Evidence-Based Assessment of the Lungs and Respiratory System

• Clubbing: An increased angle between the proximal nail fold and the nail plate, which serves as a clinical manifestation of chronic tissue hypoxia.
• Barrel Chest: A rounded chest appearance often associated with hyperinflation of the lungs seen in patients with Chronic Obstructive Pulmonary Disease (COPD).
• Pectus Excavatum: A congenital condition where the anterior chest wall is sunken or depressed.

Palpation

Once inspection is complete, move to palpation to assess tactile sensations and movement:

• Chest Expansion: With the patient sitting or standing, place hands on the posterior thorax near the diaphragm with thumbs touching the midline. Ask the patient to take a deep breath to assess for symmetric expansion.
• Tactile Fremitus: Using the ulnar aspect of the hands or the bony aspects of the fingers, feel for vibrations transmitted through the chest wall while the patient speaks.

Physical Examination: Percussion and Auscultation

Percussion Technique

Percussion involves using a quick, sharp wrist motion to strike a "plexor" finger against the patient's skin to produce sound. This allows the clinician to map out lung density across different landmarks:

• Anterior: Avoid percussing directly over breast tissue.
• Posterior: Best performed with the patient seated and head bent forward.
• Lateral: Ask the patient to raise their arms to access these areas.

Auscultation

Auscultation is the process of listening to breath sounds using the diaphragm of a stethoscope placed directly on the skin. The clinician should instruct the patient to take deep breaths through an open mouth and listen to at least one full breath cycle at every site.

Diagnostic Monitoring and Lung Function

To supplement the physical exam, several objective tools are used to monitor respiratory status and airflow.

Vital Signs and Flow Measurement

• Pulse Oximetry: A noninvasive external device that uses a sensor (usually on a finger or toe) to measure the oxygen saturation of arterial blood.
• Peak Flow Meter: A handheld device used to measure peak expiratory flow—the maximum volume of air exhaled quickly after a deep inspiration. This is particularly useful in managing asthma, as values correlate with airflow limitations and are adjusted based on the patient's age and height.

Spirometry and Pulmonary Function Tests (PFTs)

Spirometry is a more advanced form of pulmonary function testing. It utilizes flow-volume loops (spirograms) to provide a visual representation of lung function. These loops allow clinicians to differentiate between:

1. Normal lung function.
2. Obstructive diseases (e.g., asthma, where airflow is limited).
3. Restrictive diseases (where lung expansion is limited).

Clinical Note: Pediatric Respiratory Distress When assessing infants and young children, be alert for population-specific signs of distress, including nasal flaring, grunting, head bobbing, or stridor.

By combining these history-taking skills, physical maneuvers, and diagnostic technologies, clinicians can develop a comprehensive and evidence-based understanding of a patient's respiratory health.