Acute respiratory failure with Hypoxia and Hypercarbia
COPD exacerbation

Symptoms / Associated Sx

  • Increased dyspnea (beyond baseline), worsening cough

  • Increased sputum production or change in sputum color (purulent = bacterial trigger)

  • Wheezing, chest tightness, accessory muscle use

  • Hypoxia (SpO2 below patient's baseline), tachypnea, tachycardia

  • Hypercapnia with altered mentation (respiratory acidosis — severe)

  • Pursed-lip breathing, barrel chest, hyperresonance on percussion (exam)

Denies

  • Fever + productive cough + focal consolidation (rules out pneumonia as the primary trigger if absent — though may coexist)

  • Orthopnea, PND, bilateral leg edema (rules out CHF as primary cause of dyspnea)

  • Pleuritic chest pain + unilateral absence of breath sounds (rules out pneumothorax)

  • New onset in non-smoker without prior diagnosis (raises alternative diagnoses)

Social History (SHx)

Smoking history (pack-years; current vs. former), occupational exposures (dust, fumes, coal), home oxygen use, prior COPD exacerbations and hospitalizations (frequency predicts future risk), inhaler types and compliance, prior intubations, baseline exercise tolerance and SpO2.

Main Etiology

  • Viral URI (~50%) — rhinovirus most common; influenza, RSV, parainfluenza

  • Bacterial (~25%) — Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae; Pseudomonas in severe COPD (FEV1 <30%, frequent exacerbations, bronchiectasis)

  • Environmental triggers — air pollution, cold air, smoke exposure

  • Medication noncompliance (missed inhalers)

  • No identifiable cause (~25%)

Most Common DDx

  • Acute decompensated heart failure (bilateral crackles + JVD + leg edema + elevated BNP; CXR shows bilateral infiltrates + cardiomegaly; responds to diuresis not bronchodilators)

  • Community-acquired pneumonia (fever + focal consolidation on CXR; elevated WBC/procalcitonin; more than typical COPD sputum change)

  • Pulmonary embolism (acute dyspnea + hypoxia; tachycardia; pleuritic chest pain; D-dimer + CTPA; no wheezing; Wells score)

  • Pneumothorax (sudden onset dyspnea; decreased unilateral breath sounds; tracheal deviation; CXR confirms)

  • Asthma exacerbation (younger patient; atopy; no smoking history; fully reversible obstruction; no emphysematous changes on imaging)

  • Acute respiratory failure from non-COPD cause — ACS with flash pulmonary edema (chest pain + EKG changes + troponin; does not wheeze)

DATA

  • ABG (pH, PaCO2, PaO2 — respiratory acidosis in hypercapnic failure; baseline hypercapnia common in severe COPD)

  • SpO2 and titrated O2 (target SpO2 88–92% — avoid hyperoxia causing hypercapnia in CO2 retainers)

  • CBC (leukocytosis → bacterial trigger)

  • BMP (electrolytes — hypokalemia from beta-agonists; creatinine)

  • BNP/NT-proBNP (rule out CHF)

  • Procalcitonin (guides antibiotic use — >0.1 ng/mL supports bacterial etiology)

  • CXR (infiltrate → pneumonia; hyperinflation, flattened diaphragms; exclude pneumothorax)

  • EKG (cor pulmonale — right heart strain; p-pulmonale; multifocal atrial tachycardia in COPD)

  • Sputum culture (if purulent and hospitalized; guides antibiotic narrowing)

  • Viral respiratory panel (influenza, RSV, COVID-19)

  • Spirometry (not during acute exacerbation — defer to outpatient)

Home Meds

  • SABA (albuterol), SAMA (ipratropium), LABA, LAMA, ICS inhalers — assess compliance and technique

  • Home oxygen (flow rate and hours/day)

  • Systemic steroids if on chronic prednisone (do not abruptly stop)

  • Theophylline (narrow therapeutic index; toxicity risk — check level)

  • Diuretics (if concurrent CHF component)

Plan (COPD add On)

  • scheduled duonebs q4h / albuterol q2 PRN; space as able,

  • PO prednisone 40mg for 5 days; If unable to take PO, give methylprednisolone 40 mg IV daily, then transition to prednisone when able.

  • if infectious trigger suspected -> CTX 1g IV for 5 days , Azithromycin 500mg for three days, (Cefepime 2g (5–7 days) if risk of PsA), On DC Augmentin 875/125 mg BID alone to complete ~5 day

  • Monitoring daily CBC, BMP, tele

  • Bronchopulmonary hygeine: PEP/flutter

  • PT/OT for eval

  • NicWiPP Protocol ADD-ON

  • consider Pulm consult if refractory or in need of Roflumilast (FEV1 < 50%) or Dupilumab (Eso>300)

  • O2 prn to maintain SpO2 88-92%

  • ambulate with Oxygen order prior to DC

  • Resume/optimize maintenance inhalers prior to discharge

  • Smoking cessation counseling

  • BiPAP/NIPPV if hypercapnia, increased WOB, or respiratory acidosis

  • VBG PRN for worsening respiratory status 

Red Flags

  • pH <7.30 + PaCO2 >60 + altered mentation → BiPAP immediately; if fails → intubation

