![]() Imaging studies are helpful in assessing disease severity and the extent of possible complications. Diagnosis is primarily based on clinical presentation and pulmonary function tests ( PFTs), which typically show a decreased ratio of forced expiratory volume ( FEV) to forced vital capacity ( FVC). Clinical features include dyspnea and productive cough and, in later stages, tachypnea, tachycardia, and cyanosis. ![]() These changes cause a loss of diffusion area, which can lead to inadequate oxygen absorption ( hypoxemia) and CO 2 release ( hypercapnia). COPD begins with chronic airway inflammation, which usually progresses to emphysema, a condition that is characterized by irreversible bronchial narrowing and alveolar hyperinflation. Some individuals are genetically predisposed to COPD, particularly those with α 1-antitrypsin deficiency ( AATD). It is predominantly caused by inhaled toxins (e.g., tobacco smoke or air pollution). Positive pressure ventilation (i.e.Chronic obstructive pulmonary disease (COPD) is characterized by chronic respiratory symptoms resulting from airflow obstruction and alveolar gas exchange abnormalities.Neck extension and jaw protrusion (can increase it twofold).General anesthesia – multifactorial, including loss of skeletal muscle tone and bronchoconstrictor tone.The ratio of physiologic dead space to tidal volume is usually about 1/3. Alveolar dead space is the volume of gas within unperfused alveoli (and thus not participating in gas exchange either) it is usually negligible in the healthy, awake patient. Anatomic dead space is the volume of gas within the conducting zone (as opposed to the transitional and respiratory zones) and includes the trachea, bronchus, bronchioles, and terminal bronchioles it is approximately 2 mL/kg in the upright position. ![]() Physiologic or total dead space is the sum of anatomic dead space and alveolar dead space. Dead space is the volume of a breath that does not participate in gas exchange. ![]()
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