Inhaled nitric oxide does not improve cardiac or pulmonary function in patients with an exacerbation of chronic obstructive pulmonary disease

Inhaled pulmonary vasodilators: a narrative review

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

Update on pulmonary hypertension complicating chronic obstructive pulmonary disease

Pulmonary hypertension (PH) is the hemodynamic manifestation of various pathological processes that result in elevated pulmonary artery pressures (PAP). The National Institutes of Health Registry defined pulmonary arterial hypertension as the mean PAP of more than 25 mm Hg with a pulmonary capillary wedge pressure or left atrial pressure equal to or less than 15 mm Hg. This definition remains the currently accepted definition of PH that is used to define PH related to multiple clinical conditions including chronic obstructive pulmonary disease (COPD). The estimated US prevalence of COPD by the National Health Survey in 2002 in people aged >25 was 12.1 million. There is a lack of large population-based studies in COPD to document the correct prevalence of PH and outcome. The major cause of PH in COPD is hypoxemia leading to vascular remodeling. Echocardiogram is the initial screening tool of choice for PH. This simple noninvasive test can provide an estimate of right ventricular systolic and right atrial pressures. Right heart catheterization remains the gold standard to diagnose PH. It provides accurate measurement of mean PAP and pulmonary capillary wedge pressure. Oxygen therapy remains the cornerstone therapeutic for hypoxemia in COPD patients. Anecdotal reports suggest utility of PDE5-inhibitors and prostacyclin to treat COPD-related PH. Large randomized clinical trials are needed before the use of these drugs can be recommended.

Clinical indication for use and outcomes after inhaled nitric oxide therapy

BACKGROUND

Inhaled nitric oxide (iNO) use is widespread, but the long-term outcomes after therapy in adult patients remain unknown.

METHODS

All 376 patients receiving perioperative iNO (excluding pediatric and interventional cardiology procedures) at Columbia University Medical Center were prospectively followed from 2000 to 2003. Survival data were collected from chart review.

RESULTS

Inhaled nitric oxide was used to treat pulmonary and right ventricular failure in patients undergoing orthotopic heart transplantation (OHT, n = 67), orthotopic lung transplantation (n = 45), cardiac surgery (n = 105), and ventricular assist device placement (n = 66), and for hypoxemia in other surgery (n = 34) and medical patients (n = 59). Average follow-up was 2.9 +/- 1.0 years. Overall mortality was lowest when iNO was used after OHT (25.4%) and orthotopic lung transplantation (37.8%), intermediately after cardiac surgery (61%), ventricular assist device (62%), and other surgery patients (75%), and highest among medical patients (90%; all p < 0.005). The cost of iNO therapy was lower in transplantation versus medical patients, with a trend toward shorter duration of use. In multivariate analysis, respiratory failure and use in non-OHT were independent predictors of mortality (both p = 0.001). A risk score greater than 1 (score = non-OHT use 1, plus right ventricular failure 1) predicted a mortality of 76.5% versus 37.2% (p < 0.001).

CONCLUSIONS

Use of iNO for pulmonary hypertension in patients undergoing OHT and orthotopic lung transplantation was associated with a significantly lower overall mortality rate compared with its use after cardiac surgery or for hypoxemia in medical patients. Inhaled nitric oxide does not appear to be cost effective when treating hypoxemia in medical patients with high-risk scores and irreversible disease.

Inhaled nitric oxide therapy in adults: European expert recommendations

BACKGROUND

Inhaled nitric oxide (iNO) has been used for treatment of acute respiratory failure and pulmonary hypertension since 1991 in adult patients in the perioperative setting and in critical care.

METHODS

This contribution assesses evidence for the use of iNO in this population as presented to a expert group jointly organised by the European Society of Intensive Care Medicine and the European Association of Cardiothoracic Anaesthesiologists.

CONCLUSIONS

Expert recommendations on the use of iNO in adults were agreed on following presentation of the evidence at the expert meeting held in June 2004.

