Cerebral injury after cardiac surgery: identification of a group at extraordinary risk. Multicenter Study of Perioperative Ischemia Research Group (McSPI) and the Ischemia Research Education Foundation (IREF) Investigators.

BACKGROUND AND PURPOSE: Cerebral injury after cardiac surgery is now recognized as a serious and costly healthcare problem mandating immediate attention. To effect solution, those subgroups of patients at greatest risk must be identified, thereby allowing efficient implementation of new clinical strategies. No such subgroup has been identified; however, patients undergoing intracardiac surgery are thought to be at high risk, but comprehensive data regarding specific risk, impact on cost, and discharge disposition are not available. METHODS: We prospectively studied 273 patients enrolled from 24 diverse US medical centers, who were undergoing intracardiac and coronary artery surgery. Patient data were collected using standardized methods and included clinical, historical, specialized testing, neurological outcome and autopsy data, and measures of resource utilization. Adverse outcomes were defined a priori and determined after database closure by a blinded independent panel. Stepwise logistic regression models were developed to estimate the relative risks associated with clinical history and intraoperative and postoperative events. RESULTS: Adverse cerebral outcomes occurred in 16% of patients (43/273), being nearly equally divided between type I outcomes (8.4%; 5 cerebral deaths, 16 nonfatal strokes, and 2 new TIAs) and type II outcomes (7.3%; 17 new intellectual deterioration persisting at hospital discharge and 3 newly diagnosed seizures). Associated resource utilization was significantly increased--prolonging median intensive care unit stay from 3 days (no adverse cerebral outcome) to 8 days (type I; P<0.001) and from 3 to 6 days (type II; P<0.001), and increasing hospitalization by 50% (type II, P=0.04) to 100% (type I, P<0.001). Furthermore, specialized care after hospital discharge was frequently necessary in those with type I outcomes, in that only 31% returned home compared with 85% of patients without cerebral complications (P<0.001). Significant risk factors for type I outcomes related primarily to embolic phenomena, including proximal aortic atherosclerosis, intracardiac thrombus, and intermittent clamping of the aorta during surgery. For type II outcomes, risk factors again included proximal aortic atherosclerosis, as well as a preoperative history of endocarditis, alcohol abuse, perioperative dysrhythmia or poorly controlled hypertension, and the development of a low-output state after cardiopulmonary bypass. CONCLUSIONS: These prospective multicenter findings demonstrate that patients undergoing intracardiac surgery combined with coronary revascularization are at formidable risk, in that 1 in 6 will develop cerebral complications that are frequently costly and devastating. Thus, new strategies for perioperative management--including technical and pharmacological interventions--are now mandated for this subgroup of cardiac surgery patients.

Influence of packaging and processing conditions on the decontamination of laboratory biomedical waste by steam sterilization.

The conditions for optimal steam decontamination of polypropylene bags half loaded with laboratory biomedical waste were studied (276 bags were processed). Controls were single-closed bags without water added or incisions made in the top, standing freely in an autoclave set at 121 degrees C. The average time required to reach 121 degrees C at the load center was 46 min for controls. A significant increase in this time occurred following addition of water to bags without incisions (60 min), with double bagging (60 min), or when using vertical containers (82 min). A significant decrease occurred when bags were slashed (37 min) or processed at 123 degrees C (32 min) or 132 degrees C (19 min). Horizontal containers or addition of water to slashed bags had no significant effect.

Comparison of the fluorescent treponemal antibody absorption (FTA-ABS) test with the FTA-ABS double staining test for detection of antitreponemal immunoglobulin M in the 19S fraction of human serum.

