Carbon Dioxide Partial Pressure Difference Research Articles

CENTRAL VENOUS-TO-ARTERIAL CARBON DIOXIDE PARTIAL PRESSURE DIFFERENCE AS A GUIDING PARAMETER FOR CARDIOTONIC DRUG ADMINISTRATION IN PATIENTS WITH EARLY-STAGE SEPTIC SHOCK.

Objective: This study aimed to investigate the effect of the central venous-to-arterial carbon dioxide partial pressure difference (Pcv-aCO2) on the administration of cardiotonic drugs in patients with early-stage septic shock. Methods: A retrospective study was conducted on 120 patients suffering from septic shock. At admission, the left ventricular ejection fraction (LVEF) and Pcv-aCO2 of the patients were obtained. On the premise of mean arterial pressure ≥ 65 mm Hg, the patients were divided into two groups according to the treatment approaches adopted by different doctors-control group: LVEF ≤50% and observation group: Pcv-aCO2 ≥ 6. Both groups received cardiotonic therapy. Results: The two groups of patients had similar general conditions and preresuscitation conditions ( P > 0.05). Compared with the control group, the observation group had a higher mean arterial pressure, lactic acid clearance rate, and urine output after 6 h of resuscitation ( P < 0.05), but a lower absolute value of lactic acid, total fluid intake in 24 h, and a lower number of patients receiving renal replacement therapy during hospitalization ( P < 0.05). After 6 hours of resuscitation, the percentages of patients meeting central venous oxygen saturation and central venous pressure targets were not significantly different between the control and observation groups ( P > 0.05). There was no difference in the 28-day mortality rate between the two groups ( P > 0.05). Conclusion: Pcv-aCO2 is more effective than LVEF in guiding the administration of cardiotonic drugs in the treatment of patients with septic shock.

Research progress of diagnostic and therapeutic value of carbon dioxide-derived indicators in patients with sepsis

Effectively assessing oxygen delivery and demand is one of the key targets for fluid resuscitation in sepsis. Clinical signs and symptoms, blood lactic acid levels, and mixed venous oxygen saturation (SvO2) or central venous oxygen saturation (ScvO2) all have their limitations. In recent years, these limitations have been overcome through the use of derived indicators from carbon dioxide (CO2) such as mixed veno-arterial carbon dioxide partial pressure difference (Pv-aCO2, PCO2 gap, or ΔPCO2), the ratio of mixed veno-arterial carbon dioxide partial pressure difference to arterial-mixed venous oxygen content difference (Pv-aCO2/Ca-vO2). Pv-aCO2, PCO2 gap or ΔPCO2 is not a purely anaerobic metabolism indicator as it is influenced by oxygen consumption. However, it reliably indicates whether blood flow is sufficient to carry CO2 from peripheral tissues to the lungs for clearance, thus reflecting the adequacy of cardiac output and metabolism. The Pv-aCO2/Ca-vO2 may serve as a marker of hypoxia. SvO2 and ScvO2 represent venous oxygen saturation, reflecting tissue oxygen utilization. When oxygen delivery decreases but tissues still require more oxygen, oxygen extraction rate usually increases to meet tissue demands, resulting in decreased SvO2 and ScvO2. But in some cases, even if the oxygen delivery rate and tissue utilization rate of oxygen are reduced, it may still lead to a decrease in SvO2 and ScvO2. Sepsis is a classic example where tissue oxygen utilization decreases due to factors such as microcirculatory dysfunction, even when oxygen delivery is sufficient, leading to decrease in SvO2 and ScvO2. Additionally, the solubility of CO2 in plasma is approximately 20 times that of oxygen. Therefore, during sepsis or septic shock, derived variables of CO2 may serve as sensitive markers for monitoring tissue perfusion and microcirculatory hemodynamics. Its main advantage over blood lactic acid is its ability to rapidly change and provide real-time monitoring of tissue hypoxia. This review aims to demonstrate the principles of CO2-derived variables in sepsis, assess the available techniques for evaluating CO2-derived variables during the sepsis process, and discuss their clinical relevance.

A Multi-Center Randomized Controlled Study Using ΔPCO2/Ca-vO2 as the Target to Guide Early Tissue Hypoperfusion in Sepsis in Plateau Areas

