The value of phenylephrine administration in response to tachycardia in preventing hypotension after spinal anesthesia in elective cesarean section.

This observational study will take place at Ain Shams University Maternity hospitals, Cairo, Egypt. All patients will sign written informed consent before inclusion.

Sample size:

Using PASS 15 program for sample size calculation, setting confidence level at 95% and margin of error at 0.05, it is estimated that sample size of 80 women will be needed to detect an expected incidence rate of hypotension after phenylephrine administration of 30% "Hasanin et al., 2019"

Inclusion criteria:

ASA II pregnant female planned for elective C.S., aged between 18 -35 years old.

Exclusion criteria:

Emergency CS, Complicated CS (Severe bleeding, organ injury, uterine atony), ASA III, VI & patients with cardiovascular diseases For all pregnant females including whose in the study group, preoperative labs will be done including ( CBC, INR, Liver function & Kidney function) , oral and written informed consents will be taken from the patients with explanation of the spinal anesthesia and expected complications.

In OR wide pore IV access and preload started with crystalloids, full standard monitoring, spinal anesthesia will be performed by the expert anesthetist. The pregnant female will be in the sitting position and complete sterilization of her back, local anesthesia by 5 ml lidocaine 1% then the spinal needle (Pencil point 27 G) introduced between L4-5 and injection of (50 µg fentanyl + bupivacaine 0.5%) in total volume between 1.8 - 2.3 according to patient's height.

Then patient will lie supine with head elevated 30 degrees by a bellow and start recording the data just after spinal anesthesia.

Phenylephrine will be given in a dose of 50 µg IV immediately if the heart rate increases ≥ 20 % of baseline.

Then blood pressure & HR will be recorded after the administration of phenylephrine and every 5 minutes.

Any further doses given will be recorded.

Inclusion Criteria:

• ASA II pregnant female planned for elective C.S., aged between 18 -35 years old.

Exclusion Criteria:

• Emergency CS, Complicated CS (Severe bleeding, organ injury, uterine atony), ASA III, VI patients with cardiovascular diseases

Pregnant female at childbearing period