Changes in Cardiac Output During Cesarean Delivery Under Spinal Anesthesia

Study Overview
=================
Brief Summary
-----------------
Cardiac output will be measured in healthy parturients undergoing cesarean delivery under spinal anesthesia

Detailed Description
-----------------
ASA-II women undergoing cesarean delivery under spinal anesthesia will be included. Cardiac output will be measured using transthoracic echocardiography at 4 time points: Baseline, after 10 minutes of intrathecal injection, after delivery, and after 1 hour of intrathecal injection. Spinal anesthesia will be administered with 2.5 ml bupivacaine 0.5% and fentanyl 15 μg.

Official Title
-----------------
Changes in Cardiac Output During Cesarean Delivery Under Spinal Anesthesia. A Prospective Observational Study Using Transthoracic Echocardiography

Conditions
-----------------
Anesthesia, Spinal, Cesarean Section, Echocardiography, Cardiac Output

Intervention / Treatment
-----------------
* Radiation: Transthoracic Echocardiography
* Procedure: Spinal Anesthesia
* Drug: Intrathecal Bupivacaine
* Drug: Intrathecal Fentanyl
* Drug: Crystalloid Coload 1000 mL
* Procedure: Cesarean Delivery
* Drug: Intravenous Ephedrine
* Drug: Oxytocin


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: American Society of Anesthesiologists physical status II parturients. Full term, singleton pregnancy Elective cesarean delivery under spinal anesthesia Exclusion Criteria: Height <150 cm Weight <60 kg Body mass index (BMI) <18.5 or ≥ 35 kg/m² Women presenting in labor Contraindications to spinal anesthesia: increased intracranial pressure, coagulopathy, or local skin infection Hemoglobin <10 g/dL Current administration of vasoactive drugs (e.g., salbutamol, thyroxin) Diabetes mellitus, cardiovascular, or renal disease Chronic or pregnancy-induced hypertension Polyhydramnios Women with high risk for postpartum hemorrhage or uterine atony (e.g., placenta accreta spectrum, ≥3 previous cesarean deliveries)

Ages Eligible for Study
-----------------
Minimum Age: 19 Years
Maximum Age: 40 Years

Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Study Group<br>Cardiac output will be measured at baseline using transthoracic echocardiography. Spinal anesthesia will be administered with injection of intrathecal bupivacaine and intrathecal fentanyl. Crystalloid coload 1000 mL will be administered: Ringer acetate 1000 mL will be administered over 10 minutes starting immediately after intrathecal injection. Cardiac output will be measured at 10 minutes after intrathecal injection, immediately after delivery, at 1 hour after intrathecal injection. Cesarean delivery will be performed. Intravenous ephedrine will be administered to correct hypotension. After delivery, 10 units of oxytocin in 500 ml Ringer acetate will be administered over 30 minutes. | Radiation: Transthoracic Echocardiography<br>* Measurement of cardiac output in supine position with left lateral tilt at baseline, at 10 minutes after intrathecal injection, immediately after delivery, and at 1 hour after intrathecal injection<br>Procedure: Spinal Anesthesia<br>* Performed at the L3-L4 or L4-L5 interspace using 25-gauge spinal needle<br>Drug: Intrathecal Bupivacaine<br>* Bupivacaine 12.5 mg (2.5 mL 0.5%) will be administered in the subarachnoid space<br>Drug: Intrathecal Fentanyl<br>* Fentanyl 15 μg will be administered in the subarachnoid space<br>Drug: Crystalloid Coload 1000 mL<br>* Ringer acetate 1000 mL will be administered over 10 minutes starting immediately after intrathecal injection<br>Procedure: Cesarean Delivery<br>* Lower segment cesarean section using the Pfannenstiel incision and uterine exteriorization<br>Drug: Intravenous Ephedrine<br>* Intravenous ephedrine 3, 5, and 10 mg will be administered when Systolic blood pressure decreases below 90%, 80%, and 70% of baseline, respectively.<br>Drug: Oxytocin<br>* Intravenous oxytocin 10 U in 500 mL Ringer acetate will be administered over 30 minutes starting immediately after delivery of the fetus<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in cardiac output | Cardiac output measured using transthoracic echocardiography | At baseline, at 10 minutes after intrathecal injection, immediately after delivery, and at 1 hour after intrathecal injection | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in stroke volume |  | At baseline, at 10 minutes after intrathecal injection, immediately after delivery, and at 1 hour after intrathecal injection | 
| Changes in heart rate |  | At baseline, at 10 minutes after intrathecal injection, immediately after delivery, and at 1 hour after intrathecal injection | 
| Number of subjects requiring ephedrine |  | From intrathecal injection to the end of cesarean delivery | 
| Incidence of hypotension | Systolic blood pressure <80% of baseline | From intrathecal injection to the end of cesarean delivery | 
| Incidence of severe hypotension | Systolic blood pressure <70% of baseline | From intrathecal injection to the end of cesarean delivery | 
| Incidence of bradycardia | Heart rate <50 beats/min | From intrathecal injection to the end of cesarean delivery | 
| Incidence of nausea and/or vomiting |  | From intrathecal injection to the end of cesarean delivery | 
| Neonatal Apgar scores |  | At 1 and 5 minutes after delivery |