Evaluation of the Typical Spinal Block During Cesarean Delivery

Primary Objective:

• Evaluate the accuracy of sensory testing with blunt plastic 16-gauge cannula during the 15 minutes after spinal injection for predicting spinal failure. Cephalad sensory dermatomal levels will be assessed at 1 (t1), 3 (t3), 5 (t5), 7 (t7), 9 (t9), 11 (t11), 13 (t13), and 15 (t15) minutes after intrathecal 1.6 ml 0.75% bupivacaine in 8.25% dextrose combined with 15 mcg fentanyl and 150 mcg morphine (study solution). Spinal failure, which is defined as inability to achieve a T4 level to pinprick by the 15-minute timepoint or intraoperative pain (VAS > 0) requiring treatment

Secondary Objectives:

• Conversion to another anesthetic technique (general anesthesia or activation of the epidural catheter)
• Inadequate anesthesia (analgesic supplementation with ketamine, > 20 mg propofol, > 2 mg midazolam, > 10 mg parental morphine equivalents, or intraperitoneal chloroprocaine).
• Patient satisfaction upon arrival to the postanesthesia care unit, rated on a 1-5 Likert scale

A sample size calculation

Population: 250 pregnant females undergoing non-emergency cesarean section delivery in the Labor & Delivery Operating Rooms at Oregon Health & Science University.

Number of Sites: Single center trial

Study Duration: Institutional Review Board approval has been obtained. Study initiation, enrollment, and data collection is expected to take 24 months. Data analysis, manuscript writing, editing, submission and revision to a peer-reviewed journal is expected to take an additional 6 months.

In summary, the study should be completed in under 3 years.

Subject Participation Duration: Total time of subject participation including time for recruitment, enrollment, data collection during the preanesthesia consult, and post-consult data collection will be less than 3 hours.

Estimated Time to Complete Enrollment: Estimated time from enrollment into study of the first subject to enrollment into study of the last subject is 24 months.

Inclusion criteria

• Patients undergoing cesarean delivery under spinal or combined spinal epidural anesthesia
• BMI between 20 and 40 kg/m2
• Height between 5 feet 2 inches and 5 feet 10 inches.
• English and non-English speaking patients, if interpretive services are available

Exclusion criteria

• Patient refusal
• Contraindications to neuraxial anesthesia (coagulopathy, CNS pathology, infection at site of needle puncture)
• Allergy to any study medications
• Use of epidural anesthesia
• Emergency (red) cesarean delivery
• Conditions that impact dermatomal sensory testing including spinal cord injury with sensory deficits and abdominoplasty
• Prison inmates
• Decisionally impaired individuals
• Pregnancies involving multiple fetuses