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At least 775 records · Page 43Linked to original sources
PubMed1983

Cardiovascular effects of smoking cigarettes with different nicotine deliveries. A study using multilead plethysmography.

The purpose of this investigation was to assess the impact of smoking cigarettes with different nicotine deliveries on the subcutaneous blood vessels at different sites of the body. Individual puffing behavior, estimated mouth intake of nicotine, and some personality traits were taken into account. Each of 15 female smokers was presented with four different smoking conditions in order to vary the nicotine uptake. Heart rate and five photoplethysmographic recordings were taken simultaneously and continuously. The heart rate increases were dependent on the individual mouth intake of nicotine. The smoking-induced decreases in the pulse amplitudes failed to show a significant dependency on the nicotine dose. However, the vasoconstrictive response to nicotine was considerable with the finger recordings, modest with the foot recordings, and absent with the forehead and the ear recordings. Furthermore, the magnitude of this vascular response at the finger correlated positively with personality traits of neuroticism, suggesting an explanation for the poor correlations with the dose of nicotine.

Adult↗
PubMed1985

Beta-adrenoceptor subtype of the venous capacity system: characterization by venous occlusion plethysmography.

In order to characterize the beta-adrenoceptor subtype of the venous vessel wall, venous occlusion plethysmograph studies were carried out in 7 healthy volunteers. Venous distensibility (VD) was considered to be a measure of venous tone. Infusion of the beta 1- and beta 2-adrenoceptor agonist isoproterenol (I), of the predominantly beta 2-adrenoceptor agonist fenoterol (F) and of the predominantly beta 1-adrenoceptor agonist dobutamine (D) in increasing doses led to a significant increase in VD by I and F but not by D. Administration of the beta 1-adrenoceptor antagonists betaxolol (B) and metoprolol (M) did not significantly change VD. Neither beta-adrenoceptor antagonist prevented the increase in VD provoked by subsequent administration of I or F. It is concluded that beta-adrenoceptors in the venous vessel wall belong to the beta 2-adrenoceptor subtype.

Adrenergic beta-Agonists↗
PubMed1984

Measurement of systolic time intervals during exercise using inductive plethysmography.

Measurement of systolic time intervals (STI) provides a noninvasive assessment of cardiac function in resting subjects. However, large motion artifacts often limit their application during exercise. To improve such measurements, we employed a new lightweight carotid arterial pulse transducer and minimized the artifacts by computerized signal averaging. The carotid pulse was recorded with an inductive plethysmographic transducer band (CIP) wrapped around the neck. STI derived from these measurements were compared to standard measurements from a funnel-shaped cup attached to the neck and connected to a pressure transducer (CUP) in 12 normal subjects at rest and with graded bicycle ergometry. To compare the techniques, CIP and CUP signals, together with the EKG and phonocardiogram, were connected separately to two microcomputer systems. The systems were triggered from the EKG and averaged the signals over 16 or 32 heart beats. Semi-automatic analysis of the averaged signals provided estimates of left ventricular ejection time (LVET), pre-ejection period (PEP) and electromechanical systole (QS2). Motion artifact levels of the unprocessed signals were similar with both CIP and CUP methods but were greatly reduced by signal averaging. All LVET values using CIP fell within 10% of CUP values. 85% of PEP values using CIP were within 20% of CUP values. Increasing exercise loads produced appropriate decreases in QS2, LVET, PEP and PEP/LVET consistent with increased myocardial contractility. The CIP proved comfortable to wear and did not require critical positioning as did the CUP. Measurement of STI complements exercise pulmonary testing with useful information of cardiac function.

Adult↗
PubMed1992

Characterization of aeroallergen-induced dyspnea in unrestrained guinea pigs by bias-flow-ventilated whole body plethysmography.

Aeroallergen-induced dyspnea in guinea pigs was associated with an increase in amplitude in the box pressure fluctuations (212%) and pseudo-flow signal (604%) and an 80% decline (from 0.19 to 0.04 s) in relaxation time (the time it takes the box pressure signal to drop from its peak to 1/3 of its peak value). All of these lung dysfunction changes were highly significant (P < 0.001). Pyrilamine (1 mg/kg, p.o., -2 h) inhibited dyspnea (delta P and delta F) by 50-53%. This technique allows quantitative analysis of allergic dyspnea in conscious, unrestrained guinea pigs.

Aerosols↗
PubMed1985

Comparative plethysmography; evidence for a hydrostatic effect on foot blood flow.

Blood flow in the right foot of 11 subjects was measured simultaneously by a strain gauge placed around the mid metatarsal circumference of the foot and a water displacement plethysmograph in which the foot was resting. A close linear correlation (r = 0.88) between the results of the two methods existed over a wide range of blood flows. It was apparent however that blood flow at the mid metatarsal region of the foot was only about 30% of the total foot blood flow measured by the plethysmograph. The likely cause of this finding is the varying proportion of bone to soft tissue along the length of the foot. It was observed that the strain gauge estimates of blood flow increased two to three fold when the plethysmograph was emptied, an effect that was abolished by refilling the plethysmograph. These changes were highly statistically significant (P less than 0.01) in all ten subjects in whom this comparison was made. The application of progressively increasing hydrostatic pressure in a further 4 subjects demonstrated that the reduction in blood flow was proportional to the pressure applied. Explanations for this effect based upon small temperature and pressure changes altering strain gauge performance are excluded. Three mechanisms are proposed, based upon an increase in venous leakage, a reduction in arterial inflow and the consequence of increased capillary filling occurring as a result of hydrostatic pressure within the plethysmograph.

Adolescent↗