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Biomedical subjects

S Porges

Publications and source records attributed to S Porges.

4 recordsLinked to original sources
PubMed1997

Respiratory sinus arrhythmia versus neck/trapezius EMG and incentive inspirometry biofeedback for asthma: a pilot study.

This pilot study compared biofeedback to increase respiratory sinus arrhythmia (RSA) with EMG and incentive inspirometry biofeedback in asthmatic adults. A three-group design (Waiting List Control n = 5, RSA biofeedback n = 6, and EMG biofeedback n = 6) was used. Six sessions of training were given in each of the biofeedback groups. In each of three testing sessions, five min. of respiratory resistance and EKG were obtained before and after a 20-min biofeedback session. Additional five-min epochs of data were collected at the beginning and end of the biofeedback period (or, in the control group, self-relaxation). Decreases in respiratory impedance occurred only in the RSA biofeedback group. Traub-Hering-Mayer (THM) waves (.03-.12 Hz) in heart period increased significantly in amplitude during RSA biofeedback. Subjects did not report significantly more relaxation during EMG or RSA biofeedback than during the control condition. However, decreases in pulmonary impedance, across groups, were associated with increases in relaxation. The results are consistent with Vaschillo's theory that RSA biofeedback exercises homeostatic autonomic reflex mechanisms through increasing the amplitude of cardiac oscillations. However, deep breathing during RSA biofeedback is a possible alternate explanation.

Adolescent↗
PubMed1997

Relationship between changes in EMG and respiratory sinus arrhythmia in a study of relaxation therapy for asthma.

This paper reports the relationships among changes in cardiovagal activity, surface EMG, and measures of pulmonary function in a study of relaxation therapy for asthma. Changes in FEV1/FVC were negatively correlated with those in cardiac interbeat interval, consistent with the hypothesis that relaxation-induced changes in airway function are mediated autonomically, with increased vagal tone and/or decreased sympathetic arousal producing bronchoconstriction. Contrary to Kotses's theory of a vagal-trigeminal reflex as mediator for relaxation-induced improvement in asthma, decreases in pulmonary function occurred during relaxation sessions, accompanied by increases in cardiovagal activity, and within-session changes in frontal EMG in the first session of training were positively associated with changes in a measure of pulmonary function (FEV1/FVC). However, consistent with this hypothesis, first-session frontalis EMG changes were positively associated with changes in respiratory sinus arrhythmia, and last-session changes in cardiac interbeat interval were positively associated with changes in FEV1/FVC. The results suggest that the immediate effects of generalized relaxation instruction can be associated with a parasympathetic rebound, which, in tum, may induce countertherapeutic changes in asthma. However, the effects of specific facial muscle relaxation remain unclear.

Adult↗
PubMedDate not supplied

Behavioral task-induced bronchodilation in asthma during active and passive tasks: a possible cholinergic link to psychologically induced airway changes.

This study investigated pulmonary and autonomic reactions to active and passive behavioral laboratory tasks among asthmatic subjects. It also examined the relationship between airway irritability, as measured by the methacholine challenge test (MCT), and autonomic activity and reactivity to these tasks. Fifty-one asthmatic and 37 nonasthmatic subjects were exposed to psychological laboratory tasks involving either active (mental arithmetic and reaction time) or passive (films depicting shop accidents and thoracic surgery) response. The MCT was given to asthmatics in a separate session. Active tasks reduced respiratory impedance, as measured by forced oscillation pneumography. They also increased heart rate and appeared to block vagal activity, as measured by respiratory sinus arrhythmia (RSA). Airway irritability as assessed by the MCT was positively related to amplitude of RSA and to skin conductance levels. Our data suggest that active and passive behavioral tasks may produce different pulmonary effects among both asthmatic and nonasthmatic individuals. Engaging in tasks requiring active responses may produce temporary improvements in pulmonary function. No autonomic differences were obtained between asthmatics and nonasthmatics in physiological response to stress, but greater cholinergic receptor sensitivity was suggested among high responders to methacholine.

Adolescent↗