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Biomedical subjects

R Knopp

Publications and source records attributed to R Knopp.

At least 55 records · Page 3Linked to original sources
PubMed1985

Blood volume distribution in the Trendelenburg position.

The Trendelenburg position is used frequently in treating hypotensive patients. It is believed that placing patients in the Trendelenburg position causes an autotransfusion of blood to the central circulation. No published studies document the volume of blood displaced centrally. In our study ten volunteers were placed in the Trendelenburg position. Blood volumes were determined from body surface area, and radionuclide scanning was used to determine blood volume distribution. Placing normovolemic volunteers in the Trendelenburg resulted in a 1.8% (median) displacement of the total volume centrally. The autotransfusion of blood produced by the Trendelenburg position is small and is unlikely to have an important clinical effect.

Adult↗
PubMed1985

Captopril mediated decrease of aortic regurgitation.

The effect of captopril mediated afterload reduction on aortic regurgitation was investigated in 10 patients. Regurgitation was quantitated by means of the regurgitation fraction and the relation of regurgitant volume to end diastolic volume. These variables were derived from gated radionuclide ventriculography. After captopril treatment the blood concentration of angiotensin I rose whereas that of angiotensin II fell significantly. The conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the regurgitant volume, normalised to end diastolic volume, were significantly reduced by captopril treatment. The ejection fraction remained essentially unchanged. These findings suggest that captopril reduces aortic regurgitation by reducing afterload.

Angiotensin I↗
PubMed1985

[Localization of pre-excitation in the WPW syndrome by analysis of the ventricular contraction course].

Fourier phase analysis of gated radionuclide ventriculography (RNV) was applied in 23 patient for the identification of cardiac contraction patterns in WPW syndrome (controls with normal ventricular function and sinus rhythm, n = 30). The sequence and velocity of regional ventricular wall motion was determined and correlated to the results of electrophysiological studies. In 3/23 patients the contraction pattern was not different from controls. Indicating the preexcitation in 20/23 patients the earliest ventricular contraction was localized as follows: right atrial n = 5, paraseptal right n = 2, paraseptal left n = 6 and atrial left n = 7. In 15/16 patients nuclear data corresponded with electrophysiological endocardial mapping. Phase analysis of RNV provides a reliable non-invasive method for localization of preexcitation in WPW syndrome.

Electrocardiography↗
PubMed1984

The use of gated radionuclide angiography in the diagnosis of cardiac contusion.

No currently used diagnostic test is an accurate predictor of patients who will develop morbidity or mortality from cardiac contusion. In a prospective study we used gated cardiac radionuclide angiography to assess cardiac function in 30 patients with blunt chest trauma, and we compared the results of this test with those of other diagnostic studies for cardiac contusion to determine whether gated angiography is a more accurate predictor of serious cardiac injury. Diagnostic tests included the following: serial electrocardiograms (ECG), serial creatine phosphokinase muscle-brain isoenzyme (CPK-MB) and lactic dehydrogenase (LDH) isoenzymes, gated cardiac radionuclide angiography, and technetium-99m (Tc-99m) pyrophosphate scintigraphy. Abnormal studies were present in 26 patients; 22 showed abnormalities in CPK-MB, 19 on ECG, and five on gated scan. No patient demonstrated an abnormal Tc-99m pyrophosphate scan or abnormal elevation of LDH isoenzyme. Although no diagnostic test was predictive of morbidity and mortality, CPK-MB isoenzyme was the only test to correlate with morbidity and mortality. Morbidity and mortality correlated most closely with the number of associated major injuries and the presence of hypotension or hypoxia.

Adolescent↗
PubMed1984

[Reduction of regurgitation in aortic insufficiency by inhibition of the renin-angiotensin converting enzyme].

