Dose‐response curves of succinylcholine (SuCh) were obtained in anesthetized patients by means of mechanograms of the flexion‐grip response of the hand to ulnar nerve stimulation. A subparalyzing dose (0.04 mg/kg b.w.) of d‐tubocurarine (d‐TC) administered prior to SuCh (0.025–1.6 mg/kg b.w.) exhibited a shift of the dose‐response curves toward the right, i.e., a diminishing effect on magnitude and duration of the SuCh induced neuromuscular blockade. The effective dose of SuCh required to produce a half‐maximal inhibition of the contractile force (ED50, 0.12 mg/kg before d‐TC) was increased to 0.3 mg/kg (15 min after d‐TC), 0.26 mg/kg (after 30 min), and 0.23 mg/kg (after 45 min). Thus, d‐TC pretreatment employed under clinical conditions to prevent potential hazards of SuCh requires a significant larger dose of SuCh to ensure consistently adequate relaxation.ZUSAMMENFASSUNGDosis‐Wirkungsbeziehungen von Succinylcholin (SuCh) (0,025–1,6 mg/kg Körpergewicht) wurden mit Hilfe von Mechanogrammen der Beuge‐ und Faust‐schlußbewegung der Hand nach elektrischer Ulnarisreizung an narkotisierten Patienten ermittelt. Die Vorausinjektion von d‐Tubocurarin (d‐TC) in der unterschwelligen Dosierung von 0,04 mg/kg Körpergewicht fuhrte zu einer Rechtsverschiebung der Dosis‐Wirkungskurven von SuCh, d.h. d‐TG vermindert Ausmaß und Dauer der neuromuskulären Hemmwirkung von SuCh. Die Effektivdosis von SuCh, die eine halbmaximale Hemmung der Kontraktionskraft bewirkt (ED50; 0,12 mg/kg ohne d‐TC) steigt auf 0,3 mg/kg 15 min nach d‐TC an bzw. 0,26 mg/kg (nach 30 min) und 0,23 mg/kg (nach 45 min). Wird unter klinischen Bedingungen vor einer SuCh Injektion ein Muskelrelaxans vom kompetitiven Typ, z.B. d‐TC verabfolgt, um potentielle Nebenwirkungen von SuCh zu verhuten, ist eine hohere Dosis SuCh erforderlich, um immer eine gute Muskelerschlaffung zu gewährleisten.
THE A~aaa~ of children to survive long surgical procedures depends largely on two factors-pulmonary ventilation and fluid balance. The essential features of adequate ventilation are generally recognized, but the principle of fluid therapy in children undergoing surgery is difllcult to put into practical terms and is poorly understood, x The purpose of this study is an attempt to further the understanding of the problem of fluid therapy in children and to suggest some practical answers to the problems. FUNDAMENTALS OF FLU-d) BALANCE 1. Total Body Water Approximately 80 per cent of the total body weight of the newborn infant consists of fluid. This drops to 75 per cent in the young child and to 55 to 60 per cent in the adult? 2. Blood Volume The blood volume in infants is approximately 80 ml./kg. In adult males it is 65 to 70 ml./kg, and in females 55 to 85 ml./kg., varying inversely with the amount of body fat present. 8 3. Body Fluid Compartments The distribution of fluids within the body compartments in the infant differs markedly from that in the adult. In the infant the cellular compartment comprises 35 per cent of the body weight while the extra-cellular comprises about 40 per cent. In the adult, while the cellular compartment comprises 40 per cent of the body weight, the extra-cellular comprises only 13 per cent. 4. Renal Function Although it is presumably in salt and water balance at birth, generally the newborn baby is precipitated toward dehydration by the lapse of some 24 to 48 hours before it begins ingestion of fluid. According to McCance ~ the first three or four postnatal days are attended by loss in body weight of 6 to 10 per cent, probably attributable to dehydration. From birth until the third day, the plasma concentratidns of urea, uric acid, and NPN generally increase. According to Thomson, 5 full-term infants excrete some 9.0 c.c. of water per day in the first two days, this figure rising to 225 c.c. by the twelfth day. The specific
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