Theresa R. Grover

Cinaciguat, a soluble guanylate cyclase activator, augments cGMP after oxidative stress and causes pulmonary vasodilation in neonatal pulmonary hypertension

Although inhaled NO (iNO) therapy is often effective in treating infants with persistent pulmonary hypertension of the newborn (PPHN), up to 40% of patients fail to respond, which may be partly due to abnormal expression and function of soluble guanylate cyclase (sGC). To determine whether altered sGC expression or activity due to oxidized sGC contributes to high pulmonary vascular resistance (PVR) and poor NO responsiveness, we studied the effects of cinaciguat (BAY 58-2667), an sGC activator, on pulmonary artery smooth muscle cells (PASMC) from normal fetal sheep and sheep exposed to chronic intrauterine pulmonary hypertension (i.e., PPHN). We found increased sGC α(1)- and β(1)-subunit protein expression but lower basal cGMP levels in PPHN PASMC compared with normal PASMC. To determine the effects of cinaciguat and NO after sGC oxidation in vitro, we measured cGMP production by normal and PPHN PASMC treated with cinaciguat and the NO donor, sodium nitroprusside (SNP), before and after exposure to 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, an sGC oxidizer), hyperoxia (fraction of inspired oxygen 0.50), or hydrogen peroxide (H(2)O(2)). After treatment with ODQ, SNP-induced cGMP generation was markedly reduced but the effects of cinaciguat were increased by 14- and 64-fold in PPHN fetal PASMC, respectively (P < 0.01 vs. controls). Hyperoxia or H(2)O(2) enhanced cGMP production by cinaciguat but not SNP in PASMC. To determine the hemodynamic effects of cinaciguat in vivo, we compared serial responses to cinaciguat and ACh in fetal lambs after ductus arteriosus ligation. In contrast with the impaired vasodilator response to ACh, cinaciguat-induced pulmonary vasodilation was significantly increased. After birth, cinaciguat caused a significantly greater fall in PVR than either 100% oxygen, iNO, or ACh. We conclude that cinaciguat causes more potent pulmonary vasodilation than iNO in experimental PPHN. We speculate that increased NO-insensitive sGC may contribute to the pathogenesis of PPHN, and cinaciguat may provide a novel treatment of severe pulmonary hypertension.

Pulmonary vascular effects of serotonin and selective serotonin reuptake inhibitors in the late-gestation ovine fetus

Maternal use of selective serotonin (5-HT) reuptake inhibitors (SSRIs) is associated with an increased risk for persistent pulmonary hypertension of the newborn (PPHN), but little is known about 5-HT signaling in the developing lung. We hypothesize that 5-HT plays a key role in maintaining high pulmonary vascular resistance (PVR) in the fetus and that fetal exposure to SSRIs increases 5-HT activity and causes pulmonary hypertension. We studied the hemodynamic effects of 5-HT, 5-HT receptor antagonists, and SSRIs in chronically prepared fetal sheep. Brief infusions of 5-HT (3-20 μg) increased PVR in a dose-related fashion. Ketanserin, a 5-HT 2A receptor antagonist, caused pulmonary vasodilation and inhibited 5-HT-induced pulmonary vasoconstriction. In contrast, intrapulmonary infusions of GR127945 and SB206553, 5-HT 1B and 5-HT 2B receptor antagonists, respectively, had no effect on basal PVR or 5-HT-induced vasoconstriction. Pretreatment with fasudil, a Rho kinase inhibitor, blunted the effects of 5-HT infusion. Brief infusions of the SSRIs, sertraline and fluoxetine, caused potent and sustained elevations of PVR, which was sustained for over 60 min after the infusion. SSRI-induced pulmonary vasoconstriction was reversed by infusion of ketanserin and did not affect the acute vasodilator effects of acetylcholine. We conclude that 5-HT causes pulmonary vasoconstriction, contributes to maintenance of high PVR in the normal fetus through stimulation of 5-HT 2A receptors and Rho kinase activation, and mediates the hypertensive effects of SSRIs. We speculate that prolonged exposure to SSRIs can induce PPHN through direct effects on the fetal pulmonary circulation.

