Cardiopulmonary arrest due to misuse of viscous lidocaine

A 30-month-old female infant had a cardiopulmonary arrest due to viscous lidocaine. The protective airway mechanisms were blunted by this drug, resulting in aspiration, hypoxia, seizures, and death. Lidocaine has also been associated with respiratory depression, psychosis, methemoglobinemia, and toxic cardiovascular reactions. We do not recommend the use of viscous lidocaine for minor oral irritation in infants and young children.     

Ropivacaine compared to lidocaine for tonsillectomy under local anaesthesia

The aim of the present study was to investigate the safety and efficacy of ropivacaine compared to lidocaine for tonsillectomy under local anaesthesia. During the last 2 years, 77 patients undergoing tonsillectomy under local anaesthesia in the seated position were randomised to receive ropivacaine or lidocaine. The following parameters were recorded: time to surgical anaesthesia, the duration of the procedure, postoperative pain, the need for analgesics during the first 10 h after surgery, cardiac arrhythmias, the occurrence of allergic reaction and larynx spasm. It took significantly longer to reach surgical anaesthesia in the ropivacaine patients (8.3+/-1.3 min versus 2.7+/-0.8 min.), but the pain immediately following the procedure was significantly lower (1.0+/-0.4 versus 2.6+/-1.0). Adjuvant analgetics were administered later and in significantly lower doses in the ropivacaine patients. There were no adverse reactions. In conclusion, ropivacaine in local tonsillectomy is safe, has a longer onset-time, but is more efficient concerning postoperative pain than lidocaine.     

利多卡因雾化吸入麻醉在频闪喉镜检查中的应用

目的观察利多卡因雾化吸入咽喉表面麻醉在频闪喉镜检查中的应用价值。方法应用前瞻性随机对照研究的方法,比较2%利多卡因雾化吸入咽喉表面麻醉和1%丁卡因喷雾咽喉表面麻醉在频闪喉镜检查时的麻醉效果。结果 218例初次行频闪喉镜检查的患者中,1%丁卡因喷雾咽喉部黏膜表面麻醉组患者对麻醉不适和频闪喉镜检查不适的VAS评分分别为1.02±1.83和1.10±1.69,而2%利多卡因雾化吸入咽喉黏膜表面麻醉组的分别为0.61±1.67和1.66±2.63,两组之间统计学上无显著差异（P〉0.05）,对22例复诊的患者第1次行1%丁卡因喷雾咽喉部黏膜表面麻醉,本次行2%利多卡因雾化吸入咽喉表面麻醉,其麻醉不适及检查不适的视觉模拟评分（visualanaloguescale,VAS）分值与第1次行1%丁卡因喷雾咽喉部黏膜表面麻醉时的分值无统计学差异（P〉0.05）。结论频闪喉镜检查应用2%利多卡因雾化吸入表面麻醉的方法简单、易行,效果不逊于常规1%丁卡因喷雾表面麻醉,值得推广应用。     

Inner ear lidocaine concentrations following iontophoresis

This study has established the feasibility of measuring perilymph lidocaine levels after iontophoresis for local tympanic anesthesia in the rabbit model. A subsequent study may now be performed to produce a valid, dose-response curve correlating perilymph lidocaine levels and cochlear responses. In this manner the effects of and safety of lidocaine iontophoresis for tympanic anesthesia can be determined with certainty. After intravenous sedation, eight rabbits underwent iontophoresis followed by diagnostic vestibulotomies. Perilymph samples were taken and analyzed for lidocaine levels. Significant amounts of perilymph lidocaine were found in both the intact and perforated tympanic membrane groups. In the perforated tympanic membrane group, the perilymph lidocaine level was eight times that of the intact tympanic membrane group. Future studies to determine the dose-response relationship of perilymph lidocaine to cochlear responses are now possible. Thus, the safety of lidocaine iontophoresis and the degree of inner ear toxicity of lidocaine can be established quantitatively.     

利用微透析技术对利多卡因治疗耳鸣作用机制的实验研究

目的　探讨利多卡因治疗耳鸣的神经递质学方面的机制。方法　利用微透析技术和微柱高效液相电化学检测方法研究利多卡因对耳鸣动物模型下丘和颞皮层 5 羟色胺 (5 hydroxytryptamine,5 HT)神经递质的影响。结果　 2 6只白色Wistar大鼠水杨酸钠造模耳鸣 ,显示下丘和颞皮层部位 5 HT的水平显著升高 ,分别在水杨酸钠腹腔注射 2h和 3h升高到基础值的 2 6 8%±2 7% ( x±s,以下同 )和 2 77%± 2 4 % ,通过局部脑组织灌流 ,利多卡因能显著性地降低下丘和颞皮层升高了的 5 HT的水平 ,分别降低至基础值的 85 %± 8%和 92 %± 2 6 %。结论　听觉中枢下丘和颞皮层这两个重要部位 5 HT水平的改变可能与利多卡因抑制耳鸣的机制有关。     

Toxicity of topical administration of lidocaine

It is frequently described in international literature the possibility of toxicity by local anesthesics. The lidocaine is one of them. The problems with its local use are more frequent and known but topic toxicity is also possible. We want to describe a case of toxicity by topical administration of lidocaine (Xylocain) which caused neurological disease with convulsions, and cardiological disease with ventricular fibrillation, in a patient who came for a thyroplasty. Patient's evolution was satisfactory.     

