British journal of anaesthesia
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Review Meta Analysis
Intravenous lidocaine to prevent postoperative airway complications in adults: a systematic review and meta-analysis.
Cough: why care?
Although often minor, common post-operative complications have by definition a broad impact on the perioperative experience. Some common complications, such as coughing on extubation, can also have significant surgical consequences such as for neurosurgical or ophthalmic procedures.
Both coughing on extubation (reported incidence 15-94%) and post-operative sore throat (21-72%) are very common among surgical patients.
What did they do?
Yang and team performed a high-quality meta-analysis of RCTs investigating the effect of intravenous lidocaine/lignocaine on coughing at extubation. Many of these trials also looked at further secondary effects, such as post-operative sore throat. They included 16 trials, totalling 1,516 subjects. Although the trials demonstrated significant heterogeneity, subgroup analyses still confirmed the study's findings.
And they found...
There was significant reduction in cough RR 0.64 (0.48-0.86 & NNT=5), and post-operative sore throat RR 0.46 (0.32-0.67), though no difference in laryngospasm, adverse events or time to extubation with modern volatile agents.
Analysing various lidocaine timings (pre-operative vs intra-operative) and dose ranges (low <1.5mg/kg or high >1.5 mg/kg) yielded no evidence of clear advantage. Nonetheless the findings are consistent with previous reviews, such as from Clivio et al. (2019) showing lidocaine 1.5 mg/kg reduced cough (RR: 0.44; 0.33–0.58), and that the effect is probably dose responsive.
Ok, but how does lidocaine work?
The mechanism of action reducing cough is not understood, although several possibilities have been proposed, including...
"...the suppression of airway sensory C fibres, the reduction of neural discharge of peripheral nerve fibres, and the selective depression of pain transmission in the spinal cord."
Bottom-line
Peri-operative intravenous lignocaine effectively reduces coughing on extubation and reduces post-operative sore throat, without any increase in adverse events.
summary -
Incomplete peripheral nerve blocks distal to the popliteal region are commonly considered a sciatic and femoral/saphenous nerve block failure. The existence of a much more distal innervation area of the posterior femoral cutaneous nerve (PFCN) as described has not been assumed yet. We therefore investigated the distal termination of the PFCN in the lower leg. ⋯ The PFCN has a much more distal termination in the lower leg than previously demonstrated. To ensure complete anaesthesia of the lower leg and foot, the PFCN must be included in combined peripheral nerve block procedures.
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Editorial Biography Historical Article
Katharine Georgina Lloyd-Williams, CBE (1896-1973): an inspirational anaesthesia role model.