Prevention of Shivering After Spinal Anesthesia
Condition: Postoperative Shivering
Study type: Interventional
Phase: Phase 4

Summary: 
      Recently, ketamine and dexmedetomidine have been used to prevent shivering during
      anaesthesia, with good results. Ketamine (a competitive NMDA receptor antagonist) plays a
      role in thermoregulation at various levels and ketamine, has been shown to inhibit
      postoperative shivering in some reports and studies.
    

Detailed description: 
      Spinal anaesthesia is a safe and popular anaesthetic technique for various surgeries. Around
      40-60% of the patients under spinal anaesthesia develop shivering.The main causes of
      shivering intra and postoperatively are temperature loss, decreased sympathetic tone and
      systemic release of pyrogens. Hypothermia during neuraxial anesthesia develops initially from
      core to peripheral redistribution of body heat. Redistribution of body heat during spinal or
      epidural anesthesia typically decreases core body temperature 0.5-1.0 degree Celsius.

      Shivering is characterised by involuntary oscillatory contractions of skeletal muscles. Once
      the body is exposed to cold, it is a physiological response for heat preservation after
      peripheral vasoconstriction. Postoperative shivering is defined as the fasciculation of the
      face, jaw or head or muscle hyperactivity, lasting longer than 15 seconds. It is a common and
      challenging aspect of anaesthesia and targeted temperature modulation because it leads to
      increase oxygen consumption and increases the risk of hypoxia.

      The most frequent complication in postoperative period is shivering which is reported to be
      between 20-70% after general anaesthesia. The incidence reported in previous studies are
      5-65% after general anaesthesia and 30-33% after epidural procedures. The overall shivering
      incidence in a recent meta-analysis was 34%.

      The underlying pathology of shivering is not fully understood yet, therefore the definitive
      treatment and prevention has not been established till date. Due to its importance as
      postoperative complication and the lack of available data about aetiology and treatment, this
      narrative review of the published literature on this topic is essential.

      Various pharmacological agents being used for prophylaxis and treatment of post spinal
      shivering are Opioids like fentanyl, tramadol, pethidine, Anticholinergics like
      physostigmine, NMDA receptor antagonist like ketamine and the latest being alpha-2
      antagonists like clonidine, dexmedetomidine.

      Recently, ketamine and dexmedetomidine have been used to prevent shivering during
      anaesthesia, with good results. Ketamine (a competitive NMDA receptor antagonist) plays a
      role in thermoregulation at various levels and ketamine, has been shown to inhibit
      postoperative shivering in some reports and studies.

      Dexmedetomidine, a centrally acting alpha 2-adrenergic agonist, has been used as a sedative
      agent and is known to reduce the shivering threshold. Dexmedetomidine also provided sedation
      which is sufficient to prevent the anxiety without any adverse effects. And until date, there
      are limited studies using dexmedetomidine in the treatment of postoperative shivering.

      A very limited data is available on this subject in our Pakistani population. Pethidine is
      drug of choice for the prevention and treatment of shivering. Due to the non-availability of
      Pethidine, doctors are looking for newer and better options. Considering this, a study is
      designed to compare between Dexmedetomidine and Ketamine, as they are easily available and
      very few studies are done till date comparing them, as ketamine isn't researched much as an
      anti-shivering agent as it is known for undesirable side effects like delirium and
      hallucinations and dexmedetomidine being a newer agent. Results of this study will help to
      select the better prophylactic option for prevention of shivering after spinal anaesthesia in
      our general population.
    

Intervention name(s): Dexmedetomidine; Ketamine
Intervention type(s): Drug; Drug
Intervention description(s): 0.5 micrograms/kg diluted in 10mL of normal saline 0.9% given as IV infusion over 10 minutes; 0.5 milligrams/kg diluted in 10mL of normal saline 0.9% given as IV infusion over 10 minutes
Intervention MeSH terms: Dexmedetomidine; Ketamine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Spinal anesthesia; Postoperative Shivering; Dexmedetomidine