Objective: To explore the value of using the venous-arterial carbon dioxide partial pressure difference and the arterial-venous oxygen content difference ratio (ΔPCO2/Ca-vO2) as targets to guide early tissue hypoperfusion in sepsis in plateau areas. Methods: 90 sepsis patients admitted to the Third People’s Hospital of Xining and Golmud People’s Hospital from June 2017 to December 2022 were selected as the research subjects, and they were divided into the ScvO2 (central venous oxygen saturation) group and the ΔPCO2/Ca-vO2 group, with 45 cases in each group. The two groups were treated with early shock resuscitation according to different protocols. The hemodynamic characteristics of the two groups of patients before and after resuscitation were observed, and the volume responsiveness was evaluated. The ROC (receiver operating characteristic) curve was used to analyze the significance of ΔPCO2/Ca-vO2, ScvO2, lactate, lactate clearance, and urine output in evaluating patient prognosis and the correlation between ΔPCO2/Ca-vO2 and the above indicators was explored. Results: Compared with before resuscitation, after fluid resuscitation, the heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), cardiac index (CI), lactate, lactate clearance rate, and urine output of the two groups of patients were significantly improved (P &lt; 0.05); in terms of therapeutic effect, the 28-day mortality rate, 6-hour fluid balance, and lactic acid clearance of the ΔPCO2/Ca-vO2 group were better than the ScvO2 group. The ROC characteristic curve showed that the ΔPCO2/Ca-vO2 value can effectively predict the prognosis of patients (AUC = 0.907, sensitivity was 97%, specificity was 72.4%, and critical value was 1.84). ΔPCO2/Ca-vO2 significantly correlated with ScvO2, lactic acid, and lactic acid clearance rate. Conclusion: The ΔPCO2/Ca-vO2 value can be used to guide fluid resuscitation in early hypoperfusion in sepsis in plateau areas, improve patients’ hemodynamics, reduce lactate indicators, and increase urine output. ΔPCO2/Ca-vO2 level &gt; 1.84 can effectively improve patient prognosis.&#x0D; Corrigendum available at: https://www.doi.org/10.26689/jcnr.v8i2.6467

Venous-to-arterial carbon-dioxide tension difference as a useful predictor of patient prognosis after major surgery

PurposeChange 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. MethodsPatients 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)CO2 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. ResultsA 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]. ConclusionP(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.

Correlation of venous to arterial carbon dioxide partial pressure difference with other cardiac output indices in patients undergoing intracardiac repair for tetralogy of fallot.

Clearance of tissue carbon dioxide by circulation is measured by venous to arterial carbon dioxide partial pressure difference (AVCO2) and is correlated with cardiac output (CO) in critically ill adult patients. This study aimed to correlate AVCO2 with other CO indices like arteriovenous oxygen saturation difference (AVO2), central venous oxygen saturation (ScVO2), and serum lactate in pediatric patients undergoing intracardiac repair (ICR) for tetralogy of Fallot (TOF). We conducted a prospective observational study in 50 patients, of age 5 months to 5 years, undergoing ICR for TOF and analyzed AVO2, AVCO2, ScVO2, and lactate from arterial and venous blood gas pairs obtained at different time intervals from admission to pediatric intensive care unit (PICU) (T0), at 6 h (T1), 12 h (T2), 24 h (T3), and 48 h (T4) postoperatively. Bivariate correlations were analyzed using Pearson for parametric variables. Admission AVCO2 was not correlated with AVO2 (R2 = 0.166, P = 0.246), ScVO2 (R2 = -2.2, P = 0.124), and lactate (R2 = -0.07, P = 0.624). At T1, AVCO2 was correlated with AVO2 (R2 = 0.283, P = 0.0464) but not with ScVO2 (R2 = - 0.25, P = 0.079) and lactate (R2 = -0.07, P = 0.623). At T2, T3 and T4, AVCO2 was correlated with AVO2 (R2 = 0.338,0.440 & 0.318, P = 0.0162, 0.0013, and 0.024), ScVO2 (R2 = - 0.344, - 0.488, and -0.366; P = 0.0143, <0.0001, and 0.017), and lactate (R2 = 0.305, 0.467 and 0.607; P = 0.0314, 0.00062 and <0.0001). AVCO2 was negatively correlated with ScVO2. No correlation observed between admission AVCO2 and mechanical ventilation duration. Two nonsurvivors had higher value of admission AVCO2 compared to survivors. AVCO2 is correlated with other CO surrogates like AVO2, ScVO2, and lactate in pediatric patients undergoing ICR for TOF.

Predictive value of Pv-aCO2/Ca-vO2 combined blood lactate concentration for primary peritonitis-related septic shock in children

