CSIM2.92 HYPOVENTILATION 1. Also known as respiratory depression occurs when ventilation is inadequate to perform gas exchange. 2. By definition it causes an increased concentration of CO2 (hypercapnia) and respiratory acidosis. 3. Alveolar hypoventilation exists by definitios when arterial PCO2 (PaCO2) increases above the normal range of 37 to 43mmHg, but inclinically importat hypoventilation syndromes PaCO2 is generally in the range of 50-80mmHg. Acute disorders Which represents life-threatening emergencies. Chronic hypoventilation Can result from numerous dx entities but in all cases the underlying mechanism involves a defect in either: The metabolic respiratory control system The respiratory neuromuscular system or The ventilator apparatus

Pathophysiology of hypoventilation in syndromes related to hypoventilationCOPD1. Inhibition of accessory and intercostal muscle breathing2. Shallow breathing during REM sleep3. Increase in upper airway resistance Obesity Central breathing apnea Respiratory neuromuscular disorders Primary alveolar hypoventilation