Critical Care and Shock

Venous-arterial CO2 difference to arterial-venous O2 content difference ratio as marker of resuscitation in pediatric septic shock

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Objective: Sepsis is still a major cause of mortality in pediatric intensive care units. During initial resuscitation, central venous oxygen saturation (ScvO2) and/or lactate level have become a standard monitoring target nowadays. Carbon dioxide (CO2) partial pressure difference between central vein and artery (Pv-aCO2) has also been recommended as an additional marker to identify persistent global hypoperfusion. Recently, the Pv-aCO2/Ca-vO2 ratio, which represents respiratory quotient, is presumed to be superior in detecting anaerobic metabolism.

Design: Single center observational analytic research with cross-sectional study.

Setting: Resuscitation Room at academic hospital.

Patients and participants: Twenty-four pediatric patients with septic shock, aged 2 months to 12 years old.

Interventions: Patients were resuscitated at the Emergency Department of Dr. Soetomo General Academic Hospital, Surabaya. Initial first hour therapy included oxygenation, antibiotic administration, fluid bolus, and catecholamine titration. Central venous catheter was inserted in all patients through subclavian or jugular veins.

Measurements and results: Lactate was measured in the first and third hour after patient arrival. Arterial and central vein blood gas analysis was performed concurrently at the third hour. Patients were followed up after 48 hours to assess outcome. Pv-aCO2/Ca-vO2 ratio was more effective compared to ScvO2 and lactate clearance in predicting the 48-hour mortality rate (p 0.047). The cutoff value of the Pv-aCO2/Ca-vO2 ratio of 1.54 had the highest sensitivity and specificity to represent global hypoxia in pediatric patients with sepsis.

Conclusion: Pv-aCO2/Ca-vO2 ratio is a useful marker in predicting mortality in pediatric patients with septic shock.