Anesthesia and analgesia
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Postoperative delirium is common in the elderly in the postoperative period. It can result in increased morbidity, delayed functional recovery, and prolonged hospital stay. In surgical patients, factors such as age, alcohol abuse, low baseline cognition, severe metabolic derangement, hypoxia, hypotension, and type of surgery appear to contribute to postoperative delirium. ⋯ Clearly, further studies are needed to determine the risk and long-term outcome of delirium in the elderly population. Research is also needed to define the effects of hypoxemia on cerebral function and whether oxygen therapy has any benefits. The geriatric-anesthesiologic intervention program of pre- and postoperative geriatric assessment, early surgery, thrombosis prophylaxis, oxygen therapy, prevention and treatment of perioperative decrease in blood pressure, and vigorous treatment of any postoperative complications showed some promise, but further definitive studies are needed.
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Anesthesia and analgesia · Jun 1995
Carbon monoxide production from degradation of desflurane, enflurane, isoflurane, halothane, and sevoflurane by soda lime and Baralyme.
Anecdotal reports suggest that soda lime and Baralyme brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO). We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane > or = enflurane > isoflurane > halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. ⋯ These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out.
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Anesthesia and analgesia · Jun 1995
Influence of isoflurane, fentanyl, thiopental, and alpha-chloralose on formation of brain edema resulting from a focal cryogenic lesion.
The objective of this study was to analyze the effects of various anesthetics on the formation of brain edema resulting from a focal cryogenic lesion. Thirty rabbits (six per group) were anesthetized with isoflurane (1 minimum alveolar anesthetic concentration [MAC] 2.1 vol%), fentanyl (bolus 5 micrograms/kg; infusion rate 1.0-0.5 micrograms.kg-1.min-1), thiopental (32.5 mg.kg-1.h-1), or alpha-chloralose (50 mg/kg). Control animals (sham operation, no lesion) received alpha-chloralose (50 mg/kg). ⋯ Brain tissue samples were collected at multiple sites close to and distant from the lesion. Mean arterial pressure, arterial PCO2 and PO2, hematocrit, body temperature, and blood glucose were not different between groups during the posttraumatic course (except for an increased arterial pressure with alpha-chloralose compared to thiopental 4-6 h after trauma). The specific gravity of cortical gray matter was significantly reduced up to a distance of 6 mm from the center of the lesion in animals anesthetized with isoflurane, thiopental, or alpha-chloralose and up to 9 mm in animals given fentanyl.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Jun 1995
Changes in plasma cholinesterase activity and mivacurium neuromuscular block in response to normothermic cardiopulmonary bypass.
The effect of reduced plasma cholinesterase (ChE) activity in response to normothermic cardiopulmonary bypass (CPB) on mivacurium neuromuscular block was studied in nine patients anesthetized with propofol/fentanyl. Mivacurium was injected intravenously as an initial bolus of 150 micrograms/kg; repeat doses of 75 micrograms/kg were given when the evoked twitch tension attained 75% of control. ⋯ Their DUR25% (time from end of injection to recovery of neuromuscular transmission to 25% of control) were 13 +/- 3 min (means +/- SD) before, 14 +/- 4 min during, and 16 +/- 4 min (P < 0.05) after CPB. It is concluded, that, although markedly reducing the patient's previously normal ChE activity, normothermic CPB had little effect on the time characteristics of mivacurium neuromuscular block.
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Spinal neostigmine produces analgesia in chronically prepared rats, but not in sheep. However, since pain itself activates bulbospinal inhibitory pathways, neostigmine may be more effective in the postoperative period. We examined in sheep the antinociceptive effect of intrathecal neostigmine in the acute postoperative period and determined the muscarinic receptor subtype activated by neostigmine. ⋯ In contrast, intrathecal neostigmine caused no antinociception in another similar study performed at least 5 days after surgery. Pirenzepine, but not AFDX-116, abolished antinociception from neostigmine, suggesting an action on M1 subtype muscarinic receptors. Intrathecal neostigmine is antinociceptive in sheep during the acute postoperative period, and these data suggest that spinal cholinergic tone, and hence intrathecal neostigmine's analgesic effect, may be enhanced during the acute postoperative period.