Recent advances in pulmonary vascular disease

Sildenafil for pulmonary hypertension in neonates

BACKGROUND

Persistent pulmonary hypertension in the neonate (PPHN) is associated with high mortality. Currently, the therapeutic mainstay for PPHN consists of assisted ventilation and administration of inhaled nitric oxide (iNO). However, nitric oxide is costly, and its use may not be appropriate in resource-poor settings. Approximately 30% of patients fail to respond to iNO. High concentrations of phosphodiesterases in the pulmonary vasculature have led to the use of phosphodiesterase inhibitors such as sildenafil or milrinone.

OBJECTIVES

To assess the efficacy and safety of sildenafil for treatment of pulmonary hypertension in neonates.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 3), MEDLINE via PubMed (1966 to 18 April 2017), Embase (1980 to 18 April 2017), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 18 April 2017). We searched clinical trials databases, conference proceedings, and reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials of sildenafil compared with placebo or other pulmonary vasodilators, irrespective of dose, route, and duration of administration, in neonates with pulmonary hypertension, if investigators reported any of the prespecified outcomes.

DATA COLLECTION AND ANALYSIS

We assessed the methodological quality of trials regarding how bias was minimised at study entry, during study intervention, and at outcomes measurement. We extracted data on relevant outcomes; we estimated the effect size and reported it as risk ratio (RR), risk difference (RD), or mean difference (MD), as appropriate. We applied the I2 test of heterogeneity and used GRADE to assess the quality of evidence.

MAIN RESULTS

For this update, we identified two additional studies, for a total of five eligible trials that enrolled 166 infants. The methodological quality of these studies ranged from low to high risk of bias. Three studies were performed in resource-limited settings, where iNO and high-frequency ventilation were not available at the time of the study. One study compared sildenafil versus active controls, and another study evaluated sildenafil as adjuvant therapy to iNO. When comparing sildenafil with placebo, investigators noted significant reduction in mortality in the sildenafil alone group (three studies, 77 participants; typical RR 0.20, 95% confidence interval (CI) 0.07 to 0.56; I2 = 0% - none; typical RR -0.36, 95% CI -0.53 to -0.18; number needed to treat for an additional beneficial outcome 3, 95% CI 2 to 6; I2 = 39% - low). Trials reported no significant differences in mortality upon comparison of the sildenafil group versus the active control group (one study, 65 participants; typical RR 0.55, 95% CI 0.05 to 5.75), or when iNO was administered to both groups (one study, 24 participants; typical RR 1.27, 95% CI 0.26 to 6.28). Physiological parameters of oxygenation (oxygenation index, partial pressure of oxygen in arterial blood (PaO2)) suggested steady improvement after the first dose of sildenafil. None of the included trials identified any clinically important side effects. We rated the quality of evidence as low to very low owing to imprecision related to small sample size and unclear methodological features.

AUTHORS' CONCLUSIONS

Sildenafil used for treatment of pulmonary hypertension has potential for reducing mortality and improving oxygenation in neonates, especially in resource-limited settings where iNO is not available. However, large-scale randomised trials comparing sildenafil versus active controls (other pulmonary vasodilators) and providing follow-up for survivors are needed to assess the comparative effectiveness and long-term safety of sildenafil versus other pulmonary vasodilators.

Hydralazine in infants with persistent hypoxemic respiratory failure

BACKGROUND

Most deaths of infants with chronic lung disease (CLD) are caused by respiratory failure, unremitting pulmonary artery hypertension (PAH) with cor pulmonale, or infection. Although the exact prevalence of PAH in infants with CLD is unknown, infants with CLD and severe PAH have a high mortality rate. Except for oxygen supplementation, no specific interventions have been established as effective in the treatment for PAH in premature infants with CLD. Little has been proven regarding the clinical efficacy of vasodilators and concerns remain regarding adverse effects.

OBJECTIVES

To review current evidence for the benefits and harms of hydralazine therapy to infants with persistent hypoxemic respiratory failure.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE via PubMed and EMBASE, and other clinical trials registries through November 2011 using the standard search strategy of the Cochrane Neonatal Review Group. We searched these databases using a strategy combining a variation of the Cochrane highly sensitive search strategy for identifying randomised trials in MEDLINE; sensitivity-maximising version with selected MeSH and free-text terms: hydralazine, vasodilator agent, antihypertensive agent, heart diseases, lung diseases, respiratory tract diseases, infant, and randomised controlled trial.

