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Biomedical subjects

E R Greene

Publications and source records attributed to E R Greene.

At least 37 records · Page 2Linked to original sources
PubMed1987

Doppler predictions of pulmonary artery pressure, flow, and resistance in adults.

We examined the accuracy of noninvasive predictions of pulmonary artery pressure (P), flow (Q), and resistance (R) by means of main pulmonary artery blood velocities and diameters measured with Doppler echocardiography (DE). The ratio of noninvasive acceleration time to ejection time (An) was correlated to invasively determined mean pulmonary artery pressure (Pl) and resistance (Rl). Noninvasive flows were correlated to thermodilution flows (Ql). Simultaneous invasive and noninvasive measurements were made in nine adult patients (ages = 22 to 73 years). The results were: Pl = 87 - 152An, r = 0.90, SEE = 7 mm Hg, p less than 0.05; Rl = 899 - 1722An, r = 0.79, SEE = 121 dynes X sec X cm-5, p less than 0.05; and Ql = -0.3 + 1.21Qn, r = 0.95, SEE = 0.81 L X min-1, p less than 0.05. We then used these equations prospectively to predict Pl, Rl, and Ql in 21 of 25 (83% technically adequate) consecutive patients. Pl, Rl, and Ql ranged from 10 to 35 mm Hg, 39 to 456 dynes X sec X cm-5, and 3.51 to 8.39 L X min-1, respectively. Results were: Pl = 0.80P + 3, r = 0.72, SEE = 6 mm Hg, p less than 0.05; Rl = 0.75R - 12, r = 0.64, SEE = 77 dynes X sec X cm-5, p less than 0.005; and Ql = 0.87Q + 0.38, r = 0.83, SEE = 0.86 L X min-1, p less than 0.05. These results suggest that DE predictions of pulmonary artery pressure, flow, and resistance correlate significantly with values subsequently obtained at catheterization.

Adult↗
PubMed1987

Noninvasive Doppler assessment of human postprandial renal blood flow and cardiac output.

We compared the effects of protein, carbohydrate, or water ingestion on human renal blood flow (RBF) and cardiac output (CO). We validated and applied a noninvasive ultrasonic Doppler method to measure blood velocities and lumen diameters in the right renal artery and the ascending aorta of five healthy adults. From these measurements, we calculated the average RBF and CO over five cardiac cycles. Normalizing to body surface area, renal blood flow index to one kidney (RI) and cardiac index (CI) were calculated. The percentage of the CI distributed to a single kidney was determined as %CI = RI/CI. Subjects were studied randomly on three separate days after ingestion of each of the following equivolume (500 ml) meals: 1) 150 g protein, 30 g fat, and 30 g carbohydrate (P); 2) 150 g carbohydrate, 30 g fat, and 30 g protein (C); and 3) water. Data were obtained after 12 h of fasting and at 30, 60, 90, 120, 180, and 240 min postprandially. Analysis of covariance revealed significant (P less than 0.05) increases from fasting levels in postprandial RI at 90 to 240 min after P. Postprandial RI with P was significantly higher than with C at 180 and 240 min. Postprandial %CI with P and C decreased significantly from the fasting value at 30 to 180 min. Heart rate and mean arm cuff blood pressure did not change significantly with any diet. Results suggest that the protein-rich meal evokes a more sustained increase in postprandial RI than the carbohydrate rich meal. Despite the increase in postprandial RI, the percentage of cardiac output perfusing a kidney declines similarly with both diets.

Adult↗
PubMed1986

Aortic blood flow during sequential MAST inflation.

Cardiac output, pulse rate, blood pressure, and distal abdominal aortic blood flow were measured in ten healthy volunteers during sequential inflation of medical antishock trousers. Full inflation of all three compartments decreased distal aortic blood flow by three quarters (P less than .001) and increased blood pressure by 10% (P less than .001), but had no effect on cardiac output or pulse rate. Inflation to lower pressures was markedly less effective.

