How to manage a 26-year-old female with tachycardia, fever, palpitations, and metabolic acidosis, with a history of Oral Contraceptive Pill (OCP) intake and a normal Electrocardiogram (ECG)?

Management of a 26-Year-Old Female with Tachycardia, Fever, Palpitations, and Metabolic Acidosis

For a 26-year-old female with tachycardia (150 bpm), fever, palpitations, metabolic acidosis, normal ECG, and history of OCP use, immediate evaluation should focus on identifying the underlying cause of tachycardia while addressing metabolic acidosis, with special consideration for potential thromboembolic events due to OCP use.

Initial Assessment and Management

• First determine hemodynamic stability - if unstable (hypotension, altered mental status, signs of shock), immediate synchronized cardioversion is recommended 1
• If hemodynamically stable, proceed with the following diagnostic workup:

Immediate Diagnostic Steps

• Complete 12-lead ECG analysis to confirm normal findings and rule out pre-excitation patterns 1
• Blood tests including:
  • Complete blood count to assess for infection 1
  • Comprehensive metabolic panel to evaluate electrolytes 2
  • Anion gap calculation to classify metabolic acidosis (normal vs. elevated anion gap) 2, 3
  • Lactate level to assess tissue perfusion 4, 5
  • Thyroid function tests to rule out hyperthyroidism as cause of sinus tachycardia 1
  • Blood cultures if infectious etiology is suspected 4
• Chest X-ray to evaluate for pulmonary pathology 1
• Echocardiogram to exclude structural heart disease 1

Management of Tachycardia

If the patient remains hemodynamically stable with narrow complex tachycardia:

• Try vagal maneuvers (Valsalva, carotid sinus massage) as first-line intervention 1
• If unsuccessful, administer adenosine IV (6mg initially, followed by 12mg if needed) 1
• For persistent tachycardia, consider IV beta-blockers, diltiazem, or verapamil 1
• If pharmacological therapy fails, synchronized cardioversion is recommended 1

Evaluation of Metabolic Acidosis

• Calculate serum anion gap: [Na+] - ([HCO3-] + [Cl-]) 2, 3
• For elevated anion gap acidosis:
  • Rule out lactic acidosis due to tissue hypoperfusion or sepsis 4, 5
  • Consider toxic ingestions (especially with OCP use history) 6
• For normal anion gap (hyperchloremic) acidosis:
  • Evaluate renal function and urinary pH 3
  • Consider renal tubular acidosis or gastrointestinal bicarbonate loss 2

Special Considerations with OCP History

• Evaluate for possible thromboembolic complications:
  • D-dimer testing 1
  • Consider CT pulmonary angiogram to rule out pulmonary embolism if clinically suspected 1
  • Lower extremity ultrasound if deep vein thrombosis is suspected 1

Treatment of Metabolic Acidosis

• Address the underlying cause rather than just treating the acidosis 2, 5
• Provide supportive care with IV fluids for volume resuscitation if indicated 4
• Consider sodium bicarbonate administration only for severe acidosis (pH < 7.1) 5
• If lactic acidosis is present, focus on improving tissue perfusion 4, 5

Disposition and Follow-up

• Admission for further monitoring and management is warranted given the combination of tachycardia, fever, and metabolic acidosis 1
• Consider referral to a cardiac arrhythmia specialist if tachycardia persists despite initial management 1
• If no clear etiology is identified with initial testing, consider additional investigations such as CT imaging or invasive electrophysiological studies 1

Potential Pitfalls

• Do not assume sinus tachycardia is solely due to fever - thoroughly investigate for underlying causes 1
• Avoid calcium channel blockers if pre-excitation syndrome is suspected 1
• Do not delay treatment of severe metabolic acidosis while awaiting complete diagnostic workup 5
• Remember that OCP use increases risk of thromboembolic events which could explain both tachycardia and metabolic acidosis 1