Biomedical subjects

K Rootwelt

Publications and source records attributed to K Rootwelt.

At least 19 recordsLinked to original sources

PubMed1992

A comparison of regional cerebral blood flow and middle cerebral artery blood flow velocities: simultaneous measurements in healthy subjects.

Blood flow velocities were measured in both middle cerebral arteries (MCAs) of 36 healthy subjects using transcranial Doppler ultrasound. Measurements were first made using a hand-held probe. Velocities were then studied bilaterally with fixed probes under resting conditions and during simultaneous regional CBF (rCBF) measurements. A significant (p < 0.05) positive correlation was found between MCA flow velocities and rCBF in the estimated perfusion territory of this artery. The correlation coefficient was highest when the measurements were performed simultaneously (p < 0.001) or when velocities recorded with a hand-held probe were adjusted to take into account the significant velocity increase induced by the CBF study situation. The increased velocities during CBF measurements cannot be fully explained by the moderate but significant PCO2 increase. Other possible mechanisms are increased blood flow due to mental activation or MCA vasoconstriction secondary to stimulation of the sympathetic nervous system. The effect of mental activation and PCO2 differences should therefore be considered when comparing the results of repeated velocity and CBF measurements.

Adult↗

PubMed1992

Regional cerebral blood flow after long-term exposure to carbon disulfide.

Sixteen former rayon viscose workers were investigated four years after the exposure to carbon disulfide was discontinued. Median age was 58 years (range 43-65 years), median exposure time was 17 years (range 10-35 years). Encephalopathy was diagnosed in altogether 14 workers. To further explore pathophysiological mechanisms, cerebrovascular investigations were employed. Doppler ultrasound examination of the precerebral vessels in 15 workers showed a slight stenosis of the left internal carotid artery in one. Regional cerebral blood flow investigation (rCBF) with single photon emission computerized tomography (SPECT) with Xenon-133 gas was performed in 14. There was no significant difference from a control group. Regional side-to-side asymmetries beyond reference limits were demonstrated in eight workers. The abnormalities were modest, but may indicate a tendency toward focal blood flow disturbances in workers with long-term exposure to carbon disulfide.

Adult↗

PubMed1992

Cerebral blood flow findings in moyamoya disease in adults.

Three adult patients with moyamoya disease are described. They presented with intracerebral hematoma, cerebral infarction and subarachnoid hemorrhage, respectively. Subarachnoid hemorrhage is rare in moyamoya and is usually the result of aneurysm rupture. No aneurysm was found in our patient. Regional cerebral blood flow (rCBF) and the cerebral perfusion reserve assessed by the acetazolamide test, were significantly reduced in all three patients. The areas with most reduced baseline rCBF and most impaired vasoreactivity did not always correspond to the site of the vascular accident, indicating that these CBF changes were at least in part due to the moyamoya disease and/or its underlying causes, and not solely to the vascular accidents.

Adult↗

PubMed1992

Nitroprusside and regional vascular capacitance in patients with severe congestive heart failure.

BACKGROUND: This study investigates the effects of sodium nitroprusside on regional vascular capacitance in eight patients with severe congestive heart failure (New York Heart Association class IV) and pulmonary hypertension. METHODS AND RESULTS: Regional relative blood volumes in the splanchnic and pulmonary region were determined by equilibrium blood pool scintigraphy. Hepatic venous wedge pressure and the mean of pulmonary artery and pulmonary capillary wedge pressure were used to represent the distending pressures of the splanchnic and pulmonary capacitance vessels, respectively. The dose of sodium nitroprusside was increased stepwise until systolic pulmonary artery pressure decreased below 50 mm Hg. This caused reductions in mean aortic pressure from 89 +/- 5 to 66 +/- 3 mm Hg (p less than 0.005), in pulmonary capillary wedge pressure from 31 +/- 1 to 16 +/- 2 mm Hg (p less than 0.001), and in hepatic venous wedge pressure from 10.0 +/- 1.0 to 5.9 +/- 0.6 mm Hg (p less than 0.005). Intestinal blood volume increased by 26 +/- 7% (p less than 0.005), whereas hepatic blood volume decreased by 9 +/- 3% (p less than 0.02). Pulmonary blood volume was unchanged. Analysis of intestinal and pulmonary vascular pressure-volume relations showed larger or equal blood volumes contained at lower distending pressures, indicating that sodium nitroprusside reduced smooth muscle tone of the capacitance vessels in these regions. The reduction of hepatic blood volume was compatible with passive expulsion of blood subsequent to reduced venous pressure. There was no change in the count rate from the spleen. CONCLUSIONS: Nitroprusside reduced venous pressure in patients with congestive heart failure by active relaxation of intestinal and pulmonary capacitance vessels. Hepatic vascular volume was probably reduced by a passive mechanism.