Comparative effects of inhaled budesonide and the NO-donating budesonide derivative, NCX 1020, against leukocyte influx and airway hyperreactivity following lipopolysaccharide challenge

Lipopolysaccharide (LPS) inhalation (30 microg ml(-1), 1 h) caused airway hypereactivity (AHR) to histamine (1 mM, 20 s) 1 h later in conscious guinea-pigs. Bronchoalveolar lavage fluid (BALF) levels of neutrophils, myeloperoxidase (MPO) and protein were elevated whereas nitric oxide (NO) metabolites were reduced 1 h after LPS compared with saline challenge. 24 h after LPS, there was no AHR, but BALF neutrophils, eosinophils, macrophages, MPO, protein and NO metabolites were all raised. Budesonide (0.7 mM) and a molar equivalent concentration of the NO-donating budesonide derivative, NCX 1020, were inhaled (15 min) at 24 h and 45 min before LPS. The only change produced by budesonide was to reduce eosinophil influx at 24 h after LPS, compared with vehicle treated animals. NCX 1020, however, blocked AHR and reduced neutrophils (1 and 24 h) and MPO (1 and 24 h), while NO levels were raised at 1 and reduced at 24 h after LPS. The combined inhalation before LPS of the NO donor, SNAP (1.4 mM), with budesonide (0.7 mM) blocked the AHR to histamine and significantly reduced neutrophils (1 and 24 h) and MPO (1 and 24 h), while NO levels were raised at 1 h after LPS. Thus, NO and a corticosteroid co-administered as NCX 1020 or budesonide with a NO donor, have an additive effect against LPS-induced inflammatory responses and may have value in the treatment of neutrophil-driven airways disease such as COPD.

Intratracheal adenoviral-mediated delivery of iNOS decreases pulmonary vasoconstrictor responses in rats

We hypothesized that adenovirus-mediated inducible nitric oxide synthase (iNOS) gene transduction of the lung would result in time-dependent iNOS overexpression and attenuate the vascular constrictor responses to a thromboxane mimetic, U-46619. Rats were treated via the trachea with surfactant alone (sham), surfactant containing an adenoviral construct with a cytomegalovirus promoter-regulated human iNOS gene (Adeno-iNOS), or an adenoviral construct without a gene insert (Adeno-Control). Adeno-iNOS-transduced rats demonstrated human iNOS mRNA and increased iNOS protein levels only in the lungs. Immunohistochemistry of lungs from Adeno-iNOS-treated animals demonstrated transgene expression in alveolar wall cells. In the lungs from Adeno-iNOS-transduced rats, the expression of iNOS protein and exhaled nitric oxide concentrations were increased on days 1-4 and 7 but returned to baseline values by day 14. The administration of the selective iNOS inhibitor L-N6-(1-iminoethyl)lysine dihydrochloride (L-NIL) decreased exhaled nitric oxide concentrations to levels found in Adeno-Control-transduced lungs. In a second group of rats, the segmental vasoconstrictor responses to U-46619 were determined in isolated, perfused lungs 3 days after transduction. Lungs from rats transduced with Adeno-iNOS had reduced total, arterial, and venous vasoconstrictor responses to U-46619 compared with sham, Adeno-Control, and control groups. In a third set of experiments, the response to 400 nM U-46619 in the presence of 10 microM L-NIL was not different in the isolated lungs from Adeno-Control- and Adeno-iNOS-transduced rats. We conclude that adenovirus-mediated iNOS gene transduction of the lung results in time-dependent iNOS overexpression, which attenuates the vascular constrictor responses to the thromboxane mimetic U-46619.

The role of oxidative stress in chronic obstructive pulmonary disease

Tobacco smoke is the number one risk factor for chronic obstructive pulmonary disease (COPD) and contains a high concentration of oxidants. The lung has a high concentration of antioxidants and antioxidant enzymes; however, COPD patients show evidence of increased oxidative stress suggesting that endogenous antioxidants may be insufficient to prevent oxidative damage from cigarette smoke. The consequences of increased oxidative stress in the lung include increased transcription of inflammatory genes, increased protease activity, and increased mucus secretion. Oxidative stress is often associated with impaired skeletal muscle function and may be one of the causes of glucocorticoid resistance. While current pharmacologic approaches to the treatment of chronic obstructive pulmonary disease do not commonly include antioxidants, preclinical studies involving animal models suggest that antioxidant superoxide dismutase mimetics offer a potential new therapeutic approach to the prevention and treatment of chronic obstructive pulmonary disease.

