What is Hypertensive Emergency?
Hypertensive emergency is a condition of extremely high blood pressure, which has potentially fatal signs and symptoms signaling acute impairment of one or more than one organ systems.
Hypertensive urgency is a condition where a person has systolic blood pressure over 180 mmHg or a diastolic blood pressure above 110 mmHg. A condition where there is elevated blood pressure along with hypertensive urgency, but with additional signs of irreversible damage to the organs is termed as Hypertensive Emergency.
Pathophysiology of Hypertensive Emergency
The pathophysiology of hypertensive emergency is not clearly understood. There is a sudden increase in the systemic vascular resistance along with the following. endothelial dysfunction and injury; deposition of fibrin and platelets; fibrinoid necrosis of the arterioles and breakdown of normal autoregulatory function. This leads to ischemia, which triggers increased release of vasoactive substances, such as free radicals, prostaglandins; and mitotic/thrombotic growth factors. If this vicious cycle is not stopped, then there is homeostatic failure resulting in loss of local and cerebral auto-regulation along with organ system dysfunction and ischemia; and myocardial infarction.
Pathological changes in brain due to hypertensive emergency includes: swelling of the optic disc, hypertensive encephalopathy; all of which is a result of dysfunction of cerebral auto-regulation.
Pathological changes in heart due to hypertensive emergency includes: increased systolic blood pressure, increased arterial stiffness and widened pulse pressures all caused by chronic hypertension resulting in significant damage. There is decrease in coronary perfusion pressures due to this, and also increase in myocardial oxygen consumption, which may cause left ventricular hypertrophy. Patient may also have pulmonary edema, left ventricular failure and myocardial ischemia.
Pathological changes in kidneys due to hypertensive emergency includes: pathologic changes in the small arteries of the kidney. There is impairment of normal vasodilation and endothelial dysfunction in the kidneys, which change the renal auto-regulation. With the disruption of the renal autoregulatory system, there is direct variation in the intra-glomerular pressure with the systemic arterial pressure, which provides no kidney protection from the fluctuations in the blood pressure.
There may also be activation of the renin-aldosterone-angiotensin system resulting in increased vasoconstriction and damage. In hypertensive emergency, this can result in acute renal ischemia, with hypoperfusion and also involves other organs and their subsequent impairment.
What are the Causes of Hypertensive Emergency?
The most common cause of Hypertensive Emergency is discontinuation of anti-hypertensive medications by patients suffering from chronic hypertension.
Other causes of Hypertensive Emergency include:
- Collagen-vascular diseases.
- Use of certain drugs; especially stimulants.
- Use and abuse of amphetamines and cocaine.
- Disorders of the spinal cord.
- Renovascular hypertension.
- Trauma to the head.
- Preeclampsia and eclampsia.
Withdrawing from medications, such as beta-blockers or clonidine also leads to hypertensive emergency.
What are the Signs & Symptoms of Hypertensive Emergency?
Common signs & symptoms of hypertensive emergency are:
- Brain Symptoms of Hypertensive Emergency. Increased pressure within the cranium causes symptoms, such as nausea, headache, vomiting. There is also cerebral infarction, hypertensive encephalopathy, cerebral or subarachnoid hemorrhage.
- Eye Symptoms of Hypertensive Emergency. Retinal bleeding; papilledema and scattered splinter hemorrhages in the eye.
- Cardiac Symptoms of Hypertensive Emergency. Patient also can suffer from pain in the chest pain as a result of increased workload on the heart due to hypertensive emergency. Congestive heart failure can also result from hypertensive emergency. Patient may have also left ventricular dysfunction due to this.
- Renal Symptoms of Hypertensive Emergency. Hypertensive emergency affects the kidneys also, which causes blood and/or protein in the urine, along with acute kidney failure. Patients suffering from hypertensive emergency also experience edema, oliguria and confusion.
- Other signs and symptoms of hypertensive emergency are abnormal heart rhythms, persistent nosebleeds, dyspnea, fainting, agitation, acute anxiety, abnormal sensations and change in mental state.
- Less common signs and symptoms of hypertensive emergency are aortic dissection, intracranial bleeding and pre-eclampsia or eclampsia.
Diagnosis of Hypertensive Emergency
For diagnosing hypertensive emergency and its cause, patient’s blood pressure is taken on both the arms. Tests that need to be done to diagnose hypertensive emergency include blood glucose, urine toxicology, complete metabolic panel to assess liver function, a basic metabolic panel to assess kidney function, chest x-rays, EKG and pregnancy screening.
What is the Treatment for Hypertensive Emergency?
The initial line of treatment in hypertensive emergency is stabilizing the patient’s breathing, airway and circulation. Treatment for hypertensive emergency consists of gradually bringing down the patient’s blood pressure over a period of minutes to hours with the use of an antihypertensive drug. In hypertensive emergency, if the blood pressure is lowered rapidly, then it puts the patient at high risk of complications, such as blindness, stroke or kidney failure.
- The aim of reduction of blood pressure in hypertensive emergency is less than or equal to 25% within the first 8 hours of emergency in the mean arterial pressure.
- There are various classes of antihypertensive agents used for treating hypertensive emergency, depending on the cause, the degree of increase in blood pressure, baseline blood pressure of the patient before suffering from hypertensive emergency.
- Tests done to diagnose the cause of hypertensive emergency include. chest x-ray, urinalysis, serum laboratory studies to assess kidney function. Depending on the test results, the treatment is decided for hypertensive emergency.
- In Hypertensive Emergency, treatment consists of intravenous use of anti-hypertensive agents and they are given by injections intramuscularly. Anti-hypertensive agents used for treating Hypertensive Emergency include. beta-blockers, systemic vasodilators and calcium channel blockers.
- The basis of hypertensive emergency is not only the actual increased level of blood pressure, but also depends on the patient’s baseline blood pressure before hypertensive emergency.
- Patient having a history of chronic hypertension cannot withstand a “normal” blood pressure and can experience symptoms of hypotension, such as lightheadedness, fatigue, vomiting, nausea or syncope.
What is the Prognosis & Life Expectancy of Hypertensive Emergency?
The prognosis of hypertensive emergency without immediate treatment is poor. Hypertensive emergency is a serious and potentially fatal condition. Patients suffering from hypertensive emergency and who have not received the right treatment have an average life span of around 3 years after the incident.
The prognosis, which includes the morbidity and mortality of hypertensive emergency, depends on the severity of the end-organ impairment at the time of hypertensive emergency and the degree to which the blood pressure is managed and brought down later. If the patient suffering from hypertensive emergency is able to achieve good blood pressure control and follows medication, then there are about 70% chances of the 10-year survival rate for the patient.