Prognostic Value of Venous to Arterial Carbon Dioxide Difference during Early Resuscitation in Critically Ill Patients with Septic Shock

The partial pressure of venous to arterial carbon dioxide gradient (PCO gap) is considered as an alternative marker of tissue hypoperfusion and has been used to guide treatment for shock. The aim of this study was to investigate the prognostic value of venous-to-arterial carbon dioxide difference during early resuscitation of patients with septic shock and compared it with that of lactate clearance and Acute Physiology and Chronic Health Evaluation II (APACHE-II) score. Forty patients admitted to one Intensive Care Unit were enrolled. APACHE-II score was calculated on admission. An arterial blood gas, central venous, and lactate samples were obtained on admission and after 6 h, and lactate clearance was calculated. Patients were classified retrospectively into Group I (survivors) and Group II (nonsurvivors). Pv-aCO difference in the two groups was evaluated. Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. At T0, Group II showed high PCO gap (8.37 ± 1.36 mmHg) than Group I (7.55 ± 0.95 mmHg) with statistically significant difference ( = 0.030). While at T6, Group II showed higher PCO gap (9.48 ± 1.47 mmHg) with statistically significant difference ( < 0.001) and higher mean lactate values (62.71 ± 23.66 mg/dl) with statistically significant difference ( < 0.001) than Group I where PCO gap and mean lactate values became much lower, 5.91 ± 1.12 mmHg and 33.61 ± 5.80 mg mg/dl, respectively. Group I showed higher lactate clearance (25.42 ± 6.79%) with statistically significant difference ( < 0.001) than Group II (-69.40-15.46%). High PCO gap >7.8 mmHg after 6 h from resuscitation of septic shock patients is associated with high mortality.