Pulse Ox And Stroke: What's The Connection?

A stroke occurs when the brain is deprived of oxygen, which can happen when the blood flow to the brain is blocked or when a blood vessel in or around the brain leaks or bursts. A lower-than-normal concentration of oxygen in the blood, known as mild hypoxia, is common in stroke patients and can lead to further damage to the brain. Oxygen treatment is widely used after a stroke, but it can have adverse effects, and there is limited evidence for its effectiveness. While oxygen is vital for the brain, low blood oxygen levels can occur for a variety of reasons and do not necessarily indicate that a stroke is imminent.

What is a stroke?

A stroke is a life-threatening medical emergency that occurs when there is an issue with blood flow to the brain. It is often referred to as a "brain attack" or the brain's equivalent of a heart attack. A stroke can happen when blood vessels are blocked, or because of bleeding in the brain. When blood flow to the brain is blocked, it is called an ischemic stroke, and when there is sudden bleeding in the brain, it is called a hemorrhagic stroke.

During a stroke, the brain does not receive enough oxygen, which is essential for brain cells to function and survive. Brain cells begin to die within minutes of oxygen deprivation, and the longer the brain goes without oxygen, the more severe the damage can be. With each minute that passes, about 2 million brain cells are lost. After around 10 minutes, the damage can be severe and permanent.

The two main types of strokes, ischemic and hemorrhagic, affect blood flow to the brain in different ways. Ischemic strokes occur when an artery that brings blood to the brain gets clogged, usually by a blood clot, and blood cannot flow through it. This is the most common type of stroke, accounting for about 80% of all strokes. Hemorrhagic strokes, on the other hand, happen when a blood vessel in or around the brain leaks or bursts, leading to bleeding in or around the brain. This type of stroke is less common.

Strokes are a leading cause of disability and death worldwide. They can cause lasting brain damage, long-term disability, or even death. The signs and symptoms of a stroke can vary but often include weakness or paralysis on one side of the face or body, loss of balance, sudden loss of vision, difficulty speaking or understanding speech, severe headache, and confusion.

If you or someone else is exhibiting signs of a stroke, it is crucial to call emergency services immediately. Time is of the essence when it comes to treating strokes, and every minute counts in preventing permanent brain damage or death. At the hospital, a stroke team will assess and treat the stroke using various methods, including medication, surgery, or other procedures. The recovery from a stroke depends on the severity of the stroke and the speed of treatment.

What is the link between low pulse ox and a stroke?

A stroke is a "brain attack" where the brain doesn't get enough blood, which means it isn't getting enough oxygen. Brain cells need a steady flow of blood to work well as they have no oxygen or glucose stores of their own. Brain cells start to die if they go without oxygen for just 3-4 minutes.

Hypoxia is a common occurrence following a stroke and is associated with poor clinical and functional outcomes. It is caused by a disruption of oxygen delivery to the brain, which can be due to pneumonia, aspiration, respiratory muscle dysfunction, sleep apnoea syndromes, pulmonary embolism, and cardiac failure.

Oxygen therapy is a vital element in correcting hypoxia, but excessive use can cause molecular and clinical harm. Randomised clinical trials have not shown benefit in the use of supplemental oxygen therapy. However, it is vital to rapidly identify and treat all causes of hypoxia in acute stroke patients as a failure to do so will lead to poorer clinical outcomes.

Low blood oxygen levels (hypoxemia) can lead to serious complications and damage to individual organ systems, especially the brain and heart. A lower-than-normal blood oxygen level is called hypoxemia. Since oxygen is essential to all of the body's functions, hypoxemia is often concerning.

The lower the oxygen level, the greater the likelihood of complications in body tissue and organs. A blood oxygen level test can be performed through a blood draw test or pulse oximetry (using an oximeter).

What are the causes of a stroke?

A stroke is a "brain attack" where the brain is starved of oxygen due to a lack of blood flow. This can happen in two ways:

• Ischemic stroke: An artery that brings blood to the brain gets clogged up, causing a blockage in blood flow. This is the most common type of stroke and accounts for about 87% of strokes. The blockage in the brain is usually caused by a piece of plaque or a blood clot. If the blockage occurs locally in the brain, the condition is called thrombosis. If the blood clot travels from somewhere else in the body, it is called an embolism.
• Hemorrhagic stroke: A blood vessel in or around the brain leaks or bursts, causing bleeding in the brain. This is less common and includes intracerebral hemorrhage and subarachnoid hemorrhage. Intracerebral hemorrhage occurs when a blood vessel inside the brain bursts or leaks, while subarachnoid hemorrhage occurs when a blood vessel around the brain bursts or leaks, bleeding into the area between the brain and the tissue around it.

