Modifications of tissular oxygenation and systemic hemodynamics after the correction of hypocapnia induced by mechanical ventilation

Rev Esp Fisiol. 1994 Mar;50(1):19-26.


The modifications of systemic hemodynamics, oxygen transport and tissular oxygenation in mechanically-ventilated critical ARF (acute respiratory failure) patients, after the correction of its hypocapnia by addition of dead space (VD) are determined. The prospective and randomized study was carried out in a multidisciplinary ICU. Fifteen ARF patients were studied within the first 48 hours of evolution. All the patients were intubated and mechanically ventilated. Three stages were delimited: I) 30 min after the beginning of anesthesia; II) 30 min after adding 30 cm of VD; III) 30 min after replacing the previous VD with a VD of 60 cm. Similar steady states had been reached when the measurements were taken. Ventilation parameters and FiO2 were kept stable. In stage I the patients presented a pure respiratory alkalosis and, with respect to hemodynamics, a hyperdynamic situation. In stage II the acid-base balance was normalized with a continuation of the hyperdynamic situation and an increase in mixed venous oxygen tension and saturation (PvO2 and SvO2) (p < 0.001). Stage III was characterized by a pure hypercapnic acidosis and an increase in capillary wedge pressure (CWP) (p < 0.05), right atrial pressure (RAP) (p < 0.001) and cardiac output (Qt) (p < 0.001); simultaneously, the systemic vascular resistances (SVR) decreased (p < 0.01), the PvO2, SvO2 and oxygen delivery (DO2) increased (p < 0.001); oxygen utilization coefficient (OUC) decreased (p < 0.01). The results suggest that the variations in PvO2 and SvO2 are a direct consequence of the modifications in blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Acute Disease
  • Adult
  • Aged
  • Female
  • Hemodynamics*
  • Humans
  • Hypocapnia / etiology
  • Hypocapnia / therapy*
  • Male
  • Middle Aged
  • Oxygen / blood
  • Oxygen Consumption*
  • Partial Pressure
  • Prospective Studies
  • Respiration, Artificial / adverse effects*
  • Respiratory Dead Space
  • Respiratory Insufficiency / blood
  • Respiratory Insufficiency / therapy
  • Vascular Resistance


  • Oxygen