Background

Awake fibreoptic intubation (AFOI) is the gold standard for securing the airway in patients with anticipated difficult airways because it preserves spontaneous ventilation and airway reflexes. However, successful AFOI depends on achieving an optimal balance between adequate sedation, analgesia, patient cooperation, and hemodynamic stability without causing respiratory depression. Dexmedetomidine is widely used because it provides cooperative sedation but is associated with bradycardia and hypotension. A combination of subanaesthetic intravenous ketamine and lignocaine may provide effective sedation, analgesia, and airway reflex suppression while maintaining cardiovascular stability. This study compared the efficacy and safety of intravenous ketamine–lignocaine with dexmedetomidine for AFOI.

Objectives

Primary objective:

• To compare the effectiveness of subanaesthetic intravenous ketamine plus lignocaine versus intravenous dexmedetomidine in achieving optimal intubating conditions during awake fibreoptic intubation.

Secondary objectives:

• To compare hemodynamic parameters.
• To evaluate opioid (fentanyl) requirement.
• To compare adverse events associated with both regimens.

Methodology

This was a prospective, randomized, triple-blinded clinical trial conducted over 18 months at AIIMS Raipur. One hundred ASA I–II patients aged 18–60 years with anticipated difficult airway (El-Ganzouri score 4–12) undergoing elective surgery were randomized into two equal groups (n=50 each).

• Group KL: Ketamine 0.3 mg/kg IV bolus + infusion 0.3 mg/kg/h with lignocaine 1.5 mg/kg IV bolus + infusion 1.5 mg/kg/h.
• Group D: Dexmedetomidine 1 µg/kg over 10 minutes followed by infusion 0.2–0.7 µg/kg/h.

Primary outcomes included Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) score, endoscopy time, intubation time, endoscopist satisfaction, patient discomfort, and postoperative recall. Secondary outcomes included heart rate, mean arterial pressure, oxygen saturation, opioid requirement, and adverse events.

Results

Baseline characteristics including age, gender, BMI, ASA status, and El-Ganzouri score were comparable between groups (all p > 0.05).

Compared with dexmedetomidine, the ketamine–lignocaine group demonstrated:

• Deeper sedation: MOAA/S score 2.82 ± 0.72 vs 3.12 ± 0.72 (p = 0.040).
• Significantly shorter intubation time: 21.22 ± 9.06 s vs 34.96 ± 10.80 s (p < 0.001).
• Lower patient discomfort: 1.84 ± 0.79 vs 2.26 ± 0.96 (p = 0.027).
• Comparable endoscopy time (2.55 ± 1.24 vs 2.96 ± 1.43 min; p = 0.107) and endoscopist satisfaction (p = 0.119).

Postoperative recall was significantly lower in the ketamine–lignocaine group during:

• Topical anaesthesia (12% vs 38%; p = 0.003).
• Intubation (36% vs 78%; p < 0.001).

There was no significant difference in recall of pre-anaesthetic preparation (p = 0.099) or endoscopy (p = 0.202). Adverse events were comparable between groups (16% vs 12%; p = 0.564). Hemodynamically, dexmedetomidine produced lower heart rate and mean arterial pressure, whereas ketamine–lignocaine caused transient increases during intubation that remained clinically acceptable.

Discussion

The study demonstrated that ketamine combined with lignocaine provided superior intubating conditions compared with dexmedetomidine. Patients experienced deeper yet cooperative sedation, faster intubation, less discomfort, lower recall during airway manipulation, and reduced opioid requirement while maintaining adequate oxygenation and acceptable hemodynamic stability. Although dexmedetomidine offered stable sedation, its tendency to produce bradycardia and hypotension may limit its use in selected patients. The findings support the complementary pharmacological effects of ketamine and lignocaine in improving airway conditions without increasing complications.

Conclusion

Subanaesthetic intravenous ketamine combined with lignocaine is an effective and safe alternative to dexmedetomidine for awake fibreoptic intubation in anticipated difficult airways. It provides significantly better intubating conditions, shorter intubation time, reduced patient discomfort and recall, and lower opioid requirement while maintaining clinically acceptable hemodynamic stability and a safety profile comparable to dexmedetomidine.