Hemodynamic and oxygenation changes of combined therapy with inhaled nitric oxide and inhaled aerosolized prostacyclin

Inhaled Pulmonary Vasodilators for the Treatment of Right Ventricular Failure in Cardio-Thoracic Surgery: Is One Better than the Others?

Right ventricular failure (RFV) is a potential complication following cardio-thoracic surgery, with an incidence ranging from 0.1% to 30%. The increase in pulmonary vascular resistance (PVR) is one of the main triggers of perioperative RVF. Inhaled pulmonary vasodilators (IPVs) can reduce PVR and improve right ventricular function with minimal systemic effects. This narrative review aims to assess the efficacy of inhaled nitric oxide and inhaled prostacyclins for the treatment of perioperative RVF. The literature, although statistically limited, supports the clinical similarity between them. However, it failed to demonstrate a clear benefit from the pre-emptive use of inhaled nitric oxide in patients undergoing left ventricular assist device implantation or early administration during heart-lung transplants. Additional concerns are related to cost safety and IPV use in pathologies associated with pulmonary venous congestion. The largest ongoing randomized controlled trial on adults (INSPIRE-FLO) is addressing whether inhaled Epoprostenol and inhaled nitric oxide are similar in preventing RVF after heart transplants and left ventricular assist device placement, and whether they are similar in preventing primary graft dysfunction after lung transplants. The preliminary analysis supports their equivalence. Several key points may be achieved by the present narrative review. When RVF occurs in the setting of elevated PVR, IPV should be the preferred initial treatment and they should be preventively used in patients at high risk of postoperative RVF. If severe refractory postoperative RVF occurs, IPVs should be combined with complementary pharmacology (inotropes and inodilators). If unsuccessful, right ventricular mechanical support should be established.

Nitric oxide versus epoprostenol for refractory hypoxemia in Covid-19

Objective

To compare the efficacy and outcomes with inhaled nitric oxide (iNO) and inhaled epoprostenol (iEPO) in patients with refractory hypoxemia due to COVID-19.

Design

Retrospective Cohort Study.

Setting

Single health system multicenter academic teaching hospitals.

Patients OR subjects

Age group of 18–80 years admitted to the medical ICU.

Interventions

Mechanically ventilated patients with COVID-19 infection, who received either iNO or iEPO between March 1^st, 2020, and June 30^th, 2020.

Measurements and main results

The primary outcome was the change in the PaO2/FiO2 (P/F) ratio 1 hour after initiation of pulmonary vasodilator therapy. Secondary outcomes include P/F ratios on days 1–3 after initiation, positive response in P/F ratio (increase of at least 20% in PaO2), total days of treatment, rebound hypoxemia (if there was a drop in oxygen saturation after treatment was stopped), ventilator free days (if any patient was extubated), days in ICU, days to extubation, days to tracheostomy, mortality days after intubation, 30-day survival and mortality. 183 patients were excluded, as they received both iNO and iEPO. Of the remaining 103 patients, 62 received iEPO and 41 received iNO. The severity of ARDS was similar in both groups. Change in P/F ratio at one hour was 116 (70.3) with iNO and 107 (57.6) with iEPO (Mean/SD). Twenty-two (53.7%) patients in the iNO group and 25 (40.3%) in the iEPO group were responders to pulmonary vasodilators n(%)(p = 0.152) (more than 20% increase in partial pressure of oxygen, Pao2), and 18 (43.9%) and 31 (50%) patients in the iNO and iEPO group (p = 0.685), respectively, had rebound hypoxemia. Only 7 patients in the cohort achieved ventilator free days (3 in the iEPO group and 4 in iNO group).

Conclusions

We found no significant difference between iNO and iEPO in terms of change in P/F ratio, duration of mechanical ventilation, ICU, in-hospital mortality in this cohort of mechanically ventilated patients with COVID-19. Larger, prospective studies are necessary to validate these results.

