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Biomedical subjects

K Geiger

Publications and source records attributed to K Geiger.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Atrophy of the ganglion cells reduces pattern ERG not only in fine but also in coarse test patterns].

The pattern electroretinogram (PERG) is thought to be generated by the retinal ganglion cells. For coarse patterns, however, it has been suggested that the PERG is due to nonlinear summation of luminance responses. To test this hypothesis, we recorded the PERG in 8 patients with unilateral complete optic atrophy due to trauma or advanced glaucoma. Stimuli were phase-reversing checkerboards (7.8/s) with checks of 0.8 degrees and 15 degrees in size and with flashes. Retinal stimulation subtended 26 degrees x 34 degrees. In all 8 subjects, the PERG was greatly diminished using a check size of 0.8 degrees. With a check size of 15 degrees, the PERG was similarly diminished, while the flash responses were not reduced. Any overall luminance component of the stimulus, e.g., incomplete balance of light and dark areas, evoked strong luminance responses both in normal eyes and in eyes with optic nerve atrophy. Thus, intact ganglion cells seem to be necessary for a normal PERG regardless of the coarseness of the pattern. It is possible that different mechanisms (variable ganglion cell classes) contribute to the PERG response with different check sizes. Earlier reports, contradictory to these findings, are discussed. If the PERG reflects ganglion cell function even for large check sizes, stimulation of the ganglion cells with less optical degradation would be possible, enlarging its range of applications.

Attention↗
PubMed1991

[Selective intestinal decontamination--yes or no?].

Various studies have shown that as a result of selective decontamination of the digestive tract, the incidence of pneumonia in artificial ventilation caused by gram-negative bacteria is reduced; however, a few studies have pointed out that, at the same time, the rate of pneumonia caused by gram-positive bacteria is increased. Most investigators agree that mortality cannot be reduced. A few studies have demonstrated that simultaneous administration of cefotaxime is not necessary. Various recent reports indicate that under certain conditions selective decontamination of the digestive tract undoubtedly leads to the development of resistance to gram-negative bacteria and in particular, to oxacillin-resistant staphylococci, S. epidermidis, and enterococci. Multicenter, randomized, and prospective double-blind studies will have to investigate and establish definitively which antibiotics have to be applied in which patients in order to reduce the rate of pneumonia as well as mortality. In addition, these studies will have to determine the microbiological and hospital hygiene measures necessary to avoid the risk of resistance or colonization developing by certain agents. As long as this is not the case, broad, non-selective use of SDD is not justified, especially in intensive care units.

Anti-Bacterial Agents↗
PubMed1990

Differences in effects of isoflurane and enflurane on splanchnic oxygenation and hepatic metabolism in the pig.

The effects of end-tidal concentrations of 1.45% isoflurane and 2.12% enflurane on splanchnic blood flow (electromagnetic flow probes), oxygen (O2) extraction and surface PO2 (Clark-type electrode), and hepatic metabolism (organic acids) were compared in an animal model relevant to humans. Eighteen laparotomized, ventilated pigs, anesthetized and paralyzed with ketamine/flunitrazepam and pancuronium, were studied. Enflurane caused significantly (P less than 0.05) greater decreases in mean arterial pressure, cardiac output, and superior mesenteric arterial, portal, and total hepatic blood flows. In addition, hepatic arterial blood flow decreased during enflurane administration but increased markedly (40%) during isoflurane administration. However, mean surface PO2 of liver and small intestine decreased to similar degrees (20%) during isoflurane and enflurane. Summary histograms of surface PO2 values were leftward shifted but did not show O2 values in the hypoxic range (0-5 mm Hg). Except for a decrease in hepatic lactate uptake during enflurane, there were no changes in either hepatic uptake or release of organic acids during anesthesia with either agent. These data show that splanchnic O2 supply is better maintained during isoflurane than during enflurane. Although this was not reflected in differences in tissue oxygenation and metabolism, decreased portal and hepatic venous O2 contents during enflurane indicate that an increase in preportal and hepatic oxygen extraction was necessary to preserve tissue oxygenation.

Animals↗
PubMed1989

Influence of architectural design on nosocomial infections in intensive care units--a prospective 2-year analysis.

Nosocomial infection rates in an old intensive care ward constructed in 1924 were compared with those in a new one constructed in 1986. The nosocomial infection rate in the old unit was 34.2% and that in the new unit 31.9%, with an average of 33%. The most frequent infections were: pneumonia, urinary tract infection, septicaemia and wound infection. After transfer of the intensive care unit (ICU) the incidence and profile of nosocomial infections remained the same. These findings suggest that the influence of architectural design has little impact on the incidence of nosocomial infections.

Cohort Studies↗
PubMed1987

[Metabolism-oriented postoperative nutritional therapy--possibilities and limits in the use of glucose and xylitol].