SELECTION CRITERIA

We considered only randomised controlled trials and quasi-randomised trials for inclusion. We included low birth weight (LBW) infants with persistent hypoxemic respiratory failure who were treated with any type of hydralazine therapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality according to pre-specified criteria.

MAIN RESULTS

We found no studies meeting the criteria for inclusion in this review.

AUTHORS' CONCLUSIONS

There was insufficient evidence to determine the safety and efficacy of hydralazine in LBW infants with persistent hypoxemic respiratory failure. Since hydralazine is inexpensive and potentially beneficial, randomised controlled trials are recommended. Such trials are particularly needed in settings where other medications such as sildenafil, inhaled nitric oxide (iNO), or extracorporeal membrane oxygenation (ECMO) are not available.

Inhalation therapy to treat pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vascular system, which may lead to right-heart failure or early death in the absence of effective treatment. The current therapy for PAH mainly includes phosphodiesterase inhibitors, prostanoids and endothelin receptor antagonists. These, however, have adverse effects when administered via conventional routes. There is a clear and critical need for the development of a novel delivery system that can efficiently deliver the drug to lung vasculature and minimize adverse effects. This article summarizes the inhalation devices and recent patents in the area of inhalable therapy for the treatment of PAH. Various patents are discussed that describe the application of inhalable therapy to target lung vasculature and to reduce dose-related side effects in PAH treatment. Entry of some inhalable delivery approaches into clinical trials is the result of progress in inhalable therapies for the treatment of PAH.

Sildenafil for pulmonary hypertension in neonates

BACKGROUND

Persistent pulmonary hypertension in neonates (PPHN) is associated with high mortality. Currently, the therapeutic mainstay for PPHN is assisted ventilation and administration of inhaled nitric oxide (iNO). However, nitric oxide is costly and may not be appropriate in resource-poor settings. Approximately 30% of patients fail to respond to iNO. High concentrations of phosphodiesterases in the pulmonary vasculature has led to the use of phosphodiesterase inhibitors such as sildenafil or milrinone.

OBJECTIVES

To assess the efficacy and safety of sildenafil in the treatment of persistent pulmonary hypertension in neonates.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL databases were searched from their inception until December 2010; Clinicaltrials.gov web site, the reference lists of identified trials, and abstracts of meetings were searched without any language restriction.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of sildenafil compared with placebo or other pulmonary vasodilators, irrespective of dose, route and duration of administration in neonates with PPHN, were included if the trial reported any of the pre-specified outcomes.

DATA COLLECTION AND ANALYSIS

The methodological quality of the trials was assessed regarding how bias was minimized at study entry, during study intervention and at outcomes measurement. Data on relevant outcomes were extracted and the effect size was estimated and reported as relative risk (RR), risk difference (RD) and weighted mean difference (MD) as appropriate. The I-squared (I(2)) test of heterogeneity was applied.

MAIN RESULTS

Three eligible trials that enrolled 77 infants were identified. The methodological quality of the studies indicated low-moderate risk of bias. All studies were performed in resource-limited settings where iNO and high frequency ventilation were not available at the time of study. There was significant reduction in mortality in the sildenafil group (typical RR 0.20, 95% CI 0.07 to 0.57; typical RD -0.38, 95% CI -0.60 to -0.16; Number needed to treat to benefit 3, 95% CI 2 to 6). Physiological parameters of oxygenation (oxygenation index, PaO(2)) suggested a steady improvement after the first dose of sildenafil. No clinically important side effects were identified.

AUTHORS' CONCLUSIONS

Sildenafil in the treatment of PPHN has significant potential especially in resource limited settings. However, a large scale randomised trial comparing sildenafil with the currently used vasodilator, inhaled nitric oxide, is needed to assess efficacy and safety.

Sildenafil therapy for neonatal and childhood pulmonary hypertensive vascular disease

OBJECTIVES

We hypothesised that sildenafil would improve hemodynamics in children with pulmonary hypertension and attenuate rebound pulmonary hypertension after inhaled nitric oxide withdrawal.

