Endogenous Pain Facilitation and Inhibition in Postpartum Women

Completed

• Conditions: Pain Inhibition and Facilitation in Post Partum Women

• Registration Number: NCT01843517
• Lead Sponsor: Wake Forest University

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.

Study Timeline

• Study Start: 2013-04
• Study First Submitted: 2013-04-25
• Study First Submitted QC: 2013-04-25
• Study First Posted: 2013-04-30
• Status Verified: 2017-12
• Primary Completion: 2017-12-05
• Study Completion: 2017-12-05
• Last Update Submitted: 2017-12-15
• Last Update Posted: 2017-12-19

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 80

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

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Percent reduction in degree of pain to the 49 degrees Celsius stimulus during the time the foot is immersed in the cold water	15 minutes	Conditioned pain modulation will be induced by placing a foot in a container of circulating water maintained at 10 degrees Celsius for 90 seconds. Thirty seconds after the foot is placed into container of circulating water, the stimulus response to heat on the contralateral forearm will be measured using a 49 degrees Celsius stimulus for 5 seconds. The foot will then be withdrawn and warmed with warm blankets. The stimulus response to heat stimuli on the arm will be measured 5 and 15 min thereafter.
Area of hyperalgesia will be the primary outcome measure	40 minutes post capsaicin application	Hyperalgesia and allodynia on the skin of the forearm will be established by heating the forearm with a 4 cm2 Peltier controlled thermode (TSA®) to 45 degrees Celsius for 5 minutes. The investigators will then apply topical capsaicin (0.075% cream, Bioglan Pharmaceuticals) under an occlusive dressing at the same site as the thermal probe for 30 minutes. 40 minutes after removal of the capsaicin cream the site will be heated to 40 degrees Celsius for 5 minutes (rekindling) following the end of capsaicin application. The investigators will test skin sensations with the filament and cotton wisp after this heating.

Trial Locations

Locations (1)

Wake Forest Baptist Medical Center; 🇺🇸 Winston-Salem, North Carolina, United States