Plasma lignocaine levels during paediatric endoscopy of the upper respiratory tract. Relationship with mucosal moistness

LID Study: Plasma lidocaine levels following airway topicalisation for paediatric microlaryngobronchoscopy (MLB)

BACKGROUND

A dose of 5mg/kg lidocaine is considered appropriate for paediatric airway topicalisation. Existing literature suggests younger children are susceptible to toxic lidocaine plasma levels and achieve this at a faster rate.

AIMS

The primary outcome of this study was to ascertain peak plasma lidocaine levels after topicalisation for airway endoscopy. Secondary endpoints included: time to peak lidocaine plasma levels, signs of lidocaine toxicity (restricted to ECG changes or seizures when under anaesthesia) and clinical adverse events of laryngospasm, coughing or desaturation during the procedure.

METHODS

Data was collected prospectively over 18 months at Royal Manchester Children's Hospital. Children aged 0-8 years undergoing elective diagnostic or therapeutic airway endoscopy were included within the study. Standardised 2% lidocaine was used for airway topicalisation. Dose varied depending upon practitioner usual practice. Venous blood sampling occurred at 5, 10, 15 and 20 minutes post administration and plasma lidocaine levels (ng/ml) analysed.

RESULTS

A significant relationship exists between higher peak plasma levels and ages <18 months (p=0.00973). Strong linear correlation exists between body weight and age for our cohort (r=0.88). Higher peak plasma lidocaine levels occur with total dose volumes between 2 and 3mls of 2% lidocaine local anaesthetic (p=0.03) compared with <2ml total dose volumes. Data suggests a potential relationship of lower body weights achieving higher peak plasma levels (p=0.0516). Reduced IQR variation of peak plasma lidocaine levels exists when lidocaine dosing is <5mg/kg.

CONCLUSIONS

Age and total dose volume of topicalised lidocaine have a significant relationship with plasma lidocaine levels. A dose of 5mg/kg topicalised lidocaine for paediatric airway endoscopy is safe and provides good operating conditions. Lower patient body weights trend toward higher peak lidocaine plasma concentrations and require further investigation.

Lignocaine topicalization of the pediatric airway

The application of topical laryngeal lignocaine is a technique used frequently in pediatric anesthesia. It is often used to facilitate open airway procedures, tracheal intubation, or to reduce the incidence of perioperative adverse respiratory events such as coughing and laryngospasm. A number of studies have shown that applying topical lignocaine to the larynx reduces perioperative respiratory adverse events, while others have shown an increased incidence of respiratory complications with lignocaine administration. There is a lack of evidence on the effect of topical lignocaine on the sensitivity of upper airway reflexes and swallowing, the duration of time that airway reflexes are obtunded, and the optimum and safe maximum dose of lignocaine when used by this route. We review the current literature relating to the use of lignocaine to topicalize the pediatric airway. This review concentrates on the indications for use, the maximum safe dose, the effect on swallowing, and risk of aspiration and the complications of the technique.

Awake Tracheal Intubation in an 8-Year-Old Girl with McCune-Albright Syndrome

An 8-year-old girl with McCune-Albright syndrome presented for resection of a very large fibrous dysplasia mass of the face with significant distortion of the airway anatomy. She had significant obstructive sleep apnea with daytime somnolence and hemoglobin oxygen desaturations while breathing room air preoperatively. We were able to successfully manage her airway by providing IV sedation, topical anesthesia of the airway, and oral fiberoptic intubation in close collaboration with our otorhinolaryngology colleagues.

Rigid bronchoscopy for foreign body removal: anaesthesia and ventilation

Foreign body aspiration is a leading cause of death in children 1-3 years old, although mortality is low for children who reach the hospital. Presenting symptoms of an inhaled foreign body depends on time since aspiration. Immediately after inhalation the child starts to cough, wheeze, or have laboured breathing. If the early signs are missed, the child usually presents with fever and other signs and symptoms of chest infection. A plain chest X-ray has relatively low sensitivity and specificity for inhaled foreign body. The gold standard for diagnosis and management of this condition is rigid open tube bronchoscopy under general anaesthesia. For late presentations, time should be taken to fast the child and complete a thorough evaluation before bronchoscopy. The procedure should be performed in a well-equipped room with at least two anaesthesiologists, one with paediatric experience, in attendance. Most experienced anaesthesiologists prefer inhalational rather than intravenous induction of anaesthesia and a ventilating bronchoscope rather than intubation. Equally good results have been reported with spontaneous ventilation or positive pressure ventilation; jet ventilation is not advocated for foreign body removal in children.

Systemic absorption of lidocaine after topical application for the treatment of oral mucositis in bone marrow transplantation patients

This paper evaluates lidocaine absorption via oral mucosa following its topical application for symptomatic treatment of bone marrow transplantation (BMT)-induced oral mucositis. Five patients with high-grade oral mucositis after allogeneic BMT were entered consecutively into the study. Five healthy individuals served as controls. All 10 participants rinsed their mouth with 5 ml of a 2% lidocaine solution for 1 min, after which they expectorated the liquid. Blood samples were drawn at 1, 5, 10, 20, 30 and 60 min after rinsing and centrifuged. Plasma lidocaine levels were measured by fluorescence polarization immunoassay. In the BMT patients, plasma lidocaine levels were lower than the therapeutic range of this drug (0.2 microg/ml vs 1.5-5.5 microg/ml), while in the controls no detectable lidocaine levels were noted. The data from this preliminary study indicate that lidocaine prescribed as an anesthetic mouthwash in BMT patients with oral mucositis results in minor systemic absorption of the drug.

