Search PubMed⌕ Search

Biomedical subjects

V Unger

Publications and source records attributed to V Unger.

At least 19 recordsLinked to original sources
PubMed1997

[A new method of ex vivo whole blood perfusion of isolated mammalian organs, exemplified by the kidney of swine].

A new method for the ex vivo perfusion of organs from large mammals is described. Gas exchange and dialysis are carried out simultaneously with a low-flux polysulfon dialysis module. The dialysate (e.g. Tyrode solution) is aerated with a mixture of oxygen and carbon dioxide to ensure gas exchange with the blood. Dialysis is carried out in a closed thermostatically controlled system. Monitoring of ultrafiltration is maintained by continuously weighing the blood reservoir and adjusting an afferent and efferent blood pump. Initial results obtained with isolated pig kidneys demonstrate the suitability of the new method for use as a model for the replacement of animal experiments. Theoretically, clinical application in the area of in vivo regional organ perfusion may also be possible.

Animals↗
PubMed1993

Extracellular volume expansion inhibits antidiuretic hormone increase during positive end-expiratory pressure in conscious dogs.

1. This study in conscious dogs examined the effects of extracellular volume expansion on plasma antidiuretic hormone, atrial natriuretic peptide and aldosterone concentrations, plasma renin activity, and haemodynamic and renal responses during controlled mechanical ventilation with 20 cmH2O positive end-expiratory pressure. 2. Twenty experiments (10 controls, 10 expansion experiments with 0.5 ml min-1 kg-1 body weight of a balanced electrolyte solution given intravenously throughout) were performed in five trained, conscious, tracheotomized dogs over 4 h: first and fourth hour, spontaneous breathing; second and third hour, 20 cmH2O positive end-expiratory pressure. 3. In the control experiments positive end-expiratory pressure increased plasma antidiuretic hormone concentration from 1.4 +/- 0.2 to 10.0 +/- 3.3 pg/ml, plasma aldosterone concentration from 113 +/- 19 to 258 +/- 58 pg/ml and heart rate from 77 +/- 5 to 94 +/- 5 beats/min. Positive end-expiratory pressure did not change plasma atrial natriuretic peptide concentration (55 +/- 5 pg/ml), plasma renin activity (2.6 +/- 0.4 pmol of angiotensin I h-1 ml-1) and mean arterial pressure 103 +/- 3 mmHg). 4. In the expansion experiments, positive end-expiratory pressure did not change plasma antidiuretic hormone concentration (1.1 +/- 0.1 pg/ml), plasma aldosterone concentration (25 +/- 2 pg/ml), plasma atrial natriuretic peptide concentration (82 +/- 8 pg/ml), plasma renin activity (0.8 +/- 0.15 pmol of angiotensin I h-1 ml-1), heart rate (92 +/- 6 beats/min) and mean arterial pressure (111 +/- 4 mmHg). 5. In the control experiments, urine volume, sodium excretion and fractional sodium excretion remained in a low range during positive end-expiratory pressure, whereas potassium excretion increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1993

Inferior vena caval pressure increase contributes to sodium and water retention during PEEP in awake dogs.

UNLABELLED: This study compared the hemodynamic, renal, and hormonal effects of an experimentally induced increase in inferior vena caval pressure (IVCP) [to the same extent as during controlled mechanical ventilation (CMV) with positive end-expiratory pressure (PEEP)] with those of CMV with PEEP. Six volume-expanded conscious chronically tracheotomized dogs were studied under three conditions: CONTROL: 4 h of spontaneous breathing at 4 cmH2O continuous positive airway pressure (CPAP); CMV: CPAP for the 1st and 4th h and CMV with PEEP for the 2nd and 3rd h, resulting in a mean airway pressure of 20 cmH2O; and Increased IVCP: 4 h of CPAP, with IVCP increased during the 2nd and 3rd h by inflation of a chronically implanted cuff. Urine volume, sodium excretion, and fractional sodium excretion decreased during the 2nd and 3rd h of CMV and during increased IVCP compared with CONTROL. Glomerular filtration rate, mean arterial pressure, and antidiuretic hormone, atrial natriuretic peptide, and aldosterone plasma concentrations were not affected by CMV or Increased IVCP. Plasma renin activity decreased during CONTROL and Increased IVCP conditions but remained elevated during the 2nd and 3rd h of CMV. We conclude that, in conscious extracellular volume-expanded dogs, IVCP elevation contributes considerably to the water- and sodium-retaining effect of short-term CMV with PEEP.

