PubMed Health⌕ Search

Biomedical subjects

U Finsterer

Publications and source records attributed to U Finsterer.

At least 55 records · Page 3Linked to original sources
PubMed1992

A framework for the knowledge-based interpretation of laboratory data in intensive care units using deductive database technology.

In co-operation with the Institute of Anaesthesiology of the Ludwig-Maximilians-University in Munich a computer-based system for the analysis and interpretation of renal function, fluid and electrolyte metabolism of critical care patients has been developed. This paper focuses on the requirements and implementation aspects of the knowledge-based interpretation for this particular system. Objective of the proposed approach is, to transform an enormous--and constantly increasing--amount of raw data available in modern intensive care units (ICUs) into relevant, patient-oriented information, which is easy to understand by the medical staff. The essential features of a knowledge-based system at an ICU are outlined. A system is described where these features are realized using deductive database technology as a specification paradigm and extended relational databases as an implementation platform. The integration into the hospital information system is highlighted.

Artificial Intelligence↗
PubMed1992

Visualization of large datasets in intensive care.

At the "Institut für Anaesthesiologie der Ludwig-Maximilians-Universität" in Munich a computer-based system for the analysis and interpretation of renal function and fluid and electrolyte metabolism of critical care patients has been developed. This paper describes requirements and implementation aspects of the presentation of data to the physician. Key issue is, how to transform the enormous--and, as we all know, constantly increasing--amount of plain data available in modern intensive care units (ICUs) into relevant information which can be easily turned into therapeutic actions. These issues have been discussed in literature extensively over many years, but with the upcoming of moderately priced, though powerful graphical UNIX workstations an extended functionality is feasible.

Artificial Intelligence↗
PubMed1992

[The determination of plasma volume using indocyanine green in man].

The importance of circulating blood (BV) and plasma volume (PV) in critically ill patients and physiological research is unchallenged. Recently, Evans blue (EB) [8, 25] and radioactively labelled serum albumin (RIHSA) [20] have mostly been used as tracers for PV determination. However, the disadvantages of radioactive contamination (RIHSA) and dye accumulation (EB), especially in repeated measurements, are obvious. In addition, recent reports show a possible carcinogenic potential for EB [15, 21]. This has prompted us to examine the feasibility of indocyanine green (ICG), a tricarbocyanine dye currently used for cardiac output and liver blood flow measurements, for the determination of PV. The volume of distribution of ICG has been reported to represent PV [5, 26]. METHODS. In 23 healthy volunteers (19 men and 4 women), PV was determined in duplicate (PV1, PV2) with an interval of 30 min. Before injection a tourniquet was put around the arm and a pressure above the systolic arterial pressure was applied for 2 min. During recirculation, ICG (2.5 mg/ml) was administered in a dose of 0.25 mg/kg as a bolus injection over 5 s via an antecubital vein. Blood was drawn from an antecubital vein of the contralateral arm at 1 min intervals. After centrifugation, the optical density (corrected for blank) was read in a densitometer. Third- to ninth-minute plasma samples were used to calculate monoexponential plasma decay curves. The ICG concentration at injection time was achieved by extrapolation. A calibration curve was generated using 5 different known ICG concentrations. PV was calculated from injected ICG dose divided by ICG concentration at injection time. BV and red cell volumes (EV) were derived from measured PV and hematocrit (hct). RESULTS. Between minutes 3 and 9, tracer decay was monoexponential in all but 1 subject. From minute 10 on the plasma decay of ICG represented another, slower compartment (Fig. 1). The plasma half-life of ICG was 3.2 +/- 0.6 min (mean +/- SD). Mean PVs per body weight and body surface area (BSA) were 44 +/- 5 ml/kg and 1662 +/- 176 ml/m2, respectively. Linear regression revealed PV2 = 0.92.PV1 + 226 (r = 0.92) (Fig. 2). The mean percentage of difference (D) was -0.6%, the methodologic error (SD) +/- 5.7% [27]. Linear regression of PV and BSA revealed PV = 1885.BSA -416 (r = 0.71, P less than 0.0001) (Fig. 3). BV and EV estimates (Table 2) obtained from PV and hct showed reproducibility in the range of the PV determination because of excellent reproducibility of hct measurements. DISCUSSION. ICG plasma half-life times in our experiments were comparable to those reported by other authors [18, 19, 24]. Reproducibility of PV determination was good and was well within the limits of other tracer methods (EB, RIHSA) [17, 27]. Using exclusively peripheral veins for ICG injection and blood withdrawal did not seem to affect the accuracy of PV determination. PV estimates obtained by the ICG method showed good agreement with those known from the literature [7, 10, 25]. Our results correspond especially well with the data reported by Hurley [14] obtained from 481 healthy men using different methods (Evans blue, RIHSA, or labelled red cells).

