EMLA in local anaesthesia of the tympanic membrane

Use of Topical Phenol in Awake Young Children for Tympanostomy Tube Placement

Importance: Phenol kits cleared by the Food and Drug Administration (FDA) are indicated as a topical anesthetic for the tympanic membrane (TM) in adults. However, there is no existing literature that reports outcomes to support the safety and use of phenol on the TM of awake children. Objective: Determine if topical phenol is safe and at low risk for complications and therefore be used effectively in awake children to facilitate office otologic procedures as in adults. Design, Setting, and Participants: Children under 21 years of age whose parents agreed to participate in an awake office setting for tympanostomy tube (TT) placement. All children had TT placement after phenol placement on the TM prior to insertion. Main Outcomes and Measures: TM perforation or other signs of TM complications through a minimum of 6-month clinical follow-up, along with assessment of the tolerability of the procedure by the child. Results: A total of 228 children with an age range of 6 months to 15.9 years and 435 TMs completed TT placement using phenol as a local anesthetic while awake in the office. There were no complications reported in the 204 children at the first follow-up visit post TM placement within 3 to 10 weeks. Of the 93 children followed up at least 6 months, there were no TM complications reported. Conclusions: This is the first study to report the outcomes on the use of phenol in an office setting in children. In this large experience, phenol appears to be tolerable and safe for use in young children in the office and is a potential safe choice of topical anesthesia for surgeons if they choose to perform office procedures such as myringotomies or TT placement on children.

Modified Intravenous Cannula Ventilation Tubes for Otic Barotrauma Prevention

Objectives: Middle ear barotrauma is a common complication of hyperbaric oxygen therapy (HBOT). Tympanostomy tube placement prevents barotrauma by facilitating middle ear equalization. We describe variations on techniques published by Mooney et al and Zhang et al for placing modified peripheral intravenous cannula (PIVC) ventilation tubes, which can be performed at the bedside under topical anesthesia. We aim to evaluate the safety and efficacy of this technique when performed to prevent otic barotrauma in patients undergoing HBOT. Methods: We performed an analytical observational study at a tertiary metropolitan Australian hospital with a state-wide adult hyperbaric service between 2018 and 2022. Patients were identified via unit audits. Patient, HBOT, and procedural factors were analyzed against complications using Fisher's exact test with Bonferroni correction and simple logistic regression. Results: Over 4 years, 112 patients (220 ears) underwent modified PIVC ventilation tube insertion. Mean age was 58.6 years (95% CI: 55.7-61.6, SD: 15.9). Thirty-eight patients (33.9%) were female, 74 (66.1%) were male. Thirty-four ears (15.5%) had preexisting barotrauma at the time of tympanostomy tube insertion. Patients underwent a mean of 11.5 dives (95% CI: 9.0-14.0, SD: 13.4), with ventilation tubes being required for a mean of 15.0 days (95% CI: 9.0-14.0, SD: 24.0) to complete HBOT. Fourteen ventilation tubes (6.4%) developed blockage during HBOT, and 12 (5.5%) prematurely extruded. Sixteen ears (7.3%) required reinsertion of ventilation tubes. Nine ears (4.1%) suffered barotrauma despite ventilation tube insertion. Conclusions: Otic barotrauma prophylaxis is paramount for safety during HBOT. We describe a safe, effective, and convenient technique for barotrauma prevention using modified PIVCs.

Topical anesthesia

Topical anesthetics are being widely used in numerous medical and surgical sub-specialties such as anesthesia, ophthalmology, otorhinolaryngology, dentistry, urology, and aesthetic surgery. They cause superficial loss of pain sensation after direct application. Their delivery and effectiveness can be enhanced by using free bases; by increasing the drug concentration, lowering the melting point; by using physical and chemical permeation enhancers and lipid delivery vesicles. Various topical anesthetic agents available for use are eutectic mixture of local anesthetics, ELA-max, lidocaine, epinephrine, tetracaine, bupivanor, 4% tetracaine, benzocaine, proparacaine, Betacaine-LA, topicaine, lidoderm, S-caine patch™ and local anesthetic peel. While using them, careful attention must be paid to their pharmacology, area and duration of application, age and weight of the patients and possible side-effects.

