Related Experiment Videos
Postnatal development of respiratory function in lambs studied serially between birth and 8 weeks
M G Davey1, D P Johns, R Harding
1Department of Physiology, Monash University, Clayton, Victoria, Australia. m.davey@med.monash.edu.au
Insights
Respiratory function in lambs changes significantly in the first 8 weeks after birth. Pulmonary diffusing capacity increases due to alveolar development, while lung volumes and breathing patterns mature.
Area of Science:
- Physiology
- Neonatal Development
Background:
- Understanding neonatal respiratory development is crucial for identifying potential long-term health issues.
- Previous research has limited serial data on respiratory function in the early postnatal period of lambs.
Purpose of the Study:
- To quantify developmental changes in key respiratory parameters in lambs during the first 8 postnatal weeks.
- To establish a reference dataset for postnatal lung function in sheep.
Main Methods:
- Repeated measurements of respiratory function in 12 pentobarbitone-sedated lambs from 3 days to 8 weeks postnatal.
- Assessment of pulmonary diffusing capacity, lung volumes (Total Lung Capacity, Functional Residual Capacity), respiratory system compliance, and breathing patterns.
Main Results:
- Pulmonary diffusing capacity for CO increased with age, driven by alveolar-capillary membrane diffusion (Dm) and pulmonary capillary blood volume (Vc).
- Total lung capacity and Functional Residual Capacity (FRC) decreased postnatally.
- Static respiratory system compliance initially fell rapidly, primarily due to reduced chest wall compliance.
Conclusions:
- Serial assessment of respiratory function in sedated lambs is feasible using basic methods.
- Postnatal increases in pulmonary diffusing capacity reflect ongoing alveolarization.
- The study provides essential normative data for future research on prenatal influences on postnatal lung function in sheep.
Abstract:
We have quantified developmental changes in major aspects of respiratory function in 12 pentobarbitone-sedated lambs by making repeated measurements during the first 8 postnatal weeks, between term birth and post-weaning. Pulmonary diffusing capacity for CO increased with age due to increases in both the diffusing capacity of the alveolar capillary membrane (Dm) and pulmonary capillary blood volume (Vc). Total lung capacity measured at a lung inflation pressure of 30 cmH2O decreased from 74.4 +/- 3.2 ml/kg at 3 days to 47.2 +/- 2.9 ml/kg at 8 weeks. Static respiratory system compliance, measured between FRC and TLC fell rapidly during the first 3 weeks, then remained unchanged; the early postnatal fall was largely due to a reduction in chest wall compliance as lung compliance was constant. FRC declined from 32.3 +/- 1.7 ml/kg at 3 days to 25.1 +/- 1.5 ml/kg at 2 weeks, then fell to 21.4 +/- 1.2 ml/kg by 8 weeks. Specific pulmonary conductance (conductance/FRC) during mid-inspiration and mid-expiration did not change with age (0.195 +/- 0.012 and 0.194 +/- 0.019 L x sec(-1) x cmH2O(-1) x L(-1)-FRC, respectively). Breathing frequency, and weight-adjusted tidal volume and minute ventilation declined after birth until 4 weeks after which they did not change. This study has shown that, using basic methodology, serial assessments of respiratory function can be obtained in sedated lambs from soon after birth. The age-related increase seen in pulmonary diffusing capacity is due to increases in both Dm and Vc, which are consistent with continuing alveolarisation. Our data on age-related changes in pulmonary function and volumes provide a reference for future studies on the effect of altered prenatal lung development on postnatal lung function in sheep.