Pharmacodynamic considerations in the treatment of pulmonary hypertension in infants: challenges and future perspectives

Sildenafil protects against pulmonary hypertension induced by hypoxia in neonatal rats via activation of PPARγ‑mediated downregulation of TRPC

Persistent pulmonary hypertension of the newborn (PPHN) is a common pulmonary vascular disease during the neonatal period, and it is associated with a high clinical mortality rate and a poor prognosis. At present, the treatment of PPHN is based mainly on inhaled nitric oxide (iNO), high‑frequency ventilation, and pulmonary vasodilators. Sildenafil has gradually begun to be used in recent years for the treatment of PPHN and has exhibited some success; however, its detailed mechanism of action requires further elucidation. An animal model of neonatal pulmonary hypertension (neonatal rats, 48 h after birth, 10% O2, 14 days) as well as a cell model [human pulmonary artery smooth muscle cells (PASMCs), 4% O2, 60 h] were established. The effects of sildenafil on pulmonary hypertension in neonatal rats were evaluated by hematoxylin and eosin staining, immunofluorescence analysis, western blotting and PCR, and the changes in peroxisome proliferator‑activated receptor γ (PPARγ), transient receptor potential canonical (TRPC)1, TRPC6 and Ki67 expression levels were detected under hypoxic conditions. The results revealed that sildenafil reversed the increases in the right ventricular mean pressure and right ventricular hypertrophy index induced by hypoxia, and attenuated pulmonary arterial remodeling as well as PASMC proliferation. The inhibitory effects of sildenafil on TRPC expression and PASMC proliferation were attenuated by GW9662 and PPARγ small interfering RNA. In conclusion, sildenafil protects against hypoxia‑induced pulmonary hypertension and right ventricular hypertrophy in neonatal rats by upregulating PPARγ expression and downregulating TRPC1 and TRPC6 expression.

Perinatal stabilisation of infants born with congenital diaphragmatic hernia: a review of current concepts

Congenital diaphragmatic hernia (CDH) is associated with high mortality rates and significant pulmonary morbidity, mainly due to disrupted lung development related to herniation of abdominal organs into the chest. Pulmonary hypertension is a major contributor to both mortality and morbidity, however, treatment modalities are limited. Novel prenatal and postnatal interventions, such as fetal surgery and medical treatments, are currently under investigation. Until now, the perinatal stabilisation period immediately after birth has been relatively overlooked, although optimising support in these early stages may be vital in improving outcomes. Moreover, physiological parameters obtained from the perinatal stabilisation period could serve as early predictors of adverse outcomes, thereby facilitating both prevention and early treatment of these conditions. In this review, we focus on the perinatal stabilisation period by discussing the current delivery room guidelines in infants born with CDH, the physiological changes occurring during the fetal-to-neonatal transition in CDH, novel delivery room strategies and early predictors of adverse outcomes. The combination of improvements in the perinatal stabilisation period and early prediction of adverse outcomes may mitigate the need for specific postnatal management strategies.

Supporting the use of sildenafil infusions in paediatric and neonatal intensive care - A compatibility study

OBJECTIVE

Intravenous (IV) sildenafil, a phosphodiesterase type 5 inhibitor, is increasingly being used for the treatment of pulmonary hypertension (PH) in the paediatric population. Sildenafil (Revatio®) is approved for the treatment of pH in adults where it is administered as a bolus injection. However, in paediatrics it is used off-label and administered by continuous IV infusion. In the critically unwell child, limited IV access necessitates the administration of multiple IV infusions through a single IV lumen. The absence of compatibility data between sildenafil and other IV medications commonly used in this context necessitates the use of a dedicated IV line for sildenafil. The overall aim of this study was to establish the physical and chemical compatibility of sildenafil with commonly administered infusions in the paediatric and neonatal intensive care setting.