A widely used immunoglobulin M (IgM) detection assay for the diagnosis of neonatal congenital syphilis is the fluorescent treponemal antibody absorption test used with fractionated serum (FTA-ABS 19S IgM test). Reading the results of the FTA-ABS test is more cumbersome than reading those of the FTA-ABS double staining (FTA-ABS-DS) test, a confirmatory test for specific IgG. To verify that the FTA-ABS-DS test used with an anti-human IgM conjugate could detect specific IgM in fractionated serum samples (FTA-ABS-DS 19S IgM test), 164 fractionated (QUIK-SEP IgM Isolation System; ISOLAB, Inc., Akron, Ohio) serum specimens from infected neonates or adults or from IgG-seronegative subjects were tested by both techniques. The sensitivity limits of the two tests were assessed with reactive serum samples diluted to an endpoint titer. Samples nonreactive by the FTA-ABS 19S IgM test (n = 74) were either nonreactive (n = 65), minimally reactive (n = 5), or reactive (n = 4) by the FTA-ABS-DS 19S IgM test. Samples minimally reactive by the FTA-ABS 19S IgM test (n = 32) were minimally reactive (n = 1) or reactive (n = 31) by the double staining test. All samples reactive by the FTA-ABS 19S IgM test (n = 58) were also reactive by the FTA-ABS-DS 19S IgM test. There was a directly proportional linear relationship (r = 0.9794) between titers obtained by both tests. FTA-ABS-DS 19S IgM titers were constantly equal to or higher than FTA-ABS 19S IgM titers. Fluorescence intensity reading repeatability was 91.4% for the FTA-ABS-DS 19S IgM test and 81.7% for the FTA-ABS 19S IgM test (P = 0.015). Because the more easily read FTA-ABS-DS 19S IgM test is at least as sensitive as, if not more sensitive than, the FTA-ABS 19S IgM test, it is a good alternative to the latter test for the detection of specific IgM in human fractionated sera for those using fluorescence microscopes with incident light.

Specificity of the microimmunofluorescence assay for the serodiagnosis of Chlamydia pneumoniae infections.

Chlamydia pneumoniae infections are mostly confirmed using an indirect microimmunofluorescence test for which potential cross-reactions between antigens from different chlamydial species are not well documented. Using this assay, 928 sera (507 subjects) submitted for Chlamydia pneumoniae serology were tested for specific IgM and IgG to this bacteria using the TW-183 antigen. IgM and IgG reactivities to Chlamydia trachomatis serotypes C, D, E, and L2 and Chlamydia psittaci strain 6BC antigens were also tested. A sample was interpreted as positive only when evenly fluorescent elementary bodies were observed. Twenty-five subjects (4.9%) showed serological evidence of recent Chlamydia pneumoniae infection (IgM positive and (or) IgG seroconversion); 11 of them also showed serological evidence of recent infection with at least one other chlamydial species. Specificity was 50 and 63% for IgM and IgG detection, respectively. These results suggest that mixed or temporally related infections might occur, or, more likely, that some Chlamydia pneumoniae IgM or IgG reactivities might be due to heterotypic antibodies.

Secondary immune response in a vaccinated population during a large measles epidemic.

The rates of secondary immune response (SIR) and secondary vaccine failure (SVF) during a measles epidemic (10,184 notifications) were evaluated. A patient with SIR was defined as a subject for whom all sera were immunoglobulin G (IgG) positive and IgM negative with a significant increase in complement fixation titer. A patient with SVF was defined as a vaccinated symptomatic subject showing a SIR. Sequential sera from 898 subjects were tested for measles antibody by enzyme-linked immunosorbent assay (IgG and IgM) and by complement fixation. Evidence of recent anti-measles virus specific immune response was found in 496 subjects (55.5%). The vaccination rate was estimated at 74.6% (99% confidence interval [CI], 67.9 to 80.7%). The number of exposed vaccinated subjects was estimated at 370 (74.6% of 496). The SIR rate was 4.03% (20 of 496) (99% CI, 2.1 to 6.9%) among subjects with immune response. These 20 subjects were 2 with measles (Centers for Disease Control's definition), 6 with measles with rash of unknown duration, 8 with presumed measles with either rash or fever, 3 asymptomatic subjects (2 with recent contact with a measles case), and 1 undocumented subject. Since 3 patients with SIR were asymptomatic and 2 others were documented as not vaccinated, there was a maximum of 15 probable occurrences of SVF among the 20 patients with SIR. The SVF rate among exposed vaccinated subjects was estimated at 4.05% (15 of 370) (99% CI, 1.9 to 7.5%). In conclusion, neither prior vaccination nor detectable SIR ensures protective immunity. Measles virus may induce asymptomatic SIR in IgG-seropositive subjects. SVF led to typical or modified measles but did not seem to have played an important role during this epidemic.

Performance and reliability of the Enzygnost measles enzyme-linked immuno-sorbent assay for detection of measles virus-specific immunoglobulin M antibody during a large measles epidemic.

