Search PubMed⌕ Search

Biomedical subjects

K Messmer

Publications and source records attributed to K Messmer.

At least 433 records · Page 24Linked to original sources
PubMed1980

[Regional blood flow in splanchnic organs during positive end-expiratory pressure ventilation (author's transl)].

An experimental study was performed on 10 dogs to evaluate the effect of positive end-expiratory pressure ventilation (PEEP) on hemodynamics and regional blood flow (RBF). The following conclusions can be drawn from the results of this study: 1) PEEP leads to a significant reduction of cardiac output (CO). 2) Total blood flow to the preportal splanchnic organs, and consequently the portal venous flow, decreases in proportion to the reduction of CO. Within the splanchnic area, there is a redistribution of RBF in favour of the small and large intestines, at the expense of stomach and pancreas. 3) The arterial blood flow to the liver is only moderately affected. 4) The observed changes of RBF may in part contribute to the complications of the splanchnic organs occurring in PEEP-ventilated patients. 5) PEEP should be used only when strictly indicated; close monitoring of organ function appears mandatory in these patients.

Animals↗
PubMed1979

MIC-II - a program for the determination of cardiac output, arterio-venous shunt and regional blood flow using the radioactive microsphere method.

MIC-II is a versatile BASIC computer program designed to calculate the cardiac output, the arterio-venous shunt and the regional blood flow from data obtained by the radioactive microsphere method. The samples are measured in a gammaspectrometer with a multichannel pulse height analyzer and the data are recorded on tape. Up to 10 different nuclides may be used simultaneously, including tracers which are not bound to microspheres. The nuclides may have overlapping energy spectra. The analysis of the energy spectra is performed according to the matrix method. Standard samples, each containing one pure nuclide, are measured to obtained the overlap matrix. The unkown amounts of the nuclides in the samples are obtained by solving a system of simultaneous linear equations. Up to 100 organ samples may be taken in one experiment. Up to 10 different organ maps, containing a text label for each organ specimen, may be created, edited, modified and stored on tape for convenient identification of input and output. Numerous validity checks for imput and output make MIC-II easy to use, even for non-computer trained personel.

Animals↗
PubMed1979

Tissue PO2 during reanimation with hemoglobin solutions.

Solutions of conventional stoma-free hemoglobin (SFH) and of pyridoxylated stoma-free hemoglobin (SFH-PLP) were compared in a dog model of reanimation from severe arterial blood loss. SFH and SFH-PLP restored central hemodynamics after infusion without yielding significant differences between the experimental groups. To cope with the developing hypovolemia, Ringer's lactate load amounted to about 120 ml/kg, edema formation was not encountered. Skeletal muscle oxygenation was studied by means of a multiwire platin electrode. The infusion of SFH-PLP was associated with a shift to the right of the cumulative PO2-distribution curve, indicating better tissue oxygenation. Oxygen was not unloaded from SFH in plasma unless the oxygen extraction from red cell hemoglobin exceeded 40%. Oxygen unloading was, however, improved when SFH-PLP with low oxygen affinity was used. Thus, SFH-PLP merits further consideration as a short-term oxygen-carrying blood substitute.

Animals↗
PubMed1979

[Tissue oxygenation during normovolemic hemodilution].

Limited hemodilution does not affect the respiratory function of the blood, neither in vitro nor in vivo. By virtue of the unchanged affinity of oxygen for hemoglobin and increase in nutritional flow, reduction in the O2 content of the blood is completely compensated. Tissue hypoxia does not develop as long as pulmonary and circulatory compensation is ensured. As a result, maintenance of a normal blood volume is an essential parameter. Information is not yet available concerning the relationship of O2 supplies in coronary disease. Coronary disease is presently considered to be a contra-indication since a marked reduction in the O2 content of the blood could restric coronary reserves and result in myocardial ischemia.

Animals↗
PubMed1979

[Hydroxyethyl starch (HAS 450/0.7) in human plasma and liver. Course of concentration and histological changes].

In 12 patients 1,000 ml hydroxyethyl starch (Mw 450,000, degree of substitution 0.7) was infused intravenously. A liver biopsy was performed in 10 patients undergoing abdominal surgery 30 minutes to 28 days after the infusion. The liver tissue was investigated by light and electron microscopy. The plasma level of hydroxyethyl starch decreased to 4.8% of the initial concentration 28 days after the infusion (Anthron method). Single intracellular vacuoles were shown by electron microscopy 30 minutes after the end of infusion in Kupffer's cells only. However, 6 to 28 days after infusion intracellular vacuoles were demonstrated in parenchymal liver cells, Kupffer's cells, interstitial histiocytes and to a lesser degree in the cells of the small bile ducts. The pathogenic importance of the portracted elimination from the plasma and the liver storage is unknown.

Adult↗
PubMed1979

[Prevention of thromboembolism by normovolemic hemodilution].

In general surgery, routine thromboprophylaxis is strongly recommended in order to reduce the risk of thrombo-embolic complications. If pre-operative hemodilution is used in order to avoid the risks of transfusions of homologous blood, dextran must be used as the diluent. Patients undergoing total hip replacement represent a very high risk group where infusion of dextran is superior to low doses of heparin, but pre-operative hemodilution using dextran is more effective than infusions of dextran. It may thus be concluded that pre-operative hemodilution with dextran would give similar improved results in general surgery. As with all thromboprophylactic agents, side-effects may occur. However, with dextran 60, anaphylactoid reactions have note been described up to the present time in patients undergoing hemodilution before operation.

Blood Coagulation↗
PubMed1978

[Hypothermic circulatory arrest after total blood exchange in dogs (author's transl)].

