Standard ambulatory night sleep electroencephalograph (EEG) of 11 long-term practitioners of the Transcendental Meditation (TM) program reporting "higher states of consciousness" during sleep (the experimental group) was compared to that of nine short-term practitioners and 11 non-practitioners. EEG tracings during stages 3 and 4 sleep showed the experimental group to have: 1) theta-alpha activity simultaneously with delta activity and 2) decreased chin electromyograph (EMG) during deep sleep (p = 0.002) compared to short-term practitioners. Spectral analysis fast Fourier transform (FFT) data of the first three cycles showed that: 3) the experimental subjects had significantly greater theta 2 (6-8 Hz)-alpha 1 (8-10 Hz) relative power during stages 3 and 4 than the combined control groups [t(30) = 5.5, p = 0.0000008] with no difference in time in delta; 4) there was a graded difference across groups during stages 3 and 4 in theta 2-alpha 1 power, with experimentals having greater power than short-term practitioners, who in turn had greater power than non-practitioners [t(30) = 5.08, p = 0.00002]; and 5) experimentals also had increased rapid eye movement (REM) density during REM periods compared to short-term practitioners (p = 0.04). Previous studies have found increased theta-alpha EEG activity during reported periods of "transcendental consciousness" during the TM technique. In the Vedic tradition, as described by Maharishi Mahesh Yogi, transcendental consciousness is the first of a sequence of higher states. The maintenance of transcendental consciousness along with deep sleep is said to be a distinctive criterion of further, stabilized higher states of consciousness. The findings of this study are interpreted as physiological support for this model.

A study was conducted using the Sheffield electrical impedance tomography (EIT) portable system DAS-01 P to determine the change in the cardiac image with electrode position, lung volume and body position. Sixteen electrodes were positioned in three transverse planes around the thorax at the level of the second intercostal space, at the level of the xiphisternal joint, and midway between upper and lower locations. Data were collected at each electrode level with the breath held at end expiration and after inspiring 0.5, 1 and 1.5 l of air with the subject in both the supine and sitting position. These data were analysed using a Matlab developed program that calculates the average resistivity change in the cardiac region from automatically determined borders. Results show significant individual variability with electrode position and air volume. The middle electrode most consistently shows an increase in impedance in the region of the heart during systole. In some subjects the change in the ventricular-volume-like curve showed a greater than 50% change as a function of lung volume. The pattern of variability with electrode position was not consistent among subjects. In one subject MRI images were obtained to compare actual structures with those seen in the EIT image. The results suggest that using these electrode locations reliable and consistent data, which could be used in clinical applications, cannot be obtained.

No abstract

Voluntary cardio-respiratory synchronization (VCRS) was used to investigate heart rate and blood pressure changes in the supine position in 21 subjects. VCRS involves a breathing pattern that is synchronized with the cardiac cycle. The signals to inhale and exhale are derived from the ECG. In this study, the subjects inspired for four heart beats and expired for four heart beats for 35 cycles. This technique is designed to have the heart beat occur at exactly the same phase in the respiratory cycle and lends itself to the study of the influence of the respiration cycle on heart rate and blood pressure changes. The heart rate and blood pressure changed simultaneously in the same direction, with the largest significant positive change occurring on the second heart beat during inspiration. The authors discuss the potential of VCRS for research, and clinical applications as a respiration modulator for hypertension therapy or increased heart rate variability.

Abstract-Voluntary cardio-respiratory synchronization (VCRS) is a technique where an individual's breathing is voluntarily phase locked with his/her heart beat. A signal is generated (tone or light) from the ECG that is used to pace the breath with a fixed number of heart beats for inspiration and expiration. A small portable device was developed that can create a tone to pace the breathing and record the data for repeated measurements for extended periods of time (days or weeks). The device was tested on an individual over a four-week period. Measurements of heart rate variability were made at various times throughout the day for a total of 68 recordings. The data were analyzed to separate out respiratory and non-respiratory induced changes in the heart rate using a unique time domain analysis. The results showed significant variability over the measurement period. Keywords -heart rate variability, VCRS, breathing I. INTRODUCTIONIt is well know that respiration is one of the strong contributors to heart rate variability. Under normal respiration, the breathing is not locked in time with the cardiac contraction. Therefore, the respiratory induced cardiac variations are non-stationary, and have a significantly different influence depending on when in the cardiac cycle respiration starts [1]. To improve stationarity, voluntary cardio-respiratory synchronization (VCRS) was developed [2]. The subject breathes in a normal manner but the breathing is synchronized with the heartbeat, using a signal in a predetermined ratio of the number of heartbeats for inspiration and expiration. An example of this is shown in Figure 1 for a 10 beat cycle. For the first four heart beats a tone comes on indicating to the subject to inspire. For the next six heart beats the tone is off indicating to the subject to expire. ECG Respiration Signal (Tone or Light) Inspiration ExpirationHeart beat number 0 1 2 3 4 5 6 7 8 9 10Fig. 1. Example of respiratory signal generated for a 10 heart beat cycle (four beats inspiration -six beats expiration).This technique has been used to study heart rate variability as a function of age [2,3], body position [3] and cardiotoxicity caused by chemotherapy [4]. Also, it has been used to reduce respiratory variations in cardiac impedance signals [5].The purpose of the research was to develop and test a small portable device for the study of heart rate variability and R wave to pulse interval as a function of time over a period of many weeks. II. METHODOLOGYIn order to record data repeatedly over many days a small portable device (11 x 6 x 2 cm) was designed, which is referred to as the SynchroMax. It was developed around a PIC microprocessor with memory (64K) capable of holding 32,000 beats. It can be programmed for various numbers of beats for inspiration and expiration. It was designed to measure the time interval between the R waves of the ECG (RR) and the R wave to a peripheral pulse (RP) detected with a photo-sensor. The RP interval represents the pre-ejection period plus the pulse wave velocity. The s...