Biomedical subjects

M De Vlieger

Publications and source records attributed to M De Vlieger.

10 recordsLinked to original sources

PubMed1985

Objective measurement of hepatic encephalopathy in pigs by means of spectral analysis and evoked responses.

Objective measurement of hepatic encephalopathy by means of spectral analysis of the electroencephalogram (EEG), visual-evoked potentials (VEP) and brainstem auditory-evoked potentials (BAEP) was studied in pigs with ischemic hepatic necrosis. The mean dominant frequency (MDF) and the relative power of the delta frequency band (% delta power) showed significant changes with increasing encephalographic grades of encephalopathy: MDF dropped from 7.0 +/- 0.5 (grade 0) to 2.7 +/- 0.3 Hz (grade 3 encephalopathy) and % delta power increased from 52 +/- 7 (grade 0) to 83 +/- 6% (grade 3). The patterns of the VEP in pigs corresponded to those of the human VEP. However, significant differences in either latency time of the peaks or the peak amplitude with increasing stages of hepatic encephalopathy could not be found. The BAEP registered for pigs were reproducible but also were not as useful as spectral analysis for grading hepatic encephalopathy.

Animals↗

PubMed1984

Objective measurement of hepatic encephalopathy by means of automated EEG analysis.

Automated analysis of the electroencephalogram as an objective measurement of hepatic encephalopathy for the individual patient was investigated. The mean dominant frequency of patients with grades 0 and 1 hepatic encephalopathy was in the normal range (greater than or equal to 6.4 Hz); grade 1 hepatic encephalopathy, however, was characterized by abnormal relative power of theta activity of more than 35%. Twelve out of 34 patients with clinical grade 0 hepatic encephalopathy also had an elevated power of theta activity and probably therefore latent hepatic encephalopathy. Patients with grades 2, 3 and 4 hepatic encephalopathy had a low mean dominant frequency (less than 6.4 Hz) and could be identified by a biphasic power spectrum (theta and delta peaks, grade 2) or by a high power of delta activity (greater than or equal to 70%, grade 3-4). We conclude that automated EEG analysis based on the parameters mean dominant frequency and the relative powers of the delta and theta band is very suitable for objective classification of hepatic encephalopathy in individual patients.

Adult↗

PubMed1984

Absence of electroencephalographic excitation pattern under isoflurane anesthesia.

In twelve patients the EEG was recorded under isoflurane--nitrous oxide inhalation anesthesia. A quiet EEG pattern was registered, without suppressions and seizures of spike activity which are often observed under enflurane. This was the case even when end expiratory CO2 shifted to low values (3-3.6 Vol%). In one patient the induction with N2O/O2 and thiopentone, resulted in spikes and suppression bursts on the EEG. After isoflurane was added, these changes disappeared. In another patient, epileptic EEG patterns were observed prior to the induction (confirmed by the history of the patient). During isoflurane anesthesia the epileptic waves disappeared and remained absent.

Adult↗

PubMed1978

Hemoglobin A2 levels in malaria patients.

The influence of malaria on the hemoglobin A2 (Hb A2) level in humans was studied in a series of 94 imported cases in Belgium. Sixty-nine of the patients were natives of Western European countries, their results are reported separately since their origin and the results of their hematological examination made it unlikely that they carried the beta-thalassemia trait. The Hb A2 level of the 94 malaria patients (mean 2.76%; S.D. 0.51%) was not statistically different from that found in 60 healthy controls (mean 2.70%; S.D. 0.38%; P greater than 40). Likewise the level of the 65 Western European patients was not statistically different from that of the same controls (mean 2.81%; S.D. 0.42%; P greater than 0.10). There was also no significant difference between the level in patients infected with a particular species of Plasmodium and that of the controls. No correlation was found between the Hb A2 level and the intensity of the parasitemia or the concentration of total hemoglobin in the blood. These results are discussed in comparison with the divergent ones obtained by others and it is suggested that malaria has no significant influence on the results of surveys for the prevalence of beta-thalassemia in regions of malaria endemicity.

Adult↗

PubMed1975

A directional quantifying Doppler system for measurement of transport velocity of blood.

A transcutaneous Doppler device has been developed that measures primarily the directional transport velocity of blood, averaged over the vessel diameter, irrespective of its flow in adjacent vessels. Directional information is obtained by high or low-pass filtering of frequency converted versions of the received Doppler signals, applying low-cost, sharp filters in a superheterodyne system. Upper and lower channel signals are quantified separately to average directional velocity. Linear results from in vitro measurements are obtained.

Animals↗

PubMed1969