PATIENTS AND METHODS

We undertook an open-label, single-drug study of sildenafil in patients under 5 years of age with either symptomatic or rebound pulmonary hypertension following inhaled nitric oxide withdrawal.

RESULTS

We recruited 25 patients (median age 180 days, 10-1790) to receive sildenafil. The median right ventricular to systemic systolic blood pressure ratio before sildenafil therapy was 1.0 (0.5-1.4) and decreased to 0.5 (with a range from 0.3 to 1.3; p = 0.0002). In five patients the baseline pulmonary vascular resistance index was 10 (7.1-13.6) Wood units metre square and decreased to 5.8 (2.7-15.6) Wood units metre square (p = 0.04) at 6 months. Ten patients were treated with sildenafil for a median of 34 days (9-499) until resolution of pulmonary artery hypertension and continue to do well. Six patients continued sildenafil therapy for a median of 1002 days (384-1574) with improvement but without resolution of pulmonary hypertension. There was no change in serum creatinine, urea, liver function tests, or platelet count. In 15 patients sildenafil abolished rebound pulmonary artery hypertension following withdrawal of inhaled nitric oxide. Median right ventricular pressure to systemic systolic pressure ratio decreased from 1.0 (0.8-1.4) during nitric oxide withdrawal to 0.4 (0.3-0.8) p = 0.006 after pre-treatment with sildenafil.

CONCLUSION

In children under 5 years of age with severe pulmonary hypertension, sildenafil therapy resulted in prolonged hemodynamic improvements without adverse effects. Sildenafil attenuated rebound pulmonary hypertension after withdrawal of inhaled nitric oxide.

Receptor tyrosine kinase inhibitors in rodent pulmonary hypertension

Pulmonary hypertension (PH) is a disorder characterized by vascular remodeling and proliferation, a phenotype dependent upon unimpeded growth factor and kinase pathway activation with strong similarities to malignant tumors. This chapter details our novel application of the multikinase inhibitor, sorafenib, in rodent models of PH to improved hemodynamic parameters and attenuates PH structural changes1. Sorafenib is a Raf kinase inhibitor and our biochemical and genomic evidence supported the potential involvement of the MAPK cascade system and TGFB3 in PH development and the response to therapy. Integration of expression genomic analyses coupled with intense bioinformatics identified gene expression and ontology signatures in the development of PH and implicated the role of cytoskeletal protein such as caldesmon or nmMLCK as potentially key participants in PH-induced vascular remodeling and proliferation. Our studies suggest the PKI sorafenib as a potentially novel treatment for severe PH with the MAPK cascade a potential canonical target profoundly effecting vascular cytoskeletal -rearrangements and remodeling1.

Genomic assessment of a multikinase inhibitor, sorafenib, in a rodent model of pulmonary hypertension

Pulmonary hypertension (PH) and cancer pathology share growth factor- and MAPK stress-mediated signaling pathways resulting in endothelial and smooth muscle cell dysfunction and angioproliferative vasculopathy. In this study, we assessed sorafenib, an antineoplastic agent and inhibitor of multiple kinases important in angiogenesis [VEGF receptor (VEGFR)-1-3, PDGF receptor (PDGFR)-beta, Raf-1 kinase] as a potential PH therapy. Two PH rat models were used: a conventional hypoxia-induced PH model and an augmented PH model combining dual VEGFR-1 and -2 inhibition (SU-5416, single 20 mg/kg injection) with hypoxia. In addition to normoxia-exposed control animals, four groups were maintained at 10% inspired O(2) fraction for 3.5 wk (hypoxia/vehicle, hypoxia/SU-5416, hypoxia/sorafenib, and hypoxia/SU-5416/sorafenib). Compared with normoxic control animals, rats exposed to hypoxia/SU-5416 developed hemodynamic and histological evidence of severe PH while rats exposed to hypoxia alone displayed only mild elevations in hemodynamic values (pulmonary vascular and right ventricular pressures). Sorafenib treatment (daily gavage, 2.5 mg/kg) prevented hemodynamic changes and demonstrated dramatic attenuation of PH-associated vascular remodeling. Compared with normoxic control rats, expression profiling (Affymetrix platform) of lung RNA obtained from hypoxia [false discovery rate (FDR) 6.5%]- and hypoxia/SU-5416 (FDR 1.6%)-challenged rats yielded 1,019 and 465 differentially regulated genes (fold change >1.4), respectively. A novel molecular signature consisting of 38 differentially expressed genes between hypoxia/SU-5416 and hypoxia/SU-5416/sorafenib (FDR 6.7%) was validated by either real-time RT-PCR or immunoblotting. Finally, immunoblotting studies confirmed the upregulation of the MAPK cascade in both PH models, which was abolished by sorafenib. In summary, sorafenib represents a novel potential treatment for severe PH with the MAPK cascade a potential canonical target.

