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Biomedical subjects

D Krauss

Publications and source records attributed to D Krauss.

At least 19 recordsLinked to original sources
PubMed2001

Differential transesophageal echocardiographic diagnosis between linear artifacts and intraluminal flap of aortic dissection or disruption.

BACKGROUND: The relatively low specificity of transesophageal echocardiography (TEE) for the diagnosis of aortic dissection (AD) or traumatic disruption of the aorta (TDA) has been attributed to linear artifacts. We sought to determine the incidence of intra-aortic linear artifacts in a cohort of patients with suspected AD or TDA, to establish the differential TEE diagnostic criteria between these artifacts and true aortic flaps, and to evaluate their impact on TEE diagnostic accuracy. METHODS AND RESULTS: During an 8-year period, patients at high risk of AD (n = 261) or TDA (n = 90) who underwent a TEE study and had confirmed final diagnoses were studied. In an initial retrospective series, linear artifacts were observed within the ascending and descending aorta in 59 of 230 patients (26%) and 17 of 230 patients (7%), respectively. TEE findings associated with linear artifacts in the ascending aorta were as follows: displacement parallel to aortic walls; similar blood flow velocities on both sides; angle with the aortic wall > 85 degrees; and thickness > 2.5 mm. Diagnostic criteria of reverberant images in the descending aorta were as follows: displacement parallel to aortic walls, overimposition of blood flow, and similar blood flow velocities on both sides of the image. In a subsequent prospective series (n = 121), systematic use of these diagnostic criteria resulted in improved TEE specificity for the identification of true intra-aortic flaps. CONCLUSIONS: Misleading intra-aortic linear artifacts are frequently observed in patients undergoing a TEE study for suspected AD or TDA. Routine use of the herein-proposed diagnostic criteria promises to further improve TEE diagnostic accuracy in the setting of severely ill patients with potential need for prompt surgery.

Adolescent↗
PubMed2000

[Hyperbaric oxygen therapy in retinal artery occlusion].

UNLABELLED: Retinal artery occlusion (RAO) is an ophthalmological emergency that causes a major decrease of visual parameters in most of the cases. Purpose of this pilot study was to evaluate the effect of adjunctive hyperbaric oxygen therapy (HBO) on visual acuity (VA). PATIENTS AND METHODS: Patients with acute central or branch artery occlusion (CRAO/BRAO) consecutively admitted to our hospital were offered adjunctive HBO. Standard therapy consisted of ocular massage for 3 minutes, paracentesis and intravenous acetazolamide. HBO (3 x 30 minutes at 240 kPa) was applied t.i.d. on the first day, b.i.d. on day 2 and 3 and o.d. for at least another 4 days. Patients who refused HBO or had contraindications served as controls. VA was measured according to the guidelines of ETDRS. The follow up was 3 months. RESULTS: HBO: 8 patients with CRAO showed a mean increase in VA of 1 line, 4 of 8 patients had an increase of 2 lines and more, in 3 of 8 patients VA was unchanged and one patient suffered a decrease of 6 lines. 10 patients with BRAO showed a mean increase in VA of 8 lines, 8 of 10 patients showed an mean increase of 2 and more lines, in 2 of 10 patients VA was unchanged. CONTROLS: 8 Patients with CRAO had a mean increase of 2 lines during follow up, 3 of 8 patients showed an increase of 2 lines and more, in 5 of 8 patients VA was unchanged. 6 patients with BRAO had a mean increase of VA of 4 lines, 3 of 6 patients had an increase of 2 lines and more, one patient lost 3 lines and in 2 patients VA was unchanged. The results are compared to the literature. CONCLUSIONS: HBO seems to be beneficial for VA in eyes with BRAO. Further investigations are necessary to prove this observation.

Acetazolamide↗
PubMed1997

Cardiovascular complications of malignant carcinoid disease.

Carcinoid tumors are endocrinologic malignancies often associated with a characteristic syndrome-the malignant carcinoid syndrome. Cardiovascular manifestations of this rare illness result from unique pathophysiologic characteristics, are associated with poor prognosis, and are difficult to treat medically. The hemodynamic consequences of this disease present unique management problems perioperatively. New pharmacologic and surgical therapies for malignant carcinoids have improved quality of life for patients to the extent that carcinoid heart disease now has more impact on morbidity and mortality rates. Cardiologists may be called on to diagnose and treat this rare cardiac disease. We review, for consulting cardiologists, the pathophysiologic characteristics, cardiovascular manifestations, and management of this disease.

