| Abstract: | A sheet to chart the clinical respiratory variables relevant to acute respiratory insufficiency (ARI) therapy is presented. The chart permits plotting shunt fraction (Qsp/Qt) and efficiency (E or 1--Qsp/Qt) vs. load (L). L is the volume of oxygen (combined and dissolved) that would be exchanged in the lung per minute, if venous blood became fully equilibrated with alveolar gas. L relates cardiac output (Qt), hemoglobin concentration, alveolar oxygen tension, venous oxygen saturation and tension, and the oxygen-hemoglobin combining and oxygen solubility constants. Oxygen consumption (VO2) isopleths are added to the sheet (VO2 = L X E). Qt, VO2, and hence L are indexed per m2 (body surface area), and the approximate normal VO2 range is indicated. Using this sheet hopefully simplifies the correlation of complex pulmonary oxygen exchange data and enhances information recognition and analysis. It provides special help in determining the optimal PEEP in difficult ARI cases. To illustrate its use, a case is detailed. |