Comparison of inhaled nitric oxide with aerosolized prostacyclin or analogues for the postoperative management of pulmonary hypertension: a systematic review and meta-analysis

Background: This study aims to compare the effectiveness of inhaled prostacyclin or its analoguesversus nitric oxide (NO) in treating pulmonary hypertension (PH) after cardiac or pulmonary surgery remains unclear.Methods: PubMed, Cochrane, and Embase databases were searched for literature published prior to December 2019 using the following keywords: inhaled, nitric oxide, prostacyclin, iloprost, treprostinil, epoprostenol, Tyvaso, flolan, and pulmonary hypertension. Randomized controlled trials and multiple-armed prospective studies that evaluated inhaled NO versus prostacyclin (or analogues) in patients for perioperative and/or postoperative PH after either cardiac or pulmonary surgery were included. Retrospective studies, reviews, letters, comments, editorials, and case reports were excluded.Results: Seven studies with a total of 195 patients were included. No difference in the improvement of mean pulmonary arterial pressure (pooled difference in mean change= -0.10, 95% CI: -3.98 to 3.78, p = .959) or pulmonary vascular resistance (pooled standardized difference in mean change= -0.27, 95% CI: -0.60 to 0.05, p = .099) were found between the two treatments. Similarly, no difference was found in other outcomes between the two treatments or subgroup analysis.Conclusions: Inhaled prostacyclin (or analogues) was comparable to inhaled NO in treating PH after cardiac or pulmonary surgery.Key messagesThis study compared the efficacy of inhaled prostacyclin or its analogues versus inhaled NO to treat PH after surgery. The two types of agent exhibited similar efficacy in managing MPAP, PVR, heart rate, and cardiac output was observed.Inhaled prostacyclin may serve as an alternative treatment option for PH after cardiac or pulmonary surgery.

Management of Pulmonary Hypertension in the Operating Room

Pulmonary artery hypertension is defined as persistent elevation of mean pulmonary artery pressure > 25 mm Hg with pulmonary capillary wedge pressure < 15 mm Hg or elevation of exercise mean pulmonary artery pressure > 35 mm Hg. Although mild pulmonary hypertension rarely impacts anesthetic management, severe pulmonary hypertension and exacerbation of moderate hypertension can lead to acute right ventricular failure and cardiogenic shock. Knowledge of anesthetic drug effects on the pulmonary circulation is essential for anesthesiologists. Intraoperative management should include prevention of exacerbating factors such as hypoxemia, hypercarbia, acidosis, hypothermia, hypervolemia, and increased intrathoracic pressure; monitoring and optimizing right ventricular function; and treatment with selective pulmonary vasodilators. Recent advances in pharmacology provide anesthesiologists with a wide variety of options for selective pulmonary vasodilatation. Pulmonary hypertension is a major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement.

Clinical and Economic Impact of Formulary Conversion From Inhaled Flolan to Inhaled Veletri for Refractory Hypoxemia in Critically Ill Patients

BACKGROUND

Flolan (iFLO) and Veletri (iVEL) are 2 inhaled epoprostenol formulations. There is no published literature comparing these formulations in critically ill patients with refractory hypoxemia.

OBJECTIVE

To compare efficacy, safety, and cost outcomes in patients who received either iFLO or iVEL for hypoxic respiratory failure.

METHODS

This was a retrospective, single-center analysis of adult, mechanically ventilated patients receiving iFLO or iVEL for improvement in oxygenation. The primary end point was the change in the PaO2/FiO2 ratio after 1 hour of pulmonary vasodilator therapy. Secondary end points assessed were intensive care unit (ICU) length of stay (LOS), hospital LOS, duration of study therapy, duration of mechanical ventilation, mortality, incidence of adverse events, and cost.