Adult↗
PubMed1986

Chronic maternal cigarette smoking and fetal abdominal aortic blood flow in humans.

The abdominal aortic blood flow was measured in 19 fetuses of nonsmoking mothers (NS) and five fetuses of smoking mothers (S) who consumed over 10 cigarettes per day throughout gestation. Serial blood flow measurements beginning in the mid-second trimester to term were made noninvasively with an ultrasonic duplex scanner. Biparietal and transverse abdominal diameters were used to estimate gestational age and fetal weight. Blood velocity spectral waveforms and lumen diameters were used to calculate blood flow (Q, ml/min) and weight normalized blood flow (Q/kg, ml/kg/min). Both Q and Q/kg for the two groups were significantly different by analysis of variance throughout the periods of observation. Third trimester Q and Q/kg (+/- SD) in the S group (738 +/- 20 ml/min and 278 +/- 36 ml/kg/min) were significantly higher (P less than 0.01) than values in the NS group (522 +/- 60 ml/min and 180 +/- 24 ml/kg/min). A redistribution of blood flow to the placenta resulting from an increase in fetal systemic vascular resistance is postulated.

Aorta, Abdominal↗
PubMed1985

Noninvasive Doppler flowmetry for measuring regional blood flow.

Ultrasonic Doppler flowmetry should assume an increasingly important role in the serial evaluation of human cardiovascular physiology. The principal advantages of this method are that it (1) is noninvasive, (2) is nontraumatic, (3) provides anatomic and physiologic data, and (4) provides dynamic measurements. Nevertheless, the equally important limitations of the technique are that it (1) is difficult to apply in some subjects (ie, those who are obese or have anatomic variations), (2) requires operator skill and a thorough knowledge of human anatomy and cardiovascular dynamics, (3) has a finite spatial resolution that may compromise the measurement of small (1 mm) vessel diameters, and (4) has a finite velocity-measuring capability that will affect measurements of blood velocities outside the range of approximately 2 to 200 cm/sec. Full appreciation of the capabilities and limitations of noninvasive ultrasonic Doppler flowmetry makes possible a better understanding of the dynamic interplay of anatomy, pressure, flow, and resistance in the normal and abnormal intact human cardiovascular system.

Adult↗
PubMed1985

Noninvasive Doppler determination of cardiac output during submaximal and peak exercise.

We compared pulsed Doppler (PD) measurements of stroke volume (SV) and cardiac output (CO) as a function of work load with previously reported values that were obtained by standard invasive methods. Suprasternal notch measurements of Doppler-shifted frequency (delta f) were obtained from the ascending aorta and SV calculated with the Doppler equation and an independent measurement of aortic diameter. Motion artifacts were minimized with the aid of a restraining table cycle ergometer. Signal aliasing was accommodated with manual summation of delta f waveforms. A total of 207 determinations were made in 10 sitting subjects exercising to exhaustion. Linear regression analysis of CO vs. work load was significant (P less than 0.001). The correlation coefficient (r = 0.95) and standard error of estimate value (1.21 1/min) were similar to values from the literature. Absolute values of CO and SV underestimated the literature values across all work loads. Technical reproducibility was assessed by comparing with paired t tests the differences between 65 duplicate serial measurements of CO and SV at rest and exercise. No significant differences (P less than 0.001) were found. We concluded that PD-determined SV and CO are reproducible and correlate linearly with work load in a manner consistent with reported invasive techniques. Thus the PD method appears suitable for use during submaximal and peak exercise.

Adult↗
PubMed1985

Serial echo-Doppler measurements of human fetal abdominal aortic blood flow.

