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Video transcript

in order to diagnose and treat shock what do you have to do it how do you go about diagnosing and discovering shock figuring out what type of shock it is and utilizing the proper treatment for that type of shock well there's really three ways that I like to break it down so first of all what's going on in shock well we have severely decreased tissue perfusion what that means is decreased oxygenation to the different cells of the body and as we know decreased oxygenation means decreased ability to create energy and without energy cells can become defunct or die so that just of course highlights why diagnosing shock is so important so I'm going to break it down into three steps but let's think about this first of all shock is decreased tissue perfusion and so we need to focus on the delivery of oxygen well how does the body deliver oxygen well the heart pumps blood throughout the body to the tissues and so really here's an oversimplified version of how the cardiovascular system works right blood is pumped from the heart to the tissues and blood returns to the heart as and this is the cycle of oxygen delivery so looking at this the first thing I think is what can get this to fail well first of all we can mess with the pump right is there something wrong with the pump is the heart not working also along those same lines the entire cardiovascular system is there something wrong with the pipes are the blood vessels not performing their task of carrying oxygen to the tissues and back to the heart so really the first way to measure that the first way to look at that is to look at blood pressure and that's tied directly to both the pipes and the pump right blood pressure the equation for blood pressure is cardiac output times systemic vascular resistance so that's both the heart the pump and the vascular system the pipes and this is usually the way that practitioners are alerted that patients might be experiencing shock of some sort now how else can we analyze the pump now heart cells have an enzyme called troponin so when these heart cells are damaged they release troponin into the system and it can be detected in the blood so getting a blood test for troponin one way to assess the pump getting an echocardiogram is another great way to assess the pump to look directly at how the heart is functioning and contracting if it's not contracting properly blood can't be squeezed forward to the body so blood pressure troponin zecco next a really good test that is sometimes use is pulmonary capillary wedge pressure P C WP pulmonary capillary wedge pressure or also assessing CVP central venous pressure now what are these abbreviations this is a little confusing well essentially these two pressures are the different pressures in the sides of the heart pulmonary capillary wedge pressure is associated with the left side of the heart specifically the left atrium the central venous pressure is the pressure that's seen in the right atrium and so these two pressures give you an idea of how the left and the right side of the heart are functioning for example if the left side of the heart is not pumping let's say all of this tissue down here gets damaged because the patient has a heart attack right this heart tissue is dying or has died so now this heart tissue cannot squeeze it can't function this makes blood accumulate in the left ventricle it just kind of pools there because the heart can't squeeze hard enough to push it out and so pressures in the left side of the heart will be higher because this volume backs up and causes pressure on the heart but now these are both found by getting a pulmonary artery catheter and threading that catheter into the heart into the right side of the heart and then up through the pulmonary artery deep into the pulmonary vasculature in fact so deep you essentially get a wedge pressure you're wedging this probe into the pulmonary capillaries so pulmonary capillary wedge pressure you wedge this probe all the way up to determine that pressure and that gives you a good indication of the left heart pressures CVP central venous pressure here is the central vein so there's actually another part of the catheter the pulmonary artery catheter that has a probe that senses the pressure in the right side of the heart so using a pulmonary artery catheter you can get an indication of the different pressures of the heart and as I said this can help you figure out what's going on and can help you distinguish the type of shock for example if the heart is not functioning like in cardiogenic shock then you're going to have high pulmonary capillary wedge pressure 'he's right the heart is no longer functioning and can't pump blood forward however in an example like hypovolemic shock meaning low blood volume the pressures won't be very high in the heart at all there's so low blood volume that pressure is relatively low in the heart so pulmonary capillary wedge pressure may be very low and so this is just an example of how you can distinguish between types of shock okay so we've looked at the pumps in the pipes what else is important in shock so the second thing I think about is oxygen oxygen is kind of a big thing it's what we need to survive so it's the patient getting oxygen so probably the least invasive way to assess oxygen is through pulse oximetry pulse oximetry often known as