Wpływ znieczulenia zewnątrzoponowego piersiowego na zmienność rytmu serca po pionizacji

Magdalena Fijałkowska, Lesya Riznyk, Krzysztof Przesmycki

Summary
Background. Heart rate variability (HRV) analysis has been used for assessment of cardiac autonomic balance that may be affected by thoracic epidural anaesthesia (TEA). The influence of TEA on cardiac autonomic balance in the horizontal position is subject to controversy. In order to clarify it, we have studied the effects of TEA on HRV before and after orthostatic stress. Methods. Thirty-four patients, scheduled for elective thoracic and abdominal procedures, were administered 5-6 ml of 0.5% bupivacaine via a thoracic epidural catheter one day before surgery. HRV was recorded in the supine position during 30 minutes before and after TEA, followed by an orthostatic stress test (rapid change from supine to standing position). Results. The spread of TEA was from Th₂ to Th₁₂ in all patients. Orthostatic stress resulted in moderate hypotension in 3 of 34 patients before institution of TEA, and in 9 after TEA (p<0.05). TEA caused a significant increase in total HRV (SD of RR intervals) and spectral domain (total power and its components) in patients remaining in the horizontal position. The orthostatic stress, performed before TEA, produced a typical sympathetic reaction, expressed as a significant increase of the ratio of low-frequency to high-frequency variabilities (LF/HF). This reaction was not observed after induction of TEA. Conclusions. In patients remaining in the horizontal position, TEA increases total HRV without changing the LF/HF index. HRV analysis during orthostatic stress confirms that TEA decreases cardiac sympathetic activity.

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