An echo-Doppler duplex scanner (DS) was used to make serial noninvasive measurements of human fetal abdominal aortic blood flow (Q). In 18 uncomplicated pregnancies (16 weeks to term), Doppler shifted frequency spectral waveforms (delta f), Doppler incident angles (theta), and peak systolic lumen diameters (D) were measured. Using the measured values of delta f and theta, the temporal average blood velocity (V) in the cardiac cycle was calculated from the Doppler equation. Values of Q were calculated using the equation: Q = pi X (D2/2) X V X HR, where HR is the heart rate. Gestational age (GA) and fetal weight (FW) were estimated from biparietal and transverse abdominal diameters. Each fetus was studied three to eight times at 2- to 4-week intervals. Results showed that Q increased nonlinearly with GA. Normalized to estimated FW, values of Q/kg did not vary significantly with estimated GA and gave an overall mean value (+/- standard deviation) during gestation of 184 +/- 35 ml/kg/min.

Adult↗
PubMed1984

Comparison of noninvasive pulsed Doppler and Fick measurements of stroke volume in cardiac patients.

We compared simultaneous measurements of stroke volume by direct Fick (SVF) and noninvasive pulsed Doppler (SVD) techniques in 15 resting, supine cardiac patients. Doppler measurements of ascending aorta blood velocity were obtained from the suprasternal notch with a single crystal transducer. The systolic velocity integral of the spatial-average velocity waveform was multiplied by cross-sectional area from the systolic aortic diameter, obtained independently by M-mode echocardiography, to determine absolute values for SVD. The resulting linear regression equation was SVD = -1.14 + 0.95SVF, r = +0.91, p less than 0.0001. The mean SVD and SVF values were 68 and 73 cm3, respectively. These results in consecutive patients serve to validate empirically the pulsed Doppler method at rest. It is a convenient, safe, and painless procedure which appears appropriate for clinical diagnostic screening where serial measurements would be useful. However, this noninvasive technique does require technical experience and an understanding of anatomy and flow waveforms by the operator to obtain valid measurements.

Aged↗
PubMed1984

Noninvasive diagnosis of renal artery stenosis by echo-Doppler velocimetry.

We evaluated the diagnostic accuracy of ultrasonic echo-Doppler velocimetry for the noninvasive diagnosis of renal artery stenosis. Renal artery stenosis was diagnosed if one or more of the following four abnormal hemodynamic parameters were found by Doppler velocimetry: (1) peak blood velocity greater than 100 cm . sec-1 in a focal area along the length of a renal artery, (2) absence of blood velocity during diastole, (3) absence of any detectable blood velocity denoting occlusion, or (4) broad-band Doppler frequency spectra due to focal blood velocity disturbances. With these criteria, the presence or absence of renal artery stenosis was blindly evaluated in 26 patients (52 arteries) who underwent standard or digital subtraction angiography. Compared to arteriography (reduction in diameter greater than or equal to 50%), the sensitivity of Doppler method was 89%, while its specificity was 73%. This noninvasive method may be useful in selecting patients for radiographic evaluation of renal artery stenosis and in the long term follow-up of these patients. Furthermore, echo-Doppler velocimetry may have the unique capability of assessing the hemodynamic consequences of renal artery stenosis.

Angiography↗
PubMed1984

Femoral blood flow in term and premature infants.

A specially designed 20-MHz pulsed Doppler velocity meter was used to quantify noninvasively common femoral artery blood flow and blood flow characteristics in 11 normal term and 12 premature infants. Femoral artery mean velocity (vf), blood flow (Q), weight-normalized blood flow (Q/kg) and pulsatility index (PI) were determined for the two groups. Mean values for Q (+/- SD) in the term and preterm infants were 27.3 +/- 10.3 and 23.4 +/- 14.7 (ml X min-1), respectively (P less than 0.1). Mean Q/kg for the premature infants was significantly higher (22.1 +/- 12.8) than that for the term infants (9.1 +/- 4.2), P less than 0.005. This study demonstrates differences between the pulsatile blood flow and velocity characteristics of the femoral arteries of premature and of full-term infants.

Animals↗