Combined nitric oxide inhalation, prone positioning and almitrine infusion improve oxygenation in severe ARDS

S2e guideline: positioning and early mobilisation in prophylaxis or therapy of pulmonary disorders : Revision 2015: S2e guideline of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI)

The German Society of Anesthesiology and Intensive Care Medicine (DGAI) commissioneda revision of the S2 guidelines on "positioning therapy for prophylaxis or therapy of pulmonary function disorders" from 2008. Because of the increasing clinical and scientificrelevance the guidelines were extended to include the issue of "early mobilization"and the following main topics are therefore included: use of positioning therapy and earlymobilization for prophylaxis and therapy of pulmonary function disorders, undesired effects and complications of positioning therapy and early mobilization as well as practical aspects of the use of positioning therapy and early mobilization. These guidelines are the result of a systematic literature search and the subsequent critical evaluation of the evidence with scientific methods. The methodological approach for the process of development of the guidelines followed the requirements of evidence-based medicine, as defined as the standard by the Association of the Scientific Medical Societies in Germany. Recently published articles after 2005 were examined with respect to positioning therapy and the recently accepted aspect of early mobilization incorporates all literature published up to June 2014.

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.

Surfactant therapy for acute lung injury and acute respiratory distress syndrome

This article examines exogenous lung surfactant replacement therapy and its usefulness in mitigating clinical acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). Surfactant therapy is beneficial in term infants with pneumonia and meconium aspiration lung injury, and in children up to age 21 years with direct pulmonary forms of ALI/ARDS. However, extension of exogenous surfactant therapy to adults with respiratory failure and clinical ALI/ARDS remains a challenge. This article reviews clinical studies of surfactant therapy in pediatric and adult patients with ALI/ARDS, focusing on its potential advantages in patients with direct pulmonary forms of these syndromes.

[The prone position in acute respiratory distress syndrome: a critical systematic review]

OBJECTIVE

To do a critical systematic review regarding effects of prone positioning (PP) in patients with acute respiratory distress syndrome (ARDS).

METHODS

A systematic review (Highwire, Medline, Cochrane Library from 1976 to 2004), using the keywords: prone position, acute respiratory distress syndrome, allowed us to include the human studies on PP in ARDS patients, independantly of their objectives or their type of protocol. To appreciate the studies validity, we scored the quality evidence of the studies in order to grade our conclusions.

RESULTS AND CONCLUSION

The qualitative analysis of the 58 included studies (1,500 patients returned prone, 4,000 episodes of PP) led to the following main conclusions: 1) the PP improves oxygenation in the majority of ARDS patients (level of evidence I); 2) the PP improves the pulmonary haemodynamics without altering the systemic haemodynamics (level of evidence III); 3) the PP enhances the recruitment maneuvers (level of evidence III); 4) because there are no formal predictive criteria for response to the PP, a "trial of PP" or better two PP trials are necessary to look for the responders; 5) the PP should be performed as early as possible in the course of severe ARDS; 6) the optimal duration of PP is 18 to 23 hours daily, and it should be continued until improvement of arterial oxygenation, or loss of the positive effect of PP on arterial oxygenation or evidently patient's death.

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.

Acute Respiratory Distress Syndrome

Acute lung injury is a syndrome diagnosed clinically and is one of the most common causes of respiratory failure seen in the intensive care unit. A consensus definition of this and its more severe form, acute respiratory distress syndrome (ARDS), has allowed for better consistency in determining the epidemiology and facilitates consistent clinical trial design to better find therapies to treat or prevent it. Patients who present with ARDS usually show signs of tachpnea or dyspnea and have underlying conditions that promote inflammatory responses. The pathogenesis involves an inflammatory insult that eventually destroys the pulmonary capillary vasculature as well as alveoli. Pathophysiologically, the patient with ARDS may progress through as many as 3 phases: exudative, proliferative, and fibrotic. Treatment options can be either nonpharmacologic or pharmacologic and are limited. Ventilator strategies such as low-tidal-volume ventilation have improved outcomes in these patients, while corticosteroid use is not as established to provide morbidity or mortality benefit. Other therapies have been investigated with inconclusive or disappointing results for the treatment of this fatal syndrome.

