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Biomedical subjects

D Kettler

Publications and source records attributed to D Kettler.

At least 127 records · Page 7Linked to original sources
PubMed1980

Neurophysiological effects of etomidate, a new short-acting hypnotic.

The neurophysiological effects of 0.3 mg/kg etomidate injected i.v. within 30 sec were investigated in 22 healthy volunteers, 7 of whom were premedicated with Thalamonal and fentanyl. About 30 sec after injection, a short period of delta activity (deep sleep) occurred in the EEG, successively normalizing within the next 6-8 min. EEG arousal reactions to various stimuli were blocked for several minutes. In the premedicated group neither motor hyperactivity nor monosynaptic reflex alterations were observed. In contrast, 9 out of 5 non-premedicated subjects exhibited various kinds of motor hyperactivity, consisting most often of asynchronous clonic bursts of activity in the EMG. Clonus was not related to EEG events, and could persist beyond behavioural and EEG recovery. In 12 subjects, the monosynaptic H reflex was enhanced up to 6 X of control. The plantar reflex was reinforced to a generalized withdrawal reaction, sometimes a positive Babinski sign was observed. It is assumed that clonus is generated in spinal circuits, whereas supraspinal structures may contribute to the more complex forms of motor hyperactivity.

Adult↗
PubMed1980

[The effects of midazolam on the general, coronary and cerebral circulation (author's transl)].

The effects of midazolam (0.3 mg/kg body weight) on cardiovascular haemodynamics, coronary blood flow and cerebral blood flow were studied in fentanyl/halothane anaesthetized and artifically ventilated dogs. There was only a slight decrease in mean aortic pressure and dp/dtmax. Heart rate, cardiac output, coronary bood flow and myocardial oxygen consumption essentially remained unchanged. Cerebral blood flow and cerebral oxygen consumption did not change significantly. Cerebral perfusion pressure slightly decreased due to a reduction in mean aortic pressure. Our results demonstrate that midazolam in induction doses exerts only minimal efffects on the general, coronary and cerebral circulation. Midazolam might be of benefit in clinical practice due to its rapid onset, short duration of action, minimal cardiovascular side effects and water solubility. However, these results from experimental animals have to be confirmed in man.

Anesthesia, General↗
PubMed1979

Clinical suitability and accuracy of a new combined system for the transcutaneous and intravascular determination of PO2.

The clinical suitability and accuracy of the Hoffmann-La Roche continuous oxygen partial pressure measuring system, consisting of transcutaneous and intravascular probes, modules and recorder, was tested in routine use in a unit for vascular and heart surgery of the University Clinic in Göttingen. The stability of the system was good, accuracy was sufficient for clinical purposes (compared with a conventional discrete blood gas analysis technique) and practical suitability was good in routine use. The unit was simple to use, provided preparatory and calibratory steps were completed with necessary care and precision. Based on our experience with the unit, it is correct to say that it represents a refined and sufficiently accurate method suitable for use under clinical conditions. The need for strict adherence to the operating instructions must, however, be emphasized if incorrect measurements are to be avoided.

Adolescent↗
PubMed1979

[The effects of halothane-, nitroprusside- and trimethaphan-induced hypotension on cerebral blood flow and intracranial pressure (author's transl)].

Arterial hypotension to about 50 mm Hg mean pressure was induced in anaesthetized and artificially ventilated dogs by halothane, nitroprusside, and trimethaphan to study their effects on cerebral blood flow and intracranial pressure during hypotension. During nitroprusside induced hypotension there was a 32% increase in cerebral blood flow above control and a marked decrease in cerebral arteriovenous oxygen content difference indicating luxury perfusion of the brain. Cerebral blood flow remained high even 30 min after termination of hypotension. During halothane and trimethaphan hypotension cerebral blood flow remained unchanged. In all groups epidural pressure did not change substantially during hypotension but increased during recovery from nitroprusside hypotension by a maximum of 72% above control. It is concluded that during and after nitroprusside hypotension loss of cerebral autoregulation occurs which may result in a marked rise in intracranial pressure. Special vulnerability seems to exist shortly after termination of induced hypotension when arterial pressure begins to rise and brain perfusion follows a pressure-flow relationship.