Adult↗
PubMed1991

[Intra-arterial catheter oximetry and pulse oximetry in comparison with CO-oximetry in heart surgery].

This study evaluates the measurement of oxygen saturation by arterial catheter oximetry and pulse oximetry. The values are compared to values obtained by CO-oximetry. METHODS. In eight patients undergoing cardiac surgery, we determined the oxygen saturation of arterial and mixed-venous blood by CO-oximetry (IL 282, Instrumentation Lab) at prospectively defined points of measurement before, during, and after extracorporeal circulation. At the same points of measurement, saturation readings obtained by arterial catheter oximetry (U425C, Abbott) and pulse oximetry (Siemens/Nellcor) were recorded. RESULTS. The mean saturation values determined by both catheter oximetry and pulse oximetry differed from the mean values obtained by CO-oximetry by less than 1% (= bias). The standard deviations of the readings in relation to readings of CO-oximetry (= precision) were +/- 0.5% to +/- 1.0% for catheter oximetry and +/- 1.0% to +/- 1.3% for pulse oximetry. Furthermore, it was possible to obtain saturation readings in 99%-100% of measurements by catheter oximetry; in contrast, this was possible by pulse oximetry in only 59%-84% of measurements. Low mixed-venous saturation values were not indicated by any of the arterial methods of measurement. CONCLUSIONS. Catheter oximetry was superior to pulse oximetry with regard to both precision of saturation values and reliability to obtain values. Invasiveness and high costs are disadvantages of catheter oximetry, but if reliable and exact measurements are important at any time during surgery or intensive therapy, intra-arterial catheter oximetry is preferable to pulse oximetry.

Cardiac Surgical Procedures↗
PubMed1988

[The equilibrium of nitrogen, potassium and phosphate and renal excretion of creatinine and creatinine over the course of 3 weeks following severe trauma].

In 19 patients after accidental trauma and with intact renal function during an observation time of 21 days we found a cumulated negative balance of nitrogen (N), phosphate (P) and potassium (K) amounting to a mean of 214g, 357 and 447 mmol, respectively. Median daily potassium balance was positive on day 2 to 5 and this was interpreted as an increased extrarenal potassium deposition due to increased levels of circulating catecholamines. Median renal creatinine excretion was about 120% of predicted normal till day 10 and continuously decreased thereafter to values lower than predicted normal. Three patients did not show creatinuria (greater than 200 mg/day) during the whole observation time. In 15 patients after a "free interval" with a mean duration of 7 days creatinuria frequently developed rather quickly and maximal excretion of creatine was as high as 4 g/day. In 7 patients creatinuria persisted to the end of the 21 days observation time. During the phase of creatinuria the median cumulated excretion of creatine amounted to 14.4 g. The "free interval" of creatinuria after severe trauma is remarkable. Most of the N, K and P, which is lost from the body during this time obviously stems from tissues other than sceletal muscle. During the phase of creatinuria, however, the negative balance of N, K and P seems to be mainly due to muscle wasting. Hypophosphatemia was prominent during the first 5 days after trauma and obviously was caused by a decrease in renal phosphate threshold (TmPO4/GFR). The underlying mechanism of this primary change in renal function after severe trauma could not yet be identified.

