What is the appropriate workup for a patient presenting with hypotension?

Workup for Hypotension

The workup for hypotension requires immediate bedside assessment to determine hemodynamic stability, followed by rapid identification of the underlying cause through targeted history, physical examination, and diagnostic testing, with continuous monitoring of vital signs and end-organ perfusion markers. 1, 2

Initial Rapid Assessment

Hemodynamic Stability Determination

• Immediately assess whether the patient is hemodynamically stable or unstable, as unstable patients with end-organ dysfunction (altered mental status, oliguria, cool extremities) require immediate high-acuity care and intervention before completing diagnostic workup. 2
• Measure blood pressure in both arms and obtain orthostatic vital signs (lying for 5 minutes, then standing at 1 and 3 minutes) to identify orthostatic hypotension (≥20 mmHg systolic or ≥10 mmHg diastolic drop). 3, 4

Immediate Bedside Clinical Evaluation

• Perform focused physical examination to categorize the shock type: look for jugular venous distension, sweating, somnolence, and tachycardia suggesting cardiogenic shock 1; warm extremities with low blood pressure indicating vasodilation 2; cold extremities, cyanosis, and decreased mentation suggesting low cardiac output 2; or signs of volume depletion including tachycardia, oliguria, and decreased skin turgor for hypovolemia. 2
• Obtain immediate 12-lead ECG to identify bradycardia, tachyarrhythmias, or acute myocardial infarction as precipitants. 2

Diagnostic Testing

Laboratory Workup

• Draw arterial blood gas and serum lactate immediately as markers of tissue perfusion and shock severity. 1
• Obtain complete blood count, comprehensive metabolic panel including sodium and potassium (to identify hypoaldosteronism), blood urea nitrogen, and creatinine. 3, 5
• Measure troponin if cardiac etiology suspected. 6
• Consider cortisol level and ACTH stimulation test if adrenal insufficiency suspected (hypotension with hyponatremia and hyperkalemia). 5

Imaging Studies

• Perform bedside echocardiography urgently to evaluate left ventricular function, identify mechanical complications, assess volume status, and guide therapy selection. 2
• Obtain chest radiograph to evaluate for pulmonary edema, pneumothorax, or widened mediastinum. 6
• In trauma patients who are hemodynamically stable, perform multi-slice CT (MSCT) for comprehensive evaluation; however, hypotensive patients (systolic BP <90 mmHg) with free intra-abdominal fluid on ultrasound should proceed directly to surgery if unstable despite fluid resuscitation. 3
• Use bedside ultrasound (FAST exam) in trauma or suspected intra-abdominal bleeding to rapidly identify free fluid. 3

Continuous Monitoring Requirements

Vital Sign Monitoring

• Continuously monitor ECG, blood pressure, oxygen saturation, and urine output for at least the first 24 hours. 3, 1
• Measure fluid intake and output, daily weights, and jugular venous pressure to evaluate volume status. 3
• Monitor serum lactate and central venous oxygen saturation (SvO2) as markers of treatment response. 1

Advanced Hemodynamic Monitoring

• Consider intra-arterial line placement only in patients with persistent hypotension despite treatment for continuous blood pressure monitoring. 3
• Pulmonary artery catheterization should be reserved for select patients: those refractory to pharmacological treatment, persistently hypotensive, with uncertain left ventricular filling pressure, or being considered for cardiac surgery. 3
• Use non-invasive cardiac output monitoring or bedside echocardiography to guide therapy selection when etiology remains unclear. 2

Cause-Specific Diagnostic Considerations

Cardiogenic Shock

• The presence of hypotension with tachycardia, jugular venous distension, and pulmonary congestion (Killip class 4) suggests cardiogenic shock requiring urgent echocardiography to determine etiology. 1
• Evaluate for acute coronary syndrome with serial troponins and ECG. 6

Hypovolemic Shock

• Perform passive leg raise (PLR) test to assess fluid responsiveness: if PLR corrects hypotension, the patient may benefit from fluid administration; approximately 50% of hypotensive patients are NOT fluid-responsive, making reflexive fluid administration potentially harmful. 2

Distributive Shock

• Consider sepsis workup with blood cultures, urinalysis, and imaging for infection source if warm extremities with low blood pressure. 2
• Evaluate for anaphylaxis, adrenal insufficiency, or medication effects. 5, 7

Obstructive Shock

• Obtain CT pulmonary angiography if massive pulmonary embolism suspected. 1
• Echocardiography can identify pericardial tamponade or tension pneumothorax. 2

Critical Pitfalls to Avoid

• Do not rely on single hematocrit measurements as an isolated marker for bleeding, as initial hematocrit has low sensitivity (0.5) for detecting traumatic hemorrhage requiring surgical intervention due to confounding from resuscitative measures. 3
• Avoid reflexive fluid administration without PLR testing in non-hypovolemic patients, as this worsens outcomes. 2
• Do not delay imaging for transport in unstable patients; bedside ultrasound is preferred over CT in hemodynamically unstable trauma patients. 3
• Ensure close monitoring during any transport to imaging, with continuation of resuscitation measures. 3