2.2. Study Protocol and Intervention
hypotension
After all the eligible parturients entered the operating room, venous passage of the upper limb was established, and the left radial artery catheterization was performed under local anesthesia, and BP, HR, EKG and SpOAfter intrathecal injection of 10 min, the maternal sensory block level was measured by acupuncture method. If the level did not reach T6, 2% lidocaine 5–10 ml was injected through the epidural catheter and exclude the case; if T6 was reached or exceeded, the operation would be started. BP and HR were recorded every minute from immediately after intrathecal injection to 20 minutes after spinal anesthesia. If the maternal SBP decreased by more than 20% or less than 90 mmHg at a single time, it was defined as hypotension and 5 