Respiratory Rate After Cesarean Delivery

Respiratory monitoring device will be used to count respiratory rate continuously, as opposed to the intermittent nursing respiratory rate (RR) counts once per hour. The device counts respiration (RR) using a sticker placed by on the neck to detect vibrations made by respiration. This overcomes the specific limitation of capnography that requires wearing the nasal cannula.

Prospective, observational study with institutional review board (IRB) approval. Women who undergo elective cesarean delivery under neuraxial block receive neuraxial opioids for postoperative analgesia.

Potential study recruits will be approached prior to the cesarean delivery anesthesia assessment. Suitable women will be informed that neuraxial morphine is the gold-standard analgesia, however many women suffer nausea, vomiting and pruritus (itching) and may prefer an alternative analgesic or a lower dose of morphine. All women will receive intrathecal fentanyl as an adjuvant to the bupivacaine anesthesia. This fentanyl may also cause pruritus however this is limited to the 2-hour duration of the effect of the fentanyl.

Women will be offered standard neuraxial anesthesia for cesarean delivery (heavy bupivacaine 10 mg; fentanyl 10-25mic; and low dose intrathecal morphine mic). Alternatively, women will be offered an alternative anesthesia option: 1) heavy bupivacaine 10 mg; fentanyl 10-15 mic with an ultra-low dose, 50 mic of morphine, or 2) heavy bupivacaine 10 mg; fentanyl 10-25 mic without intrathecal morphine + postoperative bilateral quadratus lumborum block (QLB), transversus abdominis plane (TAP) or erector spinus block (ESP). For patients who select block without intrathecal morphine, the choice of block will depend on anesthesiologist's decision.

Inclusion criteria

• American Society of Anesthesiologists physical status class II or III
• age between 18 and 50
• gestational age greater than 37 completed weeks
• singleton pregnancy. In contrast to previous studies
• we do not plan to exclude obese women and those with suspected sleep apnea.

Exclusion criteria

• Contraindication for epidural analgesia (bleeding diathesis, neuropathy, severe scoliosis, previous spine surgery, local anesthetic allergy)
• narcotic administration in the previous 2 hours
• inability to adequately understand the consent form
• moderate-severe asthma, inability to receive morphine
• sensitivity to sticker
• skin conditions.