Total body washout (hct less than 1%) in hypothermia was performed in 31 dogs using either a crystalloidal or a colloidal perfusate. Blood exchange and cooling was achieved by means of partial bypass and heat exchanger. Short lasting blood exchange for crystalloids without cardiac arrest resulted in 66% survival of the animals. When in addition circulatory arrest was established for 30 min at 14 degrees C oesophageal temperature blood exchange for crystalloids was not tolerated. All four animals of this group died within 19 hours presenting massive interstitial edema. Replacement of the crystalloidal perfusate by a colloidal solution (2.5 g% Dextran 60 at Ringer's Lactate) and establishing circulatory for 30 or 60 min resulted in survival rates of 71% and 50% respectively. The use of the colloidal perfusate effectively prevented edema formation. Death could not be correlated with the parameters controlled.

Animals↗
PubMed1978

[Thrombosis prophylaxis with low doses of dextran 60 (author's transl)].

The antithrombotic effect of dextran 60 (Macrodex) was studied in a prospective, randomized trial on patients undergoing general surgery. 42 patients (group A) received 500 ml of dextran 60 intraoperatively, 49 patients (group B) received an additional dose of 100 ml dextran 60 on days 1 to 5 after operation. As tested by the 125-iodine-radiofibrinogen test 16 patients (38%) from group A, but only 2 patients (4%) from group B developed deep venous thrombosis. The difference between both groups is statistically highly significant (P less than 0,0005). The use of dextran for thromboprophylaxis was associated neither with hemorrhagic complications nor with anaphylactoid reactions. The fractionated application of a total of 1000 ml of dextran 60 resulted in a very efficient prophylaxis against deep venous thrombosis.

Aged↗
PubMed1978

Sodium nitroprusside-induced hypotension in dogs. Drug sensitivity and resistance experimentally provoked by circulating blood volume alterations.

The effects of small circulating blood volume alterations on the SNP dosage required to maintain the mean arterial pressure at 70 mm Hg were studied in 6 anesthetized dogs; (A) normovolemia, (B) hypovolemia by arterial bleeding 7 ml/kg, and (C) hypervolemia by infusing 7 ml/kg whole blood. The animals became extremely SNP sensitive during hypovolemia and resistant during hypervolemia (SNP dosage A: 25.8, B: 14.7, C: 70.0 microgram/kg/min); these changes were accompanied by significant changes in cardiac output (A: 193, B: 142, C: 249 ml/kg/min). The intravenous administration of SNP with the aim of inducing hypotension generally causes a balanced pre- and afterload reduction. This balance is rather delicate and easily disturbed by small intravascular fluid changes leading to cardiac output and thus to SNP sensitivity changes. Slowly developing tachyphylaxis can be explained on the basis of such intercompartimental fluid shifts and a case of SNP tachyphylaxis reported in literature is discussed on the basis of overinfusion. SNP tachyphylaxis or resistance might be treated by preload reducing measures like phlebotomy or the administration of nitroglycerin.

Animals↗
PubMed1978

[Organ blood flow in graduated, controlled hypotension induced with sodium nitroprusside].

Metabolic acidosis is a characteristic feature of SNP-induced hypotension; this acidosis is of hepatic origin and is not due to underperfusion of the organ but to cyanide-induced anaerobic metabolism. For SNP doses higher than 3 mg/kg body weight, lactate is produced in the myocardium, brain, and skeletal muscles. The observed changes were reversible after hypotension of 20 min duration.

Animals↗
PubMed1978

[Blood volume replacement and hemodilution with hydroxyethyl starch].

For high molecular hydroxyethylstarch (MW 450000, DS 0.7-0.8) an adequate volume effect has been demonstrated in numerous experimental and clinical studies; this colloid is, therefore, suitable for primary volume replacement as well as for preoperative normovolemic hemodilution. In contrast to colloids hitherto known HES infusion results in hyperamylasemia of probably non-pathogenic importance but significance for differential diagnosis in the post-operative period. Anaphylactoid reactions to HES are infrequent (0.08%). With regard to the manifestation and the degree of severity these reactions are not different from those observed after infusion of other colloids. Since the pathomechanism of anaphylactoid reactions to HES is still unknown prophylactic measures are not available. The elimination of HES from the circulation follows a protracted course, therefore accumulation of HES in tissues may occur after repeated infusions presenting a clear disadvantage of HES. There is, however, evidence that starch-preparations will be available in the future presenting an adequate volume effect while the elimination from the organism occurs rapidly. Low molecular hydroxyethylstarch (HES 450000, DS 0.5-0.55) yields inadequate volume effects; for this, low molecular HES can neither be recommended for long-lasting volume replacement nor for preoperative hemodilution.

Amylases↗
PubMed1978

[Sideeffects of colloids (author's transl)].

A prospective controlled trial during 1975 and 1976 has revealed that none of the colloids in clinical use (plasma protein solution, gelatine, hydroxyethylstarch and dextran) is free from the risk of anaphylactoid reactions. Even though the incidence of anaphylactoid reactions is low (0.03%), lethal outcome might be encountered. Between the colloids differences exist as far as manifestation (skin, circulatory and respiratory system) and degree of severity (I--IV) of anaphylactoid reactions are concerned. Since the underlying pathomechanisms have not been elucidated yet, true prophylactic measures are unknown. Therefore, it is mandatory to control the patient very carefully at the beginning of infusion; early symptoms of anaphylactoid reactions should trigger immediate therapeutic measures. Recent findings showed that the anaphylactoid reactions to dextran might be elicited by immune complexes. A new model was developed to investigate the chances of specific prophylactic procedures.

Anaphylaxis↗