Inverse ratio ventilation (I/E = 2/1) in acute respiratory distress syndrome: a six-hour controlled study.

Abstract

To assess the cardiorespiratory effects of a prolonged application of inverse ratio ventilation (IRV), we compared IRV (I/E = 2) with conventional ventilation (CV) (I/E = 0.5), applied for 6 h each in a randomized order, with constant tidal volume (VT) and total positive end-expiratory pressure (PEEP(tot)) in eight patients with acute respiratory distress syndrome (ARDS). After 1 h, IRV resulted in a lower peak inspiratory pressure (PIP) (28.2 +/- 1.5 versus 35.6 +/- 1.7 cm H2O, p < 0.05), an unchanged plateau pressure, and a higher mean airway pressure (MAP) (17.8 +/- 0.8 versus 15.6 +/- 0.5 cm H2O, p < 0.05) than CV. No significant difference in Pa(O2) and shunt fraction (QS/QT) was observed (83 +/- 7 mm Hg and 40 +/- 4% in CV versus 92 +/- 14 mm Hg and 35 +/- 3% in IRV, respectively). The Pa(CO2) was lower in IRV (48 +/- 3 versus 55 +/- 5 mm Hg, p < 0.05). Cardiac index (CI) and oxygen delivery (D(O2)) were lower in IRV (3.7 +/- 0.4 L/min/m2 and 500 +/- 61 ml/min/m2 versus 4.6 +/- 0.5 L/min/m2 and 617 +/- 80 ml/min/m2, respectively, p = 0.05 for both). Regardless of the considered parameter, no significant difference was observed between results after 1, 2, 4, and 6 h in each mode. We conclude that IRV at a ratio that results in a significant intrinsic PEEP does not improve Pa(O2), enhances CO2 elimination, decreases cardiac output (CO), and does not exert any time-dependent effect.

• Authors: A Mercat, M Titiriga, N Anguel, C Richard, J L Teboul
• Journal: American journal of respiratory and critical care medicine (Am J Respir Crit Care Med) Vol. 155 Issue 5 Pg. 1637-42 (May 1997) ISSN: 1073-449X [Print] United States
• PMID: 9154869 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial)

Chemical References

• Oxygen

Topics

• Adult
• Aged
• Blood Pressure
• Cardiac Output
• Cross-Over Studies
• Female
• Humans
• Male
• Middle Aged
• Oxygen (blood)
• Oxygen Consumption
• Positive-Pressure Respiration
• Prospective Studies
• Pulmonary Artery (physiopathology)
• Respiration, Artificial (methods)
• Respiratory Distress Syndrome (physiopathology, therapy)
• Tidal Volume
• Time Factors