Allergy to local anaesthetics in dentistry. Myth or reality?

Knowledge and attitudes toward anaphylaxis to local anesthetics in dental practice

OBJECTIVE/AIM

The absence of a comprehensive understanding of potential anaphylactic reactions to local anesthetics (LAs) and management can result in grave consequences. For this reason we aim to assess Latin American dentists' knowledge, preparedness, and competency in managing anaphylactic reactions to LAs.

MATERIALS AND METHODS

Design: A cross-sectional study was conducted from November 2021 to February 2022. Board-certified dentists answered a survey comprising 26 structured questions. Chi-square tests and logistic regression models were performed in Stata 17.0.

SETTING

Argentina, Brazil, Colombia, Costa Rica, Ecuador, Honduras, Mexico, Peru, Venezuela, and other Latin American countries.

RESULTS

Of 507 respondents, lidocaine was the most frequently used LA (88.1%). While 85.2% could identify dyspnea as a symptom of anaphylaxis, only 50.1% knew the correct route for epinephrine administration, and just 43.5% had epinephrine in their emergency kits. Confidence in managing anaphylactic reactions was low (9.6%). Older age was inversely related to both knowledge of anaphylaxis management and the possession of epinephrine (P = 0.003 and P = 0.0001, respectively).

DISCUSSION

Our study highlights a concerning discrepancy between the practical readiness of Latin American dentists in handling anaphylaxis.

CONCLUSION

The study's findings underscore the need for educational interventions to improve the readiness to identify and handle anaphylactic emergencies in dental practice.

Factors associated with transient bradycardia during local anesthesia administration to the oral cavity under intravenous sedation: A retrospective cohort study

Background/purpose

The possibility of triggering the trigeminocardiac reflex (TCR) during oral surgery is considerably lower than that during other surgeries. A reduced heart rate (HR) of ≥20% from baseline is usually considered a diagnostical criterion for the TCR. Our automated anesthesia charting system often revealed cases of slight transient HR decrease during sedation. We aimed to explore its incidence and associated factors during local anesthesia administration under intravenous sedation.

Materials and methods

This study analyzed the data of 2636 cases that received infiltration anesthesia under intravenous sedation from 2008 to 2010 and had vital signs recorded using an automated anesthesia charting system. Especially, data concerning the average HR before anesthesia and the minimum HR between the initiation and end of anesthesia from anesthetic records were extracted. Moreover, data regarding patients' medical history and unusual reactions during dental treatment were collected. Multivariate logistic regression analysis was performed to identify factors associated with transient bradycardia (TB).

Results

TB occurred in 472 patients (17.9%); no patient developed hypotension or any associated symptoms, suggesting that intravenous sedation was effective in stabilizing vital signs. The factors associated with TB were younger age, gag reflex, and allergy to local anesthetics. There were no differences in sex, patient history, or dose of sedatives between patients with TB and those without TB.

Conclusion

The incidence of TB during infiltration anesthesia under sedation was found to be higher than that previously reported. Additionally, young age and gag reflex were identified as factors associated with bradycardia development.

Knowledge, Practice and Self-Reported Confidence Level of Croatian Dentists in the Use of Local Anesthesia: A Cross-Sectional Study