Cardiovascular Diseases↗
PubMed1997

Comparative effects of losartan and enalapril on exercise capacity and clinical status in patients with heart failure. The Losartan Pilot Exercise Study Investigators.

OBJECTIVES: This study was designed to determine 1) whether 12-week oral administration of losartan, an angiotensin II receptor antagonist, in patients with heart failure is well tolerated; and 2) whether functional capacity and clinical status of patients with heart failure in whom treatment with an angiotensin-converting enzyme (ACE) inhibitor is replaced with losartan for 12 weeks will remain similar to that noted in patients in whom treatment with an ACE inhibitor is continued. BACKGROUND: Losartan is a specific, nonpeptide angiotensin II receptor antagonist. Although specific receptor blockade with losartan has certain theoretic advantages over nonspecific ACE inhibition, definitive demonstration of comparable effects in patients with congestive heart failure is lacking. METHODS: A double-blind, multicenter, randomized, parallel, enalapril-controlled study was conducted in 116 patients with congestive heart failure (New York Heart Association functional classes II to IV) and left ventricular ejection fraction < or = 45% previously treated with stable doses of ACE inhibitors and diuretic agents, with or without concurrent digitalis and other vasodilators. After a baseline exercise period, open-label ACE inhibitors were discontinued, and patients were randomly assigned to 12 weeks of therapy with losartan, 25 mg/day (n = 38); losartan, 50 mg/day (n = 40); or enalapril, 20 mg/day (n = 38). Drug efficacy was evaluated by changes in maximal treadmill exercise time (using a modified Naughton protocol), 6-min walk test, left ventricular ejection fraction and dyspnea-fatigue index. Safety was measured by the incidence of clinical and laboratory adverse experiences. RESULTS: The treadmill exercise time and the 6-min walk test did not change significantly after replacement of ACE inhibitor therapy with losartan. Similarly, a significant change was not observed in either the dyspnea-fatigue index or left ventricular ejection fraction at the end of double-blind period relative to baseline. CONCLUSIONS: Losartan was generally well tolerated and comparable to enalapril in terms of exercise tolerance in this short-term (12-week) study of patients with heart failure. The clinical effects of long-term angiotensin II receptor blockade compared with ACE inhibition remain to be studied.

Activities of Daily Living↗
PubMed1997

Transnasal transesophageal echocardiography.

Transesophageal echocardiography has been used as a diagnostic tool in the critical care unit. However, long-term serial evaluation of ventricular function with transesophageal echocardiography is difficult because of the current probe sizes and intolerance to prolonged oral intubation. We performed 139 intubations (64 oral and 75 transnasal) with a new prototype probe in 128 patients referred for transesophageal echocardiography. Transnasal intubation with the prototype probe was possible in 63/75 attempts. Oral intubation was successful in all 64 attempts. Patients tolerated transnasal intubation well when mildly sedated or awake. Two-dimensional echocardiographic views obtained with the nasal probe were similar to those obtained with a standard monoplane probe. Image quality was rated as good or acceptable in nearly all cases. Transgastric short-axis imaging of the left ventricle combined with acoustic quantification provided stable left ventricular area waveforms. Using custom developed software we showed the feasibility of monitoring left ventricular performance with minimal probe adjustment while graphically displaying and updating left ventricular area and fractional area change. Thus, transesophageal echocardiography with a prototype miniaturized monoplane probe passed transnasally is feasible, safe, and well tolerated by patients. This probe provides excellent two-dimensional echocardiographic images and may allow long-term echocardiographic monitoring of ventricular performance.

Adult↗
PubMed1994

Does a mid-lumbar block level provide adequate anaesthesia for transurethral prostatectomy?

In this prospective, randomized study, 23 patients having spinal anaesthesia for transurethral prostatectomy (TURP) were evaluated for the adequacy of their block using a visual analog pain score (VAPS). Each patient with a "standard" (> or = T10) block level (n = 5) or "intermediate" (L1 or T12) block level (n = 5) found the block adequate. Sixty-two percent (8/13) of patients with a "low" (< or = L3) block level found their block adequate. The VAPS was assessed every five minutes or whenever pain abruptly increased during TURP; an "inadequate block" was defined as a VAPS > or = 5/10 during prostatic resection. Intravesical pressure was monitored and kept < 15 mmHg to distinguish between pain from bladder distension and from prostatic resection. "Low" block patients (LBP) who found their block inadequate (n = 5) received supplemental intrathecal local anaesthetic given through a spinal catheter. The subsequent L1 block level was adequate for TURP. In LBP, who found their block adequate (n = 8), a higher (P < 0.01) VAPS was observed than in patients with a "standard" block level. However, a smaller (P < 0.05) maximum percent decrease in diastolic blood pressure was found in LBPs, than in "intermediate" or "standard" block patients. It is concluded that a spinal block > or = L1 is adequate during TURP when bladder pressure is monitored and kept low. Mid-lumbar block levels should be reserved for patients in whom the benefit of minimizing haemodynamic changes outweighs the risk of a "less complete" anaesthetic.