  • Hyperoxia (SpO2 >96%) in COPD → worsens hypercapnia → titrate O2 to 88–92%

  • Failure to improve on BiPAP at 1–2h (pH not improving, worsening mentation) → intubation urgently

  • Multifocal atrial tachycardia (MAT) + COPD → hallmark of severe hypoxemia in COPD; treat underlying COPD not arrhythmia with antiarrhythmics

  • Respiratory arrest or apnea → emergent intubation

Senior IM Resident Pearls

  • GOLD criteria exacerbation severity: Mild = SABA only; Moderate = SABA + antibiotics ± steroids; Severe = hospitalization or ED visit; Very Severe = ICU admission or acute respiratory failure

  • Anthonisen criteria for antibiotics: ≥2 of 3 cardinal symptoms (increased dyspnea, increased sputum volume, increased sputum purulence) → antibiotics reduce exacerbation duration and hospitalization

  • 5-day prednisone is equivalent to 14-day course (REDUCE trial) — use the shorter course; reduces steroid side effects without worse outcomes

  • Hyperoxia causes hypercapnia via Haldane effect (CO2 released from hemoglobin as O2 saturates it) + loss of hypoxic drive; SpO2 target 88–92% is the evidence-based range

  • MAT (multifocal atrial tachycardia) in COPD — multiple P-wave morphologies; do NOT treat with antiarrhythmics; treat the underlying COPD and hypoxemia; verapamil if symptomatic only

  • Common mistake: Giving high-flow O2 to COPD patients with hypercapnia — SpO2 >96% drives CO2 retention; titrate carefully to 88–92%

  • Common mistake: Using corticosteroids for >5 days routinely — REDUCE trial showed non-inferiority of 5-day course; prolonged steroids increase pneumonia risk, hyperglycemia, and muscle wasting

Labs

  • CBC daily

  • BMP daily

  • Mg daily

  • Phos daily

  • VBG/ABG on admission

  • Repeat VBG/ABG PRN worsening respiratory status

  • BNP/NT-proBNP

  • Procalcitonin

  • Respiratory viral panel (COVID/Flu/RSV)

  • Sputum culture if productive sputum

  • Blood cultures x2 if febrile/septic

  • Troponin if chest pain

Imaging

  • CXR portable

  • CT Chest if alternative diagnosis suspected

  • CTA Chest if PE suspected

Respiratory

  • Supplemental O2 to maintain SpO2 88–92%

  • Continuous pulse oximetry

  • Duonebs q4h scheduled

  • Albuterol nebulizer q2h PRN

  • Incentive spirometry

  • PEP/flutter valve therapy

  • RT consult

Steroids

  • Prednisone 40 mg PO daily × 5 days

If unable to take PO:

  • Methylprednisolone 40 mg IV daily

  • Transition to prednisone when able

Antibiotics

Standard coverage:

  • Ceftriaxone 1 g IV q24h × 5 days

  • Azithromycin 500 mg PO/IV daily × 3 days

Pseudomonas risk:

  • Cefepime 2 g IV q8h × 5–7 days

Discharge:

  • Augmentin 875/125 mg PO BID to complete ~5 days total

Monitoring

  • Telemetry

  • Continuous pulse ox

  • Vitals q4h

  • Strict I&O

  • Daily weights

  • Trend CBC/BMP daily

  • Monitor fever curve

BiPAP/NIPPV

Initiate for:

  • Hypercapnia

  • Increased WOB

  • Respiratory acidosis

  • Persistent hypoxia

Escalate:

  • pH <7.30

  • PaCO₂ >60 with worsening mentation

  • Failed BiPAP after 1–2 hrs

  • Respiratory arrest/apnea

Consults

  • RT

  • PT/OT eval and treat

  • Case management

  • Pulmonology PRN

Home Meds

  • Resume maintenance inhalers

  • Verify inhaler compliance

  • Continue home oxygen if indicated

  • Check theophylline level if applicable

DVT PPX

  • Enoxaparin 40 mg SQ daily

OR

  • Heparin 5000 units SQ q8h

If contraindicated:

  • SCDs

Nursing

  • Fall precautions

  • Delirium precautions

  • Aspiration precautions PRN

  • Smoking cessation counseling

  • Ambulate TID

  • Incentive spirometry q1h while awake

Diet

  • Regular diet

  • Cardiac diet if indicated

  • NPO only if concern for intubation

Discharge

  • Ambulatory O2 evaluation

  • Pulmonary rehab referral

  • Ensure LABA/LAMA ± ICS prescribed

  • Inhaler teaching

  • Smoking cessation counseling

  • PCP follow-up within 1 week

  • Pulmonology follow-up if severe COPD

Meds

Home: Trelegy (ICS [fluticasone] / LABA [vilanterol] / LAMA [umeclidinium])  

Inpatient: Dulera (ICS [mometasone] / LABA [formoterol]) + Spiriva (LAMA [tiotropium]) 

ICU: Budesonide (ICS [budesonide]) + scheduled Duoneb (SABA [albuterol] / SAMA [ipratropium], nebulized).

mMRC 0–1 → A

mMRC ≥2 → B

Exacerbations → E