Comparison of impedance cardiographic measurements using band and spot electrodes.
ABSTRACT The comprehensive assessment of cardiac function using impedance cardiography has led to increasingly widespread use of the technique in psychophysiology. Disposable adhesive band electrodes have been the most widely used electrode type, but spot electrode configurations present attractive alternatives in terms of convenience and subject comfort. The present study was designed to evaluate whether one such spot electrode configuration yielded the same information as the more standard band electrodes for cardiac output and systolic time interval measurement. Male and female healthy adult subjects (N = 20) were tested. Comparisons between spot and band electrodes were made for the absolute magnitude of cardiac output and systolic time intervals, as well as for responses to the highly reproducible effects of bicycle exercise. Consistent with previous findings, systolic time interval measurements were unaffected by electrode type. However, for cardiac output measurements, differences between spot and band electrode measurements were found. Under resting conditions, the absolute magnitudes of cardiac output values measured using spot electrodes were smaller than for band electrodes. Subtle, yet significant differences were also found for cardiac output responses to exercise, with spot electrodes indicating greater increases in cardiac output than band electrodes. At the same time, anticipated gender differences found for cardiac output at rest and in response to exercise were unaffected by electrode type. Overall, these findings suggest that when comparing the results of studies that have utilized different impedance electrode types, it would be prudent to remain alert to the possibility of confounding influences.
- SourceAvailable from: Ruth Elaine GravesSchizophrenia Research 04/2011; 130:271-276. DOI:10.1016/j.schres.2010.02.1001 · 4.43 Impact Factor
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ABSTRACT: Relative to watching in a natural manner, people asked to suppress or exaggerate their facial response to a negative emotional stimulus experience greater activation of the sympathetic nervous system but report a similar subjective emotional experience. The present research extends prior research on response modulation in two important ways. First, discrete indicators of cardiac vagal and sympathetic control (respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP), respectively) were included as dependent measures along with interbeat interval (IBI) and skin conductance (EDR). Second, to help generalize results across response-focused modulation techniques, participants suppressed, exaggerated, or exerted no control over their responses while watching a disgust-eliciting film (for control purposes, a fourth group was asked to watch a neutral film naturally). Response modulation was associated with significantly decreased PEP (increased cardiac sympathetic control) relative to those in the natural-watch conditions. All participants evidenced increased EDR while watching the disgusting clip, but facial modulation did not produce EDR reactivity beyond that of watching the disgusting film naturally. Exaggerators experienced decreased IBI during modulation (perhaps due to increased muscle contraction) whereas all other groups showed increased IBI (i.e., the orienting response). Neither emotional experience nor facial modulation reliably impacted RSA, respiration rate, or inspiratory depth.Biological Psychology 02/2006; 71(1):90-9. DOI:10.1016/j.biopsycho.2005.02.006 · 3.47 Impact Factor
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ABSTRACT: Secretory immunoglobulin A (sIgA) in saliva and cardiovascular activity were measured at rest and during mental arithmetic. Task difficulty was manipulated by presenting easy, hard, and impossible versions of the mental arithmetic task in counterbalanced order, while task novelty was operationalised as order of presentation (i.e. first, second, third). Mental arithmetic elicited significant increases in sIgA concentration and sIgA secretion rate, as well as significant cardiovascular effects. Performance decreased and rated difficulty increased with increasing task difficulty. However, sIgA and cardiovascular activity, with the exception of diastolic blood pressure, were insensitive to variations in task difficulty. In contrast, sIgA concentration and a broad range of cardiovascular variables were influenced by task novelty, with more pronounced activity characterising the task version presented first, irrespective of its level of difficulty. Task novelty would seem to be a more important determinant of sIgA and cardiovascular activity than task difficulty.Biological Psychology 04/2000; 52(2):127-41. DOI:10.1016/S0301-0511(99)00028-9 · 3.47 Impact Factor