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Head-capacity curves for 1/3 and 3 horsepower (HP) pumps. By comparing the 2 curves, the 1/3 HP pump can pump a 3 gallons per minute flow to a head of 250 feet, but to pump that flow to a head of 1200 feet requires 3 HP, 9Â the HP. Also, notice that an increase in HP shifts the curve upward and to the right. The 0.002 HP curve corresponds to Figure 6. GPM, gallons per minute. Reproduced from https://inspectapedia.com/water/WellPump Capacity.php, as visited November 30, 2018, with permission from InspectAPedia.com. Image has been provided courtesy of InspectAPedia.com. InspectAPedia.com is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public -InspectApedia.com has no business nor financial connection with any manufacturer or service provider discussed at our website.
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Background
The purpose of this article is to examine the systemic circulation and left ventricular (LV) performance by alternative, nonconventional approaches: systemic vascular conductance (GSV) and the head-capacity relation (ie, the relation between LV pressure and cardiac output), respectively; in so doing, we aspired to present a novel and imp...
Context in source publication
Context 1
... depended on the power available; a horse (providing a horsepower) could raise water faster than a person. As the industrial revolution began in the 18th century, the need to remove water from ever deeper metal and coal mines increased. Thus, there was a need for water to be pumped in greater volumes to greater heights, and more power was needed (Fig. 1). The introduction of steam engines provided the power. What then became important for pumps was their head-capacity curve, where the head is the height to which the liquid is pumped and the capacity is the flow the pump can generate against that head. The National Fire Protection Agency of the United States established the first ...
Citations
... John Tyberg's group recently proposed a novel approach which combines quantification of vascular conductance and the head-capacity curve to assess LV pump performance. 11 This method remains to be tested clinically. ...
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(A and B) Prediction of 1-year mortality by LVEF measured during rest (A) and by maximum cardiac power during dobutamine stress (B) in patients with severe acute or chronic heart failure. Means ± SD. For LVEF, there is considerable overlap, whereas maximum cardiac power differentiates well between survivors and non-survivors. An open circle indicates cardiac transplanted and open squares indicate sudden deaths. Modified from Tan.⁸ (C) Data from the SHOCK Trial Registry showing that cardiac power was a strong predictor of mortality in cardiogenic shock. Modified from Fincke et al.⁹ (D) Five-year mortality was similar in heart failure patients with preserved, borderline, and reduced ejection fraction. Modified from Shah et al.¹⁰ (E) Illustration of a patient during stress echocardiography with a semi-supine bicycle. (F) Five-year Kaplan–Meier survival curves for mortality stratified by quartiles of peak stress cardiac power/mass. Patients with the lowest cardiac power/mass in quartile 1 had the worst survival followed by quartiles 2 and 3, and was the best in quartile 4. Adjusted for age, sex, peak metabolic equivalents, diabetes mellitus, and diastolic function at baseline. Reproduced from Anand et al.¹
Graphical abstract
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(A and B) Prediction of 1-year mortality by LVEF measured during rest (A) and by maximum cardiac power during dobutamine stress (B) in patients with severe acute or chronic heart failure. Means ± SD. For LVEF, there is considerable overlap, whereas maximum cardiac power differentiates well between survivors and non-survivors. An open circle indicates cardiac transplanted and open squares indicate sudden deaths. Modified from Tan.⁸ (C) Data from the SHOCK Trial Registry showing that cardiac power was a strong predictor of mortality in cardiogenic shock. Modified from Fincke et al.⁹ (D) Five-year mortality was similar in heart failure patients with preserved, borderline, and reduced ejection fraction. Modified from Shah et al.¹⁰ (E) Illustration of a patient during stress echocardiography with a semi-supine bicycle. (F) Five-year Kaplan–Meier survival curves for mortality stratified by quartiles of peak stress cardiac power/mass. Patients with the lowest cardiac power/mass in quartile 1 had the worst survival followed by quartiles 2 and 3, and was the best in quartile 4. Adjusted for age, sex, peak metabolic equivalents, diabetes mellitus, and diastolic function at baseline. Reproduced from Anand et al.
While the effects of changing heart rate and systemic vascular resistance have been generally understood and appreciated, the effects of changes in left ventricular contractility on end-systolic volume may have been less understood and appreciated and the effects of changes in venous capacitance on end-diastolic volume may have been unknown to many readers. Herein, we have provided a brief review for the medical student and beginning graduate student highlighting these sometimes-complex relationships.
