Association between lactic acidosis and multiple organ dysfunction syndrome after cardiopulmonary bypass.

Background: The relationship between hyperlactatemia and prognosis after cardiopulmonary bypass (CPB) is controversial, and some studies ignore the presence of lactic acidosis in patients with severe hyperlactacemia. This study explored the association between lactic acidosis (LA) and the occurrence of multiple organ dysfunction syndrome (MODS) after cardiopulmonary bypass. Methods: This study was a post hoc analysis of patients who underwent cardiac surgery between February 2017 and August 2018 and participated in a prospective study at Taizhou Hospital. The data were collected at: ICU admission (H0), and 4, 8, 12, 24, and 48 h after admission. Blood lactate levels gradually increased after CPB, peaking at H8 and then gradually decreasing. The patients were grouped as LA, hyperlactatemia (HL), and normal control (NC) based on blood test results 8 h after ICU admission. Basic preoperative, perioperative, and postoperative conditions were compared between the three groups, as well as postoperative perfusion and oxygen metabolism indexes. Results: There were 22 (19%), 73 (64%), and 19 (17%) patients in the LA, HL, and NC groups, respectively. APACHE II (24h) and SOFA (24h) scores were the highest in the LA group (P < 0.05). ICU stay duration was the longest for the LA group (48.5 (42.5, 50) h), compared with the HL (27 (22, 48) h) and NC (27 (25, 46) h) groups (P = 0.012). The LA group had the highest incidence of MODS (36%), compared with the HL (14%) and NC (5%) groups (P = 0.015). In the LA group, the oxygen extraction ratio (O2ER) was lower (21.5 (17.05, 32.8)%) than in the HL (31.3 (24.8, 37.6)%) and the NC group (31.3 (29.0, 35.4) %) (P = 0.018). In the univariable analyses, patient age (OR = 1.054, 95% CI [1.003-1.109], P = 0.038), the LA group (vs. the NC group, (OR = 10.286, 95% CI [1.148-92.185], P = 0.037), and ΔPCO2 at H8 (OR = 1.197, 95% CI [1.022-1.401], P = 0.025) were risk factor of MODS after CPB. Conclusions: We speculated that there was correlation between lactic acidosis and MODS after CPB. In addition, LA should be monitored intensively after CPB.

ΔPCO2 and ΔPCO2/C(a-cv)O2 Are Not Predictive of Organ Dysfunction After Cardiopulmonary Bypass.

Background: Cardiac surgery is associated with a substantial risk of major adverse events. Although carbon dioxide (CO2)-derived variables such as venous-to-arterial CO2 difference (ΔPCO2), and PCO2 gap to arterial-venous O2 content difference ratio (ΔPCO2/C(a-cv)O2) have been successfully used to predict the prognosis of non-cardiac surgery, their prognostic value after cardiopulmonary bypass (CPB) remains controversial. This hospital-based study explored the relationship between ΔPCO2, ΔPCO2/C(a-cv)O2 and organ dysfunction after CPB. Methods: We prospectively enrolled 114 intensive care unit patients after elective cardiac surgery with CPB. Patients were divided into the organ dysfunction group (OI) and non-organ dysfunction group (n-OI) depending on whether organ dysfunction occurred or not at 48 h after CPB. ΔPCO2 was defined as the difference between central venous and arterial CO2 partial pressure. Results: The OI group has 37 (32.5%) patients, 27 of which (23.7%) had one organ dysfunction and 10 (8.8%) had two or more organ dysfunctions. No statistical significance was found (P = 0.84) for ΔPCO2 in the n-OI group at intensive care unit (ICU) admission (9.0, 7.0-11.0 mmHg), and at 4 (9.0, 7.0-11.0 mmHg), 8 (9.0, 7.0-11.0 mmHg), and 12 h post admission (9.0, 7.0-11.0 mmHg). In the OI group, ΔPCO2 also showed the same trend [ICU admission (9.0, 8.0-12.8 mmHg) and 4 (10.0, 7.0-11.0 mmHg), 8 (10.0, 8.5-12.5 mmHg), and 12 h post admission (9.0, 7.3-11.0 mmHg), P = 0.37]. No statistical difference was found for ΔPCO2/C(a-cv)O2 in the n-OI group (P = 0.46) and OI group (P = 0.39). No difference was detected in ΔPCO2, ΔPCO2/C(a-cv)O2 between groups during the first 12 h after admission (P > 0.05). Subgroup analysis of the patients with two or more failing organs compared to the n-OI group showed that the predictive performance of lactate and Base excess (BE) improved, but not of ΔPCO2 and ΔPCO2/C(a-cv)O2. Regression analysis showed that the BE at 8 h after admission (odds ratio = 1.37, 95%CI: 1.08-1.74, P = 0.009) was a risk factor for organ dysfunction 48 h after CBP. Conclusion : ΔPCO2 and ΔPCO2/C(a-cv)O2 cannot be used as reliable indicators to predict the occurrence of organ dysfunction at 48 h after CBP due to the pathophysiological process that occurs after CBP.