Articles: anesthetics.
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Anesthesia and analgesia · Dec 1987
Comparative Study Clinical Trial Controlled Clinical TrialClinical pharmacokinetics of carbonated local anesthetics. II: Interscalene brachial block model.
A double-blind comparison of 1.1% lidocaine carbonate and 1.0% lidocaine hydrochloride was carried out in 30 healthy adult patients undergoing upper-extremity surgery under interscalene brachial plexus block. Epinephrine (1:200,000) was added to both solutions just before injection. As compared to lidocaine hydrochloride, lidocaine carbonate produced, in addition to a 38% reduction in onset time, a remarkable increase in the extent of anesthesia: lidocaine carbonate produced surgical anesthesia of the entire upper extremity including the hand in 87% of the patients, whereas lidocaine hydrochloride produced similar anesthesia in only 53% of the patients. Thus, supplemental blocks were required in 66% of the patients who received lidocaine hydrochloride, whereas they were required in only 25% of those who received lidocaine carbonate.
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Anesthesia and analgesia · Dec 1987
Central nervous system complications after 6000 retrobulbar blocks.
Six thousand consecutive patients in whom retrobulbar anesthesia was performed by an anesthesiologist before ophthalmic surgery were studied. Sixteen patients (1 in 375) developed signs and symptoms presumed to be caused by the direct spread of the local anesthetic agents to the central nervous system. These signs and symptoms ranged from drowsiness, blindness of the contralateral eye, abnormal shivering, or vomiting, through to respiratory depression, apnea, hemiplegia, aphasia, convulsions, unconsciousness, and cardiopulmonary arrest. ⋯ The time of the onset of symptoms after the retrobulbar injection was variable (average 8 min, range 2 to 40 min). The possibility of a life-threatening complication occurring was rare (1 in 750) but unpredictable. The need for closely monitored anesthesia care of all patients having surgery under retrobulbar anesthesia is stressed.
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1 The antinociceptive effects of systemically-administered procaine, lignocaine and bupivacaine were examined in mice and rats by using the hot-plate, writhing and tail flick tests. 2 In both species all three local anaesthetics produced significant antinociception which was prevented by atropine (5 mg kg-1, i.p.) and by hemicholinium-3 (1 microgram per mouse, i.c.v.), but not by naloxone (3 mg kg-1, i.p.), alpha-methyl-p-tyrosine (100 mg kg-1, s.c.), reserpine (2 mg kg-1, i.p.) or atropine methylbromide (5.5 mg kg-1, i.p.). 3 Atropine (5 mg kg-1, i.p.) which totally antagonized oxotremorine (40 micrograms kg-1, s.c.) antinociception did not modify morphine (5 mg kg-1, s.c.) or baclofen (4 mg kg-1, s.c.) antinociception. On the other hand, hemicholinium, which antagonized local anaesthetic antinociception, did not prevent oxotremorine, morphine or baclofen antinociception. 4 Intracerebroventricular injection in mice of procaine (200 micrograms), lignocaine (150 microgram) and bupivacaine (25 micrograms), doses which were largely ineffective by parenteral routes, induced an antinociception whose intensity equalled that obtainable subcutaneously. Moreover, the i.c.v. injection of antinociceptive doses did not impair performance on the rota-rod test. 5 Concentrations below 10(-10) M of procaine, lignocaine and bupivacaine did not evoke any response on the isolated longitudinal muscle strip of guinea-pig ileum, or modify acetylcholine (ACh)-induced contractions. On the other hand, they always increased electrically-evoked twitches. 6 The same concentrations of local anaesthetics which induced antinociception did not inhibit acetylcholinesterase (AChE) in vitro. 7 On the basis of the above findings and the existing literature, a facilitation of cholinergic transmission by the local anaesthetics is postulated; this could be due to blockade of presynaptic muscarinic receptors.
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Randomized Controlled Trial Clinical Trial
EMLA cream reduces the pain of venepuncture in children.
EMLA cream (eutectic mixture of local anaesthetics) was tested in a double-blind clinical trial to examine its effect on the pain of venepuncture at induction of anaesthesia in 40 children (aged 3-13 yrs). Four pain-assessment methods were used and an assessment of the technical ease of venepuncture was made. EMLA was found to reduce significantly the pain and technical difficulty of venepuncture. This study confirms that EMLA is an effective method of reducing the pain and technical difficulty of paediatric venepuncture using 25-gauge needles for induction of anaesthesia in children.