Final answer:
Percussing diaphragmatic excursion on the posterior thorax involves marking the levels of diaphragmatic dullness at full expiration and full inspiration, then measuring the distance between them to evaluate diaphragm movement during respiration.
Step-by-step explanation:
The process of evaluating diaphragmatic excursion involves the assessment of diaphragm movement during respiration. During normal breathing, the contraction and relaxation of the diaphragm, along with the movement of intercostal muscles, create changes in thoracic cavity volume, affecting the pressure and thus allowing for the flow of air in and out of the lungs. The diaphragm dome-shaped at rest and it moves downwards during inspiration and upwards during expiration.
Percussion Technique:
- The patient is asked to exhale fully and hold their breath while the healthcare professional percusses down the posterior thorax, marking the point where resonance (a hollow sound produced by tapping over a part of the body) changes to dullness (a thud-like sound). This indicates the level of the diaphragm at full expiration.
- Next, the patient is asked to take a deep breath and hold it. The healthcare professional then percusses upward from the mark of full expiration until the change from dullness back to resonance is noted, indicating the level of the diaphragm at full inspiration.
- The distance between the two marks represents the diaphragmatic excursion, which is usually about 3-5 centimeters in a healthy adult but can vary depending on individual circumstances.
This non-invasive assessment is valuable for evaluating diaphragmatic function and detecting any potential abnormalities indicating respiratory issues such as emphysema, phrenic nerve paralysis, or other conditions that may impair diaphragmatic movement.