Objectives: To provide safe and effective local anesthesia, dentists must have knowledge of neuroanatomy, anesthesia agents, techniques, equipment, and proper use of local anesthetics. This study aims to explore the knowledge, practices, and confidence regarding local anesthetics and anesthetic techniques in dentistry. Material and Methods: The online cross-sectional questionnaire was conducted via social media, and yielded 441 responses from across the country (69.8% women and 30.2% men; 70.7% general dentists; and 29.3 specialists). The data collected included sociodemographic characteristics, knowledge, and practices pertaining to the usage of local anesthesia. The questionnaire also documents their self-assessed confidence level in applying different local anesthetic techniques and experiences with adverse reactions. The obtained data were processed by description and using a generalized linear model for regression. Results: The respondents had a median knowledge score of 6 out of a possible 14 points regarding local anesthetics in dental medicine, and their median self-confidence level in the successful application of various techniques of local anesthesia was 54 out of a maximum of 85 points. The results showed that a higher knowledge level was associated with the female gender (OR 1.83, CI 1.13-2.98, p = 0.014) and specialization in oral surgery (OR 7.04, CI 1.71-29.07, p = 0.007). In contrast, a lack of confidence in using various local anesthetic techniques was also associated with the female gender (OR 0.63, CI 0.41-0.99, p = 0.047) and specialization in orthodontics (OR 0.16, CI 0.03-0.88, p = 0.035). Of the respondents, 81.4% (n = 371) experienced a local complication, and 42.2% (n = 186) experienced a systemic complication during local anesthesia. The complications experienced cannot be associated with a lack of knowledge or self-confidence (p > 0.05). The majority of respondents (364 of the 441 total-82.5%) expressed interest in receiving further education on the topic of local anesthesia. Conclusions: The research results show that the dentists involved in the study have poor knowledge of local anesthetics and moderate self-reported confidence levels in using various local anesthetic techniques. Moreover, dentists' self-confidence in applying different techniques of local anesthesia is not related to their knowledge. Therefore, it would be necessary for dentists to undergo a continuing dental education program that enables them to enhance their skills and knowledge in local anesthesia.

Allergy to Local Anesthetics is a Rarity: Review of Diagnostics and Strategies for Clinical Management

Local anesthetics (LA) are commonly used in procedures and in topical agents for pain management. With the increasing use of LA drugs, the management of LA reactions is more frequently encountered in the office and in operating rooms. True allergic reactions involving IgE-mediated reactions and anaphylaxis are rare; they have only been identified in case reports and account for less than 1% of adverse LA reactions. Most reactions are non-allergic or are a result of hypersensitivity to other culprits such as preservatives, excipients, or other exposures. LA reactions that are misclassified as true allergies can lead to unnecessary avoidance of LA drugs or delays in surgical procedures that require their use. A detailed history of prior LA reactions is the first and most crucial step for understanding the nature of the reaction. Reactions that are suspicious for an immediate hypersensitivity reaction can be evaluated with skin prick and intradermal testing with subsequent graded challenge. Reactions that are suspicious for a delayed hypersensitivity reaction can be evaluated with patch testing.

Wide-Awake Olecranon Fracture Fixation: Is it Possible?

Purpose

The wide-awake local anesthesia no tourniquet technique has been widely performed in hand and wrist surgery with remarkable results. However, its use on the elbow has rarely been reported. Here we describe the use of wide-awake local anesthesia no tourniquet in olecranon fracture fixation in 4 cases.

Methods

Tumescent anesthesia was injected from the proximal ulna to approximately 10 cm distally and into the periosteum and fracture site, approximately 25 minutes before skin incision. The fracture underwent closed reduction and was fixed using a long 6.5-mm cancellous screw with a washer through a small incision. No tourniquet was applied and none or mild sedation was administered. At the end of the operation, patients were asked to perform active elbow flexion-extension and forearm pronosupination movements under an image intensifier to test the range of motion and fracture stability.

Results

The surgical procedure was completed in all 4 cases. Two patients reported mild pain during ulnar medullary canal reaming, with pain scores of 3 and 4 on a 10-point scale, respectively. One case was resolved with additional local anesthetic injection. The other case required the administration of intravenous propofol. Both patients were able to actively move the elbow at the end of the operation.

Conclusions

The use of wide-awake local anesthesia no tourniquet for olecranon fracture fixation has the advantage of obviating the need for an arm tourniquet, general anesthesia or heavy sedation, preoperative tests, and discontinuing routine medications (including anticoagulants). The stability of the elbow fixation was tested by active motion during surgery. This simple, safe, low-cost, and reproducible technique may be a good option for patients with contraindications or high risk of general or regional nerve block anesthesia.

Type of study/level of evidence

Therapeutic IV.

Cardiac arrest in a 36 year-old after trigger point injection with lidocaine: Case report

A typical vasovagal response is characterized by bradycardia and paradoxical vasodilation. It is oftentimes self-limited and spontaneously reversible; however, severe cases can result in significant complications. This report describes a case of profound vasovagal syncope with subsequent cardiac arrest in the setting of receiving a trigger point injection. This patient presented to an outpatient clinic for ultrasound-guided left trapezius, levator scapulae, and rhomboid trigger point injections for relief of myofascial pain. One milliliter of 1% lidocaine was injected into the first trigger point when she stated she felt dizzy before becoming unresponsive without palpable peripheral pulses. The patient regained consciousness following cardiopulmonary resuscitation (CPR). Considering the frequency of office based pain procedures, it is important to recognize the potential serious complications associated with procedures frequently thought to be benign.