Sildenafil for pulmonary hypertension in neonates

BACKGROUND

Persistent pulmonary hypertension in neonates (PPHN) is associated with high mortality. Currently, the therapeutic mainstay for PPHN is assisted ventilation and administration of inhaled nitric oxide (iNO). However, nitric oxide is costly and may not be appropriate in resource-poor settings. Approximately 30% of patients fail to respond to iNO. High concentrations of phosphodiesterases in the pulmonary vasculature has led to the use of phosphodiesterase inhibitors such as sildenafil or milrinone.

OBJECTIVES

To assess the efficacy and safety of Sildenafil in the treatment of persistent pulmonary hypertension in neonates.

SEARCH STRATEGY

MEDLINE, EMBASE, CINAHL databases were searched from their inception until March 2007; the Cochrane Central Register of Controlled Trials, the Cochrane Library, the reference lists of identified trials, and abstracts of meetings were searched without any language restriction.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of Sildenafil compared with placebo or other pulmonary vasodilators, irrespective of dose, route and duration of administration in neonates with PPHN, were included if the trial reported any of the pre-specified outcomes.

DATA COLLECTION AND ANALYSIS

The methodological quality of the trials was assessed regarding how bias at study entry, study intervention and outcomes measurement was minimized. Data on relevant outcomes were extracted and the effect size was estimated and reported as relative risk (RR), risk difference (RD) and weighted mean difference (MD) as appropriate. The I-squared (I(2)) test of heterogeneity was applied.

MAIN RESULTS

Two small eligible trials (one full article and one abstract) were identified. The methodological quality of the trial presented in the full article was good. Information provided in the abstract was limited. The total number of enrolled patients in the two studies was 37. Both studies were performed in resource-limited settings where iNO and high frequency ventilation are not available. Both studies reported statistically significant improvement in oxygenation (reduction in oxygenation index) in the Sildenafil group. One study reported what would be, if replicated, a strongly protective effect on mortality (RR 0.17, 95% CI 0.03, 1.09) favoring the Sildenafil group. However, this result needs to be replicated in larger studies. No clinically important side effects were reported.

AUTHORS' CONCLUSIONS

The safety and effectiveness of sildenafil in the treatment of PPHN has not yet been established and its use should be restricted within the context of randomized controlled trials. Further randomized controlled trials of adequate power comparing Sildenafil with other pulmonary vasodilators are needed in moderately ill infants with PPHN.

CT of the chest in the evaluation of idiopathic pulmonary arterial hypertension in children

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is a rare disease in children. By definition it is a diagnosis of exclusion, and CT of the chest is primarily performed to exclude other causes. Previous studies have defined CT features suggestive of the diagnosis of IPAH, but these have all been limited to the adult population.

OBJECTIVE

Contrast-enhanced chest CT and high-resolution CT findings in IPAH were evaluated in an attempt to define features consistently seen in children with this condition.

MATERIALS AND METHODS

The chest CT scans performed at initial presentation were reviewed in 17 children with echocardiographic or angiographic evidence of IPAH.

RESULT

There were nine boys and eight girls, ranging in age from 1 month to 17 years. The extrapulmonary findings included cardiomegaly with right-sided cardiac enlargement, which was seen in 13 children. The central pulmonary arteries were enlarged in 15 children, with peripheral enlargement in two. In six children this resulted in bronchial compression. In addition, mediastinal and hilar lymphadenopathy was noted in three children. Prominent intrapulmonary features included a peripheral vasculopathy, with enlarged tortuous vessels, seen in eight children. Ill-defined ground-glass centrilobular opacities were also noted in eight children, representing the most common parenchymal abnormality. Other findings included septal lines in five, diffuse ground-glass opacification in four and focal hyperlucent zones in three. Mosaic attenuation was seen in one child.