Acute respiratory distress syndrome

Several combination therapies have been described throughout this article: in all likelihood, it is combination therapy that will allow improved survival of ARDS patients. As medicine moves into the future, clinical trials evaluating the efficacy of therapies for ARDS will be performed. In human critical care medicine, a large forward step was taken when ALI and ARDS were clearly defined. Unfortunately. as good as the definition is, ALI and ARDS occur secondary to many different underlying pathologic processes,perhaps obscuring the benefits of certain therapies for ARDS based on the underlying condition, for example, trauma versus sepsis. Selection of patients entering any ARDS trial is crucial: not only must those patients meet the strict definition of ARDS but the underlying disease process should be clearly identified. Identification of patients suffering from different disease processes before the onset of ARDS will allow for stratification of outcomes according to the intervention and the underlying pathology--comparing apples to apples and not to oranges. We are in a unique position in veterinary medicine. Although frequently financially limited by our clients, we have the opportunity to achieve several goals. First, we need to clearly define what constitutes ALI and ARDS in veterinary medicine. Do we want to rely on the human definitions? Probably not; however, as a group, we need to determine what we will accept as definitions. For example, we may not be able perform right heart catheterizations on all our patients to meet the wedge pressure requirement of human beings of less than 18 mm Hg. Do we agree that a PAOP of less than 18 mmHg is appropriate for animals, and is it appropriate for all animals? Will we accept another measure, for example, pulmonary artery diameter increases with echocardiographic evidence of acceptable left heart function? What is acceptable left heart function? As veterinarians, what do we consider to be hypoxemia? Is it the same in all species that we work with? What do we define as acute onset? Most human ARDS cases occur while patients are in hospital being treated for other problems, whereas many of our patients present already in respiratory distress. If we are unable to ventilate patients for economic or practical reasons, what do we use as the equivalent of the Pao2/Flo, ratio'? Reliance on the pathologist is not reasonable, because many disease processes can look similar to ARDS under the microscope. If anything, ALI and ARDS are clinical diagnoses. It is time for veterinarians to reach a consensus on the definition for ALI and ARDS in our patients. Only when we have a consensus of definition can rational prospective clinical trials of therapies be designed.

Inhaled nitric oxide for acute hypoxic respiratory failure in children and adults: a meta-analysis

We systematically reviewed randomized controlled trials examining inhaled nitric oxide (INO) for the treatment of acute respiratory distress syndrome or acute lung injury in children and adults. Qualitative assessments of identified trials were made, and metaanalyses were performed according to Cochrane methodology. Five randomized controlled trials (n = 535) met entry criteria. One study demonstrated significant improvement in oxygenation in the first 4 days of treatment, with no difference after this. There was no difference in ventilator-free days between treatment and placebo groups, and no specific dose of INO was more advantageous than any other. INO had no effect on mortality in trials without crossover of treatment failures to open-label INO (relative risk, 0.98; 95% confidence interval, 0.66-1.44). Other clinical indicators of effectiveness, such as duration of hospital and intensive care stay, were inconsistently reported. Lack of data prevented assessment of all outcomes. If further trials assessing INO in acute respiratory distress syndrome or acute lung injury are to proceed, they should be stratified for primary etiology, incorporate other modalities that may affect outcome, and evaluate clinically relevant outcomes before any benefit of INO can be excluded.

[Effects of prone position, inhaled nitric oxide and surfactant in children with hypoxemic pulmonary disease]

OBJECTIVE

To analyze the therapeutic response to prone position, inhaled nitric oxide (NO) and surfactant in children with hypoxemic pulmonary disease.