To investigate the prognostic value of the ratio of veno-arterial carbon dioxide partial pressure difference to arterio-venous oxygen content difference (Pv-aCO2/Ca-vO2) in children with primary peritonitis-related septic shock. A retrospective study was conducted. Sixty-three children with primary peritonitis-related septic shock admitted to department of intensive care unit of the Children's Hospital Affiliated to Xi'an Jiaotong University from December 2016 to December 2021 were enrolled. The 28-day all-cause mortality was the primary endpoint event. The children were divided into survival group and death group according to the prognosis. The baseline data, blood gas analysis, blood routine, coagulation, inflammatory status, critical score and other related clinical data of the two groups were statistics. The factors affecting the prognosis were analyzed by binary Logistic regression, and the predictability of risk factors were tested by the receiver operator characteristic curve (ROC curve). The risk factors were stratified according to the cut-off, Kaplan-Meier survival curve analysis compared the prognostic differences between the groups. A total of 63 children were enrolled, including 30 males and 33 females, the average age (5.6±4.0) years old, 16 cases died in 28 days, with mortality was 25.4%. There were no significant differences in gender, age, body weight and pathogen distribution between the two groups. The proportion of mechanical ventilation, surgical intervention, vasoactive drug application, and procalcitonin, C-reactive protein, activated partial thromboplastin time, serum lactate (Lac), Pv-aCO2/Ca-vO2, pediatric sequential organ failure assessment, pediatric risk of mortality III in the death group were higher than those in the survival group. Platelet count, fibrinogen, mean arterial pressure were lower than those in the survival group, and the differences were statistically significant. Binary Logistic regression analysis showed that Lac and Pv-aCO2/Ca-vO2 were independent risk factors affecting the prognosis of children [odds ratio (OR) and 95% confidence interval (95%CI) were 2.01 (1.15-3.21), 2.37 (1.41-3.22), respectively, both P < 0.01]. ROC curve analysis showed that the area under curve (AUC) of Lac, Pv-aCO2/Ca-vO2 and their combination were 0.745, 0.876 and 0.923, the sensitivity were 75%, 85% and 88%, and the specificity were 71%, 87% and 91%, respectively. Risk factors were stratified according to cut-off, and Kaplan-Meier survival curve analysis showed that the 28-day cumulative probability of survival of Lac ≥ 4 mmol/L group was lower than that in Lac < 4 mmol/L group [64.29% (18/28) vs. 82.86% (29/35), P < 0.05]. Pv-aCO2/Ca-vO2 ≥ 1.6 group 28-day cumulative probability of survival was less than Pv-aCO2/Ca-vO2 < 1.6 group [62.07% (18/29) vs. 85.29% (29/34), P < 0.01]. After a hierarchical combination of the two sets of indicator variables, the 28-day cumulative probability of survival of Pv-aCO2/Ca-vO2 ≥ 1.6 and Lac ≥ 4 mmol/L group significantly lower than that of the other three groups (Log-rank test, χ2 = 7.910, P = 0.017). Pv-aCO2/Ca-vO2 combined with Lac has a good predictive value for the prognosis of children with peritonitis-related septic shock.

Relationship between Dynamic Changes of Microcirculation Flow, Tissue Perfusion Parameters, and Lactate Level and Mortality of Septic Shock in ICU.

Background Septic shock is a common clinical critical disease with high mortality, hemodynamic instability, and easy to be complicated with multiple organ failure. The rapid progress of the patient's condition poses a serious threat to patient's safety. Aim To investigate the relationship between the dynamic monitoring of microcirculation perfusion parameters and blood lactic acid level and the prognosis of patients with infection shock in ICU. Methods A total of 104 patients with septic shock admitted to ICU of Affiliated Hai'an Hospital of Nantong University from February 2018 to June 2021 were selected for clinical research. According to the survival situation of patients after 28 days of treatment, they were divided into the death group (n = 48) and the survival group (n = 56). The central venous-arterial carbon dioxide partial pressure difference (Pcv-aCO2), the ratio of central venous-arterial carbon dioxide partial pressure difference to arterial central venous oxygen content difference (Pcv-aCO2/Ca-cvO2), and blood lactic acid level were retrospectively analyzed and compared between the two groups on the first, third, and seventh days after admission to ICU. The odds ratio (OR) of three indexes affecting the prognosis of patients with septic shock was analyzed by univariate and multivariate mathematical models, and the value of three indexes in predicting the prognosis of patients was analyzed by receiver operating curve (ROC). Results Pcv-aCO2 and lactic acid in the death group were higher than those in the survival group on the 1st, 3rd, and 7th day of ICU stay (P < 0.05). The Pcv-aCO2/Ca-cvO2 of the death group was higher than that of the survival group on the 3rd and 7th day of ICU stay (P < 0.05). Logistic model results showed that age, SOFA score, APACHE II score, the number of multiple organ failure (MODS), intracranial infection, the increase of Pcv-aCO2, Pcv-aCO2/Ca-cvO2, and the increase of lactic acid were independent risk factors for death in patients with septic shock (OR values were 1.519, 1.808, 1.781, 1.912, 2.069, 1.848, 1.781, and 1.642, respectively, P < 0.05). The results showed that the AUC value of Pcv-aCO2 in predicting death was 0.943, and the sensitivity and specificity were 93.72% and 83.09%, respectively. The AUC value of Pcv-aCO2/Ca-cvO2 for predicting death was 0.887, and the sensitivity and specificity were 81.63% and 77.56%, respectively. The AUC value of lactic acid in predicting death of patients was 0.825, and the sensitivity and specificity were 71.66% and 82.09%, respectively. Conclusion Changes of microcirculation flow tissue perfusion parameters and blood lactic acid level changes are closely related to the prognosis of patients with septic shock, which is of great value in the evaluation of the prognosis of patients with septic shock.

Characteristics of sublingual microcirculatory changes during the early postoperative period following cardiopulmonary bypass-assisted cardiac surgery-a prospective cohort study.

