An elderly cachectic patient with chronic obstructive pulmonary disease and bronchiectasis who has a new pseudomonal pneumonia and recent thoracentesis now has an elevated International Normalized Ratio, low fibrinogen, undetectable haptoglobin, a negative Coombs test, and chronic thrombocytopenia of 66 ×10⁹/L; what is the most likely diagnosis and appropriate initial management?

Disseminated Intravascular Coagulation (DIC) Secondary to Pseudomonal Pneumonia with Underlying Chronic Lung Disease

This cachectic COPD/bronchiectasis patient with pseudomonal pneumonia presenting with elevated INR, low fibrinogen (125 mg/dL), undetectable haptoglobin, negative Coombs test, and chronic thrombocytopenia (66 × 10⁹/L) most likely has disseminated intravascular coagulation (DIC) triggered by severe bacterial sepsis.

Diagnostic Reasoning

DIC as the Primary Diagnosis

• The constellation of coagulopathy (elevated INR), consumptive thrombocytopenia, low fibrinogen, and undetectable haptoglobin in the setting of severe pseudomonal pneumonia strongly suggests DIC. Among septic patients, DIC develops when bacterial endotoxins trigger widespread activation of the coagulation cascade, leading to consumption of clotting factors and platelets 1.

• Low fibrinogen (125 mg/dL, normal >150 mg/dL) is a hallmark of DIC, reflecting consumption of this critical clotting factor during widespread microvascular thrombosis 1, 2.

• Undetectable haptoglobin with a negative Coombs test indicates intravascular hemolysis from microangiopathic hemolytic anemia (MAHA), a common feature of DIC where red blood cells are sheared by fibrin strands in small vessels 2, 3.

• The thrombocytopenia of 66 × 10⁹/L, while noted as "not new," is consistent with platelet consumption in DIC, particularly in a patient with chronic lung disease who may have baseline mild thrombocytopenia 1, 2.

Severe Pseudomonal Pneumonia as the Trigger

• Pseudomonas aeruginosa pneumonia in COPD/bronchiectasis patients is associated with severe systemic inflammation and high mortality, making it a well-recognized trigger for DIC 1, 4.

• Bronchiectasis is common in COPD patients (prevalence 43.7% in one study) and predisposes to chronic Pseudomonas colonization and recurrent severe exacerbations 5, 4, 6, 7.

• The combination of cachexia, chronic lung disease, and pseudomonal infection creates a perfect storm for sepsis-induced DIC, as malnutrition impairs immune function and wound healing 5, 4.

Distinguishing DIC from Isolated Liver Dysfunction

• While elevated INR can reflect liver synthetic dysfunction, the presence of low fibrinogen and undetectable haptoglobin points away from isolated liver disease and toward DIC 2, 3.

• In acute liver failure, INR ≥1.5 with hepatocellular injury defines the condition, but fibrinogen is typically preserved or only mildly reduced until very late stages 2.

• The INR in this patient should not be interpreted as a bleeding predictor or trigger for plasma transfusion, as INR was designed only for warfarin monitoring and is unreliable in non-warfarin coagulopathy 3.

Immediate Management Priorities

Critical Care and Monitoring

• Transfer to ICU immediately for hourly neurological assessments and aggressive infection surveillance, as DIC can progress rapidly to multiorgan failure 2.

• Measure PT/INR, fibrinogen, D-dimer, and platelet count every 12–24 hours to track disease trajectory and guide transfusion decisions 2, 3.

• Obtain blood cultures before escalating antibiotics to enable pathogen-directed therapy, though antibiotic administration must not be delayed 1, 8.

Antimicrobial Therapy for Pseudomonal Pneumonia

• For hospitalized non-ICU patients with documented Pseudomonas risk factors (bronchiectasis, chronic lung disease), use piperacillin-tazobactam 4.5 g IV every 6 hours PLUS ciprofloxacin 400 mg IV every 8 hours (or levofloxacin 750 mg IV daily) PLUS an aminoglycoside (gentamicin 5–7 mg/kg IV daily) for dual antipseudomonal coverage 1, 8.

