High veno-arterial carbon dioxide gradient is not predictive of worst outcome after an elective cardiac surgery: a retrospective cohort study

Morel, J.; Grand, Nathalie; Axiotis, Grégory; Bouchet, J. B.; Faure, Michael; Auboyer, C.; Vola, Marco; Molliex, Serge

doi:10.1007/s10877-016-9855-3

Cited by 25 publications

(23 citation statements)

References 24 publications

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“…Although many studies confirmed the association between an elevation in both ∆PCO 2 and ∆PCO 2 /C a-v O 2 ratio and poor outcome in terms of lactate clearance, changes in VO 2 and mortality (40)(41)(42), some other ones showed a limited or even a negative correlation between elevated ∆PCO 2 and increase in blood lactate or mortality (43)(44)(45). Part of the discrepancy might be related to the fact that the latter studies were performed in post-cardiac surgery patients.…”

Section: Errors and Pitfalls Of The Pco 2 Gapmentioning

confidence: 99%

How can CO2-derived indices guide resuscitation in critically ill patients?

Gavelli¹,

Teboul²,

Monnet³

2019

J. Thorac. Dis

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Assessing the adequacy of oxygen delivery with oxygen requirements is one of the key-goal of haemodynamic resuscitation. Clinical examination, lactate and central or mixed venous oxygen saturation (S v O 2 and S cv O 2 , respectively) all have their limitations. Many of them may be overcome by the use of the carbon dioxide (CO 2)-derived variables. The venoarterial difference in CO 2 tension ("ΔPCO 2 " or "PCO 2 gap") is not an indicator of anaerobic metabolism since it is influenced by the oxygen consumption. By contrast, it reliably indicates whether blood flow is sufficient to carry CO 2 from the peripheral tissue to the lungs in view of its clearance: it, thus, reflects the adequacy of cardiac output with the metabolic condition. The ratio of the PCO 2 gap with the arteriovenous difference of oxygen content (PCO 2 gap/C a-v O 2) might be a marker of anaerobiosis. Conversely to S v O 2 and S cv O 2 , it remains interpretable if the oxygen extraction is impaired as it is in case of sepsis. Compared to lactate, it has the main advantage to change without delay and to provide a real-time monitoring of tissue hypoxia.

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Section: Errors and Pitfalls Of The Pco 2 Gapmentioning

confidence: 99%

How can CO2-derived indices guide resuscitation in critically ill patients?

Gavelli¹,

Teboul²,

Monnet³

2019

J. Thorac. Dis

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“…Our findings agree with other studies that showed a weak correlation between Pv-aCO2 difference with some physiologic parameters like CI, pH, Hb, BE, SvO2, etc. (29,30). Moreover, it has been shown that this variable was not able to detect significant changes in systemic blood flow, and global O2 derived metabolism following goal-directed therapy, (1) or after fluid challenges in cardiac surgery patients.…”

Section: Discussionmentioning

confidence: 99%

Role of Pv-aCO2 gradient and Pv-aCO2/Ca-vO2 ratio during Cardiac Surgery

Bouchacourt

Hurtado

Kohn

et al. 2020

Preprint

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Background. Arterial lactate, mixed venous O2 saturation and parameters derived from CO2 metabolism as the venous minus arterial CO2 partial pressure (Pv-aCO2) gradient and the ratio between this gradient and the arterial minus venous oxygen content (Pv-aCO2/Ca-vO2) were proposed as markers of tissue hypoperfusion and oxygenation. The main goals were to characterize their physiologic determinants of Pv-aCO2 difference, and the Pv-aCO2 /Ca-vO2 ratio and the interchangeability of the variables calculated from mixed and central venous samples. Methods. We made a sub-analysis of 35 cardiac surgery patients included in a previous investigation database. Parameters were measured or calculated: after anesthesia induction (T1), end of cardiac surgery (T2), and at 6-8 hours intervals after ICU admission (T3 and T4). Results. Macrohemodynamics was characterized by increased cardiac index and low systemic vascular resistances, after surgery (p<0.05). Hemoglobin, arterial pH, lactate, and systemic O2 metabolism showed significant but transient changes during the study (p<0.05). Pv-aCO2 remained high and without changes along the study, and Pv-aCO2/Ca-vO2 was also high and only decreased at T4 (p<0.05). A weak but significant correlation was observed both, globally and at each time interval, between Pv-aCO2 or Pv-aCO2/Ca-vO2 with factors that may affect the CO2 hemoglobin dissociation. Using a similar approach, a multilevel linear regression model with Pv-aCO2 and Pv-aCO2/Ca-vO2 as outcome variables showed a significant association for Pv-aCO2 with mixed venous O2 saturation (SvO2), and base excess (BE) (p<0.05), while Pv-aCO2/Ca-vO2 was significantly associated with Hb, SvO2 , and BE (p<0.05) but not with cardiac output. Measurements and calculations from mixed and central venous blood were not interchangeable. Conclusions. Since Pv-aCO2 and Pv-aCO2/Ca-vO2 could be influenced by different factors that affect the CO2 dissociation curve, these variables should be considered with caution during the hemodynamic management of cardiac surgery patients. Finally, central venous and mixed values were not interchangeable.

