Bernoulli's Equation and the conservation of energy for fluids http://plasmapheresis.net/tag/machine/ Bernoulli's Equation states: http://colgatephys111.blogspot.com/2015/12/physics-of-intravenous-drips.html Putting Bernoulli's equation into context: Equation created by myself in MSWord.    The Bernoulli's equation is used in this IV example to help us understand that the height of the IV bag has a direct relationship on the pressure differences in the fluid inside the IV bag and the fluid (blood) inside the vein at the IV site. Breaking down the equation we get the following: Piv static pressure of the IV 760 mmHg ρ= density of the IV fluid 1gm/cm3= 1000kg/m3 viv velocity of fluid moving out of the IV bag is negligible 0 yiv This is what we want to find ? Pvein Pressure inside the vein. We will use a hypothetical value 10 mmHg = 1333.22 Pa or 1333.22 N/m2 or 1333.22 kg∙m/s2 Vvein velocity of IV fluid entering the vein is negligible 0 g acceleration due to gravity 9.8 m/s2 yvein height of IV site is set to zero 0 The IV solution needs to have some pressure (Piv) higher than that of the vein (Piv + 760 mmHg). Y is the height the IV bag is above the IV site. Rearranging the equation you get ρgyiv=Pvein - Piv (the change in height between the IV sight and the IV bag). Change in Pressure = the pressure at the IV site (10m mHg+760 mmHg ) minus pressure at the IV bag (760 mmHg) = 10 mmHg. Solve for yiv to find the necessary high of our IV solution: Equation created by myself in MSWord If you prefer to see this in video form, click here. We solved the height requirement for the IV solution in order to overcome the pressure inside the vein at the IV site. Now let's analyze this. Does this make sense? Yes! The pressure inside the vein is relatively low compared to the 760 mmHg of the atmosphere, so the bag doesn't have to be that much higher than the vein. Here is a great graph showing the relationship between the vein pressure and the IV fluid pressure: Previous·Home·Next