This randomized, double-blind, controlled clinical trial investigates the efficacy of a sub-anesthetic dose of ketamine (0.5 mg/kg IV) in preventing post-spinal hypotension in patients undergoing elective orthopedic surgeries under spinal anesthesia. The study compares ketamine with placebo (normal saline) in terms of blood pressure stability and incidence of hypotensive episodes following spinal anesthesia.
Spinal anesthesia is commonly used for orthopedic procedures due to its effectiveness and favorable recovery profile. However, spinal-induced hypotension is a frequent complication resulting from sympathetic blockade, which can compromise organ perfusion and increase perioperative risk. This study aims to determine whether a single sub-anesthetic dose of intravenous ketamine administered before spinal anesthesia can reduce the incidence of hypotension. Patients will be randomly allocated to either a ketamine group (receiving 0.5 mg/kg ketamine IV diluted in Ringer's lactate) or a control group (receiving volume-equivalent normal saline). Both interventions are administered over 20 minutes prior to the spinal injection to ensure blinding. All patients will undergo standard spinal anesthesia with 0.5% heavy bupivacaine plus fentanyl. Primary outcome is the incidence of hypotension (defined as a mean arterial pressure drop \>20% from baseline). Secondary outcomes include bradycardia, nausea, vomiting, hallucinations, and total dose of vasopressors required. The findings aim to support or refute the use of ketamine as a prophylactic strategy to stabilize hemodynamics during spinal anesthesia.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
30
Patients receive crystalloid preloading of 15ml/kg (Ringer's lactate) +the sub-anesthetic dose of ketamine of 0.5 mg/kg IV added to the first bottle of ringer for blinding over 20 min before the spinal injection.
Patients receive a crystalloid preloading of 15 ml/kg (Ringer's lactate)+ 0.5 mg/kg IV of Normal Saline added to the first bottle of ringer for blinding, over 20 min before the spinal injection.
Ain Shams University Hospitals
Cairo, Egypt
RECRUITINGIncidence of Post-Spinal Hypotension
Hypotension is defined as a mean arterial pressure (MAP) less than 20% below baseline. MAP will be calculated using the formula: MAP = DBP + (SBP - DBP)/3. Hypotension will be treated with boluses of IV Ephedrine (3mg) and repeated if needed. The total dose of ephedrine required to correct hypotension and raise the MAP to the baseline will be recorded.
Time frame: From spinal injection to end of surgery
Incidence of Hallucinations
Visual or auditory disturbances post ketamine administration. Midazolam (2 mg IV) will be given pre-injection to mitigate risk.
Time frame: From spinal injection to end of surgery
Incidence of Bradycardia
Bradycardia is defined as Heart Rate less than 50 beats per minute. Bradycardia will be treated with IV atropine (0.04 mg/kg) and repeated if needed.
Time frame: From spinal injection to end of surgery
Incidence of Nausea and Vomiting
Nausea is defined as an unpleasant subjective urge to vomit and Vomiting is defined as propulsive abdominal muscular spasms associated with the expulsion of gastric contents. Nausea and vomiting will be treated with 3 mg IV Granisetron.
Time frame: From spinal injection to end of surgery
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