Pressure filling

Experimental Work. Few experiments measuring the blast from exploding, gas-filled pressure vessels have been reported in the open literature. One was performed by Boyer et al. (1958). They measured the overpressure produced by the burst of a small, glass sphere which was pressurized with gas. 

Baker et al. (1975) developed a method, presented below, for predicting blast effects fiom the rupture of gas-filled pressure vessels. They include a method for calculating the overpressure and impulse of blast waves from the rupture of spherical or cylindri-... 

It is not clear which measure of explosion energy is most suitable. Note that, in the method presented in Section 6.3, the energy of gas-filled pressure vessel bursts is calculated by use of Brode s formula, and for vessels filled with vapor, by use of the formula for work done in expansion. 

Blast parameters for surface bursts of gas-filled pressure vessels have not been investigated thoroughly. Parameters presently used are derived from investigations of free-air bursts. 

Dopamine is most commonly reserved for patients with low systolic blood pressures and those approaching cardiogenic shock. It may also be used in low doses (less than 3 mcg/kg per minute) to improve renal function in a patient with inadequate urine output despite high filling pressures and volume overload, although this indication is controversial. 

During IV administration, milrinone increases stroke volume (and cardiac output) with little change in heart rate. It also decreases PAOP by venodilation and thus is particularly useful in patients with a low cardiac index and an elevated LV filling pressure. However, this decrease in preload can be hazardous for patients without excessive filling pressure, leading to a decrease in cardiac index. 

Dopamine should generally be avoided in decompensated HF, but its pharmacologic actions may be preferable to dobutamine or milrinone in patients with marked systemic hypotension or cardiogenic shock in the face of elevated ventricular filling pressures, where dopamine in doses greater than 5 mcg/kg/min may be necessary to raise central aortic pressure. 

Nesiritide is manufactured using recombinant techniques and is identical to the endogenous B-type natriuretic peptide secreted by the ventricular myocardium in response to volume overload. Consequently, nesiritide mimics the vasodilatory and natriuretic actions of the endogenous peptide, resulting in venous and arterial vasodilation increases in cardiac output natriuresis and diuresis and decreased cardiac filling pressures, sympathetic nervous system activity, and renin-angiotensin-aldosterone system activity. 

Intravascular volume overload is characterized by high filling pressures (CVP greater than 12 to 15 mm Hg, PAOP greater than 20 to 24 mm Hg) and decreased CO (less than 3.5 L/min). Ifvolume overload occurs, furosemide, 20 to 40 mg, should be administered by slow IV push to produce rapid diuresis of intravascular volume and unload the heart through venous dilation. 

Dobutamine (in doses of 2 to 20 mcg/kg/min) is an a-adrenergic inotropic agent that many clinicians prefer for improving cardiac output and oxygen delivery. Dobutamine should be considered in severely septic patients with adequate filling pressures and blood pressure but low cardiac index. 

Stable angina pectoris Decreased myocardial oxygen consumption -decreased LV end-diastolic dimension -decreased LV filling pressure -decreased LV systolic pressure -decreased PVR Increased coronary blood flow -epicardial coronary artery dilation -stenotic segment dilation -coronary collateral vessel dilation -increased subendocardial perfusion... 

Systolic dysfunction Improved hemodynamic performance -decreased end-diastolic dimension -decrease filling pressure -decreased systolic pressure -decreased SVR -decreased mitral regurgitation Arterial vasodilation... 

This procedure allows filling pressure in the vehicle tank of 35 MPa to be attained even if the pressure in the low- and medium-pressure storage bank is well below this value. These data are suitable, if the temperature of the gas can be held at 15 °C. Because of the temperature increase during fast fill operation, an overpressurisation is needed to achieve the maximum fill at nominal conditions (35 MPa at 15°C). 

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