This study aims to evaluate the efficacy of hyperbaric 5 mg bupivacaine + fentanyl 25 mcg versus hyperbaric 7.5 mg bupivacaine + fentanyl 25 mcg to lower incidence of hypotension

Approval from Ethical Committee of Faculty of Medicine Universitas Indonesia was acquired prior conducting the study. Subjects will be recruited using consecutive sampling method. Sample size was determined using alpha 5%, power 80%, and the difference of the incidence of hypotension 20%. The sample of each group is 56 patients. The investigators will use ECG, blood pressure monitoring, and pulse oxymetry for the standard monitoring. Patients will be given oxygen 3 L/minute via nasal cannula. Before the spinal anesthesia, patients will be given co-loading 500 ml of Ringer Lactate. Patients will be in sitting position while the lumbal puncture is conducted using 27G Quincke in the level of L3-4 or L4-5 or Tuffier's line. After ensuring that the tip of the needle is in the subarachnoid space, the drug will be administered with the speed of 0.2 mL/s. All the procedure will be conducted in sterile condition. Patients will receive ketoprofen suppositoria as the postoperative analgesia and can be discharged to the ward when the Aldrete's score is more than 8.

The onset of sensoric blockade is assessed using pinprick test until the level of T6 or maximum until 20 minute. The peak value will be recorded. The motor blockade will be assessed using the Bromage scale. Incision will be done when the level of sensory block reached T6. If patients report pain after delivery of the baby, intravenous fentanyl 0,67-1 mcg/kg will be given twice with the interval of 10 minutes. If pain persists, conversion to general anesthesia will be conducted.

The measurement of blood pressure, heart rate, respiratory rate, temperature, and O2 saturation will be recorded during the minute of 3, 6, 9, 12, 15, 20, 30, 40, 50, and 60 after the spinal anesthesia is administered or until the baby is delivered. Patients will be recorded as hypotensive when she experienced reduction of blood pressure more than 30% from baseline or systolic pressure less than 100 mmHg from the moment the spinal anesthesia is administered until the baby is delivered. If the systolic pressure is less than 90 mmHg, patient will be given ephedrine 5 mg iv that is repeated every minute until the systolic pressure is over 90 mmHg.

The duration of the surgery is also recorded. Nausea, vomiting, syncope, dizziness, chest discomfort, and other intraoperative complaint will be recorded. Postoperative nausea and vomiting, itching, shivering, back pain, Post Dural Puncture Headache (PDPH), and Transient Neurologic Symptoms (TNS) will also be recorded.

Inclusion Criteria:

• pregnant women with ASA PS 1-3
• age 18-40 years old
• in an elective or emergency cesarean delivery using spinal anesthesia

Exclusion Criteria:

• patients with contraindication of spinal anesthesia
• have history of allergy to bupivacaine or fentanyl
• with eclampsia
• valvular heart disease
• congenital heart disease
• coronary heart disease
• twin pregnancy
• morbid obesity (BMI >=40)
• pre-partum hemorrhage with hemodynamic instability

Pregnant women

Simple randomization will be conducted using a software by one of the researchers (HA) into two groups with equal size. To ensure the concealment, the randomization list will be kept in a sealed enveloped and opened by the physician who administered the spinal anesthesia just before the surgery. Data recording will be conducted by independent observers. This is a double-blinded study for the subjects and for the observers. The enrollment of the participants will be conducted by HA. Patients will not be notified about the dose scheme. Physician who performed the spinal anesthesia are different from the observers. Observers are junior residents trained to test the spinal adequacy and to perform monitoring in spinal anesthesia. It us not possible to blind the physicians who perform the spinal anesthesia because they will notice the volume difference.