Persistent microcirculatory dysfunction associated with increased morbidity and mortality. Interventions in the early resuscitation can be tailored to the changes of microcirculation and patient's need. However, there is usually an uncoupling of macrocirculatory and microcirculatory hemodynamics during resuscitation. Current research on the patterns of microcirculatory changes and recovery after cardiopulmonary bypass (CPB)-assisted cardiac surgery is limited. This study aimed to analyze changes in the microcirculatory parameters after CPB and their correlation with macrocirculation and to explore the characteristics of microcirculatory changes following CPB-assisted cardiac surgery. Between December 2018 and January 2019, 24 adult patients with indwelling pulmonary artery catheters after elective cardiac surgery using CPB were enrolled in this study. Both microcirculatory and macrocirculatory parameters were collected at 0, 6, 16, and 24 hours after admission to the intensive care unit (ICU). Video images of sublingual microcirculation were analyzed to obtain the microcirculatory parameters, including total vascular density (TVD), perfused small vessel density (PSVD), the proportion of perfused small vessels (PPV), microvascular flow index (MFI), and flow heterogeneity index (HI). The characteristics of microcirculatory parameter change following cardiac surgery and the correlation between microcirculatory parameters and macroscopic hemodynamic indicators, oxygen metabolic indicators, and carbon dioxide partial pressure difference (PCO2gap) were analyzed. There were significant differences in the changes of TVD (P=0.012) and PSVD (P=0.005) during the first 24 hours postoperatively in patients who underwent CPB-assisted cardiac surgery. The microcirculatory density parameters (TVD: r=-0.5059, P=0.0456; PVD: r=-0.5499, P=0.0273) were correlated with oxygen delivery index (DO2I) at 24 hours after surgery. The microcirculatory flow parameters (PPV: r=0.4370, P=0.0327; MFI: r=0.6496, P=0.0006; and HI: r=-0.5350, P=0.0071) had a strong correlation with PCO2gap at 0 hour after surgery. TVD and PSVD might be two most sensitive indicators affected by CPB-assisted cardiac surgery. There was no consistency between microcirculation and macrocirculation until 24 hours following cardiac surgery, meaning the improvement of systemic hemodynamic indicators does not guarantee correspondently improvement in microcirculation. Early controlled oxygen supply after CPB-assisted cardiac surgery may be conducive to the resuscitation of patients to a certain extent.

Renal Resistive Index on Intensive Care Unit Admission Correlates With Tissue Hypoperfusion Indices and Predicts Clinical Outcome.

Renal resistive index (RRI) has been used to evaluate renal blood flow. Our aim was to investigate the relation between RRI and global tissue hypoperfusion indices and their association with clinical outcome, in intensive care unit (ICU) patients. RRI was measured within 24 h of ICU admission. Gas exchange and routine hemodynamic variables at the time of RRI assessment were recorded. An elevated RRI was defined as >0.7. The ratio of central venous-to-arterial carbon dioxide partial pressure difference by arterial-to-central venous oxygen content difference (P(cv-a)CO2/C(a-cv)O2) and lactate were used as global tissue hypoperfusion indices. A total of 126 patients were included [median age 61 (IQR 28) years, 74% males]. P(cv-a)CO2/C(a-cv)O2 ratio and arterial lactate were significantly higher in patients with RRI >0.7 compared with those with RRI ≤0.7 [2.88 (3.39) vs. 0.62 (0.57) mmol/L and 2.4 (2.2) vs. 1.2 (0.6)] respectively, both P < 0.001)]. RRI was significantly correlated with P(cv-a)CO2/C(a-cv)O2 ratio and arterial lactate for the whole patient population (rho = 0.64, both P < 0.0001) and for the subset of patients with shock (rho = 0.47, P = 0.001; and r = 0.64, P < 0.0001 respectively). Logistic regression models showed a significant association between RRI and P(cv-a)CO2/C(a-cv)O2 ratio with clinical outcome. The combination of RRI with P(cv-a)CO2)/(C(a-cv)O2 ratio and lactate better predicted mortality than RRI alone [AUC 84.8% (95% CI 5.1% -94.4%)] vs. [AUC 74.9% (95% CI 61%-88.8%)] respectively, P < 0.001. Renal blood flow assessed by RRI, on ICU admission, correlates with global tissue hypoperfusion indices. In addition, RRI in combination with tissue perfusion estimation better predicts clinical outcome than RRI alone.

Cerebral and Systemic Stress Parameters in Correlation with Jugulo-Arterial CO2 Gap as a Marker of Cerebral Perfusion during Carotid Endarterectomy.

