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Abstract Mivacurium chloride (Mlvaaon) is a new short-acting non-depolarizlng neuromuSCular blocking agent. recently introduced in anaesthesia practice. It is thought to be metabolized in plasma by P88Udocholinesterase. at about 88% of the rate c:A metabolism c:A suxamethonium. It is POSSiblethat a small amount may also be excreted Unchanged in urine. Patients with ~stage renal failure may have reduced plasma cholinesterase activity. The cause c:A this is uncertain, but it is thought not to be caused by the techniques c:A hemo- or peritoneal dialysis. In this work, it was decided to perform a ~ic study c:A mivacurlum in patients with end-stage renal ’ailure COfnP8l’8dwith heIlthy control. As thla ctug has a short elimination hal-lite c:A about 17 min., we used a bolus doee followed by a COIlStMt im..ion at the drug. It was found that alter the bolus doee 01 mlvaaon, !118M (SO) d.prellion c:A T1 was greater in the anephric ~ than in normal ~ (100 (0.001) VI. 99 (0.014) % P < 0.015) and recovery c:A T1/To to 5% was sIcm. (23.5 (5.2) VI. 14.8 (2.7) min. p < 0.001). Aneptvic patients required a slower infUSion rate (3.2 (1.8) VI. 8.8 (1.3) lIQI1cghnin. P < 0.001]. 8ponranecg reeoli’8ly of T1/To (from 25% 1075%) ••• infu!IIon -11IIo llatll. in anephric P8tlInIs (13 (2.9) VI. 8.2 (1.7) ”*’- p< 0.001). TIme fron•• ” •••Jillg infUIlon to 70% recc •• Y c:A TOF ratio was aIIo prolonged in 8nIpR1c patiaillt (20.2 (1.7) VI. 13.8 (1.5) min. P < 0.001]. Plasma cholinesterase aetMty was ••• in the anephi1c.group (3338.2 (1528.9) VI. 5254.1 (1192.5] iuJIitre p < 0.001) and there was a negative correlation overall between cholinesterase activity and time 105% recovery c:AT1/To alter the bolus doee (P < 0.001). We conctude that Pltilnllt with chronic renal failure may require • redUced doee of mlv8cu1t.m. The intubating COIldtioilS at 2 min. alter mlvacurUn 0.25 mg,1cgShD/Jed that: in Group I, the COI’1ditlonswere exe.lent in 10 pati.”llS (50%), good in 8 palleullt (<40%) and poor in 2 patients (10%). In Group II. the conc:IItionswere excellent in 12 patienllS (60%). good in 5 patients (25%), poor in 2 patients and impossible in one patient (5%), this case was anatOmically difficult and the trachea Was intubated at 5 min. We conclude that in elective procedure, when tI:lere is no need to rapid s~ jntuba~. mivacurium provides a useful non-depoIarizing alternative to succinylcholine. The haemodynamic effects of mivacurium was also assesSed, the results demonstrated that when mivacurium 0.25 mgJkg was slowly injected (over 30 seconds) the main effect was a transient decrease in arterial blood PI’888Ur8. MAP DROP was transient and less than 10% from base line. No significant differencee were fOUndbetween &nephric and healthy conbot patients. In an a\l8r8ge healthy patient, the ~ effects 01 miv8curUn at high dosage. adequate for relatively rapid tracheal intubation. WOUldseem to present ,a minor Clinical pro/)/em 01 short-liwd ”’.H’il8la’i’~.~ • .1 In relatively Sick individuals, such as patients with COl’Of18Iy artery or valvular heart disease. who are ree.l~,4iWeticsor be. NICk••.•,.,. haemOdynamlc effects of mlvacurium may be augmented, clue to rec:tucedIntravucul8i volume or the blockade 01 the comp-ensatory mecha”In. ~ ,;;:i:njectIOn of mivaeurium or administration by infusion, would seem advisable. since the haemOdynamIc effects are redllC8d by injecIlon OYer 30-60 second8 |