Peribulbar anesthesia for cataract surgery: effect of lidocaine warming and alkalinization on injection pain, motor and sensory nerve blockade.
OBJECTIVE
To compare self-reported pain and efficacy of warmed, alkalinized, and warmed alkalinized lidocaine with plain 2% lidocaine at room temperature for peribulbar anesthesia in cataract surgery.


METHODS
Through a prospective, single-blinded, randomized, controlled clinical trial 200 patients were divided into four groups. They received either lidocaine at operating room temperature 18 degrees C, control group (Group C), lidocaine warmed to 37 degrees C (Group W), lidocaine alkalinized to a pH of 7.09+/-0.10 (Group B) or lidocaine at 37 degrees C alkalinized to a pH of 6.94+/-0.05 (Group WB). All solutions contained Inj. Hyaluronidase 50 IU/ml. Pain was assessed using a 10-cm visual analog score scale. Time of onset of sensory and motor blockade and time to onset of postoperative pain were recorded by a blinded observer.


RESULTS
Mean pain score was significantly lower in Group B and WB compared with Group C (P<0.001). Onset of analgesia was delayed in Group C compared with Group B (P=0.021) and WB (P<0.001). Mean time taken for the onset of complete akinesia and supplementation required for the block was significantly lower in Group B. Time of onset of pain after operation was significantly earlier in Group W compared with Group C (P=0.036).


CONCLUSIONS
Alkalinized lidocaine with or without warming produced less pain than lidocaine injected at room temperature. Alkalinization enhances the effect of warming for sensory nerve blockade, but warming does not enhance alkalinization, in fact it reduces the efficacy of alkalinized solution for blocking the motor nerves in the eye.
Jaichandran
Venkatakrishnan
V
Department of Anaesthesiology, Vision Research Foundation, Sankara Nethralaya, 41/18, College Road, Nungambakkam, Chennai-600 006, Tamil Nadu, India.
Vijaya
Lingam
L
George
Ronnie Jacob
RJ
InderMohan
Bhanulakshmi
B
D000758:Anesthesia; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002387:Cataract Extraction; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007267:Injections / Q000009:adverse effects; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010146:Pain / Q000209:etiology; D010147:Pain Measurement; D010149:Postoperative Pain; D016037:Single-Blind Method; D013696:Temperature
D000779:Anesthetics, Local; D008012:Lidocaine