TO EVALUATE CENTRAL VENOUS TO ARTERIAL CO2 DIFFERENCE /ARTERIAL TO CENTRAL VENOUS O2 RATIO WITH LACTATE CLEARANCE IN PATIENTS WITH SEPTIC SHOCK

Aims and objectives

The present study is aimed to evaluate

1.The relationship between the P(cv-a)CO2/D(a-cv)O2 ratio and LC for 8 and 24 hours and

2. To define a cutoff value for the P(cv-a)CO2/D(a-cv)O2 ratio to identify an 8 and 24-hour LC at 10% and 20% respectively after resuscitation

Research question

Venous-to-arterial PCO2 /arterial-venous O2 content difference and to find a correlation of the above with lactate clearance in septic shock patients.

MATERIALS AND METHODS:

The global hemodynamic, arterial, and central venous blood gas analyses will be simultaneously performed on the T0, T8, T24 (in hours)

The position of the tip of the central venous catheter in the upper part of the right atrium will be confirmed on chest radiograph before sampling

Blood gas samples will be taken anaerobically in 3-mL heparinized syringes and analyzed for blood gas and the same blood gas machines will be used to analyze the arterial and central venous blood gas samples

The pairs of arterial and central venous blood samples were withdrawn simultaneously for determination of the following variables:

PaO2

PaCO2

Central venous oxygen tension (PcvO2)

Central venous carbon dioxide tension (PcvCO2) and SaO2

The Hb and lactate level will be measured from the arterial blood

The arterial oxygen content (CaO2), central venous oxygen content (CvO2), arterio venous oxygen content difference C(a-cv)O2,

veno arterial CO2 tension difference P(cv-a)CO2 ,

P(cv-a)CO2/C(a-cv)O2 ratio, lactate clearance rate (LC)

Lactate  clearance and survival will be defined as follows:

CaO2 = (1.34 × SaO2 × Hb) + (0.003 × PaO2)

CvO2 = (1.34 × SvO2 × Hb) + (0.003 × PvO2)

C(a-cv)O2 = CaO2  - CvO2

P(cv-a)CO2 = PvCO2 - PaCO2

P(cv-a)CO2/C(a-cv)O2 ratio = (PcvCO2-PaCO2)/(CaO2 - CvO2)

LC8 rate = (T0 lactate –T8 lactate)/(T0 lactate) × 100%

LC24 rate = (T0 lactate –T24 lactate)/(T0 lactate) × 100%

LC rate =10%from T0 toT8(hrs)

LCrate= 20%fromT0toT24(hrs)

Lactate clearance and survival will be defined as follows:

CaO2 = (1.34 × SaO2 × Hb) + (0.003 × PaO2)

CvO2 = (1.34 × SvO2 × Hb) + (0.003 × PvO2)

C(a-cv)O2 = CaO2 -CvO2

P(cv-a)CO2 = PvCO2 - PaCO2

P(cv-a)CO2/C(a-cv)O2 ratio = (PvCO2 -PaCO2)/(CaO2 -CvO2)

LC8 rate = (T0 lactate –T8 lactate)/(T0 lactate) × 100%

LC24 rate = (T0 lactate –T24 lactate)/(T0 lactate) × 100%

LC rate= 10%fromT0 toT8(hrs)

LCrate= 20%fromT0toT24(hrs)

4 groups

1.LC 8A (>10%)

2.LC 8B(<10%)

3.LC 24A(>20%)

4.LC 24B(<20%)