Syncope in Dental Practices: A Systematic Review on Aetiology and Management

INTRODUCTION

This systematic review aimed to give an overview of the current evidence surrounding the aetiology and management in terms of treatment and prevention of syncope in dental practices. Alongside the occurrence, the practitioner's competence, and the association between syncope and local anaesthetics were discussed.

METHODS

An electronic search in EMBASE, Web of Science, PubMed, Cochrane databases and a hand search were performed by 2 independent reviewers to identify studies up to November 2019. Eligibility criteria were applied and relevant data was extracted. Inclusion criteria covered all types of dental treatment under local anaesthesia or conscious sedation performed by a wide range of oral health care workers in their practices. Risk of bias of the included studies was assessed using the methodological tools recommend by Zeng et al.¹ No restrictions were made to exclude papers from qualitive analysis based on risk of bias assessment.

RESULTS

The search yielded a total of 18 studies for qualitative analysis. With the exception of one prospective cohort study, all articles were considered having a high risk of bias. Meta-analysis showed that dentists encountered on average 1.2 cases of syncope per year. The male gender (RR = 2.69 [1.03, 7.02]), dental fear (RR = 3.55 [2.22, 5.70]), refusal of local anaesthesia in non-acute situations (OR = 12.9) and the use of premedication (RR = 4.70, [1.30, 16.90]) increased the risk for syncope. Treatment and prevention were underreported as both were solely discussed in one study. The supine recovery position with raised legs and oxygen administration (15l/min) was presented as an effective treatment. The Medical Risk-Related History (MRRH) system was proposed as prevention protocol, yet this protocol was ineffective in reducing incidence rates (p = 0.27). The majority of dentists (79.2%) were able to diagnose syncope, yet most (86%) lacked the skills for appropriate treatment. Only 57,6% of dental practices were equipped with an oxygen cylinder.

CONCLUSIONS

Syncope is the most common emergency in dental practices. Nonetheless, the vast majority of dentists do not seem competent nor prepared to manage this emergency. Psychogenic factors seem to play an important role in provoking syncope. Placing the patient in a supine reclined position with raised legs in combination with the administration of oxygen seems effective for regaining consciousness. Although valuable in many aspects, risk assessment by medical history taking is not proven to result in fewer episodes. The strength of these conclusions is low based on GRADE guidelines.².

Management of anaphylaxis in the dental practice: an update

Anaphylaxis is a severe and potentially life-threatening allergic reaction that can occur in the dental practice. There are a number of dental-related causes including mouthwashes, local anaesthetics, latex and antibiotics. The dental team must be able to respond effectively and manage the life-threatening situation appropriately following Resuscitation Council UK guidelines. The timely administration of adrenaline is life-saving; any delays can lead to a poor outcome. With the current national supply issues with adrenaline auto-injector devices, there is an expectation that GDPs should be competent at drawing up adrenaline from an ampoule and administrating it intramuscularly. The aim of this article is to provide an update on the management of anaphylaxis in the dental practice with particular reference to the procedure for intramuscular injection of adrenaline.

Anaphylactic reaction after local lidocaine infiltration for retraction of retained teeth

Although allergic reactions are not rare complications in drug use, anaphylaxis or anaphylactoid reactions to some widely used drugs can embarrass clinicians because anaphylaxis is not easily diagnosed at the time of the event and treatment is unfamiliar to many. Lidocaine is a very popular drug in dental procedures and anaphylactoid reaction to it has been rarely reported. Clinicians who use lidocaine daily should, however, be aware of the possibility of anaphylaxis after its use. Once it occurs, anaphylaxis can be fatal, but if it is quickly diagnosed or suspected, treatment is simpler than most clinicians believe. An 86-year-old woman experienced an anaphylactic reaction 30 min after local infiltration of lidocaine for retraction of retained teeth. The dentist called an anesthesiologist for assistance. Fortunately, an anaphylactic reaction was quickly suspected and after subsequent rapid treatment with the administration of fluid and drug therapy, the patient recovered completely.

