Anesthesia and analgesia
-
Anesthesia and analgesia · Oct 2002
Case ReportsDissociative mental state in a patient with an intrathecal drug administration system.
We describe a patient with acute mental status changes, which resolved on removal of medication from the reservoir of a Synchromed intrathecal pump. This report highlights the potential adverse mental affects of chronic spinal infusions for pain therapy and discusses pitfalls in toxicology analysis using immunoassay.
-
Anesthesia and analgesia · Oct 2002
Randomized Controlled Trial Comparative Study Clinical TrialRemifentanil, fentanyl, and cardiac surgery: a double-blinded, randomized, controlled trial of costs and outcomes.
Remifentanil may be beneficial in patients undergoing coronary artery bypass graft surgery, by promoting hemodynamic stability, reducing drug requirements, and attenuating the neurohumoral "stress response." We enrolled 77 cardiac surgical patients in a double-blinded, randomized trial and randomly allocated them to one of three groups: remifentanil infusion at 0.83 micro g. kg(-1). min(-1) (Group R); fentanyl bolus, small dose, at 12 micro g/kg (Group FLD); and fentanyl bolus, moderate dose, at 24 micro g/kg (Group FMD). We found a significant difference in the median time to tracheal extubation: Group FLD, 6.5 h; Group R, 7.3 h; and Group FMD, 9.7 h (P = 0.025). Group R patients had similar times to those of Groups FLD (P = 0.14) and FMD (P = 0.30). Group FLD patients had a longer length of hospital stay (P = 0.030). Patients in Group R had a significantly infrequent rate of hypertension but a frequent rate of hypotension (P < 0.01). The urinary cortisol excretion was larger in Group FLD patients (P < 0.0005), and urine flow was smaller (P < 0.0005). Remifentanil was associated with a propofol dose reduction (P = 0.0005) and a concomitant higher bispectral index (P = 0.032). Three Group FLD patients, but none in groups FMD and R, had postoperative myocardial infarctions (P = 0.032). Remifentanil has larger drug acquisition costs but does not increase the total hospital costs associated with cardiac surgery. ⋯ Remifentanil did not significantly reduce the duration of tracheal intubation after cardiac surgery. Remifentanil, when compared with fentanyl (total doses of approximately 15 and 28 micro g/kg), blunts the hypertensive responses associated with cardiac surgery but is associated with more hypotension; when compared with fentanyl 15 micro g/kg, remifentanil reduces cortisol excretion. Larger-dose opioids (remifentanil 0.85 micro g. kg(-1). min(-1) or fentanyl 28 micro g/kg) were associated with a decreased rate of myocardial infarction after cardiac surgery.
-
Anesthesia and analgesia · Oct 2002
A neurosteroid anesthetic, alphaxalone, inhibits nicotinic acetylcholine receptors in cultured bovine adrenal chromaffin cells.
Several lines of evidence suggest that nicotinic acetylcholine receptors (nAChRs) are a target of general anesthetics. Alphaxalone (5alpha-pregnan-3alpha-ol-11, 20-dion) is a neurosteroid, which was used clinically for anesthesia, but its effects on the function of nAChRs have not been well investigated. We examined the effects of alphaxalone on nAChRs in cultured bovine adrenal chromaffin cells. We studied the effects of alphaxalone on nicotine-induced increases in the cytosolic Ca(2+) concentration ([Ca(2+)](i)) and on membrane currents using Ca(2+)-imaging and whole-cell patch-clamp techniques, respectively, in these cells. We also examined the effects of alphaxalone on gamma-aminobutyric acid A receptors in the same cells and compared them with the effects on nAChRs. Alphaxalone (0.1-100 micro M) inhibited nicotine-induced [Ca(2+)](i) increases in a concentration-dependent manner. Alphaxalone inhibited high K(+)-induced [Ca(2+)](i) increases, but the inhibition was observed only at 100 micro M. In voltage-clamp experiments using negative holding potentials, alphaxalone (0.1-100 micro M) itself induced inward currents, which were abolished by the gamma-aminobutyric acid A receptor antagonist picrotoxin. Alphaxalone also inhibited nicotine-induced inward currents, and the inhibition was unaffected by picrotoxin. We conclude that alphaxalone, at anesthetic concentrations, inhibits nAChRs in adrenal chromaffin cells. Alphaxalone may affect the sympathetic and other nervous systems via inhibition of nAChRs. ⋯ Alphaxalone inhibits the function of nAChRs at clinically relevant concentrations in adrenal chromaffin cells. Thus, the present findings may provide some information for understanding the anesthetic mechanism of alphaxalone.
-
Anesthesia and analgesia · Oct 2002
Randomized Controlled Trial Comparative Study Clinical TrialFour-injection brachial plexus block using peripheral nerve stimulator: a comparison between axillary and humeral approaches.
We conducted this prospective, randomized study to compare the success rate, performance time, and onset time of surgical anesthesia of a four-injection brachial plexus block performed at the axillary (Group Axillary; n = 50) or at the humeral (Group Humeral; n = 50) level using a peripheral nerve stimulator. All patients received 40 mL of a mixture of equal parts of 0.5% bupivacaine and 2% lidocaine. Four patients in Group Axillary and two in Group Humeral were excluded from the study because all of the four nerves were not localized in the allotted time. The incidence of complete block (91% versus 89%), defined as block of all the sensory areas below the elbow, and the onset time of sensory block (15 +/- 6 min versus 16 +/- 7 min) were not different between the groups. The performance time was shorter in Group Humeral (7 +/- 2 min versus 8 +/- 2 min; P < 0.005). Block performance pain was lower in Group Axillary patients (16 +/- 9 min versus 23 +/- 12 min; P < 0.005). For four-injection brachial plexus block, we conclude that both the axillary and the humeral approaches provide a high success rate and a rapid onset of sensory anesthesia; the differences found between the groups could be considered clinically unimportant. ⋯ Two methods of brachial plexus block using a nerve-stimulator were compared in a prospective study. A four-injection technique was performed at the axillary or at the humeral level. Both approaches provided a fast onset and a high success rate. The differences found between the groups could be considered clinically unimportant.