I. Hadolt

Effects of acupuncture on the oxygenation of cerebral tissue

Monitoring of regional cerebral oxygen saturation (r. cereb. O2 satn.) was carried out continuously in 12 healthy subjects (mean age 35.2 +/- 4.4 years; range 26-41 years; 4 women, 8 men), prior to, during and following acupuncture. Measurements were obtained with the INVOS 3100 cerebral oximeter (Somanetics Corp., Troy, USA). In addition new robotic transcranial Doppler sonography (TCD) probes enabling three-dimensional imaging of the middle cerebral artery by the use of multi-scan techniques were used simultaneously. The results showed small increases in r. cereb. O2 satn. mean values (69.9% before, 70.3% during and 70.2% after acupuncture) and a significant (p < 0.01; ANOVA, Tukey test) increase in mean bloodflow velocity during acupuncture measured simultaneously at different depths within the right middle cerebral artery. There are reports in the literature about the effects of acupuncture on the oxygenation of cerebral tissue in a study with animals. An increase in the cerebral oxygen saturation could be registered with the help of microelectrodes in the cortex. This is parallel evidence to the present results with near infrared spectroscopy and transcranial Doppler sonography. Quantifiable changes in the physiological effects of acupuncture may contribute to improved acceptance of this unconventional complementary medical procedure.

Noninvasive assessment of cerebral oxygenation during high altitude trekking in the Nepal Himalayas (2850-5600 m).

Abstract Mountain trekking is significantly increasing in popularity. Hypoxia seems to play a key role in the pathogenesis of acute mountain sickness (AMS). The purpose of this study was to investigate regional cerebral (rSO2) and peripheral (SaO2) oxygen saturation for the first time, during 22 days high altitude trekking (measurement points: 3450, 4450, 4750, 5050 and 2850 m) in the Khumbu region of Nepal with near infrared spectroscopy and pulse oximetry. We examined 17 healthy volunteers 19–65 years old (8 female, 9 male; mean age ± SD, 46.1 ± 13.1 years). RSO2 and SaO were significantly (p < 0.001, ANOVA, Tukey test) decreased at high altitudes (4450, 4750 and 50502m). The decrease in cerebral oxygen saturation was more pronounced at higher altitudes than in the periphery (rSO2/SaO = 0.56 at 5050 m). At higher altitudes (> 4450 m), two subjects showed reversible symptoms of AMS. The present data indicates that acute reduction in rSO2 values might be a primary cause of AMS, however, further studies and analysis are necessary to correlate our findings with cerebral symptom scores.

Transcranial Optical Spectroscopy – A comparison of the TOS 96 and INVOS 3100 cerebral oximeters. Transkranielle optische Spektroskopie – ein Vergleich der zerebralen Oximeter TOS 96 und INVOS 3100

We evaluated two user-friendly, commercially available transcranial cerebral oximeters (TOS 96, Tostec, Tokyo, Japan and INVOS 3100, Somanetics, Troy, USA) for use in adults. We compared the absolute values (%) of regional cerebral oxygen saturation (rSO2) from 108 measurements in 54 healthy volunteers (31 women, mean age 35.8 +/- 16.3 years and 23 men, mean age 35.4 +/- 9.2 years). The mean rSO2 values obtained by the TOS 96 and INVOS 3100 systems were 72.3 +/- 8.4 % and 72.6 +/- 7.2% respectively. Significant differences (p < 0.01) were found between females and males with the INVOS equipment. The study shows that anatomical (thickness of the skull) and technical (calibration) aspects have to be taken into consideration when interpreting absolute rSO2 values.

Transkranielle Doppler-Sonographie - Robotergesteuerte Sonden zur Quantifizierung des Einflusses der Akupunktur - Transcranial Doppler Sonography - Robotic Probes for the Quantification of Acupuncture

Transcranial Doppler sonography (TCD) monitoring was carried out in 12 healthy subjects (mean age: 35.2 ± 4A years; range: 26-41 years; 4 women, 8 men), prior to, during and following acupuncture. In all subjects an identical acupuncture scheme with a general increase in Qi energy setting was employed. Measurements were obtained with new robotic TCD probes enabling three-dimensional imaging of the middle cerebral artery by the use of the multi-scan technique. The results showed a significant (p < 0.01; ANOVA; Tukey test) increase in mean bloodflow velocity measured simultaneously at different depths within the right middle cerebral artery. Quantifiable changes in the physiological effects of acupuncture may contribute to improved acceptance of this unconventional complementary medical procedure.

Regional differences in the cerebral blood flow velocity response to hypobaric hypoxia at high altitudes.

