What is the initial evaluation and management of a patient with respiratory distress?

Initial Evaluation of a Patient with Respiratory Distress

Immediately assess severity and initiate oxygen therapy targeting 94-98% saturation (or 88-92% if risk of hypercapnic respiratory failure), while simultaneously determining the underlying cause through focused clinical assessment and objective measurements. 1

Immediate Severity Assessment

Rapidly categorize severity using these objective criteria:

• Mild distress: Dyspnea only with activity, able to speak in full sentences, respiratory rate <25/min, oxygen saturation >90% on room air 1
• Moderate distress: Dyspnea interfering with usual activity, speaking in phrases, respiratory rate 25-35/min, oxygen saturation 85-90% on room air, accessory muscle use 1
• Severe distress: Dyspnea at rest, speaking only in words, respiratory rate >35/min, oxygen saturation <85%, significant accessory muscle use, intercostal retractions 1
• Life-threatening/impending respiratory arrest: Unable to speak, altered mental status, drowsiness, bradypnea or gasping respirations, cyanosis, loss of alertness 1

Initial Oxygen Therapy

Start oxygen immediately before completing full assessment:

• For most patients: Target oxygen saturation 94-98% using nasal cannula (1-6 L/min) or simple face mask (5-10 L/min) 1
• For COPD or chronic hypercapnia risk: Target 88-92% saturation using controlled oxygen delivery (Venturi mask 24-28% or nasal cannula 1-2 L/min) 1
• For severe distress with saturation <90%: Use high-flow nasal cannula, non-rebreather mask (10-15 L/min), or consider non-invasive ventilation 1, 2

Focused Physical Examination

Perform targeted assessment to identify anatomic location of pathology:

Vital signs and general appearance:

• Respiratory rate, heart rate, blood pressure, temperature, oxygen saturation 1
• Level of consciousness, ability to speak, use of accessory muscles, positioning (tripod position suggests severe obstruction) 1

Upper airway assessment:

• Stridor suggests upper airway obstruction requiring immediate ENT/anesthesia consultation 1
• Inability to handle secretions, drooling, muffled voice indicate potential airway emergency 1

Lung auscultation to differentiate causes:

• Wheezing throughout lung fields: bronchospasm from asthma or COPD exacerbation 1
• Crackles/rales: pulmonary edema (cardiac vs. ARDS), pneumonia, or interstitial disease 2, 3
• Unilateral decreased breath sounds: pneumothorax, pleural effusion, or lobar pneumonia 4
• Absent breath sounds with hyperresonance: tension pneumothorax requiring immediate needle decompression 4

Cardiac examination:

• Elevated jugular venous pressure, peripheral edema, S3 gallop suggest cardiogenic pulmonary edema 1
• Signs of right heart strain may indicate pulmonary embolism or cor pulmonale 5

Essential Objective Measurements

Obtain these measurements within the first hour:

• Pulse oximetry: Continuous monitoring; values <90% indicate significant hypoxemia requiring intervention 1
• Peak expiratory flow (PEF) or FEV1 for suspected obstructive disease: <40% predicted indicates severe exacerbation requiring aggressive treatment 1
• Arterial blood gas if severe distress, oxygen saturation <90%, suspected hypercapnia, or altered mental status to assess PaO2, PaCO2, and pH 1

Critical ABG findings requiring immediate action:

• PaCO2 >45 mmHg with pH <7.35 indicates respiratory acidosis; consider non-invasive ventilation 1
• PaO2/FiO2 ratio <300 suggests ARDS; <200 indicates moderate-severe ARDS requiring ICU admission 1, 3
• Rising PaCO2 on repeat measurement despite treatment indicates impending respiratory failure 1

Rapid Diagnostic Testing

Order immediately based on clinical presentation:

• Chest radiograph for all patients except obvious mild asthma exacerbation: identifies pneumonia, pulmonary edema, pneumothorax, pleural effusion 1, 3
• ECG if cardiac cause suspected or age >50: assess for acute coronary syndrome, arrhythmia 1
• Complete blood count: leukocytosis suggests infection 3
• BNP or NT-proBNP if differentiating cardiac vs. non-cardiac pulmonary edema: elevated levels support cardiac etiology 3

Initial Management Based on Suspected Cause

For obstructive airway disease (asthma/COPD):

• Inhaled short-acting beta-agonist (albuterol 2.5-5 mg) via nebulizer every 20 minutes for 3 doses 1, 6
• Add ipratropium bromide 0.5 mg to each nebulizer treatment 1
• Systemic corticosteroids: prednisone 40-60 mg PO or methylprednisolone 125 mg IV 1

For suspected pulmonary edema:

• Diuretics (furosemide 40-80 mg IV) if volume overload present 1
• Nitroglycerin if hypertensive 1
• Non-invasive positive pressure ventilation (CPAP or BiPAP) improves outcomes 1

For suspected pneumonia/ARDS:

• Antibiotics after blood cultures if infectious etiology suspected 3
• Consider corticosteroids for ARDS (dexamethasone 20 mg daily or equivalent) 1
• Prepare for possible intubation if PaO2/FiO2 <150 despite oxygen therapy 1, 2

Reassessment and Escalation Criteria

Reassess at 1 hour after initial treatment:

• Repeat oxygen saturation, respiratory rate, PEF/FEV1, and clinical assessment 1
• Failure to improve or worsening (persistent respiratory rate >30, oxygen saturation <90% on supplemental oxygen, PEF <40% predicted, altered mental status, or rising PaCO2) requires escalation to non-invasive ventilation or intubation 1

Indications for immediate intubation:

• Respiratory arrest or gasping respirations 1
• Severe altered mental status or inability to protect airway 1
• PaCO2 ≥42 mmHg with worsening mental status in asthma exacerbation 1
• Refractory hypoxemia (PaO2 <60 mmHg) despite maximal non-invasive support 1, 2

Critical Pitfalls to Avoid

• Never delay oxygen therapy to obtain arterial blood gas; hypoxemia kills faster than hypercapnia 1
• Do not give excessive oxygen to COPD patients without monitoring; this can worsen hypercapnia and cause respiratory acidosis 1
• Avoid sedatives and anxiolytics in respiratory distress as they suppress respiratory drive 1
• Do not delay intubation once indicated; delayed intubation in deteriorating patients increases mortality 1
• Recognize that normal or rising PaCO2 in an asthmatic indicates severe fatigue and impending respiratory failure, not improvement 1