Gated Blood-Pool Imaging↗

PubMed1992

A comparison of transcranial Doppler and cerebral blood flow studies to assess cerebral vasoreactivity.

BACKGROUND AND PURPOSE: The aim of this study was to determine the ability of transcranial Doppler ultrasonography when used to assess cerebral vasoreactivity. The results of this method were compared with regional cerebral blood flow measurements. METHODS: Forty-three patients with symptoms suggesting cerebrovascular disease took part. Transcranial Doppler findings in the middle cerebral arteries were compared with regional cerebral blood flow in the corresponding perfusion territories before and after acetazolamide administration. RESULTS: There was a significant positive correlation between the absolute increase in cerebral blood flow in milliliters per 100 g per minute and the percent increase in velocity (r = 0.63). The right-left, side-to-side difference of the acetazolamide response obtained by the two methods also showed a positive correlation (r = 0.80). Control limits obtained from healthy subjects were used for both the blood flow increase (absolute values and asymmetry in absolute values) and the velocity increase (percent increase and asymmetry in percent increase). The two methods then agreed in their evaluation of vasoreactivity in 74 (86%) of the 86 middle cerebral artery perfusion territories; 20 (23%) were assessed by both methods as having a reduced vasodilatory reserve. Eleven hemispheres with a slightly reduced regional cerebral blood flow response to acetazolamide were not detected by transcranial Doppler, whereas all territories with a marked reduction were identified by Doppler. Only one hemisphere with a normal cerebral blood flow increase after acetazolamide administration was assessed by Doppler as having reduced vasoreactivity. CONCLUSIONS: Transcranial Doppler and the acetazolamide test may be used in clinical situations to assess cerebral vasoreactivity.

Acetazolamide↗

PubMed1992

Iopentol in patients with chronic renal failure: its effects on renal function and its use as glomerular filtration rate parameter.

Iopentol (mean dose 0.42 g I kg-1) was administered for abdominal aortography and pelvic angiography in 10 patients with advanced non-diabetic chronic renal failure (S-creatinine 672 +/- 259 mumol l-1, mean +/- SD). Renal glomerular function measured as creatinine clearance and plasma clearance of [99Tcm]-diethyl-enetriaminepentaacetic acid (DTPA) was unchanged by iopentol, as also was urinary excretion of the renal tubular enzymes N-acetyl-beta-glucosaminidase (NAG) and alkaline phosphatase (ALP). The elimination of iopentol from serum and urine was delayed, and detectable serum and urine concentrations were found 5 days after administration of the contrast medium. Creatine clearance was 47% higher than the corresponding renal iopentol clearance. Plasma iopentol clearance, measured as the total area under the plasma concentration curve, was 40% higher than renal iopentol clearance because of extrarenal elimination of iopentol. We conclude that abdominal aortography with iopentol can be performed without effects on renal glomerular or tubular function parameters in patients with advanced renal failure. If iopentol is used for measurement of glomerular filtration rate (GFR) in this group of patients, one should measure renal clearance, as plasma clearance overestimates GFR.

