Hypertensive emergencies refer to any stage in the development of hypertension and other disease emergencies when a serious life-threatening increase in blood pressure can occur and requires emergency management. A hypertensive emergency is a severe increase in blood pressure over a short period of time (hours or days), with diastolic blood pressure greater than 130 mmHg and/or systolic blood pressure greater than 200 mmHg, accompanied by severe dysfunction or irreversible damage to vital organ tissues such as the heart, brain, kidneys, fundus, and aorta.
Or although the blood pressure is moderately elevated, it is complicated by acute left heart failure, aortic coarctation aneurysm, acute myocardial infarction or acute cerebrovascular disease, all of which are hypertensive emergencies and can be life-threatening if not rescued in time.
Timely management of hypertensive emergencies is important to bring about remission in a short period of time, prevent progressive or irreversible target organ damage, and reduce mortality. Depending on the urgency of antihypertensive treatment, there are two categories: urgent and sub-urgent. The former requires rapid reduction of blood pressure within minutes to an hour and is administered by the intravenous route; the latter requires reduction of blood pressure within a few hours to 24 hours and can use fast-acting oral antihypertensive drugs.
A. Hypertensive emergencies are commonly
1, hypertensive crisis: due to the sudden occurrence of temporary strong spasm of small arteries throughout the body, so that the blood pressure increases dramatically, especially the systolic blood pressure increases, can exceed 26.7 kPa (200 mm Hg). Pale or flushed face, irritability, palpitations, sweating, nausea, vomiting, hand and foot shaking, and angina pectoris, acute left heart failure, etc. may occur.
2, hypertensive encephalopathy: due to continuous spasm of small arteries throughout the body, especially in the brain, resulting in acute cerebral circulatory disorders, causing cerebral edema and the manifestation of increased intracranial pressure. The blood pressure increases sharply, especially the diastolic pressure, which can exceed 16.0 kPa (120 mmHg), headache, vomiting, blurred vision, irritability, convulsions, aphasia, limb sensory and motor disorders, and mental disorders.
3.Accelerated malignant hypertension: It is caused by various reasons of blood pressure continues to rise significantly (DBP often >130mmHg), the condition develops rapidly, and serious retinopathy (K-W fundus grade III or more) and renal dysfunction appear, if not timely and appropriate treatment, easily lead to uremia, acute left heart failure, and even death. The prognosis is poor. The fundus changes are retinal hemorrhage and exudation for acute hypertension, and malignant hypertension if optic papilloedema is present.
The disease is a specific type of hypertension with typical pathological changes of small arterial fibrous necrosis and/or proliferative sclerosis, with the most pronounced changes in the kidneys. All types of hypertension can develop into acute malignant hypertension, among which those caused by kidney disease are the most frequent.
Second, the principle of treatment
1.Rapidly lower blood pressure Select suitable and effective antihypertensive drugs, place an intravenous infusion tube, and administer the drugs by intravenous drip, while blood pressure should be constantly measured or non-invasive blood pressure monitoring. The advantage of intravenous drip drug delivery is that it is easy to adjust the dose of the drug. If the situation allows, early start oral antihypertensive drug treatment.
2.Controlled blood pressure lowering In hypertensive emergencies, a sharp drop in blood pressure within a short period of time may significantly reduce the blood perfusion of important organs, so a gradual controlled blood pressure lowering should be adopted, that is, the blood pressure should be lowered by 20%-25% within the first 24 hours, and the blood pressure should not be lower than 160/100mmHg within 48 hours. The blood pressure should be reduced even less if ischemia of vital organs is detected after the lowering. In the following 1-2 weeks, then gradually lower the blood pressure to normal levels.
3.Rational selection of antihypertensive drugs The selection of antihypertensive drugs for the treatment of hypertensive emergencies requires rapid onset of action, maximum effect within a short period of time; short duration of action; fast disappearance of action after stopping the drug; less adverse reactions. In addition, it is best not to significantly affect the heart rate, cardiac output and cerebral blood flow in the process of lowering blood pressure. Sodium nitroprusside, nitroglycerin, nicardipine and diltiazem injection are relatively ideal. In most cases, sodium nitroprusside is often the drug of choice.
4, drugs to avoid It should be noted that some antihypertensive drugs are not suitable for hypertensive emergencies, or even harmful. The antihypertensive effect of intramuscular injection of lispro is slow to start, and if repeatedly injected within a short period of time leads to unpredictable accumulation effects and severe hypotension; causes obvious drowsiness reaction. It may interfere with the judgment of mental status.
Therefore, the treatment of hypertensive emergencies with reserpine is not recommended. It is also not advisable to use powerful diuretic antihypertensive drugs at the beginning of treatment unless there is heart failure or obvious fluid volume overload, because in most hypertensive emergencies the sympathetic nervous system and RAAs are overactivated, peripheral vascular resistance is significantly increased, and the circulating blood volume in the patient’s body is reduced, and powerful diuresis is dangerous.
Three, antihypertensive drugs and applications
1, sodium nitroprusside: can simultaneously dilate the veins and arteries, reduce the anterior and posterior loads, start with 50mg/500ml concentration of 10-25ug per minute rate of sedation, immediately play a hypotensive effect, the use of sodium nitroprusside must be closely observed blood pressure, according to blood pressure level to adjust the drip rate, a slight change can cause large fluctuations in blood pressure. After stopping the drip, the effect is only maintained for 3-5 minutes. Sodium nitroprusside can be used in a variety of hypertensive emergencies, with mild adverse effects at usual doses, including nausea, vomiting, and muscle tremors.
