What is the immediate next step in the emergency department workup for a patient with severe weakness, near‑constant diarrhea, worsening shortness of breath and wheezing, recent levofloxacin and amoxicillin‑clavulanate therapy, chronic steroid use, an unknown newly prescribed medication, a known left‑lung mass, and a history of chronic obstructive pulmonary disease exacerbation?

Immediate Emergency Department Workup for Severe COPD Exacerbation with Diarrhea and Weakness

The immediate next step is to obtain arterial blood gas within 60 minutes of arrival while simultaneously initiating controlled oxygen therapy targeting SpO₂ 88-92%, combined nebulized short-acting β₂-agonist plus anticholinergic, and oral prednisone 30-40 mg, followed by urgent assessment for sepsis, electrolyte derangements, and Clostridioides difficile infection. 1

Critical Initial Actions (First 60 Minutes)

Oxygen and Respiratory Assessment

• Initiate controlled oxygen delivery immediately using a Venturi mask (24-28% FiO₂) or nasal cannula (1-2 L/min) targeting SpO₂ 88-92%, as higher concentrations can worsen hypercapnic respiratory failure and increase mortality in COPD patients. 1
• Obtain arterial blood gas within 60 minutes of starting oxygen to assess for hypercapnia (PaCO₂ >45 mmHg) and acidosis (pH <7.35), which would indicate impending respiratory failure. 2, 1
• If pH <7.26 with rising PaCO₂ after initial therapy, prepare for immediate noninvasive ventilation (NIV), as this threshold predicts poor outcome. 2, 1

Immediate Pharmacological Management

• Administer combined nebulized salbutamol 2.5-5 mg plus ipratropium bromide 0.25-0.5 mg immediately upon arrival, as this combination provides superior bronchodilation lasting 4-6 hours compared to either agent alone. 1
• Power nebulizers with compressed air, not oxygen, if the patient appears hypercapnic, and provide supplemental oxygen via nasal cannula (1-2 L/min) concurrently. 2, 1
• Give oral prednisone 30-40 mg immediately (or IV methylprednisolone 40-100 mg if unable to take oral), as systemic corticosteroids improve lung function, oxygenation, and reduce treatment failure by >50%. 1, 3

Urgent Diagnostic Workup (Within First 2 Hours)

Laboratory Assessment for Diarrhea and Weakness

• Obtain comprehensive metabolic panel immediately to assess for hypokalemia, hypomagnesemia, acute kidney injury, and hyperglycemia (from recent steroid use), as severe electrolyte derangements can cause profound weakness and are life-threatening. 2
• Send stool for Clostridioides difficile PCR urgently, given the recent completion of levofloxacin and ongoing augmentin plus steroids—this triple antibiotic/steroid exposure creates extremely high C. difficile risk, and the near-constant diarrhea with weakness is highly suspicious. 1
• Complete blood count to assess for leukocytosis (infection vs. steroid effect) and anemia (chronic disease vs. acute blood loss). 2

Respiratory-Specific Testing

• Chest radiograph immediately to exclude pneumonia, pneumothorax, pulmonary edema, or progression of the known left lung mass, as chest X-ray changes management in 7-21% of COPD exacerbation cases. 1
• Sputum culture if frankly purulent sputum is present, though do not delay antibiotic therapy while awaiting results. 2
• ECG if heart rate <60 or >110 bpm, or if cardiac symptoms present, to exclude arrhythmia or acute coronary syndrome. 1

Sepsis Evaluation

• Blood cultures if fever, hypotension, or altered mental status, as this patient has multiple risk factors for sepsis (age >75, COPD, recent antibiotics, possible C. difficile). 4
• Lactate level to assess for tissue hypoperfusion if sepsis is suspected. 4

Antibiotic Decision Algorithm

Criteria for Antibiotic Initiation

• Prescribe antibiotics for 5-7 days if the patient has increased sputum purulence PLUS either increased dyspnea OR increased sputum volume (two of three cardinal symptoms with purulence being one). 1
• Given this patient's severe presentation with extreme weakness, ongoing dyspnea despite recent levofloxacin, and high-risk features (age, comorbidities, recent hospitalization), antibiotics are strongly indicated. 1

