Standard Spirometer Research Articles

Further simplification of a method for determination of residual lung volume

This paper describes a modification of the standard oxygen-dilution technique for determining residual lung volume, whereby rapid responding oxygen and carbon dioxide analyzers are used to determine the point of nitrogen equilibration, and a five-liter rebreathing bag is substituted for the standard spirometer. This simplified method reduced the total test time to five min or less for duplicate determinations, and eliminated the need for a nitrogen analyzer and a spirometer. This method was found to be both reliable (r = 0.99) and valid (r = 0.92), with a standard error of prediction of 125 ml, and a mean difference of only eight ml, when compared with the established oxygen-dilution technique on a sample of 76 healthy men and women, 19 to 55 years of age. In a subsample of 13 subjects, residual volume was also determined with the nitrogen washout technique, which correlated r = 0.89 and r = 0.91 with the established and modified oxygen-dilution techniques respectively. The use of assumed values for the initial and final alveolar concentrations of nitrogen did not appear to significantly influence the final results.

A METHOD OF SPRIOMETRY DURING GENERAL ANAESTHESIA

SUMMARY A standard spirometer (Spirotest III) was modified for use in anaesthesia. Though filled with oxygen, anaesthesia was maintained by injecting small quantities of liquid halothane into the circuit. During spontaneous breathing tidal volume, respiratory rate, minute volume and oxygen consumption can easily be measured.