Evaluation of the Enzygnost Measles Enzyme-Linked Immuno-Sorbent Assay kit (Behring) performance to detect specific immunoglobulin M (IgM) was carried out with 3,297 single serum samples and 898 paired serum samples collected during a measles epidemic (10,184 reported cases) in Quebec, Canada. Anti-measles IgM and IgG were detected by using the Enzygnost kit with the appropriate conjugates. Complement-fixing (CF) antibody (Ab) titers were assessed by the laboratory branch complement fixation micromethod. The Centers for Disease Control's clinical measles case definition was used. A modification of the manufacturer's optical density interpretation algorithm was introduced to allow for equivocal results, in addition to positive and negative ones. These three categories differed as to their association with a significant increase in CF Ab titer and the time between the onset of symptoms and phlebotomy. The IgM positivity rate for complement fixation-confirmed measles cases was 96.6% for vaccinated subjects and 100% for nonvaccinated subjects. The daily percentage of IgM seropositivity that was detected for subjects who became IgM positive within 30 days increased gradually from 40 to 90% for sera taken 1 to 7 days after the onset of symptoms, and it plateaued at 100% for sera taken 16 to 30 days after the onset of symptoms. IgM seropositivity was strongly associated with IgG seroconversion, CF Ab titer increase, and clinical measles (P less than 0.0001). Reproducibility was 100% for nonreactive sera and 99.1% for reactive sera. In conclusion, the Enzygnost Measles Enzyme-Linked Immuno-Sorbent Assay kit performed adequately to confirm measles virus infection during this epidemic. A second serum sample should be tested when an early-acute-phase serum sample is IgM negative.

DNA polymorphism among isolates from multiple sites of a patient with chronic herpes simplex virus, type 1 infection.

DNA polymorphisms among independent isolates of herpes simplex virus (HSV) type 1 were studied from a 7-year-old male patient with recurrent infections of the skin and internal organs. In the patient's serum, HSV antibodies could not be detected by complement fixation, enzyme-linked immunosorbent assay (ELISA), or neutralization tests. ELISA tests for the presence of antibodies to human immunodeficiency virus were also negative. One HSV isolate was obtained from mesenteric nodes biopsied in 1983; one from skin in 1984; and three (postmortem) from brain, lungs, and liver in 1985. Restriction enzymes Eco RI, Bgl II, Hind III, Kpn I, and Bam H1 digestion patterns of the five isolates were similar. However, Sal I digests of isolates from skin, mesenteric nodes, lungs, and liver showed variations that were distinct from that of the brain isolate. Although Sal I digests of skin, mesenteric nodes, lungs, and liver isolates share a common variation in lacking F and G, the liver isolate can be further differentiated because of the gain of a restriction site on the H fragment. Thus, the three distinct variants observed were the isolates from brain (variant 1); from skin, mesenteric nodes, and lungs (variant 2); and from liver (variant 3). The fragments involved in variations among these isolates (presence or absence of Sal, G and H) are from the unique short and long regions (invariable regions) of the genome and therefore do not show heterogeneity in size. The extent of variation among these isolates is less than that seen among epidemiologically unrelated strains, suggesting that they originated from a single infecting strain, probably the brain isolate.

Immunofluorescence assay for human immunodeficiency virus antibody: investigation of cell fixation for virus inactivation and antigen preservation.

Four cell fixation procedures were investigated for their abilities to inactivate human immunodeficiency virus (HIV) and preserve its antigenicity for antibody detection by immunofluorescence in MOLT-4-T4 cells. Air-dried cell smears were fixed in cold acetone, in acetone-methanol (1:1), in acetone-methanol (1:1) followed by 70% ethanol and then methanol, or in paraformaldehyde-acetone. Acetone alone did not inactivate cell-associated HIV, but the other three procedures did. HIV inactivation was achieved by storage of acetone-fixed cells at -70 degrees for 40 days. Antigenicity was measured by immunofluorescence assay titrations of selected human sera, a cerebrospinal fluid, and a gp41 monoclonal antibody. Acetone provided the best fixation as measured by fluorescence intensity and antibody titers. The other fixation methods all yielded weaker fluorescence signals and/or decreased titers. Acetone fixation and storage for 40 days at -70 degrees C provides safe and accurate immunofluorescence assay reagents.

Intrathecal morphine reduces the minimum alveolar concentration of halothane in humans.

