Anesthesiology
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End-expiratory pressure is often used to improve arterial oxygenation and prevent atelectasis in intubated spontaneously breathing patients. To compare the effect of extubation from low levels of expiratory positive airway pressure (EPAP) of extubation from ambient airway pressure, functional residual capacity (FRC) and arterial blood oxygen tension (Pao2) were measured in 12 spontaneously breathing patients during three conditions in the peri-extubation period: 1) intubated at 5 cm H2O EPAP (EPAP 5); 2) intubated at ambient airway pressure (EPAP 0); and 3) within one hour after extubation. ⋯ The magnitude of increase in FRC and Pao2 on extubation from EPAP 0 varied inversely with the patient's lung thorax compliance (r = -0.84, P less than 0.005). It was concluded that a period of EPAP 0 is not necessary in the weaning period, and that it may be deleterious in patients with compromised lung thorax mechanics.
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The effects of intrathecally administered opiates (morphine sulfate and meperidine), alpha-adrenergic agonists (clonidine and ST-91) and baclofen were examined on the shock titration threshold of macaque monkeys chronically prepared with intrathecal (I) or epidural (E) catheters. Spinal opiates produced a long-lasting analgesia which was antagonized by naloxone. The order of potency was I morphine greater than I meperidine greater than E meperidine greater than E morphine. ⋯ Baclofen, in contrast, produced a dose-dependent decrease in muscle strength. That the intrathecal drugs did not produce anesthesia was demonstrated by their failure to block the avoidance response to ensuing ear shock cued by a light tactile stimulus applied to the hind paw. These results clearly indicate that a powerful analgesia can be produced by selectively activating adrenergic, opiate, and baclofenergic receptor systems in the spinal cord.
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The pharmacokinetics and effectiveness of edrophonium antagonism of d-tubocurarine neuromuscular blockade were compared with that of neostigmine in surgical patients anesthetized with halothane and nitrous oxide. After an intravenous (iv) injection of d-tubocurarine (0.3 mg/kg), the single twitch tension was allowed to return to five per cent of the control level. Edrophonium, 0.5 or 1.0 mg/kg (n = 12), or neostigmine, 0.07 mg/kg (n = 6), was then given iv in combination with atropine, 1.0 mg, as a 2-min controlled infusion. ⋯ Except for a longer distribution half-life, the pharmacokinetic variables for edrophonium did not differ significantly from those for neostigmine. The elimination half-lives of edrophonium and neostigmine were 110 +/- 34 min (mean +/- SD) and 77 +/- 47 min, respectively. The authors therefore conclude that edrophonium, 0.5-1.0 mg/kg, has pharmacokinetic variables comparable to neostigmine and produces prompt, sustained, and effective antagonism of d-tubocurarine neuromuscular blockade.