Animals↗
PubMed1978

[Effects of isovolaemic haemodilution on pulmonary gas exchange and haemodynamics (author's transl)].

In experiments on 11 closed chest dogs the behaviour of pulmonary gas exchange and haemodynamics during isovolaemic haemodilution with 6% dextran was studied. The dogs were ventilated artificially (IPPB, PEEP = 0) with room air. After haemodilution a slight increase of arterial PO2 from 86 to 92 mm Hg was found. In another series of experiments an inspiratory O2-concentration of 25% was applied resulting in an increase of arterial PO2 from 106 to 113 mm Hg. In both series a decrease of alveolararterial PO2 gradients was observed. Effective pulmonary capillary blood flow varied in accordance with changes of cardiac output. Thus intrapulmonary shunt is supposed to have remained constant. The changes of pulmonary O2 diffusing capacity could be explained by the effect of haemodilution per se. At the end of the experiments ventilation was changed by adding a positive endexpiratory pressure of 8 cm H2O resulting in a decrease of arterial PO2 and a steep fall of cardiac output. In conclusion, isovolaemic haemodilution leads to only negligible variations of pulmonary gas exchange which should not be of any clinical importance.

Animals↗
PubMed1976

[Haemodynamics, oxygen demand and oxygen uptake of the heart during isovolaemic haemodilution (author's transl)].

1. In experiments on 5 closed chest dogs an isovolaemic haemodilution with 6% dextran resulted in a drop of haemoglobin content to 6,4g%. Except for a small decrease of arterial pO2 and O2-saturation the body oxygen supply remained undisturbed. -- 2. According to only very small haemodynamic alterations (except compensatory cardiac output increase) myocardial O2-demand increased very little and mainly is caused by moderate augmentation of ventricular wall tension. The decrease of arterial O2 content was fully compensated by an increase of myocardial blood flow. O2 supply to the myocardium was not critically changed. -- 3. In accordance with other investigators it is concluded that in case of coronary insufficiency or increased myocardial O2 demand intentional hemodilution should be avoided. Patients with myocardial insufficiency considered for therapeutic hemodilution should be digitalized preoperatively.

Animals↗
PubMed1975

[Improvement of myocardial blood flow and cardiac hemodynamic by means of intraaortic balloon pumping IABP during experimental heart failure (author's transl)].

The influence of the intraaortic balloon pumping (IABP) on the hemodynamic and coronary blood flow under control conditions and after experimental heart failure induced by coronary artery ligature was proved on eight dogs. By timely use of IABP (systolic pressure over 60-70 mmHg), the cardiac hemodynamics can be improved by means of reducing myocardial oxygen demands, and on the other hand by raising the coronary perfusion and oxygen supply.

Animals↗
PubMed1975

[Diagnostic and therapy of postoperative cardiac low-output-syndrome by means of intraaortic balloon pumping (IABP) or external counterpulsation (ECP)--a comparison (author's transl)].

A beneficial influence on the myocardial energy imbalance of the hypoxaemically damaged heart can be reached with either intraaortic balloon pumping (IABP) or external counterpulsation (ECP). In the realm of our acquired clinical experience with two groups of patients, the technical demands of these cardiac assist devices are discussed and distinguished from one another in relation to different indications.

Adult↗
PubMed1975

Effects of thiopental (Trapanal) on coronary blood flow and myocardial metabolism in man.

The influence of thiopental (Trapanal) on coronary blood flow (MPF), myocardial oxygen consumption (MVO2), and general haemodynamics was investigated in seven patients without heart disease. Besides measurement of MBF, the amount of substrates (glucose, lactate, pyruvate and free fatty acids (FFA) was also determined in arterial and coronary sinus blood samples. Thiopental was given intravenously in a mean dose of 4 mg/kg b,w, MBF was measured by means of the argon method. After injection of thiopental, all seven patients showed a significant increase of MBF and MVO2, a fact which can essentially be explained by the increase of heart rate. The effects of thiopental on arterial concentrations, arterior-coronary substrate differences, myocardial uptake, and O2-extraction ratio of the different substrates are discussed.

Adult↗