Impact of Dexamethasone on the Duration of Sensory and Motor Block Following Spinal Anesthesia
Condition: Spinal Anesthesia; Prolonged Sensory Block; Prolonged Motor Block
Study type: Interventional

Summary: 
      The purpose of this study is to assess the effect of a single-dose of intravenous
      dexamethasone 8 mg on the duration of sensory and motor blockade following spinal anesthesia
      with isobaric bupivacaine.

      The hypothesis of the study is that intravenous dexamethasone will significantly prolong (by
      more than 20 minutes) the duration of spinal anesthesia.
    

Detailed description: 
      Spinal anesthesia is commonly used for lower body surgery. The injection of local anesthetics
      in the lumbar intrathecal space allows the desensitization of the lower body by blocking
      sensory and motor nerve roots. In return, spinal anesthesia causes a sympathetic block which
      is associated with deleterious hemodynamic effects such as hypotension.

      Using intravenous or intrathecal adjuvants to local anesthetics may prolong the duration of
      sensory and motor blockade following spinal anesthesia. Various intrathecal additives have
      been studied such as opioids, adrenalin, clonidine, dexmedetomidine, midazolam, ketamine,
      magnesium, ketorolac and neostigmine. Most of them failed to prolong the duration of spinal
      anesthesia and side-effects have restricted their use.

      Dexamethasone is a potent corticosteroid with a half-life of 36 to 72 hours and an onset of
      action of 1 to 2 hours. The safety of single doses of intravenous dexamethasone is well
      documented. Dexamethasone is widely used in anesthesia to prevent nausea and vomiting and
      treat post-extubation sore throat and postoperative shivering. It is also increasingly used
      in orthopaedic surgery to reduce opioid needs without increasing the risks of infection,
      wound dehiscence and osteonecrosis. The use of dexamethasone in the perioperative period
      reduces postoperative edema allowing early mobilization and improved functional recovery.

      Recent studies have demonstrated that both perineural and intrathecal administration of
      dexamethasone can prolong the duration of peripheral and spinal anesthesia. However,
      dexamethasone has not been approved by health authorities for these indications and thus, the
      safety of this practice remains controversial. A recent study has compared peripheral to
      intravenous administration of dexamethasone for interscalene blocks. This study demonstrated
      the equivalency of these regimens in increasing the analgesic duration of a single-shot
      interscalene block.

      The impact of intravenous dexamethasone on the duration of spinal anesthesia remains unknown.
      This study will investigate the effect of a single-dose of dexamethasone 8 mg on the duration
      of the sensory and motor block following spinal anesthesia.

      Sixty patients scheduled for lower body surgery under spinal anesthesia will be considered
      for this study.

      After placement of standard non-invasive monitoring, spinal anesthesia will be performed in
      the sitting position using a 25 gauge (GA) pencil point needle (Whitacre, Pencan). After
      aspiration of cerebrospinal fluid (CSF), a dose of isobaric 0.5% bupivacaine 12 mg will be
      injected. The aspiration of CSF will be repeated at the end of the injection. While
      performing spinal anesthesia, an intravenous infusion of dexamethasone 8 mg or placebo will
      be initiated according to randomization.

      Subsequently, the patient will be placed in supine position. Sensory block will be measured
      by loss of sensation to pinprick at 5, 10, 20 and 30 minutes following spinal anesthesia and
      then every 15 minutes until confirmation of regression by two dermatomes. Loss of sensation
      will be assessed every 30 minutes thereafter. Motor block will be assessed using the Bromage
      scale at the same frequency until full recovery.

      Sedation will be allowed during the performance of the spinal anesthesia technique and
      surgery. In case of unsatisfactory quality of spinal anesthesia, general anesthesia will be
      performed.

      At the end of surgery, patients will be transferred to the recovery room. Multimodal
      analgesia including celecoxib and acetaminophen will be administered. Pain will be assessed
      using a verbal numeric pain scale (VNPS) of 0 to 10, where 0 means "No pain" and 10 means
      "Worst pain imaginable". Intravenous hydromorphone will be administered when VNPS is superior
      to 3. Postoperative nausea and vomiting will be managed with intravenous ondansetron,
      dimenhydrinate and haloperidol.

      Opioid intake, presence of side-effects and quality of sleep will be assessed during the
      first 24 hours following surgery.
    

Intervention name(s): Dexamethasone; Normal saline
Intervention type(s): Drug; Drug
Intervention description(s): Administration of a single-dose of intravenous dexamethasone 8 mg during spinal anesthesia; Administration of a single-dose of Normal saline during spinal anesthesia
Other intervention name(s): Decadron; Placebo
Intervention MeSH terms: Dexamethasone
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Prospective, randomized, double-blind, placebo-controlled study
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Other
Keywords: Spinal anesthesia; Motor block; Sensory block; Dexamethasone