Twenty Years' Experience with Anaphylaxis-Like Reactions to Local Anesthetics: Genuine Allergy is Rare

BACKGROUND

Anaphylaxis-like reactions occur within minutes after the application of local anesthetics (LA), most commonly during dental interventions. Impressive symptoms including respiratory distress or loss of consciousness frequently give rise to a suspicion of allergy and may prompt patients and treating physicians to refuse future LA injections.

OBJECTIVE

Nonallergic mechanisms are responsible for the majority of LA-induced immediate-type reactions. In view of the preponderance of nonallergic reactions, the question arises whether genuine LA allergy may be missed during routine testing procedures.

METHODS

We retrospectively evaluated clinical data and test results from patients referred to our allergy clinic within the past 20 years for diagnostic workup of LA-induced immediate-type reactions.

RESULTS

Of 402 evaluated patients, 29 had an episode of acute urticaria within 30 minutes after LA injections, and the remaining 373 had a history of mainly subjective cutaneous, respiratory, cardiovascular, and neurological complaints. Of the patients reporting urticaria with or without angioedema, 14 were diagnosed with a spontaneous episode of urticaria, 13 had allergic or nonallergic reactions to other agents, and 2 had IgE-mediated LA allergy. LA allergy was definitely excluded by 771 subcutaneous provocation tests with skin test negative LA, thereby demonstrating the high predictive value of negative intradermal testing.

CONCLUSIONS

Skin testing and provocative LA challenge are useful to exclude LA allergy, and this testing procedure seems to be appropriate to identify the extremely rare cases with IgE-mediated LA allergy.

Cocaine Allergy in Drug-Dependent Patients and Allergic People

BACKGROUND

Adverse reactions to local anesthetics (LAs), especially esters, are not uncommon, but true allergy is rarely diagnosed. To our knowledge, currently there is no reliable method of determining IgE-mediated hypersensitivity to LAs and cocaine.

OBJECTIVE

To assess the clinical value of allergy tests (prick, IgE, challenges, and arrays) in people suffering hypersensitivity reactions (asthma and anaphylaxis) during local anesthesia with cocaine derivatives and drug abusers with allergic symptoms after cocaine inhalation.

METHODS

We selected cocaine-dependent patients and allergic patients who suffered severe reactions during local anesthesia from a database of 23,873 patients. The diagnostic yield (sensitivity, specificity, and predictive value) of allergy tests using cocaine and coca leaf extracts in determining cocaine allergy was assessed, taking a positive challenge as the criterion standard.

RESULTS

After prick tests, specific IgE, and challenge with cocaine extract, 41 of 211 patients (19.4%) were diagnosed as sensitized to cocaine. Prick tests and IgE to coca leaves (coca tea) had a good sensitivity (95.1% and 92.7%, respectively) and specificity (92.3 and 98.8%, respectively) for the diagnosis of cocaine allergy and LA-derived allergy.

CONCLUSIONS

Cocaine may be an important allergen. Drug abusers and patients sensitized to local anesthesia and tobacco are at risk. Both prick tests and specific IgE against coca leaf extract detected sensitization to cocaine. The highest levels were related to severe clinical profiles.

No cases of perioperative allergy to local anaesthetics in the Danish Anaesthesia Allergy Centre

BACKGROUND

Local anaesthetics (LA) are often suspected as possible causes of allergic reactions. The Danish Anaesthesia Allergy Centre (DAAC) is the national reference centre for investigation of perioperative allergic reactions. The purpose of this study was to investigate the incidence of IgE-mediated immediate type perioperative allergic reactions to LA.

METHODS

In the period 2004-2013, a total of 409 patients (244 women/165 men; median age 49 years, range 1-86 years) were investigated in DAAC on suspicion of allergy associated with anaesthesia and surgery. A total of 162 (40%) patients were exposed to one or more LA. Suspected allergy to LA was investigated by prick test, intradermal test and subcutaneous provocation with the suspected drug. Patients with positive skin tests still underwent subcutaneous provocation, as false positive skin tests can occur.

