Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1995
Comparative StudyProlongation of spinal anesthesia with bupivacaine-loaded (DL-lactide) microspheres.
There is considerable interest in developing a sustained-release local anesthetic formulation to provide long-lasting anesthesia and to decrease systemic toxicity. Bupivacaine (B), 10 mg, loaded in two different types of polylactide microspheres (PLA1 and PLA2) was evaluated after spinal injection and compared with plain bupivacaine (pB), 2 mg. Experiments were performed in six New Zealand rabbits. ⋯ There was no significant difference in maximum B plasma concentration between pB and PLA1 (326 +/- 81 mg/mL vs 321 +/- 57 ng/mL). The time taken to reach the maximum plasma concentration (6.6 +/- 2.6 min vs 41.7 +/- 20.4 min; P < 0.05) was significantly different. This study demonstrated that the use of bupivacaine-loaded (DL-lactide) microspheres can prolong spinal motor block.
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Anesthesia and analgesia · Jul 1995
Comparative StudyHeparin neutralization by recombinant platelet factor 4 and protamine.
Protamine is the only available drug to reverse heparin-induced anticoagulation. Platelet factor 4 (PF4) is a basic polypeptide stored in platelets that reverses heparin. To investigate its potential as a reversal drug, we studied recombinant PF4 on anticoagulated blood obtained during cardiac surgery. ⋯ PF4 reversal ratios of 3:1 and 3.5:1 and protamine reversal ratios of 1:1, 1.5:1, 2:1 were not statistically different from heparinase-ACT values. There were no significant differences in viscoelastic measurements of clot formation between protamine and PF4. Recombinant PF4 at a 3.0:1 ratio reverses heparin-induced anticoagulation after cardiopulmonary bypass, and represents a potential alternative, especially for the protamine allergic patient.
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Several cases of unexpected high carboxyhemoglobin (COHb) levels in patients undergoing general anesthesia were observed. To avoid carbon monoxide (CO) intoxication, the use of high fresh gas flows and frequent changes of the absorbent were recommended. However, due to economic and ecologic considerations, low-flow anesthetic techniques have advantages. ⋯ As recently revealed, only dry absorbents produce CO if exposed to volatile anesthetics containing a CHF2-moiety. Thus, all measures must be avoided that dry out the absorbent. Low-flow anesthesia preserves the moisture content of the absorbent and, thus, seems to be a factor protecting from CO generation.