Propofol is widely used for induction of anesthesia because of its rapid onset and smooth recovery. However, pain during intravenous injection remains a major drawback, reported in up to 90% of patients. This pain negatively affects patient comfort and satisfaction.

Several strategies have been attempted to reduce propofol injection pain, including use of large veins, cooling or warming propofol, slow injection, and pretreatment with drugs such as lignocaine, opioids, and non-steroidal anti-inflammatory drugs. Among these, lignocaine is most commonly used, but it does not completely abolish the pain in all patients.

Ketamine is a dissociative anesthetic with potent analgesic properties mediated through NMDA receptor antagonism. In sub-anesthetic doses, ketamine provides effective analgesia without producing significant psychomimetic effects. Low-dose ketamine has been used successfully to attenuate pain associated with intravenous injections.

The present study was undertaken to evaluate the efficacy of low-dose ketamine in reducing propofol injection pain and to determine the most effective dose with minimal side effects.

Study Design:- Prospective, randomized, double-blind controlled study.

Study Setting:- Department of Anaesthesiology, tertiary care teaching hospital in India.

Ethical Approval

The study was conducted after approval from the Institutional Ethics Committee and obtaining written informed consent from all patients.

Sample Size:- 90 patients.

Inclusion Criteria

• Age 18–60 years
• ASA physical status I & II
• Elective surgeries under general anesthesia

Exclusion Criteria

• Allergy to ketamine or propofol
• Psychiatric illness
• Pregnancy and lactation
• Cardiovascular or neurological disorders

Grouping

Methodology

• 18G IV cannula placed on dorsum of hand
• Study drug administered IV 1 minute before propofol
• Propofol injected at standard rate
• Pain assessed before loss of consciousness

Pain Assessment Scale

Verbal Pain Score (VPS):

Table 1: Demographic Data

Demographic parameters were comparable (p > 0.05).

Table 2: Incidence of Pain on Propofol Injection

Table 3: Comparison of Mean Pain Scores

p < 0.001 (statistically significant)

Table 4: Hemodynamic Parameters

No clinically significant hemodynamic changes observed.

Table 5: Adverse Effects

The results of this study clearly indicate that low-dose ketamine significantly reduces pain associated with propofol injection. Ketamine 0.3 mg/kg was superior to 0.2 mg/kg in reducing both incidence and severity of pain.

Ketamine acts by inhibiting NMDA receptors and providing peripheral analgesia. Its use in low doses avoids psychomimetic effects, making it suitable for routine anesthesia practice.

These findings correlate well with previously published Indian and international studies, which report effective attenuation of propofol injection pain with sub-anesthetic ketamine doses.

Low-dose ketamine is an effective and safe method for reducing propofol injection pain. A dose of 0.3 mg/kg IV provides optimal pain relief without significant side effects and can be routinely used during anesthesia induction.

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