Nitric oxide in respiratory diseases

The formation and modulation of nitric oxide (NO) in the lungs is reviewed. Its beneficial and deleterious roles in airways diseases, including asthma, chronic obstructive pulmonary disease, and cystic fibrosis, and in animal models is discussed. The pharmacological effects of agents that modulate NO production or act as NO donors are described. The clinical pharmacology of these agents is described and the therapeutic potential for their use in airways disease is considered.

Severe pulmonary hypertension in a patient with bronchiectasis complicated by cor pulmonale and a right-to-left shunt presenting for surgery

A patient with advanced bronchiectasis, severe pulmonary hypertension complicated by cor pulmonale and a right-to-left shunt at atrial level presented for sigmoid colectomy. We outline the potential perioperative problems of this situation, discuss the perioperative risks and describe our clinical approach. A total intravenous anaesthetic technique using midazolam, fentanyl, ketamine and rocuronium was used to minimize changes in pulmonary and systemic vascular resistance and not induce bronchospasm. Preoperative nebulized salbutamol and ipratroprium were given to prevent bronchospasm and adrenaline and noradrenaline were infused to maintain cardiac output and the balance between systemic and pulmonary vascular resistance.

Inhaled nitric oxide: more than a selective pulmonary vasodilator

Because of its high diffusing capacity through the alveolar-blood barrier and its high selectivity for the pulmonary vasculature, inhaled nitric oxide (NO) has been recently shown to be a viable and efficient approach to restore pulmonary NO deficiency. The most relevant applications of inhaled NO are in infants with primary pulmonary hypertension or hypoxia. In these patients, inhaled NO improves gas exchange and ventilation-perfusion matching, reduces the length of hospitalization and is without severe detrimental effects. The use of inhaled NO has also been extended to adults with pulmonary hypertension and the acute respiratory distress syndrome. In addition, recent clinical evidence supported by data from animal models, shows beneficial extra-pulmonary effects of inhaled NO, including protection against myocardial ischaemia-reperfusion injury.

Inhaled diazeniumdiolates (NONOates) as selective pulmonary vasodilators

Selective pulmonary vasodilators cause vasodilatation limited to the pulmonary vasculature, within well-ventilated lung regions. Selective pulmonary vasodilators ideally cause only a minimal effect on the systemic circulation and improve ventilation/perfusion matching. NONOates are a novel group of chemical compounds that spontaneously and continuously release nitric oxide under physiological conditions, over periods of up to 24 h. Inhaled NONOates retain the benefits of gaseous nitric oxide without many of its therapeutic disadvantages. This review focuses on the therapeutic potential of inhaled NONOates in pulmonary hypertension, other lung conditions associated with right ventricular dysfunction and in asthma. The potential toxicity of NONOates is also discussed.

Combined inhalation of nitric oxide and oxygen in patients with moderate to severe COPD: effect on blood gases

Inhaled nitric oxide (NO) has been reported to improve oxygenation in patients with COPD if administered in combination with oxygen (O2). Little, however, is known about the variability of these effects and the potential influence of body position. Twenty-six spontaneously breathing patients with moderate to severe COPD inhaled clean air, O2(FiO2, 0.29), 5 ppm NO, 5 ppm NO+O2, 10 ppm NO+O2, 10 ppm NO, and again clean air in an upright position. Blood gas analysis from arterialized capillary blood was performed after each inhalation. Tests were repeated on different days to assess the variability of the response. Furthermore, eight patients were studied in both upright and supine position while inhaling 5 ppm NO in the presence or absence supplemental O2. As compared to clean air, NO led to a mean decrease in PaO2 of -0.9 mmHg at 5 ppm and of -2.8 mmHg at 10 ppm NO. Similarly, NO+O2 led to a dose-dependent fall in PaO2 of -1.8 and -3.6 mmHg, respectively, as compared to O2. Average within-subject variation (SD) of the effects elicited by 5 and 10 ppm NO was 2.4 and 2.3 mmHg without additional O2, and 4.7and 5.3 mmHg with O2. The effects of 5 ppm NO+O2 differed significantly between upright and supine position; as compared to O2 alone, mean (SD) changes were -3.7 +/- 5-8 vs. +1.1 +/- 4.9 mmHg, respectively. Our findings suggest thatthe addition of NO to inhaled oxygen, when given in an upright position, does not lead to an improvement of PaO2 in patients with moderate to severe COPD. Furthermore, it turned out that it was not possible to define responders and non-responders to inhaled NO on an individual basis, since the variability ofthe responses was similar to the mean