Topicalisation of the Airway
Extubation can be a time of intense physiological stimulation for patients, with potential adverse consequences.
Different methods to obtund this response have been tried, and this paper examines the effectiveness of applying local anaesthetic to the larynx at the time of initial laryngoscopy.
The original blog post can be viewed here.
Laryngotracheal Topicalization with Lidocaine Before Intubation Decreases the Incidence of Coughing on Emergence from General Anaesthesia. Anesthesia & Analgesia. Oct 2004
Different methods to obtund this response have been tried, and this paper examines the effectiveness of applying local anaesthetic to the larynx at the time of initial laryngoscopy.
The original blog post can be viewed here.
Laryngotracheal Topicalization with Lidocaine Before Intubation Decreases the Incidence of Coughing on Emergence from General Anaesthesia. Anesthesia & Analgesia. Oct 2004
What's it About?
Incidence of coughing at extubation 38 - 96%
Adverse effects associated with this, including raised BP, HR, ICP and intra-ocular pressure.
Authors cite that topicalisation of the airway with local anaesthetic has not been well investigated as an answer to this.
Design: Double-blinded, randomised, placebo-controlled study.
Comparison: 4ml 4% lidocaine (160mg) vs 4ml 0.9% NaCl
Inclusion: ASA 1/2. Elective gynae surgery of 30-120 mins. Need for intubation.
Exclusion: Regurgitation risk factors. Anticipated difficult airway. Smokers. Respiratory tract infection
Other stuff: Lidocaine or NaCl administered via a 'LTA 360 kit', spraying the inner surface of the airway. Anaesthetic technique fairly standardised with some flexibility allowed.
Adverse effects associated with this, including raised BP, HR, ICP and intra-ocular pressure.
Authors cite that topicalisation of the airway with local anaesthetic has not been well investigated as an answer to this.
Design: Double-blinded, randomised, placebo-controlled study.
Comparison: 4ml 4% lidocaine (160mg) vs 4ml 0.9% NaCl
Inclusion: ASA 1/2. Elective gynae surgery of 30-120 mins. Need for intubation.
Exclusion: Regurgitation risk factors. Anticipated difficult airway. Smokers. Respiratory tract infection
Other stuff: Lidocaine or NaCl administered via a 'LTA 360 kit', spraying the inner surface of the airway. Anaesthetic technique fairly standardised with some flexibility allowed.
What Did They Find?
Numbers: 54 patients recruited. 4 excluded (2 difficult laryngoscopies, 1 removed tube (?!), 1 had excess opioids). Resulted in 27 in placebo group, 23 in lidocaine group.
Results: 26% of lidocaine group coughed before extubation, 70% of the placebo group coughed before extubation (p<0.01). 4.3% of lidocaine group coughed post extubation, 30% of placebo group did (p=0.022).
Confounding: No major differences between groups noted
Results: 26% of lidocaine group coughed before extubation, 70% of the placebo group coughed before extubation (p<0.01). 4.3% of lidocaine group coughed post extubation, 30% of placebo group did (p=0.022).
Confounding: No major differences between groups noted
Is it any Good?
Overall: Very good
Strengths: Good design; randomised, placebo controlled, double blinded. Power calculations done and appropriate. Standardised anaesthetic but some practical flexibility.
Weaknesses: Unclear validity of their assessment of cough severity, but well described. Quite a specific sample population.
Strengths: Good design; randomised, placebo controlled, double blinded. Power calculations done and appropriate. Standardised anaesthetic but some practical flexibility.
Weaknesses: Unclear validity of their assessment of cough severity, but well described. Quite a specific sample population.
Final Thoughts
Well designed and implemented study.
Strong suggestion of reduced coughing with topicalisation of airway with 4% lidocaine.
Unclear how alternative techniques of topicalisation may compare (e.g. alternative strengths of local, different methods of application).
Doesn't assess other adverse features associated with extubation e.g. hypertension.
Not set up to look at risks associated with this technique, though none described.
Strong suggestion of reduced coughing with topicalisation of airway with 4% lidocaine.
Unclear how alternative techniques of topicalisation may compare (e.g. alternative strengths of local, different methods of application).
Doesn't assess other adverse features associated with extubation e.g. hypertension.
Not set up to look at risks associated with this technique, though none described.
Written: Tom Heaton
Reviewed; Not done
Reviewed; Not done