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Plethysmography
Doppler and plethysmography measure both the quantitative and qualitative flow of blood in the arteries and capillary beds. In short, they determine if you have an adequate blood flow in the area the doctor is testing. Most commonly used for disorders such as Peripheral Arterial Disease (PAD) or "Restless Leg Syndrome" the tests are both non-invasive and painless. The tests are also useful in determining whether symptoms such as pain, tingling, or numbness, have a vascular component or cause, in addition to a multitude of other causations such as a "pinched nerve" (neurological component). People are often unaware, that after a traumatic injury, such as an automobile accident, that many of their symptoms may have a vascular component, which, if left undiagnosed or untreated, will often get worse with time. Many times these people present with headaches or coldness in their hands or feet. The upper two videos show the difference between a normal plethysmography (on top) and a patient that has decreased blood flow in the feet after experiencing a motor vehicle accident five years ago and has been complaining of "coldness" and "tingling" in the feet to their primary physician for almost eighteen months before being referred to our clinic. You will notice that the wave height is smaller in the second (bottom test). Two things to note. First, the sensitivity setting (middle row of buttons) is set at 5 (blue button) in both views so as not to distort results. Second, you should notice the absence of sound in the lower test as the blood flow at the 5 sensitivity was below the threshold to trigger the audio control.
http://www.cornerstoneclinic.net/custom ... tools.htmlThis is calf plethysmography, I believe. Still interesting.
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Aust Crit Care. 2000 Mar;13(1):14-20.
Plethysmography: the new wave in haemodynamic monitoring--a review of clinical applications.
Dennis MJ.
Epworth Hospital, Richmond, Victoria.
Abstract
The plethysmograph, a useful, non-invasive circulatory assessment capability featured on most modern pulse oximeters, provides a waveform representation of pulsatile peripheral blood flow, from which can be drawn assessments of both the peripheral and central circulation. Implementation and maintenance of plethysmography monitoring is straightforward and uncomplicated by virtue of its non-invasiveness. Yet despite its capabilities, ease of use and widespread availability it remains an underutilised data source. Diagnostic and monitoring capabilities of the device include heart rate and rhythm monitoring, detection of myocardial and valvular dysfunction, assessment of intra-aortic balloon pump performance when pressure waveforms are unobtainable, detection and measurement of pulsus paradoxus, improved performance of the Allen's test and detection of peripheral vascular diseases, peripheral vasoconstriction and developing shock. This paper describes the range of established applications of plethysmography, reviews pertinent literature and describes the directions in which, in the absence of supportive literature, clinical practice is finding applications.
www.ncbi.nlm.nih.gov/pubmed/11271019Plethysmography is useful but underused.
Zamboni is brilliant.
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Int J Sports Med. 1999 Nov;20(8):555-9.
Reproducibility of resting peripheral blood flow using strain gauge plethysmography.
Fehling PC, Arciero PJ, MacPherson CJ, Smith DL.
Department of Exercise Science and Dance, Skidmore College, Saratoga Springs, NY 12866, USA.
pfehling@skidmore.eduAbstract
The purpose of this study was to examine the intra-tester and inter-tester reliability of strain gauge plethysmography (SGP) using the Hokanson EC-5R plethysmograph among three investigators. An arterial inflow test was performed by each of the investigators on fifteen college-aged volunteers at the forearm and calf sites. Intra-tester reliability was assessed by analyzing three serial measurements obtained at both sites. Intertester reliability was assessed in two ways: first, by having the three investigators obtain and analyze their own recordings, and, second, by having all three investigators (Testers 1, 2, and 3) analyze SGP recordings obtained by the most experienced investigator (Tester 1). The mean coefficient of variation (CV) for the intra-tester analysis was similar at the forearm (4.9%) and calf (4.0%) sites. The inter-tester analysis revealed that there were no significant differences among the three testers at either site when investigators obtained and analyzed their own waveforms. The CV calculated from the means of the three investigators was greater at the forearm site (10.7%) than at the calf site (2.5%). Similarly, when Testers 2 and 3 analyzed Tester 1's waveforms there were no significant differences found among testers at either site and the CV was less than when each investigator obtained his/her own waveforms. Strain gauge plethysmography blood flow measures obtained by experienced testers, under controlled laboratory conditions, are reproducible. The small variability in blood flow that exists is more attributable to variability in the acquisition of the waveforms than in the analysis of the waveforms.
The latter publication is on the reproducibility of strain gauge plethysmography measurements on the calf and forearm. It was found to have high reproducibility. I feel comfortable with the statement that the neck plethysmograph is also reproducible and relatively operator independent, in particular comparison to the doppler ultrasound.
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