An Unsettled Promise: The Newborn Piglet Model of Neonatal Acute Respiratory Distress Syndrome (NARDS). Physiologic Data and Systematic Review

Lung Ultrasound Induction of Pulmonary Capillary Hemorrhage in Neonatal Swine

This study investigated induction of pulmonary capillary hemorrhage (PCH) in neonatal pigs (piglets) using three different machines: a GE Venue R1 point-of-care system with C1-5 and L4-12t probes, a GE Vivid 7 Dimension with a 7L probe and a SuperSonic Imagine machine with an SL15-4 probe and shear wave elastography (SWE). Female piglets were anesthetized, and each was mounted vertically in a warm bath for scanning at two or three intercostal spaces. After aiming at an innocuous output, the power was raised for a test exposure. Hydrophone measurements were used to calculate in situ values of mechanical index (MIIS). Inflated lungs were removed and scored for PCH area. For the C1-5 probe at 50% and 100% acoustical output (AO), a PCH threshold of 0.53 MIIS was obtained by linear regression (r2 = 0.42). The L4-12t probe did not induce PCH, but the 7L probe induced zones of PCH in the scan planes. The Venue R1 automated B-line tool applied with the C1-5 probe did not detect PCH induced by the C1-5 probe as B-line counts. However, when PCH induced by C1-5 and 7L exposures were subsequently scanned with the L4-12t probe using the automated tool, B-lines were counted in association with the PCH. The SWE induced PCH at push-pulse positions for 3, 30 and 300 s of SWE with PCH accumulating at 0.33 mm2/s and an exponential rise to a maximum of 18.4 mm2 (r2 = 0.61). This study demonstrated the induction of PCH by LUS of piglets, and supports the safety recommendation for use of MIs <0.4 in neonatal LUS.

Changes in the live birth profile in Henan, China: A hospital registry-based study

BACKGROUND

Preterm complications and neonatal asphyxia are the leading causes of death in those under 5 years of age. However, little information exists for the province of Henan, China. The purpose of this study was to explore changes in the live birth profile in a provincial hospital over the past 32 years in Henan, China.

METHODS

A retrospective analysis was conducted to reveal the characteristics of live neonates from 1987 to 2018.

RESULTS

There were 118 253 live births during the period, including 19 798 (16.74%) preterm births. The neonatal death rate was 6.45‰, and the top risk factor was preterm birth complications and birth asphyxia. Before 1998, neonatal death occurred primarily among term infants. Between 1999 and 2018, preterm infants, especially extreme and very preterm infants with very low birthweight, constituted more than half of all mortalities, and the preterm birth rate increased from 5.94% in 1999 to 16.69% in 2018. The risk factors associated with preterm birth were being male (aOR = 1.18, P < 0.001), advanced maternal age (>35 years old; aOR = 1.08, P = 0.008), gravidity ≥2 (aOR = 1.15, P < 0.001), parity ≥2 (aOR = 1.50, P < 0.001), placenta previa (aOR = 7.41, P < 0.001), twin or multiple births (aOR = 10.63, P < 0.001), hypertension (aOR = 2.08, P < 0.001), and rupture of membrane (aOR = 5.03, P < 0.001).

CONCLUSIONS

The preterm birth rate has increased over the past 32 years from 4.98% to 16.69% in a provincial hospital in China. Preterm birth was the leading reason for neonatal death, and birth asphyxia was the major risk factor for death in term infants.

Nebulization of High-Dose Poractant Alfa in Newborn Piglets on Nasal Continuous Positive Airway Pressure Yields Therapeutic Lung Doses of Phospholipids

OBJECTIVE

It is not known how much surfactant must be nebulized to reach a lung dose of phospholipids equivalent to that obtained by the instillation of 200 mg/kg of surfactant. We aimed to assess the feasibility of nebulizing a high-dose of poractant alfa with the eFlow-Neos investigational vibrating-membrane nebulizer in newborn piglets on nasal continuous positive airway pressure (nCPAP) and to determine whether this intervention would yield therapeutic lung doses of phospholipids.

STUDY DESIGN

Twelve 1-day-old piglets on nCPAP received 600 mg/kg of poractant alfa admixed with technetium-99m via nebulization. Six piglets receiving 200 mg/kg of instilled synthetic surfactant served as controls. Lung deposition (percentage of the nominal dose) was determined by gamma scintigraphy, and the phospholipids' lung dose was calculated.

RESULTS

The lung dose of phospholipids (mean ± standard deviation [SD]) was 138 ± 96 mg/kg with nebulization, and 172 ± 24 mg/kg with instillation (p = 0.42). Nebulization took 58 ± 12 minutes. The arterial partial pressure of carbon dioxide increased from 6.7 ± 1.1 to 7.2 ± 1.1 kPa during nebulization (p = 0.04). Cerebral oximetry remained stable, and there was no hemodynamic instability.

CONCLUSION

Nebulization was well tolerated, and the mean lung dose of phospholipids was above 100 mg/kg, that is, not different from the instillation group. These experimental findings suggest that it may be feasible to reach therapeutic lung doses of phospholipids by surfactant nebulization during nCPAP.

