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Venous-arterial PCO2 difference as an early predictor of organ dysfunction in the ICU


The early identification and scrupulous monitoring of tissue dysoxia can improve the management of critical patient. In this light, the final product of aerobe and anaerobe metabolism (that is, carbon dioxide) can provide useful information on adequacy of tissue perfusion and metabolism [1, 2]. The aim of our study was to evaluate whether the venous-arterial PCO2 gradient provides useful information on tissue dysfunction in patients admitted to the ICU.


We retrospectively studied 135 patients admitted to our ICU in 2006 with a length of stay >24 hours and a gas analysis from arterial and central venous blood at admission. Venous-arterial PCO2 gradient (ΔpCO2), organ dysfunction in the first 24 hours and ICU mortality were collected. Organ dysfunction was defined as a SOFA score ≥2 for each organ. The patients were subdivided and compared on the basis of ΔpCO2 value: ΔpCO2 ≥ 6 mmHg (High group) and ΔpCO2 <6 mmHg (Normal group).


Thirty-nine patients (29%) showed a ΔpCO2 ≥ 6 mmHg (ΔpCO2 9.6 ± 3.1). In the Normal group the mean ΔpCO2 value was 1.2 ± 4.1. The High group showed a larger rate (44%) of respiratory failure than the Normal group (25%) Similarly, cardiovascular dysfunction was observed in 49% of the patients of the High group and only in 19% of the Normal group (P < 0.05). Renal failure was also slightly larger in the High group (31%) than in the Normal group (22%) (P > 0.05). As expected, patients of the High group showed an ICU mortality (33%) three times larger (P < 0.05) than patients of the Normal group (12%).


The above data support the hypothesis that ΔpCO2 can provide useful information on the tissue perfusion and metabolism in ICU patients and can be used as a reliable biomarker for early prediction of organ dysfunction.


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Biagioni, E., Boni, E. & Girardis, M. Venous-arterial PCO2 difference as an early predictor of organ dysfunction in the ICU. Crit Care 14 (Suppl 1), P157 (2010).

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