The effect of captopril-mediated afterload reduction on regurgitation was investigated in 10 patients with aortic insufficiency. Regurgitation was quantitated by the regurgitation fraction and the relation of regurgitant volume to enddiastolic volume, which were derived from gated radionuclide ventriculography. 19 patients with coronary artery disease and no evidence of valvular heart disease served as controls. In patients with coronary artery disease no significant regurgitation was found. In patients with aortic regurgitation the blood concentration of angiotensin I increased whereas that of angiotensin II decreased significantly after captopril-medication; thus, the conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the normalized regurgitant volume were significantly reduced. The ejection fraction remained essentially unchanged. These findings suggest a favorable influence of captopril-induced afterload reduction on hemodynamics in aortic regurgitation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1984

[Cause of crossed cerebellar diaschisis in cerebrovascular disease].

In 31 patients with completed stroke (n = 30) or PRIND (n = 1) a brain SPECT with 123I-labeled amphetamines was performed. In 14 (= 45%) of the respective patients--suffering from long-lasting hemiplegia--crossed cerebellar diaschisis was present. The interval between onset of the disease and time of examination varied between 1 week and 7 years. On the other hand, patients without crossed cerebellar diaschisis did not, with one exception, suffer from hemiplegia. It is likely that this phenomenon is caused by the reduction of spino-cerebellar stimuli due to the paresis of the respective extremities.

Adult↗
PubMed1984

Cardiac metabolism of 15 (p-I-123 phenyl-) pentadecanoic acid after intracoronary tracer application.

Myocardial turnover of omega-(p123I-Phenyl-) pentadecanoic acid and release of its metabolites into the coronary sinus and peripheral blood has been studied in patients with coronary artery and valvular heart disease. After intracoronary tracer injection myocardial extraction fractions of 45-53% in control subjects were observed. In patients with coronary artery disease (CAD) normal to reduced values (34-61%) were established. Hydrophilic catabolites of I-PPA, probably p123I-benzoic and -hippuric acid as well as small amounts of the non-metabolized tracer were found in coronary sinus and peripheral blood. Myocardial tracer uptake and clearance patterns were clearly different in normal myocardium when compared to that obtained in patients with CAD. Thus, evaluation of myocardial I-PPA metabolism might provide a new diagnostic tool for assessment of integrity of the heart's muscular metabolic function.

Coronary Disease↗
PubMed1983

Effect of estrogen/progestin potency on lipid/lipoprotein cholesterol.

We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women, using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P less than 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Enovid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives.

Adult↗
PubMed1983

Accuracy of standard radiographic views in detecting cervical spine fractures.

Recent studies have challenged the accuracy of standard radiographs for detecting cervical spine injuries. We used thin-section tomography to determine the accuracy of the cross-table lateral view (CTLV) alone, and the three standard emergency department views (CTLV, anteroposterior, and open-mouth) together, for detecting acute cervical spine fractures. Seventy-one patients with blunt cervical spine injuries had thin-section tomography performed for the following indications: fracture, dislocation, or suspicious findings on standard radiographs; or persistent severe pain or neurologic deficit. Tomography detected acute fractures in 44 of the 71 patients. The CTLV had a sensitivity of 82%, specificity of 70%, and accuracy of 77% for detecting patients with fractures. The three standard views had a corresponding sensitivity, specificity, and accuracy of 93%, 71%, and 84%, respectively. Eight patients with fractures had the CTLV interpreted as normal, and three patients with fractures had all three standard views interpreted as normal. The use of thin-section tomography is recommended when there are suspicious radiographic or clinical findings suggesting a severe cervical spine injury.

Cervical Vertebrae↗
PubMed1982

Single photon emission computed tomography of the lung: preliminary results.

Single photon emission computed tomography (SPECT) of the lung was performed, in addition to conventional camera scintigraphy, in 41 patients with pulmonary disorders as well as with regular pulmonary perfusion. For SPECT investigation a rotating gamma camera (Gammatome) was used consisting of a system with a high-resolution parallel-hole collimator interfaced with a digital computer. In 6 of 41 patients the diagnostic accuracy of pulmonary scintigraphy was improved by SPECT. Topographic identification of segmental perfusion defects in pulmonary embolism seems to be particularly promising. Special abnormalities that cannot be assessed by conventional lung imaging are mediastinal hernia and recessus retrotrachealis as a normal variant. For a detailed evaluation of this method a large number of patients must be investigated.