RESULTS

A total of 104 patients were included (iFLO = 52; iVEL = 52). More iFLO patients had acute respiratory distress syndrome compared with the iVEL group (61.5 vs 34.6%; P = 0.01). There was no difference in the change in the PaO2/FiO2 ratio after 1 hour of therapy (33.04 ± 36.9 vs 31.47 ± 19.92; P = 0.54) in the iFLO and iVEL groups, respectively. Patients who received iVEL had a shorter duration of mechanical ventilation (P < 0.001) and ICU LOS (P < 0.001) but not hospital LOS (P = 0.86) and duration of therapy (P = 0.36). No adverse events were attributed to pulmonary vasodilator therapy, and there was no difference in cost.

CONCLUSIONS

We found no difference between iFLO and iVEL when comparing the change in the PaO2/FiO2 ratio, safety, and cost in hypoxic, critically ill patients. There were differences in secondary outcomes, likely a result of differences in underlying indication for inhaled epoprostenol.

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Perioperative management in patients with pulmonary hypertension

Patients with pulmonary hypertension (PH) are being encountered more commonly in the perioperative period and this trend is likely to increase as improvements in the recognition, management, and treatment of the disease continue to occur. Management of these patients is challenging due to their tenuous hemodynamic status. Recent advances in the understanding of the patho-physiology, risk factors, monitoring, and treatment of the disease provide an opportunity to reduce the morbidity and mortality associated with PH in the peri-operative period. Management of these patients requires a multi-disciplinary approach and meticulous care that is best provided in centers with vast experience in PH.

In this review, we provide a detailed discussion about oerioperative strategies in PH patients, and give evidence-based recommendations, when applicable.

Inhaled epoprostenol vs inhaled nitric oxide for refractory hypoxemia in critically ill patients

PURPOSE

The purpose of this is to compare efficacy, safety, and cost outcomes in patients who have received either inhaled epoprostenol (iEPO) or inhaled nitric oxide (iNO) for hypoxic respiratory failure.

MATERIALS AND METHODS

This is a retrospective, single-center analysis of adult, mechanically ventilated patients receiving iNO or iEPO for improvement in oxygenation.

RESULTS

We evaluated 105 mechanically ventilated patients who received iEPO (52 patients) or iNO (53 patients) between January 2009 and October 2010. Most patients received therapy for acute respiratory distress syndrome (iNO 58.5% vs iEPO 61.5%; P=.84). There was no difference in the change in the partial pressure of arterial O2/fraction of inspired O2 ratio after 1 hour of therapy (20.58±91.54 vs 33.04±36.19 [P=.36]) in the iNO and iEPO groups, respectively. No difference was observed in duration of therapy (P=.63), mechanical ventilation (P=.07), intensive care unit (P=.67), and hospital lengths of stay (P=.26) comparing the iNO and iEPO groups. No adverse events were attributed to either therapy. Inhaled nitric oxide was 4.5 to 17 times more expensive than iEPO depending on contract pricing.

CONCLUSIONS

We found no difference in efficacy and safety outcomes when comparing iNO and iEPO in hypoxic, critically ill patients. Inhaled epoprostenol is associated with less drug expenditure than iNO.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

[Effect of nebulised iloprost combined with inhaled nitric oxide and oral sildenafil on lung transplant patients. Therapeutic efficacy in pulmonary hypertension during surgery]

OBJECTIVES

There is a high incidence of pulmonary hypertension during the lung transplant peri-operative period, and could lead to a haemodynamic deterioration that may require the need of extracorporeal circulation. Our aim was to study the haemodynamic effects on the pulmonary and systemic circulation of the combination of inhaled nitric oxide and iloprost and oral sildenafil in patients with severe pulmonary hypertension during lung transplant surgery.

PATIENTS AND METHODS

Seventeen patients received 10μg of nebulised iloprost during the peri-operative period of the lung transplant when their mean pulmonary pressure exceeded 50mmHg. AU the patients received 50mg of oral sildenafil 30min before anaesthetic induction, 20ppm of inhaled nitric oxide after tracheal intubation. The haemodynamic and respiratory variables were recorded at baseline (after anaesthetic induction), prior to the administering of iloprost, and at 5 and 30min after it was given.

