BIOC33H3 Lecture Notes - Asthma, Ranitidine, Orciprenaline
25 Mar 2013
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Document Summary
Chapter 68: respiratory failure and acute respiratory distress syndrome. Respiratory failure results when gas exchange, which involves the transfer of oxygen (o2) and carbon dioxide (co2) between the atmosphere and the blood, is inadequate. Respiratory failure is not a disease; it is a condition that occurs as a result of one or more diseases involving the lungs or other body systems. Respiratory failure can be classified as hypoxemic or hypercapnic: hypoxemic respiratory failure: Commonly defined as a pao2 <60 mm hg when the patient is receiving an inspired o2 concentration >60%. Disorders that interfere with o2 transfer into the blood include pneumonia, pulmonary edema, pulmonary emboli, heart failure, shock, and alveolar injury related to inhalation of toxic gases and lung damage related to alveolar stress/ventilator-induced lung injury. Four physiologic mechanisms may cause hypoxemia and subsequent hypoxemic respiratory failure: (1) mismatch between ventilation and perfusion, commonly referred to as v/q mismatch; (2) shunt; (3) diffusion limitation; and (4) hypoventilation.