Anesthesia↗
PubMed1992

[Pneumoperitoneum in a premature, non-ventilated neonate with respiratory distress syndrome leading to respiratory failure. What is the etiology?].

The authors describe the finding of extensive tensive pneumoperitoneum which developed during distension therapy (CNP) in an immature neonate. The absence of another extraalveolar cumulation of air made the authors use PO2 analysis in the peritoneal air by means of a transcutaneous electrode. Because the PO2 rose after connection of the electrode to the catheter draining the abdominal cavity, the authors assumed a respiratory aetiology of the pneumoperitoneum and did not consider laparatomy. They assume that the above test may be valuable in the differential diagnosis between respiratory and gastrointestinal pneumoperitoneum in those instances where it is not possible to assess the aetiology of pneumoperitoneum unequivocally.

Humans↗
PubMed1991

[Urethral dilation in the treatment of urinary tract infections in girls].

In the presented retrospective study the authors evaluate the effect of dilatation of the urethra in the treatment of relapsing infections of the urinary pathways in girls. In 1982-1987 at the Clinic of Paediatric Surgery in Brno 387 girls with infections of the urinary pathways were examined, in 112 stenosis of the distal urethra was found, in 24 moreover vesicoureteral reflux and 40 suffered from enuresis. After dilatation of the urethra, the technique of which is described in detail the urinary findings were normal in 83% of the girls and in more than half significant or complete regression of the vesicoureteral reflux was noted, in more than two thirds enuresis was eliminated. The authors therefore recommend the method and also calibration of the urethra during examination of the patients.

Adolescent↗
PubMed1989

[Evaluation of the value of testicular phlebography].

The authors use testicular phlebography since 1979; they examined so far 72 patients (62 children and 10 adults). Phlebography was indicated in 54 patients with varicocele and in 18 children with an unpalpable testicle. The authors evaluate the method with regard to the surgical procedure in the treatment of varicocele. In unpalpable testicles phlebography proves in some cases useful in the differential diagnosis. The authors evaluate the importance of the examination. The new findings regarding anatomical and functional aspects are, no doubt, valuable. On the other hand, the authors draw attention to the complicated examination (in particular in children) to the invasive character of the examination and the irradiation load.

Adolescent↗
PubMed1982

[Functional effect of the argon laser on the hearing organ of the guinea pig].

While numerous histological findings point towards a possible destruction of inner-ear structures by the Argon-Laser we still miss a satisfactory statement concerning functional impact of stapedectomy or stapedotomy using laser beams. To investigate this we irradiated the promontorium of each of 10 guinea-pigs with laser powers between 0.6 W and 2.2 W ten times for 0.5 s. Then, and on the first, fifth and tenth postoperative day we recorded the brainstem potential evoked by bone-conducted clicks. We found that after the application of laser power up to 1.2 W a reversible threshold shift of up to 20 dB took place. Above powers of 1.2 W a permanent threshold shift was found (Fig. 1). Before sacrificing the animals we recorded the course of temperature in the perilymph during laser irradiation (Fig. 2 and 3). In order to set application limits of power within we consider laser impact functionally critical we compared the temperature increment during single shots and permanent elevation of the temperature above body temperature with values we have found earlier at the human petrous bone (Fig. 2 and 3). This led us to the conclusion that the temperature increment during the shot might be the limiting factor as far as the deterioration of inner-ear function is concerned. This may very well coincide with our hypothesis (Thoma and coworkers, 1981) that the vaporization of endocochlear fluid during the shot is a possible cause of cochlear malfunction after stapedectomy by laser.

Animals↗
PubMed1981

Left atrial distension and intrarenal blood flow distribution in conscious dogs.

Measurements were made with radioactive microspheres of the distribution of renal blood flow in conscious dogs during left atrial distension. Urine volume, sodium excretion, mean arterial blood pressure and heart rate increased during the 60 min period of left atrial distension (increase in left atrial pressure by about 1.0 kPa). Total renal blood flow and cardiac output (electromagnetic flowmeters) did not change. The perfusion rates of four renal zones did not change. Striated muscle blood flow (M. psoas) fell markedly.--Stimulation of left atrial receptors in conscious dogs is followed by an increase in renal and skeletal muscle resistance. The diuresis and natriuresis during left atrial distension is not accompanied by a detectable redistribution of renal cortical blood flow.

