Lee YJ, et al. Ann Surg Treat Res. 2021 Jan;100(1):47-53. https://doi.org/10.4174/astr.2021.100.1.47

Blood gas analysis is an essential diagnostic tool used for assessing acid-base balance, ventilation, and oxygenation in critically ill patients. Arterial blood gas analysis (ABGA) remains the gold standard, primarily due to its accuracy in measuring oxygenation. Venous blood gas analysis (VBGA), in contrast, serves as a less invasive alternative and is particularly useful for evaluating acid-base status and metabolic function. Important parameters such as oxygen saturation of central venous blood (ScvO₂) and venous-to-arterial carbon dioxide pressure difference (∆pv-aCO₂) provide critical insights into hemodynamic status, cardiac output, and tissue perfusion. Although VBGA cannot replace ABGA for the precise assessment of oxygenation, it remains a valuable tool in clinical scenarios involving hemodynamic monitoring, shock management, and critical care decision-making.

Purpose: Change in venous-to-arterial carbon dioxide partial pressure difference[P(v-a)CO₂] could be a useful marker to assess tissue perfusion status. Herein, we assessed the predictive values of postoperative P(v-a)CO₂ measurements for mortality in critically ill patients after major surgery. The correlation between P(v-a)CO₂ values and other conventional parameters of patient prognosis was also evaluated. Methods: Patients admitted to the intensive care unit(ICU) after abdominal surgery were enrolled. Arterial and venous blood gas analyses were performed within 1 h(T0) and after 24 h(T1) of admission to the ICU, respectively. The relationship between P(v-a)CO ₂ levels at T1 and other conventional parameters were assessed using a Bland-Altman plot. Logistic regression analysis was performed to examine the predisposing factors of mortality after surgery. Results: A total of 231 patients were finally analyzed. We divided the participants into the high PvaCO₂ group[P(v-a)CO₂ ≥ 8.6] and the low PvaCO₂ group[P(v-a)CO₂ < 8.6]. Seven-day-, 28-day, and in-hospital mortality were significantly higher in the high PvaCO₂ group than in the low PvaCO₂ group. There was significant agreement between P(v-a)CO₂ values at T1 and APACHE II scores, lactate levels at T1 and total SOFA scores at T1. In multivariate logistic analysis, an increased P(v-a)CO₂ value at T1 was the only significant risk factor of 7-day mortality after surgery. [odds ratio:1.341, 95%confidence interval: 1.050–1.714, p=0.019]. Conclusion: P(v-a)CO₂ measurements could be not only a significant predictor of postoperative prognosis, but also a useful surveillance parameter to maintain tissue perfusion after abdominal surgery in patients with a potential risk of fatal complication-related tissue hypoperfusion.

Background/Objectives: Endotoxin, a component of lipopolysaccharide (LPS) from bacteria, disrupts the immune system, potentially leading to multiorgan failure. Unlike previous studies, we enrolled patients with mild clinical conditions after major abdominal surgery and assessed the predictive value of endotoxin activity (EA) levels for acute complications which occur within 7 days postoperatively. Also, the differential diagnostic value of EA was assessed in a subgroup of patients with abnormal liver function during the immediate postoperative period. Methods: Patients admitted to the surgical ICU of our institution following elective abdominal surgery were enrolled. Participants were classified into low/high postoperative EA groups based on EA cutoff values for predicting complications. Additionally, participants were categorized based on liver function assessed at ICU admission using total bilirubin (TB) levels. Abnormal liver function was defined as a TB level > 1.2 mg/dL. Results: 86 patients were analyzed. The EA cutoff for postoperative complications was 0.485, with 49 patients (57%) categorized in the low EA group (EA levels < 0.485) and 37 patients (43%) in the high EA group (EA levels ≥ 0.485). The high EA group experienced statistically worse outcomes, including longer ICU stays and higher mortality rates. Logistic regression analysis confirmed that EA levels and SOFA scores were significant predictors of postoperative complications. For patients with elevated TB, the EA cutoff value for postoperative complications was 0.515, which is higher than those obtained for the total patient cohort. Conclusions: EA level is a viable surveillance tool for detecting postoperative complications in the acute period among ICU patients undergoing major abdominal surgery, and must be interpreted carefully considering the patient’s liver function.

Purpose: The venous-to-arterial carbon dioxide partial pressure difference [P(v-a)CO₂] reflects the adequacy of tissue perfusion, with elevated values suggesting impaired clearance of CO₂. While its prognostic role has been investigated in septic shock and high-risk surgery, evidence in postoperative critically ill patients remains limited. This study aimed to evaluate the prognostic value of ΔP(v-a)CO₂ after major abdominal surgery and its relationship with microcirculatory markers. Methods: We retrospectively analyzed 86 patients admitted to the intensive care unit (ICU) after major abdominal surgery between September 2020 and October 2023. Arterial and central venous blood gas analyses were performed immediately postoperatively and at 24 h. Patients were stratified into groups according to ΔP(v-a)CO₂ (≤ 0 vs. >0). Postoperative outcomes and correlations with central venous oxygen saturation (ScvO₂) were assessed. Results: In the subgroup analysis of patients with an initial P(v-a)CO₂ > 6 mmHg, those in the ΔP(v-a)CO₂ > 0 group required mechanical ventilation (54.5% vs. 22.2%, p = 0.033) and continuous renal replacement therapy (36.4% vs. 8.9%, p = 0.020) more frequently, with longer durations of both interventions (p = 0.011 and p = 0.016, respectively). ICU length of stay and the incidence of acute kidney injury were significantly lower in the ΔP(v-a)CO₂ ≤ 0 group. In addition, a modest negative correlation was observed between ScvO₂ measured at 24 h postoperatively and ΔP(v-a)CO₂. Conclusions: ΔP(v-a)CO₂ may serve as a useful marker for postoperative risk stratification in critically ill patients undergoing major abdominal surgery. However, given the retrospective design, small sample size, and single-center setting, these findings should be considered hypothesis-generating and require confirmation in larger, prospective multicenter studies.