Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2001
Randomized Controlled Trial Clinical TrialThe effects of different mouth-to-mouth ventilation tidal volumes on gas exchange during simulated rescue breathing.
The American Heart Association recommends tidal volumes of 700 to 1000 mL during mouth-to-mouth ventilation, but smaller tidal volumes of 500 mL may be of advantage to decrease the likelihood of stomach inflation. Because mouth-to-mouth ventilation gas contains only 17% oxygen, but 4% carbon dioxide, it is unknown whether 500-mL tidal volumes given during rescue breathing may result in insufficient oxygenation and inadequate carbon dioxide elimination. In a university hospital research laboratory, 20 fully conscious volunteer health care professionals were randomly assigned to breathe tidal volumes of 500 or 1000 mL of mouth-to-mouth ventilation gas (17% oxygen, 4% carbon dioxide, 79% nitrogen), or room air control (21% oxygen, 79% nitrogen) for 5 min. Arterial blood gases were taken immediately before, and after breathing 5 min of the experimental gas composition. When comparing 500 versus 1000 mL of mouth-to-mouth ventilation tidal volumes with 500 mL of room air, 500 mL of mouth-to-mouth ventilation tidal volume resulted in significantly (P < 0.05) lower mean +/- SEM arterial oxygen partial pressure (70 +/- 1 versus 85 +/- 2 versus 92 +/- 3 mm Hg, respectively), and lower oxygen saturation (94 +/- 0.4 versus 97 +/- 0.2 versus 98 +/- 0.2%), but increased arterial carbon dioxide partial pressure (46 +/- 1 versus 40 +/- 1 versus 39 +/- 1 mm Hg, respectively). Sixteen of 20 volunteers had to be excluded from the experiment with 500 mL of mouth-to-mouth ventilation gas after about 3 min instead of after 5 minutes as planned because of severe nervousness, sweating, and air hunger. We conclude that during simulated mouth-to-mouth ventilation, only large (approximately 1000 mL), but not small (approximately 500 mL) tidal volumes were able to maintain both sufficient oxygenation and adequate carbon dioxide elimination. ⋯ To provide efficient mouth-to-mouth ventilation, it is important to administer tidal volumes of 1000 mL; tidal volumes of 500 mL were not adequate.
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Anesthesia and analgesia · Nov 2001
Local anesthetic actions on thromboxane-induced platelet aggregation.
Some local anesthetics (LA), in concentrations present in blood during IV or epidural infusion, inhibit thrombus formation in the postoperative period. Studies on thromboxane A2 (TXA2) signaling in a recombinant model suggest that interference with TXA2-induced platelet aggregation may explain, in part, the antithrombotic actions of epidural analgesia and IV LA infusion. In this study we investigated the effects of clinically used LAs (lidocaine, ropivacaine, and bupivacaine) on TXA2-induced early platelet aggregation (1-5 s) by using quenched-flow and optical aggregometry. Our findings demonstrate that the LAs tested seem to have only a limited ability to inhibit TXA2-induced platelet aggregation assessed at early times (1-5 s). Therefore, the clinical effects of LAs on thrombi formation are unlikely to be explained by this manner alone. At large LA concentrations, moderate effects were obtained. Prolonged incubation with LA did not significantly increase effectiveness, and the lack of an effect could not be explained by generation of secondary mediators. The results were independent of the anesthetic studied. Local anesthetic effects on TXA2-induced early platelet aggregation (1-5 s) are unlikely to play a major role in the clinically observed antithrombotic effects of local anesthetics. ⋯ Local anesthetic effects on thromboxane A2-induced early platelet aggregation (1-5 s) are unlikely to play a major role in the clinically observed antithrombotic effects of local anesthetics. Thus, other potential targets need to be explored.
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Anesthesia and analgesia · Nov 2001
Anaphylactoid reactions after cisatracurium administration in six patients.
We report six cases of anaphylactoid reaction after the administration of the muscle relaxant cisatracurium. They include two first-time documented anaphylactoid reactions after a precurarising dose. These incidents challenge existing views of a substantially reduced anaphylactoid potential of cisatracurium relative to other muscle relaxants.
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Anesthesia and analgesia · Nov 2001
Case ReportsSubarachnoid block for a patient with progressive chronic inflammatory demyelinating polyneuropathy.
We report a case of successful administration of a spinal anesthetic to a patient with progressive chronic inflammatory demyelinating polyneuropathy (CIDP). There have been no reports of regional anesthetic management of patients with CIDP.
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Anesthesia and analgesia · Nov 2001
The interaction between intrathecal neostigmine and GABA receptor agonists in rats with nerve ligation Injury.
Nerve ligation injury may produce a pain syndrome that includes tactile allodynia. Reversal effects on tactile allodynia have been demonstrated after the intrathecal administration of gamma-aminobutyric acid (GABA) receptor agonists or cholinesterase inhibitors in rats. We examined the drug interactions between neostigmine and muscimol or baclofen in a rat model of nerve ligation injury. Rats were prepared with tight ligation of the left L5-6 spinal nerves and chronic intrathecal catheter implantation. Tactile allodynia was measured by applying von Frey filaments ipsilateral to the lesioned hindpaw. Thresholds for paw withdrawal were assessed. Neostigmine (0.3-10 microg), muscimol (0.1-10 microg), and baclofen (0.1-3.0 microg) were administered to obtain the dose-response curve and the 50% effective dose (ED(50)). Fractions of ED(50) values were administered intrathecally to establish the ED(50)s of drug combinations (neostigmine-muscimol and neostigmine-baclofen). The drug interactions were performed. Intrathecal neostigmine, muscimol, baclofen, and their combinations produced a dose-dependent increase in withdrawal threshold of the lesioned hindpaw. Both analyses revealed a synergistic interaction for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination was additive. These results suggest that the activation of both muscarinic and GABA(A) receptors is required for synergistic interaction. ⋯ This study indicates that drug interaction is synergistic for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination is additive. In a rat model of nerve ligation injury, neostigmine, muscimol, baclofen, and their combinations provide an antagonism on touch-evoked allodynia at the spinal level.