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Current time:0:00Total duration:8:19

Video transcript

so here I have outlined the just a general concept of the cardiovascular system we have the heart over here the arteries deliver blood to the organs and the veins deliver blood back from the organs to the heart so the reason I'm going to draw this is because the cardiovascular system is critically affected in neurogenic shock now what is neurogenic shock neurogenic shock occurs when the nervous system is no longer functioning properly and this can happen from a number of things sometimes and actually most frequently it's from trauma so if a patient has something occur to their spinal cord where it's severed or an epidural goes wrong and some nerves are damaged that can lead to neurogenic shock if it's severe enough now what neurogenic shock essentially is is loss of vascular tone and pooling of peripheral blood so the nervous system provides tone to the blood vessels and also to the heart and this tone is is known as sympathetic tone it's kind of like muscles you know if you think about somebody who's flexing versus not flexing of course there's a certain tightness that the muscles undergo when you flex now that's really happening to the blood vessels at all times and it's done to really maintain blood pressure blood vessels are somewhat tightened in and squeeze down a little bit to allow blood to flow through the idea is as blood flows through the vascular system it's going to be maintained in a four direction by the blood vessels because if it hits up against the wall the blood vessel bounces it back and pushes the blood forward if it didn't do this if there was no vascular tone blood would run up against the wall and lose a lot of its energy would be really dampened so it's kind of like a trampoline you know when you're bouncing on a trampoline if the trampoline is taut enough you'll be able to bounce up and down really easily right however if you if you think about loosening the trampoline if you loosen the material on the trampoline you won't be able to bounce as high and so that's the same thing that happens here when you loosen the blood vessel it won't be able to bounce blood forward as well so like I said the nervous system provides this tone this vascular tone to both the arteries and the veins so now what happens if we shut down this nervous system well the blood vessels will lose their tightness both the arteries and the veins so I'm going to go ahead and erase this to show that the blood vessels kind of become floppy and I'm going to really exaggerate this by making them really wide so both the arteries and the veins become very floppy so you can see if this happens in the arteries Bloods not really going to make it to the organs as well right it's supposed to bounce off and bounce forward but that's not really happening anymore so it just kind of slowly makes it to the organs so you have shock you have decreased oxygen delivery decreased tissue perfusion to the organs and then blood of course trying to flow back to the heart won't be able to it'll just kind of pool it'll just stay in the venous system and only a minimum amount will return to the heart so this will actually affect the cardiac output of the heart remember blood pressure and tissue perfusion are related to cardiac output and vascular resistance systemic vascular resistance so up here in the arteries we've already shown that this systemic vascular resistance is decreased so that's going to lead to a decrease in blood pressure and tissue perfusion so let me let me actually go and write that out blood pressure and OH - delivery tissue perfusion is oxygen delivery so both of these will go down because resistance in the arteries are going down and now also the veins aren't able to deliver blood back to the heart and if we recall you can recall cardiac output is stroke volume times heart rate so if we decrease the amount of blood going back to the heart that means there's going to be less blood that the heart can squeeze forward so that means less drop volume right decreased delivery of blood to the heart leads to decreased stroke volume which means decreased cardiac output and that further worsens blood pressure and further worsens oxygen delivery you're shutting down the cardiovascular system by not being able to maintain vascular tone something else that you see it in neurogenic shock is you know the nervous system the sympathetic nervous system controls the heart rate now if you no longer have the input of the nervous system the heart rate is going to drop and so we go back to our equation heart rate drops cardiac output drops even further and blood pressure will drop and then oxygen delivery will also drop so this is truly shock tissue perfusion is just completely demolished and so is blood pressure so the entire cardiovascular system is just not able to maintain blood flow and that leads to a shutdown of oxygen delivery and so let me go ahead and scroll down so we can think about some of the symptoms I'm going to keep this somewhat in view so you can still ponder it and think about it but the symptoms of neurogenic shock will be those of decreased oxygen delivery such as altered Mental Status you know decreased urine output you think about anything that needs oxygen any organ that needs oxygen and think about what would happen if it wasn't getting oxygen it would start to shut down so organ dysfunction can occur organ dysfunction and a major symptom that you see specific to neurogenic shock is bradycardia now this is something that you should really be thinking about this is really the only shock that has bradycardia remember all the other shocks are going to try to increase heart rate speed it up to try to deliver oxygen and deliver blood to the body but here we have the heart rate dropping because it's no longer getting input from the nervous system and so we have a low heart rate bradycardia so this is a key symptom of neurogenic shock another main symptom that I want to touch on is warm skin warm skin occurs because of the dilation of all blood vessels so these blood vessels in the skin will dilate well you know they will enlarge like we were showing up here so blood can flow through the skin more easily and that's a problem because it diverts blood away from vital organs such as the brain the lungs in the heart and so the treatment of neurogenic shock will focus on trying to maintain this blood pressure so you'll give medication known as pressors pressors allow the blood vessels to clamp back down if you clamp the vessels down it directly is affecting the issue in neurogenic shock and you'll also give a lot of IV fluids to try to maintain the fluid volume right if you increase the amount of fluid in the vasculature it's more likely that you'll be able to push it forward and deliver blood to the system so IV fluid and pressors help maintain the blood pressure and a final medication that you'll see is atropine atropine works by blocking the parasympathetic nervous system so it's like stopping the rest and relaxation part of the nervous system and increases the fight-or-flight so increasing the fight-or-flight response will increase the heart rate so giving atropine will help raise up the heart rate to increase cardiac output and to improve the pumping of blood throughout the cardiovascular system