Reproducibility is more than ever an inevitable topic in
research. Recently, the subject was
addressed by Dr. Jason Bates1 specifically in relation to
preclinical lung function measurements.
As explained in this interesting article, lung function measurements
are affected by a number of confounding factors and controlling for them ensures
that the subjects are studied under the same conditions, which helps generate
robust data that can be reproduced by others.
According to Dr. Bates, controlled experimental conditions
including anaesthesia and mechanical ventilation are needed to achieve high-quality
preclinical lung function data1, 2. However, it is known that under these
conditions, there is a progressive loss in lung volume due to airway closure or
collapse3. Additionally, as
can be seen in a number of studies, once closed, airspaces do not spontaneously
re-open. A high-pressure manoeuver, such
as a deep lung inflation, is typically required to open-up closed airways4,
5 or completely collapsed lungs6. Therefore, as reported in the article at hand1,
it is key to start a preclinical lung function experiment with a deep inflation
to standardize lung volumes across subjects at baseline.
DEEP INFLATION
Technical Description
- The deep inflation gradually inflates the subject’s lungs to a pressure of 30 cmH2O over a period of 3 seconds.
- The lungs are then held at that pressure for another 3 seconds, time during the alveolar pressure is allowed to equilibrate to the applied pressure.
- The initial and end volumes are used in the calculation the inspiratory capacity (IC).
- The Deep Inflation perturbation brings the subject’s lungs from end of expiration (FRC) to total lung capacity (TLC), which is defined by default as a pressure of 30 cmH2O.
- It provides a direct measurement of the subject’s inspiratory capacity.
References
1.
Bates, JHT.
2017. CORP: Measurement of lung
function in small animals. J Appl Physiol, in press, DOI:
10.1152/japplphysiol.00243.2017.
2.
Bates
JH, Irvin CG. 2003. Measuring lung function in mice: the
phenotyping uncertainty principle. J Appl Physiol 94: 1297-306.
3. Mead
J, Collier C. 1959. Relation of volume history of lungs to
respiratory mechanics in anesthetized dogs.
J Appl Physiol 14: 669-678.
4.
Wagers
S, Lundblad LK, Ekman M, Irvin CG, Bates JH.
2004. The allergic mouse model of
asthma: normal smooth muscle in an abnormal lung? J Appl Physiol 96: 2019-27.
5.
Shalaby
KH, Gold LG, Schuessler TF, Martin JG, Robichaud A. 2010.
Combined forced oscillation and forced expiration measurements in mice
for the assessment of airway hyperresponsiveness. Respir Res 11: 82.
6. Limjunyawong N, Fallica J, Horton MR,
Mitzner W. 2015. Measurement of the pressure-volume curve in
mouse lungs. Journal of visualized experiments: J Vis Exp 95: 52376.
