What is the management for hypotension?

Management of Hypotension

The most critical first step in managing hypotension is identifying the underlying physiological cause—vasodilation, hypovolaemia, bradycardia, or low cardiac output—because treatment differs fundamentally based on etiology, and only approximately 50% of hypotensive patients are actually fluid-responsive. 1, 2

Initial Diagnostic Assessment

Before initiating treatment, perform a passive leg raise (PLR) test to determine fluid responsiveness 3, 1, 2:

• An increase in cardiac output after PLR strongly predicts fluid responsiveness (positive likelihood ratio = 11; 95% CI, 7.6-17; pooled specificity 92%) 3, 1
• No increase in cardiac output after PLR indicates the patient will likely not respond to fluid (negative likelihood ratio = 0.13; 95% CI, 0.07-0.22; pooled sensitivity 88%) 3, 1
• This test is critical because in postoperative patients with suspected hypovolaemia, only 54% actually respond to fluid boluses, meaning approximately 50% require correction of vascular tone or inotropy instead 3, 1, 2

Cause-Directed Treatment Algorithm

For Hypovolaemia (Positive PLR Test)

• Administer crystalloid fluid bolus: 250-500 mL in adults 1, 2 or 10-20 mL/kg (maximum 1,000 mL) in children 3, 1
• Use 0.9% sodium chloride or balanced crystalloid solution as the initial fluid of choice 3
• Avoid hypotonic solutions such as Ringer's lactate in patients with severe head trauma 3
• Restrict colloid use due to adverse effects on haemostasis 3

For Vasodilation (Negative PLR Test with Low Vascular Tone)

• Norepinephrine is the first-line vasopressor for hypotension due to vasodilation 1, 2, 4
• Phenylephrine is best for hypotension with tachycardia, as it causes reflex bradycardia 1, 2
• Vasopressin can be added when hypotension persists despite norepinephrine (bolus of 4 IU followed by 0.04 IU/min decreases blood product requirements in hemorrhagic shock) 3

For Bradycardia

• Atropine or glycopyrronium is first-line treatment for bradycardia-induced hypotension 1, 2
• Use epinephrine or isoprenaline if refractory 1
• Consider pacing for profound bradycardia 1

For Low Cardiac Output/Myocardial Dysfunction

• Dobutamine is recommended for low cardiac output from myocardial dysfunction 3, 1, 2
• Epinephrine is an alternative positive inotrope 1, 2

Context-Specific Blood Pressure Targets

Trauma Without Brain Injury

• Use restricted volume replacement with target systolic blood pressure of 80-90 mmHg (mean arterial pressure 50-60 mmHg) until major bleeding is controlled 3, 1, 2
• This permissive hypotension strategy reduces mortality compared to aggressive fluid resuscitation 1, 2
• If systolic blood pressure falls below 80 mmHg despite restricted fluids, add transient norepinephrine to maintain life and tissue perfusion 3

Severe Traumatic Brain Injury

• Maintain mean arterial pressure ≥80 mmHg to ensure adequate cerebral perfusion 1, 2
• Do NOT use permissive hypotension in this population 1, 2

Postoperative Patients

• Target systolic blood pressure >90 mmHg or mean arterial pressure >70 mmHg 3
• Perform structured bedside assessment to determine if patient is stable or unstable 3
• Unstable patients with end-organ dysfunction require high acuity care setting 3

Patients with Elevated Compartment Pressures

• Increase mean arterial pressure target by roughly the compartment pressure to account for increased venous outflow pressure 1, 2

Critical Pitfalls to Avoid

• Do NOT reflexively administer fluids without assessing fluid responsiveness—approximately 50% of hypotensive patients are not hypovolemic and require vasopressors or inotropes instead 3, 1, 2
• Avoid aggressive fluid resuscitation in trauma without brain injury—it increases mortality 1, 2
• Never use permissive hypotension in traumatic brain injury—maintain MAP ≥80 mmHg 1, 2
• Avoid additional fluid boluses in patients with cardiac dysfunction or volume overload signs (pulmonary edema) 3
• Do not use dopamine as first-line; if hypotension persists at lower infusion rates, switch to norepinephrine as a more potent vasoconstrictor 5

Monitoring Recommendations

• Continuous arterial pressure monitoring reduces severity and duration of hypotension compared to intermittent monitoring 3, 1, 2
• Administer vasoactive agents targeted to effect rather than fixed doses 1, 2
• Monitor for signs of end-organ hypoperfusion: malaise, lethargy, oliguria, irritability, reduced appetite 3
• When discontinuing vasopressors, gradually decrease dose while expanding blood volume with intravenous fluids to prevent marked hypotension 5