Dyspnea proneness to CO2 stimulation and personality (neuroticism, extraversion, MMPI factors).

The relationship between extroversion (E), MMPI factors on the one hand and the ventilatory response to CO2 on the other was examined in order to extend and clarify earlier studies. 30 male nonsmokers were studied using the method of Read (delta VE/PaCO2 as index of readiness to react with dyspnea upon CO2 stimulation). Extroversion (E) and neuroticism (N) was assessed by the Eysenck Personality Test. The panic-fear (PF) and the ego-strength (Es) scales were extracted from the MMPI. The correlation between E, N, MMPI values and delta VE/PaCO2 was measured with Pearson's correlation. Reliability between the first and second respiratory test was obvious, r = 0.66 (p less than 0.001). The correlation between the psychological parameters and the readiness to respond to CO2 was very low in the first test. In the second test, the r for hypochondriasis, depression and PF was 0.25, 0.28 and 0.29, respectively (p less than 0.1; 2-tailed), for N the r was 0.33, for psychastheny 0.33, and for Es -0.40 (all p less than 0.05). In agreement with Saunders and co-workers, we found no correlation for E. Our results indicate that readiness to react to CO2 is related to anxiety (positive correlations for N, Hs, Pt and PF, and negative for Es). This corresponds to clinical observations.