Question 18
Draw and numerically label, on a spirogram, the lung volumes and capacities of a 30 kg child.
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.
Discussion
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):
| 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:
References
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.