Aged↗
PubMed1994

Paradoxic improvement in regional wall motion during high-dose dobutamine stress echocardiography. A marker for hibernating myocardium?

Dobutamine stress echocardiography detects myocardial ischemia by inducing regional left ventricular systolic dysfunction. Augmentation of wall motion in hypokinetic segments has also been noted with low-dose dobutamine, suggesting myocardial viability. We report a case of regional ventricular improvement during high-dose dobutamine therapy, which may represent relief from myocardial hibernation or changes in regional loading conditions.

Aged↗
PubMed1991

Use of gadolinium-enhanced MR imaging for differentiating mucoceles from neoplasms in the paranasal sinuses.

The purpose of this study was to determine whether additional clinically useful information could be obtained from gadolinium-enhanced magnetic resonance (MR) imaging compared with the information obtained from nonenhanced MR imaging and computed tomography (CT). Therefore, the authors selected 41 patients, whose results at CT examinations demonstrated a variety of pathologic conditions of the paranasal sinuses, to undergo MR imaging both with and without the use of gadopentetate dimeglumine for contrast enhancement. In 22 of 35 cases of neoplasms and mucoceles occurring separately, the lesions were correctly differentiated by established MR signal criteria alone. However, 32 of these 35 cases were accurately differentiated when gadolinium-enhanced MR images were obtained. Six cases demonstrated co-existing neoplasm and mucocele: Gadolinium-enhanced MR enabled correct differentiation of five of these lesions, while unenhanced MR enabled correct differentiation of three. On the basis of these results, the authors conclude that the use of gadopentetate dimeglumine for contrast enhancement at MR imaging is useful for differentiating mucoceles from neoplasms in the sinonasal tract.

Contrast Media↗
PubMed1991

Cardiac tamponade and contralateral hemothorax after subclavian vein catheterization.

A patient developed life-threatening cardiac tamponade and contralateral hemothorax after insertion of a subclavian catheter in the operating room. Contrast was infused through the catheter, demonstrating its malposition in the pericardial space. Contrast infusion was valuable in evaluating this complication of central line placement.

Cardiac Tamponade↗
PubMed1991

Influence of environmental temperature on growth, muscle and adipose tissue metabolism, and meat quality in swine.

An experiment involving 32 individually housed, castrated male pigs was conducted to determine the effects of environmental temperature (12 degrees C = T12 or 28 degrees C = T28) on the performance, carcass characteristics, muscle and adipose tissue metabolism, and meat quality of pigs fed to achieve equal rates of weight gain between 8 and 92 kg live weight. The T12 pigs had less muscle (P less than .01) and more subcutaneous fat (P less than .01) in the ham than did T28 animals. Thyroids and adrenals were heavier (P less than .01) in T12 than in T28 pigs. Percentage of type I muscle fibers was higher (P less than .01) and fiber cross-sectional areas smaller (P less than .01) in semispinalis muscle (SS) of T12 pigs, whereas no effect of temperature was noticed in longissimus muscle (LD). Cold exposure induced a larger increase in oxidative metabolism in SS (+30 to 32%, P less than .001) than in LD (+14 to 17%, P less than .10) and an enhanced glycolytic metabolism in LD (P less than .05). Lipid concentration was higher in SS of T12 than in that of T28 pigs. Lipogenic enzyme activities and unsaturation of backfat were higher in T12 than in T28 pigs, whereas no effect of temperature was noticed in leaf fat. Cold treatment resulted in a faster postmortem pH decline (P less than .01), higher glycolytic potential (P less than .01), and lower ultimate pH (P less than .01) in LD. The results indicate that 12 degrees C vs 28 degrees C induced detrimental effects on growth, ham composition, and muscle and adipose tissue quality.

Adenosine Triphosphatases↗
PubMed1990

Comparative enantioselective pharmacokinetic studies of celiprolol in healthy volunteers and patients with impaired renal function.

