Local anesthesia. 2

Age and Sex Variation in the Duration of Action and Corneal Touch Threshold (CTT) following Instillation of 0.5% Topical Ophthalmic Proparacaine and Tetracaine Hydrochlorides

PURPOSE

We investigated the effect of age and sex on corneal touch threshold (CTT) and duration of action following administration of 0.5% topical ophthalmic proparacaine and tetracaine hydrochlorides.

METHODS

A prospective, randomized, subject-masked, crossover study design was used. Two hundred and forty human volunteers were enrolled in the study. Corneal touch threshold (CTT) was determined using a Cochet-Bonnet esthesiometer. CTT was measured every 15 seconds for the first 1-minute and at 5-minute intervals subsequently for a period of 40 minutes after the application of each anesthetic. CTT and duration of action of the ophthalmic solutions were tested for statistical significance using repeated measures ANOVA.

RESULTS

The total duration of effect was 20 minutes for females and 25 minutes for males for both anesthetics. The total duration of the effect of both solutions decreased with increasing age; however, elderly participants had the longest duration (5 minutes) of the maximal effect (minimum CTT) of the two ophthalmic preparations. There was a significant influence of sex, F (2.39, 569.65) = 2.86, p=0.04; F (3.48, 828.19) = 4.41, p=0.003, and age, F (4.78, 566.18) = 8.97, p < 0.001; F (7.19, 852.56) = 20.55, p < 0.001 on CTT following application of proparacaine hydrochloride and tetracaine hydrochloride, respectively.

CONCLUSION

CTT and duration of anesthetic effect after instillation of 1 drop of 0.5% proparacaine hydrochloride and 0.5% tetracaine hydrochloride vary based on sex and age.

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.

A Pilot Study on the Effect of Epinephrine on Botulinum Toxin Treatment for Periorbital Rhytides

BACKGROUND

Relaxation of hyperactive facial muscles by injection of botulinum toxin type A (BOTOX, Allergan Inc., Irvine, CA) represents the most common cosmetic procedure performed in the United States.

OBJECTIVE

The objective of this split-face randomized double-blind study was to determine the effect of epinephrine (EPI) on the efficacy of BOTOX treatment of muscle hyperactivity in the upper face.

MATERIALS AND METHODS

Fourteen subjects (ages 39-57 years) with moderate to severe periorbital rhytides were enrolled. Study patients were blinded to the two treatment arms, BOTOX and BOTOX plus EPI 1:100,000. Subjective and objective evaluations were performed at 0 and 4 days and 1, 3, and 6 months, and clinical improvement was assessed using a nominal scale from 0 to 4, corresponding to 0, 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100% improvement, respectively. The incidence of adverse events was also recorded. RESULTS Fourteen subjects with moderate to severe periorbital rhytides were treated with BOTOX or BOTOX plus EPI. One subject was discontinued from the study after receiving asymmetric doses of BOTOX. At 4, 30, and 90 days after treatment, subjective and objective improvement scores revealed that EPI enhanced the efficacy of BOTOX when compared to BOTOX alone. By 3 months, the effect of BOTOX and BOTOX plus EPI had peaked and continued to fall through 6 months. One of 14 patients did not appear to respond to BOTOX treatment. Both treatments were well tolerated with no serious adverse events.

CONCLUSION

To our knowledge, we are the first to test under randomized double-blind conditions the effect of EPI on efficacy of BOTOX. Our data suggest that addition of EPI may accelerate the rate of onset as well as the short-term efficacy of BOTOX for treatment of periorbital rhytides.

