injury to poorly ventilated alveolar cells. Cyclosporin A should effectively inhibit this kind of damages and, therefore, may be the key drug for the survival of patients with virus-induced ARDS. Treatment with protease inhibitor Ulinastatin could also protect lysosome integrity after the infection. Through these analyses, a large drug combination is proposed, which may hypothetically greatly reduce the mortality rate.

A review of cardiac transplantation

Perioperative anesthetic management for cardiac transplantation is reviewed. Recent developments in adult cardiac transplantation are noted. This review includes demographics and historical results, recipient and donor selection and evaluation, mechanical circulatory support and heart transplantation techniques, and patient management immediately postimplantation.

Curcumin modulates the inflammatory response and inhibits subsequent fibrosis in a mouse model of viral-induced acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) is a clinical syndrome characterized by diffuse alveolar damage usually secondary to an intense host inflammatory response of the lung to a pulmonary or extrapulmonary infectious or non-infectious insult often leading to the development of intra-alveolar and interstitial fibrosis. Curcumin, the principal curcumoid of the popular Indian spice turmeric, has been demonstrated as an anti-oxidant and anti-inflammatory agent in a broad spectrum of diseases. Using our well-established model of reovirus 1/L-induced acute viral pneumonia, which displays many of the characteristics of the human ALI/ARDS, we evaluated the anti-inflammatory and anti-fibrotic effects of curcumin. Female CBA/J mice were treated with curcumin (50 mg/kg) 5 days prior to intranasal inoculation with 10(7)pfu reovirus 1/L and daily, thereafter. Mice were evaluated for key features associated with ALI/ARDS. Administration of curcumin significantly modulated inflammation and fibrosis, as revealed by histological and biochemical analysis. The expression of IL-6, IL-10, IFNγ, and MCP-1, key chemokines/cytokines implicated in the development of ALI/ARDS, from both the inflammatory infiltrate and whole lung tissue were modulated by curcumin potentially through a reduction in the phosphorylated form of NFκB p65. While the expression of TGFß1 was not modulated by curcumin, TGFß Receptor II, which is required for TGFß signaling, was significantly reduced. In addition, curcumin also significantly inhibited the expression of α-smooth muscle actin and Tenascin-C, key markers of myofibroblast activation. This data strongly supports a role for curcumin in modulating the pathogenesis of viral-induced ALI/ARDS in a pre-clinical model potentially manifested through the alteration of inflammation and myofibroblast differentiation.

Current knowledge of acute lung injury and acute respiratory distress syndrome

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) continues to be a major cause of mortality in adult and pediatric critical care medicine. This article discusses the pulmonary sequelae associated with ALI and ARDS, the support of ARDS with mechanical ventilation, available adjunctive therapies, and experimental therapies currently being tested. It is hoped that further understanding of the fundamental biology, improved identification of the patient's inflammatory state, and application of therapies directed at multiple sites of action may ultimately prove beneficial for patients suffering from ALI/ARDS.

Anesthetic management of the patient with dilated cardiomyopathy undergoing pulmonary resection surgery: a case-based discussion

Interactions between the cardiovascular and respiratory systems are complex and profound. General anesthesia, muscle relaxation, and positive-pressure ventilation all impose physiological effects on cardiovascular function. In patients presenting for pulmonary resection, additional effects resulting from positioning, 1-lung ventilation, surgical procedures, and contraction of the pulmonary vascular bed may impose an additional physiological burden. For most patients with adequate pulmonary and cardiovascular reserve, these effects are well tolerated. However, the cardiothoracic anesthesiologist may be asked to provide anesthetic care for patients with significantly reduced cardiac function who require potentially curative pulmonary resection for lung cancer. These patients present a major perioperative challenge and a thoughtful approach to intraoperative management is required. The authors review a case of a patient with severely impaired biventricular function who presented for elective pulmonary lobectomy in an attempt to effect a curative resection of lung cancer and present a discussion of physiological and pathophysiological considerations for clinical management.

Nitrite and nitrite reductases: from molecular mechanisms to significance in human health and disease

Nitrite, previously considered physiologically irrelevant and a simple end product of endogenous nitric oxide (NO) metabolism, is now envisaged as a reservoir of NO to be activated in response to oxygen (O(2)) depletion. In the first part of this review, we summarize and compare the mechanisms of nitrite-dependent production of NO in selected bacteria and in eukaryotes. Bacterial nitrite reductases, which are copper or heme-containing enzymes, play an important role in the adaptation of pathogens to O(2) limitation and enable microrganisms to survive in the human body. In mammals, reduction of nitrite to NO under hypoxic conditions is carried out in tissues and blood by an array of metalloproteins, including heme-containing proteins and molybdenum enzymes. In humans, tissues play a more important role in nitrite reduction, not only because most tissues produce more NO than blood, but also because deoxyhemoglobin efficiently scavenges NO in blood. In the second part of the review, we outline the significance of nitrite in human health and disease and describe the recent advances and pitfalls of nitrite-based therapy, with special attention to its application in cardiovascular disorders, inflammation, and anti-bacterial defence. It can be concluded that nitrite (as well as nitrate-rich diet for long-term applications) may hold promise as therapeutic agent in vascular dysfunction and ischemic injury, as well as an effective compound able to promote angiogenesis.

