A comparison between measured and calculated central venous oxygen saturation in critically ill patients.

Background: Central venous oxygen saturation (ScvO2) is often used to help to guide resuscitation of critically ill patients. The standard gold technique for ScvO2 measurement is the co-oximetry (Co-oximetry_ScvO2), which is usually incorporated in most recent blood gas analyzers. However, in some hospitals, those machines are not available and only calculated ScvO2 (Calc_ScvO2) is provided.

Use of venous-to-arterial carbon dioxide tension difference to guide resuscitation therapy in septic shock.

The mixed venous-to-arterial carbon dioxide (CO2) tension difference [P (v-a) CO2] is the difference between carbon dioxide tension (PCO2) in mixed venous blood (sampled from a pulmonary artery catheter) and the PCO2 in arterial blood. P (v-a) CO2 depends on the cardiac output and the global CO2 production, and on the complex relationship between PCO2 and CO2 content. Experimental and clinical studies support the evidence that P (v-a) CO2 cannot serve as an indicator of tissue hypoxia, and should be regarded as an indicator of the adequacy of venous blood to wash out the total CO2 generated by the peripheral tissues.

Decrease in pulse pressure and stroke volume variations after mini-fluid challenge accurately predicts fluid responsiveness†.

Background: Dynamic indices, such as pulse pressure variation (PPV), are inaccurate predictors of fluid responsiveness in mechanically ventilated patients with low tidal volume. This study aimed to test whether changes in continuous cardiac index (CCI), PPV, and stroke volume variation (SVV) after a mini-fluid challenge (100 ml of fluid during 1 min) could predict fluid responsiveness in these patients.

Methods: We prospectively studied 49 critically ill, deeply sedated, and mechanically ventilated patients (tidal volume <8 ml kg(-1) of ideal body weight) without cardiac arrhythmias, in whom a fluid challenge was indicated because of circulatory failure.

Repeatability of blood gas parameters, PCO2 gap, and PCO2 gap to arterial-to-venous oxygen content difference in critically ill adult patients.

The objective of this study was to examine the repeatability of blood gas (BG) parameters and their derived variables such as the central venous-to-arterial carbon dioxide tension difference (▵PCO2) and the ratio of ▵PCO2 over the central arteriovenous oxygen content difference (▵PCO2/C(a-cv)O2) and to determine the smallest detectable changes in individual patients.A total of 192 patients with arterial and central venous catheters were included prospectively. Two subsequent arterial and central venous blood samples were collected immediately one after the other and analyzed using the same point-of-care BG analyzer.

Central venous-to-arterial carbon dioxide partial pressure difference in early resuscitation from septic shock: a prospective observational study.

Background: Central venous-to-arterial carbon dioxide partial pressure difference (ΔPCO2) can be used as a marker for the efficacy of venous blood in removing the total CO2 produced by the tissues. To date, this role of ΔPCO2 has been assessed only in patients after resuscitation from septic shock with already normalised central venous oxygen saturation (ScvO2 ≥70%). There are no reports on the behaviour of ΔPCO2 and its relationship to cardiac index (CI) and clinical outcome before normal ScvO2 has been achieved.

Mathematical coupling of data between global-end diastolic volume index and cardiac index calculated by the PiCCO device: myth or reality?

Background: Aim of the study was to investigate whether cardiac index (CI) and global end diastolic volume index (GEDVi) determined from the same thermodilution curve are mathematically coupled during the infusion of an inotropic agent in critically ill patients.

Methods: Seventeen patients were prospectively studied. CI and GEDVi were evaluated in triplicate by the transpulmonary thermodilution technique with the PiCCO system before and 20 to 30 minutes after increases in dobutamine infusion rate.

Time course of central venous-to-arterial carbon dioxide tension difference in septic shock patients receiving incremental doses of dobutamine.

Purpose: To assess the time course of the central venous-arterial carbon dioxide tension difference (∆PCO2)-as an index of the carbon dioxide production (VCO2)/cardiac index (CI) ratio-in stable septic shock patients receiving incremental doses of dobutamine.

Methods: Twenty-two hemodynamically stable septic shock patients with no signs of global tissue hypoxia, as testified by normal blood lactate levels, were prospectively included. A dobutamine infusion was administered at a dose of up to 15 μg/kg/min in increments of 5 μg/kg/min every 30 min.

Difference in venous-arterial carbon dioxide in septic shock.

Determining the venous-to-arterial PCO2 difference (PCO2gap) during resuscitation of septic shock patients might be useful when deciding when to continue resuscitation despite a ScvO2>70% associated with hyperlacticemia. Because hyperlacticemia is not a discriminatory factor in defining the cause of that stress, a PCO2gap>6 mmHg could be used to identify global tissue hypoperfusion. Monitoring the "Gap" could be a useful complementary tool after optimization of O2-derived parameters was achieved to evaluate the adequacy of blood flow to global metabolic demand.

The repeatability of Stewart's parameters and anion gap in a cohort of critically ill adult patients.

Purpose: To examine the repeatability of Stewart's parameters and anion gap in a cohort of critically ill patients and to determine the smallest detectable changes in individual patients.

Methods: A total of 161 patients were included prospectively. They underwent two subsequent blood samplings within 10 min of each other and samples were analyzed using the same central laboratory analyzer.