Use of tetracaine, epinephrine, and cocaine as a topical anesthetic in the emergency department

The combination of tetracaine, epinephrine, and cocaine has gained wide acceptance as a topical anesthetic agent for use on pediatric dermal lacerations in the ED. This is despite the fact that the optimal dose and formulation have yet to be determined. TAC can be applied painlessly to wounds and is about as effective as lidocaine infiltration for anesthetizing pediatric facial and scalp lacerations. It is relatively ineffective on lacerations located elsewhere or in adults. The most commonly used TAC solution contains high concentrations of cocaine, tetracaine, and epinephrine, drugs that individually can cause serious toxicity if absorbed in sufficient amounts. In addition, the three components of TAC may interact to potentiate their intrinsic toxicities. The deliberate and inadvertent application of TAC to mucous membranes has caused status epilepticus and two pediatric deaths. The risk of toxicity from misapplication of TAC is heightened because TAC is most effective and therefore most widely used on pediatric facial and scalp lacerations. Cocaine is also absorbed after TAC is applied to dermal lacerations and may cause toxicity by this route. Until additional research is performed to establish the minimum effective dose of TAC and its potential toxicity and until FDA approval is granted, we do not think that it can be recommended as the drug of choice for pediatric facial and scalp lacerations in the ED. If TAC is administered, a maximum dose of 2 to 3 mL of the "half-strength" formula proposed by Bonadio and Wagner should be used, and application should be performed by medical personnel, using a soaked gauze or cotton ball. Care should be taken to make sure none of the solution comes in contact with mucous membranes, and TAC should not be applied to lacerations involving the vermillion border of the lip or the lip itself. Close medical monitoring of the patient is essential to detect signs of toxicity. Research on other topical agents such as tetracaine with epinephrine is also needed. Although anesthetizing wounds painlessly remains a worthy goal, exposing patients to added and unknown risks and increasing the cost of health care is unacceptable.

Prolongation of anesthesia in Mohs micrographic surgery with 2% lidocaine jelly

The authors performed a prospective, randomized trial of topical 2% lidocaine jelly in patients with basal cell or squamous cell carcinomas to test the effectiveness of the jelly in prolonging the time of anesthesia between the multiple stages of Mohs micrographic surgery. There was a 48% increase in the duration of anesthesia achieved by the use of 2% lidocaine jelly in patients given 1% lidocaine with epinephrine. In patients given 1% lidocaine without epinephrine, there was approximately a 2.5 times greater duration of anesthesia achieved by using topical 2% lidocaine jelly.

Local anesthesia in dermatologic surgery

With the growth of dermatologic surgery the appropriate use of local anesthesia is becoming an important issue. Thoughtful use of local anesthesia can improve the patient's experience and facilitate the surgical procedure. In this review we discuss historical and pharmacologic aspects of local anesthetic agents. Emphasis is placed on clinical considerations, including contraindications, toxic reactions, and detailed descriptions of anesthetic use.

Anesthesia for dermatologic surgery

The increased scope and complexity of dermatologic surgery has led to a need for greater skill in the preoperative administration of local and regional anesthesia. This article reviews the mechanism of action of local anesthetic agents, their pharmacologic properties and adverse reactions, and describes accepted techniques for safely and effectively establishing local and regional anesthesia for skin surgery. The presentation is limited to those techniques of greatest use to the office practitioner.

Regional cyclic AMP systems during secondary ischemia in gerbils: influence of anesthetic agents

