Maternal hypotension is a common side effect after spinal anesthesia for cesarean delivery.Decreased vascular resistance and cardiac output, due to sympathetic blockade1and blood pooling in blocked areas of the body respectively, are main causes of spinal anaesthesia-induced hypotension during Caesarean delivery.

Cardiac output, which has shown to be a better predictor of organ and placental perfusion than arterial blood pressure.Few studies have measured CO after spinal anesthesia in the maternal population.This is largely because of the lack of availability of accurate and reproducible noninvasive measurement techniques. Up to now, preventing hypotension has continued to focus on arterial blood pressure variables, fluid, and ephedrine requirements as markers of cardiovascular status, because these are more easily measured.

Investgators hypothesized that CO and PetCO2, in parturients with the degree of hypotension during spinal anaesthesia, would also have a positive and significant association.

Inclusion Criteria:

• full-term gestation (>36 and <41 weeks of gestation) with a singleton pregnancy

Exclusion Criteria:

• emergency cases
• placenta praevia
• preeclampsia
• cardiovascular or cerebrovascular disease
• morbid obesity with a BMI≥40
• contraindications to spinal anaesthesia

American Society of Anesthesiologists physical status I and II patients undergoing elective cesarean delivery under combined spinal-epidural (CSE) anesthesia