Characterization and comparison of lidocaine-tetracaine and lidocaine-camphor eutectic mixtures based on their crystallization and hydrogen-bonding abilities

Eutectic mixtures formed between active pharmaceutical ingredients and/or excipients provide vast scope for pharmaceutical applications. This study aimed at the exploration of the crystallization abilities of two eutectic mixtures (EM) i.e., lidocaine-tetracaine and lidocaine-camphor (1:1 w/w). Thermogravimetric analysis (TGA) for degradation behavior whereas modulated temperature differential scanning calorimetry (MTDSC) set in first heating, cooling, and second heating cycles, was used to qualitatively analyze the complex exothermic and endothermic thermal transitions. Raman microspectroscopy characterized vibrational information specific to chemical bonds. Prepared EMs were left at room temperature for 24 h to visually examine their crystallization potentials. The degradation of lidocaine, tetracaine, camphor, lidocaine-tetracaine EM, and lidocaine-camphor EM began at 196.56, 163.82, 76.86, 146.01, and 42.72°C, respectively, which indicated that eutectic mixtures are less thermostable compared to their individual components. The MTDSC showed crystallization peaks for lidocaine, tetracaine, and camphor at 31.86, 29.36, and 174.02°C, respectively (n = 3). When studying the eutectic mixture, no crystallization peak was observed in the lidocaine-tetracaine EM, but a lidocaine-camphor EM crystallization peak was present at 18.81°C. Crystallization occurred in lidocaine-camphor EM after being kept at room temperature for 24 h, but not in lidocaine-tetracaine EM. Certain peak shifts were observed in Raman spectra which indicated possible interactions of eutectic mixture components, when a eutectic mixture was formed. We found that if the components forming a eutectic mixture have crystallization peaks close to each other and have sufficient hydrogen-bonding capability, then their eutectic mixture is least likely to crystallize out (as seen in lidocaine-tetracaine EM) or vice versa (lidocaine-camphor EM).

Regional anesthesia for office-based procedures in otorhinolaryngology

Local and topical anesthetic techniques have long been used for office-based procedures in otorhinolaryngology. There are numerous advantages to using local and topical anesthesia for office-based procedures, including a shorter recovery period, decreased health care cost, and the maintenance of a conscious patient who can communicate with the surgeon and maintain his or her own airway during the procedure. In this manuscript, we review the local and topical anesthetic techniques that can be used for otorhinolaryngic procedures including anesthesia of the external face, ear, nose, oral cavity, nasopharynx, oropharynx, hypopharynx, and larynx.

Enhanced Transdermal Delivery of Local Anesthetics by Liposome Formulation of Local Anesthetic Mixture

Various concentrations of either lidocaine or tetracaine, plus combinations of lidocaine and tetracaine were formulated into liposomes to improve topical anesthesia. The topical anesthetic effects of these liposomal mixtures of local anesthetics (Lipo-MLA) were then compared with those of EMLA (Eutectic Mixture of Local Anesthetics) and single local anesthetic liposomes using a pinprick test on healthy adult volunteers. The Lipo-MLA exhibited significantly improved anesthetic effects compared to the EMLA and single local anesthetic liposomes with a faster onset time of approximately thirty minutes and duration of at least four hours. A dermal toxicity study using rats revealed that Lipo-MLA was safe at greater than 2,000 mg/kg bodyweight.

Efficacy of a eutectic mixture of local anesthetics as a topical anesthetic in minor otologic procedures

A eutectic mixture of local anesthetics (EMLA), prepared as a cream, is an oil-in-water emulsion of 2 anesthetic agents lidocaine and prilocaine. Several clinical applications of EMLA cream, its effectiveness as a topical anesthetic, and its safety profile have been previously reported. We report our experience with EMLA cream in 17 adult and 24 pediatric patients. We find EMLA to be the preferred anesthetic for performing minor outpatient otologic procedures in adults. We also find EMLA to be a safe, well-tolerated alternative to general anesthesia in some pediatric patients. Potential cost savings of EMLA cream during pediatric myringotomies in the clinic are also discussed.

Short-term tympanostomy in conjunction with hyperbaric oxygen therapy

OBJECTIVE

To determine the most effective method of short-term middle ear aeration in patients unable to tolerate hyperbaric oxygen (HBO) therapy.

