What is considered hypotension that requires intravenous (IV) fluid administration?

From the Guidelines

Hypotension requiring vasopressor drip therapy typically occurs when systolic blood pressure falls below 90 mmHg or mean arterial pressure (MAP) drops below 65 mmHg, especially when accompanied by signs of inadequate tissue perfusion despite adequate fluid resuscitation.

Key Considerations

• The definition of hypotension can vary depending on the context and underlying condition of the patient, but a MAP below 65 mmHg is a commonly accepted threshold for considering vasopressor support 1.
• First-line vasopressors include norepinephrine, which is preferred for most types of shock due to its balanced alpha and beta effects 2.
• Before starting vasopressors, ensure adequate fluid resuscitation has been attempted, central venous access is established when possible, and continuous blood pressure monitoring is in place 3.
• The treatment of hypotension should be based on presumed underlying causes including vasodilation, hypovolaemia, bradycardia, and low cardiac output 4.

Management Approach

• Assess the patient's volume status and cardiac function to determine the underlying cause of hypotension.
• Use fluid resuscitation to correct hypovolemia, and consider vasopressors if hypotension persists despite adequate fluid administration.
• Choose the appropriate vasopressor based on the patient's condition, such as norepinephrine for most types of shock or phenylephrine for specific scenarios where tachycardia is concerning.
• Monitor the patient's response to treatment and adjust the vasopressor dose as needed to maintain adequate blood pressure and perfusion.

Recent Guidelines

• The most recent guidelines recommend a patient-centered approach to managing hypotension, taking into account the underlying cause and individual patient factors 4.
• The use of vasopressors should be guided by the patient's response to treatment, with ongoing monitoring of blood pressure, cardiac output, and other relevant parameters.

From the Research

Definition of Hypotension

Hypotension is generally defined as a systolic blood pressure (SBP) less than 90 mmHg or a mean arterial pressure (MAP) less than 65 mmHg 5, 6, 7. However, the definition of hypotension may vary depending on the context and population being studied.

Hypotension in Different Contexts

• In patients with septic shock, hypotension is defined as a SBP less than 90 mmHg or a MAP less than 65 mmHg after a crystalloid fluid challenge of 30 mL per kg body weight 5.
• In intraoperative settings, hypotension is defined as a SBP less than 90 mmHg or a MAP less than 65 mmHg for at least 10 minutes, or a need for noradrenaline infusion of at least 0.05 μg/kg/min for ≥10 minutes 6.
• In cardiac intensive care unit patients, hypotension is defined as a SBP less than 90 mmHg or a MAP less than 60 mmHg 7.
• In trauma patients, the definition of hypotension varies with age, with a SBP less than 100 mmHg for patients 20-49 years, less than 120 mmHg for patients 50-69 years, and less than 140 mmHg for patients 70 years and older 8.

Mean Arterial Pressure (MAP) as an Alternative Measurement

Some studies suggest that MAP may be a more appropriate measurement than SBP for detecting hypotension, as it is a better indicator of tissue perfusion 9. A MAP less than 70 mmHg has been proposed as a threshold for detecting hypotension during hemapheresis 9.

Key Points

• Hypotension is a critical condition that requires prompt attention and treatment.
• The definition of hypotension may vary depending on the context and population being studied.
• MAP may be a more appropriate measurement than SBP for detecting hypotension in certain situations.
• The treatment of hypotension typically involves fluid resuscitation and vasopressor support, as needed 5, 6, 7.