What are the potential causes of hypotension with a blood pressure of 107/37 mmHg, a mean arterial pressure (MAP) of 59 mmHg, and a heart rate (HR) of 74 beats per minute?

Differential Diagnosis of Wide Pulse Pressure Hypotension

This blood pressure pattern (107/37 mmHg with MAP 59 mmHg and HR 74 bpm) represents a critically wide pulse pressure (70 mmHg) with severe diastolic hypotension, most commonly caused by aortic regurgitation, but also seen in high-output states, severe sepsis with vasodilation, or endocrine disorders—immediate assessment must focus on determining whether this reflects vasodilatory shock, valvular pathology, or a high cardiac output state. 1

Immediate Clinical Assessment Priority

The first critical step is determining the underlying physiological derangement causing this specific hemodynamic pattern, as treatment differs fundamentally based on etiology 1:

• Assess organ perfusion immediately rather than focusing solely on the blood pressure number—look for altered mentation, cold extremities, livedo reticularis, urine output <30 mL/h, or lactate >2 mmol/L 2
• MAP of 59 mmHg is below the critical threshold of 65 mmHg required for adequate tissue perfusion in most patients, though hypotension does not always correlate with impaired perfusion 2
• The relatively normal heart rate (74 bpm) with severe hypotension suggests this is not primarily a hypovolemic or cardiogenic process, as compensatory tachycardia would be expected 1

Primary Differential Diagnoses

Vasodilatory Causes (Most Likely)

Severe vasodilation is the most probable cause given the wide pulse pressure with preserved systolic pressure but critically low diastolic pressure:

• Septic shock with systemic vasodilation—the low diastolic pressure reflects loss of systemic vascular resistance while cardiac output may be preserved or elevated 2, 1
• Medication-induced vasodilation—particularly ACE inhibitors, ARBs (sartans), calcium channel blockers, or alpha-blockers can cause refractory hypotension with this pattern 2, 3
• Anaphylaxis—acute systemic vasodilation with preserved or elevated cardiac output 1

Valvular Pathology

Acute or chronic aortic regurgitation creates the classic wide pulse pressure pattern:

• Diastolic runoff through incompetent aortic valve causes severely low diastolic pressure 2
• Echocardiography is essential to assess for valvular dysfunction and should be performed urgently 2

High Cardiac Output States

• Thyrotoxicosis—increased metabolic demand with high cardiac output and low systemic vascular resistance 4
• Severe anemia—compensatory high cardiac output with reduced viscosity 5
• Arteriovenous fistula or shunt—pathologic low-resistance circuit 5

Endocrine Disorders

• Adrenal insufficiency—presents with hypotension, though typically with lower systolic pressures as well 4
• Pheochromocytoma (paradoxical)—rare presentation during catecholamine depletion phase 4

Immediate Diagnostic Workup

Perform these assessments simultaneously while initiating treatment:

• Passive leg raise (PLR) test with hemodynamic monitoring—88% sensitivity and 92% specificity for fluid responsiveness; if positive, consider fluid bolus, but if negative, proceed directly to vasopressor support 3, 1
• Echocardiography at bedside to evaluate for aortic regurgitation, left ventricular function, and stroke volume 2
• Lactate measurement—if elevated >2 mmol/L, indicates tissue hypoperfusion requiring aggressive resuscitation 2, 6
• Review medication list immediately—discontinue or hold ACE inhibitors, ARBs, calcium channel blockers, alpha-blockers, or other vasodilators 2, 3
• Assess for sepsis—obtain cultures, initiate broad-spectrum antibiotics within one hour if sepsis suspected 6

Treatment Algorithm

If Vasodilation is Confirmed (Most Common)

Norepinephrine is the first-line vasopressor for vasodilatory hypotension 1, 7:

• Target MAP ≥65 mmHg initially 2, 1
• Start norepinephrine infusion immediately if MAP remains <65 mmHg despite initial measures 1, 6
• Phenylephrine is preferred if tachycardia is present (though HR is 74 in this case), as it induces reflex bradycardia 3
• If hypotension is refractory to conventional vasopressors and patient is on sartans/ACE inhibitors, vasopressin or analogs are highly effective for sartan-induced vasodilation 3

If Hypovolemia is Contributing

• Administer 500 mL crystalloid bolus (lactated Ringer's preferred) only if PLR test is positive 3, 1
• Reassess hemodynamics after each bolus—do not continue fluid administration if no response 1
• Avoid reflexive fluid administration without assessing fluid responsiveness, as approximately 50% of hypotensive patients are not hypovolemic 1

If Aortic Regurgitation is Identified

• Avoid excessive bradycardia—maintain heart rate to allow adequate diastolic filling time without prolonging diastolic runoff 2
• Vasodilators may paradoxically improve forward flow by reducing afterload, but this requires careful titration with invasive monitoring 2
• Urgent cardiology/cardiac surgery consultation for severe acute AR 2

If High-Output State is Present

• Treat underlying cause (thyrotoxicosis, anemia, AV fistula) 4
• Beta-blockers may be beneficial for thyrotoxicosis to reduce heart rate and cardiac output 4

Monitoring and Escalation

• Continuous arterial blood pressure monitoring is strongly recommended to reduce severity and duration of hypotension 1
• Measure blood pressure every 15 minutes if continuous monitoring unavailable 3
• Remeasure lactate within 2-6 hours if initially elevated—target clearance of at least 10% every 2 hours 6
• Consider ICU admission given MAP <65 mmHg, which defines inadequate perfusion requiring intensive monitoring 6

Critical Pitfalls to Avoid

• Do not rely on CVP alone to guide fluid management—the Surviving Sepsis Campaign explicitly states CVP can no longer justify fluid decisions 2, 6
• Do not administer aggressive fluids without confirming fluid responsiveness—this can worsen outcomes in non-hypovolemic patients 1
• Do not ignore medication review—sartan/ACE inhibitor-induced hypotension requires specific management with vasopressin analogs 3
• Do not assume hypotension equals hypoperfusion—assess end-organ function directly through lactate, urine output, and mental status 2, 5
• A systolic BP <80 mmHg or MAP <65 mmHg for >15 minutes warrants immediate escalation of care and consideration of continuous hemodynamic monitoring 3, 8