Biomedical subjects

H W Fischer

Publications and source records attributed to H W Fischer.

114 records · Page 7Linked to original sources

PubMedDate not supplied

Clinical comparison of Hexabrix, iopamidol, and Urografin-60 in whole body computed tomography.

Urografin 60, iopamidol and Hexabrix were studied in patients undergoing body CT scans to examine the pharmacodynamics of these contrast agents. Immediately following rapid injection, the lower osmolality media, Hexabrix and iopamidol, gave greater aortic concentration of iodine in addition to higher concentrations in the liver and spleen. These two agents also provided significantly better renal enhancement than Urografin 60, with Hexabrix giving higher levels than iopamidol. The higher early vascular concentrations of Hexabrix and iopamidol and the relative absence of side effects due to hyperosmolality and decreased toxicity may have advantages in dynamic CT scanning.

Contrast Media↗

PubMedDate not supplied

Cardiovascular responses to the intravertebral artery injection of hypertonic contrast media in the dog.

Central nervous system-mediated cardiovascular responses to contrast medium (CM) are believed the result of a vagal or of a sympatholytic response; these effects may be enhanced in the setting of dehydration. The purpose of this investigation was to evaluate neurally mediated effects of intravertebral artery CM injections on blood pressure (BP), heart rate (HR) and regional vascular resistances in euvolemic and dehydrated dogs. Animal preparation consisted of food and water ad libitum (n = 7) vs. 2.0 ml/kg i.m. furosemide and 48 hours thirsting (n = 7). During pentobarbital anesthesia BP, HR and renal and femoral blood flows were continuously monitored and meglumine iothalamate 60% (1 ml/kg) injected via a left vertebral artery catheter at 3 ml/sec; matched volume injections of normal saline served as control. Decreases in BP, HR and femoral and renal vascular resistances post CM injection were observed in the first 10 seconds before the CM had reached the systemic circulation. Significant decreases in both BP (-10.6 +/- 1.7%) and HR (-11.5 +/- 1.6%) post CM injection were noted with dehydration (n = 7). In the euvolemic dogs (n = 7) the decrease in HR (-7.3 +/- 2.0%) was significant but the decrease in BP (-3.9 +/- 2.4%) was not. The decrease in femoral vascular resistance was -22.7 +/- 9.0% in euvolemic dogs and -21.9 +/- 8.8% in dehydrated dogs. No significant changes were noted with the intravertebral artery injections of normal saline in control euvolemic and dehydrated animals. The early cardiovascular responses to CM suggest a direct action on the vasomotor center of the medulla. The effects on BP and HR are more severe in the dehydrated than in the euvolemic state.

Animals↗

PubMedDate not supplied

Effect of dextran on cerebral function and blood after cardiac arrest. An experimental study on the dog.

EEG activity and regional cerebral blood flow were monitored during 5 hour survival following cardiac arrest in 32 pentobarbital anesthetized mongrel dogs. The animals were mechanically ventilated and blood gases were maintained at physiologic levels. Regional cerebral blood flow and cardiac output were measured using 15 mu microspheres. EEG was recorded from 6 epidural electrodes using bipolar techniques. The animals were divided into 3 groups. The animals in Group I had an arrest of 8-11 minutes and those in Group II and III had an arrest of 12-16 minutes. Group II animals received no treatment. Group III animals were given 1 g/kg of dextran 40 at a concentration of 10% in normal saline following the arrest and maintained with 10 mg/kg/min during the 5 hours of recovery. In Groups I and III there was shorter duration of a flat EEG and 5 hours after the arrest the EEG activity was closer to normal than in Group II. After 5 hours the EEG scores of Group III were significantly greater than Group II (p less than 0.03). The cortical grey matter and hippocampus had the greatest reduction of blood flow following cardiac arrest. The mean cortical grey matter blood flow in Group II was less than in Groups I and III at 3 hours. After 5 hours the grey matter blood flow was greater in Group III than in Group II (p less than 0.09). The findings of this study are consistent with the hypothesis that after cardiac arrest perfusion abnormalities persist or develop after return of blood pressure and that these can be corrected or prevented with improved functional survival by treatment with dextran 40 after the arrest.

Animals↗

PubMedDate not supplied

Cardiovascular responses to the intracarotid injections of ionic contrast media and iohexol in the dog.

Hypotension and bradycardia are the most significant cardiovascular responses resulting from intracarotid injections of hypertonic contrast media (CM). We have assessed both local and systemic vascular responses to the selective intracarotid injections of ionic and non-ionic CM in twelve pentobarbital anesthetized dogs. Alterations in blood pressure, heart rate, and femoral, renal and carotid blood flows were monitored following right common carotid artery injections of ionic contrast media (282-288 mg I/ml), isotonic saline, and iohexol (300 mg I/ml). Ionic CM led to early (0 to 10 s) decreases in blood pressure, heart rate and femoral vascular resistance. Isotonic saline induced no significant early changes in these same parameters while iohexol caused a decrease in heart rate. Our observations suggest that the early (0 to 10 s) decreases in femoral vascular resistance, heart rate and pressure that occur with the intracarotid injection of hypertonic CM are mediated via the autonomic nervous system and initiated from a site in the carotid circulation. During the 15 to 40 s period when the CM has reached the systemic circulation, iohexol produced smaller effects on systemic blood pressure and peripheral vascular resistances than did the ionic CM. During this 15 to 40 s period there were decreased vascular resistances in the carotid and renal vascular beds that probably result from local effects of the CM, however, the femoral resistance was actually increased. This later increase in femoral resistance probably represents the results of increased sympathetic nervous system activity working to offset the decrease in renal and carotid resistances and thus maintain pressure at baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

A comparison of the cardiovascular responses to carotid injections of ionic and nonionic contrast media.

Selective injection of contrast media into the canine common carotid artery results in alterations in carotid flow, heart rate, and systemic arterial pressure. In this study the responses to injections of the nonionic agents metrizamide and iopamidol were compared to the responses to the ionic agents meglumine iothalamate, meglumine sodium diatrizoate, mannitol, and saline solution. Heart rate and pressure responses were smallest for metrizamide, greater for iopamidol, and greater still for the hypertonic ionic agents: responses were roughly correlated to agent osmolality. Carotid flow increased with all agents and was roughly proportional to the agent's osmolality. The exception was metrizamide which despite its lowest osmolality, produced a large increase in flow which was maintained much longer than for other agents. The total response to the nonionic agents was judged less severe than to the ionic agents; however, the responses to all agents were transient and not life threatening.

Animals↗

PubMedDate not supplied

Pulmonary edema following high intravenous doses of ionic contrast media. Effect of the anion composition and concentration.

High intravenous doses of diatrizoate are known to induce a profound degree of pulmonary edema which is dose- and injection rate-dependent in the rat. In this study, meglumine salts of diatrizoate, iothalamate, and metrizoate were evaluated for their capacity to induce pulmonary edema following intravenous injections. Differences in anion composition or concentration of diatrizoate meglumine/sodium salts did not cause significantly different degrees of pulmonary edema.

Animals↗