Intraoperative stress is common to patients undergoing carotid endarterectomy (CEA); thus, impaired oxygen and metabolic balance may appear. In this study, we aimed to identify new markers of intraoperative cerebral ischemia, with predictive value on postoperative complications during CEA, performed in regional anesthesia. A total of 54 patients with significant carotid stenosis were recruited and submitted to CEA. Jugular and arterial blood samples were taken four times during operation, to measure the jugulo-arterial carbon dioxide partial pressure difference (P(j-a)CO2), and cortisol, S100B, L-arginine, and lactate levels. A positive correlation was found between preoperative cortisol levels and all S100B concentrations. In addition, they are positively correlated with P(j-a)CO2 values. Conversely, postoperative cortisol inversely correlates with P(j-a)CO2 and postoperative S100B values. A negative correlation was observed between maximum systolic and pulse pressures and P(j-a)CO2 after carotid clamp and before the release of clamp. Our data suggest that preoperative cortisol, S100B, L-arginine reflect patients’ frailty, while these parameters postoperatively are influenced by intraoperative stress and injury. As a novelty, P(j-a)CO2 might be an emerging indicator of cerebral blood flow during CEA.

Evaluation of Central Venous-to-Arterial Carbon Dioxide Partial Pressure Difference in Patients with Emergency Surgery for Bowel Obstruction

Evaluation of Central Venous-to-Arterial Carbon Dioxide Partial Pressure Difference in Patients with Emergency Surgery for Bowel Obstruction

Elevated Arterial-Central Venous Carbon Dioxide Partial Pressure Difference Indicates Poor Prognosis in the Early Postoperative Period of Open Heart Surgery in Infants with Congenital Heart Disease.

Elevated arterial-central venous carbon dioxide partial pressure difference (AVCO2) may be an important marker to predict tissue and organ hypoperfusion in adults. We analyzed the hemodynamic data of infants with congenital heart disease who underwent corrective repair with cardiopulmonary bypass (CPB) to identify whether AVCO2 has clinical significance in early postoperative tissue hypoperfusion, occurrence of complications, and clinical outcomes. Infants with clinical conditions of hypoperfusion, without volume responsiveness and with ineffective initial treatment, within 3h of cardiac surgery were enrolled in this study. A pulse contour cardiac output catheter was used to monitor the cardiac index (CI). Eight measurements of arterial blood gas and central venous blood gas were taken within 42h after surgery. Clinical data of all patients were recorded. A total of 69 children were enrolled in this study. Arteriovenous oxygen difference, AVCO2, lactic acid level, and vasoactive inotropic score in the hypoperfusion group (oxygen supply/oxygen consumption ratio [DO2/VO2] of ≤ 2) were significantly higher than those in the non-hypoperfusion group (DO2/VO2 > 2), while the CI in the hypoperfusion group was significantly lower than that in the non-hypoperfusion group. The cutoff value of AVCO2 to predict DO2/VO2 ≤ 2 was 12.3 within 42h of surgery with area under the curve of 0.84. High AVCO2 is more likely to be associated with some complications and prolonged mechanical ventilation and length of stay in the intensive care unit. Elevated AVCO2 within 42h of CPB in infants is associated with tissue and organ hypoperfusion and incidence of complications. Persistent or repeated increase in AVCO2 indicates poor prognosis.

The Ability of Carbon Dioxide–Derived Indices to Predict Adverse Outcome After Cardiac Surgery

The objective of this study was to assess whether the central venous-to-arterial carbon dioxide partial-pressure difference (ΔPCO2) and the ratio of the ΔPCO2 to the arterial-venous difference in oxygen content (ΔPCO2/Ca-vO2) predict postoperative complications (PC) after cardiac surgery. Prospective, observational, noninterventional study. The study comprised 60 patients undergoing cardiac surgery with cardiopulmonary bypass. The primary endpoint was the occurrence of PC. Data were first analyzed in two groups based on the occurrence of PC. Then, receiver operating characteristic curves of the ΔPCO2 and the ΔPCO2/Ca-vO2 ratio were analyzed for the prediction of PC. Among the study participants, 22 (36.7%) experienced PC. The death rate was 18.3%. The present study found that the ΔPCO2 and the ΔPCO2/Ca-vO2 ratio predicted the occurrence of PC with areas under the curve of 0.702 and 0.666, respectively. The best thresholds of these markers were 8.3 mmHg for the ΔPCO2 and 2.16 mmHg/mL for the ΔPCO2/Ca-vO2 ratio. A significant difference was found for these indicators between the groups with and without PC. The ΔPCO2 and the ΔPCO2/Ca-vO2 ratio were significantly correlated to EuroSCORE II, duration of aortic clamping, majority of prognostic scores the first two days postoperatively, and the lactate level. The ΔPCO2/Ca-vO2 ratio is predictive of hyperlactatemia >2 mmol/L, with an area under the curve of 0.787. The ΔPCO2 and the ΔPCO2/Ca-vO2 ratio predict the occurrence of complications in cardiac surgery.

Central venous-to-arterial CO2 difference is a poor tool to predict adverse outcomes after cardiac surgery: a retrospective study.