pulse ox uses different wavelengths of hemoglobin to assess the oxygen status so really what you should know is that you put a little device on the finger of a patient it shines light through the arteries and has a way to calculate how many hemoglobin molecules are oxygenated versus deoxygenated so it's a quick way to assess oxygen now a little more invasive and probably one of the most important tests to get in a patient with shock is an ABG this is an arterial blood gas arterial blood gases assess several different parameters of course it will assess the oxygen in the body but it will also assess blood gases such as carbon dioxide and bicarbonate an arterial blood gas also gives you the pH or how acidic the patient's blood is these are very critical readings that are important to diagnose shock so assessing oxygen we have pulse ox and ABG getting that blood test and also your pulmonary artery catheter can get something called the central venous oxygen saturation SCV o2 so the cv is central venous oxygen saturation of the central vein now we talked about the central vein before that was the superior vena cava and the inferior vena cava which dumped blood into the right side of the heart so look at this device here the pulmonary artery catheter would actually sit inside the heart so there can be another part of this probe that assesses the oxygen content now why is that important well in different types of shock the central venous oxygen saturation can be either increased or decreased if the issue is cardiogenic shock just as an example when blood is pumped to the cells it's pumped very slowly and the cells they require the same amount of oxygen they have before but now oxygen is getting there more slowly and so the tissues furiously try to pick up more oxygen and not as much oxygen returns to the heart and that's assessed by the pulmonary artery catheter so less oxygen content means that tissues were pulling out more oxygen and in the same token if there is less oxygen extraction so for example if the tissues are flooded with fluid and there's a lot of edema oxygen cannot get to the tissues and so maybe more oxygen is carried back to the heart and so that leads to an increased central venous oxygen saturation so first look at the pump in the pipes second is the body getting oxygen and last of all if the body isn't getting oxygen is it getting damaged are the cells of the body and the organs getting damaged because they don't have oxygen right they need oxygen to create energy and without energy cells can't function so without oxygen cells can't function well I should say they can't function in the long term without oxygen in the absence of oxygen cells of the body kick up what's known as an aerobic metabolism metabolism without oxygen creating energy without oxygen the body can't sustain this for very long now the reason I mention this is a byproduct is lactic acid this is not the most efficient process so in assessing if a patient has shock is there any lactic acid that is accumulating in the body because this should not be present in high amounts under normal circumstances that's a sign of shock and that's probably you know but mean the ABG and this these are probably the most important tests to get so what else organs can be damaged what if the livers damaged if liver cells are damaged they release enzymes just like the heart did when the heart was damaged they have a specific name by it this is the test you perform to assess the livers function the liver function tests are important now how about the kidneys the kidneys can also be damaged and if they're damaged there's two things you can really look at the first if you do a blood test you can get an elevated creatinine now creatinine itself unlike lfts and troponin are not produced by the kidney but the kidneys job is to filter out fluid right if the kidneys are no longer producing fluid then creatinine accumulates in the body so that's actually creatinine comes from the muscle so it's a good marker to use if the kidneys stopped working and similarly if you see decreased urine output that means the kidneys aren't producing urine so that's a sign that the kidneys have also started to get damaged or shut down and there's lots of other ways you can assess how the organs are functioning for example the brain if a patient has confusion then that could be a sign that their brain is starting to lose its oxygen supply and last of all treatment focuses on two things and I like to say the first thing is you want to prime the pump by priming the pump I mean we want to get the pump going we need to put fluid into the heart to allow fluid to be pumped through this is exactly what happens in a water pump water needs to be in the pump to allow a pressure within the pump to push fluid forward that's exactly how our heart works there needs to be fluid in the heart to push forward so giving fluids may be a way to treat that and number two tightening the blood vessels increasing the resistance right we go back up here we see systemic vascular resistance is a part of blood pressure and the blood vessels are tightened by medications such as pressors medications that help improve resistance and improve blood pressure and so by giving fluid you're trying to establish pre-load trying to fill the heart up so it can pump and pressors you're trying to improve the vascular resistance systemic vascular resistance