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Volume 2 Supplement 1


  • Oral presentation
  • Open Access

0032. Relationship between microcirculatory alterations and venous-to-arterial carbon dioxide differences in patients with septic shock

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Intensive Care Medicine Experimental20142 (Suppl 1) :O5

  • Published:


  • Septic Shock
  • Pulmonary Artery Catheter
  • Arterial Carbon Dioxide
  • Microvascular Perfusion
  • Microvascular Blood Flow


Increased venous to arterial carbon dioxide difference (Pv-aCO2) have been attributed to low cardiac output states. However, mechanisms conducting to Pv-aCO2 increases during normal or even high cardiac output conditions as in septic shock are not fully understood. We hypothesized that Pv-aCO2 could reflect the adequacy of microvascular perfusion during resuscitated septic shock


To test the hypothesis that Pv-aCO2 could reflect the microvascular blood flow during the early phases of resuscitation in septic shock


We included 80 patients with a first episode of septic shock admitted to a mixed ICU in a University Hospital over a 12-month period. Time 0 (T0) was set at ICU admission when a pulmonary artery catheter was inserted. Arterial and venous gases analyses were performed at T0 and 6 hours after (T6). We defined Pv-aCO2 as the difference between the mixed venous and arterial CO2 partial pressures. A Sidestream Dark-Field (SDF) imaging device (Microvision Medical, Amsterdam, the Netherlands) was used to evaluate the sublingual microcirculation both at T0 and T6. At each assessment, 5 sequences of 20 seconds each were recorded and stored under a random number. An investigator blinded to the sequence order and patient's clinical course, analyzed the sequences semi-quantitatively. The vessels were separated into large and small using a cut-off value of 20 µm in diameter. We evaluated the relation between the percentage of small vessels perfused and the Pv-aCO2 using linear and non-linear regressions and Spearman Rho test. A p< 0.05 was considered as significant.


We found significant but very weak relationships between general hemodynamics or oxygen derived parameters with Pv-CO2.Pv-aCO2 was inversely related to the percentage of small vessels perfused both at T0 and T6 (T0: R2:0.515, p< 0.001; T6: R2:0.453, p< 0.001).
Fig. 1
Fig. 1

Pv-aCO2 vs. SVP and CO at T0

Fig. 2
Fig. 2

Pv-aCO2 vs. SVP and CO at T6

Table 1

General hemodynamics and Oxygen-derived parameters




SvO2, (%)

68.8 (61.75-75.0)

69.7 (64.4-75.9)

Cardiac Index, (L/min/m2)

3.3 (2.4-4.0)

3.2 (2.7-3.8)

iDO2, (ml/min/m2)

389.0 (293.4-500.3)


iVO2, (ml/min/m2)

116.8 (87.3-150.4)

182.8 (106.3-240.4)

Pv-aCO2, (mmHg)

5.2 (3.6-7.2)

5.8 (3.5-7.7)


Microvascular blood flow is a key determinant of Pv-aCO2 during normodynamic septic shock. Pv-aCO2 could track microvascular alterations during early phases of septic shock.

Authors’ Affiliations

Fundación Valle del Lili, Universidad ICESI, Intensive Care Medicine Department, Cali, Colombia
Pontificia Universidad Católica de Chile, Facultad de Medicina, Departamento de Medicina Intensiva, Santiago, Chile
Free University of Brussels, Erasme Hospital, Intensive Care Medicine Department, Brussels, Belgium


© Ospina-Tascón et al; licensee Springer. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.