RESULTS

A total of 203 test series with LA were carried out on 162 patients (89 women/73 men; mean age 49 years, range 2-85 years) with the following drugs: Lidocaine n = 80 (49%), bupivacaine n = 82 (51%), ropivacaine n = 31 (19%) and mepivacaine n = 10 (6%). All 162 patients had negative subcutaneous provocation for all tested LA (95% CI: 0-1.8%). Investigations revealed another allergen in 52 of 162 patients.

CONCLUSION

None of the 162 patients with suspected perioperative allergic reactions and exposure to LA reacted on subcutaneous provocation with the relevant LA. Thus, no patients have been diagnosed with allergy to LA in DAAC in the period 2004-2013 and allergy to LA must be considered very rare in this population.

Allergic Reactions to Dental Materials-A Systematic Review

INTRODUCTION

Utility of various dental materials ranging from diagnosis to rehabilitation for the management of oral diseases are not devoid of posing a potential risk of inducing allergic reactions to the patient, technician and dentist. This review aims to develop a systematic approach for the selection and monitoring of dental materials available in the market thereby giving an insight to predict their risk of inducing allergic reactions.

MATERIALS AND METHODS

Our data included 71 relevant articles which included 60 case reports, 8 prospective studies and 3 retrospective studies. The source of these articles was Pub Med search done with the following terms: allergies to impression materials, sodium hypochlorite, Ledermix paste, zinc oxide eugenol, formaldehyde, Latex gloves, Methyl methacrylate, fissure sealant, composites, mercury, Nickel-chromium, Titanium, polishing paste and local anaesthesia. All the relevant articles and their references were analysed. The clinical manifestations of allergy to different dental materials based on different case reports were reviewed.

RESULTS

After reviewing the literature, we found that the dental material reported to cause most adverse reactions in patients is amalgam and the incidence of oral lichenoid reactions adjacent to amalgam restorations occur more often than other dental materials.

CONCLUSION

The most common allergic reactions in dental staff are allergies to latex, acrylates and formaldehyde. While polymethylmethacrylates and latex trigger delayed hypersensitivity reactions, sodium metabisulphite and nickel cause immediate reactions. Over the last few years, due to the rise in number of patients with allergies from different materials, the practicing dentists should have knowledge about documented allergies to known materials and thus avoid such allergic manifestations in the dental clinic.

Study on patients who underwent suspected diagnosis of allergy to amide-type local anesthetic agents by the leukocyte migration test

BACKGROUND

There are problems in diagnosis of allergy to amide-type local anesthetic agents (ALAs), because definitive diagnosis is not obtained by in vivo tests, which are used for the diagnosis. Consequently, patients may be exposed to risk. There are few diagnoses based on in vitro tests, and there are almost no relevant studies.

METHODS

Authors examined involvement of allergic reaction using the leukocyte migration test (LMT) through multiple standpoints in 43 patients who underwent suspected diagnosis of allergy to ALAs.

RESULTS

Rate of LMT-positives was 54%, and especially the positive rate of lidocaine hydrochloride preparations was significantly high. In 15 positives to lidocaine hydrochloride preparations, all cases were indicated as positive in a test with drugs containing antiseptic agent, but only 3 cases were indicated as positive in a test with lidocaine hydrochloride alone. In addition, test with paraben was conducted in 4 cases; 2 cases were confirmed as positive. In relevance of histories of drug or food allergies, development rates of ALAs-allergies were the highest in both allergies, and were 35% and 13%, respectively.

CONCLUSIONS

There is a high possibility that these adverse reactions were caused by pseudoallergy to drug. Even by allergic reactions, it was assumed that 80% of them might be caused by antiseptic agents such as paraben. In addition, it was suggested that ALAs, especially lidocaine hydrochloride preparations have high antigenicity (sensitizing property). Furthermore, it was considered that patients with past history of drug or food allergies have a high potential for manifestation of the reactions.

Local anesthetics injection therapy for musculoskeletal disorders: a systematic review and meta-analysis

OBJECTIVES

Therapeutic injections with local anesthetics (TLA) are widespread and are used for various symptoms of the musculoskeletal system. The aim of the present project was to evaluate the efficacy and safety of TLA in the treatment of musculoskeletal disorders.

METHODS

Systematic literature search for controlled clinical trials (Medline, Cochrane, CAMbase, hand search of references) without language limitation; independent screening of the search results (n=3200 hits), abstract reading, and full-text analysis by 2 reviewers. Two authors independently extracted the data and assessed study quality. Meta-analysis was calculated for studies using a continuous scale for pain assessment.

RESULTS

Twenty-four controlled trials were included in this review. In almost all studies no primary outcome measure was defined and the overall study quality was low. The qualitative data analysis revealed no clear trend for or against TLA. The meta-analysis of 12 studies showed no significant difference in pain reduction for TLA compared with control treatments consisting of saline injections or other substances, oral analgesics, or nonpharmacological interventions (standardized mean difference -0.31, 95% confidence interval, -0.75 to 0.14). Minor adverse side effects were reported in 7 studies in both the TLA and the control groups with no trend for one of the groups to be safer.

DISCUSSION

Despite the widespread use of TLA for musculoskeletal disorders in daily practice, available data are sparse and of low quality and, therefore, do not allow a final recommendation. High-quality studies are needed to close the gap between common practice and research.

IgE-mediated allergy to local anaesthetics: separating fact from perception: a UK perspective

Local anaesthetic (LA) agents have been routinely used in dentistry, ophthalmology, minor surgery, and obstetrics since the late nineteenth century. Reports relating to adverse reactions and LA allergy have appeared in the published literature for several years. However, the incidence of true, IgE-mediated LA allergy remains uncertain and is presumed to be very low. We critically reviewed the English language literature on suspected LA allergy and its investigation with the aim of estimating the reported prevalence and analysing the role of different tests currently used to identify and confirm LA allergy. Twenty-three case series involving 2978 patients were identified and analysed. Twenty-nine of these patients had true IgE-mediated allergy to LA, thus confirming the reported prevalence of LA allergy in large series to be <1% (0.97%). The protocols used in the investigation of these patients have also been discussed. Evidence from this review confirms the rarity of IgE-mediated allergy to LA and supports an investigation strategy based on using the clinical history to select patients for skin testing and challenge. We believe that such a triage process would alleviate pressures on allergy services without compromising patient safety.

Efficacy of 4 % Articaine and 2 % Lidocaine: A clinical study

OBJECTIVES

This study was undertaken to compare the anesthetic properties of 4 % Articaine hydrochloride and 2 % Lidocaine both with 1:100,000 epinephrine for mandibular inferior alveolar nerve anesthesia.

MATERIALS AND METHODS

Thirty healthy patients were included in this randomized double-blind clinical cross over study. Each subject received each test solution at different times. Inferior alveolar nerve block anesthesia was used for extraction of bilateral impacted mandibular third molar on different occassions. The time of onset of action, duration of anesthesia, efficacy of anesthesia, hemodynamic parameters and oxygen saturation were monitored during the procedure. A visual analog scale was used to assess pain during surgery, and thus subjectively evaluate the anesthetic efficacy of the two solutions.

RESULTS

No statistically significant differences were seen in the onset and duration of anesthesia between the Articaine and Lidocaine solutions.

CONCLUSIONS

4 % Articaine offers better clinical performance than 2 % Lidocaine, particularly in terms of latency and duration of the anesthetic effect. However, no statistically significant differences in anesthetic efficacy were recorded between the two solutions.

Life-threatening anaphylactic reaction after the administration of airway topical lidocaine

A 9-year-old boy who developed a life-threatening anaphylaxis reaction of the airway and subsequent dyspnea and circulation collapse because of instilled the topical lidocaine into the airway within 2 min before performing flexible bronchoscopy (FB). FB revealed swollen airway mucosa and extensive foamy secretion that severely compromised the ventilation lumen. Rapid detection with FB and immediate resuscitation, including prompt administration of epinephrine, volume expander, and positive pressure ventilation with pure oxygen via an endotracheal tube, were successfully save the patient's life.

