Question 18

Draw and numerically label, on a spirogram, the lung volumes and capacities of a 30 kg child.

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College Answer

This core respiratory physiology topic was well answered by most candidates. Candidates
generally were able to draw a spirogram. A common omission was inspiratory capacity. 


The "child" thing was left here probably as some sort of cruel distractor. The weight suggests a kid of about nine-ten years old, and at this age the respiratory dimensions are sufficiently adultish that no major adjustments need to be made to adult weight-based formulae. For comparison, here the numbers quoted by Kerry Brandis are compared with some ancient published data from Morse & Schlutz (1952)

Normal Reference Values for Lung Volumes and Capacities
Volume In ml/kg, 
from Brandis
In ml, for 30kg child,
from Brandis
In ml, for 30kg boy,
from Morse & Schlutz (1952)
RV 15 450 575
ERV 15 450 445
TV 7 210  
IRV 45 1350  
IC 52 1560 1654
FRC 30 900 1020
VC 67 2010 2099
TLC 82 2460 2738

Thus, the diagram would look like this:



Morse, Minerva, Frederic W. Schlutz, and Donald E. Cassels. "The lung volume and its subdivisions in normal boys 10-17 years of age." The Journal of clinical investigation 31.4 (1952): 380-391.

Wanger, J., et al. "Standardisation of the measurement of lung volumes." European respiratory journal 26.3 (2005): 511-522.

Lutfi, Mohamed Faisal. "The physiological basis and clinical significance of lung volume measurements." Multidisciplinary respiratory medicine 12.1 (2017): 3.

Boren, Hollis G., Ross C. Kory, and James C. Syner. "The Veterans Administration-Army cooperative study of pulmonary function: II. The lung volume and its subdivisions in normal men." The American Journal of Medicine 41.1 (1966): 96-114.

Neder, Jose Alberto, et al. "Reference values for lung function tests: I. Static volumes." Brazilian journal of medical and biological research 32.6 (1999): 703-717.