The authors hypothesized that the analgesia provided by intraspinal opiates would decrease anesthetic requirement. To test this hypothesis, 20 women undergoing major gynecologic surgery were divided randomly into two groups. One group received 0.75 mg morphine sulfate intrathecally, and the other, the same dose intramuscularly (control), prior to the induction of anesthesia with halothane. MAC for halothane was 0.81% in the control group and 0.46% in the intrathecal morphine group (P = 0.024). The reduction in anesthetic requirement due to intrathecal morphine is greater than that produced by low to moderate doses of systemically administered opiates.

Performance and reliability of five commercial enzyme-linked immunosorbent assay kits in screening for anti-human immunodeficiency virus antibody in high-risk subjects.

Anti-human immunodeficiency virus enzyme-linked immunosorbent assay kits marketed by Electro-Nucleonics Inc. (ENI), Genetic Systems Corp. (GSC), Organon Teknika Inc. (OTI), Ortho Diagnostic Systems Inc. (ODSI), and Wellcome Diagnostics (WD) were evaluated by using 289 randomly selected serum samples from a high-risk population and 53 serum samples likely to produce false-positive results. The radioimmunoprecipitation assay was used as the reference test. Sensitivities ranged from 96.51% (ODSI, WD) to 97.67% (ENI, GSC, OTI). Sera showing antibodies to viral glycoproteins only produced the false-negative results. Specificities ranged from 99.6% (ENI, GSC, ODSI, OTI) to 100% (WD). False-positive results were obtained with sera from patients with autoimmune disease or Epstein-Barr virus infection. Only results from GSC and OTI kits were distributed in two compact clusters well segregated on either side of the cutoff point. ODSI and GSC kits had the best intralot reproducibility. The GSC kit had the best interlot reproducibility. Cutoff values for ODSI and GSC kits were the least variable. Intraplate repeatability was good for all kits. Sample localization was not an important source of variability. Our results do not point out one outstanding kit among the five evaluated. However, the GSC kit showed the best overall results.

Computerized analysis of antimicrobial drugs interactions in biological systems using an IBM-PC microcomputer.

We have developed a computer program to analyse the individual and combined effects of two treatments applied concurrently to a biological system. Analysis is done in regard to: level of significance selected for the statistical test (two-sided Student's t test); number of data available; expected combined effect resulting from addition (computed by the program); experimental hypothesis tested (synergism or antagonism). The main program gives access to eight options: input of new data; input of data from file; addition or modification to data in memory; display on monitor the results from analysis or the contents of a data file; analysis with another level of significance; printout; kinetics of interaction; end of program. The program is designed to work with an IBM-PC, Epson MX/FX 80/100 printer and Roland DXY 800 plotter. Sample runs are given.

Elimination of plasmidic resistance to ampicillin and of enterotoxinogenicity in certain enteric gram-negative bacteria after incubation with high concentrations of amprolium.

We have observed that treatment with high concentrations of a thiamine analog (amprolium) can lead to the elimination of the plasmidic resistance to ampicillin and the production of enterotoxin in wild Escherichia coli strains and in E coli and Salmonella typhimurium strains which had received the pKM101 plasmid through bacterial conjugation. By computer analysis, we also have determined that there is a highly significant (P less than 0.01) synergism between ampicillin and amprolium which reduces considerably the growth of certain enteric bacterial strains which have a plasmidic resistance to ampicillin and which were not markedly affected by amprolium alone, in our experimental conditions. Our data indicate that the rate of loss of the plasmid pKM101 after treatment of R+ bacterial strains with amprolium can be increased.

Estimation of endpoints in biological systems.

A program, written in BASIC, has been developed to estimate rapidly endpoints from a small number of experimental data. The computational method is based on the work of Reed and Muench (Am. J. Hyg. 27, 493 1938). Several endpoints may be estimated in the same run. A subroutine allows the saving of experimental data in disk file and a printout subroutine permits different types of printout (tabular or graphical). Estimation of several infectious doses (ID) of a guinea-pig inclusion conjunctivitis (GPIC) Chlamydia psittaci strain is given as sample run.

Analysis of interactions between treatments applied concurrently onto biological systems.

A program, written in BASIC, has been developed to analyse results of experiments studying individual and combined effect of two treatments (physical or chemical) on a biological system. Analysis is done in regard to: (1) level of significance selected for statistical test; (2) number of data available; (3) expected combined effect of treatments resulting from addition which is computed using an original formula; (4) experimental hypothesis tested. Using this program we have determined that there is a highly significant synergism between ampicillin (antibiotic) and amprolium (antiparasitic drug) to reduce the growth of some enteric bacterial strains which have a plasmidic resistance to ampicillin. Other applications are suggested.