Adult↗

PubMed1992

Single lung transplantation. Surgical experiences with the first seven patients.

Seven single lung transplants are reported. The patients were severely disabled and oxygen dependent below sixty years of age with a poor prognosis. Diagnosis were alfa 1-antitrypsin deficiency (3), sarcoidosis (3) and idiopathic emphysema (1). Multiorgan-harvesting including six hearts, was performed in local or distant hospitals (3). Partial cardiopulmonary bypass simplified transplantation. The surgical procedure was modified with a direct transpericardial approach. Soft tissue wrapping by a vascularized pedicle secured the bronchial anastomosis. The four drug immunosuppressive regimen included cyclosporin A, azathioprine, steroids and antithymocyte globulin. Primary graft function was excellent. Six patients survived the postoperative period and are alive 5-19 months post transplant. Transbronchial biopsies and lung function studies have been helpful in detecting pulmonary rejections. Patient rehabilitation is satisfactory in most patients with improvement in physiologic parameters.

Adult↗

PubMed1992

99mTc-hexamethylpropyleneamine oxime leukocyte scintigraphy and C-reactive protein levels in the differential diagnosis of brain abscesses.

The demonstration and accurate localization of intracerebral mass lesions are commonly performed with computerized tomography (CT), which often cannot determine the nature of the lesion. As an aid in the differential diagnosis between brain abscess and neoplasm, the authors have evaluated both 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) leukocyte scintigraphy and the serum C-reactive protein level. Of 23 patients with intracranial mass lesions, 22 individuals showed ring-like contrast enhancement on CT scans; the one exception was a patient treated for a meningioma who had a negative CT scan despite clinical suspicion of intra- or extracranial abscess. The final diagnosis was invariably established by microscopic examination of tissue specimens. In 10 patients the final diagnosis was brain abscess; the other 13 patients harbored a brain neoplasm (glioma in nine, astrocytoma in one, and metastasis in three). The 99mTc-HMPAO leukocyte scintigraphy detected all cases of abscess. There were no false-positive results. An elevated C-reactive protein level (> 13 mg/liter) was found in all but one patient with abscess and in three patients with neoplasm; two of these three patients had dental root infections which could account for the elevation of C-reactive protein. It is concluded that 99mTc-HMPAO leukocyte scintigraphy should be performed when there is a possibility that a brain abscess may exist. Any steroid treatment should be discontinued for 48 hours prior to leukocyte scintigraphy. Also, C-reactive protein determination should be performed and is useful even when steroids are given.

Adolescent↗

PubMed1991

[Shunt quantification in adults with atrial septal defects using the radionuclide technique].

Quantification of left to right shunt was carried out in 15 adult patients, mean age 49 years, with a suspected ostium secundum atrial septal defect (ASD II). Radionuclide shunt quantitation correlated well with the results of right heart catheterization (r = 0.85). The radionuclide technique failed in two patients for technical reasons, but revealed no false negative or false positive results when technically satisfactory. The diagnosis was confirmed at operation. It is concluded that the radionuclide technique is a useful and reliable method which can also be used at follow-up after surgery in patients with atrial septal defects of secundum type.

Adult↗

PubMed1991

[Nuclear medical methods in cardiology].

201-Thallium scintigraphy and radionuclide ventriculography with 99m-Technetium are the two most important nuclear imaging techniques in clinical cardiology. The sensitivity and specificity of tomographic Thallium scintigraphy for detection of coronary heart disease is about 90%. Radionuclide ventriculography may be used to describe systolic and diastolic function of the left and right ventricles with results comparable to those of angiographic studies. Both methods are non-invasive and feasible during exercise. These methods provide important information on myocardial ischaemia and cardiac function which may be difficult to obtain by other methods. In county hospitals with no equipment for invasive studies these methods provide important diagnostic and prognostic information. In the university hospitals, however, the techniques are of a more supportive nature and may help the clinician to select appropriate treatment.