Nebulized lidocaine administered to infants and children undergoing flexible bronchoscopy

STUDY OBJECTIVES

The purpose of this study was to evaluate the safety and efficacy of nebulized lidocaine hydrochloride as a topical anesthetic for use during flexible bronchoscopy in infants and children.

DESIGN

This was a prospective, randomized, double-blind study.

PATIENTS

Twenty consecutive patients scheduled for flexible bronchoscopy who were not intubated and had no known cardiac or hepatic disease comprised the study group.

INTERVENTIONS

The patients were randomized to receive either 8 mg/kg or 4 mg/kg of nebulized 2% lidocaine by face mask prior to bronchoscopy.

SETTING

The study took place in a bronchoscopy suite at an academic medical center.

MEASUREMENTS

To determine systemic absorption, serum lidocaine levels were obtained. To assess efficacy of nebulized lidocaine as a topical anesthetic, changes in heart rate and blood pressure were recorded, and the bronchoscopist (who did not know the lidocaine dose used) rated the ease of passage of the bronchoscope through nose, vocal cords, trachea, bronchi, and all sites overall, and the degree of cough.

RESULTS

Nebulized lidocaine was safe, was well-tolerated, and provided adequate anesthesia for half of the patients. The serum lidocaine levels were much lower than the levels in the toxic range. There was a trend toward easier passage of the bronchoscope in the high-dose group at all sites noted previously that were evaluated.

CONCLUSION

Nebulized lidocaine in doses up to 8 mg/kg appears to be safe and moderately effective as a topical anesthetic for flexible bronchoscopy in infants and children. The serum levels were remarkably low. Fifty percent of the subjects required no supplemental lidocaine.

Lidocaine plasma concentrations in pediatric patients after providing airway topical anesthesia from a calibrated device

The aim of this prospective study was to evaluate plasma lidocaine concentrations in infants and children after laryngeal spray using a calibrated device. Twenty-one patients aged 3 to 24 mo requiring laryngoscopy or bronchoscopy were included in the study. Anesthesia was induced via a mask with halothane up to 2% in 100% O2. Lidocaine was administered using a 5% lidocaine spray. For patients weighing less than 10 kg, one spray (8 mg of lidocaine) was administered. For those weighing from 10 to 20 kg, two sprays (16 mg) were given. The dose of lidocaine administered ranged between 0.9 and 2.6 mg/kg. Maximum plasma lidocaine concentration (Cmax) was 1.05 +/- 0.55 micrograms/mL (mean +/- SD; range 0.24-2.29 micrograms/mL). With this procedure, we demonstrated the safety of administering lidocaine to children by laryngeal spraying using a 5% sprayer.

Comparison of preoperative with postoperative topical lidocaine spray on pain after tonsillectomy

Seventy-five children aged 4-6 years scheduled for tonsillectomy were randomly allocated to receive either topical tonsillar spray with 10% lidocaine 4 mg kg-1 3 minutes before surgical incision; identical tonsillar spray after both tonsils had been removed; or no topical spray (control group). There were significant differences in postoperative pain between the lidocaine groups and the control group at 0.5 and one hour after awaking (P < 0.05). Also in the lidocaine groups, consumption of paracetamol on the day of operation was less, and additional postoperative pethidine was not required. There were no significant differences between pre- and postoperative lidocaine groups in pain scores during the observation period but the use of pre-operative lidocaine tended to be associated with a more rapid return to calm wakefulness. Topical lidocaine seemed to have short-acting analgesic activity. The results of this study do not support the theory of pre-emptive analgesia.

Anaesthesia for airway obstruction in laryngo-onycho-cutaneous syndrome

A 4-year-old boy with laryngo-onycho-cutaneous syndrome underwent excision of an obstructive vocal cord lesion. There is only one previous case report of laryngeal involvement in this syndrome but the anaesthetic management has not been reported. The anaesthetic management for microlaryngobronchoscopy and laser surgery in this child with upper airway obstruction is described.

Serum lidocaine concentrations in children during bronchoscopy with topical anesthesia

To evaluate the safety of topical lidocaine anesthesia in children undergoing bronchoscopy, we determined SLC in 15 children aged 3 months to 9.5 years during flexible fiberoptic bronchoscopy. A total lidocaine dose of 3.2 to 8.5 (mean +/- SEM = 5.7 +/- 0.5) mg/kg was administered to nose, larynx and bronchial tree over 9 to 45 (mean +/- SEM = 20 +/- 2.7) minutes. No complication occurred during the procedure. Peak SLC were 1-3.5 (mean +/- SEM = 2.5 +/- 0.2) micrograms/ml. The Vd beta was 1.79 +/- 0.19 L/kg, the t1/2 beta was 109 +/- 12 minutes, and the total body clearance 12.2 +/- 1.1 ml/min/kg. Peak SLC correlated well with the dose expressed as mg/kg (r = 0.59, p less than 0.025), and even better when related to body surface area (r = 0.63, p less than 0.01). Lidocaine doses up to 8.5 mg/kg proved safe and resulted in therapeutic SLC in our patients. Lidocaine dose up to 7 mg/kg appears to be safe provided that it does not exceed an upper limit of 175 mg/m2 and is gradually administered over a minimum of 15 minutes. Doses of 7-8.5 mg/kg appear to be safe when administered over longer periods.