What Causes Low Blood Pressure After Surgery

What causes low blood pressure after surgery?

The main cause of low blood pressure is a lack of oxygen to your body. You may have heard that there are different types of low blood pressure:

Acute (short term) – usually caused by trauma or illness. Usually the patient recovers within a few days. There is no need to worry about it!

Chronic (long term) – usually caused by chronic diseases such as diabetes, high cholesterol, smoking and other medical conditions. These patients may not recover at all. They require intensive care. If they die from their condition, then it is considered a tragedy.

Preventable – most cases of acute low blood pressure are preventable if you take proper precautions before having surgery and during the operation itself.

When is low blood pressure an emergency?

Low blood pressure is a very common problem that requires immediate attention. When the level of blood sugar drops too low, it may lead to coma and death. This happens because the brain does not receive enough oxygenated blood flow. The lower the concentration of glucose in your bloodstream, the less oxygen your brain receives. Your heart rate slows down and you become unconscious due to lack of oxygenation. The fatality rate is high.

Serious complications arise when the brain does not receive oxygen because it can no longer function properly. This could cause a stroke and permanent damage to the area of the brain. Slowing down the heart rate with drugs can also lead to heart attacks. Losing consciousness for any reason whatsoever also means that you are at risk of choking on your own vomit, which can be fatal in some cases.

How to tell if a person has low blood pressure?

The most common and dangerous condition that affects people with low blood pressure is fainting (syncope). It is caused by a sudden drop in blood flow to the brain. Most patients with hypotension suffer from this condition. The symptoms of syncope include the following:

Vision loss


Feeling of weakness or fatigue


How is low blood pressure diagnosed?

Your doctor will perform a physical examination to check the blood pressure in your arms and legs. If it is very low, then you will be diagnosed with hypotension. Your heart rate and the strength of your pulse will also be measured. Other measurements may include your respiratory rate and temperature. You may also need several blood tests to determine whether there is a serious underlying medical condition causing the hypotension.

What are the different types of low blood pressure?

There are four types of hypotension. The first one is called postural hypotension. This is the most common type and usually occurs when you change your body position, such as standing up too quickly. The blood pools in your legs and it takes a few minutes for your body to adjust. This explains why you may experience low blood pressure symptoms when you wake up.

The second type is cardio-vascular hypotension. This type is usually caused by blood thinners, and the most common cause is atrial fibrillation. Low blood pressure stemming from this condition can lead to serious complications such as blood clots, heart attacks and strokes.

Neurogenic hypotension is a result of damage to the autonomic nervous system (the nerves that control your heart rate and blood pressure). Causes of this type include Parkinson’s disease and diabetes.

The last type is called renal failure hypotension. It occurs when your kidneys lose their ability to regulate the amount of fluid and electrolytes in your blood, leading to low blood pressure.

What are the possible complications of low blood pressure?

When blood pressure drops too low, it can have a serious impact on the brain. A condition called hypoxia can lead to several complications:



Loss of vision

Difficulty breathing.

How is low blood pressure treated?

The management of low blood pressure depends upon the cause. In most cases, it may be managed with medication. The drugs that are used to increase the blood pressure in hypotensive patients can cause dizziness and fainting. If you have recently been diagnosed with hypotension, it is vital to avoid driving or operating heavy machinery. You may also need to check your blood pressure more frequently.

Sources & references used in this article:

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Adherence to the enhanced recovery after surgery protocol and outcomes after colorectal cancer surgery by UO Gustafsson, J Hausel, A Thorell… – … of surgery, 2011 – jamanetwork.com

Postoperative symptoms and failure after antireflux surgery by YS Khajanchee, RW O’Rourke, B Lockhart… – … of Surgery, 2002 – jamanetwork.com

Thoracic outlet syndrome: do we have clinical tests as predictors for the outcome after surgery? by M Sadeghi-Azandaryani, D Bürklein, A Ozimek… – European journal of …, 2009 – Springer

Outcome after surgery for primary hyperparathyroidism: ten-year prospective follow-up study by S Walgenbach, G Hommel, T Junginger – World journal of surgery, 2000 – Springer

Hyponatraemia after orthopaedic surgery: Ignorance of the effects of hyponatraemia after surgery is widespreadand damaging by N Lane, K Allen – 1999 – bmj.com