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“…For example, in the Robin's study, this gradient was significantly different between complicated and non-complicated patients at admission in intensive care unit, but tended to subsequently decrease. In the Morel's [4] study, the number of patients having a high gradient was greater at 6th postoperative hour. It is likely that the circulatory management brought into play to the high risk patients may rapidly modify the gradient whereas the tissue insult induced by the microvascular disorder is still an ongoing process.…”

mentioning

confidence: 88%

“…In this issue Morel et al [4] retrospectively analysed 220 consecutive patients admitted in intensive care unit after an elective cardiac surgery. Monitoring p(mv-a)CO 2 , they observed at the 6th postoperative hour a group of 55 patients having a gradient greater than 6 mm Hg.…”

mentioning

confidence: 99%

The venous–arterial partial pressure of carbon dioxide as a new monitoring of circulatory disorder: no so simple

Viale

2016

J Clin Monit Comput

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Restoring or maintaining an optimal oxygen supply adjusted to oxygen demand remains the key aim of all clinicians facing a circulatory dysfunction, whatever the cause. Many therapeutic tools are available, ranging from adequate fluid resuscitation, cardio or vaso-active agents, to adjuvant therapies and various ventilatory supports. Most of the challenges for clinicians are the choice of therapeutics, their dosage, and management of their potential interactions. In addition, in the course of circulatory distress, it would be of great help to identify patients at risk of developing organ dysfunction, in order to intensify and adapt treatment of such individuals. As a guide to achieve these purposes, normalisation of mixed venous oxygen saturation and blood lactate has been proposed as endpoint resuscitations but revealed unsuccessful in several clinical studies [1][2][3]. The monitoring of the mixed venous-arterial gradient in partial pressure of carbon dioxide [p(mv-a)CO 2 ] has been recently put forward and revealed promising. A high CO 2 gradient would indicate an inadequate organ perfusion and a risk of delayed organ dysfunction. Have we reached a satisfactory answer to a main clinical question?In this issue Morel et al.[4] retrospectively analysed 220 consecutive patients admitted in intensive care unit after an elective cardiac surgery. Monitoring p(mv-a)CO 2 , they observed at the 6th postoperative hour a group of 55 patients having a gradient greater than 6 mm Hg. Surprisingly and contrary to previous published results, these patients experienced a lower SOFA score, hospital and 6 month mortality. The authors concluded that in this clinical setting, the CO 2 gradient is not predictive of poor outcome. This apparently paradoxical results is on line with other works underlying the poor discriminative value of the gradient [5]. Rather than the premature conclusion of a promising story, this is more likely a plea to gain more insight in our knowledge about a complex indicator.The p(mv-a)CO 2 is the difference between two partial pressures of CO 2 : the mixed venous and the arterial. The normal value is commonly held as lower than 6 mm Hg. The venous pressure depends on several components, the content of mixed venous in CO 2 , and the relationship between the concentration and the pressure. The content itself is a concentration, that is to say the ratio of the amount of CO 2 driven from peripheral organs to the amount of blood arising from the same organs or segments of organs. The arterial pressure depends on the lung function and is strictly proportional to the alveolar ventilation. Given a constant alveolar ventilation, this arterial pressure remains stable provided that the venous pressure is not modified. If an increase in mixed venous pCO 2 occurs, the amount of CO 2 exhaled by the lung will increase, enlarging the venous-arterial gradient. This role of the lung is schematically illustrated by the increase in end-tidal partial pressure of CO 2 occurring soon after the release of a tourniquet. Any small i...

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High veno-arterial carbon dioxide gradient is not predictive of worst outcome after an elective cardiac surgery: a retrospective cohort study

Cited by 25 publications

References 24 publications

How can CO2-derived indices guide resuscitation in critically ill patients?

How can CO2-derived indices guide resuscitation in critically ill patients?

Role of Pv-aCO2 gradient and Pv-aCO2/Ca-vO2 ratio during Cardiac Surgery

The venous–arterial partial pressure of carbon dioxide as a new monitoring of circulatory disorder: no so simple

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