Butz et al. (A-11) studied the use of noninvasive positive-pressure ventilation by patients with amyotrophic lateral sclerosis. They evaluated the benefit of the procedure on patients’ symptoms, quality of life, and survival. Two variables of interest are PaCO2, partial pressure of arterial carbon dioxide, and PaO2, partial pressure of arterial oxygen. The following table shows, for 30 subjects, values of these variables (mm Hg) obtained from baseline arterial blood gas analyses.

PaCO2 PaO2 PaCO2 PaO2 PaCO2 PaO2 40 101 54.5 80 34.5 86.5 47 69 54 72 40.1 74.7 34 132 43 105 33 94 42 65 44.3 113 59.9 60.4 54 72 53.9 69.2 62.6 52.5 48 76 41.8 66.7 54.1 76.9 53.6 67.2 33 67 45.7 65.3 56.9 70.9 43.1 77.5 40.6 80.3 58 73 52.4 65.1 56.6 53.2 45 66 37.9 71 59 71.9 Source: M. Butz, K. H. Wollinsky, U. Widemuth-Catrinescu, A.
Sperfeld, S. Winter, H. H. Mehrkens, A. C. Ludolph, and H.
Schreiber, “Longitudinal Effects of Noninvasive Positive-Pressure Ventilation in Patients with Amyotrophic Lateral Sclerosis,” American Journal of Medical Rehabilitation, 82 (2003) 597–604.
On the basis of these data may we conclude that there is an association between PaCO2 and PaO2 values? Let a ¼ :05.