Effect of PaCO2 and PaO2 on lidocaine and articaine toxicity

Alterations in arterial PaCO₂ can influence local anesthetic toxicity. The objective of this study was to evaluate the effect of stress-induced changes in PaCO₂ and PaO₂ on the seizure threshold of lidocaine and articaine. Lidocaine (2% with 1 : 100,000 epinephrine) or articaine (4% with 1 : 100,000 epinephrine) was administered intravenously under rest or stress conditions to 36 rats separated into 4 groups. Propranolol and prazosin were administered preoperatively to minimize cardiovascular effects of epinephrine. Mean arterial pressure (MAP), heart rate (HR), and arterial pH, PaCO₂, and PaO₂ were measured. Results showed no differences in MAP, HR, or pH. Stress significantly increased the latency period for the first tonic-clonic seizure induced by a toxic dose of both lidocaine and articaine (P < .05). Seizures were brought on more rapidly by articaine. No significant difference between toxic doses of lidocaine and articaine was noted. Stress raised the seizure threshold dose for both drugs and significantly (P < .01) increased arterial PaO₂ from 94.0 ± 1.90 mm Hg to 113.0 ± 2.20 mm Hg, and reduced PaCO₂ from 36.0 ± 0.77 mm Hg to 27.0 ± 0.98 mm Hg. In conclusion, reduction in PaCO₂ and/or increase in PaO₂ raised the seizure threshold of lidocaine and articaine. This study also confirmed that lidocaine and articaine have equipotent central nervous system toxicity.

Provocation tests in drug hypersensitivity

Provocation tests are regarded as the "gold standard" to establish or exclude the presence of hypersensitivity to a certain drugs because they reproduce not only allergy symptoms but other adverse manifestations, irrespective of their pathomechanism. Provocation testing is potentially harmful and should be considered only after balancing the risk-benefit ratio in the individual patient. The reasons for false-positive and false-negative results are numerous, including loss of sensitization, cofactors not being included in the diagnostic procedure, and the potential induction of tolerance during provocation. When conducted by experienced clinicians in a carefully monitored setting, however, drug provocation testing is a safe method to confirm or exclude drug hypersensitivity.

Approach to patients with suspected hypersensitivity to local anesthetics

Adverse reactions to local anesthetics are relatively common, but true IgE-mediated hypersensitivity is extremely rare. Fortunately, the vast majority of adverse reactions occur via nonimmunologic means, but considerable confusion still exists among providers. We conducted a review of the literature to determine if earlier estimates of IgE-mediated allergy are consistent with current reports and whether current management strategies are consistent with these findings. We identified several confounding variables involved in the evaluation, including the roles of preservatives/additives, epinephrine, latex, and inadequate testing procedures. These problems may cause significant diagnostic challenges for clinicians. It is in fact much more likely that there is an alternate diagnosis, and in many cases clinicians can begin the evaluation in the office. When local anesthetic allergy is still suspected, the patient should be referred to an allergist for testing to determine if the suspected culprit drug can be safely used, or, if necessary, identify a suitable alternative.

Angioedema of the airway: an unusual case

We report a case of angioedema caused by angiotensin-converting enzyme inhibitor and topical lignocaine spray, administered during nasendoscopy.

Angioedema induced by angiotensin-converting enzyme inhibitors is a rare but well known entity. Allergy to topical lignocaine has been acknowledged as a rare phenomenon when used for dental surgery and for skin anaesthesia, but it has not previously been reported after topical administration prior to nasendoscopy. In the reported case, our patient was unfortunate enough to be allergic to both lisinopril and lignocaine. The result was life-threatening airway obstruction, and the continued use of lignocaine spray sustained the laryngeal oedema. We advise that patients are asked about any and every allergy – specifically, any previous problems with dental procedures – before administration of local anaesthetic spray to the upper aerodigestive tract.

Anaphylaxis during anaesthesia: diagnostic approach

Correct management of anaphylaxis during anaesthesia requires a multidisciplinary approach with prompt recognition and treatment of the acute event by the attending anaesthesiologist, and subsequent determination of the responsible agent(s) with strict avoidance of subsequent administration of all incriminated and/or cross-reacting compounds. However, correct identification of the causative compound(s) and safe alternatives is not always straightforward and, too often, not done. This review is not intended to discuss acute management of anaesthesia-related anaphylaxis but summarizes the major causes of anaphylaxis during anaesthesia and the diagnostic approach of this rare but potentially life-threatening complication. Apart from general principles about the diagnostic approach, history taking and importance of tryptase quantification, more specific confirmatory diagnostic procedures are organized on the basis of the major causes of perioperative anaphylactic reactions.