Maximum Voluntary Ventilation in a Population Residing at 2,240 Meters Above Sea Level

Measured maximum voluntary ventilation (MVV) correlates with maximum ventilatory capacity during exercise. As a shortcut, MVV is often estimated by multiplying measured FEV₁ times 35 or 40, but this index varies with altitude due to reduced air density. The objective was to describe MVV in healthy individuals residing at 2,240 m above sea level and compare it with the reference values customarily employed.

We recruited a convenience sample of respiratory-healthy, non-obese volunteers >10 y of age who had resided for >2 y in Mexico City. All participants performed forced spirometry and MVV according to current standards. Multiple regression models were fitted, including age, height, and measured FEV₁, separately for males and females to obtain reference values. The impact of lower air density on MVV at this elevation was estimated from the reported increase in peak flow in relation to altitude.

We studied 381 individuals (210 females [55.1%]) age 10-80 y with a mean MVV of 145.6 ± 48 L/min. Both FEV₁ × 35 and FEV₁ × 40 underestimated the MVV observed: in males by approximately 26% and in females by approximately 10%. MVV for our population approached FEV₁ × 45 (98 ± 15.6% of real MVV). Multiple regression models including height, weight, and measured FEV₁ explained 70% of residual variability once sex was taken into account.

At an altitude of 2,240 m, MVV is about 45 times the measured FEV₁, and it can be estimated for other altitudes. The best predicting equations for MVV were calculated separately for females and males and included the following predictors: age, age², and measured FEV₁. The study found that reference values for MVV from studies conducted at sea level are inaccurate at this altitude.