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At least 1,333 records · Page 74Linked to original sources
PubMed2001

Sleep and wakefulness in somnambulism: a spectral analysis study.

OBJECTIVE: The sleep structure and the dynamics of EEG slow-wave activity (SWA) were investigated in 12 young adults and age- and gender-matched controls. METHODS: Polysomnography was performed in subjects with well-documented chronic sleepwalking and in matched controls. Blinded visual scoring was performed using the international criteria from the Rechtschaffen and Kales atlas [A manual of standardized technology, techniques and scoring systems for sleep stages of human subjects. Los Angeles: UCLA Brain Information Service, Brain Research Institute, 1968.] and by determining the presence of microarousals as defined in the American Sleep Disorders Association (ASDA) atlas [Sleep 15 (1992) 173.]. An evaluation of SWA overnight was performed on total nocturnal sleep to determine if a difference existed between groups of subjects, since sleepwalking usually originates with slow-wave sleep. Investigation of the delta power in successive nonoverlapping 4-second windows in the 32 seconds just prior to EMG activity associated with a confusional arousal was also conducted. One central EEG lead was used for all analyses. RESULTS: Somnambulistic individuals experienced more disturbed sleep than controls during the first NREM-REM sleep cycle. They had a higher number of ASDA arousals and presented lower peak of SWA during the first cycle that led to a lower SWA decline overnight. When the investigation focused on the short segment immediately preceding a confusional arousal, they presented an important increase in the relative power of low delta (0.75-2 Hz) just prior to the confusional arousal. CONCLUSION: Sleepwalkers undergo disturbed nocturnal sleep at the beginning of the night. The increased power of low delta just prior to the confusional arousal experienced may not be related to Stages 3-4 NREM sleep. We hypothesize that it may be translated as a cortical reaction to brain activation.

Adult↗
PubMed1997

Spectral analysis of heart rate and blood pressure in Guillain-Barré patients with respiratory failure.

The clinical value of heart rate and blood pressure variation (HRV and BPV) spectra was assessed in 11 consecutive patients with Guillain-Barré syndrome (GBS) on artificial ventilation. Their HRV and BPV spectra were compared with those from 28 control intensive care unit (ICU) patients without peripheral nerve disorders. ICU controls had low respiratory HRV during controlled ventilation. If present, it was closely related to, but smaller than BPV, suggesting baroreceptor reflex mediation. Respiratory HRV similar to that of healthy controls was observed only in ICU controls with significant spontaneous ventilation. HRV was prominent in a subgroup of GBS patients who suffered from bradycardia or sinus arrest, whereas GBS patients without episodic bradycardia only exceptionally had respiratory HRV. Interpretation of HRV during artificial ventilation cannot be extrapolated from experience with spontaneously breathing subjects. In contrast to diabetic neuropathy, not loss, but preservation of respiratory HRV was ominous in artificially ventilated GBS patients. A pattern of prominent broad respiratory HRV peaks and narrow BPV peaks occurred only in GBS and forebode sinus arrest.

Adult↗
PubMed1993

Nonvisual laser lithotripsy aided by plasma spectral analysis: viability study and clinical application.

Nonvisual laser lithotripsy implies laser fragmentation without the aid of endoscopic or direct vision. Using the laser delivery fiber for retrograde transmission of plasma spectrum and its analysis on an optical multichannel analyzer, we designed a project with the objective of identification and fragmentation of calculi by continuous analysis of the plasma feedback spectrum. We were successful in achieving the objectives in the in vitro and ex vivo studies. In the in vivo studies we successfully recorded the plasma spectrum of the stones from inside the ureter and monitored the process of fragmentation with the laser. We have been able to identify the problems for its clinical application. We conclude that by monitoring the feedback spectrum of plasma emission, nonvisual laser lithotripsy is reliable and safe, and can be used successfully in patients with some modifications. Its development is not to replace established endoscopic lithotripsy procedures but rather as an additional armament for the urologist in special situations. Also, the technique can be further exploited for a variety of clinical uses.

Humans↗
PubMed2000

Hippocampal extracellular amino acids and EEG spectral analysis in a genetic rat model of absence epilepsy.

Absence seizures have a clearly defined thalamocortical origin. However, there is evidence from a genetic rat model of absence epilepsy, GAERS, that the underlying cellular and molecular abnormalities may also manifest themselves in other brain regions. As enhanced learning has previously been associated with this rat model, we have studied extracellular amino acid levels and EEG spectra in the hippocampus of these rats, this being a brain region associated with memory and learning. We report significantly higher levels of basal extracellular glutamate within the hippocampus of GAERS, together with transient increases in citrulline and glycine following aggravation of the absence seizures with the GABA(B) agonist, (-)baclofen. Furthermore, there is a reduction in the relative power of the EEG theta frequencies in GAERS, and a slowing of the EEG following administration of (-)baclofen which is not evident in control animals. Administration of a GABA(B) antagonist, CGP 56999, at a dose which blocks absence seizures in GAERS, caused a shift to faster frequencies of the EEG in both GAERS and control rats. It is speculated that the mechanisms underlying absence seizures in GAERS may manifest themselves in other functions modulated by thalamocortical oscillations such as cognitive processing.

Amino Acids↗
PubMed2000

Breathing frequencies of northern elephant seals at sea and on land revealed by heart rate spectral analysis.

Elephant seals breathe episodically at sea and on land and surprisingly long apnoeas occur in both situations. An important difference is that recovery from apnoeic periods is much quicker at sea, which might be due, in part, to differences in the ventilatory response. Respiratory frequencies of juvenile northern elephant seals diving at sea and resting on land were estimated from time-frequency maps of the Wigner distribution of heart rate variability. Simultaneous direct measurement of respiration and estimation of respiratory frequency (fR) in the laboratory demonstrated that the error of estimation was small (mean +/- S.D.= 1.05+/-1.23%) and was independent of the magnitude of fR. Eupnoeic fR at sea was 2.4 times higher than on land (22.0+/-2.0 vs. 9.2+/-1.3 breaths min(-1), respectively), facilitating quick recovery from the preceding dive and allowing a 34% increase in time spent apnoeic at sea versus on land. The overall fR (no. of breaths in a eupnoea divided by the total time of the apnoea+eupnoea cycle) of 2.3+/-0.6 breaths min(-1) at sea was no different from the rate on land and was inversely related to the preceding dive duration, suggesting that metabolism on longer dives may be reduced.

Animals↗