Hyperventilation and sphygmomanometry.

To the Editor.— During 30 years of practice, I have relied on hyperventilation to determine if the patient really has high blood pressure or whether the elevation of blood pressure is due to tension factors. Since so much emphasis is correctly being placed on treatment of hypertension, it is important not to treat patients unless they need treatment. Many patients, when first examined and even after repeated visits to the same physician, will have an elevated blood pressure that falls to normal after a minute or two of hyperventilation. Some patients seem to react with a high reading simply by having the blood pressure cuff put on their arms and do not have true hypertension. I have asked many physicians interested in cardiovascular disease, and they do not know of any work that has been done on this. They seem to have no interest or enthusiasm in doing any investigative