Comparing Bupivacaine, Lidocaine, and a Combination of Bupivacaine and Lidocaine for Labor Epidural Activation

The most common and effective method for controlling labor pains is a local anesthetic (LA) infusion through a lumbar epidural. To achieve adequate pain control during the first stage of labor - onset of contractions to complete cervical dilation - nerve fibers up to the T10 dermatome must be anesthetized. When a patient is in active labor and an epidural catheter is placed, the anesthesiologist must activate the epidural by administering LA through the epidural to promote spread of the LA in the epidural space to anesthetize the nerve fibers involved in the conduction of labor pains. The ideal LA to achieve this goal is one that would allow for the fastest onset to achieve quick pain relief with the fewest side effects.

Two commonly used LA to provide labor analgesia are bupivacaine and lidocaine. When low concentrations - 0.25% bupivacaine and 1% lidocaine - are used for labor analgesia, both of these LA can be administered safely with very little concern of major adverse effects associated with LA toxicity. Given that there is limited and conflicting evidence for the usefulness of the bupivacaine and lidocaine mixture especially as it relates to labor epidural activation, we hope to readdress these questions in an effort to determine whether or not the LA combination offers any distinct advantage over the individual LA. The investigators intend to determine the time it takes to achieve an adequate level (T10) for labor analgesia, the total spread of local anesthetic, and the degree of motor block as these factors will be important in determining the most optimal LA solution to activate a labor epidural. With the results from this study, the investigators hope to recommend a LA solution that will allow for the fastest pain relief in the laboring mother with the fewest side effects.

• 1% Lidocaine (Drug), also known as Lidoderm, Xylocaine, Recticare, Anecream,, Solarcaine, Anestacon, Cutiecaine, Lidocoll,: 10 mL of 1% lidocaine
• 0.25% Bupivacaine (Drug), also known as Marcaine and Sensorcaine: 10 mL of 0.25% bupivacaine
• Bupivacaine plus Lidocaine (Drug), also known as Lidoderm, Xylocaine, Recticare, Anecream, Lmx4, Akten,, Marcaine and Sensorcaine: 5 mL of 1% lidocaine and 5 mL of 0.25% bupivacaine

Primary outcomes

• Time to Achieve an Adequate Epidural Level for Labor Analgesia [Baseline to 1 hour]: time it takes to achieve a T10 dermatome level by pinprick. A T10 dermatome level is what is needed to control labor pain.

Secondary outcomes

• Number of Patients Who Achieve Adequate Analgesia [Baseline to 1 hour]: The number of patients who received an adequate epidural level of T10 or higher
• Degree of Motor Block [Baseline to 1 hour]: degree of motor block which means the amount of weakness in the legs experienced by the participants. this was determined by using the Bromage scale where 4 = greatest amount of motor block or muscle weakness and 0 = the least amount of motor block.
• Number of Patients Who Experienced of Maternal Hypotension [Baseline to 1 hour]: Number of patients who experienced maternal hypotension defined as a blood pressure (BP) >20% decline from baseline and need for vasopressor therapy

Sex: Female, ages: 19 Years to 60 Years, accepts healthy volunteers

Inclusion Criteria:

* Pregnant patients over the age of 19 who are scheduled for an induction of labor and request an epidural are eligible for the study

Exclusion Criteria:

* age <19
* allergy to the drug or drug class
* preexisting neuropathy
* history of back pain prior to pregnancy or history of back surgery
* history of chronic opioid use
* history of hypertension or hypertensive disorders of pregnancy
* congenital or acquired cardiac disease
* contraindication to epidural placement (patient refusal, severe coagulopathy, infection at site of epidural needle insertion, severe hypovolemia)

Participant flow

Outcome results

• Time to Achieve an Adequate Epidural Level for Labor Analgesia (Primary), Mean, minutes: 1% Lidocaine 7.0 +/- 3.9; 0.25% Bupivacaine 11.0 +/- 5.8; Bupivacaine Plus Lidocaine 8.5 +/- 4.6
• Number of Patients Who Achieve Adequate Analgesia (Secondary), Count of participants, Participants: 1% Lidocaine 23; 0.25% Bupivacaine 25; Bupivacaine Plus Lidocaine 23
• Degree of Motor Block (Secondary), Mean, Bromage Score: 1% Lidocaine 2.0 +/- 0.6; 0.25% Bupivacaine 1.7 +/- 1.0; Bupivacaine Plus Lidocaine 1.9 +/- 0.9
• Number of Patients Who Experienced of Maternal Hypotension (Secondary), Count of participants, Participants: 1% Lidocaine 4; 0.25% Bupivacaine 0; Bupivacaine Plus Lidocaine 0

Adverse events

Time frame: From start of epidural placement until 1 hour after placement.

Other adverse events by term

• Study Protocol and Statistical Analysis Plan (PDF, 2020-04-29)

• Mark F Powell, MD, Principal investigator, University of Alabama at Birmingham