The goal of this clinical trial is to determine the ED50 and ED95 of prophylactic norepinephrine infusion for preventing post-induction hypotension in elderly patients undergoing major abdominal surgery using up-and-down sequential method . The main question it aims to answer is: What is the effective concentration of prophylactic norepinephrine infusion for preventing post-induction hypotension in elderly patients. Participants will receive different concentrations of norepinephrine infusion at the beginning of anesthesia induction until 15 minutes after intubation.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
PREVENTION
Masking
NONE
Enrollment
40
The treatment group will receive a continuous infusion of norepinephrine at the beginning of anesthesia induction until 15 minutes after intubation. The dosage of norepinephrine was decided by the up-and-down sequential allocation method with an initial dose of 0.05 µg/kg/min and a 0.005 µg/kg/min gradient.
The Second Affiliated Hospital of Zhejiang University Medical College
Hangzhou, Zhejiang, China
RECRUITINGIncidence of hypotension
less than 80% baseline blood pressure less than 80% baseline blood pressure less than 80% baseline blood pressure
Time frame: 15 minutes after intubation
incidence of bradycardia
heart rate less than 50 beat per minute
Time frame: 15 minutes after intubation
incidence of reactive hypertension
increased mean arterial pressure by \> 20% of the baseline reading
Time frame: 15 minutes after intubation
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