ABSTRACT
The relation of plasma concentration of d-tubocurarine (dTc) to neuromuscular blockade, and the distribution and urinary excretion of dTc was determined in neonates (n = 4), infants (n = 6), children (n = 8), and adults (n = 8). The plasma concentration-time course curves to 24 hr are best described for all groups by three-compartment models. Both neonates and infants exhibit decreased plasma clearance (CLP), 1.1 +/- 0.08 and 1.0 +/- 0.06 ml X kg-1 X min-1, and in addition a prolonged t1/2 terminal phase, 311 +/- 44 and 306 +/- 35 (mean +/- SEM, min). The neonates' 24-hr urinary excretion, 27 +/- 2 (mean +/- SEM, % total dose) is significantly less than the adult value, 45 +/- 4% total dose. There was no significant difference seen in the log plasma concentration-evoked compound electromyogram (ECEMG) response between 20-80% paralysis for adults, children, infants, and five of the seven neonates studied. Two of the neonates had a significant shift of their log concentration-response curve to the right. There was also no significant difference between any of the groups in the time for 50% return of ECEMG stimulus height or the time required for recovery of the ECEMG from 25 to 75% of control value. for recovery of the ECEMG from 25 to 75% of control value.
Subject(s)
Aging , Tubocurarine/metabolism , Adult , Child, Preschool , Electromyography , Humans , Infant , Infant, Newborn , Injections, Intravenous , Kinetics , Neuromuscular Junction/drug effects , Tubocurarine/pharmacologyABSTRACT
Exhaled volumes were measured in 8 children during uptake and elimination of 3 percent and 75 percent N2O, using a volume-controlled ventilator. Absorption of 75 percent N2O during induction reduced the exhaled minute volume, which fell a mean of 16 percent in the 1st or 2nd minute and returned to normal by 15 to 20 minutes. Elimination was the mirror image of uptake; the mean increase in the exhaled minute volume was 13 percent. The concentration effect during uptake was measured (3 percent versus 75 percent N2O) and the data were used to calculate a fall in alveolar volume of at least 8 percent by the 2nd minute of uptake. The type of ventilation (volume-limited, pressure-limited, or spontaneous) was seen to have a modifying role on the respiratory pattern caused by the absorbed and excreted volume of N2O.
Subject(s)
Anesthesia, Inhalation , Lung/metabolism , Nitrous Oxide/metabolism , Child , Child, Preschool , Clinical Trials as Topic , Dose-Response Relationship, Drug , Humans , Infant , Lung Volume Measurements , Respiration/drug effectsABSTRACT
An in-vitro experiment demonstrated the concentration effect of N2O (3% versus 75%) during elimination and during uptake. Other pulmonary absorption-excretion phenomena also occur simultaneously, as paired events during uptake and then during elimination:diffusion hyperoxia and diffusion anoxia; alveolar concentration of CO2, and alveolar dilution of CO2. These clinical phenomena, as well as the second gas effect, are all related, and the pulmonary absorption-excretion volume is found to depend in part on the type of ventilation:volume controlled, pressure controlled, or spontaneous respiration.