Humans↗
PubMed1982

Blood volume displacement with inflation of antishock trousers.

Eleven healthy male volunteers were studied to determine the amount of blood displaced by the inflation of the antishock trousers (AST) at pressures of 40 and 100 mm Hg. Radioisotope scans were used to determine the blood volume distribution and the change in the volume of distribution with inflation of the AST. The volunteers were then phlebotomized approximately one liter of blood and the study was repeated. Less than 5% of the total blood volume was displaced with inflation of the AST. It is unlikely that the clinical improvement seen with inflation of the AST in hypovolemic shock is due to autotransfusion of blood alone.

Adolescent↗
PubMed1982

Compartment syndrome after anti-shock trouser use without lower-extremity trauma.

The use of anti-shock trousers is widely advocated for the treatment of hypovolemic shock. Despite its frequent use, few complications have been reported in the medical literature. Although speculation exists that anti-shock trouser application may result in ischemic injury to the lower extremities, this complication has only recently been reported. Our report describes a patient with no lower extremity trauma who developed bilateral anterior and lateral compartment syndromes after the application of anti-shock trousers.

Adolescent↗
PubMed1982

Assessment of regional myocardial uptake and metabolism of omega-(p-123I-phenyl) pentadecanoic acid with serial single-photon emission tomography.

The utility of myocardial imaging and assessment of regional myocardial metabolism of omega-(123I-paraphenyl-)pentadecanoic acid (I-PPA) by means of serial single-photon tomography is demonstrated in animal experiments. High quality cross sectional images of dog hearts with clear delineation of left ventricular walls are obtained. Myocardial infarcts are visualized as areas of deficient radioactivity uptake. I-PPA elimination from non-infarcted myocardial regions is significantly (p less than 0.001) prolonged when compared with unaffected controls. Hence, not only localized absence of uptake of free fatty acid by infarcted myocardium can be demonstrated with serial single-photon tomography but also general impairment of cardiac FFA-metabolism.

Animals↗
PubMed1982

[SPECT (201T1) of the myocardium after experimental infarction].

On the basis of an experimental model the extent was studied to which even small intramural myocardial ischemia can be demonstrated by SPECT. For this purpose ligature of the Ramus interventricularis anterior (n = 10) or of the Ramus circumflexus (n = 2) of the left coronary artery was performed in 12 dogs to produce myocardial lesions of the anterior and posterior wall. Transmission computed tomography (TCAT) served as a control method in 10 dogs showing that 6 lesions were transmural and 4 intramural. All infarctions could be detected by SPECT with a rotating gamma camera (TCAT: 9/10). TCAT after contrast media enhancement with its morphological advantages (high resolution) should, however, not be used in the acute phase of myocardial infarction because of its hemodynamic side effects. Thus, SPECT with 201T1 remains the method of choice even for the proof of minor intramural (acute) ischemic lesions.

Animals↗
PubMed1981

Nasogastric tube displacement to the right as a sign of acute traumatic rupture of the thoracic aorta.

A study was undertaken to determine the accuracy of nasogastric tube (NGT) displacement to the right as a sign of acute traumatic rupture of the thoracic aorta (ATRTA). In 14 patients with confirmed ATRTA, the sensitivity of NGT displacement to the right was 70% using measurement of displacement from the midline on chest radiography. Two control groups, comprising victims of vehicular trauma and patients with no recent history of trauma, showed significant percentages of false positive findings for ATRTA based on NGT displacement. The presence of this radiographic sign is highly suspicious for this lethal injury; however, the absence of displacement cannot be used to exclude the diagnosis of ATRTA.

Adolescent↗
PubMed1981

The Parkmedic Program: prehospital care in the national parks.

The Parkmedic Program provides training and on-going supervision of national park rangers involved in advanced prehospital medical care in Yosemite, Kings Canyon, and Sequoia National Parks in California. This includes intravenous catheterization and drug administration in emergency situations. Course structure, experience to date, and recommendations for future programs are presented.

Adult↗