Measurement of exchangeable sodium by isotope dilution is a relatively simple, reliable method for the determination of body sodium contents, which can be used in the clinical practice without significant health hazard to the patient. When computed to body surface area, the values for exchangeable sodium can be compared in patients of different body build. Exchangeable sodium may be variably increased in different clinical conditions associated with hypertension, thus increased sodium contents of the body is of major importance in the pathogenesis of hypertension caused by all forms of mineralocorticoid excess, and in the majority of patients with chronic renal insufficiency. In several endocrine disorders, e. g., acromegaly, hypothyroidism, increased sodium space does not play any significant part in the pathogenesis of hypertension. In diabetes mellitus, exchangeable sodium may be increased already prior to the development of hypertension, however it is still a matter of debate whether this abnormality is involved in the pathogenesis of hypertension in these patients. It seems now beyond any doubt that body sodium is normal in patients with essential hypertension, including those with the low renin form of the disease; nevertheless, some data indicate that blood pressure may be volume dependent in elderly patients with essential hypertension.
Sudden and large increase of the blood pressure may be life-threatening, particularly when they are accompanied by encephalopathy, left-ventricular insufficiency or other complications. The crisis of hypertension shall be treated possibly without loss of time and with energy. If there is the possibility for a permanent control of the patient, the infusion by drops of nitroprusside sodium is the therapy of choice. It at once decreases the blood pressure and is free of side-effects. Diazoxide has the advantage compared with nitroprusside sodium that an intravenous injection decreases the blood pressure for several hours. But the rapid and drastic decrease of blood pressure may occasionally be dangerous in patients with coronary insufficiency and cerebral arteriosclerosis. In certain indications also other medicaments, such as reserpine, alpha-methyldopa, phentolamine, saralasin or nifedipine can be applied. The crisis of hypertension is always to be regarded as an emergency situation, since always irreversible lesions may be appear on the different organs as a sequel of the permanent vasoconstriction and ischaemia.
The aim of the study was to evaluate the accuracy of the most widespread 24-hour ambulatory blood pressure monitor in Hungary. The test was based on simultaneous measurement on the same arm with the test device and standard zero or random zero sphygmomanometer in 100 patients. The difference between the blood pressure values measured by the test device and by the standard device was calculated in each case, and a relationship between this difference and the actual blood pressure of the patient was analysed. Actual blood pressure was considered as the average of the blood pressure measured by the test and that by the standard device. Regarding the diastolic values, the mean difference between the values obtained by the test device and the standard zero sphygmomanometer was -3.8 +/- 7.55 mm Hg (p > 0.05), and that between the test device and the random zero sphygmomanometer was -0.1 +/- 6.05 mm Hg (p > 0.05). This differences did not reach statistical significance. Regarding the systolic values, the difference showed significant positive correlation with the actual blood pressure level of the patient, meaning that at higher blood pressure values the difference between the data gained by the test and standard device is greater than at lower actual blood pressure levels. Finally, according to the criteria of the British Hypertension Society, our device could be graded "C" both for diastolic and systolic values against the standard zero sphygmomanometer, and "C" for systolic and "B" for diastolic blood pressure against the random zero sphygmomanometer.
