Chapter 24: Assessment of the Respiratory System

The respiratory system functions through a coordinated sequence beginning with air movement through the upper airway structures including nasal passages, sinuses, pharynx, and larynx, progressing to the lower airways where the trachea branches into progressively smaller bronchi and bronchioles before terminating in alveoli where gas exchange occurs. Oxygen diffuses across the alveolar-capillary membrane into the pulmonary circulation while carbon dioxide moves in the opposite direction for elimination. The chapter emphasizes that adequate oxygenation requires three simultaneous mechanisms: effective ventilation, appropriate diffusion across respiratory membranes, and sufficient pulmonary perfusion. Understanding hemoglobin's oxygen-binding capacity and the oxygen-hemoglobin dissociation curve is critical, as conditions such as fever, acidosis, and elevated carbon dioxide shift the curve rightward to enhance oxygen release to tissues, while alkalosis and hypothermia produce leftward shifts that impair oxygen unloading. Aging significantly alters respiratory mechanics through loss of elastic recoil, diminished alveolar surface area, reduced ciliary clearance, and weakened cough effectiveness, collectively increasing susceptibility to infection and compromising gas exchange efficiency. Health promotion focuses on smoking prevention and cessation using evidence-based strategies like the five-step Ask-Advise-Assess-Assist-Arrange model, alongside assessment of environmental and occupational exposures through systematic tools. The clinical assessment process incorporates detailed history-taking regarding cough characteristics, sputum production, dyspnea, orthopnea, and associated symptoms, followed by systematic physical examination using inspection, palpation, percussion, and auscultation to evaluate respiratory mechanics and identify abnormal findings. Diagnostic modalities including arterial blood gas analysis, imaging studies, pulse oximetry, spirometry, and bronchoscopy provide objective data supporting clinical judgments. Thoracentesis represents both therapeutic and diagnostic intervention requiring specific safety precautions and post-procedure surveillance. Throughout assessment and intervention, nurses must address psychosocial dimensions of respiratory illness, recognizing that breathing difficulties generate anxiety requiring compassionate communication and patient education.