Animals↗
PubMed1981

[Measurement of temperature and sound pressure in the inner ear during application of the argon-laser (author's transl)].

Laser stapedectomy is looked upon as an operation method which may be less harmful to the inner ear. The purpose of this study was to investigate the course of temperature behind the footplate of isolated human petrous bones while using the Argon Laser. We found that a non-linear relationship exists between the power of the Laser beam, the duration of the impulse and the sudden temperature rise during the impulse. Another, though linear, relationship exists between the energy of the beam and the permanent elevation of temperature in the perilymph during repeated shots. The observation of tiny bubbles beneath the focus on the wall of a plastic tube (which we used as a model for flow studies) led us to assume that the same may be true for the perilymph, too. The bursting of these bubbles was thought to cause a sudden rise of pressure in the inner ear. We were able to measure this Laser-generated sound pressure which reached 59 dB (A) for a beam energy of 1.0 Ws. Very low frequencies, which were not determined by this method, might very well cause damage to the inner ear structures. Finally, we proved that the results found a the isolated petrous bone which we fixed in a 37 degree waterbath can be transferred to in vito conditions: The course of the temperature was investigated in the cochlea of live Guinea pigs and shortly after death without detecting any change of the results.

Animals↗
PubMed1980

[Chronobiological aspects of artificial total heart replacement in long-term animal experiments--a systemanalytic study (author's transl)].

Biological rhythms (circadian rhythms) have been observed in the hemodynamics of experimental animals (calves). After artificial total heart replacement these rhythms are typically altered compared to control animals. These observations induce a growing consideration of chronobiological aspects in a systemanalysis for the conception of an automatic external control of the artificial heart, which has to be divided in:--parameter-progression (tendencies), --parameter-variation (discrete, oscillations), --parameter-coupling (phase shifts).

Animals↗
PubMed1979

Hemodynamics during hemodialysis, sequential ultrafiltration and hemofiltration.

Circulatory parameters were determined by cardiac catheterization in patients on maintenance hemodialysis. They were studied in three groups during conventional hemodialysis, sequential ultrafiltration and hemofiltration. All three groups revealed significant reduction of cardiac output, stroke volume, pulmonary artery pressure and plasma volume. In the hemodialysis group hemodynamic parameters were unstable; specifically, hypotension, increased heart rate, and only minimal increase of peripheral resistance were observed. The other two groups showed only minor changes in circulatory parameters despite high ultrafiltration rates. Blood pressure and heart rate remained stable. On the other hand, peripheral vascular resistance increased remarkably. There is compelling evidence that during hemofiltration and sequential ultrafiltration, the patient's ability for vasoconstrictive counterregulation is better maintained than during conventional hemodialysis.

Blood Pressure↗
PubMed1978

[Stable postoperative phase after total artificial heart-replacement in animal-experiments (author's transl)].

Presented are results of an analysis of more than 30000 data which were sampled in seven long-surviving calves after total artificial heart-replacement (more than 35 days survival). The continuity of 24 types of data (hemodynamic, labor- and physical data) are transformed for every animal in time-equidistant datafields and after this an average continuity for all seven animals is calculated and plotted. Twenty days after the operation the data have reached the preoperative values in nearly all cases, indicating a stable phase starting, according to the clinical condition of the animals.

Animals↗
PubMed1978

Hemodynamic studies, acid-base status and osmolality in different hemodialysis procedures.

Three patients on maintenance dialysis were each treated with three different procedures: A) twenty-liter recirculation dialysis with bicarbonate buffering, B) recirculation-adsorption dialysis and C) single-pass dialysis. Hemodynamic parameters were measured invasively and procedures A, B and C were compared for each patient. In this intraindividual comparative study, the authors attempted to establish a relationship between the varying hemodynamic parameters and the changes in osmolality and acid-base status. There were indications of some causal relationship to circulatory stability: in A and B, there were peripheral resistance increases of 24.5% and 38.4%, respectively, with stable circulation; in C, there was a 6.1% increase and unstable circulation. Additionally, the influence of acidosis is shown in B, with disproportionately strong reductions of cardiac output (21.9%) and pulmonary artery pressure (44.9%); In spite of a decrease of osmolality (A: 15.6 mOsm/L), stable circulation could be achieved if the peripheral resistance was substantially increased and acid-base status was equalized.

Acid-Base Equilibrium↗