Effects of Enflurane on Pulse Transit Time / 대한마취과학회지

BACKGROUND: In Anesthetic state, many hemodynamic parameters including blood pressure, heart rate and arterial compliance are changed. Moreover pulse transit time (PTT) is influenced by heart rate, blood pressure changes, and the compliance of the arteries. METHODS: In this study, we investigated PTT changes in patients under enflurane anesthesia. PTT of the finger was measured by photoplethysmography (PPG) and electrocardiography (ECG). PTT values were calculated as the time interval between the peak of the ECG R wave and the peak of the second derivatived of the PPG in the finger tip. RESULTS: ECG amplitude and heart rate increased reflecting hemodynamic chnages after enflurane anesthesia, and the PTT increased after enflurane anesthesia treatment by 16.68 ms (n = 24). Moreover, PTT was found to be inversely proportion to aging. CONCLUSIONS: The increase of PTT in the finger due to relaxation of the arterial wall muscle after enflurane anesthesia was used as an indicator of sympathetic block on muscle tone. This result suggests that PTT is strongly related with anesthetic state. And PTT may be one of useful surrogative methods for anesthetic monitoring, but PTT is unfortunately only qualitative.

Thoracic Epidural Analgesia with 0.2% or 0.5% Bupivacaine during Upper Abdominal Operations / 대한마취과학회지

BACKGROUND: Thoracic epidural block has been widely used to control postoperative pain. The relative effects of the mass, volume, and concentration of local anesthetic solutions used are still subjects of debate, and the relationship between general anesthesia and thoracic epidural block is unclear. METHODS: In study I, 20 conscious patients scheduled for elective upper abdominal surgery received 0.2% bupivacaine with morphine 3 mg (group CL: n = 10) or 0.5% bupivacaine with morphine 3 mg (group CH: n = 10) via an epidural catheter inserted at the T8-T9 epidural space. The width of sensory block, blood pressure and heart rate were assessed for 30 minutes and then general anesthesia was administered. In study II, under general anesthesia, 72 patients scheduled for elective upper abdominal surgery were injected with the same formula as used in study I (group UL: n = 36, group UH: n = 36). Blood pressure, heart rate, vol% of end-tidal inhalation agent were measured for an hour. Postoperatevely, the VAS scores of both study groups were assessed in the recovery room, after 24 hours and 48 hours. RESULTS: In study I, the mean arterial pressures were significantly lower in the CH group than the CL group (P = 0.0419 and P = 0.0328 at 20 and 25 minutes after local anesthetic infusion), but heart rate and VAS score were not significantly different. In study II, no difference was observed between the groups in terms of blood pressure, heart rate, enflurane requirement, or VAS score. But hypotension requiring treatment was more frequent in the UH group than in the UL group (group UL: n = 3, group UH: n = 6). CONCLUSIONS: Epidural administration of the same volume of 0.2% bupivacaine or 0.5% bupivacaine provided similar pain relief and hemodynamic change, but profound hypotension was more frequent in the 0.5% bupivacaine group during general anesthesia. This study shows no benefit of using 0.5% bupivacaine to improve postoperative analgesia in upper abdominal surgery.