UMEM Educational Pearls

Category: Critical Care

Title: Do Little People Have Little Lungs?

Keywords: Achondroplasia, vertebral arteries, mechanical ventilation (PubMed Search)

Posted: 6/11/2019 by Robert Brown, MD (Updated: 10/18/2019)
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Takeaways

Little people (patients with achondroplasia or "dwarfism") have little lungs. Even though the trunk may appear to be a normal size with small limbs, the vital capacity is actually about 75% the predicted value based on the patient's sitting height. Macrocephaly and a decreased anterior-posterior depth are the cause for this. When you want to mechanically ventilate a little person, you can estimate their height based on a typical person with the same sitting height, but their actual volume will be about 3/4 the tidal volume predicted.

When intubating, remember these patients also have a high risk of basicranial hypoplasia (the foramen magnum may be small and key-hole shaped). These patients will be predisposed to compress the vertebral arteries when you tilt the head back and this itself can cause ischemia of the medulla and pons leading to central apnea.

Stokes DC, Wohl ME, Wise RA, et al. The lungs and airways in Achondroplasia. Do little people have little lungs? CHEST. 1990; 98(1):145-52

Pauli RM. Achondroplasia: A comprehensive review. Orphanet Journal of Rare Diseases. 2019; 14(1): 

 

 

In-Depth


References

Stokes DC, Wohl ME, Wise RA, et al. The lungs and airways in Achondroplasia. Do little people have little lungs? CHEST. 1990; 98(1):145-52

Pauli RM. Achondroplasia: A comprehensive review. Orphanet Journal of Rare Diseases. 2019; 14(1):