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Biomedical subjects

K Holl

Publications and source records attributed to K Holl.

27 records · Page 2Linked to original sources
PubMed1989

Chronic cerebrovascular insufficiency on the xenon CT scan.

Several investigators have described CT-negative low flow areas in TIA and stroke patients in the chronic phase. The emission tomographic SPECT image they employed has, in contrast to the xenon CT method, no direct relation to the x-ray transmission CT scan. The aim of our study was to study the phenomenon of CT-negative low flow areas using the xenon CT method, a method especially well suited for such cases. 57 xenon CT examinations were performed in 40 TIA patients. Flow data from brain tissue which appeared to be anatomically intact in a slice 5 cm above the canthomeatal plane were analyzed. In the TIA group, the flow in the gray matter was found to be significantly lower on the clinically affected side: symptomatic side, 61.8 +/- 14.7 ml/100 g/min; asymptomatic side, 66.4 +/- 15.8 ml/100 g/min (p less than 0.001). In the stroke group, the flow in the white matter was also affected; symptomatic side, 31.2 +/- 9.8 ml/100, g/min; asymptomatic side, 35.3 +/- 11.1 ml/100 g/min (p less than 0.01). Gray matter: symptomatic side, 56.1 +/- 11.4 ml/100 g/min; asymptomatic side, 66.0 +/- 11.0 ml/100 g/min (p less than 0.001). The findings indicate that the appearance of CT-negative low flow areas in TIA and stroke patients during the chronic phase is the rule rather than the exception. Flow adaptation to anatomic changes not discernible by CT can be differentiated from clinically relevant flow impairment only by testing the cerebrovascular reserve.

Aged↗
PubMed1988

Improvement of global cerebral blood flow after STA-MCA bypass in a patient with bilateral occlusion of the internal carotid artery: effect of surgery or natural course?

A xenon-CT examination was performed on a patient who had received a STA-MCA bypass. Evaluation of cerebral blood flow (CBF) pre- and postoperatively shows a post-operative increase of about 60%. During manual compression of STA, a decrease of 20% was observed so that one third of the total CBF increase could be attributed to anastomosis. The remaining two thirds may originate from the natural collateral circulation.

Arterial Occlusive Diseases↗
PubMed1987

Stable-xenon-CT: effects of xenon inhalation on EEG and cardio-respiratory parameters in the human.

The effects of inhalation of a 33% Xenon-O2 mixture over a period of 5 minutes on EEG and cardio-respiratory parameters were studied in 18 human volunteers. This dosage is similar to that used clinically in Xenon-CT studies. In 4 cases no EEG power change was observed during the study. In the 14 other subjects EEG variations were seen. The most prominent change was an increase in beta EEG power. No change was observed in theta and delta EEG power. The findings seem to correlate with the early induction (excitation) phase of an anaesthetic. Hyperventilation was observed before the study and increased during the Xenon inhalation. Blood pressure remained stable while the heart rate tended to decrease a little. All these changes disappeared rapidly following the termination of the Xenon inhalation. The effects are minimal and should not reduce the clinical value of CBF measurement using the Xenon-CT method.

Administration, Inhalation↗
PubMed1987

EEG changes during five minutes of inhalation of a 33% xenon-O2 mixture.

The effects on the EEG of inhalation of a 33% Xenon O2 mixture over a period of 5 minutes were studied in 18 human volunteers. This dosage is similar to that used in xenon CT studies. In 4 subjects no EEG changes were observed during the study. In the 14 other subjects, EEG variations were detected, the most prominent of which was an increase in beta power. No change was observed in theta and delta power. These findings seem to support an early induction (excitation) phase of anaesthetics. All changes disappeared rapidly following the termination of xenon inhalation. The effects reported are minimal and should not impair the clinical value of CBF measurements using the xenon CT method.

Administration, Inhalation↗
PubMed1986

[Experience with the inhalation of a 33% xenon-(stable-)oxygen mixture in relation to a new method of measuring local cerebral circulation].

We describe a new non-invasive method for measuring local blood flow in the brain. Xenon (stable)-nl CBF-CT-method has been used in our clinic for the first time in Europe. It is superior to all other methods, such as 133Xenon, SPECT and PET in terms of anatomical accuracy and its resolution. We describe the method and its side effects. Inhalation of Xenon in sub-narcotic doses (33% for five minutes) produced no significant complications. Of 95 examinations, 74 were free of any incidents. The most common side effect was euphoria. The method appears to be suitable for general clinical use.

Cerebrovascular Circulation↗
PubMed1985

Evaluation of H2O2 prophylaxis of bacteriuria in patients with long-term indwelling Foley catheters: a randomized controlled study.

Since the long-term catheterized patient is at significant risk of urinary tract infection, and the catheter drainage bags of these patients are at significant risk of becoming reservoirs for nosocomial pathogens, we carried out a randomized, controlled study to determine the efficacy of intermittent drainage bag instillation of hydrogen peroxide (H2O2) in patients requiring indwelling Foley catheters for 5 days or more. Herein we report the effects of this technique on the rates of catheter and bag bacteriuria, the duration to positive culture, the temporal relationships observed, and the spectrum of organisms recovered. Bag source bacteriuria was found with the same frequency in both control and H2O2 groups. H2O2 did reduce contamination of the drainage bag but did not reduce catheter-associated bacteriuria or frequency of symptomatic urinary tract infection. Furthermore, H2O2 did not reduce the frequency of bag contamination with most of the common nosocomial urinary pathogens.

Antisepsis↗