RESULTS

The administering of iloprost significantly reduced the pulmonary arterial pressure and significantly increases the cardiac Índex and the right ventrícular ejection fractíon. There were no signíficant changes occurred in the systemic arterial pressure.

CONCLUSIONS

The triple combination significantly reduces the pulmonary pressures in the lung transplant peri-operative and should be considered when there is severe pulmonary hypertension during the surgery or during the immediate post-operative period of lung transplantation.

Inhaled nitric oxide and inhaled prostacyclin in acute respiratory distress syndrome: what is the evidence?

The mortality for acute respiratory distress syndrome remains unacceptably high. Two vasodilators, inhaled prostacyclin and inhaled nitric oxide, are reviewed in this article. Knowledge of inhaled prostacyclin has grown substantially in the past 30 years, but less research exists about its utility in acute respiratory distress syndrome. Inhaled prostacyclin and other prostaglandin derivatives are used in acute respiratory distress syndrome with increasing frequency. Currently, only randomized controlled trials exist for inhaled nitric oxide in acute respiratory distress syndrome patients. Randomized controlled trials with consistent dosing methods are needed for both vasodilators to better define their role in the treatment of acute respiratory distress syndrome.

Endurance training increases exercise-induced prostacyclin release in young, healthy men--relationship with VO2max

In the present study, we evaluated the effect of 5 weeks of moderate-intensity endurance training on the basal and exercise-induced systemic release of prostacyclin (PGI(2)), as assessed by plasma 6-keto-PGF(1 alpha) concentration. Twelve physically active young men with the following characteristics participated in this study (the mean +/- SD): age, 22.7 +/- 2.0 years; body mass, 76.8 +/- 8.9 kg; BMI, 23.48 +/- 2.17 kg x m(-2); and maximal oxygen uptake (VO(2 max)), 46.1 +/- 4.0 ml x kg(-1) x min(-1). Plasma 6-keto-PGF(1 alpha) concentrations were measured in venous blood samples taken prior to the exercise and at exhaustion (at VO(2 max)) before and after completing the training protocol. On average, the training resulted in a significant increase in VO(2 max) (p = 0.03), power output at VO(2 max) (p = 0.001) and a significant increase (p = 0.05) in the net-exercise-induced increase in plasma 6-keto-PGF(1 alpha) concentration (Delta 6-keto-PGF(1 alpha) i.e., the difference between the end-exercise and pre-exercise 6-keto-PGF(1 alpha) concentrations). No effect of training on the basal PGI(2) concentration was found. Interestingly, within the study sample (n = 12), two subgroups could be defined with a differential pattern of response with respect to Delta 6-keto-PGF(1 alpha) concentrations. In one subgroup (n = 7), a significant increase in Delta 6-keto-PGF(1 alpha) concentration after training was found (p < 0.02) (responders). This enhancement in the exercise-induced PGI(2) release was accompanied by a significant (p < 0.05) increase in VO(2 max) after training. In contrast, in another subgroup (n = 5), there was no observed effect of training on the Delta 6-keto-PGF(1 alpha) concentration and the VO(2 max) after training (non-responders). In both of these subgroups, training did not influence the basal PGI(2) concentration. In conclusion, the endurance training resulted in the adaptive augmentation of the systemic release of PGI(2) in response to exercise, which plays a role in the training-induced increase in VO(2 max) in young, healthy men. The impairment of the training-induced augmentation of PGI(2) release in response to exercise demonstrated in the non-responders subgroup may predispose them to increased cardiovascular risk during vigorous exercise.

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

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

Inhaled alternatives to nitric oxide

OBJECTIVE

Inhaled nitric oxide has gained an established place in the management of pulmonary hypertension. However, cost, potential toxicity, and the lack of positive outcome data with inhaled nitric oxide therapy has generated interest in alternative inhaled, selective pulmonary vasodilators. This article describes those alternatives that have been studied to date.