Antibiotic Selection

• First-line choice: Amoxicillin-clavulanate 875/125 mg orally twice daily for 5-7 days, covering Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 1, 5
• However, this patient is already on augmentin (amoxicillin-clavulanate) and recently completed levofloxacin without improvement—this represents treatment failure requiring escalation. 6, 7
• For treatment failure after β-lactam and fluoroquinolone, consider moxifloxacin 400 mg orally once daily for 5 days as a respiratory fluoroquinolone with superior coverage, though monitor for QT prolongation and avoid if C. difficile is confirmed. 6, 8
• Alternative: Doxycycline 100 mg orally twice daily for 5-7 days if fluoroquinolone intolerance or C. difficile concern. 1

Assessment for Respiratory Failure and NIV

Indications for Immediate NIV

• Initiate NIV immediately if pH <7.35 with PaCO₂ >45 mmHg persisting >30 minutes after initial medical therapy, as NIV improves gas exchange, reduces intubation rates by ~50%, shortens hospitalization, and improves survival. 1
• Other NIV indications: persistent hypoxemia despite oxygen, severe dyspnea with accessory muscle use, or respiratory rate >30 breaths/min. 2, 1

Contraindications to NIV

• Confusion with inability to protect airway, large volume of secretions, hemodynamic instability, or recent facial surgery. 1
• If NIV contraindicated or fails, prepare for invasive mechanical ventilation. 2

Addressing the "Unknown New Medication"

Medication Reconciliation Priority

• Contact the discharging hospital pharmacy immediately to obtain the complete discharge medication list, as the unknown medication could be:
  • A newly prescribed long-acting bronchodilator (LAMA/LABA/ICS combination)
  • An anxiolytic (given extreme anxiety)
  • A diuretic (if heart failure was diagnosed)
  • Any of these could interact with current therapy or explain symptoms. 1

Critical Pitfalls to Avoid

Common Errors in This Scenario

• Never administer high-flow oxygen (>28% FiO₂ or >4 L/min) without arterial blood gas monitoring, as this can precipitate hypercapnic respiratory failure and increase mortality. 1
• Do not extend corticosteroids beyond 5 days unless another indication exists—this patient has already been on steroids for 5 days and should not receive more than 5-7 days total. 3
• Do not use intravenous methylxanthines (theophylline/aminophylline), as they increase side effects without added benefit. 1
• Do not delay C. difficile testing in a patient with near-constant diarrhea after multiple antibiotics plus steroids—this is a medical emergency requiring immediate isolation and specific therapy if positive. 1

Weakness and Functional Decline

• The extreme weakness requiring assistance and incontinence suggests either:
  • Severe electrolyte derangement (hypokalemia from β-agonists/steroids)
  • Sepsis with tissue hypoperfusion
  • Severe hypoxemia or hypercapnia
  • C. difficile colitis with dehydration
  • Steroid myopathy (less likely with only 5 days exposure)
• This degree of functional decline mandates hospital admission regardless of respiratory status. 2, 1

Disposition Decision

Criteria Mandating Admission

• This patient meets multiple criteria for hospitalization: marked increase in dyspnea unresponsive to outpatient therapy, extreme weakness, inability to care for self at home, recent treatment failure, age >75, multiple comorbidities, and possible sepsis. 1
• The near-constant diarrhea with incontinence and inability to ambulate safely represents an additional urgent indication for admission. 2

Hospital Orders

• Admit to monitored bed (not ICU unless NIV required or septic shock develops). 1
• Continue nebulized bronchodilators every 4-6 hours for 24-48 hours. 1
• Prednisone 30-40 mg orally once daily for a total of 5 days only (count the days already received). 3
• Controlled oxygen targeting SpO₂ 88-92% with repeat ABG in 60 minutes. 1
• Contact isolation pending C. difficile results. 1
• Aggressive electrolyte repletion as needed. 2
• Home health services should be contacted to cancel Tuesday start and reschedule post-discharge. 1