Certain conditions increase the risk of stroke, including:

• High blood pressure (hypertension)
• Irregular and fast heartbeats (atrial fibrillation)
• Transient ischemic attack (TIA or mini-stroke)
• Sickle cell disease (SCD)
• Pregnancy and pre-eclampsia
• Unhealthy lifestyle
• Taking the combined contraceptive pill
• Age: The risk increases if you are over 50 or a baby under the age of 1
• Race and ethnicity: In the United States, stroke occurs more often in Black, Alaska Native, American Indian, and Hispanic adults than in white adults.
• Genetic factors: History of stroke in the family, particularly at a younger age, increases risk. People with blood type AB also have a higher risk.
• Lifestyle factors: High stress levels, working long hours, lack of social contact, unhealthy lifestyle habits such as excessive alcohol consumption, oversleeping (more than 9 hours), and use of illegal drugs such as cocaine may increase risk.
• Other medical conditions: Conditions such as sleep apnea, kidney disease, migraine headaches, diabetes, high blood cholesterol, coronary heart disease, heart valve disease, carotid artery disease, and viral infections or autoimmune conditions like lupus or rheumatoid arthritis can increase the risk of stroke.

It is important to note that having a stroke increases the risk of having another one, so taking preventive measures and managing underlying conditions is crucial.

How to identify a stroke?

A stroke is a serious medical condition that requires immediate attention. It occurs when the brain is deprived of oxygen due to disrupted blood flow, which can be caused by a blocked or burst blood vessel. The effects of a stroke depend on the area of the brain that is affected and the duration of oxygen deprivation. Brain cells can start to die within 3-4 minutes of oxygen deprivation, and the risk of severe brain damage increases with time. Therefore, it is crucial to recognise the signs of a stroke and act quickly.

• Face Drooping: Ask the person to smile and observe if one side of their face droops or feels numb.
• Arm Weakness: Instruct the person to raise both arms and check if one arm drifts downward due to weakness.
• Speech Difficulty: Request the person to repeat a simple phrase and listen for slurred or strange speech.
• Time Sensitivity: If you observe any of the above signs, call emergency services immediately. Note the time when the symptoms first appeared, as every minute counts in stroke treatment.

Additionally, other warning signs and symptoms of a stroke may include:

• Sudden confusion, difficulty speaking or understanding speech.
• Sudden numbness or weakness, especially on one side of the body.
• Sudden severe headache with no apparent cause.
• Sudden trouble seeing from one or both eyes.
• Sudden difficulty walking, dizziness, or loss of balance or coordination.
• Clumsiness or poor coordination.
• Loss or dimming of senses, including smell and taste.

Remember, the FAST test (Face, Arms, Speech, Time) is a quick and easy way to identify the most common signs of a stroke. However, strokes can present with various symptoms depending on the area of the brain affected, so it is essential to seek immediate medical attention if you suspect a stroke, even if the symptoms are mild or temporary.

How to treat a stroke?

A stroke is a life-threatening condition that requires emergency medical care. Treatment depends on the type of stroke, how much time has passed since the first symptoms, and the patient's medical history. Here are some ways to treat a stroke:

Treating an Ischemic Stroke

Ischemic strokes are the most common type, caused by a blocked artery that interrupts blood flow to the brain. Treatment options include:

• Thrombolytic drugs, such as tissue plasminogen activator (tPA), which break up blood clots. tPA must be administered within 3 hours of the first stroke symptoms, and sometimes up to 4.5 hours.
• Anticoagulants or blood-thinning medications like aspirin or clopidogrel to prevent new clots from forming or growing.
• Thrombectomy, a procedure where a surgeon uses a catheter to remove the clot from the blocked blood vessel.
• Angioplasty and stenting, a procedure that uses a balloon or mesh tube to clear space in the blocked artery and allow blood flow to the brain.
• Stent retriever, a device that traps the clot so it can be removed through the catheter.

Treating a Hemorrhagic Stroke

Hemorrhagic strokes are caused by a leaking or burst blood vessel in the brain and require urgent treatment. Treatment options include:

• Blood pressure medication to lower pressure on blood vessels in the brain.
• Vitamin K to stop bleeding if the patient was taking anticoagulants.
• Aneurysm clipping, a surgery to block off the aneurysm and prevent further bleeding.
• Coil embolization, a procedure that uses a coil to block blood flow to the aneurysm and prevent it from bursting.
• Surgery to drain excess fluid that is putting pressure on the brain.
• Carotid endarterectomy, a surgery to remove plaque buildup from the carotid artery in the neck.

Other Treatments and Supportive Care

In addition to the treatments above, patients may require:

• Breathing support, such as ventilator assistance, if the stroke affects their ability to breathe.
• Compression therapy to lower the risk of venous thromboembolism.
• A feeding tube if the patient has difficulty swallowing.
• Intravenous fluids to restore proper blood pressure and volume.
• Fever-reducing medications to prevent additional brain damage.
• Rehabilitation plans, including speech, physical, and occupational therapy, to aid in recovery and prevent another stroke.
• Palliative or hospice care to improve quality of life and manage symptoms.

Frequently asked questions