[A study of hemodynamic effects during dental treatment under local anesthesia. Observation of parasympathetic activity based on the index of R-R interval variation in ECG].

Observing hemodynamic changes occurring during dental treatment performed under local anesthesia is very important. Although many reports on such changes have been made on the basis of blood pressure and heart rate indexes, few have been made on the basis of parasympathetic activity. This is a report of a study on observations of parasympathetic activity on the basis of the index of R-R interval variation in ECG. A multipurpose monitoring system was used to observe and record hemodynamic changes in 52 patients undergoing dental treatment under local anesthesia. In addition, parasympathetic activity was observed on the basis of the index of the coefficient of variation of the R-R interval in ECG (CVR-R = SD/MEAN x 100%). To evaluate R-R interval variations in ECG during dental treatment clearly, comparisons were made between subjects to whom atropine sulfate was administered (prior to treatment) and subjects to whom no drug was administered. In instances of which the subject experiences no unpleasant symptom (for instance, the fainting) during dental treatment, comparative examinations of R-R interval variations in ECG were made at various points during the course of therapy. In instances of which the fainting was induced, examinations of these variations were made during, before, and after the occurrence of the fainting. Results and Conclusions 1. In measuring R-R interval variations in ECG, maintaining stable heart rates and respiratory frequency and depth made it possible to evaluate parasympathetic activity during dental treatment. 2. Consistently low CVR-R values after administration of atropine sulfate clearly showed that patients treated in this way were in a state of parasympathetic blockade. 3. Patients to whom atropine sulfate was administered demonstrated higher values for systolic and diastolic blood pressure and for heart rate than controls: and their posttreatment recovery was slower. 4. Increasing age produced a correlative decrease in CVR-R during both the pretreatment rest period and immediately before treatment. 5. Systolic and diastolic blood pressure and heart rate increased at local anesthesia and maintained such levels until the end of treatment in no fainting cases, however, CVR-R increased just before the end of treatment. This finding leads to the assumption that, as a result of intensified sympathetic activity at the initial stage and the maintenance of this condition, parasympathetic activity increases just before the end of therapy to keep hemodynamic activity in balance.(ABSTRACT TRUNCATED AT 400 WORDS)