Intradermal compared with prick testing in the diagnosis of anaesthetic allergy

We have tested the hypothesis that intradermal testing is a more effective method for determining the drug responsible for anaesthetic anaphylactic reactions than prick testing in 212 consecutive patients, aged more than 10 yr, referred to an anaesthetic allergy clinic over a 4-yr period. The study was a prospective, non-randomized design. Intradermal testing was conducted using a previously described method and diluted drugs, and prick testing using undiluted drugs (with the exception of opioid analgesics which were diluted 1:10). The tests were performed on individual patients' forearms on the same occasion. Patients were followed-up to determine the results of subsequent anaesthesia and the difference between tests was analysed using kappa and tau statistics. There was 93% agreement overall between the paired tests. Which test detected the drug responsible was dependent on diagnostic criteria for positivity. The differences between the tests were not statistically significant. Using both tests improved predictability by 67% (tau = 0.67, P < 0.001). We conclude that in the absence of data to support one test being superior, other factors influence the choice of test. Prick testing was cheaper, and the reduction in pain and trauma with prick testing makes it more suitable for children. However, there are no data available on the safety of subsequent anaesthesia based on the results of prick testing alone, and reliability with time has not been assessed. Intradermal testing may be easier for the infrequent user. Skin testing is valuable in the investigation of anaesthetic anaphylaxis whichever test is chosen. When there is doubt both tests should be performed.      

Preliminary characterization of the procoagulant material in human ascites

Disseminated intravascular coagulation invariably accompanies placement of peritoneovenous (LeVeen) shunts, which suggests that ascitic fluid contains procoagulant material capable of activating blood coagulation. In this study, we identified thrombogenic activity in human ascites and the hemostatic pathway by which it acts. Peritoneal fluid was removed percutaneously from patients with ascites due to various causes. Four fractions were prepared by centrifugation: cells, a low-speed, cell-free fluid, a high-speed supernatant, and the precipitate from the high-speed centrifugation. Cellular fractions from all ascitic fluids shortened a one-stage clotting time of normal pooled plasma by 68% in comparison with saline solution and endotoxin controls. Similarly, the cell-free fluids also shortened the clotting time of normal pooled plasma by 41%. The cellular and cell-free fractions shortened the clotting time of factor VIII-deficient plasma but failed to demonstrate procoagulant activity in factor VII-deficient plasma. These fractions had no effect on platelet aggregation or the platelet release reaction. The high-speed precipitate was dissociated by ethylenediaminetetra-acetate (EDTA) into fluid phase and precipitate, both of which demonstrated procoagulant activity. Furthermore, high-speed precipitate contained protein, phospholipid, and sterol in proportions similar to those of plasma membranes and contained membrane-bound vesicles as identified by means of electron microscopy. This material could be rendered inactive by heating to 100 degrees C for 2 minutes or by incubation with phospholipase C for 15 minutes. Finally, the ability of the high-speed precipitate to shorten the clotting time was prevented by preincubation with a monoclonal antibody, which is known to inhibit the procoagulant activity of human tissue factor. We suggest that several entities contribute to the procoagulant properties of human ascites, with procoagulant material deriving at least in part from peritoneal cells. The sedimentable procoagulant factor appears to be associated with cellular membranes or membrane fragments and is thromboplastin-like in its chemical composition, immunoreactivity, and substrate specificity.     

Efficacy of prophylactic antibiotics in vascular surgery: an arterial wall microbiologic and pharmacokinetic perspective

This prospective study examined microbiologic features of arterial tissue and pharmacokinetics and bioactivity of cefamandole and cefazolin in patients undergoing elective primary prosthetic aortoiliofemoral/infrainguinal reconstruction. Double-blind, randomized, perioperative prophylaxis (1 gm intravenously every 6 hours for nine doses) with cefamandole or cefazolin was administered to 47 patients. Specimens of blood serum, subcutaneous fat, thrombus, atheroma, and arterial wall were obtained for culture and minimal inhibitory concentration and drug level analysis by high-pressure liquid chromatography. The serum half-life (hr +/- SEM) was 1.43 +/- 0.36 for cefamandole and 2.22 +/- 0.40 for cefazolin. Over the first 2 hours of surgery and for all time intervals combined, the serum concentration of cefazolin was significantly higher (p less than 0.025) than cefamandole. Irrespective of sampling time, the tissue concentration of cefazolin was significantly greater (p less than 0.005) than cefamandole. Positive arterial tissue cultures were obtained in 12 of 29 patients (41.4%) from 23 of 116 (19.8%) arterial tissue specimens. Coagulase-negative Staphylococcus was the predominant isolate, 64 of 93 (68.8%). Twenty-five of the 51 coagulase-negative staphylocci tested (49%) were slime-producers. During surgery, the arterial tissue concentration of cefamandole fell below the geometric mean minimal inhibitory concentration against all organisms combined, and against S. aureus (with the highest minimal inhibitory concentration of the prevalent isolates), significantly more often than the concentration of cefazolin. The data show that a significant number of primary elective aortoiliofemoral/infrainguinal reconstructions are associated with positive arterial tissue cultures, which represent a potential source of graft infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vein patch versus primary closure for carotid endarterectomy. A randomized prospective study in a selected group of patients

