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BACKGROUND: Recent evidence suggests that early extubation after cardiac surgery can be performed without increased morbidity, resulting in economic advantages. However, most studies on this subject exclude patients with preoperative risk factors described as predictors for prolonged mechanical ventilation. The purpose of our prospective clinical trial was to decide whether early extubation is feasible independent of preoperative patient status, in particular independent of preoperative risk factors. METHODS: From 12/96 to 6/97, 266 patients underwent cardiac surgery, most commonly CABG and valve replacement. 65 patients (24.4%) formed the risk group, showing preoperatively at least one of the following risk factors: emergency surgery, severe left-ventricular dysfunction, previous heart surgery, recent myocardial infarction, age 75 years or older, history of several myocardial infarctions. The remaining 201 patients (75.6%) formed the control group. The percentage of patients extubated within 12 hours represented the primary endpoint. 38 patients (10 risk, 28 control) had to be excluded from further analyses due to intra- or perioperative complications. RESULTS: No differences between 55 risk patients and 173 control patients could be detected in extubation rate within 12 hours (100% vs 100%), mean extubation time (6:04 h vs 6:01 h), and incidence of complications after extubation (5.5% vs 5.2%). Risk patients were discharged 0.33 days later from the intensive care unit (2.00 d vs 1.67 d; p = 0.047). CONCLUSIONS: 1. All patients are basically suitable for early extubation, with the presence of preoperative risk factors used in this study being poor predictors of prolonged ventilation. 2. The necessity of prolonged ventilation is primarily determined by intra- or perioperative complications.

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Nonthoracotomy lead systems for implantable cardioverter defibrillators (ICDs) have reduced operative mortality and morbidity as compared to epicardial lead systems but are usually associated with higher defibrillation thresholds (DFTs). The purpose of this prospective randomized trial was to investigate if the second defibrillation electrode in the left subclavian vein can increase defibrillation efficacy and decrease DFT as compared to the superior vena cava (SVC) position in nonthoracotomy lead systems for ICDs. Seventeen patients (mean age: 49.9 +/- 11.3 years, mean ejection fraction: 46.1% +/- 15.8%) were implanted with an investigational unipolar electrode (Medtronic 13001) used as the defibrillation anode. DFT testing was started in the SVC (n = 10, group A) or the left subclavian vein (n = 7, group B), and repeated in the alternative position starting at the DFT of the initial position. Fifteen patients were eligible for analysis (group A: n = 9, group B: n = 6). With the electrode in the SVC, ventricular fibrillation could be successfully terminated in 9 out of 15 patients (60%). In the left subclavian vein the success rate was 100% (P < 0.01). Mean DFT in the SVC was 13.0 +/- 5.2 J and in the left subclavian vein 10.2 +/- 4.9 J. DFTs in the left subclavian vein were either lower (group A: n = 5/9, group B: n = 5/6) or equal to the results in the SVC position (P < 0.001). Thus, the left subclavian vein appears to be a superior alternative for positioning of the defibrillation anode as compared to the SVC for nonthoracotomy lead systems using two separate leads.

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Hypersensitivity reactions to heparin preparations with a wide spectrum of clinical manifestations have been reported frequently in the past, but are a rarity now. A 88 year old man was admitted for physical therapy of a collum femoris fracture. Treatment with a diuretic, Reserpine and Verapamil was continued. Chest x-ray revealed a large thoracic aortic aneurysm. From the 12th to the 18th day of low dose heparin prophylaxis with calcium heparin, 7500 U twice daily, at least eight attacks of asthma or cyanosis were observed, starting about two hours after heparin injection. The last attack began suddenly with wheezing, tachypnoea and cough and was associated with apprehension, a sudden blood pressure increase and severe cyanosis. Ventilation improved with oxygen and a beta 2-stimulator, but hypertension and cyanosis lasted for three hours. After discontinuation of heparin no further attacks occurred. Causes other then heparin could not be found. Despite the use of porcine mucosa heparin, avoidance of preservatives and use of low doses a hypersensitivity reaction occurred in our case. The delayed onset after preceding subcutaneous application as well as difficulties in separating the reaction from complications of underlying disease may delay heparin discontinuation.

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This paper summarises the results of the evaluation of an enzyme immunoassay for thyrotropin by a group of 17 laboratories. This sandwich enzyme immunoassay is based on the specific binding of the beta-subunit of thyrotropin by monoclonal antibodies coated on polystyrene tubes. Thyrotropin, bound to the tube wall, is determined with horse radish peroxidase coupled to the Fab fragment of a polyclonal sheep antibody against the alpha-subunit of thyrotropin. The lower limit of detection of 0.5 mU/1 was adequate, and the precision of the enzyme immunoassay was comparable with that found in radioimmunoassays for thyrotropin. The intraassay CV was in the range of 2 to 10% for a serum containing 1.5 to 5 mU/1 thyrotropin. The interassay CV was in the range of 5 to 10% for a serum containing about 6 mU/1. The recovery of thyrotropin standards in human thyrotropin-free serum was between 93% and 101%. Cross-reactions with human choriongonadotropin and gonadotropins were excluded. There were no interferences in haemolytic and lipaemic samples or by high bilirubin concentrations. Comparison of thyrotropin levels measured with different radioimmunoassays and with the enzyme immunoassay gave correlation coefficients in the range of 0.925 and 0.995. Advantages of the enzyme immunoassay are the absence of radioactive substances and the short incubation period of 3 hours. Incubation overnight results in a higher sensitivity of 0.18 mU/1. This assay can therefore be regarded as one of the new highly sensitive thyrotropin assays (Bernutz, C. et al. (1985) Clin. Chem. 31, 289-292).

