Please select the eligibility criteria that correspond to the clinical trial below.
Title: IRB-HSR# 14583: Intravenous Ondansetron to Attenuate the Hypotensive, Bradycardic Response to Spinal Anesthesia in Healthy Parturients
Brief Summary: The investigators hypothesize that given prophylactically, intravenous ondansetron will attenuate the drop in blood pressure and heart rate frequently seen after spinal anesthesia.

Eighty-six American Society of Anesthesiologists (ASA) physical status I or II in preoperative patient assessment, parturients age of 18 to 45 years scheduled to undergo elective caesarean section will be enrolled.

Patients will be randomized to 2 groups: the ondansetron group, receiving 8 mg intravenous ondansetron diluted in 10 mL of saline; or the placebo group, who were administered 10 mL of saline given 5 minutes prior to performing the spinal anesthetic. Investigational Pharmacy will randomize and dispense study drug.

Baseline measurements of vital signs will be taken. Otherwise standard management will then be used:

* Patients must be NPO for 8 hours
* Pulse oximetry, EKG monitoring, noninvasive blood pressure at a minimum of every 3 minutes, more frequently if decided by the provider.
* Standard lumbar puncture in a sitting position the L3-L4 or L4-L5
* Whitacre pencil-point, 25 gauge
* Injectate: 2 mL of 0.75% hyperbaric bupivacaine, 100 mcg preservative free morphine, 20 mcg fentanyl
* Immediately after completing the subarachnoid injection, patients will be laid supine with left lateral uterine displacement

The sensory level of anesthesia will be assessed in the standard fashion every five minutes using ice. The motor component will tested using the Bromage scale for spinal anesthesia (0, no paralysis; 1, inability to lift the thigh \[only knee/feet\]; 2, inability to flex the knee \[only feet\]; 3, inability to move any joint in the legs).


Options:
A: Inclusion criteria:

* Ability to speak and understand English
* Term (37-42 weeks' gestation)
* Cephalic presentation
* Singleton pregnancy
* ASA 3 or less
* No pregnancy-induced hypertension
* No chronic hypertension
* BMI \<40
* No evidence of pre-epidural fetal heart rate abnormality
* No IUGR or low AFI. ASA 1-3 women who request epidural analgesia Informed consent signed upon admission to L\&D

Exclusion Criteria:

* ASA 4 women, BMI \> 39
* Contraindication to epidural analgesia
* Twin pregnancy
* Preterm labor
* Severe preeclampsia
* Decision to perform CS prior to epidural insertion
* Unable to read or speak English
* Unable or unwilling to sign the IFC
B: Inclusion Criteria:

* Patients 18 years or older, presenting for scheduled cesarean delivery to the C7 birthing centre.

Exclusion Criteria:

* Unable to communicate in English or French
* Multiple gestations
* Patients with hypertension
* Patients with contraindications to any drug or techniques used in the study
* BMI \> 35
C: Inclusion Criteria:

* elective cesarean section applying spinal anesthesia
* ≥ week 37 of gestation
* Singleton pregnancy

Exclusion Criteria:

* Suspicion of any hypertensive disease
* Parturient in labor
D: Inclusion Criteria:

* Elective Caesarean section
* Consent to be in the study
* Age 18-45
* ASA 1 or 2

Exclusion Criteria:

* Patient refusal
* Patients with known allergy to ondansetron will be excluded
* Contraindications to spinal anesthetic

  * Known Coagulopathy (acquired e.g. anticoagulation or existing such as liver disease; using patient history, physical examination to determine bleeding risks, a platelet count under 100 or a PT INR over 1.4)
  * Severely altered anatomy (e.g. post surgical changes)
  * Existing neurological deficits (Women with a history of migraine or tension headache will be allowed to enroll. More severe conditions with daily life limiting symptoms will be excluded. Examples include epilepsy, pseudotumor cerebri, prior stroke with persistent neurologic deficits, or any motor or sensory neuropathy with existing deficits)
  * Skin infection overlying site

Answer: D