DESIGN

Literature review of inhaled, selective pulmonary vasodilators other than nitric oxide.

METHODS

A review of the molecular mechanisms, potential side effects, and the studies to date in both animal models and clinical studies describing the physiologic effects of alternative agents to inhaled nitric oxide.

CONCLUSION

There are a number of available agents that have comparable physiologic effects as inhaled nitric oxide. The best studied of these are the inhaled prostanoids (prostacyclin and iloprost), and there is growing interest in novel therapies such as phosphodiesterase inhibitors and neuropeptides.

Inhaled prostacyclin is safe, effective, and affordable in patients with pulmonary hypertension, right heart dysfunction, and refractory hypoxemia after cardiothoracic surgery

BACKGROUND

The purpose of this study was to describe our institutional experience in using inhaled prostacyclin as a selective pulmonary vasodilator in patients with pulmonary hypertension, refractory hypoxemia, and right heart dysfunction after cardiothoracic surgery.

METHODS

Between February 2001 and March 2003, cardiothoracic surgical patients with pulmonary hypertension (mean pulmonary artery pressure >30 mm Hg or systolic pulmonary artery pressure >40 mm Hg), hypoxemia (PaO(2)/fraction of inspired oxygen <150 mm Hg), or right heart dysfunction (central venous pressure >16 mm Hg and cardiac index <2.2 L.min(-1).m(-2)) were prospectively administered inhaled prostacyclin at an initial concentration of 20,000 ng/mL and then weaned per protocol. Hemodynamic variables were measured before the initiation of inhaled prostacyclin, 30 to 60 minutes after initiation, and again 4 to 6 hours later.

RESULTS

One hundred twenty-six patients were enrolled during the study period. At both time points, inhaled prostacyclin significantly decreased the mean pulmonary artery pressure without altering the mean arterial pressure. The average length of time on inhaled prostacyclin was 45.6 hours. There were no adverse events attributable to inhaled prostacyclin. The average cost for inhaled prostacyclin was 150 US dollars per day. Compared with nitric oxide, which costs 3000 US dollars per day, the potential cost savings over this period were 681,686 US dollars.

CONCLUSIONS

Inhaled prostacyclin seems to be a safe and effective pulmonary vasodilator for cardiothoracic surgical patients with pulmonary hypertension, refractory hypoxemia, or right heart dysfunction. Overall, inhaled prostacyclin significantly decreases mean pulmonary artery pressures without altering the mean arterial pressure. Compared with nitric oxide, there is no special equipment required for administration or toxicity monitoring, and the cost savings are substantial.

[Aerosolized and intravenous prostacyclin during one-lung ventilation. Hemodynamic and pulmonary effects]

BACKGROUND

One-lung ventilation is frequently used in thoracic surgery. However, hypoxic pulmonary vasoconstriction of the atelectatic lung may produce pulmonary hypertension. The objective of the present study was to compare the acute effects of intravenous versus aerosolized prostacyclin (PGI(2)) on pulmonary and systemic circulation.

METHODS

PGI(2) was administered in 11 anesthetized and unilaterally ventilated pigs by infusion (5, 10, and 20 ng/kg body weight/min) and by inhalation (4, 8, and 16 ng/kg body weight/min) in a cross-over design.

RESULTS

Infusion of PGI(2) reduced both pulmonary (PVR) and systemic vascular resistance (SVR). Due to a concomitant increase in cardiac index (CI) mean arterial (MAP) and pulmonary artery pressures (MPAP) did not change significantly. In contrast, aerosolized PGI(2) produced a significant decrease in PVR (-21.4 to -32.8%) and MPAP (-12.0 to -17.8%) without affecting SVR, MAP, and CI. Arterial oxygenation tension (p(a)O(2)) was not affected.