Cinaciguat, a soluble guanylate cyclase activator, causes potent and sustained pulmonary vasodilation in the ovine fetus

Impaired nitric oxide-cGMP signaling contributes to severe pulmonary hypertension after birth, which may in part be due to decreased soluble guanylate cyclase (sGC) activity. Cinaciguat (BAY 58-2667) is a novel sGC activator that causes vasodilation, even in the presence of oxidized heme or heme-free sGC, but its hemodynamic effects have not been studied in the perinatal lung. We performed surgery on eight fetal (126 +/- 2 days gestation) lambs (full term = 147 days) and placed catheters in the main pulmonary artery, aorta, and left atrium to measure pressures. An ultrasonic flow transducer was placed on the left pulmonary artery to measure blood flow, and a catheter was placed in the left pulmonary artery for drug infusion. Cinaciguat (0.1-100 microg over 10 min) caused dose-related increases in pulmonary blood flow greater than fourfold above baseline and reduced pulmonary vascular resistance by 80%. Treatment with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an sGC-oxidizing inhibitor, enhanced cinaciguat-induced pulmonary vasodilation by >120%. The pulmonary vasodilator effect of cinaciguat was prolonged, decreasing pulmonary vascular resistance for >1.5 h after brief infusion. In vitro stimulation of ovine fetal pulmonary artery smooth muscle cells with cinaciguat after ODQ treatment resulted in a 14-fold increase in cGMP compared with non-ODQ-treated cells. We conclude that cinaciguat causes potent and sustained fetal pulmonary vasodilation that is augmented in the presence of oxidized sGC and speculate that cinaciguat may have therapeutic potential for severe neonatal pulmonary hypertension.

Case report: infantile hemangioendothelioma.

During a routine physical exam, an 18-day-old male infant was noted to have persistent abdominal distention and prominent vascular markings over his abdominal wall. Laboratory studies were significant for an elevated &agr;-fetoprotein level of 7051 ng/ml and mild anemia. Abdominal ultrasound and CT scan demonstrated a large, heterogeneous mass in the lateral segment of the left lobe of the liver. Although the patient did not have congestive heart failure or coagulopathy, surgical resection was performed to rule out malignancy. Histopathologic examination revealed a type I infantile hemangioendothelioma. This case report reviews the presentation and treatment of infantile hemangioendotheliomas and the differential diagnosis of neonatal hepatic neoplasms.

Fasudil inhibits the Myogenic Response in the Fetal Pulmonary Circulation

In addition to high pulmonary vascular resistance (PVR) and low pulmonary blood flow, the fetal pulmonary circulation is characterized by mechanisms that oppose vasodilation. Past work suggests that high myogenic tone contributes to high PVR and may contribute to autoregulation of blood flow in the fetal lung. Rho-kinase (ROCK) can mediate the myogenic response in the adult systemic circulation, but whether high ROCK activity contributes to the myogenic response and modulates time-dependent vasodilation in the developing lung circulation are unknown. We studied the effects of fasudil, a ROCK inhibitor, on the hemodynamic response during acute compression of the ductus arteriosus (DA) in chronically prepared, late-gestation fetal sheep. Acute DA compression simultaneously induces two opposing responses: 1) blood flow-induced vasodilation through increased shear stress that is mediated by NO release and 2) stretch-induced vasoconstriction (i.e., the myogenic response). The myogenic response was assessed during acute DA compression after treatment with N(omega)-nitro-L-arginine, an inhibitor of nitric oxide synthase, to block flow-induced vasodilation and unmask the myogenic response. Intrapulmonary fasudil infusion (100 microg over 10 min) did not enhance flow-induced vasodilation during brief DA compression but reduced the myogenic response by 90% (P<0.05). During prolonged DA compression, fasudil prevented the time-dependent decline in left pulmonary artery blood flow at 2 h (183+/-29 vs. 110+/-11 ml/min with and without fasudil, respectively; P<0.001). We conclude that high ROCK activity opposes pulmonary vasodilation in utero and that the myogenic response maintains high PVR in the normal fetal lung through ROCK activation.

