Checking blood pressure is an important part of evaluating your patient. Unfortunately, a problem doesn’t always announce itself with a fanfare of trumpets. Even the highest blood pressure can be entirely asymptomatic. Similarly, low blood pressure also known as hypotension can occur in your patient despite no symptoms seemingly being present. This is particularly true if the patient is lying still in an unmonitored bed.
What is Hypotension?
Of course, the easiest way to know your patient has a blood pressure problem is by simply taking their pressure, but in some cases you may notice other symptoms that prompt you to check a pressure and find that it is low. Low blood pressure means poor perfusion, and it can be just as problematic as higher pressures.
The best objective symptom of a low blood pressure is taking an actual pressure and getting low numbers. It sounds obvious, but it may not occur to you to take a pressure when a patient complains of certain symptoms. When a patient does complain, however, it is usually recommended that you get a complete set of vitals, and this will point to a problem with low blood pressure. How low is too low? What does low actually mean? It can mean different things for different patients.
The usual metric for measuring low blood pressure is that anything below 90/50 mm Hg (millimetres of mercury) is considered low enough to treat. However, you can have a symptomatic patient at 100/60 mm Hg. This is still a low blood pressure problem, and it needs to be treated. You can also have symptoms of low blood pressure when someone with hypertension comes down from very high pressures. For instance, 120/80 mm Hg may be normal for everyone else, but if your patient lives at 190/100 mm Hg, they are going to feel the difference. For this reason, the objective sign of a pressure must be combined with the subjective symptoms the patient reports.
Subjective symptoms are those that the patient may report, though you may be able to see objective signs of these as well. With low blood pressure, the patient may feel faint or lose consciousness. This is due to lack of blood flow to the brain, and usually laying the patient supine will help them come round. This is also known as a blackout, and it could be accompanied by a dizzy feeling and light-headedness. Generally, your patient will report trouble focusing, difficulty keeping upright and lack of coordination.
Your patient may also report nausea and could possibly vomit from the low blood pressure. In addition, heart palpitations are sometimes felt, and these can be easily seen with the use of telemetry or other monitoring. EKGs/ECGs may or may not show them, depending on the frequency and timing of the palpitations. Some patients may also exhibit confusion, and this can make them seem like they are suffering from intoxication or some other neurological problem. Blurred vision is usually reported with extreme cases of low blood pressure. There are many other symptoms of low blood pressure to look out for.
Orthostasis literally means standing upright. Orthostatic hypotension, or postural hypotension, is defined as a decrease in systolic blood pressure of at least 20 mm Hg or at least 10mm Hg within 3 minutes of the patient standing. If orthostatic hypotension is present, the client may be at risk of falls. The accuracy of orthostatic hypotension has been questioned in recent years.
One quick way to treat symptomatic low blood pressure is to lay the head of the bed down and put up the patient’s feet. This will encourage blood flow to the brain and aid perfusion. You will also need to get a doctor’s order for fluids or electrolytes to help bring the blood pressure up to normal. Usually, 500 ml/cc of normal saline will be enough to raise the pressure above critical. Blood work should also be conducted to find out if there is an electrolyte imbalance that is leading to the loss of water.
Treatment generally focuses on why the patient’s pressure dropped. If they’ve lost a great deal of blood, getting the bleeding under control and giving blood products may be the necessary course. If the patient is on a cocktail of blood pressure-lowering medications, these will need to be adjusted to prevent the low event from happening again. As a nurse, you need to work with the doctor to find out the underlying cause of the low blood pressure to treat it beyond the normal emergency procedures of saline infusions and postural interventions.
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