PurposeThe venous-to-arterial carbon dioxide partial pressure difference (CO2 gap) has been reported to be a sensitive indicator of cardiac output adequacy. We aimed to assess whether the CO2 gap can predict postoperative adverse outcomes after cardiac surgery.MethodsA retrospective study was conducted of 5,151 patients from our departmental database who underwent cardiac surgery from 1 January 2008 to 31 December 2018. Lactate level (mmol·L−1), central venous oxygen saturation (ScVO2) (%), and the venous-to-arterial carbon dioxide difference (CO2 gap) were measured at intensive care unit (ICU) admission and on days 1 and 2 after cardiac surgery. The following postoperative adverse outcomes were collected: ICU mortality, hemopericardium or tamponade, resuscitated cardiac arrest, acute kidney injury, major bleeding, acute hepatic failure, mesenteric ischemia, and pneumonia. The primary outcome was the presence of at least one postoperative adverse outcome. Logistic regression was used to assess the association between ScVO2, lactate, and the CO2 gap with adverse outcomes. Their diagnostic performance was compared using a receiver operating characteristic (ROC) curve.ResultsThere were 1,933 patients (38%) with an adverse outcome. Cardiopulmonary bypass (CPB) parameters were similar between groups. The CO2 gap was slightly higher for the “adverse outcomes” group than for the “no adverse outcomes” group. Arterial lactate at admission, day 1, and day 2 was also slightly higher in patients with adverse outcomes. Central venous oxygen saturation was not significantly different between patients with and without adverse outcomes. The area under the ROC curve to predict outcomes after CPB for the CO2 gap at admission, day 1, and day 2 were 0.52, 0.55, and 0.53, respectively.ConclusionAfter cardiac surgery with CPB, the CO2 gap at ICU admission, day 1, and day 2 was associated with postoperative adverse outcomes but showed poor diagnostic performance.

Arterial and end-tidal carbon dioxide partial pressure difference during prehospital anaesthesia in critically ill patients.

Normoventilation is crucial for many critically ill patients. Ventilation is routinely guided by end-tidal capnography during prehospital anaesthesia, based on the assumption of the gap between arterial partial pressure of carbon dioxide (PaCO2 ) and end-tidal carbon dioxide partial pressure (PetCO2 ) of approximately 0.5kPa (3.8mmHg). We retrospectively analysed the airway registry and patient chart data of patients who had been anaesthetised and intubated endotracheally by the prehospital critical care team and had their prehospital arterial blood gases analysed. Bland-Altman analysis was used to estimate the bias and limits of agreement. Altogether 502 patients were included in the study, with a median age of 58years. The most common patient groups were post-resuscitation (155, 31%), neurological emergencies (96, 19%), intoxication (75, 15%) and trauma (68, 14%). The median of the gap between PaCO2 and PetCO2 was 1.3kPa (interquartile range 0.7 to 2.2) (9.8 (5.3-16.5) mmHg). Mean bias of PetCO2 was -1.6kPa/12.0mmHg (standard deviation 1.7kPa/12.8mmHg) with 95% confidence limits of agreement -4.9 to 1.9kPa (-36.8 to 14.3mmHg). The gap was≥1.0kPa (>7.5mmHg) in 297 (66%, 95% confidence interval 55 to 63) patients. Our results suggest that end-tidal capnography alone might not be an adequate method to achieve normoventilation for critically ill patients intubated and mechanically ventilated in prehospital setting. Thus, an arterial blood gas analysis might be useful to recognize patients with an increased gap between PaCO2 and PetCO2 .

Effect of shenfu injection on microcirculation in shock patients: A protocol for systematic review and meta-analysis.

Background:Shock is a major public health problem worldwide. At present, the morbidity and mortality of shock patients are relatively high. Vasomotor dysfunction is 1 of the key pathological aspects of shock. Shenfu injection has been widely used for the treatment of shock in China. Pharmacological studies have suggested that Shenfu injection can reduce peripheral circulation resistance and improve microcirculation. The purpose of this study is to evaluate the effect and safety of Shenfu injection on the microcirculation of patients with shock.Methods:This review summarizes and meta-analyzes randomized controlled trials of Shenfu injection for the treatment of shock.Searched the following electronic databases: PubMed, Cochrane Library, Embase, CNKI, VIP and Wanfang Data. The Cochrane risk assessment tool was used to evaluate the methodological quality of randomized controlled trials. All tests are analyzed according to the standards of the Cochrane Handbook. Review Manager 5.3, R-3.5.1 software and Grading of Recommendations Assessment, Development, and Evaluation pro GDT web solution are used for data synthesis and analysis.Results:This review focuses on the effects of Shenfu injection on the microcirculation of shock patients (blood lactic acid level, arteriovenous oxygen saturation, arteriovenous carbon dioxide partial pressure difference, sublingual microcirculation), 28-day mortality, 28-day ICU hospitalization and adverse reaction rate.Conclusion:This review provides a clear basis for evaluating the impact of Shenfu injection on the microcirculation of shock patients, as well as the effectiveness and safety of the treatment.

