Chloroprocaine Lavage to Improve Outcomes Related to Operative Cesarean Delivery

The long term objective is to show that intraperitoneal chloroprocaine can be used an alternative option to avoid general anesthesia during cesarean delivery, to alleviate mother's discomfort from surgical pain, reduce complications, and improve the birth experience. The objectives in this study are to determine the amount of chloroprocaine that is absorbed into the blood in order to create a plasma concentration time profile and to determine the incidence of side effects to help guide selection of an appropriate concentration for future study.

Compared to general anesthesia, neuraxial anesthesia (spinals and epidurals) is associated with a lower risk for maternal aspiration and airway compromise, exposes the baby to less anesthetic, and allows for greater maternal involvement in the birth process. For these reasons, it has become the preferred method of anesthesia for cesarean delivery. Spinals that are placed to facilitate cesarean delivery have a duration of one to two hours. Currently, if that duration is exceeded patients must have general endotracheal anesthesia. In addition, suboptimal neuraxial anesthesia for cesarean delivery is not uncommon with an incidence of 2-9%, depending upon the urgency of surgery and the type of neuraxial block. Providing less than adequate anesthesia for cesarean delivery may increase the risk of legal liability. For this reason, some patients with suboptimal neuraxial anesthesia have intraoperative conversion to general endotracheal anesthesia.

The first known description of the use of intraperitoneal local anesthetic to provide anesthesia for cesarean delivery was published in 1975. In this article Ranney et al. described how to use up to 100 mL of 1% procaine to provide anesthesia for cesarean delivery under local field block alone. Some of this was injected into the skin and fascia, and the remainder was diluted to 0.5% and "spilled" into the peritoneum.

Multiple publications have shown that intraperitoneal local anesthetic can be used to treat intraoperative and postoperative pain, prevent postoperative nausea, and shorten hospital length of stay. A recently published 40-month case series showed that chloroprocaine lavage can be used as part of a multimodal approach to treating intraoperative pain. In this case series, the technique of chloroprocaine lavage helped investigators to avoid general endotracheal anesthesia in 32 women having a cesarean delivery.

In this case series, no patients exhibited clinical signs of systemic local anesthetic toxicity. It is believed that chloroprocaine has a limited potential for toxicity because of its short plasma half-life, which is only 11-21 seconds. The purpose of this study is to determine the amount of chloroprocaine that is taken up into the blood stream after intraperitoneal administration to ensure that blood levels are low and do not raise a safety concern. Data obtained from this study will help to define a safe dose of chloroprocaine for intraperitoneal administration.

Eligibility Criteria:
Inclusion Criteria:

* Subjects ≥ 18 to 50 years of age having scheduled cesarean sections on 12C (Labor and Delivery) within Oregon Health \& Science University (OHSU).
* Only subjects having spinal anesthesia will be eligible.
* Only subjects that can have a Pfannenstiel incision will be enrolled.

Exclusion Criteria:

* Subjects with chronic narcotic usage
* Subjects that are deemed to need a combined spinal epidural for any reason.
* Subjects who are unable to successfully get a spinal block
* Subjects with known atypical cholinesterase activity
* American Society of Anesthesiologist physical status IV or higher
* Subjects with contraindication to neuraxial anesthesia (coagulopathy, infection)
* Subjects with stage 4 chronic kidney disease or worse (eGFR \< 30 ml/min)
* Subjects with significant hepatic dysfunction (AST or ALT \> 2x the upper limit of normal)
* Subjects with allergies to drugs required for this protocol.
* Subjects with multifetal gestations
* Subjects with a BMI \> 40 kg/m2