A model of respiratory syncytial virus (RSV) infection of infants in newborn lambs

Many animal models have been established for respiratory syncytial virus (RSV) infection of infants with the purpose of studying the pathogenesis, immunological response, and pharmaceutical testing and the objective of finding novel therapies and preventive measures. This review centers on a neonatal lamb model of RSV infection that has similarities to RSV infection of infants. It includes a comprehensive description of anatomical and immunological similarities between ovine and human lungs along with comparison of pulmonary changes and immune responses with RSV infection. These features make the newborn lamb an effective model for investigating key aspects of RSV infection in infants. The importance of RSV lamb model application in preclinical therapeutic trials and current updates on new studies with the RSV-infected neonatal lamb are also highlighted.

Minimal invasive lung support via umbilical vein with a double-lumen cannula in a neonatal lamb model: a proof of principle

PURPOSE

Acute respiratory distress syndrome, with the need for invasive mechanical ventilation (MV) remains a major cause of neonatal mortality and morbidity. Although venovenous extracorporeal lung support (VV-ECLS) has become a standard of care procedure in neonatal patients with acute pulmonary failure there are no reports regarding the use of a double-lumen cannula for extracorporeal minimal invasive lung support via the umbilical vein.

METHODS

A neonatal lamb model was used (n = 3). Umbilical vein was cannulated with a double-lumen catheter allowing venovenous extracorporeal gas exchange. Cannula was positioned with its tip in the right atrium. VV-ECLS was started and ventilation was stopped. Providing oxygenation and CO2 removal solely through VV-ECLS hemodynamics, blood gases were measured.

RESULTS

Total VV-ECLS without MV was applied to all three neonatal lambs. Time on venovenous ECLS was 60, 120 and 120 min. Initial pCO2 was 60, 56 and 65 mmHg compared to 31, 32 and 32 mmHg at the end of VV-ECLS. Initial pO2 was 30, 27 and 26 mmHg compared to 22, 19 and 23 mmHg. Initial lactate was 5, 10 and 3.7 mmol/l compared to 13.3, 12.6 and 11.3 mmol/l at the end of VV-ECLS. MAP at baseline was 51, 52 and 65 mmHg compared to 36, 38 and 41 mmHg at the end of VV-ECLS. In all three lambs inotropes were admitted to maintain MAD >35 mmHg.

CONCLUSION

Even without mechanical ventilation we were able to sufficiently remove pCO2 with our new minimal invasive VV-ECLS using a double-lumen catheter via the umbilical vein, supporting the idea of a lung protective strategy in neonatal acute respiratory failure. pO2 was measured 22, 19 and 23 mmHg, respectively, at the end of VV-ECLS, at least partially caused by recirculation phenomenon, which could possibly be improved by different cannula design. Inotropic support was necessary during VV-ECLS to achieve targeted MAD > 35 mmHg. While technically feasible, this new approach might allow further research in the field of extracorporeal lung support and therefore will follow the concept of a lung protective strategy in acute neonatal respiratory failure.