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Biomedical subjects

W Erdmann

Publications and source records attributed to W Erdmann.

At least 127 records · Page 7Linked to original sources
PubMed1981

Pharmacokinetics of 4-aminopyridine in human volunteers. A preliminary study using a new GLC method for its estimation.

The concentrations of 4-aminopyridine hydrochloride in the blood and urine from volunteers were measured following a bolus injection i.v. of 0.3 mg kg-1. The drug was assayed by means of a new GLC method which is described. The pharmacokinetics of 4-aminopyridine are complicated by an additional increase in plasma concentration during the elimination phase of the drug.

4-Aminopyridine↗
PubMed1981

[Cardiocirculatory and respiratory effects of the combination of midazolam and ketamine].

This study summarizes our results with various ataralgesic combinations and their effects on circulation and respiration. Together with the new water-soluble 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine midazolam, Ro 21-3981, Dormicum), 7-chloro-1,3-dihydro-1-methyl-5-phenyl-(2H)1,4-benzodiazepin-2-one (diazepam) and 5-(o-fluorophenyl)-1,3-dihydro-1-methyl-7-nitro-2H-1,4-benzodiazepin-2-one (flunitrazepam) are also considered, for the purpose of comparison. Pharmacokinetic studies confirm the clearly shorter duration of action of midazolam. The poor respiratory depressant action of the benzodiazepines can be easily and rapidly increased by premedication, ataralgesic combinations and substances for the prolongation of anaesthesia. Adequate spontaneous respiration is possible only in exceptional cases. The threshold doses for 100% suppression of cardiac stimulation due to 2-(o-chlorophenyl)-2-methylaminocyclohexanone (ketamine) were determined for all three benzodiazepines. These doses are also valid for hypertension. The effect of intubation is not suppressed by the ataralgesic combination alone, whereas it does suppress the increase in pressure in the pulmonary circulation which is synchronous with the systemic blood pressure. The rise in intracranial pressure following ketamine alone is also prevented by premedication with benzodiazepines, which on the other hand offer no protection against certain other effects (hypoxia, hypercapnia, intubation), The same is true for increases in intraocular pressure. According to the results of investigations carried out, the new benzodiazepine midazolam justifies our hope for a substance with a similar basic effect, but with a clearly improved pharmacokinetic profile.

Adolescent↗
PubMed1980

Antagonism of ketamine-diazepam anaesthesia by 4-aminopyridine in human volunteers.

Five healthy human volunteers were anaesthetized on two separate occasions, 1 week apart, using a standard diazepam-ketamine induction followed by an infusion of ketamine for 1 h. Ten minutes after stopping the infusion, either 4-aminopyridine 0.3 mg kg--1 in saline or the same volume of saline alone was administered i.v. It was concluded that 4-aminopyridine enhanced dramatically the rate of recovery of the subjects to full consciousness and normal motor co-ordination when compared with the saline controls.

Aminopyridines↗
PubMed1980

The neuromuscular blocking action of ORG NC 45, a new pancuronium derivative, in anaesthetized patients. A pilot study.

The neuromuscular blocking effects of the new monoquaternary analogue of pancuronium, Org NC 45, have been investigated in anaesthetized patients. In different doses administered as a single i.v. bolus or as an initial bolus followed by several small maintenance doses or by a continuous infusion. Org NC 45 appears to be approximately as potent as pancuronium, but has a more rapid onset of action, considerably shorter duration of action and faster recovery rate than pancuronium. It showed no cumulative effects even after 10 maintenance doses were injected in succession. Doses of 0.08 mg kg-1 provided ideal intubating conditions in 90--95 s. Infusions of Org NC 45 provided much smoother control of neuromuscular blockade than did pancuronium. No cardiovascular side-effects were noted even at the greatest dose (0.12 mg kg-1) used. Org NC 45 has clear advantages over pancuronium and represents a potentially valuable addition to the armamentarium of clinically useful muscle relaxants.

Anesthesia, General↗
PubMed1980

Controlled administration of oxygen with self inflating resuscitation bags.

Resuscitation bags were originally developed to ventilate patients under emergency conditions. Under circumstances where oxygen is available one should make full use of it. The problem of exact air enrichment for these bags has not been satisfactory solved until now. Therefore a system has been developed which furnishes controlled delivery of FIO2 during ventilation with self inflating resuscitation bags. This is obtained via a venturi device connected to the air inlet of the manual resuscitation bag. The FIO2 delivered to the patients from a self inflating bag was tested for values of 24, 30, 40 and 50% oxygen. The new system proved to be capable to delivery exact FIO2 in contrast with previously applied methods of oxygen delivery where this could never be achieved.

Humans↗
PubMed1979

Ro21-3981/ketamine anesthesia for the treatment of poor risk patients.

