What is the management of scrub typhus (Orientia tsutsugamushi infection) complicated by Acute Respiratory Distress Syndrome (ARDS) and Acute Kidney Injury (AKI)?

Management of Scrub Typhus with ARDS and AKI

Prompt diagnosis and early treatment with doxycycline is the cornerstone of managing scrub typhus complicated by ARDS and AKI, along with appropriate organ support measures.

Diagnosis and Initial Assessment

• Scrub typhus should be considered in patients with fever, varying degrees of respiratory distress, particularly if there is an eschar or history of environmental exposure in endemic areas 1
• Common clinical manifestations include fever (100%), chills (39%), cough (24%), headache (21%), eschar (60%), adenopathy (33%), and rash (21%) 1
• Laboratory abnormalities frequently include anemia (63.2%), leukocytosis (44.3%), thrombocytopenia (61.5%), hyponatremia (35.6%), and hepatic dysfunction (70%) 2
• Assess for complications including pneumonitis (36%), ARDS (15%), acute kidney injury (9%), myocarditis (3%), and septic shock (3%) 1

Antimicrobial Therapy

• Doxycycline is the drug of choice for treating scrub typhus, including cases complicated by ARDS and AKI 3, 4
• Recommended dosage: 100 mg twice daily orally or intravenously for 7-14 days 3
• Early initiation of appropriate antibiotics is critical, as delayed treatment is an independent predictor of ARDS development 5
• Empiric therapy should be started immediately upon clinical suspicion without waiting for serological confirmation 4

Management of ARDS

• Implement lung-protective ventilation strategies with low tidal volumes (6 mL/kg predicted body weight) 6
• Apply sufficient positive end-expiratory pressure (PEEP) to maintain adequate oxygenation 6
• For severe refractory hypoxemia, consider:
  • Prone positioning 6
  • Neuromuscular blockade through continuous infusion (though not routinely recommended) 6
  • Extracorporeal membrane oxygenation (ECMO) in specialized centers for severe cases unresponsive to conventional therapy 6
• Conservative fluid management should be adopted for ARDS patients without tissue hypoperfusion 6
• Consider systemic corticosteroids, which may reduce mortality in ARDS (conditional recommendation, moderate certainty of evidence) 6

Management of AKI

• Record and monitor fluid status by clinical examination and fluid balance daily 6
• Measure serum urea, creatinine, and electrolytes (sodium, potassium, bicarbonate) at least every 48 hours or more often if clinically indicated 6
• Withdraw all nephrotoxic drugs and adjust lactulose dosage if used 6
• Administer fluid challenge using albumin at a dose of 1 g per kilogram of body weight to a maximum of 100 g/day 6
• Monitor for electrolyte abnormalities, particularly hyperkalemia, and manage according to local protocols 6
• Consider renal replacement therapy for severe AKI with:
  • Fluid overload unresponsive to diuretics
  • Severe metabolic acidosis
  • Uremic complications
  • Severe hyperkalemia 6, 2

Supportive Care

• Maintain optimal fluid status (euvolemia) to reduce the incidence of AKI while avoiding fluid overload 6
• Use vasoactive drugs to improve microcirculation if needed 6
• Provide deep vein thrombosis prophylaxis and stress ulcer prevention 6
• Implement appropriate glucose control 6
• Consider enteral nutrition when feasible 6

Monitoring and Follow-up

• Use early warning scores (e.g., NEWS2) for patients with deteriorating clinical condition 6
• Monitor for development of additional complications such as:
  • Meningoencephalitis
  • Gastrointestinal bleeding
  • Disseminated intravascular coagulation
  • Multi-organ failure 2
• Assess need for intensive care support based on severity of organ dysfunction 2

Prognostic Factors and Mortality Risk

• Mortality rate for scrub typhus with ARDS can be as high as 25-37% 2, 5
• Independent predictors of mortality include:
  • ARDS (odds ratio=38.29) and AKI (odds ratio=8.30) 4
  • Hypoalbuminemia, prolonged prothrombin time, and delayed use of appropriate antibiotics 5
  • Advanced age, severe thrombocytopenia, and multi-organ dysfunction 2

Special Considerations

• Recognize that scrub typhus can present as bilateral community-acquired pneumonia resembling atypical pneumonia 4
• The disease shows seasonality, with higher incidence from July to November in some regions 4
• Early recognition of eschar (present in 17-60% of cases) can facilitate prompt diagnosis and treatment 1, 4