Vascular endothelial growth factor causes pulmonary vasodilation through activation of the phosphatidylinositol-3-kinase-nitric oxide pathway in the late-gestation ovine fetus.

Vascular endothelial growth factor (VEGF) causes vasodilation in adult models of peripheral vascular disease and myocardial ischemia through the acute release of nitric oxide (NO). However, the hemodynamic effects of VEGF and its effects on NO production have not been studied in the developing lung circulation. We hypothesized that VEGF causes fetal pulmonary vasodilation, and that its actions are mediated through the release of endogenous NO. We performed surgery in 16 fetal lambs (125–135 d gestation; term = 147 d), and placed catheters in the main pulmonary artery, aorta, and left atrium to measure pressures. An ultrasonic flow transducer was placed on the left pulmonary artery (LPA) to measure blood flow, and a catheter was placed in the LPA for local drug infusion. Pulmonary vascular resistance in the left lung was calculated as pulmonary artery pressure minus left atrial pressure divided by LPA flow. Fetal lambs were treated with brief infusions of recombinant human VEGF (dose, 0.5–2.0 μg) into the LPA. Recombinant human VEGF infusions acutely increased LPA flow by up to 3-fold (p < 0.02) and decreased pulmonary vascular resistance by 65% (p < 0.05) in a dose-related fashion, without affecting aortic pressure or heart rate. To determine the mechanism of VEGF-induced vasodilation, we studied the effects of nitro-l-arginine, an NO synthase inhibitor, and LY294002, a phosphatidylinositol-3-kinase inhibitor, on the response to VEGF. We found that pretreatment with either nitro-l-arginine or LY294002 completely inhibited the vasodilator response to recombinant human VEGF (p < 0.005). These findings suggest that recombinant human VEGF causes fetal pulmonary vasodilation, and that this response is likely mediated by the release of NO through activation of phosphatidylinositol-3-kinase.

SLUG Bug: Quality Improvement With Orchestrated Testing Leads to NICU CLABSI Reduction.

OBJECTIVE: Reduce central line–associated bloodstream infection (CLABSI) rates 15% over 12 months in children’s hospital NICUs. Use orchestrated testing as an approach to identify important CLABSI prevention practices. METHODS: Literature review, expert opinion, and benchmarking were used to develop clinical practice recommendations for central line care. Four existing CLABSI prevention strategies (tubing change technique, hub care monitoring, central venous catheter access limitation, and central venous catheter removal monitoring) were identified for study. We compared the change in CLABSI rates from baseline throughout the study period in 17 participating centers. Using orchestrated testing, centers were then placed into 1 of 8 test groups to identify which prevention practices had the greatest impact on CLABSI reduction. RESULTS: CLABSI rates decreased by 19.28% from 1.333 to 1.076 per 1000 line-days. Six of the 8 test groups and 14 of the 17 centers had decreased infection rates; 16 of the 17 centers achieved >75% compliance with process measures. Hub scrub compliance monitoring, when used in combination with sterile tubing change, decreased CLABSI rates by 1.25 per 1000 line-days. CONCLUSIONS: This multicenter improvement collaborative achieved a decrease in CLABSI rates. Orchestrated testing identified infection prevention practices that contribute to reductions in infection rates. Sterile tubing change in combination with hub scrub compliance monitoring should be considered in CLABSI reduction efforts.

Therapeutic interventions and short-term outcomes for infants with severe bronchopulmonary dysplasia born at <32 weeks' gestation.