Local tissue and skin reactions can be caused by extravasation of the drug at the drip site. Sodium nitroprusside is metabolized to cyanide in red blood cells in the body, and thiocyanate poisoning may occur with long-term or high doses, especially in those with renal impairment.
2, nitroglycerin: dilate veins and selectively dilate coronary arteries and aorta, start with 5-10ug per minute rate of sedation, then increase the drip rate to 20-50ug per minute per minute. Nitroglycerin is mainly used for hypertensive emergencies in acute left heart failure or acute coronary syndrome. Adverse reactions include tachycardia, facial flushing, headache, vomiting, etc.
3, Nicardipine: dihydropyridine calcium channel antagonist, rapid action, short duration, antihypertensive effect while improving cerebral blood flow. Start from 0.5ug/kg per minute intravenous drip, gradually increase the dose to 6ug/kg per minute, mainly used for hypertensive crisis or acute cerebrovascular disease, hypertensive emergencies, adverse effects include tachycardia, facial flushing, etc.
4, diltiazem: non-dihydropyridine calcium channel antagonist, antihypertensive at the same time with improved coronary blood flow and control of rapid supraventricular arrhythmias. Configured into 50mg/500ml concentration, at a rate of 5~15mg per hour, and adjust the rate according to the change of blood pressure. It is mainly used for hypertensive crisis or acute coronary syndrome. Adverse reactions include facial flushing, headache, etc.
5.Labridil: beta blocker with alpha-blocker, rapid onset of action (5-10 minutes), but longer duration (3-6 hours). Start with a slow sedative injection of 50mg, then can be repeated every 15 minutes, the total dose does not exceed 300mg, but also at a rate of 0.5mg to 2mg per minute intravenous drip. It is mainly used for hypertensive emergencies in pregnancy or renal failure. Adverse reactions include upright hypotension, heart block, dizziness, etc.
Fourth, several common hypertensive emergencies principles of management
1, hypertensive encephalopathy: make the blood pressure fall to the level of 140-160 mmHg systolic pressure within 2-3 hours, but do not reduce more than 25% of the mean arterial pressure, because sodium nitroprusside requires strict monitoring conditions and can make the intracranial pressure rise and affect cerebral perfusion, so the application of this drug is limited. Nicardipine can gradually lower blood pressure and maintain cerebral blood flow by injection or sedation.
2. Acute ischemic stroke: cerebral thrombosis and cerebral embolism are common. In the early stage, blood pressure may rise compensatingly to ensure the blood supply around the lesion, and later it may fall automatically due to the dysregulation of cerebral circulation. Therefore, caution is needed in lowering blood pressure in such patients. If the diastolic blood pressure is >130 mmHg, the blood pressure can be carefully lowered to 110 mmHg. A slightly higher blood pressure is beneficial to the perfusion of the ischemic area, and a low blood pressure should be avoided to reduce cerebral perfusion and increase the infarct area. If emergency thrombolytic therapy is considered, blood pressure should be lowered to 185/110 mmHg to prevent bleeding due to hypertension.
3, cerebral hemorrhage: blood pressure often increases significantly immediately after cerebral hemorrhage, which is due to the compensatory response to ensure blood supply to brain tissue when intracranial pressure is elevated. Therefore, the first step should be to lower the cranial pressure, including dehydration with mannitol, tachyphylaxis and other drugs, surgical elimination of hematoma and ventricular drainage. However, persistently high blood pressure can cause rebleeding or persistent bleeding, and it is currently believed that a systolic blood pressure >200 mmHg and diastolic blood pressure >130 mmHg can aggravate bleeding.
The lowering of blood pressure in cerebral hemorrhage should be carried out cautiously, and should be done gradually within 6-12h, with the magnitude of lowering not more than 25%. The application of sodium nitroprusside needs to pay attention to the increase of intracranial pressure and cerebral blood perfusion, and it is contraindicated if there is an increase of intracranial pressure.
4. Subarachnoid hemorrhage: It is often accompanied by cerebral vasospasm which aggravates the fluctuation of cerebral perfusion. An analysis of controlled trials of nimodipine versus placebo groups concluded that nimodipine reduced the risk of such patients by 42% compared to the placebo group. It is advocated to lower the blood pressure to normal levels in order not to affect the patient’s consciousness and cerebral perfusion.
5, aortic coarctation: the morbidity and mortality rate is very high, and it is necessary to rapidly lower the blood pressure, generally requiring a systolic blood pressure of 100-120 mmHg and a mean arterial pressure of <80 mmHg. lowering the blood pressure also reduces the decompression effect on the aortic wall. The classical drug treatment is sodium nitroprusside combined with β-blockers to lower blood pressure.
6, acute left heart failure: rapid reduction of blood pressure to normal can reduce the left ventricular preload and afterload. Sodium nitroprusside can reduce the pre and afterload of the heart and improve cardiac function. Angiotensin-converting enzyme inhibitor (ACEI) nitrate preparations can also be used effectively.
7, pheochromocytoma: can cause hypertensive crisis, preferred phentolamine or labetalol, or a combination of both can effectively block alpha receptors, peripheral vasodilation, blood pressure can be rapidly reduced.