Clinical trial NCT01843517: Endogenous Pain Facilitation and Inhibition in Postpartum Women
Official title: Endogenous Pain Facilitation and Inhibition in Postpartum Women
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Pain Inhibition and Facilitation in Post Partum Women
Keywords: Pain
Facilitation
Inhibition
Oxytocin
Postpartum
Lead sponsor: Wake Forest University Health Sciences
Sponsor class: OTHER
First posted: 2013-04-30
Enrollment: 80
Sex: FEMALE
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: Healthy women 10-14 days postpartum following term vaginal delivery, who are breast feeding and age- and race- matched healthy, nonpregnant women, either nulliparous or at least 1 year beyond delivery.

Brief summary: This study seeks to further understand these three observations - (1) that the time period surrounding childbirth accelerates recovery from pain after injury (2) that this likely reflects dampened facilitating mechanisms and exaggerated inhibitory mechanisms, and (3) that stress may interfere with this protection. In this study the investigators will compare women within 2 weeks of delivery to age matched controls and anticipate that pain inhibition is increased after delivery, pain facilitation is decreased, and that there is a relationship between these pain responses and the degree of pre-existing stress.

Detailed description: Nearly half of the world's population experiences labor and delivery processes which are associated with microscopic or gross tissue injury to the mother. Since this experience is widespread and occurs relatively early in life, the psychosocial, medical, and financial consequences of chronic pain following childbirth could be enormous. Surprisingly, previous studies with long term follow up of new mothers have included pain as a secondary measure and / or have focused on prevalence of pain without determining whether pain predated delivery or even pregnancy itself. The investigators recently performed a long term follow up study of over 1,200 women, and noted that pain which began during the childbirth itself was surprisingly rare in comparison to other physical injuries. Additionally, two central factors hypothesized to confer risk of chronic pain after other injuries including surgery, pre-dating chronic pain and degree of tissue and nerve injury, contributed minimally to the acute and sub-acute pain after childbirth. These two observations, low incidence of chronic pain and minimal effect of degree of tissue injury and history of chronic pain on sub-acute pain, point towards a potential protective effect of pregnancy or delivery on the response to physical injury.

Eligibility criteria: Inclusion Criteria:

* female
* 10-14 days postpartum, term vaginal delivery
* breastfeeding (postpartum women)
* health non-pregnant female (nulliparous or at least 1 year beyond delivery)

Exclusion Criteria:

* Allergy to chili peppers
* pregnant
* pain medication (narcotic or non-narcotic) within 4 hours of study visit Average pain in the 24 hours preceding the study visit \>3. Postpartum women that score \>13 on the Edinburgh Postnatal Depression Scale

Primary outcomes:
measure: Area of hyperalgesia will be the primary outcome measure
timeFrame: 40 minutes post capsaicin application
measure: Percent reduction in degree of pain to the 49 degrees Celsius stimulus during the time the foot is immersed in the cold water
timeFrame: 15 minutes
Secondary outcomes:
Other outcomes:
Locations:
city: Winston-Salem
country: United States
facility: Wake Forest Baptist Medical Center
state: North Carolina
Study officials:
affiliation: Wake Forest University Health Sciences
name: James C. Eisenach, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Pan PH, Tonidandel AM, Aschenbrenner CA, Houle TT, Harris LC, Eisenach JC. Predicting acute pain after cesarean delivery using three simple questions. Anesthesiology. 2013 May;118(5):1170-9. doi: 10.1097/ALN.0b013e31828e156f.
citation: Street LM, Harris L, Curry RS, Eisenach JC. Capsaicin-induced pain and sensitisation in the postpartum period. Br J Anaesth. 2019 Jan;122(1):103-110. doi: 10.1016/j.bja.2018.09.026. Epub 2018 Nov 16.