Acute hyperventilation increases the central venous-to-arterial PCO2 difference in stable septic shock patientsReport as inadecuate

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Annals of Intensive Care

, 7:31

First Online: 20 March 2017Received: 22 November 2016Accepted: 11 March 2017DOI: 10.1186-s13613-017-0258-5

Cite this article as: Mallat, J., Mohammad, U., Lemyze, M. et al. Ann. Intensive Care 2017 7: 31. doi:10.1186-s13613-017-0258-5


BackgroundTo evaluate the effects of acute hyperventilation on the central venous-to-arterial carbon dioxide tension difference ∆PCO2 in hemodynamically stable septic shock patients.

MethodsEighteen mechanically ventilated septic shock patients were prospectively included in the study. We measured cardiac index CI, ∆PCO2, oxygen consumption VO2, central venous oxygen saturation ScvO2, and blood gas parameters, before and 30 min after an increase in alveolar ventilation increased respiratory rate by 10 breaths-min.

ResultsArterial pH increased significantly from 7.35 ± 0.07 to 7.42 ± 0.09, p < 0.001 and arterial carbon dioxide tension decreased significantly from 44.5 41–48 to 34 30–38 mmHg, p < 0.001 when respiratory rate was increased. A statistically significant increase in VO2 from 93 76–105 to 112 95–134 mL-min-m, p = 0.002 was observed in parallel with the increase in alveolar ventilation. While CI remained unchanged, acute hyperventilation led to a significant increase in ∆PCO2 from 4.7 ± 1.0 to 7.0 ± 2.6 mmHg, p < 0.001 and a significant decrease in ScvO2 from 73 ± 6 to 67 ± 8%, p < 0.001. A good correlation was found between changes in arterial pH and changes in VO2 r = 0.67, p = 0.002. Interestingly, we found a strong association between the increase in VO2 and the increase in ∆PCO2 r = 0.70, p = 0.001.

ConclusionsAcute hyperventilation provoked a significant increase in ∆PCO2, which was the result of a significant increase in VO2 induced by hyperventilation. The clinician should be aware of the effects of acute elevation of alveolar ventilation on ∆PCO2.

KeywordsAcute hyperventilation Oxygen consumption Central venous-to-arterial CO2 tension gap Central venous oxygen saturation Septic shock AbbreviationsCIcardiac index

DO2oxygen delivery

VO2oxygen consumption

ScvO2central venous oxygen saturation

∆PCO2central venous-to-arterial carbon dioxide tension difference

CaO2oxygen content

CcvO2central venous oxygen content

PaCO2arterial carbon dioxide tension

PcvCO2central venous carbon dioxide tension

SaO2arterial oxygen saturation

HRheart rate

MAPmean arterial pressure


ICUintensive care unit

PEEPend-expiratory pressure

OEoxygen extraction

Electronic supplementary materialThe online version of this article doi:10.1186-s13613-017-0258-5 contains supplementary material, which is available to authorized users.

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Author: Jihad Mallat - Usman Mohammad - Malcolm Lemyze - Mehdi Meddour - Marie Jonard - Florent Pepy - Gaelle Gasan - Stephanie Ba



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