Post-anesthetic shivering (PAS) is distressing to the patient, as is pain and postoperative nausea and vomiting (PONV). Shivering during neuraxial anesthesia is a common and distressing side effect. Spinal and epidural anesthesia causes vasodilatation due to sympathetic blockage. Nonpharmacological measures of managing shivering involve using additional drape covers and blankets. Numerous drugs have been used in the interventional management of shivering. Dexmedetomidine is a selective alpha 2 adrenergic agonist with 1600 times greater selectivity for the alpha 2 adrenoceptor than the alpha 1 receptor. It produces sedation, anxiolysis, hypnosis, analgesia, and sympatholytic, and has antishivering properties. Dexamethasone is a potent corticosteroid medication used in the treatment of a variety of conditions. It has been found to reduce the gradient between skin and body core temperature which could help reduce shivering by regulating body’s immune responses. Trials have been conducted that have proven the efficacy of Dexmedetomidine in controlling PAS. However, limited studies have been conducted on the efficacy of newer agents like 5-HT3 receptor antagonists and corticosteroids (Dexamethasone) on PAS. Hence, our aim in this study is to compare the efficacy of Dexmedetomidine and dexamethasone in preventing post-spinal shivering.

Study Design

Prospective Randomised double-blinded Study.

Study Period

Data will be collected within 18 months of span after getting ethical clerance

CTRI Registration – This will be done after getting the IEC certificate.

Sample size

We calculated the sample for a power of 80 percent , alpha  error of 5 percent , and 95 percent  confidence interval. We also added 5 percent  for loss to follow-up, which gave a sample size of 41 per group, a total of 82 patients.

Randomisation – Simple randomization by computer-generated non repeating random number tables.

Inclusion criteria

1. Patients aged between 18 to 60 years of either gender.

2. Patients of ASA physical status I and II.

3. Patients willing to participate.

4. Operative procedures requiring Spinal Anaesthesia.

Exclusion criteria

1. Patients’ refusal to participate.

2. Patients with a known allergy to any of the study drugs, cardiac conduction defects, renal or hepatic impairment.

3. Any contraindications to spinal anesthesia.

4. Any contraindication to steroid therapy.

5. Parturients.

In this prospective randomized, single-blind study, 82 ASA I or ASA II adult patients scheduled for elective infraumbilical surgery under spinal anesthesia who will be willing to participate and fulfill the inclusion criteria will be enrolled and randomly allocated to either Group-S (n=41) to receive Inj. Dexamethasone 8 mg Or Group-D (n=41) to receive Inj. Dexmedetomidine 1 mcg kg -1 body weight iv after induction with spinal anesthesia. After obtaining written informed consent, the patients will be randomized by computer generated random table numbers inserted into an envelope assigned into two groups –

Group S – Dexamethasone group (8 mg dexamethasone)

Group D – Dexmedetomidine group (1 mcg kg -1)

Methodology

Patients willing to participate in our study of age group 18 – 60 years belonging to ASA physical status I or II posted for elective infraumbilical surgery under spinal anesthesia will be randomly allocated to any one of the two groups –

 Inj. Dexamethasone (group S)

 Inj. Dexmedetomidine (group D)

1. Inj. Dexamethasone is available in a 2 ml (8 mg) vial. A 20 ml syringe will be loaded with 2 ml of the drug and diluted with normal saline to a total solution of 20 ml. The injection will be given slowly over 20 minutes. After freeing the syringe of air, it will be connected to the IV extension line, and the other end will be connected to a three-way cannula.

2. Inj. Dexmedetomidine will be prepared in a 20ml syringe with normal saline at a concentration of 5mcg per ml. After freeing the syringe of air, it will be connected to the IV extension line. The other end will be connected to a three-way cannula, and it will be given slowly over 20 min at a dose of 1 mcg per kg body weight.

The patient’s general status, NPO status, consent, weight, and height will be obtained. BMI will be calculated accordingly. An intravenous (IV) access will be secured, preferably with a wide bore cannula in the pre-operative ward. Standard monitoring like non-invasive blood pressure (NIBP), SpO2, HR, ECG and temperature will be attached and base line parameters will be recorded in the operation theatre. A single layer of surgical drapes will cover all the patients, exposing only the surgical site. IV fluids will be used at the operating room temperature.

Before administering spinal anesthesia, 10 ml kg-1 hour-1 of Lactated Ringer’s fluid will be administered. Oxygen will be supplemented as per requirement by using a face mask at a rate 5 L per min. All the patients will be placed in the sitting position, and under strict aseptic precautions, the subarachnoid block will be given in L3-L4 or L4-L5 interspace after infiltrating skin with 2 ml of 2 percent lignocaine. 25G Quincke needle will be inserted intrathecally and 15mg of 0.5 percent hyperbaric bupivacaine (3ml) will be injected after checking for free flow of clear CSF. The patient will be made to lie down in a supine position. The time of the subarachnoid block will be noted. Surgery will be commenced after the level of sensory block reaches T8. The prepared study drug will be attached to the syringe pump and set according to the patient’s body weight. The study drugs will be infused over 20 mins. Patients will be monitored for 60 minutes after administering the drug or till the end of the surgery, whichever will be longer, and the incidence of shivering will be noted till surgery is over; 1st episode of shivering from the administration of spinal anesthesia will also be noted. Shivering will be evaluated every 10 minutes during the operation and after recovery till discharge from PACU. Shivering will be graded according to the following categories:

0 = no shivering,

1 = piloerection or peripheral vasoconstriction but no visible shivering.

 2 = muscular activity in only one muscle group.

 3 = muscular activity in more than one muscle group but not generalized shivering.

4 = shivering involving the whole body.

A score  of 1-2 will be considered as moderate shivering and

3-4 as severe shivering. 

Blinding

The drugs will be prepared by an independent clinician not involved in the study. The anesthesiologist performing the block and observing the patient will be blinded to the treatment group. Neither the patient nor the attending anesthesiologist collecting the data will know the group allocation.

The level of sedation will be assessed using the Ramsay Sedation Score.

Tramadol will be administered intravenously 0.5 mg.kg-1 to patients with shivering of grade 3 or higher.

Hypotension is defined as mean blood pressure of less than 65 mmHg or a fall of more than 20% from the baseline. Hypotension will be treated with Inj. Mephentermine 6mg IV. Bradycardia is defined as HR of less than 50 beats per minute. Bradycardia will be treated with Inj. Atropine 0.6 mg IV. Any other adverse effect during the study period will be noted.