During a 4-year period, 136 patients undergoing 152 carotid endarterectomies consented to be randomized to primary or saphenous vein patch closure of the arteriotomy. At operation, before randomization, careful assessment of arterial dimensions and anatomy was made. Patients who had an internal carotid artery (ICA) diameter less than 5 mm, arteriotomy extending more than 3 cm beyond the origin of the ICA, or tortuous or kinked ICAs were not randomized; they received obligatory vein patch closure (necessary in 20% cases). All patients were followed up every 3 months for 1 year and every 6 months thereafter with duplex scanning, ocular pneumoplethysmography, and neurologic assessment. The incidence of atherosclerotic risk factors was equal in the groups and all except one of the patients were male. Perioperative morbidity was not significantly different among those having primary closure (n = 60), saphenous vein patch closure (n = 62), and obligatory vein patch closure (n = 30). Operative time among patients having primary closure (122 +/- 4 minutes) was significantly less (p less than 0.001) than among those having saphenous vein patch closure (150 +/- 3 minutes). Three perioperative strokes were evenly distributed among the groups (2% for all procedures); no deaths and no acute postoperative occlusions occurred. Recurrent disease occurred in 12.9% of patients having saphenous vein patch closure compared with its occurrence in 1.7% of those having primary closure (p less than 0.05). However, most recurrences were moderate stenoses (25% to 50% diameter reduction), all were smooth-surfaced, and none required a second operation. All except one of the recurrences among those patients with saphenous vein patch closure were in the bulb and the origin of the ICA; two had evidence of regression. This finding suggested that thrombus layering in the dilated part of the saphenous vein patch reconstruction was the cause. This study demonstrates that in men with carotid arteries of predetermined minimal dimensions undergoing carotid endarterectomy routine saphenous vein patch closure does not produce superior results, is associated with a higher incidence of early recurrence, and increases operative time. In selected patients with anatomic risk factors for recurrent disease or acute postoperative occlusion, saphenous vein patch closure is appropriate.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

Visual hallucinations on eye closure associated with atropine toxicity. A neurological analysis and comparison with other visual hallucinations

Visual hallucinations of remarkable intensity began shortly after intravenous atropine and persisted for 11 days. They were present only when the eyes were closed and were associated with heightened dreaming and disturbed sleep. The patient remained lucid and described his experiences to his attendants. Our patient's hallucinations bore some resemblance to hypnagogic hallucinations and this became the basis for the hypothesis that the hallucinations originated in the sleep-dream system of the brain stem. It is speculated that a similar site--a metabolic locus minoris resistentiae may play a part in other types of visual hallucinations and in delirium.     

Physiologically based pharmacokinetic modeling of the pregnant rat: a multiroute exposure model for trichloroethylene and its metabolite, trichloroacetic acid

A physiologically based pharmacokinetic (PB-PK) model was developed to describe trichloroethylene (TCE) kinetics in the pregnant rat exposed to TCE by inhalation, by bolus gavage, or by oral ingestion in drinking water. The kinetics of trichloroacetic acid (TCA), an oxidative metabolite of TCE, were described by a classical one-compartment pharmacokinetic model. Among the required model parameters for TCE, partition coefficients (PCs) and kinetic constants for oxidation were determined by vial equilibration and gas uptake methods, respectively. The fat:blood PC was 33.9; the blood:air PC was 13.2; and the fetal tissue:fetal blood PC was 0.51. TCE was readily metabolized with high substrate affinity. In naive and pregnant female rats the maximum velocities of oxidative metabolism were 10.98 +/- 0.155 and 9.18 +/- 0.078 mg/kg/hr, while the estimated Michaelis constant for the two groups of rats was very low, 0.25 mg/liter. The first-order rate constant for oral absorption of TCE from water was 5.4 +/- 0.42/hr-1 in naive rats. With TCA, the volume of distribution (0.618 liter/kg) and the plasma elimination rate constant (0.045 +/- 0.0024/hour) were estimated both from intravenous dosing studies with TCA and from an inhalation study with TCE. By comparison of the two routes of administration, the stoichiometric yield of TCA from TCE was estimated to be 0.12 in pregnant rats. To develop a data base for testing the fidelity of the PB-PK model, inhalation and bolus gavage exposures were conducted from Day 3 to Day 21 of pregnancy and a drinking water exposure from Day 3 to Day 22 of pregnancy. Inhalation exposures with TCE vapor were 4 hr/day at 618 ppm. The TCE concentration in drinking water was 350 micrograms/ml and the gavaged rats received single daily doses of 2.3 mg TCE/kg. Time varying physiological parameters for compartment volumes and blood flows during pregnancy were obtained from the published literature. Using the kinetic parameters determined by experimentation, TCE concentrations in maternal and fetal blood and TCA concentrations in maternal and fetal plasma were predicted from the PB-PK model by computer simulation and compared favorably with limited data obtained at restricted time points during pregnancy for all three routes of exposure. On the basis of the PB-PK model, fetal exposure to TCE, as area-under-the-curve, ranged from 67 to 76% of maternal exposure. For TCA the fetal exposure was 63 to 64% of the maternal exposure. The fetus is clearly at risk both to parent TCE and its TCA metabolite.(ABSTRACT TRUNCATED AT 400 WORDS)     

Left atrial myxoma: diagnosis by digital subtraction intravenous angiography

Digital subtraction intravenous angiography (DSIVA) represents an important technical advance in angiographic diagnosis. Herein we present three patients with left atrial myxoma assessed by DSIVA. We review the role of DSIVA in evaluation of patients with suspected cardiac tumors and the importance of careful atrial-phase scrutiny in examinations obtained for other purposes (ie, pulmonary angiography and assessment of ventricular function).