COMMUNICATIONS T O THE EDITOR Exercise Tolerance Increased by Oxygen Therapy or Psychologic Factors?
We submit that the effect of the oxygen therapy in the 12 patients of Block et al, was in great part psychologic, and we disagree with their conclusion that the oxygen resulted in the increase in exercise tolerance. A more definitive answer seems within reach if with the next study, air given by mask or cannula were used as a control treatment measure, and a double blind design were utilized.
Gerald L. Baum, M.D. Veterans Administration Hospital Cleveland, Ohio
To the Editor: In the March 1974 issue of Chest (65:279-288), Drs. Block, Castle and Keitt have ascribed to oxygen therapy of COLD (chronic obstructive lung disease) patients, results which we feel may well be related to other aspects of management. We acknowledge that administration of oxygen to hypoxemic COLD patients (at sea level) will regularly lead to increased PaOp, as many studies have documented and as Block and his associates clearly demonstrated. Moreover, the change in hematologic indices with oxygen therapy is consistent. No argument so far. However, we are at odds with the authors in their conclusion that the observed increase in exercise tolerance was due to the changes in PaO2. The data presented by the authors in four of their 12 cases showed no change in hemodynamic measurements after four weeks of oxygen therapy. If cardiovascular function was not improved, then the effect of oxygen on exercise tolerance could only have been due to the direct effect of the increased Pa02 on skeletal muscle function, and no data were presented in support of that thesis. In fact, the lack of change in lactate levels and the variability of 2,3DPG levels may be evidence against this contention. In work reported from our center, 22 of 23 patients significantly increased their exercise tolerance without oxygen therapy after a four-week training period in a special rehabilitation program.' Extensive physiologic and psychologic testing demonstrated that no change in pulmonary or cardiac physiology occurred but fairly constant psychologic changes were documented. From this we concluded that the psychologic responses of some patients with COLD reflect fear, depression, anxiety and hypochondriac tendencies. The sensitivity, concern and competence of a treatment team or person help allay these debilitating reactions, and the encouragement communicated through the therapists' consistent interest in the patients' problems, urges the latter to push their exercise to levels that they could not previously have attained. Thus the patients are literally desensitized to their dyspnea and the panic it engenders. 736 COMMUNICATIONS TO THE EDITOR
1 Agle DP, Baum GL, Chester EH, et al: Multidiscipline treatment of chronic pulmonary insufficiency. 1 Psychological aspects of rehabilitation. Psychosom Med 35:41,1973
To the Editor: In response to Dr. Baum's criticism I should like to point out several apparent differences between his study and ours. First, the severe degree of physiologic disability was clearly defined in our study. I was unable to find either pulmonary function studies or arterial blood gas measurements in the report .which he cited. Second, we were able to measure at least a 50 percent improvement in exercise tolerance in 11 of 12 patients immediately after the institution of oxygen therapy, whereas his studies were performed after one month and one year of rehabilitation. I point out these differences because I believe that we are dealing with a different severity of lung disease. The exercise tolerance of our severely hypoxemic patients was limited by obvious cyanosis, a measured decrease in arterial oxygenation, severe dyspnea, and an obvious inability to continue. Zmmediately thereafter, oxygen was administered and the treadmill test repeated. The same patient was then able to complete a greater degree of exercise despite having been tired from the initial study. Additionally, arterial oxygenation was measured and found to be improved at all levels of exercise. It is difficult for me to understand how improvement in psychologic status could effect this immediate increase in exercise tolerance, relief of hypoxemia, and disappearance of cyanosis. On the other hand, additional improvement occurred in our study after four weeks of oxygen therapy. This additional improvement could well be related to the psychologic improvement which Drs. Castle, Keitt and I measured. Such further improvement would correspond to the one month findings of Drs. Agle, Baum, Chester, et al. Indeed, such questions would be resolved if a sham study with air CHEST, 67: 6, JUNE, 1975
We submit that the effect of the oxygen therapy in the 12 patients of Block et al, was in great part psychologic, and we disagree with their conclusion that the oxygen resulted in the increase in exercise tolerance. A more definitive answer seems within reach if with the next study, air given by mask or cannula were used as a control treatment measure, and a double blind design were utilized.
Gerald L. Baum, M.D. Veterans Administration Hospital Cleveland, Ohio
To the Editor: In the March 1974 issue of Chest (65:279-288), Drs. Block, Castle and Keitt have ascribed to oxygen therapy of COLD (chronic obstructive lung disease) patients, results which we feel may well be related to other aspects of management. We acknowledge that administration of oxygen to hypoxemic COLD patients (at sea level) will regularly lead to increased PaOp, as many studies have documented and as Block and his associates clearly demonstrated. Moreover, the change in hematologic indices with oxygen therapy is consistent. No argument so far. However, we are at odds with the authors in their conclusion that the observed increase in exercise tolerance was due to the changes in PaO2. The data presented by the authors in four of their 12 cases showed no change in hemodynamic measurements after four weeks of oxygen therapy. If cardiovascular function was not improved, then the effect of oxygen on exercise tolerance could only have been due to the direct effect of the increased Pa02 on skeletal muscle function, and no data were presented in support of that thesis. In fact, the lack of change in lactate levels and the variability of 2,3DPG levels may be evidence against this contention. In work reported from our center, 22 of 23 patients significantly increased their exercise tolerance without oxygen therapy after a four-week training period in a special rehabilitation program.' Extensive physiologic and psychologic testing demonstrated that no change in pulmonary or cardiac physiology occurred but fairly constant psychologic changes were documented. From this we concluded that the psychologic responses of some patients with COLD reflect fear, depression, anxiety and hypochondriac tendencies. The sensitivity, concern and competence of a treatment team or person help allay these debilitating reactions, and the encouragement communicated through the therapists' consistent interest in the patients' problems, urges the latter to push their exercise to levels that they could not previously have attained. Thus the patients are literally desensitized to their dyspnea and the panic it engenders. 736 COMMUNICATIONS TO THE EDITOR
1 Agle DP, Baum GL, Chester EH, et al: Multidiscipline treatment of chronic pulmonary insufficiency. 1 Psychological aspects of rehabilitation. Psychosom Med 35:41,1973
To the Editor: In response to Dr. Baum's criticism I should like to point out several apparent differences between his study and ours. First, the severe degree of physiologic disability was clearly defined in our study. I was unable to find either pulmonary function studies or arterial blood gas measurements in the report .which he cited. Second, we were able to measure at least a 50 percent improvement in exercise tolerance in 11 of 12 patients immediately after the institution of oxygen therapy, whereas his studies were performed after one month and one year of rehabilitation. I point out these differences because I believe that we are dealing with a different severity of lung disease. The exercise tolerance of our severely hypoxemic patients was limited by obvious cyanosis, a measured decrease in arterial oxygenation, severe dyspnea, and an obvious inability to continue. Zmmediately thereafter, oxygen was administered and the treadmill test repeated. The same patient was then able to complete a greater degree of exercise despite having been tired from the initial study. Additionally, arterial oxygenation was measured and found to be improved at all levels of exercise. It is difficult for me to understand how improvement in psychologic status could effect this immediate increase in exercise tolerance, relief of hypoxemia, and disappearance of cyanosis. On the other hand, additional improvement occurred in our study after four weeks of oxygen therapy. This additional improvement could well be related to the psychologic improvement which Drs. Castle, Keitt and I measured. Such further improvement would correspond to the one month findings of Drs. Agle, Baum, Chester, et al. Indeed, such questions would be resolved if a sham study with air CHEST, 67: 6, JUNE, 1975
