15 Underlying Causes of Tachycardia

It’s Valentine’s day, and cupid’s arrow has likely found its way to many a young heart, causing it to race with love.  Here’s a quick Valentine’s day review of the other causes of tachycardia.

First things first, if you have a patient who actually has an arrow lodged in his chest, I would advise treating this patient as a trauma, no matter how innocent the kid that shot him looks.

With that out of the way, lets take a quick look at the causes of tachycardia.  Sometimes the underlying cause of a patient’s tachycardia can be corrected in the field, while others may not.

Underlying Causes of Tachycardia

  • Anxiety

It is certainly not uncommon for a patient to work themselves up with anxiety.  Try to calm the patient yourself, or enlist the help of a loved one.  Ensure you explain what you are doing, and what the patient can expect next to help quell unneeded worry.

  • Fever

While obtaining a temperature on a patient is often one of the last things many providers do, it is still a very important vital sign.  It might just be the cause of your patient’s tachycardia as well.

  • Hypoglycemia

It’s probably safe to say that the majority of us are familiar with the fast and thready pulse of a bottomed-out diabetic patient.  Don’t forget that just because a patient does not have a history of diabetes, doesn’t mean that they aren’t hypoglycemic.

  • Respiratory Problems

Patients with respiratory distress are likely to have several factors behind their tachycardia.  The feeling of not being able to breathe combined with reduced alveolar oxygen supply can easily spike their pulse by way of sympathetic response.

  • Shock

In a patient with tachycardia, shock should always be high on your differential list.  Be sure to examine the possibility of each type of shock during your assessment.  Failing to identify shock early can lead to disastrous outcomes.

  • Trauma

It seems like trauma would be fairly obvious to most providers, but not always.  Take particular care in examining pediatric patients for trauma, due to their magician-like ability to conceal internal injuries.

Keep in mind that all of the above causes of tachycardia can usually be identified by the time you have obtained your first set of vital signs.  This reinforces the need to obtain a complete set of vital signs on every patient, if possible.

Slightly More Obscure Causes

The next few causes may require a little bit more detective work to determine.  A good SAMPLE history is the best place to start, questioning deeper when required.

  • Dehydration

Dehydration can happen at any time of year to anyone.  Keep this differential high on your list for all patients, particularly those who are elderly or report poor fluid intake or excessive fluid loss.

  • Electrolyte Disturbances

While electrolyte abnormalities can be difficult to pinpoint without laboratory studies, keep this in mind while obtaining your patient’s history.

  • Pain

All patients handle pain differently, and while it may be obvious in some, others may not bring it up unless specifically asked.

  • Toxic Ingestion/Poisoning

Toxins may be very obvious, or very difficult to uncover.  The patient may not even know that they have been exposed to a toxin or poison.  Keep your eyes open on scene for any indicators in addition to your history gathering.

  • Drug/Alcohol Withdrawal

Not entirely uncommon, but will likely only be identified through the patient’s history.

  • Pulmonary Embolism

Making a field diagnosis of PE is just not possible.  However, a suggestive history and physical exam, combined with EKG findings should raise your index of suspicion.

Very Obscure Causes

The last three causes of tachycardia are likely to not be uncovered in the field unless the patient has already been diagnosed.  Yes, there are some characteristic signs and symptoms of each of these conditions (or groups of conditions), but discussing them would be beyond the scope of this posting.  Additionally, using only signs and symptoms, it would be very difficult to make a field diagnosis with any degree of accuracy.  So here they are:

  • Anemia
  • Hyperthyroidism
  • Metabolic Disorders

But wait, what about dysrhythmias?

Last, but not least, I will mention cardiac dysrhythmias.  However, I am not going to discuss them in detail, as I feel it is necessary to devote an entire post at minimum to each type.  So keep an eye out for this in the future.

Well that’s all for today.  As simple as some of these causes may be, I encourage everyone to review the pathophysiology of each cause.  The better you understand a condition, the better you will be at identifying and managing it when you see it in the field.  Thanks for reading!  If you haven’t done so already, take a moment to follow my blog via e-mail so that you never miss a post.  You can also follow me on Facebook & Twitter.  Also, if you didn’t hear, I have published my personal field reference as an eBook available on Amazon here- Pocket Paramedicine.  Every sale helps support the site, and gives YOU some handy information at your fingertips.  Until next time, treat aggressively and avoid all of those stray arrows!


Nickson C. Tachycardia. LITFL: Life in the Fast Lane Medical Blog. [accessed 2017 Feb 13]. http://lifeinthefastlane.com/resources/tachycardia-ddx/

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