CONCLUSION

During one-lung ventilation only aerosolized prostacyclin produced a selective pulmonary vasodilation.

Alternatives to nitric oxide

Inhaled nitric oxide (INO) is a selective pulmonary vasodilator that has the ability to produce vasodilation in the pulmonary vascular bed without causing it in the systemic circulation. This property of INO has made it a useful therapy in the management of both adult and paediatric patients with a variety of conditions associated with pulmonary hypertension (PH), with or without hypoxia. Toxicity, cost and negative-outcome studies have prompted a search for alternative agents. These include inhaled prostacyclin and alternative prostaglandin preparations such as inhaled iloprost, treprostinol and beraprost. The phospodiesterase inhibitors show real potential in the management of both acute and chronic forms of PH, and antagonists of endogenous pulmonary vasoconstrictors, such as endothelin and thromboxane, are being evaluated for the long-term treatment of conditions such as primary pulmonary hypertension.

Anaesthesia in patients with cystic fibrosis

Cystic fibrosis is an autosomal-recessive disorder. In 1989 the gene mutation that causes cystic fibrosis was localized on the long arm of chromosome 7. Cystic fibrosis occurs in 1/2000 children and the majority now reach adulthood. In view of numerous clinical manifestations of cystic fibrosis, these patients frequently require surgery. Cystic fibrosis is therefore of increasing interest to anaesthesiologists. Preoperative assessment is reviewed. Pre-, intra- and postoperative care must be directed toward optimal clearance of viscous respiratory secretions, and should minimize the risk of postoperative respiratory complications. All procedures should be planned but it is very important to prepare patients for surgery, with daily physiotherapy, administration of therapeutic agents using aerosols, management of nutrition and pancreatic enzymes, and administration of vitamins and antibiotics if indicated. Currently, anaesthesia can safely be carried out in cystic fibrosis patients undergoing minor surgery, with very low incidence of postoperative respiratory complications. Finally, organ transplantation, and in particular lung transplantation, with all its attendant anaesthesiological implications, has improved the outcome for many patients with cystic fibrosis.

Intra-operative use of inhaled vasodilators: are there indications?

The US Food and Drug Administration and European authorities have recently approved inhaled nitric oxide for the treatment of neonates with hypoxic respiratory failure associated with pulmonary hypertension. In addition to this highly specific condition, there is an increasing 'off-label' use of inhaled nitric oxide and other inhaled vasodilators in the perioperative setting. Potential indications include right heart failure as a result of acute pulmonary hypertension in cardiac and non-cardiac surgery, the prevention of reperfusion injury in lung transplantation, the treatment of hypoxaemia during single-lung ventilation, and more recently, the treatment of sickle cell crisis.

Searching the ideal inhaled vasodilator: from nitric oxide to prostacyclin

Today, the technique to directly administer vasodilators via the airway to treat pulmonary hypertension and to improve pulmonary gas exchange is widely accepted among clinicians. The flood of scientific work focussing on this new therapeutic concept had been initiated by a fundamental new observation by Pepke-Zaba [1]and Frostell in 1991 [2]: Both scientists reported, that inhalation of exogenous nitric oxide (NO) gas selectively dilates pulmonary vessels without a concomittant systemic vasodilation. No more than another decade ago NO was identified as an important endogenous vasodilator [3]while having merely been regarded an environmental pollutant before that time. Although inhaled NO proved to be efficacious, alternatives were sought-after due to NO's potential side-effects. In search for the ideal inhaled vasodilator another group of endogenous mediators -- the prostanoids -- came into the focus of interest. The evidence for safety and efficacy of inhaled prostanoids is -- among a lot of other valuable work -- based on a series of experimental and clinical investigations that have been performed or designed at the Institute for Surgical Research under the guidance and mentorship of Prof. Dr. med. Dr. h.c. mult. K. Messmer [4-19]. In the following, the current and newly emerging clinical applications of inhaled prostanoids and the experimental data which they are based on, will be reviewed.