[Transdermal Local Anesthetics].

Taking EMLA cream and Penles tape 18 mg as examples, this article describes the conditions for skin penetration of topical anesthetics, with their onset time of action, duration of effect and a precautions for their use. EMLA cream is a unique cream for topical anesthesia which is the eutectic mixture of lidocaine and propitocaine to increase skin penetration. The safety study demonstrated that blood concentrations of active ingredients of EMLA cream were below toxic levels. EMLA cream, with confirmed high skin penetrability and safety, should be used for pain reduction of various treatments for many diseases. Here in Japan, EMLA cream has indications not only for pain reduction of skin laser therapy but also for reduction of needle puncture pain. This means the use of topical anesthesia would be expanded to wider ranges of treatments.

[General anesthesia for two patients taking methylphenidate (Ritalin)].

We experienced anesthesia care for two patients taking methylphenidate (Ritalin), which is a central nervous system stimulant of amphetamine analogues, usually administered for narcolepsy or refractory depression. The proper dose of methylphenidate is 20-60 mg per day. General anesthesia with epidural anesthesia was administered to both cases for total hip replacement. One patient could discontinue taking methylphenidate five days before the operation, but the other patient could not. Both cases needed more anesthetics than usual on induction, but very stable condition could be maintained during and after the operations. We consider that it is possible to perform general anesthesia safely for patients taking a usual dose of methylphenidate.

[Selection of drugs suitable for the treatment of intractable chronic pain patients by using drug challenge tests].

Intractable chronic pain is very difficult to treat. Nowadays, small amounts of drugs, that have different actions on the mechanism of pain relief are administered intravenously, and the effects of the test drugs on individual chronic pain patients are investigated by using the evaluation method of the visual analogue scale (VAS). This will enable elucidation of the mechanisms of pain in each chronic pain patient. Based on this information, drugs that are effective for the treatment of individual chronic pain patients can be prescribed. Drugs that are used for the drug challenge tests are phentolamine, barbiturate, morphine, lidocaine, ketamine, benzodiazepine, adenosine-3-phosphate (ATP), neurotropine, and prostaglandine E1. Phentolamine is effective for the management of sympathetically maintained pain. Barbiturate and morphine are effective for the treatment of deafferentation pain and nociceptive pain, respectively. Lidocaine is effective for the treatment of neuropathic pain; ketamine, for allodynia; and benzodiazepine, for anxiety-related pain. ATP exerts a positive effect in total pain management. Neurotropine and prostaglandine E1 are effective for the management of neuropathic pain and ischemic pain, respectively. These tests aid in the selection of drugs that maybe useful for the treatment of intractable chronic pain in patients.

[Equipment for electro-convulsive therapy].

ECT (electro-convulsive therapy) has been used for the treatment of depressive patients. First it was applied in patients only with sedatives without muscle relaxants, but now we employ muscle relaxants to avoid convulsion and its complications. It is called modified ECT (mECT). General anesthesia using muscle relaxant for ECT is now increasingly employed in Japan. Furthermore, there are some reports that ECT is effective not only in depressive patients but in chronic pain patients. This is why anesthesiologists are especially interested in ECT. In this chapter, clinical application, equipment and complications of ECT are discussed.

[Patient safety management in surgery].

This article deals with practical guidelines for informed consent to surgery and strategies to avoid adverse events during the operative and postoperative periods. It also describes what to do in the event of accidents and what should or should not be done to avoid medical litigation.

Suppressive effect of spinal dorsal-horn neuronal activity by local spinal-cord cooling is reversed by naloxone in cats.

PURPOSE: The purpose of this study was to assess the effect of local spinal cord cooling on spinal dorsal-horn neuronal activity, with special emphasis on the role of endogenous opioid. METHODS: Decerebrate, spinal-cord-transected cats ( n= 30) were subjected to local spinal-cord irrigation, using 0.9 N saline solution (15 degrees C; n= 15, and 35 degrees C; n= 15) for 90 min. The extracellular, single-cell activity of spinal dorsal-horn neurons responding to noxious stimulation was recorded. Sixty-one minutes after induction of local spinal-cord irrigation, naloxone (0.1 mg.kg(-1)) was administered intravenously. Local spinal-cord blood flow was measured using the hydrogen clearance technique. RESULTS: Local spinal cord cooling produced significant suppression of both spontaneous and evoked activity (33.1 +/- 7.7% and 31.4 +/- 5.5%, respectively; mean +/- SE). Naloxone reversed this suppression immediately. Local spinal-cord blood flow was significantly reduced during spinal-cord cooling, but naloxone did not change local spinal-cord blood flow. CONCLUSION: The results demonstrate that endogenous opioids may play an important role in dorsal-horn neuronal suppression induced by local spinal-cord cooling.