Objective:To characterize the treatments and short-term outcomes in infants with severe bronchopulmonary dysplasia (sBPD) referred to regional neonatal intensive care units.Study Design:Infants born <32 weeks’ gestation with sBPD were identified using the Children’s Hospital Neonatal Database. Descriptive outcomes are reported.Result:A total of 867 patients were eligible. On average, infants were born at 26 weeks’ gestation and referred 43 days after birth. Infants frequently experienced lung injury (pneumonia: 24.1%; air leak: 9%) and received systemic corticosteroids (61%) and mechanical ventilation (median duration 37 days). Although 91% survived to discharge, the mean post-menstrual age was 47 weeks. Ongoing care such as supplemental oxygen (66%) and tracheostomy (5%) were frequently needed.Conclusion:Referred infants with sBPD sustain multiple insults to lung function and development. Because affected infants have no proven, safe or efficacious therapy and endure an exceptional burden of care even after referral, urgent work is required to observe and improve their outcomes.

Interdisciplinary teamwork and the power of a quality improvement collaborative in tertiary neonatal intensive care units.

Significant gaps in healthcare quality and outcomes can be reduced via quality improvement collaboratives (QICs), which improve care by leveraging data and experience from multiple organizations. The Childrens Hospital Neonatal Consortium Collaborative Initiatives for Quality Improvement team developed an infrastructure for neonatal QICs. We describe the structure and components of an effective multi-institutional neonatal QIC that implemented the “SLUG Bug” project designed to reduce central line-associated bloodstream infections (CLABSIs). The operational infrastructure of SLUG Bug involved 17 tertiary care neonatal intensive care units with a goal to reduce CLABSI in high-risk neonates. Clinical Practice Recommendations were produced, and the Institute of Healthcare Improvement Breakthrough Series provided the framework for the collaborative. Process measures studied the effectiveness of the collaborative structure. CLABSI rates decreased by 20% during a 12-month study period. Compliance bundle reporting exceeded 80%. A QIC score of 2.5 or more (“improvement”) was achieved by 94% of centers and a score 4 or more (“significant improvement”) was achieved by 35%. Frequent interactive project meetings, well-defined project metrics, continual shared learning opportunities, and individual team coaching were key QIC success components. Through a coordinated approach and committed leadership, QICs can effectively implement change and improve the care of neonates with complex diagnoses and rare diseases.

Predicting death or extended length of stay in infants with congenital diaphragmatic hernia

Objective:To predict mortality or length of stay (LOS) >109 days (90th percentile) among infants with congenital diaphragmatic hernia (CDH).Study Design:We conducted a retrospective analysis using the Childrens Hospital Neonatal Database during 2010 to 2014. Infants born >34 weeks gestation with CDH admitted at 22 participating regional neonatal intensive care units were included; patients who were repaired or were at home before admission were excluded. The primary outcome was death before discharge or LOS >109 days. Factors associated with this outcome were used to develop a multivariable equation using 80% of the cohort. Validation was performed in the remaining 20% of infants.Results:The median gestation and age at referral in this cohort (n=677) were 38 weeks and 6 h, respectively. The primary outcome occurred in 242 (35.7%) infants, and was distributed between mortality (n=180, 27%) and LOS >109 days (n=66, 10%). Regression analyses showed that small for gestational age (odds ratio (OR) 2.5, P=0.008), presence of major birth anomalies (OR 5.9, P<0.0001), 5- min Apgar score ⩽3 (OR 7.0, P=0.0002), gradient of acidosis at the time of referral (P<0.001), the receipt of extracorporeal support (OR 8.4, P<0.0001) and bloodstream infections (OR 2.2, P=0.004) were independently associated with death or LOS >109 days. This model performed well in the validation cohort (area under curve (AUC)=0.856, goodness-of-fit (GF) χ2, P=0.16) and acted similarly even after omitting extracorporeal support (AUC=0.82, GF χ2, P=0.05).Conclusions:Six variables predicted death or LOS ⩾109 days in this large, contemporary cohort with CDH. These results can assist in risk adjustment for comparative benchmarking and for counseling affected families.