Changes of plasma catecholamine concentrations and fingertip plethysmogram in local anesthesia and tooth extraction.

To clarify the significance of fingertip plethysmogram as an intraoperative monitor, changes in the blood catecholamine level and the fingertip plethysmogram were measured with time. These measurements were compared under local anesthesia during the extraction of an impacted mandibular third molar. A total of 60 subjects were selected for the study of which 40 were without any abnormality in their cardiovascular system and the remaining 20 had an impacted mandibular third molar. All subjects were healthy adult males with their ages ranging from 20 to 30 years old.The following results were obtained through this experiment.1) The subjects showed no marked changes in the blood catecholamin level and the fi ngertip plethysmogram under local infiltration anesthesia induced by 2% lidocaine.2) The subjects showed a significant increase in the epinephrine and norepinephrine levels, average arterial pressure, and pulse rate under local infiltration anesthesia induced by 1/80, 000 epinephrin-containing 2% lidocaine. They also exhibited a significant decrease in the wave hight and incisura hight of the fingertip plethysmogram. The norepinephrine level, the average arterial pressure, and the pulse rate decreased rapidly to the levels almost equivalent to the values obtained after rest. In contrast, the elevated epinephrine level and the decreased wave and incisura heights continued over 45 minutes. Since these changes were not observed during the 2% lidocaine-induced local infiltration anesthesia, the exogenous epinephrine is believed to considerably in fluence these changes.3) During the impacted mandibular third molar extraction, the subjects exhibited similar changes to those observed during the infiltration anesthesia induced by 1/80, 000 epinephrinecontaining 2% lidocaine. However, the recovery of the epinephrine level and of the wave and incisura bights required approximatery 10 minutes longer during the molar extraction. These results suggest that the influence of endogenous catecholamine was added to the influence of exogenous epinephrine.4) There was a significant correlation between epinephrine levels and the wave bights of plethysmogram during infiltration anesthesia induced by 1/80, 000 epinephrine-containing 2% lidocaine and mandibular third molar extraction. These results have clarified the following facts: The blood catecholamine level and the fingertip plethysmogram changed during local infiltration anesthesia and mandibular third molar extraction. These changes persisted even after the recovery of hemodynamics by the autoregulatory mechanism. Finally, the fingertip plethysmogram was well correlated with the blood epinephrine levels.