KEY POINTS

· It is not known if effective lung doses of surfactant can be delivered by nebulization.. · Nebulization of high-dose surfactant in newborn piglets on nCPAP was well tolerated.. · A high-dose of nebulized poractant alfa yielded therapeutic lung doses of phospholipids..

Ultrasound-guided percutaneous central venous access in a neonatal porcine model

Percutaneous catheterization is currently utilized for central venous access in adult and adolescent porcine models; however, neonatal models require a cut down to gain venous access. This approach requires general anesthesia and can result in systemic inflammation, which can confound studies investigating other inflammatory triggers. Here we present the first successful series of percutaneous, ultrasound-guided, durable central venous access in newborn piglets weighing 1 kg with a novel method of tunneling the catheter subcutaneously using a needle. Catheters (3-5 Fr, single- or double-lumen) were successfully placed in the right jugular vein of eight piglets weighing 1.3 ± 0.4 kg (mean ± standard deviation) with an average duration of catheter patency of 4.5 ± 2.1 days. There were no adverse events from catheter placement, though one catheter was inadvertently removed. This technique is a safe, minimally invasive method for obtaining secure central venous access in a neonatal porcine model.

Surfactant therapies for pediatric and neonatal ARDS: ESPNIC expert consensus opinion for future research steps

Pediatric (PARDS) and neonatal (NARDS) acute respiratory distress syndrome have different age-specific characteristics and definitions. Trials on surfactant for ARDS in children and neonates have been performed well before the PARDS and NARDS definitions and yielded conflicting results. This is mainly due to heterogeneity in study design reflecting historic lack of pathobiology knowledge. We reviewed the available clinical and preclinical data to create an expert consensus aiming to inform future research steps and advance the knowledge in this area. Eight trials investigated the use of surfactant for ARDS in children and ten in neonates, respectively. There were improvements in oxygenation (7/8 trials in children, 7/10 in neonates) and mortality (3/8 trials in children, 1/10 in neonates) improved. Trials were heterogeneous for patients' characteristics, surfactant type and administration strategy. Key pathobiological concepts were missed in study design. Consensus with strong agreement was reached on four statements: 1. There are sufficient preclinical and clinical data to support targeted research on surfactant therapies for PARDS and NARDS. Studies should be performed according to the currently available definitions and considering recent pathobiology knowledge. 2. PARDS and NARDS should be considered as syndromes and should be pre-clinically studied according to key characteristics, such as direct or indirect (primary or secondary) nature, clinical severity, infectious or non-infectious origin or patients' age. 3. Explanatory should be preferred over pragmatic design for future trials on PARDS and NARDS. 4. Different clinical outcomes need to be chosen for PARDS and NARDS, according to the trial phase and design, trigger type, severity class and/or surfactant treatment policy. We advocate for further well-designed preclinical and clinical studies to investigate the use of surfactant for PARDS and NARDS following these principles.

The Neonatal and Juvenile Pig in Pediatric Drug Discovery and Development

Pharmacotherapy in pediatric patients is challenging in view of the maturation of organ systems and processes that affect pharmacokinetics and pharmacodynamics. Especially for the youngest age groups and for pediatric-only indications, neonatal and juvenile animal models can be useful to assess drug safety and to better understand the mechanisms of diseases or conditions. In this respect, the use of neonatal and juvenile pigs in the field of pediatric drug discovery and development is promising, although still limited at this point. This review summarizes the comparative postnatal development of pigs and humans and discusses the advantages of the juvenile pig in view of developmental pharmacology, pediatric diseases, drug discovery and drug safety testing. Furthermore, limitations and unexplored aspects of this large animal model are covered. At this point in time, the potential of the neonatal and juvenile pig as nonclinical safety models for pediatric drug development is underexplored.

Organic vs. Inorganic Tracheobronchial Airway Foreign Body Aspiration: Does Type/Duration Matter?

OBJECTIVE

We sought to determine the time course of clinical and histologic differences between aspirated inorganic and organic foreign bodies.

STUDY DESIGN

In-vivo.

METHODS

Twenty Sinclair miniature swine (Sus scrofa domesticus) were divided into two groups-inorganic or organic foreign bodies. Either an organic (peanut) or an inorganic (Lego) foreign body was placed within a bronchus and left for 3, 5, 7, 14 or 21 days. The airway was reassessed at the predetermined endpoint at which time endoscopic, gross, and histopathological findings were documented. Specimens were scored with a pathologic scoring system to assess injury severity from the foreign body.

RESULTS

Foreign bodies were successfully placed in all 20 swine. Two animals required early euthanasia due to respiratory compromise. The foreign body was identified grossly in eight (40%) animals. An additional three (15%) had microscopic evidence suggestive of a previous foreign body of an undetermined duration. There was no difference in injury severity between organic and inorganic foreign bodies. The 3-day group had injuries limited to the bronchial lining, whereas the longer duration groups had bronchial and adjacent lung parenchymal involvement. There was no difference in injury severity between days 5 and 21.

CONCLUSIONS

Airway foreign bodies initially cause bronchial damage. After 5 days, the foreign body causes lung parenchymal changes. There was no difference in airway lesion severity between organic and inorganic foreign bodies.

LEVEL OF EVIDENCE

N/A Laryngoscope, 131:490-495, 2021.