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Hypertensive crisis

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Tanner Marshall.

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Video transcript

- [Voiceover] Usually if you have hypertension, your blood pressure gets higher and higher over the course of several years even. And this slow rise also slowly causes complications. But because it's happening so slowly, there usually aren't any symptoms directly caused by high blood pressure. It is possible though that your blood pressure could rise quickly and severely enough to be what we call a hypertensive crisis. And actually there are essentially two categories of hypertensive crises. And the first is hypertensive urgency, and the other is hypertensive emergency. Let's just go over urgency first. So this hypertensive urgency is defined as the situation where your blood pressure is super elevated, but there's no acute or sudden damage to any of your target organs like your kidneys, your heart, or your brain. How high are we talkin' though? Well in general, it'd be above about 180 millimeters of mercury on the systolic side or above about 110 millimeters of mercury on the diastolic side. So it's like the blood pressure goes up super high and really fast, but none of those target organs get hit, right. But even though these organs aren't damaged, there can be symptoms associated with hypertensive urgency like a severe headache or shortness of breath, nosebleeds, and severe anxiety. This type of crisis, though, can usually be managed using some type of oral antihypertensive medication in an outpatient or a same day sort of observational setting. So urgency means no damage, right. We can probably take a guess as to what hypertensive emergency is then, huh. An emergency is when blood pressure is so high that it's reached levels that damage target organs. Sometimes this is also referred to as malignant hypertension. During one of these hypertensive emergencies, systolic blood pressure might increase above 180 millimeters of mercury, while diastolic might be above 120 millimeters of mercury, but it can also happen at lower pressures in patients whose bodies maybe aren't as used to higher blood pressures. Because target organs can be damaged, the consequences of hypertensive emergency are very, very serious and can have severe and permanent effects on the brain, heart, and kidneys. Some signs and symptoms of these emergencies can include chest pain, shortness of breath, back pain, numbness and weakness, change in vision, and difficulty speaking. One example of a serious complication that can happen to your head and your brain is called encephalopathy, where enceph means brain and pathy means disease. And this is when during a hypertensive emergency, your extremely high arterial pressure causes your cerebral arterials, which are like these small arteries in your brain, to lose their ability to regulate blood flow in the cerebral capillaries, which are even smaller blood vessels in your brain. As pressure goes up and up, fluid or blood essentially leaks out into the interstitial space causing cerebral edema or fluid buildup, which also causes an increased pressure in the skull and eventually brain dysfunction. Due to the severity of encephalopathy and other target organ complications, speedy treatment is extremely important, so much so that IV or intravenous medications are used instead of oral medications, basically to get the drugs into the bloodstream and working as quickly as possible. An IV vasodilators, IV calcium channel blocker, or IV beta blocker might be given. Each of these helps the arteries and the arterials relax. Whichever one is used, the goal is always the same: to safely reduce the blood pressure before the pressure causes serious and irreversible damage to a target organ. Since hypertensive emergency tends to be quite a bit more serious than hypertensive urgency, it's usually gonna be managed in an intensive care unit or other closely-monitored setting.