Coronary Disease↗

PubMed1991

[Hypothyroidism. Emphasis on clinical aspects or laboratory tests? Report about well known facts which, however, can be doubted].

This article discusses the reliability of laboratory-based diagnosis of hypothyroidism by means of combined determination of TSH and FT4. Differential diagnoses and supplementary tests are listed, and administrative and analytical errors reviewed. It is concluded that unexpected results should not be accepted without undertaking control analyses and supplementary examinations. Partial selective peripheral resistance to thyroid hormones (persons who have normal TSH and FT4 but need thyroxine therapy) is a very uncommon condition. Patients suspected of this disorder should be referred to their respective regional hospitals, and the results of the study should be published in international journals.

Diagnosis, Differential↗

PubMed1991

A single plasma sample method for estimation of the glomerular filtration rate in infants and children using iohexol, II: Establishment of the optimal plasma sampling time and a comparison with the 99Tcm-DTPA method.

The glomerular filtration rate (GFR) can be determined from the plasma disappearance rate of the non-ionic contrast medium iohexol. A preceding study established the empirical formulae enabling the development of a single plasma sample method for estimation of GFR in infants and children. In the present study the validity of these empirical formulae was confirmed in examinations in 143 patients. The results of the single plasma sample method were similar to those of a standard 99Tcm-DTPA method, and also with those of a two plasma sample iohexol method. Evaluation of the results obtained with plasma sampling 1 h, 2 h, 3 h and 4 h after the injection of the contrast medium showed that the optimal sampling time was about 3 h after the injection.

Adolescent↗

PubMed1991

Effects of short-term treatment with naproxen on kidney function in insulin-dependent diabetic patients with microalbuminuria.

The renal effects of the prostaglandin synthesis inhibitor naproxen was investigated in eight patients with incipient type I diabetes nephropathy. The patients were treated with 1000 mg naproxen daily for 4 days in a placebo-controlled double-blind cross-over study. Naproxen reduced urinary prostaglandin E2 (PGE2) excretion by 60%, from 276 ng/24 h to 110 ng/24 h (P less than 0.05). Plasma renin activity (PRA) was reduced by 45% (P less than 0.05). Glomerular filtration (GFR) (single bolus 99mTc-DTPA technique) and effective renal plasma flow (ERPF) (131I-Hippuran clearance) were unchanged by naproxen. Microalbuminuria and renal albumin clearance was unchanged as was also urinary excretion of sodium, glandular kallikrein and beta 2-microglobulin (beta 2-M). Our results show that albumin excretion in incipient diabetic nephropathy is not solely dependent on the renal prostaglandin system. The difference in action between naproxen in this study and indomethacin in previous reports, could be caused by renal actions of indomethacin independent of the prostaglandin system.

Adult↗

PubMed1991

The clearance of iohexol as a measure of the glomerular filtration rate in children with chronic renal failure.

The plasma clearances of technetium-99m-labelled DTPA ([99Tcm]-DTPA) and the non-ionic contrast medium iohexol were estimated in 11 children with chronic renal failure for determination of the glomerular filtration rate (GFR). Equal values were obtained with the two substances provided plasma sampling was simultaneous, but when plasma was sampled within 3.5 h after injection of iohexol and [99Tcm]-DTPA the GFR was overestimated by more than 50%. For clearance values below 20 ml min-1 1.73 m-2, valid GFR estimates were obtained both from two plasma samples taken 3 h and 24 h after the injection of iohexol and from a single plasma sample taken 24 h after the injection.

Adolescent↗

PubMed1990

Carbon disulfide exposure and neurotoxic sequelae among viscose rayon workers.