PATIENTS AND METHODS

We studied the effect of prone position, NO, and surfactant in critically ill children with acute hypoxemic pulmonary disease unresponsive to conventional therapy. We analyzed PaO2, SatO2, the PaO2/FiO2 ratio, oxygenation index and PaCO2 before and after each treatment, as well as the subsequent clinical course. An increase of more than 20 % in the PaO2/FiO2 ratio was considered a positive response.

RESULTS

Ninety treatments were administered in 56 patients: 55 patients were treated with NO, 18 with prone position and 17 with surfactant. All three treatments substantially improved oxygenation. The mean increase in the PaO2/FiO2 ratio was 35 % with nitric oxide, 33 % with prone position and 50 % with surfactant. The mean decrease in oxygenation index was 22 % with nitric oxide, 24 % with prone position and 17 % with surfactant. Seventy-one percent of patients treated with NO, 61 % of patients treated with prone position, and 64 % of patients who received surfactant were responders. The three treatments produced a slight decrease in PaCO2 (2.5 mmHg with nitric oxide, 4.7 mmHg with prone position and 5.1 mmHg with surfactant).

CONCLUSIONS

Inhaled NO, prone position and surfactant improve oxygenation in some children with hypoxic pulmonary disease.

Inhaled nitric oxide for acute hypoxemic respiratory failure in children and adults

BACKGROUND

Acute hypoxemic respiratory failure affects all age groups and may result from a number of systemic diseases. It continues to be associated with high mortality and morbidity. Initial studies examining the effect of inhaled nitric oxide in respiratory failure demonstrated transient improvement in oxygenation but did not examine mortality or other significant morbidity outcomes.

OBJECTIVES

To systematically examine randomized controlled trials addressing the effect of inhaled nitric oxide, compared with placebo inhaled gas, on mortality and morbidity in patients with acute hypoxemic respiratory failure.

SEARCH STRATEGY

Randomized controlled trials were identified from electronic databases: The Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2, 2002;MEDLINE (January 1966-August 2002); EMBASE (1980-March 2001); CINAHL (1982-July 2002), as well as from bibliographies of retrieved articles. Relevant journals and conference proceedings were hand searched and authors published in this field were contacted for knowledge of unpublished ongoing trials.

SELECTION CRITERIA

Randomized controlled trials comparing inhaled nitric oxide with maximal conventional therapy and inhaled placebo, in either children or adults with acute hypoxemic respiratory failure.

DATA COLLECTION AND ANALYSIS

Qualitative assessment of each trial was made and analyses performed according to statistical methods in Review Manager MetaView 4.1. A sub-group analysis was performed to assess the impact of inhaled nitric oxide at varied doses.

MAIN RESULTS

Five randomized controlled trials were evaluated, assessing 535 patients with acute hypoxemic respiratory failure (Age range not provided). Lack of data prevented assessment of all outcomes. There was no significant difference of nitric oxide on mortality in trials without cross-over (RR 0.98, 95%CI 0.66,1.44). Published evidence from one study demonstrated nitric oxide to transiently improve oxygenation in the first 72 hours of treatment. Limited data demonstrated no significant difference in ventilator-free days between treatment and placebo groups, and no specific dose of nitric oxide was significantly advantageous over another. Other clinical indicators of effectiveness, such as duration of hospital and intensive care stay, were inconsistently reported. There were no significant complications directly attributable to this treatment.

REVIEWER'S CONCLUSIONS

Nitric oxide did not demonstrate any statistically significant effect on mortality and transiently improved oxygenation in patients with hypoxemic respiratory failure. Lack of data prevented assessment of other clinically relevant end points. If further trials comparing inhaled nitric oxide with an inhaled placebo are to proceed, they should be stratified for primary disease, assess the impact of other combined treatment modalities for respiratory failure, and must specifically evaluate clinically relevant outcomes, before any benefit of inhaled nitric oxide for respiratory failure can be excluded.