Adolescent↗
PubMed1988

[Water-electrolyte balance and kidney function for 3 weeks following severe trauma].

A study on water-electrolyte metabolism and renal function was performed in 32 patients (mainly young to middle-aged males) over three weeks after severe accidental trauma (mainly brain trauma), who did not suffer from acute renal failure. With a mean water input of 4 l/day the difference of water input and urine volume was positive over the whole observation time. Patients had a mean osmolar excretion of 1800 mosm/day which was twice normal and was mainly caused by a high urea excretion. They were almost invariably in the state of antidiuresis and achieved unusually high values for negative free-water clearance around 2 ml/min. This, however, was adequate in terms of normotonicity of body water. Cumulated sodium balance over 21 days was negative and, on the average, amounted to minus 440 mmol. The median value for creatinine clearance was in the range of predicted normal (156 ml/min.) between day 5 and 10 and a little less before and thereafter. We frequently observed an elevation of creatinine clearance to 120-150% of normal. Renal clearance of urea was around 100 ml/min. during the phase of maximal protein catabolism. Therefore the reasonable increases in urea production up to a mean of 60 g/day resulted only in moderately elevated levels of plasma urea (40-50 mg/100 ml). In 14 patients we performed a total of 83 measurements of plasma volume (Evans-Blue). In patients with intact renal function mean plasma volume amounted to 110% normal. This, in combination with a reduced red all volume on the average, resulted in mild hypovolaemia (blood volume about 90% of predicted normal).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1986

[Thiopental levels in the plasma during induction of anesthesia].

The thiopentone sodium surge in plasma was investigated in 15 elderly surgical patients and 10 young adults during injection, over a period of 1 minute, of 4 mg of anaesthetic per kg of fat-free body weight (in 18 patients), and 5 mg per kg of fat-free body weight (7 patients). In keeping with prolonged circulation time in old age, thiopentone sodium reached the sampling site faster in the younger patients than it did in the older patients. In the majority of cases, thiopentone sodium concentrations in plasma reached a maximum of between 60 and 80 micrograms/ml. Mean thiopentone sodium concentrations in the older patients were 10% higher, but here values differed so widely that this result must be regarded as coincidental. It was, accordingly, impossible to establish any statistically verifiable differences between young and old patients by estimating the volume of thiopentone sodium distribution shortly after the end of injection. Plasma protein binding, 85% on average, with extremes ranging from 79% to 89% did not depend on thiopentone concentration or age. In the group of patients studied, it was not possible to confirm statistically that the plasma protein concentration influenced the rate of binding. Dosage according to fat-free body weight did not diminish inter-individual differences in plasma concentration-time profiles.

Adult↗
PubMed1986

[Renal effects of dopamine in healthy adults with special reference to the excretion of phosphate and calcium].

The intravenous application of 4 micrograms/kg/min dopamine (DA) over 3 h in 11 healthy volunteers resulted in an increase in inulin clearance and urine volume by about 10%, renal excretion of sodium and calcium being increased by DA by a factor of 5. We found a strong linear correlation between changes of renal excretion of sodium and calcium under DA (r = 0,90). The concentration of ionized calcium in whole blood was absolutely stable under DA in the range of 1.25 to 1.27 mmol/l. The application of the catecholamine also resulted in a significant reduction of plasma volume by a mean of about 10% and in a nonsignificant reduction of intravascular protein mass by 8%. The phosphaturic effect of DA was weak and unpredictable. We suppose that in the intact organism the pharmacologic effect of dopamine on the tubular handling of phosphate which seems to be experimentally proven, may be masked by other mechanisms with an antiphosphaturic action such as increased levels of growth hormone and/or insulin.

Adult↗
PubMed1983

Total and ionized calcium levels during open heart surgery with two different pump priming solutions.

