Effect of Intrathecal Morphine on Chronic Pain After Elective Caesarean Section
Condition: Chronic Pain Post-Procedural
MeSH terms: Chronic Pain
Study type: Interventional
Phase: Phase 4

Summary: 
      The incidence of chronic post-surgical pain (CPSP) after caesarean section (CS) is reported
      to be as high as 18%, reflecting it to be a significant clinical problem. Studies related to
      prevention of progression of acute post-CS pain to its chronicity are sparse. Current
      guidelines on post-CS analgesia recommend the use of intrathecal (IT) opioids to spinal
      anaesthesia for improved post-CS pain relief. Despite its frequent use, studies related to
      the IT morphine use and its association with post-CS chronic pain are lacking.

      A recent prospective observation study revealed a significant reduction in persistent pain
      after CS when IT morphine was used as an adjuvant to spinal anaesthesia. However, there is no
      any randomized controlled trial (RCT) that has explored this association to date. We
      hypothesized that spinal morphine would reduce the incidence of persistent pain after CS.
    

Detailed description: 
      This prospective, randomised, double-blind trial will take place at B.P Koirala Institute of
      Health Sciences, a University hospital situated in Nepal. Approval for the study has been
      obtained from the institution ethical committee. After the trial is registered, recruitment
      of the patient will be initiated. Consent for the participation in the study will be obtained
      during pre-anaesthetic assessment visits in the evening before surgery. During this visit,
      preoperative anxiety level (hospital anxiety and depression scale), pain catastrophizing
      (assessed with pain catastrophizing scale), preoperative pain sensitivity (assessed with pain
      pressure threshold and tolerance) will be recorded. The investigator will also educate the
      patients regarding the use of NRS scores for postoperative pain and satisfaction ratings.

      Patients will be randomly assigned in a 1:1 ratio to one of the two groups (morphine and
      placebo groups). Randomization will be done in variable block sizes (4/6/8) by an internet
      based random-number generator list.

      Morphine group will receive intrathecal 11 mg of hyperbaric bupivacaine (2.2 mL 0.5%), 10μg
      of fentanyl (0.2 ml) and 100 μg of preservative free morphine (0.1 ml). Placebo group will
      receive 11 mg of hyperbaric bupivacaine (2.2 mL 0.5%), 10μg of fentanyl (0.2 ml) and normal
      saline (0.1ml).

      Postoperatively, pain, opioid consumption, sedation, nausea or vomiting, pruritus, and
      respiratory depression in the postanesthesia care unit (time 0 hours) and at 2, 6, 12, 24,
      and 48 hours will be evaluated. The area of hyperalgesia around the surgical incision will be
      assessed at 48 hrs postoperatively using a von Frey filament.

      Patient satisfaction from postoperative analgesia will be assessed using a 5-point scale (1 =
      very unsatisfied, 2 = unsatisfied, 3 = fair, 4 = satisfied and 5 = very satisfied). At 8 wks
      patients will be assessed for post-natal depression using Edinburgh postnatal depression
      scale.

      Patients will be contacted by telephone by one of the blinded investigator at 3, 6 months
      after the surgery. The short form brief pain inventory will be used to determine post-CS
      chronic pain
    

Intervention name(s): Morphine; Placebo
Intervention type(s): Drug; Drug
Intervention description(s): Morphine group will receive intrathecal 11 mg of hyperbaric bupivacaine (2.2 mL 0.5%), 10 μg of fentanyl (0.2 ml) and 100 μg of preservative free morphine (0.1 ml).; Placebo group will receive 11 mg of hyperbaric bupivacaine (2.2 mL 0.5%), 10 μg of fentanyl (0.2 ml) and normal saline (0.1ml)
Intervention MeSH terms: Morphine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Prevention