Inhaled nitric oxide in ARDS

The role of nitric oxide (NO) in numerous physiologic systems only recently has been discovered. When used as a gas, inhaled NO (iNO) has many unique properties that cause immediate improvements in pulmonary hemodynamics and oxygenation. Acute benefits in physiologic parameters have been demonstrated in numerous studies of iNO in acute respiratory distress syndrome (ARDS), but recent randomized controlled trials have failed to show improvement in outcome. The addition of other treatments that prolong or enhance the affect of iNO or its use with other ventilator modalities such as prone positioning or high-frequency ventilation offer hope that iNO may be beneficial in select groups of patients.

Short-term effects of inhaled nitric oxide and prone position in pulmonary and extrapulmonary acute respiratory distress syndrome

Inhaled nitric oxide (NO) and prone position (PP) are frequently used in the treatment of acute respiratory distress syndrome (ARDS). We compared the gas exchange and hemodynamic effects induced by the combination of NO inhalation and PP in patients with ARDS and analyzed whether or not pulmonary (Pu) and extrapulmonary (Epu) ARDS patients behave differently. Eight Pu and seven Epu ARDS patients were studied in four situations: supine position (SP); SP with NO inhalation at 5 ppm (SP + NO); PP; and PP with NO inhalation (PP + NO). In comparison with SP, NO inhalation and PP induced significant increases in Pa(O(2))/FI(O(2)) (from 106 +/- 58 in SP to 131 +/- 69 mm Hg in SP + NO, p = 0.01, and to 184 +/- 67 mm Hg in PP, p < 0.001). Pu and Epu ARDS showed a similar improvement in Pa(O(2))/FI(O2) with PP. Only Pu ARDS patients showed a significant increase (p < 0.001) in oxygenation induced by NO inhalation from 81 +/- 45 to 100 +/- 50 mm Hg in SP, and from 146 +/- 53 to 197 +/- 98 mm Hg in PP. In conclusion, PP is associated with a marked improvement in oxygenation, irrespective of the causes of ARDS, and additive effects of NO inhalation are mainly seen in patients with Pu ARDS.

Inhaled nitric oxide administration during one-lung ventilation in patients undergoing thoracic surgery

OBJECTIVE

To evaluate the effects of inhaled nitric oxide (iNO) on hemodynamics and oxygenation during one-lung ventilation (OLV) in the lateral decubitus position in patients undergoing elective thoracic surgery.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Thirty consecutive patients scheduled for thoracotomy.

INTERVENTIONS

Anesthesia consisted of thoracic epidural analgesia combined with general anesthesia (isoflurane, fentanyl, and vecuronium bromide). Systemic and pulmonary circulations were monitored with a radial artery catheter and a pulmonary artery catheter. Inhaled NO, 40 ppm, was administered during OLV, and the inhaled gas mixture was monitored for NO and nitrogen dioxide (NO2). Hemodynamic and oxygenation data were collected before and during inhaled NO administration.

MEASUREMENTS AND MAIN RESULTS

Inhaled NO caused a reduction of pulmonary vascular resistance index from 249 +/- 97.6 dyne. sec. cm(-5) to 199.3 +/- 68.9 dyne. sec. cm(-5) (p < 0.05), without effects on systemic hemodynamics or impairment of oxygenation. A stratification of the patients according to values of QS/QT (< 30%, 30% to 44%, > or = 45%), PaO(2)/fraction of inspired oxygen (> or = 200, 100 to 199, < 100), and pulmonary hypertension (mean pulmonary arterial pressure < 24 or > or = 24 mmHg) showed that inhaled NO causes a significant reduction of mean pulmonary artery pressure in patients with pulmonary hypertension, mainly as a result of a reduction of pulmonary vascular resistance index, and improves oxygenation by reducing intrapulmonary shunt in patients with severe hypoxemia during OLV.

CONCLUSIONS

Inhaled NO administration neither significantly decreased mean pulmonary arterial pressure in patients with normal pulmonary artery pressure nor improved oxygenation in nonhypoxic patients. Nevertheless, inhaled NO is effective in patients with pulmonary hypertension and hypoxemia during OLV.