Two consecutive anesthetics were given to a young severely debilitated patient, who had recently had bone marrow transplantation. On both occasions a combination of a new benzodiazepine, Ro21-3981, and ketamine was used, the first with the patient breathing oxygen spontaneously, and the second under relaxation and artificial ventilation with pure oxygen. The findings suggest that this technique provides cardiovascular stability during anesthesia and rapid return to consciousness, free from emergence phenomena. The technique facilitated the early transport of the patient away from the recovery facilities.

Adult↗
PubMed1979

Effects of the analeptic drug, 4-aminopyridine, upon post-operative respiratory depression in patients. A preliminary study.

The analeptic agent, 4-aminopyridine, was given to patients who had undergone elective ear, nose and throat surgery and showed severe central respiratory depression due to intra-operative fentanyl administration. The respiratory depression due to fentanyl was found to be partially antagonised by 4-aminopyridine. In view of these preliminary findings it is suggested that the drug might find a use in combatting postoperative fentanyl-induced respiratory depression.

Aminopyridines↗
PubMed1979

Antagonism of the cardiovascular effects of ketamine by diazepam in volunteers.

In healthy volunteers pretreated with atropine (0.5 mg), ketamine given as a bolus i.v. injection (2 mg/kg) followed by an infusion of ketamine (1 mg/kg/hr) for one hour, caused a significant rise in blood pressure and heart rate. This cardiovascular stimulation was rapidly counteracted by diazepam (0.2 mg/kg i.v.) given when the response to ketamine was already maximal.

Adult↗
PubMed1978

Effects of acupuncture on tissue oxygenation of the rat brain.

Acupuncture has been claimed to be effective in restoring consciousness in some comatose patients. Possible mechanisms to explain alleged acupuncture-induced arousal may include vasodilatory effects caused by smypathetic stimulation which leads to an augmentation of cerebral microcirculation and thereby improves oxygen supply to the brain tissue. Experiments were performed in ten albino rats (Wistar) employing PO2 microelectrodes which were inserted into the cortex through small burholes. Brain tissue PO2 was continuously recorded before, during, and after acupuncture. Stimulation of certain acupuncture points (Go-26) resulted in immediate increase of PO2 in the frontal cortex of the rat brain. This effect was reproducible and was comparable to that obtained with increase of inspiratory CO2 known to induce arterial vasodilatation and thus capillary perfusion pressure. The effect was more significant as compared to tissue PO2 increases obtained after increase in inspiratory oxygen concentration from 21% to 100%. It appears that acupuncture causes increased brain tissue perfusion which may be, at least in part, responsible for arousal of unconscious patients.

Acupuncture Therapy↗
PubMed1977

Effects of acupuncture on tissue-oxygenation of the rat brain.

Acupuncture has been claimed to be effective in restoring consciousness in some comatose patients. Possible mechanisms to explain alleged acupuncture-induced arousal may include vasodilatory effects caused by sympathetic stimulation which leads to an augmentation of cerebral microcirculation and thereby improves oxygen supply to the brain tissue. Experiments were performed in ten albino rats (Wistar) employing PO2 microelectrodes which were inserted into the cortex of the animals through small burholes. Brain tissue PO2 was continuously recorded before, during, and after acupuncture. Stimulation of certain acupuncture loci (Go-26) resulted in immediate increase of PO2 in the frontal cortex of the rat brain. This effect was reproducible. The effect was comparable to that obtained with increase of inspiratory CO2 known to induce arterial vasodilatation and thus capillary perfusion pressure. The effect was more significant as compared to tissue PO2 increases obtained after increase of inspiratory oxygen concentration from 21% to 100%. It appears that acupuncture causes an increase of brain tissue perfusion which may be, at least in part, responsible for arousal of unconscious patients. Dilatation of cerebral vascular vessels and improvement of autoregulation in the brain by acupuncture stimulation may also explain the effectiveness of acupuncture in the treatment of migraine headache.

Acupuncture Therapy↗
PubMed1976

The significance of diffusion hypoxemia.

The phenomenon of "diffusion hypoxemia" seems to be a well-defined entity. To determine the degree of deoxygenation of the arterial blood due to diffusion hypoxemia, experiments were performed in monkeys which were anesthetized with ketamine, intubated, and allowed to breathe spontaneously. Blood PaO2 values were continuously monitored with the aid of an intra-arterially placed IBC PO2 electrode capable of instantly recording changes in oxygen tension. After stabilization of the blood PaO2 values with the animal breathing different mixtures of oxygen and nitrous oxide, the inspired mixture was abruptly changed to normal air. The blood PaO2 values did not show any significant fall in PaO2 with any mixture containing more than 21% oxygen. It is suggested that diffusion hypoxemia of any degree can be seen only if a patient is breathing a gas mixture containing no more than 21% oxygen.

Anesthesia, Endotracheal↗