DESIGN

This study evaluated the chemical and physical compatibility of binary and multiple combinations (n = 42) of sildenafil with adrenaline, noradrenaline, milrinone, vasopressin and heparin. These were tested using three diluents (NaCl 0.9%w/v, Glucose 5%w/v, and Glucose 10%w/v) and two environmental conditions (room temperature and 37 °C) frequently encountered in paediatric or neonatal intensive care units. Prior to drug combination analysis, HPLC methods were developed and optimised to allow for the quantification of drugs in accordance with current pharmaceutical guidance. Binary and multiple drug mixtures of sildenafil were examined for physical and chemical compatibility to establish compatibility.

MEASUREMENTS AND MAIN RESULTS

Of the drug combinations not containing heparin, all were deemed compatible with the exception of the five drug mix of Sildenafil 800 μg/mL, Milrinone 200 μg/mL, Vasopressin 0.4Units/mL, Noradrenaline 60 μg/mL, Adrenaline 60 μg/mL at 37 °C, in 10%w/v glucose. All binary or multi drug combinations containing heparin were deemed incompatible.

CONCLUSIONS

This research provides support and information to clinicians looking to co-administer sildenafil with other IV medicines thus removing the requirement to subject their patients to multiple intravenous cannula insertion points where IV access is restricted.

ARTICLE TWEET

New evidence to support administration of sildenafil infusions in #PedsICU and #nicu- collaboration between @RCSIPharBioMol@FionaSOBrien1 and @OLCHCrumlin @RCSI_Irl @MoninneHowlett #CHI.

Transport on extracorporeal membrane oxygenation for congenital diaphragmatic hernia: A unique center experience

BACKGROUND

Support on Extracorporeal oxygenation membrane (ECMO) represents the last therapeutic option in the management of respiratory failure and pulmonary hypertension refractory to treatment in patients with congenital diaphragmatic hernia (CDH).

AIM

The objective of this work was to present our experience of all the cases of CDH that we have transported on ECMO.

MATERIAL AND METHODS

Medical records of patients, national and international, with CDH transported by our service on ECMO from 1997 to 2018 were reviewed.

RESULTS

During 22 years, we performed 40 ECMO transports of newborns with CDH, 39 primary and one secondary. In 10% (4/40) we transferred patients from their primary hospital after the implantation of cannulae and commencement of ECMO to another center abroad owing to the lack of beds in our unit. Twenty (50%) of the transports were from a foreign country. Median transport distance was 560 (428-1381) km and the median transport time was 4.5 (4.2-6.3) h. The mode of transport was ground ambulance in 20%, helicopter in 10%, fixed wing aircraft in 62.5% and ground ambulance in Freight aircraft in 7.5%. In 40% of the transports, 20 complications occurred. In one of every four transports with complications, more than one event occurred. Most frequent complication was loss of tidal volumes (35%) and in 30% of the complications another patient related event was recorded. Equipment failure occurred in 20%, and climate problems and transport vehicle problems in 15%. No deaths occurred during transport. Venoarterial ECMO was used in 39 of the 40 cases. Survival to discharge was 87% for the entire period and long-term survival was 77%.

CONCLUSIONS

Long and short distance interhospital transports of CDH patients on ECMO can be performed safely. Despite occurrence of adverse events, the risk of mortality is very low. The personnel involved must be highly competent in intensive care, physiology and physics of ECMO, cannulation, intensive care transport and air transport medicine. They must also be trained to recognize risk factors in these patients.

LEVEL OF EVIDENCE

III Retrospective cohort study.

Non-maturational covariates for dynamic systems pharmacology models in neonates, infants, and children: Filling the gaps beyond developmental pharmacology

Pharmacokinetics and -dynamics show important changes throughout childhood. Studies on the different maturational processes that influence developmental pharmacology have been used to create population PK/PD models that can yield individualized pediatric drug dosages. These models were subsequently translated to semi-physiologically or physiology-based PK (PBPK) models that support predictions in pediatric patient cohorts and other special populations. Although these translational efforts are crucial, these models should be further improved towards individual patient predictions by including knowledge on non-maturational covariates. These efforts are needed to ultimately get to systems pharmacology models for children. These models take developmental changes relating to the pediatric dynamical system into account but also other aspects that may be of importance such as abnormal body composition, pharmacogenetics, critical illness and inflammatory status.