Validating a bovine model for lung ultrasound of bronchiolitis

Abstract

Purpose Bronchiolitis is a very common acute lung disease in infants caused commonly by respiratory syncytial virus (RSV). Point-of-care lung ultrasound is increasingly used in clinical care but proof that ultrasound reflects histological disease is lacking. Bovine calves are a good model for RSV bronchiolitis. We answered the following two questions: (1) does point-of-care lung ultrasound reflect lung pathology at the histological level in a bovine calf model of bronchiolitis? and (2) are point-of-care lung ultrasound images in human infants similar to those obtained in calves? Methods We experimentally infected 24 five to six-week-old bovine calves with RSV and compared six window lung ultrasound with lung histology10 days after inoculation. The calves were treated with antivirals and antipyretics leading to variable severity of illness. We used canonical discriminant analysis to determine if abnormal lung ultrasound findings reflected different histological findings. We compared the ultrasounds obtained from the calves with ultrasounds obtained from 10 human infants who were diagnosed clinically with bronchiolitis. Results Canonical discriminant analysis generally demonstrated good class separation based on the maximal severity of ultrasound finding in each acoustic window. Lung ultrasound performed poorly at detecting bronchopneumonia. Bovine ultrasounds looked similar to human infant lung ultrasounds. Conclusion Point-of-care lung ultrasound abnormalities reflect lung pathology at the histological level in a bovine calf model of bronchiolitis. Point-of-care lung ultrasound images in human infants are similar to those obtained in calves.

Lung ultrasound allows for earlier diagnosis of bronchiolitis than auscultation: an animal experiment and human case series

“…The methods are as described the first article [18] in this series. Briefly, we experimentally infected 24 5-week-old pre-ruminant Holstein bull calves (Bos taurus) with bovine RSV [7].…”

“…We searched hospital medical records from RSV season in 2015 and 2019. Unlike the first article in this series [18] the comparative rarity of infants in whom a physician had performed a point-of-care lung ultrasound seeking evidence of bronchiolitis in the absence of auscultatory findings required a more extensive electronically assisted search of our hospital's medical records over a longer period of time.…”

“…Data were exported to Stata 16.1 statistical software (Statacorp LLP, College Station, TX) for data management and analysis. Ultrasound scores were calculated as described in the first article in this series 1 3 and Table 1 [18]. We plotted the standardized clinical score excluding temperature component, and the standardized respiratory rate against the standardized ultrasound scores for each animal for each day.…”

“…We hypothesized that point-of-care lung ultrasound would allow for earlier diagnosis of bronchiolitis than auscultation. Because we cannot deliberately infect infants with RSV we used an experimental approach with a bovine model (which we describe in article 1 in this series [18]) and an observational approach in human infants seeking out cases where our pediatric emergency physicians had attempted to use ultrasound for early diagnosis.…”