Comparison of prone positioning and continuous rotation of patients with adult respiratory distress syndrome: results of a pilot study

OBJECTIVE

To compare prone positioning and continuous rotational therapy with respect to oxygenation and hemodynamics in patients suffering from adult respiratory distress syndrome (ARDS).

DESIGN

Randomized, prospective pilot study.

SETTING

Intensive care unit at a university hospital.

PATIENTS

Twenty-six mechanically ventilated patients with ARDS from nontraumatic causes.

INTERVENTIONS

Twelve patients were turned prone (group 1), 14 patients underwent continuous axial rotation from one lateral position to the other with a maximum angle of 124 degrees in specially designed beds (group 2). All patients had received inhaled nitric oxide (NO) therapy before positioning.

MEASUREMENTS AND MAIN RESULTS

Gas exchange and hemodynamics were assessed using a pulmonary artery catheter. In both groups, an improvement in PaO2/RFIO2-ratio and intrapulmonary shunt fraction occurred after initiation of NO as well as during the first 72 hrs of positioning therapy. During the study period, seven patients died in group 1 and nine patients in group 2 (p = NS). Comparing the areas under the curve during the first 72 hrs, no significant differences with respect to PaO2/FIO2-ratio, PaCO2, positive end-expiratory and peak inspiratory pressure levels, intrapulmonary shunt fraction, the alveolar-arterial oxygen difference, and oxygen delivery and consumption, as well as cardiac index, pulmonary and arterial blood pressures, and pulmonary arterial occlusion pressure could be detected between the groups. Prone positioning was tolerated well, continuous rotational therapy had to be modified according to hemodynamic instability in three patients.

CONCLUSIONS

In severe lung injury, continuous rotational therapy seems to exert effects comparable to prone positioning and could serve as alternative when prone positioning seems inadvisable.

Thirty years of clinical trials in acute respiratory distress syndrome

OBJECTIVE

To systematically review clinical trials in acute respiratory distress syndrome (ARDS).

DATA SOURCES

Computerized bibliographic search of published research and citation review of relevant articles.

STUDY SELECTION

All clinical trials of therapies for ARDS were reviewed. Therapies that have been compared in prospective, randomized trials were the focus of this analysis.

DATA EXTRACTION

Data on population, interventions, and outcomes were obtained by review. Studies were graded for quality of scientific evidence.

MAIN RESULTS

Lung protective ventilator strategy is supported by improved outcome in a single large, prospective trial and a second smaller trial. Other therapies for ARDS, including noninvasive positive pressure ventilation, inverse ratio ventilation, fluid restriction, inhaled nitric oxide, almitrine, prostacyclin, liquid ventilation, surfactant, and immune-modulating therapies, cannot be recommended at this time. Results of small trials using corticosteroids in late ARDS support the need for confirmatory large clinical trials.

CONCLUSIONS

Lung protective ventilator strategy is the first therapy found to improve outcome in ARDS. Trials of prone ventilation and fluid restriction in ARDS and corticosteroids in late ARDS support the need for large, prospective, randomized trials.

Hemodynamic and gas exchange response to inhaled nitric oxide and prone positioning in acute respiratory distress syndrome patients

OBJECTIVE

To analyze the single effect and the interaction of prone position and inhaled nitric oxide (iNO) on lung function and hemodynamic variables.

DESIGN

2 x 2 factorial trial.

SETTING

Department of intensive care medicine at a university hospital.

PATIENTS

Fourteen patients on volume-controlled mechanical ventilation for acute respiratory distress syndrome (ARDS).

INTERVENTION

Four experimental conditions, each one characterized by the patient's position (supine or prone) with iNO or without iNO.

MEASUREMENTS AND RESULTS

Hemodynamic and gas exchange data were collected for each experimental condition. PaO2 was increased both by positioning (p < .01) and iNO (p < .01); iNO caused also a reduction in venous admixture (p < .01), pulmonary artery pressure (p < .01), and pulmonary vascular resistance index (p < .05). We could not demonstrate any significant interaction between the two treatments. The average effect of prone positioning was the same both with and without iNO, whereas the average effect of iNO was the same in both the prone and the supine position.

