Roth, Grace M.

Eight hundred fifty-seven determinations of the pH of venous blood with simultaneous blood pressure observations were carried out on 590 patients. The pH of venous blood of the patients who had been under medication for a long period before the tests did not vary significantly from that of patients who had had no medication. The most consistent result was the rise in the pH of venous blood 30 minutes after a dose of phentolamine hydrochloride (Regitine). The oral administration of 40 grains of sodium bicarbonate did not increase the response of the blood pressure during the histamine test, irrespective of the type of previous medication, even though the pH of the venous blood was low initially and rose to normal levels after the administration of the sodium bicarbonate. This may be due to the fact that none of the patients had pheochromocytomas with excessive release of pressor amines.

A group of 26 patients who had peripheral occlusive arterial disease of the lower extremity were studied before and after chemical or surgical unilateral lumbar sympathectomy. The temperatures of the gastrocnemius muscle and of the skin of the sural area were determined simultaneously preoperatively and postoperatively. Only patients who had undergone successful unilateral lumbar sympathetic denervation based on the postoperative area of anhidrosis were included. The data were obtained under basal conditions among the 26 patients, and the persons studied were divided into two groups. Group 1 was composed of 17 patients (65 per cent) who had a definite parallel increase of 1.2 C. in the temperature of the gastrocnemius muscle and the skin after unilateral sympathectomy. In group 2 (nine patients or 35 per cent) the temperature of the gastrocnemius muscle and the skin of the sural area was unchanged after unilateral sympathectomy. Since none of these patients were suitable for surgical bypass arterial-grafting procedures and all were in the older age group, not too much could be expected from the standpoint of an increase in temperature. However, when the temperature of the skin after operation increased, the temperature of the gastrocnemius muscle also increased.

Bilateral determinations of the blood pressures were made nonsimultaneously and simultaneously by the indirect method under basal conditions on 447 patients. In this group 26.6 per cent of the paired measurements by the nonsimultaneous indirect method exhibited systolic differences of 10 mm. Hg or greater and 15 per cent exhibited diastolic differences of this magnitude, whereas only 5.3 per cent of the measurements by the simultaneous indirect method had systolic differences and only 4 per cent had diastolic differences of this degree. This indicates that bilateral determinations of blood pressure must be performed simultaneously on patients being examined for possible inequalities of blood pressure. Bilateral differences in blood pressure obtained by the simultaneous indirect and simultaneous direct methods in 14 normal subjects and 53 selected patients were compared. In the normal subjects, 3 of the 42 paired indirect measurements and none of the paired direct measurements in either the radial or brachial arteries had systolic differences of 10 mm. Hg or greater, and none of the diastolic differences were of this level. In the 53 selected patients, 10 per cent of the indirect and 6 per cent of the direct measurements of systolic blood pressure differed by 10 mm. Hg or more and 8 per cent of the paired indirect measurements of diastolic blood pressure and less than 1 per cent of the paired direct measurements differed by this amount. These differences in bilateral blood pressures were characterized by their inconstancy and lack of agreement with subsequent measurements when studied by both the indirect and direct methods, which apparently separates them from those due to altered hemodynamics from pathologic conditions of the aortic arch or its tributaries. Bilateral differences of blood pressure are of clinical importance when they are great and are reproducible by the direct as well as by the indirect methods, as illustrated by a patient encountered in this study. In addition, 1 case of extreme obesity and 1 of advanced arteriosclerosis were reported. Both patients were found to have pseudohypertension, which was detected in this study. A slight increase in the incidence of bilateral differences in indirect blood pressures was found in a group of patients whose blood pressures were measured while they were in the supine and then in the sitting position. A slight increase in the incidence of bilateral differences was found at higher levels of blood pressure by comparing the blood pressures of nonhypertensive and hypertensive patients and of hypertensive patients before and during treatment with antihypertensive drugs. Bilateral inequalities of blood pressure did not appear to be related to the age or sex of the subjects. Likewise, differences in circumferences of the arm or right or left-handedness did not appear to influence these inequalities, and there was no marked side dominance for differences found. Bilaterally simultaneous, indirect measurements of blood pressure should be carried out on patients with hypertension who will be treated with antihypertensive drugs. Bilateral direct measurements may be used to verify the existence of inequality of blood pressures detected by the indirect method and to determine the correct pressure to be followed. This is particularly important in patients being screened for pheochromocytomas, since such differences may produce false-positive results.

Today pharmacologic and chemical tests are helpful in screening a relatively large number of patients for pheochromocytoma and are a definite aid to a correct diagnosis. No one test is infallible, and knowledge concerning the drugs used or the manner in which the blood and urine are collected, or both, is necessary to avoid a false-positive or false-negative result from the tests.