Anesthesia and analgesia
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Anesthesia and analgesia · Sep 2003
The effect of lidocaine on the globule size distribution of propofol emulsions.
In this study, we sought to determine the globule size distribution of a propofol/lidocaine mixture as a function of lidocaine concentration and time elapsed after mixing in a standard formulation of propofol emulsion (Diprivan) and in a new formulation containing L-lysine to improve stability. The globule size was measured with a laser diffraction technique. The median diameter of the globule size in 20 mL of Diprivan immediately after the addition of 0, 10, 20, 30, 40, and 50 mg of lidocaine was similar to that of chylomicrons, ranging from 0.28 +/- 0.01 micro m to 0.30 +/- 0.02 micro m, over the whole range of lidocaine concentration. ⋯ The maximum globule diameter in the propofol emulsion to which L-lysine was added as a stabilizer did not exceed 3.0 micro m even when the largest amount of lidocaine was added. This study demonstrated that when 30 mg of lidocaine was added to 20 mL of Diprivan and the solution was left for a period of time, the globule size increased. Its increase was minimized by the addition of L-lysine to the propofol emulsion.
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Anesthesia and analgesia · Sep 2003
Midazolam-induced muscle dysfunction and its recovery in fatigued diaphragm in dogs.
Midazolam, widely used for sedation and anesthesia, decreases contractility in nonfatigued diaphragm; however, its effects on contractility in fatigued diaphragm that are implicated as a cause of respiratory failure have not been established. We therefore studied the effects of midazolam on diaphragm muscle function and recovery in fatigued diaphragm. Dogs were divided into three groups of eight each. ⋯ At 60 min after the cessation of midazolam administration, in Group II, Pdi and Edi recovered from midazolam-induced values (P < 0.05) and returned to fatigued values. In Group III, Pdi and Edi did not change from midazolam-induced values. We conclude that midazolam causes, in a dose-related manner, diaphragm muscle dysfunction in fatigued canine diaphragm and that at a sedative dose, but not at an anesthetic dose, midazolam does not delay its recovery.
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Anesthesia and analgesia · Sep 2003
Comparative StudyThe hypnotic and analgesic effects of 2-bromomelatonin.
2-bromomelatonin is an analog of melatonin with a higher melatonin receptor affinity. We tested the hypnotic and analgesic properties of 2-bromomelatonin and compared them with those of propofol. Sprague-Dawley rats were assigned to receive 2-bromomelatonin or propofol IV, or morphine intraperitoneally. ⋯ Intraperitoneal 30 mg/kg morphine did not affect the righting reflex, but resulted in loss of response to tail clamping in all animals. 2-bromomelatonin can exert hypnotic and antinocifensive effects similar to that observed with propofol. Unlike propofol, the reduced nocifensive behavior persisted after the animals had regained their righting reflex. This study provides evidence that 2-bromomelatonin has properties that are desirable in anesthetics or anesthetic adjuvants.
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Anesthesia and analgesia · Sep 2003
Case ReportsEpidural blood patch placed in the presence of an unknown cervical epidural hematoma.
We discuss a case detailing a favorable outcome of an epidural blood patch performed in the presence of an unknown cervical epidural hematoma. The case highlights the use of a spinal needle for epidural space confirmation, the importance of waiting for final consultation and radiologic testing results before therapeutic intervention when possible, and the use of an epidural blood patch, even in the setting of a known epidural hematoma.
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Anesthesia and analgesia · Sep 2003
Comparative StudyAntinociceptive properties of neurosteroids: a comparison of alphadolone and alphaxalone in potentiation of opioid antinociception.
In this study, we investigated the antinociceptive and sedative effects of the opioids fentanyl, morphine, and oxycodone given alone and in combination with two neurosteroids: alphadolone and alphaxalone. An open-field activity monitor and rotarod apparatus were used to define the sedative effects caused by opioid and neurosteroid compounds given alone intraperitoneally to male Wistar rats. Dose-response curves for antinociception were constructed using only nonsedative doses of these drugs. ⋯ Alphaxalone given alone had no antinociceptive effects at nonsedative doses and it had no effect on opioid antinociception. Neither neurosteroid caused sedative effects when combined with opioids. We conclude that coadministration of alphadolone, but not alphaxalone, with morphine, fentanyl, or oxycodone potentiates antinociception and that this effect is not caused by an increase in sedation.