Intracutaneous Sterile Water Injections
Intracutaneous Sterile Water Injections
For most women, the most significant pain they will experience is the pain associated with
 childbirth. Up to one-third of women experience "back labor", this typically occurs when the
 fetus assumes varying degrees of malposition, especially the occiput posterior position, and
 causes additional constant pressure against the maternal spine and pelvis. "Back labor"
 presents as constant pain, that occurs even between contractions. It is often difficult to
 manage, by the patient, the obstetrician, and the anesthesiologist, and may increase the rate
 of instrumental and caesarian delivery.

 Epidural anesthesia/analgesia is the most common and effective intervention used to help
 women cope with labor pain. Dilute concentrations of local anesthetic and opioid provide
 complete analgesia for most women. Some women, however, have breakthrough pain, often due to
 "back labor," and require more concentrated drug solutions. This increases the side effects
 associated with these drugs (e.g., hypotension, pruritus, motor block), thus treatment of
 this pain poses a challenge for the anesthesiologist and the obstetrician.

 Sterile water injections (SWI) are a simple and well-established method of managing labor
 pain among midwives. This intervention was first used to alleviate pain associated with
 kidney stones, and was introduced to obstetrics in the 1970s. Using a syringe, small amounts
 of sterile water is deposited subcutaneously near the sacral area. The sterile water causes
 osmotic and mechanical irritation resulting in a brief (15-30 second) and significant
 stinging sensation. The onset of pain relief follows almost immediately and may last for up
 to two hours. The procedure can be repeated a number of times.

 Sterile water for pain management is most often administered using four intracutaneous
 injections: two sites lateral to the lumbosacral spine and two sites 2-3 cm below and 1-2 cm
 medial to the original two injection sites. 0.1 mL of sterile water is injected between the
 dermal layers to raise a small bleb on the skin surface at each of the four sites. In labor,
 the injections are administered sequentially during a uterine contraction, with the series of
 four injections, performed two at a time, completed within 20-30 seconds.

 The investigators hypothesize that the use of sterile water injections in women with
 neuraxial analgesia with breakthrough pain will result in decreased local anesthetic
 requirements and increase patient satisfaction.
Since it is assumed that the neuraxial anesthetic is placed prior to transition to active
 phase of labor, the patient will receive the intervention when they report breakthrough pain.
 Prior to administration of the intervention, the adequacy of the existing neuraxial
 anesthetic will be verified as bilateral decreased discrimination to cold from T8 to the
 sacrum. Four tuberculin syringes, each containing 0.1 mL of the assigned solution labeled
 "study drug" will be prepared. Patients allocated to the study group will receive sterile
 water, and those allocated to the control group will receive sterile normal saline solution.

 The area to be injected will be prepared with chlorhexidine wipes to ensure sterility. In the
 sitting position, study subjects will receive a total of 0.4 mL of "study drug" via four
 injections: bilateral injections at the posterior superior iliac spine on and bilateral
 injections at 1 cm medial and 1-2 cm inferior to the first point.

 Patients will be asked to rate their overall labor pain using a 0-100 mm visual analog scale
 (VAS) for pain prior to study drug administration and every 30 minutes until commencement of
 pushing. They will also be asked to specifically rate low back pain with the VAS. Analgesia
 administration data from the time of study drug injection, including maintenance epidural
 solution volume, time of first patient controlled epidural analgesia (PCEA) bolus request,
 number of PCEA bolus requests and delivered doses, total PCEA bupivacaine dose, time to first
 request for manual rebolus, number of manual bolus doses, manual bolus bupivacaine dose,
 total bupivacaine dose and total fentanyl dose.

 Additional recorded data will include maternal age, height, weight, cervical dilation at
 initiation of neuraxial analgesia and at study drug administration, duration of labor
 (initiation of analgesia to delivery), maximum oxytocin infusion rate during labor, and mode
 of delivery. A "total labor pain score" will be assessed approximately 60 minute after
 delivery, as well as satisfaction with labor analgesia using a 100-mm VAS.
Inclusion Criteria:

 -  multiparous women

 -  spontaneous labor

 -  at least 18 years of age

 -  presenting for vaginal delivery with cervical dilation of 4 centimeters or less

 Exclusion Criteria:

 -  nulliparous

 -  less than 18 years old

 -  contraindication to placement of neuraxial anesthetic

 -  skin infection in area to be injected

 -  medical therapies considered to result in tolerance to opioids

 -  history of chronic pain (requiring regular medical follow-up with pain specialists)

 -  recent use of opioid analgesics (within the year preceding pregnancy)