CONCLUSION

A variety of imaging findings are identified in IPAH. Features particularly consistent with the diagnosis include peripheral vasculopathy and centrilobular opacities in the setting of cardiomegaly and central pulmonary arterial enlargement.

Hypoxemic Fetoplacental Vasoconstriction: A Graduated Response to Reduced Oxygen Conditions in the Human Placenta

We investigated the characteristics of hypoxemic fetoplacental vasoconstriction (HFPV) in the dual perfused, single isolated human placental cotyledon. Fetal arterial blood pressures (FAP) were measured in four cotyledons (Group 1) equilibrated with 21% oxygen (O2), 5% carbon dioxide (CO2), and nitrogen (N2) [control] followed by 5% CO2 in N2 for 30 min. FAP (mean +/- sd) increased from 69.8 (+/- 6.4) to 105 (+/- 3.0) mm Hg (P < 0.05), confirming the utility of HFPV in the human placenta. Eight more cotyledons (Group 2) were exposed sequentially and alternately at 15-min intervals to the control gases and to gas blends containing 15%, 12%, 5%, and 0% O2 with 5% CO2 and N2. FAP increased significantly (P < 0.05) in a stepwise fashion from 68.7 (+/- 3.7) to 70.5 (+/- 3.3) mm Hg with 15% O2; from 69.3 (+/- 3.8) to 72.4 (+/- 4.3) mm Hg with 12% O2; from 67.8 (+/- 3.2) to 74.5 (+/- 3.4) mm Hg with 5% O2; and from 69.7 (+/- 3.4) to 77.9 (+/- 5.9) mm Hg with 0% O2, suggesting that HFPV is a graduated response to reduced O2 conditions in the human placenta.

HIV-1 TAT represses transcription of the bone morphogenic protein receptor-2 in U937 monocytic cells

The bone morphogenetic protein receptor-2 (BMPR2) is a member of the transforming growth factor-beta receptor family and is expressed on the surface of several cell types including endothelial cells and macrophages. Recently, a cause for familial primary pulmonary hypertension (FPPH) has been identified as mutations in the gene encoding BMPR2. Three forms of pulmonary hypertension (PH) exist, including PPH, FPPH, and PH secondary to other etiologies (sporadic PH) such as drug abuse and human immunodeficiency virus (HIV) infection. It is interesting that these subtypes are histologically indistinguishable. The macrophage is a key target cell for HIV-1, significantly altering macrophage cell function upon infection. HIV-1 trans-activator of transcription (Tat), an immediate-early product of the HIV-1 lifecycle, plays an important role in mediating HIV-induced modulation of host cell function. Our laboratory has previously shown that Tat represses mannose receptor transcription in macrophages. In the current study, we examined activity from the BMPR2 promoter in the macrophage cell line U937 and potential regulation by Tat. Transfection of U937 cells with BMPR2 promoter-reporter constructs revealed dose-dependent repression of BMPR2 promoter activity in the presence of Tat. Experiments using truncations of the BMPR2 promoter localized Tat-mediated repression to the first 208 bases of the promoter. Decreased BMPR2 transcription resulted in altered downstream signaling. Similar to mothers against decapentaplegics (SMAD) phosphorylation and SMAD6 expression, in response to BMP2 treatment, were down-regulated after Tat treatment. Finally, HIV-1 infection and treatment with Tat protein of the U937 human monocytic cell line resulted in a decreased, endogenous BMPR2 transcript copy number.

Recent advances in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect which continues to challenge paediatric surgeons and intensivists. Affecting approximately 1:2500 births, a baby with CDH is born every 24-36 hours in the UK.

Phosphodiesterase Inhibitors and Persistent Pulmonary Hypertension of the Newborn

This continuing feature will focus on recent advancements in the areas of pediatrics and neonatal pharmacology and on methods for reducing medication error risk in this patient population. Most pharmacological agents are designed with the adult in mind, and there is little literature-based data from which to derive dosing schedules and proper drug administration techniques for the pediatric and neonatal patient. Moreover, pharmacological response in this group is not well understood. We hope that this feature will help you provide pharmaceutical care to this high-risk population. Direct questions or comments to hospitalpharmacy@drugfacts.com .