STUDY DESIGN

Prospective study comparing two methods of short-term tympanostomy in each patient.

METHODS

Seventeen adult patients were referred for management of barotitis and inability to tolerate hyperbaric oxygen therapy (HBO). Each patient underwent CO2 laser tympanostomy on the right ear and tympanostomy with T-tube placement in the left ear. The tube was removed on completion of HBO. Patients were asked to rate pain and their satisfaction with each method of tympanostomy using a visual analog scale. Otorrhea, persistent perforation, recurrent barotitis, hearing loss, and otalgia occurring during the study period were documented.

RESULTS

Laser tympanostomy was associated with a significantly lower incidence of otorrhea but was attended by recurrent barotitis in four of 16 patients. Laser tympanostomy was perceived as being less painful and was rated higher in overall satisfaction.

CONCLUSIONS

Laser tympanostomy is an effective method for management of barotitis in patients unable to tolerate HBO. Otorrhea is significantly reduced, although a risk of recurrent barotitis exists if the laser perforation closes prior to completion of HBO. Both methods of short-term tympanostomy reduce complications when compared with a retrospective cohort.

Effective anaesthesia for transtympanic electrocochleography

The objective of this study was to quantify the anaesthetic effect of EMLA cream during transtympanic electrocochleography (TTECochG) and thereby to determine if the application of EMLA should be recommended in routine practice of electrocochleography (ECochG). ECochG provides useful information in patients with inner ear fluid disorders. A major concern regarding transtympanic positioning of the electrode in ECochG is patient discomfort. Previous work has suggested that EMLA cream may make this technique more tolerable to patients. A prospective randomized study was performed evaluating the discomfort associated with unilateral TTECochG in a group where EMLA cream was used to anaesthesize the tympanic membrane (n = 24), and in a group where no anaesthesia was used (n = 22). A statistically significant difference was evident between the discomfort ratings of the groups (P < 0.0001, Mann-Whitney U test), the discomfort being greater in the no anaesthesia group. EMLA cream has thus been shown to alleviate the level of discomfort associated with TTECochG and so to be an acceptable modification of this technique.

Use of EMLA cream in the treatment of post-herpetic neuralgia

EMLA cream is an acronym for eutectic mixture of local anesthetics. It contains lidocaine and prilocaine creams. A eutectic preparation, applied topically, penetrates into the dermis after an application period of 1 to 2 hours. This case report describes the successful treatment with EMLA cream of post-herpetic neuralgia, which was resistant to other modes of therapy, and briefly discusses the pharmacology of EMLA cream.

Eutectic lidocaine/prilocaine cream. A review of the topical anaesthetic/analgesic efficacy of a eutectic mixture of local anaesthetics (EMLA)

Eutectic lidocaine/prilocaine cream 5% is a eutectic mixture of the local anaesthetics lidocaine (lignocaine) 25 mg/g and prilocaine 25 mg/g that provides dermal anaesthesia/analgesia following topical application. The principal indication in which eutectic lidocaine/prilocaine cream has been studied is the management of pain associated with venipuncture or intravenous cannulation, where significantly greater pain relief than placebo, with equivalent efficacy to ethyl chloride spray and lidocaine infiltration, has been demonstrated. In dermatological surgery, eutectic lidocaine/prilocaine cream offers effective pain relief in children undergoing curettage of molluscum contagiosum lesions, and in adults undergoing split-skin graft harvesting. Particular benefit has also been shown with use of eutectic lidocaine/prilocaine cream in association with treatment of condylomata acuminata in both men and women, and it appears to provide a useful alternative to lidocaine infiltration in this context. Further research in such indications as paediatric lumbar puncture, minor otological surgery, and minor gynaecological, urological and andrological procedures is likely to further broaden the profile of clinical use for eutectic lidocaine/prilocaine cream. Eutectic lidocaine/prilocaine cream has a very favourable tolerability profile, transient and mild skin blanching and erythema being the most frequent adverse events to occur in association with its application to skin. The potential for inducing methaemoglobinaemia, attributed to a metabolite of the prilocaine component of the formulation, prohibits its use in infants younger than 6 months. In summary, eutectic lidocaine/prilocaine cream is a novel formulation of local anaesthetics that has proven to be effective and well-tolerated in the relief of pain associated with various minor interventions in adults and children.