Preliminary study on effect of intraoperative goal-directed fluid management on pulmonary function and oxygen dynamics in patients with severe burns

Objective: To preliminarily investigate the effect of intraoperative goal-directed fluid management (GDFM) on pulmonary function and oxygen dynamics in patients with severe burns. Methods: From February 2017 to May 2018, 30 patients admitted to Burn Department of our hospital with severe burns who met the criteria for inclusion and needed escharectomy and skin grafting were enrolled in this prospective randomized controlled trial. The patients were divided into group GDFM of 15 cases [14 males and 1 female, (45±14) years old] and conventional liquid management group of 15 cases [12 males and 3 females, (42±10) years old] according to the random number table. During escharectomy and skin grafting, volume of patients in group GDFM was managed according to the GDFM scheme, based on cardiac output index, stroke volume variation, stroke volume index, hemoglobin, central venous oxygen saturation (ScvO(2)), and other parameters; volume of patients in conventional liquid management group was managed according to clinical experience and conventional liquid management scheme, based on mean arterial pressure, central venous pressure, urine output, hemoglobin, and other parameters. At post operation hour (POH) 1, 6, 12, and 24, arterial and venous blood was collected from patients of the two groups to determine the levels of extravascular lung water index (ELWI), global end-diastolic volume index (GEDI), oxygenation index, ScvO(2), central venous-to-arterial blood carbon dioxide partial pressure difference (Pcv-aCO(2)), lactic acid, pH value, bicarbonate ion, and base excess routinely. Data were processed with Fisher's exact probability test, t test, analysis of variance for repeated measurement, and least significant difference test. Results: (1) The ELWI of patients in group GDFM was (4.3±1.1) mL/kg at POH 1, which was significantly lower than (6.5±3.6) mL/kg in conventional liquid management group (t=2.26, P<0.05). The ELWI levels of patients in group GDFM at POH 6, 12, and 24 were (6.8±2.2), (6.6±2.0), and (6.9±1.6) mL/kg, respectively, significantly higher than the level at POH 1 within the same group (P<0.01), and similar to (8.5±3.1), (7.8±2.3), and (8.0±3.5) mL/kg in conventional liquid management group (t=1.73, 1.53, 1.10, P>0.05). The GEDI levels between patients of the two groups were similar, and there was no significantly statistical difference between the two groups as a whole (treatment factor main effect F=2.35, time factor main effect F=0.44, interaction F=0.07, P>0.05). (2) The oxygenation index of patients in group GDFM was (350±78) mL/kg at POH 1, which was significantly higher than (259±109) mL/kg in conventional liquid management group (t=2.63, P<0.05). In conventional liquid management group, the oxygenation index of patients at POH 6 was significantly higher than that at POH 1, 12, or 24 (P<0.01). The ScvO(2) levels of patients in group GDFM at POH 1, 6, and 12 were 0.516±0.105, 0.679±0.121, and 0.713±0.104, respectively, which were significantly higher than 0.382±0.194, 0.545±0.194, and 0.595±0.191 in conventional liquid management group (t=2.35, 2.27, 2.10, P<0.05). The ScvO(2) levels of patients in the two groups at POH 6, 12, and 24 were significantly higher than those levels at POH 1 within the same group (P<0.01), and the ScvO(2) of patients in conventional liquid management group at POH 24 was significantly higher than that at POH 6 or 12 within the same group (P<0.05 or P<0.01). The Pcv-aCO(2) levels of patients in group GDFM were significantly lower than those in conventional liquid management group at POH 1 and 6 (t=2.55, 2.71, P<0.05). The Pcv-aCO(2) of patients in group GDFM at POH 12 was significantly lower than that at POH 6 or 24 within the same group (P<0.05). (3) The blood lactic acid levels and pH values between patients of the two groups were similar at POH 1, 6, 12, and 24 (t=0.89, 0.19, 0.26, 0.23; 1.55, 0.71, 0.77, 0.77, P>0.05). In conventional liquid management group, the blood lactic acid levels of patients at POH 6, 12, and 24 were significantly lower than the level at POH 1 within the same group (P<0.05), and the pH values of patients at POH 6, 12, and 24 were significantly higher than the value at POH 1 within the same group (P<0.05). The levels of bicarbonate ion and base excess between patients of the two groups were similar, and there were no significantly statistical differences between the two groups as a whole (treatment factor main effect F=0.06, 0.11, time factor main effect F=2.07, 1.59, interaction F=1.45, 0.91, P>0.05). Conclusions: GDFM is helpful to improve the pulmonary function and oxygen dynamics in patients with severe burns in the short term after escharectomy and skin grafting. It has certain significance in preventing and reducing pulmonary edema and pulmonary complications in patients with severe burn after operation.

Venous-to-Arterial Carbon Dioxide Partial Pressure Difference: Predictor of Septic Patient Prognosis Depending on Central Venous Oxygen Saturation.