In Norway's only viscose rayon plant, carbon disulfide (CS2) concentrations in ambient air usually were between 30 and 50 mg/m3 during the first 23 years of production. From 1970/1971 until the factory was closed in 1982, corresponding values were 10-25 mg/m3. Through all of these years, high peak exposures of CS2 and H2S occurred. In 1986, 16 of the 24 men still at work in 1982 and with at least 10 years' experience in the spinning room agreed to participate in this study. Clinical neurological examination demonstrated abnormalities in 15; neuropsychological tests showed impairments of probable organic origin in 14. Thirteen had cerebral atrophy demonstrated by cerebral computed tomography (CT). Electromyography (EMG) was abnormal in six, neurography in 11. Regional cerebral blood flow measurements indicated flow asymmetries in eight, whereas Doppler investigation of the extracranial carotid and vertebral arteries, electroencephalography (EEG), and evoked response investigations were mostly normal. Based on these results and the exposure data, a diagnosis of CS2-induced encephalopathy was reached in eight workers; another six had an encephalopathy in which CS2 exposure was regarded as a partial cause. Correspondingly, seven had a neuropathy probably caused by CS2 exposure alone; in three others, CS2 was found to be the partial cause of a neuropathy. This indicates that long-term, relatively moderate exposure to CS2 in association with high peak exposures to CS2 and H2S involves a substantial risk of developing neurotoxic disease.

Adult↗

PubMed1990

Cluster headache: transcranial Doppler ultrasound and rCBF studies.

Transcranial Doppler and rCBF examinations were carried out in 25 cluster headache patients. Spontaneous and glyceryl trinitrate (nitroglycerin) provoked attacks were accompanied by a bilateral decrease in middle cerebral artery blood flow velocities. This decrease was more pronounced on the symptomatic side but the difference did not reach statistical significance. Mean hemispheric blood flow and rCBF were within normal limits during provoked attacks and similar to those found when patients were attack-free. During cluster periods middle cerebral artery velocities were significantly higher on the symptomatic side. Glyceryl trinitrate caused a bilateral middle cerebral artery velocity decrease which was significantly greater on the symptomatic side. Attacks provoked by glyceryl trinitrate appeared to begin when the vasodilatory effect of this substance was receding.

Adult↗

PubMed1990

Glomerular filtration rate estimated by X-ray fluorescence technique in children: comparison between the plasma disappearance of 99Tcm-DTPA and iohexol after urography.

The total plasma disappearance of the non-ionic contrast medium iohexol was determined by X-ray fluorescence technique following intravenous urography in 10 children aged between 2 and 13 years. For comparison the plasma disappearance of 99Tcm-DTPA was estimated both 2 days before and simultaneously with the iohexol study. High correlations between the three sets of data were found and no change in the glomerular filtration rate was detected following injection of contrast medium. It was also found that reliable estimates of the glomerular filtration rate can be obtained from two plasma samples of 1 ml each, taken 3 h and 4 h after the injection of the contrast medium.

Adolescent↗

PubMed1990

Acetazolamide effect on cerebellar blood flow in crossed cerebral-cerebellar diaschisis.

We studied the effect of acetazolamide on cerebellar blood flow in 11 stroke patients with large, unilateral cerebral hemispheric infarcts and no evidence of cerebellar infarction, but with cerebrocerebellar diaschisis of cerebral blood flow. Blood flow was determined with xenon-133 inhalation and dynamic single-photon emission computed tomography at rest and 20 minutes after the intravenous injection of 1.0 g acetazolamide. After acetazolamide, the mean +/- SD increases in blood flow in the affected and contralateral cerebellar hemispheres were 11.1 +/- 3.7 and 12.0 +/- 5.3 ml/100 g/min, respectively; the difference between hemispheres was not significant. The absolute increase in cerebellar flow in these 11 patients was of the same magnitude as that in 12 healthy controls. We conclude that cerebellar vasoreactivity is intact in stroke patients with crossed cerebrocerebellar diaschisis of cerebral blood flow. Our results lend further support to the concept that reduced cerebellar blood flow is secondary to functional deactivation. Our patients were studied 2 weeks to 5 years after their stroke, indicating that this phenomenon may be persistent.

Acetazolamide↗