Estimation of response slopes in respiratory control using directional statistics.

The ventilatory sensitivity to alveolar PCO2 and slope of the straight line relating VE to VT are two examples of response slopes of interest in respiratory control. Statistical techniques have not been available to analyze repeated direct estimations of these slopes by paired consideration of initial and final responses to a stimulus. Rather, existing statistical techniques sacrifice much information by describing the response slope as that of the line which, in some sense, best fits the unpaired responses. We have adapted techniques established for the statistical analysis of directional data to analyze direct measurements of these physiological response slopes and have found that the application of these directional techniques can result in better estimation of the ventilatory sensitivity to CO2, for example, than is provided using unpaired analysis techniques.