Complications after total thyroidectomy

A retrospective review of 64 total thyroidectomies performed at Memorial Sloan-Kettering Cancer Center was conducted. Only one patient had permanent hypocalcemia (1.6%) requiring calcium supplementation. Eight patients had a total of 11 complications, for a complication rate of 12.5%. These results are in sharp contrast to those published in 1972 from this institution, in which the permanent hypocalcemia rate was 29%. The reasons for this difference are discussed.     

Activation of misonidazole by rat liver microsomes and purified NADPH-cytochrome c reductase

Rat liver microsomes and purified NADPH-cytochrome c reductase metabolized [14C]misonidazole anaerobically to a reactive intermediate that covalently binds to tissue macromolecules. Air strongly inhibited the binding whereas carbon monoxide had no effect, indicating that misonidazole is activated via reduction and not by cytochrome P-450-dependent oxidation. Both systems showed an absolute requirement for NADPH and were stimulated by flavine (FAD) and paraquat. The apparent Km for misonidazole binding to microsomal protein was 0.74 mM the apparent Vmax was 0.64 nmole 14C bound . mg-1 . min-1. At a single substrate concentration, nitrofurantoin, nitrofurazone and desmethylmisonidazole inhibited the covalent binding of misonidazole to microsomal protein by 47, 26, and 38% respectively. The effect of nitrofurantoin on the kinetics of misonidazole binding gave a complex interaction indicative of uncompetitive inhibition. Glutathione reduced the binding of misonidazole to microsomal protein below the level observed for boiled microsomes while ascorbic acid had no effect. Compared to nitrofurantoin and paraquat, misonidazole was a poor stimulator of superoxide production as measured by adrenochrome formation.     

Pharmacokinetics of intravenous dantrolene in children

To determine the pharmacokinetics of iv dantrolene and its metabolites in children, ten children 2-7 yr of age scheduled for minor elective surgery, were studied. After induction of anesthesia and tracheal intubation, dantrolene (2.4 mg/kg) was administered iv over 10.2 +/- 0.83 min. Venous blood samples (3 ml) were obtained 1, 5, 10, 20, and 30 min and 1, 2, 4, 8, 12, and 20 h after the dantrolene infusion. Whole blood concentrations of dantrolene, 5-hydroxydantrolene, and nitroreduced acetylated dantrolene were measured by high-performance liquid chromatography. The whole blood concentration of dantrolene decreased rapidly from a mean (+/- SD) of 6.03 +/- 0.93 microgram/ml 1 min after the end of the dantrolene infusion to 3.56 +/- 0.49 microgram/ml at 1 h. Between 1 and 4 h, the concentration of dantrolene either remained constant or increased slightly. Thereafter, the concentration of dantrolene decreased slowly with an elimination half-life (mean +/- SD) of 10.0 +/- 2.6 h. The mean (+/- SD) time for the concentration of dantrolene to decrease to 3.0 micrograms/ml was 6.55 +/- 2.88 h. The whole blood concentration of 5-hydroxydantrolene reached a maximum of 0.60 +/- 0.18 microgram/ml approximately 7 h after the dantrolene and decreased thereafter with an elimination half-life of 9.0 +/- 2.5 h. The concentration of nitroreduced acetylated dantrolene was below the limit for detection at all times. All children recovered without complications. Intravenous dantrolene, 2.4 mg/kg, produces safe and predictable blood concentrations in children similar to those reported in adults.     

The Dose-Response Relationship of Tranexamic Acid

Background: Prophylactic administration of the antifibrinolytic drug tranexamic acid decreases bleeding and transfusions after cardiac operations. However, the best dose of tranexamic acid for this purpose remains unknown. This study explored the dose-response relationship of tranexamic acid for hemostatic efficacy after cardiac operation.

Methods: In prospective, randomized, double-blinded fashion, 148 patients undergoing cardiac operation with extracorporeal circulation were divided into six groups: a placebo group and five groups receiving tranexamic acid in loading doses before incision (range 2.5 to 40 mg *symbol* kg sup -1) and one-tenth the loading dose hourly for 12 h. The mass of blood collected by chest tubes over 12 h represented blood loss. Allogeneic transfusions within 12 h and within 5 d of surgery were tallied.

Results: The six groups presented similar demographics. Patients receiving placebo had increased postoperative D-dimer concentration compared to groups receiving tranexamic acid. Patients receiving at least 10 mg *symbol* kg sup -1 tranexamic acid followed by 1 mg *symbol* kg sup -1 *symbol* h sup -1 bled significantly less (365, 344, and 369 g *symbol* 12 h sup -1, respectively, for those three groups) compared with patients who received placebo (522 g, P < 0.05). Tranexamic dose did not affect transfusions. Only initial hematocrit affected whether a patient received an allogeneic transfusion within 5 days of operation (odds ratio 2.08 for each 3% absolute decrease in hematocrit).     

How optometrists screen for glaucoma: A survey

All optometrists registered and practising in Leicestershire were surveyed to find out what facilities they have for glaucoma screening, how patients are selected for screening, what tests are performed, and the criteria used for referring patients to the hospital ophthalmic service. All respondents examine the optic disc of all patients: 99% have tonometry available, but most use it selectively, on the basis of age, family history and disc appearance. Although 88% have field testing apparatus, this is usually not of a type likely to be effective in screening a general population: 38% have automated or semiautomated perimetry. The criterion level of IOP at which 80% of respondents would refer was 27 mm Hg in the absence of disc cupping, falling to 24 mm Hg if cupping was suspected. Over 80% would refer any patient with a field defect irrespective of IOP.     

Rotational remodeling of malrotated femoral fractures: a model in the rabbit.

It is estimated that 20-40% of femoral fractures in children heal in malrotation, yet few patients later complain. To determine if malrotation corrects spontaneously, midshaft osteotomies were made in femurs of 16 rabbits aged 8 weeks and the distal fragments were internally rotated 45 degrees, where they were held with external fixators. The animals were killed between week 0 and week 17. Version of the femoral necks was determined by computed tomography scan (CT). The version altered rapidly toward normal from weeks 0 to 4 and then remained stable, with an average rotational remodeling of 55%.