The effect of three modes of anesthesia was evaluated with regard to regional damage to central cyclic nucleotide systems in the gerbil brain as a consequence of bilateral ischemia (clamping the common carotids) followed by various periods of recirculation. The injection of thiopental as much as 90 min before stroke prevented damage to chemical activation [catecholamines, guanosine triphosphate (GTP), or forskolin] of adenylate cyclase. However, the basal enzyme activity was lower in all brain regions whether thiopental was administered to stroke or sham-operated animals. Injection of ketamine drastically shortened the survival times of gerbils undergoing stroke followed by recirculation. About 90% of the animals could tolerate a maximum of only 15 min stroke with 15 min recirculation. At this time frame the patterns of activation of adenylate cyclase in only the olfactory tubercle and hippocampus were altered. When procaine was used as a local anesthetic agent during surgery, damage to catecholamine-, GTP-, or forskolin-activated adenylate cyclase was evident to varying degrees in the frontal cortex, hippocampus or olfactory tubercle, but not in the nucleus accumbens and olfactory bulb of gerbils subjected to 60-min stroke followed by 15 or 150 min of recirculation. The degree of enzyme damage was neither correlated with the fed vs. fasted state of the animal nor with the whole blood concentration of glucose. A depression in the amplitude of visually evoked potentials correlated to neurological signs and to enzyme damage. During anesthesia, ketamine increased steady-state concentrations of cyclic AMP in the frontal cortex and hippocampus from gerbil brains that had been rapidly inactivated by microwave irradiation. Thiopental increased steady-state cyclic AMP in only the olfactory tubercle. Cyclic GMP concentrations were unchanged by any anesthetic agent. In animals completely recovering from anesthesia and occluded for a brief period followed by 10 min of reflow, steady-state concentrations of only cyclic AMP were augmented.

Prevention of obturator nerve stimulation during transurethral surgery

The obturator nerve passes in close proximity to the inferolateral bladder wall, bladder neck and lateral prostatic urethra. During a transurethral operation resection in these areas may result in stimulation of the obturator nerve, causing violent adductor contraction and possible inadvertent bladder perforation. To block this reaction d-tubocurarine and succinylcholine can be used during general anesthesia. However, it often is preferable to use spinal anesthesia during transurethral operations. Local anesthetic blockade of the obturator nerve as it passes through the obturator canal if effective for adductor spasm during spinal anesthesia. We herein describe the anatomy, pharmacology, technique and results of local obturator nerve blockade.

Inhibition of adsorption of West-Nile and herpes simplex viruses by procaine

The effect of the local anaesthetic drug procaine on the adsorption of two enveloped viruses was studied. Physiological concentrations of the drug (7 X 10(-3)--7 X 10(-2) M) strongly inhibited the adsorption of both West-Nile and herpes viruses as determined by plaque assay and the infective center assay.

Degenerative changes in masseter muscle following injection of lidocaine: a histochemical study

Changes in succinic dehydrogenase, adenosine triphosphatase, and phosphorylase activities occurred in masseter muscle by 15 minutes following injection of 2% lidocaine. Abolishment of phosphorylase activity suggested an effect on the sarcoplasmic reticulum. Increased staining for succinic dehydrogenase and adenosine triphosphatase activities suggested damage to mitochondria and myofibrils, respectively. Leucine aminopeptidase and glucose-6-phosphate dehydrogenase activities appeared in macrophages.

Human hepatic blood flow and its relation to systemic circulation during intravenous infusion of lidocaine

Twelve healthy young volunteers were studied before and during intravenous administration of lidocaine at a dose rate of 2 or 4 mg/min. Five additional volunteers, who did not receive lidocaine solution but were given the same amount of physiological saline, were studied in the same manner. Heart rate, cardiac output, mean arterial blood pressure, mean right atrial blood pressure, estimated hepatic blood flow and plasma concentration of lidocaine were measured repeatedly. The results showed an increase in heart rate, cardiac output and mean arterial blood pressure, the latter two variables in relation to the plasma concentration of lidocaine. The estimated hepatic blood flow increased, partly as a result of the reduction of splanchnic vascular resistance and partly due to the stimulation of cardiac output. The decrease in splanchnic vascular resistance was proportional to the plasma concentration of lidocaine.

Nerve blocks of the foot

Emergency treatment of foot injuries can be made less painful by regional block anesthesia. There is limited medical literature on these techniques and many physicians, while familiar with regional anesthesia of the upper extremity, are not experienced with nerve blocks in the lower extremity. Infiltration anesthesia of the plantar structures of the foot and toes can be very painful and may inhibit healing. Regional anesthesia avoids both of these problems and can prove effective and useful. This paper discusses the techniques and possible complications of nerve block anesthesia of the foot.