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At least 811 records · Page 45Linked to original sources
PubMed1994

Corrected formula for estimating peripheral blood flow by impedance plethysmography.

In this paper, the limitations of the conventional formula for the computation of peripheral blood flow from impedance plethysmograms are highlighted, and a correction to the formula is suggested. A conductivity cell experiment is described to show the dependence of the value of the blood flow index (BFI), obtained from the conventional formula, on the mean resistivity of the cell. It is also shown that the value of the corrected BFI is independent of the mean resistivity. Anomalies observed in the amplitude of systolic waves in impedance plethysmograms of patients with oedema are explained.

Adult↗
PubMed1996

Digital pulse plethysmography as a non-invasive method for predicting drug-induced changes in left ventricular preload.

OBJECTIVE: Changes in the contour of the plethysmographically recorded digital pulse curve after nitrate ingestion are well known, but it has not been fully established whether these changes reflect nitrate action on left ventricular (LV) preload or afterload. Therefore, we compared the pulse wave contour after administration of equieffective doses of nitroglycerin and nifedipine. METHODS: In 20 patients with coronary artery disease we measured aortic blood pressure curve in the aorta ascendens, digital volume pulse curve with a photoelectric pulse pickup, Riva Rocci blood pressure and heart rate after administration of either 0.8 mg nitroglycerin or 10 mg nifedipine. RESULTS: Peak plasma concentrations of nitroglycerin and nifedipine were achieved 5 min and 20 min after ingestion of the drugs. Systolic aortic blood pressure decreased after both nitroglycerin and nifedipine to 19.4 mmHg, but diastolic blood pressure decreased only after nifedipine by 10.5 mmHg (P < 0.05). Riva Rocci blood pressures showed a similar time course. Heart rate increased from 67.4 to 70.9 beats.min-1 after nitroglycerin and from 58.9 to 69.4 beats.min-1 after nifedipine. The calculated a/b ratio of the aortic pressure curve increased after both medications (nitroglycerin, from 1.66 to 1.99; nifedipine, from 1.66 to 1.93) and its time course mimicked that of the systolic blood pressure. The a/b ratio of the digital pulse curve did not change after nifedipine, but showed a pronounced rise after nitroglycerin from 1.29 to 1.84. With regard to pharmacological actions, nitroglycerin causes a reduction in LV preload and afterload, whereas nifedipine has only LV-afterload-reducing activity. CONCLUSION: We conclude, that the reduction in afterload did not cause the typical changes in wave contour of the peripheral pulse curve which occur with organic nitrates. Most likely changes in the a/b ratio reflect changes in LV preload.

Adult↗
PubMed2006

Automated bedside measurement of penile blood flow using pulse-volume plethysmography.

PURPOSE: To evaluate the efficiency of the form PWV/ABI (pulse wave velocity/ankle brachial pressure index) for measuring penile blood pressure (PBP) and the penile brachial pressure index (PBI). METHODS: We measured PBP and the PBI using both form PWV/ABI and Doppler ultrasonography in 40 men with surgical disorders. RESULTS: By using pulse-volume recording, the form PWV/ABI can simultaneously measure PBP and bilateral brachial artery pressure, and calculate the PBI automatically. The data obtained showed strong correlations with those obtained by the conventional Doppler ultrasound technique. Moreover, measurements were completed within 5 min at the bedside and the data were stored in the device's memory. CONCLUSION: The form PWV/ABI is a useful tool for assessing pelvic hemodynamics and diagnosing vasculogenic impotence.

Aged↗
PubMed2006

Evaluation of cardiac monitoring using fiber optic plethysmography.

A fiber optic plethysmograph (FOP) has been redesigned and used to monitor cardiac activity in real time during apnoea. The device was tested using four healthy subjects aged between 23 and 31, and it is concluded that the device performs reliably. Advanced algorithms have been developed and implemented to perform the cardiac signal extraction. A strong correlation is noted between the signals derived using the FOP and the respiratory inductive plethysmograph (RIP) when the latter has also been applied to monitor cardiac activity. The approach developed for interpreting thoracocardiograms (TCGs) and abdominocardiograms (ACGs) derived from the RIP is therefore directly applicable to the interpretation of the corresponding FOP signals. The prospect of using the FOP system for real-time gating in a magnetic resonance (MR) scanner environment is discussed.

Adult↗