Symptoms of acute mountain sickness (AMS) may appear above 2,500 m altitude, if the time allowed for acclimatization is insufficient. As the mechanisms underlying brain adaptation to the hypobaric hypoxic environment are not fully understood, a prospective study was performed investigating neurophysiological changes by means of near infrared spectroscopy, electroencephalograpy (EEG), and transcranial doppler sonography at 100, 3,440 and 5,050 m above sea level in the Khumbu Himal, Nepal. Fourteen of the 26 mountaineers reaching 5,050 m altitude developed symptoms of AMS between 3,440 and 5,050 m altitude (Lake-Louise Score ≥ 3). Their EEG frontal beta activity and occipital alpha activity increased between 100 and 3,440 m altitude, i.e., before symptoms appeared. Cerebral blood flow velocity (CBFV) in the anterior and middle cerebral arteries (MCAs) increased in all mountaineers between 100 and 3,440 m altitude. During further ascent to 5,050 m altitude, mountaineers with AMS developed a further increase in CBFV in the MCA, whereas in all mountaineers CBFV decreased continuously with increasing altitude in the posterior cerebral arteries. These results indicate that hypobaric hypoxia causes different regional changes in CBFV despite similar electrophysiological changes.

Prognostic value of cerebral near infrared spectroscopy and cerebral blood flow velocity for developing acute mountain sickness at high altitudes

Using near infrared (NIR) spectroscopy and transcranial Doppler sonography (TCD), we investigated the effects of high altitude in a group of 17 healthy volunteers (mean age ± standard deviation: 46.1 ± 13.1 years) during a common trekking tour in the Nepal Himalayas, lasting 22 days (2850 m to 5600 m). Values of regional cerebral oxygen saturation (rSO2) obtained by an INVOS 5100 system significantly decreased (p < 0.001) compared to baseline (130 m) at an altitude of 4450 m. Mean blood flow velocity (v m ) in the middle cerebral artery measured by a portable Smart Dop equipment significantly increased (p < 0.05) compared to baseline (130 m) also at an altitude of 4450 m. The results showed further that all three subjects who developed acute mountain sickness (AMS) and who were not able to continue the trek up to 5050 m, had rSO2 or v m values out of the normal range at baseline measurements 130 m above sea level 53 days before starting the tour. Simultaneous measurement of cerebral rSO2 and v m parameters could be able to enhance the prognostic accuracy for the development of AMS in the mountain trekking population.

Zur Problematik der Emboliedetektion bei der transkraniellen Doppler-Sonographie - Neueste technische Entwicklungen

EINLEITUNG: Die Transkranielle Doppler-Sonographie (TCD) spielt in der operativen und intensivmedizinischen Überwachung auf Grund ihrer Nichtinvasivilät eine immer größere Rolle [1]. Die Inzidenz für eine venöse Luftembolie bei neurochirurgischen Eingriffen wird in der Literatur mit 20 40 % beschrieben [2]. Die Angaben zur Häufigkeil einer arteriellen (paradoxen) Luftembolie liegen zwischen 6 -12 %, wobei das tatsächliche Ausmaß nicht bekannt ist und die Dunkelziffer durchaus höher sein kann. Voraussetzung für das Auftreten einer paradoxen Luftembolie ist das Vorliegen eines intrakardialen oder mlrapulmonalen Rechts-links-Shunts (z. B. offenes Foramen ovale). Eine neue Methode der TCDEmboliedetektion könnte in der Lage sein, sowohl präoperativ im Sinne eines Screenings, aber auch intraoperativ online klinisch relevante Hinweise zu liefern.

Stimulationsinduzierte hirnelektrische Oszillationen bei gesunden Probanden

EINLEITUNG Durch die Darbietung von akustischen Reizen in Form von Klicks können vom intakten Schädel sogenannte akustisch evozieite Potentiale (AEP) abgeleitet werden. Je nach zeitlichem Auftreten der hirnelektrischen Antworten unterscheidet man AEP früher (0-10 ms), mittlerer (10-80 ins) und später (> 80 ms) Latenz [1]. Bei einer akustischen Stimulation mit einer Frequenz von 40 Hz und Ableitung der AEP mittlerer Latenz konnten Galambos u. Mitaib. 1981 [2] charakteristische sinusförmige Antworten ableiten. Dabei wird durch Supeiposition aufeinanderfolgender Potentialsequenzen mit einer um eine Periode verschobene Phasenlage eine Amplitudenerhöhung nach dem Resonanzprinzip ausgenutzt Der Sitz der Generatoren dieser sogenannten 40 Hz Antwort ist bis jetzt unklar, jedoch wird z. B. von Firsching die Entstehung im Thalamus-Mittelhirnbereich postuliert [3]. Auch umfassende Korrelationen der 40 Hz Oszillationen zu den AEP froher Latenz, die die Antwort des Hirnstamines repräsentieren, wurden noch nicht ausreichend untersucht.