Tidal volume lower than 6 ml/kg enhances lung protection: role of extracorporeal carbon dioxide removal

Anesthesiology. 2009 Oct;111(4):826-35. doi: 10.1097/ALN.0b013e3181b764d2.

Abstract

Background: Tidal hyperinflation may occur in patients with acute respiratory distress syndrome who are ventilated with a tidal volume (VT) of 6 ml/kg of predicted body weight develop a plateau pressure (PPLAT) of 28 < or = PPLAT < or = 30 cm H2O. The authors verified whether VT lower than 6 ml/kg may enhance lung protection and that consequent respiratory acidosis may be managed by extracorporeal carbon dioxide removal.

Methods: PPLAT, lung morphology computed tomography, and pulmonary inflammatory cytokines (bronchoalveolar lavage) were assessed in 32 patients ventilated with a VT of 6 ml/kg. Data are provided as mean +/- SD or median and interquartile (25th and 75th percentile) range. In patients with 28 < or = PPLAT < or = 30 cm H2O (n = 10), VT was reduced from 6.3 +/- 0.2 to 4.2 +/- 0.3 ml/kg, and PPLAT decreased from 29.1 +/- 1.2 to 25.0 +/- 1.2 cm H2O (P < 0.001); consequent respiratory acidosis (Paco2 from 48.4 +/- 8.7 to 73.6 +/- 11.1 mmHg and pH from 7.36 +/- 0.03 to 7.20 +/- 0.02; P < 0.001) was managed by extracorporeal carbon dioxide removal. Lung function, morphology, and pulmonary inflammatory cytokines were also assessed after 72 h.

Results: Extracorporeal assist normalized Paco2 (50.4 +/- 8.2 mmHg) and pH (7.32 +/- 0.03) and allowed use of VT lower than 6 ml/kg for 144 (84-168) h. The improvement of morphological markers of lung protection and the reduction of pulmonary cytokines concentration (P < 0.01) were observed after 72 h of ventilation with VT lower than 6 ml/kg. No patient-related complications were observed.

Conclusions: VT lower than 6 ml/Kg enhanced lung protection. Respiratory acidosis consequent to low VT ventilation was safely and efficiently managed by extracorporeal carbon dioxide removal.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acidosis, Respiratory / therapy
  • Aged
  • Air Pressure
  • Carbon Dioxide / blood
  • Carbon Dioxide / isolation & purification*
  • Cardiac Output / physiology
  • Cytokines / blood
  • Extracorporeal Membrane Oxygenation*
  • Female
  • Humans
  • Hydrogen-Ion Concentration
  • Lung / diagnostic imaging
  • Lung / pathology
  • Lung Diseases / pathology
  • Lung Diseases / prevention & control*
  • Male
  • Middle Aged
  • Pneumonia / pathology
  • Positive-Pressure Respiration
  • Respiration, Artificial / adverse effects
  • Respiratory Distress Syndrome, Adult / therapy
  • Respiratory Function Tests
  • Tidal Volume / physiology*
  • Tomography, X-Ray Computed

Substances

  • Cytokines
  • Carbon Dioxide