The pharmacokinetics of the beta 1-selective adrenergic antagonist (R,S)-celiprolol has been studied after oral administration of 200 mg celiprolol-HCl to 8 healthy volunteers and 8 patients with various degrees of impaired renal function. No significant difference was found between the two enantiomers in the control group or in the patients. In healthy volunteers an average of 9.8% of the dose of R-(+)-celiprolol and 9.5% of S-(-)-celiprolol was recovered unchanged in the urine. Renal impairment reduced the urinary excretion of both enantiomers to the same extent according to the severity of the uraemia, producing higher AUCs. Nevertheless, the terminal half-lives of the R- and S-enantiomers were not significantly different between the groups. Dosage reduction in patients with renal impairment does not seem to be necessary.

Administration, Oral↗
PubMed1989

Simultaneous determination of (R)- and (S)-celiprolol in human plasma and urine: high-performance liquid chromatographic assay on a chiral stationary phase with fluorimetric detection.

The quantitative enantiospecific determination of the beta 1-selective adrenergic antagonist (R,S)-celiprolol in human plasma and urine is described. It involves a two-step liquid-liquid extraction of celiprolol from biological material and separation of the underivatized enantiomers by high-performance liquid chromatography on a chiral stationary phase (cellulose tris-3,5-dimethylphenyl carbamate, coated on silica gel) with fluorimetric detection. R-(+)-Propranolol was used as an internal standard. The detection limits of 1.5 ng/ml enantiomer in plasma and 2.5 ng/ml enantiomer in urine at signal-to-noise ratios higher than 3 permit the performance of pharmacokinetic studies after therapeutic doses.

Adrenergic beta-Antagonists↗
PubMed1989

Fluorimetric determination of norfloxacin in plasma and urine samples after thin-layer chromatographic separation.

A thin-layer chromatographic (TLC) assay for the determination of norfloxacin (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (piperazinyl)-3-quinolinecarboxylic acid), a new antibacterial agent, in human plasma and urine is described. Norfloxacin was extracted from plasma samples using commercial cartridges, urine samples were simply diluted with methanol. Plasma extracts or urine samples were applied to TLC plates (silica gel). Chromatography was performed with a mobile phase consisting of methanol, ethanol and water, the atmosphere in the tank being saturated with ammonia. The fluorescence intensity of norfloxacin was enhanced by dipping the plate into a paraffin/citric acid mixture. Peaks were quantified by fluorimetric measurement (excitation 313 nm/emission 390 nm, cut-off filter). The method showed acceptable precision and linearity in the range of 0.01 to 4 micrograms/ml for plasma and 1 to 100 micrograms/ml for urine. The assay was shown to be applicable to human plasma and urine samples.

Chromatography, High Pressure Liquid↗
PubMed1988

Enantiospecific high-performance liquid chromatographic (HPLC) determination of baclofen and its fluoro analogue in biological material.

A method is described for the quantification of baclofen enantiomers in biological material (urine, plasma, and cerebrospinal fluid). The samples were extracted by liquid-solid extraction using Sep-Pak C18 cartridges. The subsequent derivatization procedure contained two separate steps. (1) The butyl esters of the enantiomers were formed using butanolic hydrochloric acid (followed by ion-pair extraction of the intermediate products). (2) A chiral derivatization was then performed using S-(+)-naproxen chloride as reagent. S-(+)-Benoxaprofen chloride can also be used. The diastereomeric amides were separated by high-performance liquid chromatography (HPLC) on a silica gel column (mobile phase, n-hexane/dichloromethane/ethanol; detection, fluorescence measurement at 335/365 nm). The described procedure was also used for the quantification of the fluoro analogue of baclofen. Urinary excretion of baclofen enantiomers was investigated in two healthy volunteers after p.o. administration.

Amides↗
PubMed1988

Quantification of baclofen and its fluoro analogue in plasma and urine after fluorescent derivatisation with benoxaprofen chloride and thin-layer chromatographic separation.

An assay method for the quantification of the centrally acting muscle relaxant baclofen in human plasma and urine is described. Baclofen is separated from biological samples using Sep-Pak C18-cartridges. The liquid-solid extraction is followed by ion-pair extraction. The following procedure involves the formation of the baclofen butyl ester and an additional ion-pair extraction of the ester. Then a fluorescent derivatisation is performed, using the fluorescence marker benoxaprofen chloride. The resulting amide is separated from interfering compounds by TLC (silica gel) and quantified by directly measuring the fluorescence (313 nm/365 nm). The procedure described can also be applied for the determination of the fluoro analogue of baclofen. The lower limit of detection is 10 ng per 1 ml plasma and 20 ng per 0.1 ml urine. The applicability of the method was proved by investigating plasma and urine samples of 2 volunteers after oral administration of 20 mg baclofen as single dose.

Baclofen↗