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Excretion of 2,3-dinor-6-ketoprostaglandin F1 alpha and 2,3-dinorthromboxane B2, the main urinary metabolites of prostacyclin and thromboxane, was evaluated by gas chromatography-mass spectroscopy and radioimmunoassay, respectively, at various conditions in man. In healthy young males excretion of 2,3-dinor-6-ketoprostaglandin F1 alpha was of little variability, whereas urinary 2,3-dinorthromboxane B2 showed marked interindividual but moderate intraindividual variations. The ratio of urinary 2,3-dinorthromboxane B2 to thromboxane B2 in young males was about 15. Excretion of 2,3-dinor-6-ketoprostaglandin F1 alpha in women of reproductive age was higher (155 +/- 23 ng/g creatinine, P less than 0.005) than in postmenopausal women (97 +/- 24 ng/g creatinine) and in men (78 +/- 7.6 ng/g creatinine) and increased significantly during pregnancy (1st trimester 230 +/- 50 ng/g creatinine; 3rd trimester 522 +/- 53 ng/g creatinine). Urinary 2,3-dinorthromboxane B2 showed no gender differences and no directed change was observed during pregnancy. In neonates urinary 2,3-dinorthromboxane B2 (6.328 +/- 1.210 ng/g creatinine) was high in their 3rd day of life and decreased rapidly thereafter. This pattern paralleled the behavior of 6-ketoprostaglandin F1 alpha. In young male smokers and non-smokers excretion of 2,3-dinor-6-ketoprostaglandin F1 alpha was not significantly different, whereas urinary 2,3-dinorthromboxane B2 was elevated in smokers (609 +/- 61 versus 351 +/- 41 ng/g creatinine, P less than 0.001). Values are mean +/- S.E.

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Using two new immunoradiometric assays for thyrotropin, we measured thyrotropin levels in serum of patients suffering from various clinically and biochemically diagnosed thyroid disorders, and in healthy controls. A thyroliberin stimulation test was performed in all patients and controls. Thyrotropin levels were measured using a solid phase IRMA in 339 patients and a coated tube sandwich assay in 152 patients. The lower limits of detection of 0.1 mU/1 (solid phase IRMA) and 0.02 mU/1 (coated tube sandwich assay) as well as the specificity of these two assays were superior to those of conventional thyrotropin assays. Basal thyrotropin values were clearly different between euthyroid controls and patients non responding to thyroliberin stimulation. However, the values for these two groups overlapped those for patients showing a subnormal increase upon stimulation with thyroliberin. The thyroliberin stimulation test in patients with autonomous adenomas, together with the measurement of thyrotropin using these sensitive assays, provides additional information in the low range below 1.0 mU/1,i.e. below the lower limit of detection of conventional double antibody radioimmunoassays.

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To measure the concentrations of thyrotropin (thyroid-stimulating hormone), we used the components of a commercially available two-step "sandwich" enzyme immunoassay (Enzymun-Test TSH, Boehringer Mannheim) based on the specific binding of the beta-subunit of thyrotropin by monoclonal antibodies coated on polystyrene tubes. By modifying the original assay protocol, we lowered the limit of detection to 0.18 milli-int. units/L, using a total incubation period of 22 h. With this modification we could differentiate between patients responsive to administration of thyroliberin (thyrotropin-releasing factor) and those who were non-responders, by measuring only the basal concentration of thyrotropin. Furthermore, we demonstrated a correlation between the basal concentration of thyrotropin and its increase after administration of thyroliberin (r = 0.77, n = 48).

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Isolation of the corticosteroid-binding globulin CBG was achieved by 5 chromatographical steps on cortisol Sepharose, QAE-Sephadex A-50, Con A-Sepharose and hydroxylapatite. The purity of the isolated CBG was demonstrated in polyacrylamide gel electrophoresis, SDS electrophoresis, immunodiffusion and ultracentrifugation. Microheterogeneity was shown in isoelectric focusing by 5 bands in the pH range of 3.7--4.2, which could be reduced to one major band after neuraminidase treatment. The equimolar binding of cortisol to CBG was demonstrated by binding studies. The association constant for cortisol was 2.8 x 10(8)M-1, for progesterone 1.7 x 10(6)M-1. From analytical ultracentrifugation, the molecular weight was calculated on 50 700; the sedimentation coefficient was 3.6 S, the partial specific volume 0.690 ml/g, the Stokes radius 38 A and the frictional coefficient ratio 1.5. A specific radioimmunoassay for CBG was established using the purified CBG for immunization, radioiodination and for calibration standards. The normal range of CBG levels in human serum was 2.4--4.4 mg/100 ml (mean +/- 2 SD). Studies were performed to compare the levels of CBG and thyroxine-binding globulin (TBG). No sex differences but a significant biphasic age dependence were observed for both proteins. In pregnancy and under oestrogen treatment of women and men, CBG was demonstrated to be the more distinct indicator of oestrogenic activity as compared with TBG, whereas the sensitivity of TBG was more pronounced to supposedly antioestrogenic substances like Danazol, and in severe disease. No coincidence of genetic CBG and TBG deficiencies have been found so far.

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