Treatment of tinnitus with intravenous lidocaine]

Intravenous lidocaine was administered in 155 cases (196 ears) with tinnitus. The injection of lidocaine, at a dose of 60 mg in men and 40 mg in women was repeated five times. The intensity of tinnitus was evaluated along a scale ranging from 0 to 10, indicating the level prior to injection. A scale ranging from 0 to 7 was estimated to be effective. After evaluation of the drug by using a double-blind test, indications for therapy were analyzed statistically according to clinical characteristics. The results obtained were as follows: 1) The effect was confirmed by using a double-blind test. 2) The effective rate was 60.2%. 3) Older cases, especially with presbyacusis, had the best indications for therapy. 4) From the clinical viewpoint of the characteristics of tinnitus, cases with hearing levels above 40dB or with dull onomatopoeic sounds were considered to have better indications for therapy. 5) None of the side effects experienced were severe, and all were transient.     

Differential lidocaine sensitivity of human voltage-gated potassium channels relevant to the auditory system.

HYPOTHESIS: Lidocaine may lead to an alteration in the processing of hearing as observed during tinnitus by inhibiting voltage-gated potassium channels at clinically relevant concentrations. BACKGROUND: Recent molecular evidence suggests that the voltage-gated potassium channels Kv 3.1 and Kv 1.1 play an important functional role in the auditory system. Lidocaine is known to influence the auditory system and may thus exert pharmacological effects on these human potassium channels. METHODS: Patch-clamp recordings were performed on the pharmacologic action of lidocaine on Kv 3.1 channels natively expressed in SH-SY5Y cells and Kv 1.1 channels expressed in HEK 293 cells. RESULTS: Lidocaine reversibly inhibited Kv 3.1 and Kv 1.1 channels in a concentration-dependent manner. The half-maximal inhibitory concentration for conductance block was 607 micromol/L for Kv 3.1 (n=47) and 4,550 micromol/L for Kv 1.1 channels (n=56), respectively. The Hill coefficients were 0.9 and 0.8. Conductance block was voltage dependent for Kv 3.1 but not for Kv 1.1 channels. The midpoint of current activation of both channels was shifted to hyperpolarized potentials. At free plasma concentrations determined during suppression (0.5-1 mg/L; 1.75-3.5 micromol/L) or induction (>1-2 mg/L; >3.5-7 micromol/L) of tinnitus Kv 3.1 and K v1.1 channels would be suppressed by at most 1.5 to 2%. CONCLUSION: Human Kv 3.1 and Kv 1.1 channels exhibited different sensitivities to the inhibitory action of lidocaine. The small effect at clinically relevant concentrations suggests that the physiologic roles of Kv 3.1 and Kv 1.1 channels in auditory neurons seem not to be impaired during the therapeutic or diagnostic application of lidocaine in the auditory system.     

Effects of topical laryngeal lidocaine on sympathetic response to rigid panendoscopy under general anesthesia.

The sympathetic response to rigid bronchoscopy, laryngoscopy and esophagoscopy, performed under general anesthesia with isoflurane, was examined in patients who either received 5 ml of 2% lidocaine (n = 7) or 5 ml of saline (n = 7), sprayed on larynx and upper trachea under direct laryngoscopy, 2 min before the introduction of the rigid bronchoscope. Blood pressure, heart rate and plasma catecholamine and lidocaine levels were measured at specific time points of the study. Topical lidocaine led to a rapid and prolonged increase in plasma lidocaine levels. Patients treated with lidocaine showed a small but significant decrease in plasma epinephrine levels from baseline following endotracheal intubation and extubation, as compared to the saline control group. Blood pressure and heart rate response during rigid panendoscopy, isoflurane requirements and time interval from termination of panendoscopy to extubation were not different between the two groups. However, in contrast to the control group, patients who had received lidocaine had no significant rise in blood pressure and heart rate from baseline following the introduction of the rigid bronchoscope. The benefit of this moderate hemodynamic stabilizing effect of lidocaine has to be weighted against the risk of decreased protective airway reflexes due to topical laryngeal lidocaine during recovery from anesthesia.     

Effects of lidocaine infusion in cats after unilateral labyrinthectomy

In the auditory/vestibular system, intravenous lidocaine hydrochloride administration has been reported to provide transient relief from severe tinnitus, reduce dizziness and emesis accompanying Meniere's disease, and sometimes improve audiometric thresholds in sensorineural hearing loss. In this study, the labyrinth was destroyed unilaterally in a series of cats. Animals constantly fell and demonstrated prominent contralateral nystagmus and a rotary motion of the head. Within four hours of a 4-mg/kg intravenous lidocaine hydrochloride injection, the cats were able to ambulate freely without falling. The nystagmus was reduced, and there was virtual absence of the rotary head motion. In contrast, the controls had persistent signs of vestibular disturbance. These results demonstrate that lidocaine infusion ameliorates the effects of unilateral labyrinthectomy in cats and thus may be a potential antivertiginous agent.