What you should know about pulmonary hypertension

Pulmonary hypertension is a fatal disease that often goes unrecognized until it becomes severe and debilitating. Early recognition allows for earlier treatment and improved quality of life for those affected. Early signs and symptoms include dyspnea and fatigue, and treatment options range from oral therapy with bosentan to intravenous therapy with epoprostenol. Work-up of pulmonary hypertension and its secondary causes are also reviewed.

Hypothesis: selective phosphodiesterase-5 inhibition improves outcome in preeclampsia

The pathogenesis of preeclampsia stems from aberrant changes at the placental interface. The trophoblastic endovascular invasion of tonic spiral arteries that converts them to passive conduits falters. Uteroplacental insufficiency and fetoplacental hypoxemia result. Secondary maternal oxidative stress and an excessive inflammatory response to pregnancy generate the clinical syndrome of preeclampsia. Current treatment focuses on preventing seizures, controlling hypertension, preserving renal function and delivering the baby. We propose that the pathophysiological changes induced by preeclampsia in the placenta parallel those caused by persistent hypoxemia in the lungs at high altitude or with chronic obstructive pulmonary disease. Unrelenting pulmonary hypoxic vasoconstriction induces pulmonary hypertension and cor pulmonale. Inhalation of nitric oxide and phosphodiesterase-5 inhibitors opposes pulmonary hypoxic vasoconstriction, alleviates pulmonary hypertension and improves systemic oxygenation. Notably nitric oxide donor therapy also counters hypoxemic fetoplacental vasoconstriction, a biological response analogous to pulmonary hypoxic vasoconstriction. Fetal oxygenation and nutrition improve. Placental upstream resistance to umbilical arterial blood flow decreases. Fetal right ventricular impedance falls. Heart failure (cor placentale) is avoided. Emergency preterm delivery can be postponed. Other than low dose aspirin and antioxidants vitamins C and E no available therapy specifically targets the underlying disease profile. We hypothesize that, like nitric oxide donation, pharmacological inhibition of placental phosphodiesterase-5 will also protect the fetus but for a longer time. Biological availability of guanosine 3'5'-cyclic monophosphate is boosted due to slowed hydrolysis. Adenosine 3'5'-cyclic monphosphate levels increase in parallel. Cyclic nucleotide accumulation dilates intact tonic spiral arteries and counters hypoxemic fetoplacental vasoconstriction. Intervillous and intravillous perfusion pick up. Maternal to fetal placental circulatory matching improves. Enhanced placental oxygen uptake alleviates hypoxemic fetal stress. Appropriate fetal nutrition resumes. Cor placentale and severe intrauterine growth restriction are averted. Increased maternal cyclic nucleotide concentrations promote systemic vasodilatation so that blood pressures fall. Preemption of oxidative stress initiated by "consumptive" oxidation of nitric oxide stabilizes the vascular endothelium and corrects coagulopathy. Anti-inflammatory and immunosuppressant adenosine 3'5'-cyclic monphosphate offsets the extreme gestational inflammatory response. Cellular injury and multi-organ damage are prevented. One tablet a day of the new long acting phosphodiesterase-5 inhibitor, tadalafil (half life of 17.5 h) theoretically should allow a preterm pregnancy affected by preeclampsia to continue safely. Selective monitoring of vital organ functions guards against life-threatening maternal complications. Regular biophysical profiling warns the obstetrician of impending fetal compromise. Fetal growth and vital organ maturation can continue. As a result workloads imposed upon neonatal intensivists will lighten. Parental anxiety and concern will be allayed. The cost of treating preeclamptic mothers and their extremely low birth weight infants will decrease. Money saved by midwifery services in poorer states can be used to pay for better prenatal care. Severe preeclampsia/eclampsia will be less common. Maternal and perinatal morbidity and mortality will be reduced. Because the human immunodeficiency virus often infects individuals at a workforce eligible age, the global acquired immunodeficiency syndrome pandemic has already brought many nations to the brink of economic ruin. Potentially productive lives saved for the future will help restore them fiscally.

