Cardiovascular collapse during anesthesia in a patient with preoperatively discontinued chronic MAO inhibitor therapy

We describe a patient in whom long-term monoamine oxidase (MAO) inhibitor therapy was discontinued 20 days before surgery with general anesthesia. This patient developed severe perioperative hypotension after administration of 10 mg of bupivacaine through an epidural catheter, which was corrected only after potent vasopressor therapy. We attribute this hemodynamic instability to attenuation of this patient's sympathetic tone based on several mechanisms: (1) residual effect of long-term administration of MAO inhibitor that caused a decrease in the number of β-adrenergic receptors (adrenergic subsensitivity due to receptor down-regulation), (2) recovered MAO activity causing effective degradation of sympathetic amines, and (3) combined attenuating effects of general and epidural anesthesia on sympathetic tone.     

Dendritic arbors of large-field ganglion cells show scaled growth during expansion of the goldfish retina: a study of morphometric and electrotonic properties

The retina of the goldfish grows by a balloon-like expansion and by the addition of new neurons at the margin. It has been proposed that as a consequence of this expansion the dendritic arbors of ganglion cells in central retina grow in a uniform manner without the addition of new branches. In the present study, we have examined this proposal by comparing the geometries of individual dendritic arbors of large-field ganglion cells from the retinas of small/young and large/old fish. These comparisons were based on measurements of several parameters of dendritic morphology, including number of segments and branches, branch angles, changes in diameter at branch points, and proximal versus distal distribution of arbor length. In addition, we used passive, steady-state cable modeling as an independent method of estimating the functional architectures of small and large dendritic arbors. Our morphometric data indicate that, though they are very different in absolute size, dendritic arbors of small and large ganglion cells have remarkably similar architectures. Analysis with steady-state cable equations indicates that the arbors from small and large cells have equivalent electrotonic lengths and show comparable propagation of synaptic currents. These data are consistent with the hypothesis that dendritic arbors of small and large ganglion cells are scaled versions of one another. We conclude that the growth of these cells during the expansion of the retina is the result of the addition of dendritic mass to an arbor whose basic geometry remains unchanged.     

Iotrol versus metrizamide in lumbar myelography: a double-blind study

In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.     

The incidence of postoperative nausea and vomiting: a retrospective comparison of alfentanil versus sufentanil.

Postoperative nausea and vomiting have been associated with the use of intravenous narcotics, and nitrous oxide may worsen the emetic effects of narcotics. Alfentanil and sufentanil are two synthetic derivatives of fentanyl; alfentanil has a shorter wake-up time than fentanyl, and sufentanil is equivalent to fentanyl. In order to study comparative emetic properties of these two drugs, patients in two different cities were randomly allocated to two different groups and retrospectively compared. Group I received sufentanil N2O/O2 with 0.25% isoflurane. Group II received alfentanil N2O/O2 with 0.25% isoflurane. With group I, the overall incidence of nausea was 31% and of vomiting was 6.2%. For group II, the overall rate for nausea was 38.2% and 8.8% for vomiting. Statistically, there was no significant difference in nausea or vomiting between groups.