Investigators want to find the concentration of epidural ropivacaine, which can block hemodynamic changes in the onset of pneumoperitoneum in the laparoscopic gastrectomy.
According to previous patient's response, the investigators will allocate the concentration of ropivacaine of next patient during Co2 insufflation. And, for this allocation of concentration of ropivacaine, the investigators use biased coin design up-and-down method. Based on the practices, the starting concentration is 0.375 %, and the step size of concentration is 0.125%.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
PREVENTION
Masking
NONE
Enrollment
50
According to previous patient's response, the investigators will allocate the concentration of ropivacaine of next patient during Co2 insufflation. And, for this allocation of concentration of ropivacaine the investigators use biased coin design up-and-down method.
Changes from baseline in heart rate (bpm) after CO2 insufflation
Heart rate will be recorded before anesthesia induction, during CO2 insufflation, after Co2 insufflation. The mean value of heart rate before anesthesia induction will be regarded as the baseline values. If maximum heart rate after Co2 insufflation increased by \>20% from baseline value, the response will be regarded as "fail" and increased concentration of ropivacaine will be applied to next patient by up and down method.
Time frame: immediately after CO2 insufflation : 1,2,3,4,5,6, 7, 8, 9, 10 minutes after CO2 insufflation
Changes from baseline in mean arterial pressure (mmHg) after CO2
Mean arterial pressure will be recorded before anesthesia induction, during CO2 insufflation, after Co2 insufflation. The mean value of mean arterial pressure before anesthesia induction will be regarded as the baseline values. If maximum mean arterial pressure after Co2 insufflation increased by \>20% from baseline value, the response will be regarded as "fail" and increased concentration of ropivacaine will be applied to next patient by up and down method.
Time frame: immediately after CO2 insufflation : 1,2,3,4,5,6, 7, 8, 9, 10 minutes after CO2 insufflation
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