Phosphodiesterase inhibitors for persistent pulmonary hypertension of the newborn: a review

Persistent pulmonary hypertension of the newborn (PPHN) is a complex syndrome with multiple causes, with an incidence of 0.43-6.8/1,000 live births and a mortality of 10-20%. Survivors have high morbidity in the forms of neurodevelopmental and audiological impairment, cognitive delays, hearing loss, and a high rate of rehospitalization. The optimal approach to the management of PPHN remains controversial. Inhaled nitric oxide (iNO) is currently regarded as the gold standard therapy, but with as many as 30% of cases failing to respond, has not proven to be the single magic bullet. Given the complex pathophysiology of the disease, any such magic bullet is unlikely. A number of recent studies have suggested a role for specific phosphodiesterase (PDE) inhibitors in the management of PPHN. Sildenafil, a specific PDE5 inhibitor, appears the most promising of such agents. We aim to review the current status and limitations of iNO and the potential of PDE inhibitors in the management of PPHN. The reasons why caution is warranted before specific PDE5 inhibitors like sildenafil are labelled as potential magic bullets for PPHN will be discussed. The need for randomized-controlled trials to determine the safety, efficacy, and long-term outcome following treatment with sildenafil in PPHN is emphasized.

Critical care in cardiovascular medicine

The field of cardiac intensive care is rapidly evolving with nearly simultaneous advances in surgical techniques and adjunctive therapies, respiratory care, intensive care technology and monitoring, pharmacologic research and development, and computing and electronics. The focus of care has now shifted toward reducing morbidity and improving "quality of life" while the survival of infants and children with congenital heart defects, including those with univentricular hearts has dramatically improved during the last three decades. Despite these advances, there remains a predictable fall in cardiac output after cardiopulmonary bypass. This article focuses on early identification and aggressive treatment of the low cardiac output syndrome peculiar to these patients. The authors also briefly review the recent advances in the treatment of pulmonary hypertension, mechanical support, and neurologic surveillance after cardiac surgery.

Novel therapeutic approaches in sickle cell disease

In this update, selected clinical features of sickle cell disease and their management are reviewed. In addition, the current status of interventions that have curative potential for sickle cell disease is discussed, with particular attention focused on indications, methodology, recent results, and challenges to wider clinical application. In Section I, Dr. Nienhuis describes recent improvements in vector technology, safety, and replacement gene expression that are creating the potential for clinical application of this technology. In Section II, Dr. Vichinsky reviews our current understanding of the pathophysiology and treatment of pulmonary injury in sickle cell disease. The acute and chronic pulmonary complications of sickle cell disease, modulators and predictors of severity, and conventional and novel treatment of these complications are discussed. In Section III, Dr. Walters reviews the current status of hematopoietic cell transplantation for sickle cell disease. Newer efforts to expand its availability by identifying alternate sources of stem cells and by reducing the toxicity of transplantation are discussed.

Recent advances in the treatment of pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension is a debilitating life-threatening disease of all ages. The long-term prognosis can be dismal despite maximal medical therapy. There have been significant advances in our understanding of the pathobiology and genetics of this disease, and novel pharmacological approaches appear to offer promising alternatives to conventional therapy. Anesthesiologists have been instrumental in the development and widespread clinical introduction of inhaled nitric oxide. Unfortunately, despite early optimism, inhaled nitric oxide has several significant limitations related to its cost, toxicity, required complex technology, and occasional therapeutic failure. Therefore, there is a need for an effective alternative pulmonary vasodilator. The early diagnosis and treatment of pulmonary hypertension are crucial if improvements are to be realized. This review will present recent work in this field in an attempt to increase anesthesiologists' awareness of potential new treatment options.

RECENT FINDINGS

Emerging data concerning the genetics of certain pulmonary hypertension variants have provided insight into the pathobiology of this disease and may lead to advances in the early detection or new treatment options. New pharmacological approaches include drugs such as nitric oxide donors, phosphodiesterase inhibitors, endothelin antagonists, and prostacyclin analogues. Attention has also been focused on the use of combinations of drugs of different classes.

SUMMARY

The clinical outcome of pulmonary hypertension is dependent upon early detection and therapy. Increased awareness of current therapeutic options will facilitate earlier effective treatment.