Kenneth M. Lynch

APPARATUS LEAK AS A CAUSE OF FALSE LOW BASAL METABOLISM READINGS

To the Editor: —Basal metabolism determinations having become of the widest clinical use, it is well for all concerned in the performance of the test to be informed about every pitfall which may be encountered. As a general proposition, whenever a leak occurs in the apparatus used for the test, it will give an apparent increase in oxygen consumption, and consequently a false positive reading. This is, apparently, because a certain degree of positive pressure in the machine is developed by each exhalation, a certain amount of air being forced out at each respiration; whereas, inhalation does not create a negative pressure sufficient to cause the same amount of intake through the leak. The variation from the true consumption of oxygen is dependent on the amount of air escaping through the leak. Usually the presence of a leak in the apparatus is easily determined, and no test should be performed