Are bradycardia (abnormally slow heart rate) and hypotension (low blood pressure) signs of volume depletion (hypovolemia)?

From the Guidelines

Bradycardia and hypotension are not typically signs of volume depletion, and instead suggest other conditions such as vasovagal syncope, certain medication effects, hypothyroidism, increased intracranial pressure, or cardiogenic shock. In fact, volume depletion (hypovolemia) usually causes tachycardia (increased heart rate) as the body attempts to maintain cardiac output despite reduced blood volume, as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. The typical presentation of volume depletion includes tachycardia, hypotension, decreased skin turgor, dry mucous membranes, reduced urine output, and orthostatic hypotension (blood pressure drop when standing).

Some key points to consider in the evaluation of bradycardia and hypotension include:

• The body's normal compensatory response to reduced blood volume is to increase heart rate to maintain adequate tissue perfusion
• Bradycardia with hypotension may indicate a more complex underlying condition, such as cardiogenic shock or increased intracranial pressure
• Certain medications, such as beta-blockers and calcium channel blockers, can cause bradycardia and hypotension
• Hypothyroidism can also cause bradycardia and hypotension, as noted in various studies, including those on post-resuscitation care 1

When evaluating a patient with bradycardia and hypotension, it is essential to consider these alternative diagnoses and to assess the patient's clinical status and identify potentially reversible causes, as recommended in the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. The treatment approach for bradycardia and hypotension will depend on the underlying cause, and may involve expert consultation, transvenous pacing, or other interventions.

From the FDA Drug Label

Blood volume depletion should always be corrected as fully as possible before any vasopressor is administered. LEVOPHED should not be given to patients who are hypotensive from blood volume deficits except as an emergency measure to maintain coronary and cerebral artery perfusion until blood volume replacement therapy can be completed

Bradycardia and hypotension can be signs of volume depletion. According to the drug label, blood volume depletion should be corrected before administering a vasopressor, and norepinephrine should not be given to patients who are hypotensive from blood volume deficits, except in emergency situations 2, 2.

• Key points:
  • Blood volume depletion should be corrected before vasopressor administration
  • Hypotension from blood volume deficits is a contraindication for norepinephrine, except in emergencies
  • Bradycardia and hypotension may indicate volume depletion, which should be addressed before or concurrently with vasopressor therapy.

From the Research

Bradycardia and Hypotension

• Bradycardia is a heart rate lower than 60 beats/min, and it can be due to various causes, including sinus, atrial, or junctional bradycardia or problems with the conduction system 3
• Hypotension can be a sign of significant underlying pathology, and if not rapidly identified and addressed, it can contribute to organ injury 4
• The combination of bradycardia and hypotension can be a true medical emergency, especially in patients with chronic hypertension, and often requires hospitalization for detailed interrogation of the underlying causes 5

Volume Depletion

• Volume depletion can lead to hypotension, and the choice of fluid for resuscitation remains controversial, with both colloid and crystalloid solutions having their advantages and disadvantages 6, 7
• Crystalloid fluid repletion may require larger volumes than colloidal fluid and can increase the risk of pulmonary edema, especially in older patients 7
• The treatment of hypotension is best targeted at the underlying etiology, and expedited bedside evaluation with rapid initiation of treatment based on the most likely underlying etiology is paramount 4

Relationship between Bradycardia, Hypotension, and Volume Depletion

• While there is no direct evidence that bradycardia and hypotension are exclusive signs of volume depletion, hypotension can be a sign of significant underlying pathology, including volume depletion 4
• The presence of bradycardia and hypotension together can indicate a more severe underlying condition, and treatment should be targeted at the underlying cause, which may include volume depletion 5, 4