• If the patient meets ICU criteria (septic shock, respiratory failure, or ≥3 minor severity criteria), escalate to ceftriaxone 2 g IV daily PLUS azithromycin 500 mg IV daily PLUS antipseudomonal agents as above 1, 8.

• Administer the first antibiotic dose immediately in the emergency department, as delays beyond 8 hours increase 30-day mortality by 20–30% 1, 8.

Coagulation Management in DIC

• Do NOT transfuse fresh frozen plasma (FFP) solely to "correct" the INR in the absence of active bleeding, as prophylactic plasma transfusion offers no benefit and may worsen portal hypertension if underlying liver disease exists 2, 3.

• Transfuse cryoprecipitate to maintain fibrinogen >1.5 g/L (150 mg/dL) if the patient has active bleeding or requires an invasive procedure 2.

• Platelet transfusion thresholds in DIC are <50 × 10⁹/L for active bleeding and <25 × 10⁹/L for invasive procedures; the current platelet count of 66 × 10⁹/L does not mandate transfusion without bleeding 2.

• Avoid prophylactic platelet transfusion in stable patients, as randomized trials show no reduction in bleeding and unnecessary transfusions add risk 2, 3.

Addressing the Underlying Sepsis

• Aggressive source control is paramount: ensure adequate drainage if pleural effusion or empyema develops, as delayed drainage increases mortality 1, 2.

• Monitor for acute kidney injury (AKI) with serial creatinine measurements, as AKI frequently complicates severe sepsis and worsens prognosis 2.

• Implement aggressive infection surveillance with daily blood cultures if fever persists, as neutrophilic vacuoles (if present on smear) may signal early bacterial infection 2.

Duration of Antimicrobial Therapy

• Treat pseudomonal pneumonia for a minimum of 14–21 days, as Pseudomonas aeruginosa requires extended courses compared to typical community-acquired pneumonia 1, 8.

• Continue antibiotics until the patient is afebrile for 48–72 hours with no more than one sign of clinical instability (temperature ≤37.8°C, heart rate ≤100 bpm, respiratory rate ≤24 breaths/min, systolic BP ≥90 mmHg, SpO₂ ≥90% on room air) 1, 8.

• Switch from IV to oral antibiotics only when hemodynamically stable, clinically improving, and able to tolerate oral intake—typically by hospital day 2–3 for uncomplicated cases, but likely longer in this patient with DIC 1, 8.

Long-Term Management of COPD/Bronchiectasis with Pseudomonas

• Consider long-term inhaled antibiotics (colistin or gentamicin) or oral macrolides (azithromycin) if the patient experiences ≥3 exacerbations per year after recovery from this acute episode 1, 4.

• Ensure airway clearance techniques, pulmonary rehabilitation, and inhaled bronchodilators are optimized to reduce future exacerbation risk 1, 4.

• Address malnutrition aggressively with nutritional supplementation, as cachexia impairs immune function and wound healing 5, 4.

Critical Pitfalls to Avoid

• Do NOT delay ICU transfer while awaiting clinical decline; early intensive monitoring is critical in DIC 2.

• Do NOT transfuse plasma solely to normalize INR in non-bleeding patients, as this offers no benefit and may worsen outcomes 2, 3.

• Do NOT underestimate infection risk in DIC; neutrophilic vacuoles (if present) justify prompt and thorough infectious work-up 2.

• Do NOT use standard community-acquired pneumonia regimens (ceftriaxone + azithromycin) without adding antipseudomonal coverage in patients with documented Pseudomonas risk factors 1, 8.

• Do NOT postpone antibiotic administration to obtain cultures; specimens should be collected rapidly, but therapy must not be delayed 1, 8.