Related Experiment Video
Updated: Aug 20, 2026

Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
Intramucosal-arterial Pco2 gradient does not reflect intestinal dysoxia in anemic hypoxia
Arnaldo Dubin1, Elisa Estenssoro, Gastón Murias
1Cátedra de Farmacología, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina. arnaldodubin@speedy.com.ar
Background:
An increase in intramucosal-arterial Pco2 gradient (DeltaPco2) might be caused by tissue hypoxia or by diminished blood flow. Our hypothesis was that DeltaPco2 should not be altered in anemic hypoxia with preserved blood flow.
Methods:
In 18 anesthetized, mechanically ventilated sheep, oxygen transport was stepwise reduced by hemorrhage (hypovolemia, n = 9) or by hemorrhage and simultaneous dextran infusion (hemodilution, n = 9).
Results:
Hypovolemia and hemodilution produced comparable decreases in systemic and intestinal oxygen transport and uptake. However, mixed venoarterial and mesenteric venoarterial Pco2 gradients and DeltaPco2 were significantly higher in hypovolemia than in hemodilution (25 +/- 5 vs. 10 +/- 2 mm Hg; 21 +/- 6 vs. 10 +/- 5 mm Hg; and 41 +/- 18 vs. 14 +/- 9 mm Hg, respectively; p < 0.01).
Conclusion:
DeltaPco2 did not reflect intestinal dysoxia during Vo2/Do2 dependency attributable to hemodilution. Blood flow seems to be the main determinant of DeltaPco2.
Related Concept Videos
Diagnosing Acidosis and Alkalosis
First, the pH level is assessed to determine whether the blood pH is normal (7.35–7.45), low (acidosis), or high (alkalosis).
Next, the PCO2 and HCO3− values are examined to...
Oxygen Transport in the Blood
Assessment of Diffusion and Perfusion
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
Carbon Dioxide Transport in the Blood
Forms of CO2 Transport
1. Dissolved in plasma: A small percentage (7-10%) of CO2 is transported and dissolved directly in the plasma.
2. Carbaminohemoglobin: Just over 20% of CO2 is chemically bound to...
Chemical Factors Affecting Respiration Centers
CO2 has a potent influence on respiration and is strictly regulated. Under...
Acute Respiratory Failure-II
The underlying physiological abnormalities that contribute to hypoxemic respiratory failure include:

