Plasma concentrations of lignocaine during fibreoptic bronchoscopy.

Abstract

Peak plasma concentrations of lignocaine were recorded in 41 patients receiving topically applied lignocaine for fibreoptic bronchoscopy. Adequate anaesthesia was achieved in all patients with an average dose per unit weight of 9 3 + 0 5 mg/kg (SEM) giving a mean peak plasma concentration of 2-9 + 0.5 mg/1-1 (SEM) (± SE 0.5). The plasma concentration exceeded toxic levels of 5.0 mg/l-1 in only two patients, and no complications were observed. Peak concentrations were influenced only by dose per unit weight administered and not by factors considered likely to influence mucosal absorption from the bronchial tree, such as sputum production, airflow obstruction, or cigarette smoking. A major proportion of the total dose of lignocaine was requited to anaesthetise the nose, pharynx, and larynx, only a small proportion being needed for the bronchial tree. Lignocaine gel (20% w/v) was preferred by patients, and in a study of 10 volunteers, produced lower plasma concentrations when used as a topical anaesthetic than did lignocaine aerosol (100% w/v) or lignocaine solution (4 % w/v).Fibreoptic bronchoscopy is safe and simple, but topical anaesthesia of the upper respiratory tract is necessary for adequate examination. Lignocaine is commonly used but is well absorbed from mucosal surfaces, producing significant plasma concentrations' and may therefore not be ideal.2 Lignocaine toxicity is related to plasma concentrations3 and levels in excess of 5 mg/l-1 may result in convulsions4 or heart block.5 6 Little is known of the comparative mucosal absorption of the common preparations of lignocaine: 2% w/v gel; 4% w/v solution (also 1 % w/v), and 10% w/v aerosol. Lignocaine solution when applied to the respiratory tract is absorbed from mucosa of the tracheobronchial tree or even alveoli.

Which is Safer to Avoid an Increase in ICP After Endotracheal Suctioning in Severe Head Injury: Intravenous or Endotracheal Lidocaine?

“…For ETL dosage in our study we used 1 mg/kg of lidocaine while Groeben et al [25] used 5 mg/kg and had a lidocaine plasma concentration of 1.5 ± 0.14 μg/mL, that suggests that the level of lidocaine in our patients' plasma was lower than 1.5 μg/mL. There are conflicting views in studies regarding maximum safe doses of local anesthetic drugs [30][31][32][33]. There was direct correlation between pharmacological effect of lidocaine [30,31] and blood concentration of lidocaine in arterial plasma at which symptoms of local anesthetic toxicity were evident ranging from 2.0 to 6.0 μg/mL [34].…”

Monitoring, Sedation, and Anesthesia for Flexible Fiberoptic Bronchoscopy

“…The maximum lidocaine level was found to be 3.79 μg/ml in a patient with hepatic metastases who only received 420 mg topical lidocaine (LeLorier et al, 1979). A follow-up study in 1982 by Efthimiou et al of 41 FOB patients used a similar mean lidocaine dose (9.3 ± 0.5 mg/kg); mean peak levels were 2.9 ± 0.5 μg/ml and two patients had a lidocaine level > 5 μg/ml with no complications (Efthimiou et al, 1982). Ameer et al compared an elderly group of 14 patients (mean age of 67 years) with a young group of five patients (mean age of 42 years).…”

“…These studies evaluating lidocaine dosing have been done to evaluate a variety of techniques in application of topical anesthesia (Ameer et al, 1989;Amitai et al, 1990, Berger et al, 1989Boye & Bresden, 1979;Efthimiou et al, 1982;Gjonaj et al, 1997;Gomez et al, 1983;Jones et al, 1982;Karvonen et al, 1976;Korttila et al, 1981;Langmack et al, 2000;Le Lorier et al, 1979;Loukides et al, 2000;Mainland et al, 2001;McBurney et al, 1984;Milman et al, 1998;Patterson et al, 1975;Smith et al, 1985;Sucena et al, 2004;Sutherland et al, 1985). These twenty studies were reviewed by Frey et al in their study of lidocaine dosing (Frey et al, 2008).…”

Takotsubo Cardiomyopathy and Subsequent Seizures Induced by Flexible Bronchoscopy

“…14 Earlier studies showed that most patients have a peak plasma concentration well below the toxic level even with high doses of topical lidocaine, 15,16 so the relationship between seizure and topical lidocaine is considered to be obscure. Because the total dose of topical anesthesia was 500 mg (9.7 mg/kg), it is probable that the high dose induced her cardiac event or seizures.…”