MedWire News: Atomized lidocaine 2% is effective for awake oral fiberoptic intubation in morbidly obese patients and provides superior intubating conditions to lidocaine 1%, say Canadian researchers.

“This technique has particular merit because it is effective, rapid, safe, and requires minimal patient sedation to achieve excellent intubating conditions,” say Steven Backman, from the MUHC-Royal Victoria Hospital in Montreal, Quebec, and colleagues.

Having previously demonstrated the efficacy of atomized lidocaine 2% and 4% to achieve topical airway anesthesia in morbidly obese patients, the researchers sought to determine the lowest optimum dose that could be used.

They randomly assigned 21 morbidly obese patients to receive 40 mL of atomized 1% or 2% lidocaine with high oxygen flow as carrier for awake oral fiberoptic intubation.

Airway topicalization was achieved within an average of 4.7 minutes. The total time of airway manipulation – from the start of airway topicalization to cuff inflation – was longer in patients receiving 1% lidocaine than in those received 2% lidocaine, at 8.6 versus 6.9 minutes.

The researchers note that patients receiving 2% lidocaine had lower response scores to airway manipulation, with 80% of the responses graded as no response compared with only 39% of those treated with 1% lidocaine. The median bronchoscopists’ satisfaction scores were also lower in the 2% than in the 1% lidocaine group, at 5 versus 4.

The patients’ tolerance scores to topicalization were similar in the two groups and there was no significant difference in hemodynamic responses to topicalization and airway manipulation.

Peak plasma concentration was lower in patients receiving 1% lidocaine than in patients receiving 2% lidocaine, at 1.4 versus 3.8 µg/mL.

In both the 1% and 2% groups, the total dose of local anesthetic administered exceeded that normally recommended for  lidocaine (5 mg/kg), but the researchers note that there were no signs of clinical toxicity.

Their research, published in the journal Anaesthesia, concludes that “there is a clear difference in the 1% and 2% groups with regard to their responses to airway manipulation.”

The team adds: “This is not only derived from our results, but by the extensive experience we have with using atomized lidocaine 2% for airway topicalization.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009.