What is the first-line treatment for a patient presenting with hypotension?

First-Line Treatment for Hypotension

Administer intravenous crystalloid fluid bolus (250-500 mL in adults, 10-20 mL/kg in children) while simultaneously initiating norepinephrine as the first-choice vasopressor if hypotension persists after initial fluid challenge, targeting a mean arterial pressure (MAP) of 65 mmHg. 1, 2

Initial Resuscitation Strategy

Fluid Administration

• Begin with crystalloid bolus of 250-500 mL in adults (or 10-20 mL/kg in children) using normal saline or balanced crystalloid solution 1, 2
• For sepsis-induced hypoperfusion specifically, administer at least 30 mL/kg of IV crystalloid within the first 3 hours 3, 1
• For general hypotensive emergencies, give 1-2 L over the first 5 minutes as initial bolus 1

Assess Fluid Responsiveness Before Additional Boluses

• Perform passive leg raise (PLR) test to predict fluid responsiveness—this has 92% specificity and a positive likelihood ratio of 11 1, 2
• Approximately 50% of hypotensive patients are NOT fluid-responsive, making reflexive fluid administration without assessment a critical pitfall to avoid 1, 4
• Use dynamic variables (pulse pressure variation, stroke volume variation) over static variables when available 3, 1

Stop Criteria for Fluid Administration

Terminate fluid resuscitation when any of the following occur:

• Blood pressure normalizes (MAP ≥65 mmHg achieved) 1
• Signs of adequate tissue perfusion present (improved mental status, capillary refill <3 seconds, urine output >0.5 mL/kg/hr, lactate clearance) 1
• Patient develops signs of fluid overload: pulmonary edema, increased jugular venous pressure, new/worsening rales or crackles, oxygen saturation <92% on room air 1, 4

Vasopressor Therapy

First-Line Agent: Norepinephrine

• Norepinephrine is the first-choice vasopressor with strong recommendation and moderate quality evidence 3, 2
• Start norepinephrine when hypotension persists after adequate fluid challenge (systolic BP <90 mmHg or MAP <65 mmHg) 1, 2
• Initial dosing: 8-12 mcg/minute (or 0.02 mcg/kg/min), titrated to achieve MAP ≥65 mmHg 1, 5
• Dilute 4 mg in 1,000 mL of 5% dextrose solution (each mL contains 4 mcg) 5
• Administer through large central vein with continuous monitoring 5

Second-Line Agents

• Add vasopressin (0.03 U/min) if increasing doses of norepinephrine are required 3, 2
• Consider epinephrine (0.05-0.5 mcg/kg/min) as third-line therapy for refractory hypotension 3, 2

Agents to Avoid as First-Line

• Dopamine should only be used in highly selected patients with low risk of tachyarrhythmias and absolute or relative bradycardia 3
• Phenylephrine is NOT recommended except when norepinephrine causes serious arrhythmias, cardiac output is known to be high with persistently low BP, or as salvage therapy 3, 4

Context-Specific Blood Pressure Targets

• Standard target: MAP ≥65 mmHg for most patients 3, 1, 2
• Traumatic brain injury: Maintain MAP ≥80 mmHg to ensure adequate cerebral perfusion pressure 1, 2, 4
• Uncontrolled hemorrhage WITHOUT brain injury: Use permissive hypotension targeting systolic BP 80-90 mmHg until bleeding is controlled 2, 4

Critical Pitfalls to Avoid

• Never delay vasopressor initiation while pursuing aggressive fluid resuscitation in severe hypotension (MAP <50 mmHg)—this increases mortality 2
• Do not continue fluid administration in patients with cardiac dysfunction or volume overload signs despite persistent hypotension—transition to vasopressors instead 1, 4
• Do not use permissive hypotension in traumatic brain injury patients, as cerebral perfusion pressure must be maintained 2, 4
• Avoid using saline solution alone for norepinephrine dilution—must use dextrose-containing solutions to prevent oxidation and loss of potency 5
• Do not abruptly discontinue vasopressor infusion—reduce gradually while expanding blood volume to avoid marked hypotension 5

Special Clinical Scenarios

Anaphylaxis

• Administer epinephrine 0.3-0.5 mg (0.01 mg/kg in children, max 0.3 mg) intramuscularly into deltoid or lateral thigh immediately, repeating every 5 minutes as necessary 2

Cardiogenic Shock

• Start dobutamine at 2-5 mcg/kg/min for low cardiac output states while maintaining blood pressure with norepinephrine 2, 4

Adrenal Crisis

• Administer hydrocortisone 100 mg IV bolus immediately, followed by 50 mg IV every 6 hours or 200 mg continuous infusion 2

Orthostatic Hypotension (Chronic Management)

• Non-pharmacological measures first: exclude exacerbating drugs, increase fluid and salt intake, educate on behavioral strategies 4
• Midodrine is first-line drug (Class I, Level A evidence), dosed individually up to 10 mg two to four times daily 4
• Fludrocortisone is another first-choice drug (Class IIa, Level B evidence), initially 0.05-0.1 mg daily, titrated to 0.1-0.3 mg daily 4