Tracking respiratory therapy in the trauma patient.

The respiratory index (RI), P(AaDO2)/PaO2, was investigated in a retrospective study of 177 intubated patients treated at the Maryland Institute for Emergency Medicine. An RI of 0.1 to 0.37 is normal. Patients with an RI of 2 or greater were intubated. Those patients who reached an RI of 6 or more had an associated 12 per cent probability of survival. The RI reflects the presence of pulmonary shunting in a variety of circumstances including atelectasis, pulmonary contusion, and pulmonary emboli. A nomogram that allows the course of the patient with respiratory problems to be followed is described. Movement along the same isobars or between isobars can be followed by plotting the PaO2 against the FI0-2. Thus, the rationale and effect of respiratory therapeutic manipulations may be recorded graphically.