UNLABELLED: Changes of total (Ca) and ionized Ca-levels (Ca2+) were studied during open heart surgery in 18 patients. 9 patients (group A) had only crystalloid solutions as pump priming, the other 9 patients (group B) had 500 ml of citrated whole blood in the priming solution. For assessment of hemodilution hct and total plasma protein and plasma albumin were determined. Measurements were done preoperatively, before and after systemic heparinisation, during and after extracorporeal circulation (ECC) and on the first postoperative day. RESULTS: 1. Anticoagulation with 375 U/kg BW heparin had no effect on ionized calcium levels. 2. With onset of ECC (Ca) decreased by 30% in group A and by 20% in group B. (Ca2+), however, decreased by 20% in group A and by 35% in group B. The percentage of ionized calcium increased by 15% in group A whereas it decreased by the same amount in group B. This difference is contributed to the calcium binding effect of citrate added to pump priming in group B. Mechanisms of the relative increase of ionized calcium during ECC in group A, however, remain to be studied.

Blood Glucose↗
PubMed1983

Metabolism of phosphate and calcium after severe accidental trauma.

Hypophosphatemia is a common finding during the first 4-5 days after severe accidental trauma. We demonstrated that hypophosphatemia after trauma is caused by a definite decrease in renal phosphate threshold (TmPO4/GFR), that is the theoretical plasma phosphate concentration at which all of the filtered phosphate is reabsorbed by the renal tubules and renal excretion of phosphate is close to zero. We speculated that the decrease in renal phosphate threshold could be due to an increased activity of PTH which in turn could be the result of ionized hypocalcemia. In 7 patients with severe and in 8 patients with moderate trauma, however, we found ionized calcium and PTH levels to be within normal limits. Total plasma calcium was below normal (1.90-2.00 mmol/l) up to 20 days after trauma, probably due to a decreased plasma albumin concentration (25-30 g/l). We conclude, that ionized hypocalcemia and consecutive stimulation of PTH is not the cause of decreased renal phosphate threshold after severe accidental trauma.

Adolescent↗
PubMed1982

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH)--treatment with lithium.

Two patients with SIADH after brain trauma are described. Features of SIADH are "inappropriate" antidiuresis and excessive natriuresis with negative sodium balance resulting in hyponatremia and plasma hypoosmolality which may lead to cerebral dysfunction. Oral lithium carbonate was beneficial in both patients. With plasma levels of lithium around 1 mmol/l a temporary impairment of renal concentrating ability and antinatriuresis with normalization of plasma sodium and plasma osmolality was observed. The SIADH subsided about 4 months after the original trauma, long after gross neurological symptoms had resolved.

Accidents, Traffic↗
PubMed1981

[Relationship of haematocrit and plasma protein concentration pre- and postoperatively under "isotonic" haemodilution and haemoconcentration, and during laparatomy (author's transl)].

An increase or a decrease in blood volume caused by adding or subtracting isotonic but protein-free fluid to or from whole blood theoretically will result in disproportionate percentage changes of haematocrit and plasma protein concentration. Percentage changes of plasma protein concentration are larger than those of haematocrit and depend upon the initial haematocrit. It could be demonstrated that the theoretical rules of "isotonic" haemodilution and haemoconcentration do hold in vivo in patients pre- and postoperatively under isotonic volume expansion and furosemide diuresis, respectively. However, during laparotomy with moderate blood loss and infusion of crystalloids only we observed a definite decrease of intravascular protein mass. This seemed to be only partly due to surgical blood loss. We suppose that during laparotomy considerable amounts of intravascular protein, besides those with surgical blood loss, are lost in the area of the wound and into the peritoneal cavity.

Blood Proteins↗
PubMed1981

[Changes in plasma volume during and after middle-ear procedures (author's transl)].