Carbohydrates and polyols are essential constituents of intravenous nutrition. In order to better understand the problems associated with the supply of energy sources, the physiology of enteral nutrition will be covered and compared with intravenous nutrition. This review article will deal with the metabolic actions of glucose and xylitol and derive therapeutical consequences for their intravenous use during different illnesses.

Alanine Transaminase↗
PubMed1987

[Anesthesia in bronchial asthma].

Between 2% and 5% of the population suffer from bronchial asthma. The disease is characterized by bronchial hyperreactivity to physical, chemical, pharmacological, and/or immunological irritants. The incidence of perioperative complications is higher in asthmatics than in non-asthmatics. Careful pre- and postoperative care can reduce complications in these patients. Successful management of an asthmatic patient undergoing anesthesia starts with the identification of patients with asthma, the preoperative assessment, and evaluation of the pulmonary function. No elective surgery should be performed in patients suffering from unstable asthma or an acute attack. Thorough knowledge of the effects and interactions of broncholytic therapy with anesthesia is mandatory. Preanesthetic management must take into consideration the etiology of the disease; intraoperatively, attention must be paid to the pathophysiology. Appropriate perioperative monitoring can help to prevent complications. No one type of anesthesia is associated with lower postoperative complications. The skill of the anesthesiologist, early recovery from general anesthesia, and good postoperative care greatly reduce the incidence of complications. Besides the changes in pulmonary function that occur following anesthesia and surgery, asthmatics may suffer from abnormalities in control of ventilation and mucociliary function postoperatively. The patient with a history of asthma needs close supervision during the postoperative period: many sudden deaths from asthma and many episodes of ventilatory arrest occur during the night and in the early morning.

Anesthesia↗
PubMed1986

Side effects of positive pressure ventilation on hepatic function and splanchnic circulation.

Positive pressure ventilation is associated with a reduction and redistribution of cardiac output. Splanchnic blood flow is decreased. Blood supply of the liver is reduced exceeding the fall in cardiac output. As a result oxygen transport to the mesenteric bed and liver is curtailed. There is a concomitant impairment of hepatic venous outflow. These hemodynamic changes may cause functional, structural and metabolic disturbances in organs whose blood supply arises from splanchnic circulation.

Bile Ducts↗
PubMed1984

[Supine thoracic images with a mobile roentgen unit: comparison between the soft-ray and hard-ray technics].

To compare the influence of kilovoltage on the quality of supine chest roentgenograms obtained with a mobile x-ray unit, we examined the films of 50 patients on whom supine chest radiographs had been taken incidentally within a period of 24 hours both with high and with low-kVp technique. For evaluation of the image quality, a total of 11 criteria were compared and quantitated by 5 observers using a simple score method. The same advantages that have been attributed to the high-kVp technique on upright films were found on the corresponding supine examinations. These films showed a more balanced penetration and greater sharpness than those taken with low-kVp. The wider latitude of the high-kVp technique simplifies the exposure, and fewer repeat takes will therefore be necessary. The diagnostic gain outweights the few disadvantages, which are mostly coupled to the increase in scattered radiation. This, as well as the availability of more powerful and efficient mobile generators, should promote routine application of high-kVp technique for supine chest examinations.

Humans↗
PubMed1982

[Anesthesia in concomitant bronchopulmonary diseases].

The goal of any anaesthesiologist delivering anaesthesia to patients with pre-existing lung disease has to be the prevention of intra- and postoperative complications. Changes in gas exchange imposed by anaesthesia and surgery can cause dangerous disturbances in oxygen transport and in acid-base balance. Uptake and elimination of volatile and gaseous anaesthetics depend upon normal respiratory function. Any marked impairment can considerably modify the kinetics of these processes.

Acid-Base Equilibrium↗
PubMed1981

[The need for a specific postoperative, total parenteral nutrition therapy after various intra-abdominal procedures].

119 metabolically healthy surgical patients, who had to undergo elective intraabdominal surgery, were separated into upper -- cholecystectomy, gastric resection -- and lower -- colonic and sigma surgery -- intraabdominal procedures and divided into 8 groups with different infusion regimes. During the early postoperative period patients with upper abdominal surgery had significantly higher postoperative enzyme changes compared with patients with lower abdominal surgery. Patients with cholecystectomy had the significantly highest postoperative enzyme changes. On postoperative day 6 the enzyme changes showed a significant dependence from the duration of total parenteral nutrition, the chosen calorie-nitrogen-ratio, and the chosen energy substrate, xylitol or glucose. We could show a significant negative correlation between the extent of the stimulation of hepatic lipid synthesis and the protein parameters. Of all chosen infusion regimens xylitol in a dose of 0.11 g/kg BW X h together with the high amino acid infusion rate of 1.76 g/kg BW X day had the most favourable effect on the extent of stimulation of hepatic lipid synthesis, the late postoperative enzyme changes and the synthesis rate of visceral proteins. This study could demonstrate, that different intraabdominal surgical procedures need a more specific nutritional therapy.

Abdomen↗