Pulmonary function tests cannot predict exercise-induced hypoxemia in chronic obstructive pulmonary disease.

We studied 40 patients with chronic obstructive pulmonary disease (COPD) to determine whether measurements of pulmonary function could predict a fall in arterial oxygen pressure (PaO2) with exercise. The PaO2 fell more than 3 mm Hg in 21 patients (group 1), did not change (+/- 3 mm Hg) in nine patients (group 2), and increased more than 3 mm Hg in ten patients (group 3). Group 3 had significantly less severe expiratory obstruction than groups 1 and 2. The most significant variables in predicting a change in PaO2 with exercise were the ratio of the forced expiratory volume in one second over the forced vital capacity (FEV1/FVC) and the single-breath carbon monoxide diffusing capacity (Dsb). Measurements of FEV1/FVC of 0.50 or more and Dsb of 20 ml/min/mm Hg or more were 100 percent predictive in excluding a fall in PaO2 with exercise. Measurements below these thresholds could not be used reliably to predict which patients would develop worsening hypoxemia with exercise. Because of wide variability in reference values from eight different published studies for diffusing capacity, recommended criteria based on the percent predicted Dsb should be used with caution. We conclude that pulmonary function measurements cannot be used to predict exercise-induced hypoxemia in patients with COPD; however, the measurements may be useful in identifying patients whose condition is less severe who are unlikely to develop worsening hypoxemia with exercise.

Accuracy of two ear oximeters at rest and during exercise in pulmonary patients.

The accuracy of 2 ear oximeters (Hewlett-Packard 47201A and Biox IIA) was evaluated at rest and during exercise in 116 pulmonary patients. Ear oximetry measurements were compared with arterial oxygen saturation (SaO2) measured from simultaneous arterial blood samples. When used according to the manufacturer's instructions for stabilization during exercise testing, both oximeters demonstrated comparable accuracy in estimating arterial blood SaO2 both at rest and during exercise in these patients (95% confidence limits, 2 SEE = +/- 4 to 5%). The oximeters were more accurate in measuring a change in SaO2 from a previous reading (95% confidence limits, 2 SEE = +/- 2.5 to 3.5%). COHgb levels greater than 4% and dark skin pigmentation appeared to decrease the accuracy of ear oximetry measurements. Within the limitations of accuracy, both ear oximeters may be useful for clinical exercise testing in pulmonary patients.

Breath suspension during the transcendental meditation technique.

We observed, over four independent experiments, 565 criterion-meeting episodes of breath suspension in 40 subjects practicing the Transcendental Mediation technique (TM), a simple mental technique involving no breath control procedures. The frequency and length of these breath suspension episodes were substantially and significantly greater for TM subjects than for control subjects relaxing with eyes closed. Voluntary control of respiration was most probably eliminated as an explanation of ths phenomenon by the experimental design and by the use of a variety of nonintrusive respiration transducers, including a two-channel magnetometer, an indirect but accurate means of monitoring respiration. Many TM subjects report experience of a completely quiescent mental state characterized by maintained awareness in the absence of thought. Eleven TM subjects were instructed to press an event mark button after each episode of this pure consciousness experience. The temporal distribution of button presses was significantly related (p less than 10(-10) to the distribution of breath suspension episodes, indicating that breath suspension is a physiological correlate of some, but not all, episodes of the pure consciousness experience. In an extensive study of a single advanced mediator, pure consciousness experiences were also associated with reduced heart rate; high basal skin resistance; stable phasic skin resistance; markedly reduced mean respiration rate, mean minute ventilation and mean metabolic rate; and statistically consistent changes in EEG power and EEG coherence (an indicator of long-range spatial order in the nervous system).

The transcendental meditation technique and acute experimental pain.

The Transcendental Meditation (TM) technique decreases the distress associated with the experience of acute experimental pain. Fifteen advanced mediators and 15 controls were administered the cold pressor test before and after a 20 minute period of meditation (TM group) or relaxation (control group). Verbal reports of the intensity of pain sensation and pain distress were obtained at intervals during the cold pressor trials. Skin resistance and heart rate were measured throughout. The mean distress level for the TM group was significantly lower than controls during both trials; the mean pain sensation level for the TM group did not differ significantly from controls during either trial. Heart rate and skin resistant changed for both groups in the expected manner, with no significant differences between groups. The validity, implications, and possible causes of these results are discussed.

Specificity of the antibody receptor site to D-lysergamide: model of a physiological receptor for lysergic acid diethylamide.

Antibodies to D-lysergic acid have been produced in rabbits and guinea pigs and a radioimmunoassay for the hapten was developed. The specificity of this lysergamide-antilysergamide reaction was determined by competitive binding with unlabeled lysergic acid diethylamide (LSD), psychotomimetic drugs, neurotransmitters, and other compounds with diverse structures. LSD and several related ergot alkaloids were potent competitors, three to seven times more potent than lysergic acid itself. The N,N-dimethyl derivatives of several compounds, including tryptamine, 5-hydroxytryptamine, 4-hydroxytryptamine, 5-methoxytryptamine, tyramine, and mescaline, were only about ten times less effective than lysergic acid, even though these compounds lack some of the ring systems of lysergic acid. The pattern of inhibition by related compounds with various substituents suggests that the antibody receptor site recognizes structural features resembling the LSD molecule. In particular, the aromatic nucleus and the dimethylated ethylamine side chain in phenylethylamine and tryptamine derivatives may assume in solution a conformation resembling ring A and the methylated nitrogen in ring C of LSD. Among the tryptamine derivatives, a large percentage of the most potent competitors are also psychotomimetic compounds.