Tachycardia and Hypotension in Asthma

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I am currently in my first semester of nursing school and doing a case study about asthma. In the scenario, the patient has tachycardia and hypotension. These symptoms are always mentioned as being symptoms of a severe asthma exacerbation, however, I don't understand the mechanism by which they occur. i.e. why do they happen in severe asthma. I was wondering if anybody could help me with this please?

Thank you!

Specializes in PICU, Sedation/Radiology, PACU.

The heart is responsible for pumping blood through the body. One of the essential elements in that blood is oxygen. During an asthma attack, there are inadequate levels of oxygen in the blood. The heart tries to compensate for low oxygen levels by pumping faster- trying to deliver more blood/oxygen to the tissues.

Hypotension is more multifactorial. Remember that a major component of blood pressure is cardiac output (influenced by heart rate, force of the heart beat, and amount of blood in the heart). A process that contributes to hypotension in severe asthma is called dynamic hyperinflation. In simple terms, one breath isn't finished exhaling before another is inhaled. This leads to air trapping, increased pressure and over inflation of the lungs. In turn, resistance in the inferior vena cava is increased. This makes it harder for blood to get back to the heart, so cardiac output is decreased, thus decreasing blood pressure.

In an severe untreated asthma, hypotension may also be secondary to severe hypoxia. Muscles (like the heart) need oxygen in order to function. When there is a lack of oxygen, the heart begins to fail, contractions/heart beats become weak and blood is not pumped effectively.

Hope this helps!

Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

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Double helix was very kind to be so helpful...we ask that nursing students tell us what they think first so we can help you fully understand to find the solution yourself.

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