PubMed Health⌕ Search

Biomedical subjects

L J Hellebrekers

Publications and source records attributed to L J Hellebrekers.

At least 19 recordsLinked to original sources
PubMed2001

Cardiopulmonary effects of three different anaesthesia protocols in cats.

To develop an alternative anaesthetic regimen for cats with cardiomyopathy, the cardiopulmonary effects of three different premedication-induction protocols, followed by one hour maintenance with isoflurane in oxygen: air were evaluated in six cats. Group I: acepromazine (10 microg/kg) + buprenorphine (10 microg/kg) IM, etomidate (1-2 mg/kg) IV induction. Group II: midazolam (1 mg/kg) + ketamine (10 mg/kg) IM induction. Group III: medetomidine (1.5 mg/m2 body surface) IM, propofol (1-2 mg/kg) IV induction. Heart rate, arterial blood pressure, arterial blood gases, respiration rate, and temperature were recorded for the duration of the experiment. In group I the sedative effect after premedication was limited. In the other groups the level of sedation was sufficient. In all groups premedication resulted in a reduced blood pressure which decreased further immediately following induction. The reduction in mean arterial pressure (MAP) reached statistical significance in group I (142+/-22 to 81+/-14 mmHg) and group II (153+/-28 to 98+/-20 mmHg) but not in group III (165+/-24 to 134+/-29 mmHg). Despite the decrease in blood pressure, MAP was judged to have remained within an acceptable range in all groups. During maintenance of anaesthesia, heart rate decreased significantly in group III (from 165+/-24 to 125+/-10 b.p.m. at t=80 min). During anaesthesia the PCO2 and PO2 values increased significantly in all groups. On the basis of the results, the combination acepromazine-buprenorphine is preferred because heart rate, MAP, and respiration are acceptable, it has a limited sedative effect but recovery is smooth.

Acepromazine↗
PubMed2000

The rat vertex-middle latency auditory-evoked potential as indicator of anaesthetic depth: a comparison with evoked-reflex testing.

We investigated whether components from the rat Vx-MLAEP could be used to assess depth of anaesthesia induced by propofol. Propofol decreased MLAEP amplitudes and increased latencies. We propose that the P(16)-N(22) wave in the rat MLAEP is similar to the human P1, and that recovery of this wave during propofol anaesthesia correlates with behavioural measures of the regaining of consciousness.

Anesthesia↗
PubMed2000

The effect of intravenous medetomidine on pupil size and intraocular pressure in normotensive dogs.

Medetomidine, a highly specific alpha-2 adrenergic agonist, has been demonstrated to lower intraocular pressure (IOP) in rabbits and cats when applied topically. The purpose of this study was to assess the influence of intravenously injected medetomidine on the pupil size (PS) and the IOP of non glaucomatous dogs. IOP was measured by applanation tonometry and PS was measured using Jameson calipers at t=0 (or time of IV injection of medetomidine (Domitor; Orion) at the dose of 1500 microg/m2 body surface area) and again after 5 minutes (t=5). The IV administration of medetomidine caused miosis in all 14 dogs. The mean PS decreased from 9.0 to 4.0 mm (p<0.001). The IOP was lowered in 10 dogs and in 4 dogs there was a rise in IOP. The mean IOP (mmHg) decreased from 22 to 21 (p>0.2). The data presented above confirm that medetomidine at a dose of 1500 microg/m2 body surface area produces miosis in non glaucomatous dogs, without influencing the IOP.

Adrenergic alpha-Agonists↗
PubMed1999

Effect of superior laryngeal nerve transection on pharyngeal muscle contraction timing and sequence of activity during eating and stimulation of the nucleus solitarius in dogs.

The effect of unilateral or bilateral transection of the superior laryngeal nerve on the electromyographic activity in the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles was studied in 10 dogs during eating and during unilateral electrical stimulation of the solitary nucleus. In all groups of dogs, after unilateral or bilateral transection, there were some swallowing actions in which the sequence of activity in the pharyngeal muscles was disturbed during eating and during stimulation of the solitary nucleus. In the dogs in which the transection was unilateral, this fraction was 18% in the ipsilateral muscles during eating and 7% in the contralateral muscles. After bilateral transection it was 8% in the left muscles and 16% in the right muscles. The fractions were not significantly different when swallowing was evoked by stimulation of the solitary nucleus. Swallowing actions having a normal sequence of activity in these dogs were compared with those in a group of eight dogs in which the superior laryngeal nerves were intact. Contraction timing was not significantly different during eating, but during stimulation of the solitary nucleus the timing was significantly shorter than in the dogs with intact nerves. It was concluded that superior laryngeal nerve transection modulates the central pattern generator for pharyngeal swallowing in dogs.

Animals↗
PubMed1999

EEG evaluation of reflex testing as assessment of depth of pentobarbital anaesthesia in the rat.

Electroencephalography (EEG) was applied to evaluate the validity of the paw pinch reflex as an indicator of anaesthetic depth in rats which are anaesthetized with a single intraperitoneal dose of pentobarbital. After induction of the anaesthesia, characterized by the rapid loss of the animals' ability to maintain upright posture, the EEG of 10 out of 11 rats was dominated by paroxysmal (burst suppression) activity, associated with unconsciousness. In seven out of 11 rats, the paw pinch reflex was lost after onset of paroxysmal electroencephalographic activity. However, the paw pinch reflex remained present in four out of 11 animals, demonstrating that the response is independent of cortical activity. In five out of seven rats, the EEG still showed paroxysmal activity when the paw pinch reflex was regained. However, in two other rats the EEG returned to a pattern similar to that shown by awake animals, 4 and 21 min respectively, before the reflex was regained. These data indicate that in the pentobarbital-anaesthetized rat, presence of the paw pinch reflex is not related to the level of depression of electrical activity in the cerebral cortex, and consequently is probably not related to the level of consciousness. Based upon these findings it is concluded that the paw pinch reflex is unreliable as a sole indicator of anaesthetic depth.

