Initial Physical Assessment of Patients with Respiratory Symptoms
The initial step in physical assessment of a patient with respiratory symptoms is to perform an "ABC" assessment (Airway, Breathing, Circulation) followed immediately by measurement of vital signs including respiratory rate, pulse rate, blood pressure, and oxygen saturation by pulse oximetry. 1
Primary Assessment Sequence
Step 1: ABC Assessment
The first healthcare professional encountering an acutely breathless patient must perform an immediate ABC assessment to identify life-threatening conditions 1:
- Airway: Assess airway patency to ensure it is clear and unobstructed 2
- Breathing: Evaluate work of breathing and measure respiratory rate 2
- Circulation: Palpate pulse rate and rhythm, measure blood pressure 2
Step 2: Vital Signs Measurement
Immediately following the ABC assessment, measure the following vital signs 1:
- Respiratory rate: Essential for detecting respiratory distress 1, 2
- Pulse rate: Required for initial assessment 1
- Blood pressure: Part of core assessment 1
- Oxygen saturation: Must be checked by pulse oximetry in all breathless and acutely ill patients—this is considered the "fifth vital sign" 1
- Temperature: Should be recorded as part of complete vital signs 1
Step 3: Focused Respiratory Examination
After vital signs are obtained, perform targeted physical examination 1, 2:
- Level of consciousness: Assess alertness and mental status (drowsiness may indicate CO2 narcosis) 1
- Work of breathing: Look for use of accessory muscles, paradoxical breathing 1
- Cyanosis: Inspect for bluish discoloration of face, lips, or nails 1
- Wheezing: Auscultate chest, though note that wheezing can be an unreliable indicator of obstruction severity 1
- Fluid status: Assess for signs of volume depletion or overload 1
Target Oxygen Saturation Ranges
The target saturation depends on risk of hypercapnic respiratory failure 1:
- Standard patients: Target 94-98% saturation 1
- COPD or risk of hypercapnia (morbid obesity, cystic fibrosis, chest wall deformities, neuromuscular disorders): Target 88-92% saturation pending blood gas results 1
Critical Pitfalls to Avoid
Never delay oxygen therapy to obtain a room air oximetry reading in patients who clearly require oxygen 1. This is a common error that can worsen patient outcomes.
Do not skip the primary survey and vital signs to jump directly to pulse oximetry or other technology 1. The physical examination and history remain the primary assessment methods, with pulse oximetry serving as an adjunct 1.
Recognize pulse oximetry limitations 1:
- May overestimate oxygen saturation in patients with darker skin pigmentation
- Cannot differentiate carboxyhaemoglobin from oxyhaemoglobin in carbon monoxide poisoning 1
- Affected by poor perfusion, motion, ambient light, and nail polish 1
When to Escalate Assessment
Call for expert assistance early if patients have 1:
- Major life-threatening illness
- Severe respiratory distress with obvious airway compromise
- Oxygen saturation below target despite initial oxygen therapy
- Sudden reduction of ≥3% in oxygen saturation 1
Position matters: Fully conscious hypoxaemic patients should be allowed to maintain an upright posture, as oxygenation is reduced in the supine position 1.