ASSESSMENT OF AUTONOMIC NERVOUS ACTIVITY DURING GASTROINTESTINAL ENDOSCOPY - ANALYSIS OF BLOOD-PRESSURE VARIABILITY BY TONOMETRY

We continuously measured blood pressure by tonometry in 30 patients du ring endoscopy to determine the influence of upper gastrointestinal en doscopy on cardiac events. Patients were divided into two groups: one group treated with scopolamine butylbromide as premedication (SB group ) and another group without premedication (C group). Time- and frequen cy domain analyses of beat-to-beat systolic blood pressure variability were performed for 128 consecutive beats. For time-domain analysis, w e calculated the coefficient of variation of systolic blood pressure ( CVBP). For the frequency domain analysis, we determined the low-freque ncy (LFBP; 0.04-0.15 Hz) and high-frequency (HFBP; 0.15-0.40 Hz) power s of the variation in systolic blood pressure and the ratio of LFBP to HFBP (LFBP/HFBP) during endoscopy. The CVBP and HFBP, indicators of p arasympathetic tone, increased in the early phase of endoscopy but dec reased significantly in the middle and late phases compared with the p re-endoscopy value. The ratio of LFBP/HFBP, an indicator of indirect s ympathetic tone, increased throughout the endoscopic procedure. Moreov er, premedication with scopolamine butylbromide prevents the excessive parasympathetic nervous reflex when an endoscope passes through the u pper digestive tract and also brings both decreased parasympathetic to ne and increased sympathetic tone at the late phase of endoscopic proc edure. Our results indicate that gastrointestinal endoscopy induced an autonomic nervous abnormality, which may contribute to the occurrence of cardiac events during endoscopic procedures.