We observed 20 patients undergoing middle-ear surgery under NLA in combination with halothane for controlled hypotension in respect to haematocrit, plasma protein concentration, plasma volume (Evans Blue) and intravascular protein mass during and after anaesthesia and surgery. As surgical bleeding was almost nil and infusion therapy was not necessary, patients behaved as a "closed system". With the start of anaesthesia we found a significant decrease of haematocrit and plasma protein concentration, being complete after 45-60 min, and unchanged thereafter until the end of anaesthesia. Suspicion of an increase in plasma volume could not yet be verified by a measurement of this parameter after 30 min of anaesthesia. Just after termination of anaesthesia we observed a significant increase in haematocrit and plasma protein concentration compared to control values with a downward trend over the next hour. At that point we also measured a decrease in plasma volume by 10% and in plasma protein mass by 6% compared to controls. These findings are interpreted as part of an "arousal reaction" with a temporary disequilibrium between transcapillary filtration rate of water and proteins and back transport of these substances via lymph flow.

Blood Proteins↗
PubMed1981

[Changes in plasma zinc under anesthesia and surgery (author's transl)].

Postoperative hypozincemia is a common finding and may be interpreted as ACTH-induced dissociation of zinc from the albumin fraction in plasma. Due to the high protein-bound fraction of zinc in plasma rapidly developing hypozincemia may be caused by dilution of plasma proteins. This may be roughly checked by dividing plasma zinc concentration by plasma protein concentration. By this means we observed that in middle ear surgery and in laparotomies under NLA during anesthesia and surgery there is no evidence for dissociation of zinc from plasma proteins. This probably stress-induced phenomenon was, however, already seen in the first postoperative hour after laparotomies. During anesthesia and surgery we observed a profound increase in renal zinc excretion, the cause of which in unknown.

Anesthesia↗
PubMed1981

[Electrolyte balance in major abdominal surgery. IV. Water diuresis under anesthesia and surgery (author's transl)].

12 patients with major laparotomies were studied during anesthesia alone, during three hours of surgery and during the first two hours of recovery. We demonstrated a decrease in plasma potassium and plasma sodium concentration starting with anesthesia and development of a moderate metabolic acidosis. Plasma osmolality was stable during anesthesia and surgery, but slightly decreased in the early postoperative period. Urine formation and osmolar clearance as well as renal sodium and potassium excretion showed a rising tendency during operation, reaching their maximal values in the recovery room. Sodium balance was positive during and after surgery, and sodium retention amounted to about 75% of sodium infused. Urine-to-plasma-osmolality-ratio was 2,0 under anesthesia alone, decreased during surgery and reached control values in the recovery room. In 5 out of 12 patient studied we demonstrated a temporary water diuresis at different points of anesthesia and laparotomy and occasionally even in the postoperative period. This could be due to low plasma levels of ADH caused by relative hypervolemia in the absence of other stimuli of ADH-secretion.

Acidosis↗
PubMed1980

[Electrolyte balance in major abdominal surgery. III. On insensible water losses from the peritoneal cavity (author's transl)].

Two groups of 16 patients each were studied during abdomino-surgical procedures. Patients of one group received an isotonic glucose solution to cover insensible water losses from the peritoneal cavity whilst patients of the other group were not treated with glucose. In these we found a significant increase in plasma osmolality and in mean corpuscular hemoglobin concentration of the red cells during anaesthesia and operation. The balance of osmotic free water was calculated from changes of plasma osmolality during the observation period. Calculating output as difference between known input and balance we found losses of osmotic free water amounting to approximately 4.5 ml per kilogram bodyweight per hour of operation in both groups. These losses are, in our opinion, identical with the insensible water loss from the peritoneum. Plasma sodium concentration in both groups showed decreasing tendency compared with plasma osmolality. This was partly due to dilution with increased extracellular glucose concentration and partly to an extra-intracellular shift of sodium (without net-water-flux). Plasma potassium concentration decreased in patients receiving glucose but increased in patients without glucose. Red cell potassium concentration decreased in both groups. Urin-to-plasma ratio of osmolality was equal in both groups in spite of a different water balance. Patients receiving glucose had higher urine outputs and therefore (with equal osmolar U/P ratio) a higher osmolar clearance and a higher free-water-reabsorption. It is demonstrated that under conditions as described the amount of free-water reabsorption and concomitantly a favourable effect on water balance during mild dehydration is mainly depending on osmolar clearance.

Abdomen↗