Pulmonary, chest wall, and lung-thorax elastances in acute respiratory failure.

The usefulness of lung-thorax compliance (or elastance) as an index of pulmonary compliance (or elastance) was examined in 15 patients being ventilated for acute respiratory failure. Mean lung-thorax elastance (ELT) was 27.9 +/- 2.6 cm H2O/L, and the chest wall accounted for 34 +/- 2 percent of the mean total value. Changes in ELT caused by increments of positive end-expiratory pressure correlated only with changes in pulmonary elastance (r = 0.96; P less than 0.001) and not with chest wall elastance, although individual patients varied as to the contribution of the chest wall component. Lung-thorax elastance increased in direct proportion (1:1) to increases in pulmonary elastance, whereas the changes in lung-thorax compliance were only half those in pulmonary compliance. We conclude that elastance is a more useful clinical index than compliance.

Multipatient anesthetic mass spectrometry: rapid analysis of data stored in long catheters.

A centrally located mass spectrometer sequentially samples airway gases from ten anesthetized patients through 30 m long, 1.07 mm, ID, nylon catheters and three way solenoid valves. End-tidal and inspired concentrations of O2, N2, CO2, N2O, and halothane, enflurane, or isoflurane are displayed on a computer terminal screen in each OR with trend plots. While a gas sample from one room is being analyzed, all other catheters are slowly sampled in order to continuously store 20-s concentration profiles ready for analysis. The stored gas sample is analyzed at twice the rate it was sampled. The computer switches catheters after one breath has been validated from two comparable end-tidal PCO2 values. Large flow changes produced by switching from one catheter to the next require regulation of the pump pressure in the mass spectrometer. This method reduces the time required to sample each room to 6.96 s (4-10 rooms). Catheter transit slows the response to a step increase in concentration by about 0.13 s (from 10 per cent-90 per cent) and prolongs the transit time through the catheter for a volatile anesthetic by about 0.04 s more than N2. The monitoring facility is used in each room for an average of 5.5 h/day. Two years of experience suggest that it can facilitate detection of faulty technique and equipment, reduce cost of anesthetic agents by encouraging use of closed systems, increase patient safety, aid research and teaching, and diminish exposure of OR personnel to anesthetics. Inherent problems have resulted in an inoperative time of less than 2 per cent.

[Inapparent persistent chlamydial infection in McCoy cells]. / Infection chlamydiale persistante non apparente, dans des cellules de McCoy.

We have studied the phenomena of inapparent chlamydial infections in vitro using McCoy cells in culture as hosts and low doses of Chlamydia psittaci (GP-IC) as infecting agents. The results indicate that GP-IC can persist undetected at least 220 hrs in McCoy cells previously inoculated with 0.2 mL of a GP-IC preparation containing 30 ifu/mL, using the centrifuge-assisted inoculation technique. These cells were maintained in complete MEM medium supplemented with 2% v/v of foetal bovin serum (FBS). These inapparent chlamydial infections did not follow active infections (detectable chlamydial multiplication); however, they could be induced to active infections (formation of intracytoplasmic inclusions) by transfering the infected McCoy cells in complete MEM medium supplemented with 5% v/v of FBS and 1 microgram/mL of cycloheximide. Transfer of these cells in complete MEM medium supplemented with 5% v/v of FBS but without cycloheximide did not induce active infections indicating that nutritional competition was not implicated in these inapparent chlamydial infections since that medium usually support chlamydial multiplication.

Measurement of functional residual capacity during mechanical ventilation by simultaneous exchange of two insoluble gases.

A precise method for rapid measurement of functional residual capacity (FRC) during mechanical ventilation that uses the simultaneous exchange of argon and nitrogen is described. Circuit leaks were immediately recognizable upon completion of a run, and pneumotachygraphic inaccuracies due to turbulent flows, changes in viscosity, and time delays between pneumotachygraph and mass spectrometer signals were avoided. For 166 duplicate determinations, the first measurement of FRC differed from the second by 0.5 +/- 0.5 per cent (mean +/- SE). The technique does not affect pulmonary gas exchange. During 35 consecutive determinations of FRC (with an inspired oxygen of 50 per cent), mixed expired oxygen and carbon dioxide tensions varied less than 7 and 1.5 torr, respectively.