Efficacy of tracheal insufflation of oxygen during oleic acid-induced pulmonary edema.

Study Objectives: To determine whether tracheal insufflation of oxygen (TRIO) might be useful in field resuscitation of casualties with lung dysfunction.
Design: Physiological measurements of cardiac and respiratory function were compared before and after oleic acid lung injury.
Setting and Participants: Beagles were studied in a laboratory.
Interventions: Oleic acid (0.06 mL/kg) was injected over four minutes into the central venous port of a pulmonary artery catheter. Measurements were made during 30 minutes of TRIO before and after acute lung injury.
Measurements: Hemodynamic and respiratory measurements, including intravascular pressures, heart rate, cardiac output, blood gases, respiratory system compliance, and O2 consumption were recorded during conventional mechanical ventilation and TRIO.
Results: Before acute lung injury, PaO2 (mean +/- SD) increased (P less than .05) from 96 +/- 7.4 (13 +/- 1.0 kPa) during conventional mechanical ventilation to 360 +/- 123 mm Hg (48 +/- 16.4 kPa) after TRIO. PaCO2 (mean +/- SD) increased (P less than .05) from 39.5 +/- 1.1 (5.3 +/- 0.1 kPa) to 102 +/- 27.4 mm Hg (13.6 +/- 3.6 kPa). Arterial and mixed venous pH values decreased in proportion to PCO2. After acute lung injury, compliance decreased. PAO2 decreased (P less than .05) to 58 +/- 8.4 mm Hg (7.7 +/- 1.1 kPa) during conventional mechanical ventilation and increased (P less than .05) to 84 +/- 19.6 mm Hg (11.2 +/- 2.6 kPa) after 30 minutes of TRIO.
Conclusion: Despite poor gas exchange after acute lung injury, TRIO maintained adequate oxygenation and may be useful for emergency ventilation even when pulmonary edema complicates resuscitation.