CONCLUSION

In the studied acute respiratory distress syndrome patients the average effects of iNO and positioning on oxygenation were additive and no interaction could be shown. A strategy including both treatments could warrant the best improvement in oxygenation, and should take into account the individual response to each treatment and the possible combination of the two.

[Effect of bronchial drainage on the improvement in gas exchange observed in ventral decubitus in ARDS]

OBJECTIVES

A bronchial secretion draining effect is frequently suggested as a mechanism for oxygenation improvement during prone positioning (PP) in patients with acute respiratory distress syndrome (ARDS). Nevertheless, it has never really been evaluated. The aim of this study was to search for an interrelationship between the volume of the bronchial secretion and the improvement of the PaO2/FIO2 ratio during prone positioning, with NO inhalation or not.

STUDY DESIGN

Open prospective clinical study.

PATIENTS

The study included 15 consecutive patients with severe ARDS (PaO2/FIO2 < 200 after alveolar recruitment, Murray score > 2.5).

METHODS

They were returned to the prone position for 4 hours (h0-h4) combined with an inhalation of 5 ppm NO during 1 hour (h2-h3). Tracheal suction were performed hourly between h-2 and h6 and weighed on a precision scale from h-1 to h6. Haemodynamic, blood gas and respiratory compliance were recorded at h0, h2, h3, h4 and h6.

RESULTS

No significant haemodynamic changes were observed in the various phases. Compared with the baseline condition at h0, PP and PP + NO respectively improved PaO2/FIO2 by 102 +/- 62% at h2 (P < 0.005) and 156 +/- 79% at h3 (P < 0.005/h0 and < 0.01/h2). 14/15 patients responded to PP and 15/15 to PP + NO (gain in PaO2/FIO2 > 10%). Concerning secretions, we collected 3.0 +/- 7.5 g, 4.4 +/- 6.1 g, 1.7 +/- 1.4 g and 1.7 +/- 1.6 between h-2 and h0, h0 and h2, h2 and h4, h4 and h6. Individual assessments showed no relationship between the PaO2/FIO2 evolution at any time and the quantity of secretions obtained during the first 2 hours in the prone position. Six patients presented secretions of less than 1 g between h0 and h2, and for whom the improvement in oxygenation was higher than average (115 +/- 53% at h2).

CONCLUSION

In patients with little or moderate secretions, the improvement observed in oxygenation, with or without NO, does not depend on their volume.

Nitric oxide inhalation in pulmonary hypertension and severe respiratory failure

Inhalation of nitric oxide (NO) can cause selective pulmonary vasodilation in aerated lung regions; thus, it may be of benefit in the treatment of various forms of pulmonary hypertension and respiratory distress due to a mismatch of pulmonary ventilation and perfusion. The specific characteristics of inhaled NO exclude long-term treatment, but NO has been successfully used as a test substance to screen patients for response to oral vasodilators. Furthermore, inhalation of NO has been shown to improve gas exchange and right ventricular performance and to reduce the need for other, more invasive therapies in various settings of acute pulmonary hypertension. However, the improvement of arterial oxygenation seen in patients with the acute respiratory distress syndrome does not result in increased survival, questioning the future importance of inhaled NO in the treatment of this pulmonary disorder.

Acute respiratory distress syndrome

Outcome in acute respiratory distress syndrome (ARDS) is influenced by a number of factors, including the nature of the precipitating condition and the extent to which multiorgan failure ensues. Most studies of potential therapeutic interventions have been unsuccessful due to the enrollment of limited numbers of patients with a wide variety of pathologies of varying severity. Moreover, the value of initiating single-agent interventions at varying time points in what is an evolving and complex inflammatory process must be questioned. Mortality may therefore represent an inappropriate end-point for clinical trials, which are increasingly focusing on ventilator-free days. Despite these uncertainties, survival appears to be improving, possibly due to the application of supportive techniques in a protocol-driven fashion to patients in whom the underlying condition has been rigorously treated.