Analgesics, Opioid↗
PubMed1998

[Euthanasia of piglets: gas or injection?].

Methods for the humane killing of animals are watched critically by both the public and the veterinary community. Evaluation of such methods requires assessment of efficacy as well as emotional and ethical aspects. Rapidity of loss of consciousness is a crucial factor in such evaluations. In the present study, four methods for piglet euthanasia were compared with regard to presence of indicators of discomfort (pain, anxiety, stress) and rapidity of onset of death, defined as the absence of breathing, heart beats and reflexes, combined with isoelectricity of the electro-encephalogram (EEG). The study was performed on piglets, which had to be destroyed on account of preventive measures against swine fever. The following methods were applied: CO2 98%, CO2/O2 65/35%, T61 and pentobarbital (Euthesate) injected intracardially. Intracardial injections of T61 and pentobarbital provide fast unconsciousness and death with minimal discomfort to the animal.

Administration, Inhalation↗
PubMed1998

[Recent insights into the possibilities of resuscitation of dogs and cats].

This article reviews the present state of the art of resuscitation of dogs and cats. The purpose of resuscitation is to revive animals so that the vital functions resume together with a normal brain function. Resuscitation must be started as soon as the cardiopulmonary arrest has been confirmed. Adequate ventilation and effective circulation to the most vital body organs, the heart and the brain, have the highest priority. They can be achieved by endotracheal intubation, artificial ventilation with 100% oxygen and rhythmic compression of the closed chest or direct cardiac massage following thoracotomy. Medical therapy is an important part of resuscitation. In the absence of a central venous route, deep endotracheal administration is the preferred method of administration. Most medications can be administered through the endotracheal tube in this fashion.

Animals↗
PubMed1998

Clinical efficacy and safety of propofol or ketamine anaesthesia in dogs premedicated with medetomidine.

Combinations of medetomidine with either propofol or ketamine were compared for the sedation and induction of anaesthesia in dogs undergoing a variety of surgical (60 per cent) and non-surgical (40 per cent) procedures. Eighty-four dogs were used at four sites. Medetomidine was administered intramuscularly at a dose of 1000 micrograms/m2 body surface area 10 to 15 minutes before the induction of anaesthesia by the administration of propofol (n = 44) or ketamine (n = 40) dosed to effect. The dogs became sedated by medetomidine after a mean (sd) time of 6.7 (5.4) minutes, and their heart rates and respiration rates decreased. Sixteen of the dogs suffered an adverse effect, 13 of them vomited. Anaesthesia was induced by the intravenous administration of propofol (2.1 [0.7] mg/kg) or ketamine (3.7 [1.9] mg/kg), and further doses of the anaesthetic were given, depending on the length of the operation, once in 17 per cent, twice in 11 per cent and three or more times in 24 per cent of the cases. The heart rate of the dogs anaesthetised with ketamine was significantly higher than that of the dogs anaesthetised with propofol, but there were no other significant physiological differences. There were 11 adverse side-effects in the ketamine group compared with five in the propofol group and they were generally more severe. The quality of the recovery from anaesthesia was considered to be smooth in 89 per cent of the propofol group but in only 63 per cent of the ketamine group.

Anesthesia↗
PubMed1998

Effect of stimulating peripheral and central neural pathways on pharyngeal muscle contraction timing during swallowing in dogs.

The effect of stimulating peripheral and central neural pathways on the electromyographic activity in the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles was studied in eight dogs during 1) eating, 2) unilateral electrical stimulation of the superior laryngeal nerve, and 3) unilateral electrical stimulation of the solitary nucleus. The duration of pharyngeal swallowing was significantly shorter during eating than during stimulation of the solitary nucleus in the anesthetized dog (mean difference 127 ms, SEM 9, n = 15). The duration of pharyngeal swallowing was significantly shorter during eating than during stimulation of the superior laryngeal nerve in the awake dog (mean difference 84 ms, SEM 13, n = 9). The duration of pharyngeal swallowing during stimulation of the superior laryngeal nerve under anesthesia was significantly shorter than during stimulation of the solitary nucleus under anesthesia (mean difference 58 ms, SEM 18, n = 9). The difference in duration of pharyngeal swallowing during stimulation of the superior laryngeal nerve between the awake state and during anesthesia was not significant (mean 19 ms, SEM 14, n = 9). It was concluded that stimulation of peripheral and central neural pathways resulted in different pharyngeal muscle contraction timing during swallowing in dogs.

Animals↗
PubMed1997

Partition coefficients (n-octanol/water) of N-butyl-p-aminobenzoate and other local anesthetics measured by reversed-phase high-performance liquid chromatography.

For the determination of the logarithmic partition coefficients between n-octanol and water (log P(o/w)) of local anesthetics, the pH of the aqueous phase needs to be adjusted to high values to ensure that the local anesthetics are in the unionized form. Using the shake-flask or the stir-flask method, this high pH may catalyze hydrolysis, leading to increasing amounts of impurities in time. These impurities exclude non-selective quantification methods like UV spectrometry and require repetitive quantitative analysis of both liquid phases resulting in a tedious and time-consuming method. A rapid reversed-phase HPLC method was developed to measure log P(o/w) of the local anesthetics N-butyl-p-aminobenzoate, methyl-p-aminobenzoate, benzocaine, procaine, mepivacaine, prilocaine, lidocaine, bupivacaine, etidocaine, tetracaine and oxubuprocaine.

1-Octanol↗