Oxygenation and plasma endothelin-1 concentrations in healthy horses recovering from isoflurane anaesthesia administered with or without pulse-delivered inhaled nitric oxide

OBJECTIVE

To assess oxygenation, ventilation-perfusion (V/Q) matching and plasma endothelin (ET-1) concentrations in healthy horses recovering from isoflurane anaesthesia administered with or without pulse-delivered inhaled nitric oxide (iNO).

STUDY DESIGN

Prospective experimental trial.

ANIMALS

Healthy adult Standardbred horses.

METHODS

Horses were anaesthetized with isoflurane in oxygen and placed in lateral recumbency. Six control (C group) horses were anaesthetized without iNO delivery and six horses received pulse-delivered iNO (NO group). After 2.5 hours of anaesthesia isoflurane and iNO were abruptly discontinued, inhaled oxygen was reduced from 100% to approximately 30%, and the horses were moved to the recovery stall. At intervals during a 30-minute period following the discontinuation of anaesthesia, arterial and mixed venous blood gas values, shunt fraction (Qs/Qt), plasma ET-1 concentration, pulse rate and respiratory rate were measured or calculated. Repeated measures anova and a Bonferroni post hoc test was used to analyze data with significance set at p < 0.05.

RESULTS

At all time points in the recovery period, NO horses maintained better arterial oxygenation (oxygen partial pressure: NO 13.2 ± 2.7-11.1 ± 2.7 versus C 6.7 ± 1.1-7.1 ± 1.1 kPa) and better V/Q matching (Qs/Qt NO 0.23 ± 0.05-0.14 ± 0.06 versus C 0.48 ± 0.03-0.32 ± 0.08%) than C horses. Mixed venous oxygenation was higher in NO for 25 minutes following the discontinuation of anaesthesia (NO 6.3 ± 0.2-4.5 ± 0.07 versus C 4.7 ± 0.6-3.7 ± 0.3 kPa). In both groups of horses arterial oxygenation remained fairly stable; venous oxygenation declined over this time period in the NO group but still remained higher than venous oxygen in the C group. ET-1 concentrations were higher at most time points in C than NO. Changes in other parameters were either minor or absent.

CONCLUSIONS AND CLINICAL RELEVANCE

Delivery of iNO to healthy horses during anaesthesia results in better arterial and venous oxygenation and V/Q matching (as determined by lower Qs/Qt) and lower ET-1 concentrations throughout a 30-minute anaesthetic recovery period.

Transpulmonary flux of S-nitrosothiols and pulmonary vasodilation during nitric oxide inhalation: role of transport

Inhaled nitric oxide (iNO) is used to treat pulmonary hypertension and is being investigated for prevention of bronchopulmonary dysplasia in neonates. Extrapulmonary effects of iNO are widely recognized, but the underlying chemistry and pharmacology are poorly understood. Growing evidence suggests that, in addition to acting via diffusion, NO can be converted into nitrosants capable of reacting with endogenous L-cysteine (L-Cys) in the alveolar lining fluid, forming S-nitrosothiol (SNO)-L-cysteine (CSNO). CSNO can then enter cells via the type L amino acid transporter (LAT). To determine the influence of LAT and supplemental L-Cys on the functional activity of iNO and transpulmonary movement of SNOs or other related species, we exposed C57Bl6 mice to nebulized L-Cys or D-cysteine (D-Cys) and/or LAT competitors. Isolated lungs were then perfused with physiologic buffer while effluent was collected to assay perfusate SNOs. Nebulized L-Cys, but not D-Cys, augmented the iNO-induced increase in circulating SNOs in the effluent without altering iNO-induced pulmonary vasodilation. Addition to the perfusate of either L-leucine (L-Leu) or 2-amino-2-norborane carboxylic acid, two distinct LAT competitors, inhibited appearance in the perfusate of SNOs in L-Cys-exposed lungs; a higher concentration of L-Leu significantly inhibited the iNO-induced pulmonary vasodilation as well as SNO accumulation. We conclude that iNO-induced pulmonary vasodilation and the transpulmonary movement of iNO-derived SNOs are mediated in part by formation of extracellular CSNO, uptake by alveolar epithelial LAT, and/or export by LAT from the pulmonary endothelium into the circulation. Therapies that exploit and optimize LAT-dependent SNO transport might improve the efficacy of and clinical outcomes with NO-based therapy by improving systemic SNO delivery.

Critical care of the end-stage liver disease patient awaiting liver transplantation

Patients with end-stage liver disease awaiting liver transplantation frequently require intensive care admission and management due to either complications of liver failure or to intercurrent illness, particularly infection. Mortality in such patients is high and the development of an illness necessitating intensive care unit management can influence transplant candidacy. Specialized support frequently requires hemodynamic support, mechanical ventilation, and renal support. In this review, areas of management of particular importance to patients with end-stage liver disease in the intensive care unit are discussed. These areas are hepatic encephalopathy, infectious diseases, cardiovascular support, mechanical ventilation, renal support and combined transplantation, and decisions regarding delisting. Current knowledge specific to these patients, when available, is discussed, current practice is described, and areas of uncertainty in the evidence are discussed.