This study aimed to assess the viability of using the venous-to-arterial carbon dioxide partial pressure difference (P(v-a)CO2) to predict clinical worsening of septic shock, depending on central venous oxygen saturation (ScvO2). The prospective, observational, multicentric study conducted in three intensive care units (ICUs) included all patients with a septic shock episode during the first 6 h, with 122 patients assessed. Clinical worsening was defined as an increase of sequential organ failure assessment (SOFA) scores ≥1 (ΔSOFA ≥1) within 2 days. To assess the ability of P(v-a)CO2 to predict clinical worsening, univariate and multivariate analyses were performed according to ΔSOFA. A receiver-operating characteristic (ROC) analysis was used to confirm model predictions. Associations between P(v-a)CO2 and mortality were explored using correlations. Using multivariate analyses, two independent factors associated with ΔSOFA at least 1 were identified: an averaged 6-h value of lactate concentration (Lac [1-6]) (odds ratios [ORs], 2.43 [95% confidence interval, CI, 1.20-4.89]; P = 0.013) and an averaged 6-h value of P(v-a)CO2 (P(v-a)CO2 [1-6]) (OR, 1.49 [95% CI, 1.04-2.15]; P = 0.029). ROC analysis confirmed that Lac [1-6] and P(v-a)CO2 [1-6] were significantly associated with ΔSOFA at least 1, whereas ScvO2 [1-6] was not. Finally, ΔSOFA at least 1 was associated with higher 28-day (76% vs. 10%, P = 0.001) and ICU (83% vs. 12%, P = 0.001) mortality rates, which were higher in patients with P(v-a)CO2 [1-6] more than 5.8 mmHg (57% vs. 33%; P = 0.012). In conclusion, P(v-a)CO2 may help predict outcomes for septic shock patients regardless of ScvO2 values.

Predictive value of central venous-to-arterial carbon dioxide partial pressure difference for fluid responsiveness in septic shock patients: a prospective clinical study

To evaluate the accuracy of central venous-to-arterial carbon dioxide partial pressure difference (Pcv-aCO2) before and after rapid rehydration test (fluid challenge) in predicting the fluid responsiveness in patients with septic shock. A prospective observation was conducted. Forty septic shock patients admitted to medical intensive care unit (ICU) of Peking Union Medical College Hospital from October 2015 to June 2017 were enrolled. All of the patients received fluid challenge in the presence of invasive hemodynamic monitoring. Heart rate (HR), blood pressure, cardiac index (CI), Pcv-aCO2 and other physiological variables were recorded at 10 minutes before and immediately after fluid challenge. Fluid responsiveness was defined as an increase in CI greater than 10% after fluid challenge, whereas fluid non-responsiveness was defined as no increase or increase in CI less than 10%. The correlation between Pcv-aCO2 and CI was explored by Pearson correlation analysis. Receiver operating characteristic (ROC) curves were established to evaluate the discriminatory abilities of baseline and the changes after fluid challenge in Pcv-aCO2 and other physiological variables to define the fluid responsiveness. The patients were separated into two groups according to the initial value of Pcv-aCO2. The cut-off value of 6 mmHg (1 mmHg = 0.133 kPa) was chosen according to previous studies. The discriminatory abilities of baseline and the change in Pcv-aCO2 (ΔPcv-aCO2) were assessed in each group. A total of 40 patients were finally included in this study. Twenty-two patients responded to the fluid challenge (responders). Eighteen patients were fluid non-responders. There was no significant difference in baseline physiological variable between the two groups. Fluid challenge could increase CI and blood pressure significantly, decrease HR notably and had no effect on Pcv-aCO2 in fluid responders. In non-responders, blood pressure was increased significantly and CI, HR, Pcv-aCO2 showed no change after fluid challenge. Pcv-aCO2 was comparable in responders and non-responders. In 40 patients, CI and Pcv-aCO2 was inversely correlated before fluid challenge (r = -0.391, P = 0.012) and the correlation between them weakened after fluid challenge (r = -0.301, P = 0.059). There was no significant correlation between the changes in CI and Pcv-aCO2 after fluid challenge (r = -0.164, P = 0.312). The baseline Pcv-aCO2 and ΔPcv-aCO2 could not discriminate between responders and non-responders, with the area under ROC curve (AUC) of 0.50 [95% confidence interval (95%CI) = 0.32-0.69] and 0.51 (95%CI = 0.33-0.70), respectively. HR and blood pressure before fluid challenge and their changes after fluid challenge showed very poor discriminative performances. Before fluid challenge, 16 patients had a Pcv-aCO2 > 6 mmHg. Their mean CI was significantly lower and Pcv-aCO2 was significantly higher than that in 24 patients whose Pcv-aCO2 ≤ 6 mmHg [n = 24; CI (mL×s-1×m-2): 48.3±11.7 vs. 65.0±18.3, P < 0.01; Pcv-aCO2 (mmHg): 8.4±1.9 vs. 2.9±2.8, P < 0.01]. Pcv-aCO2 was decreased significantly after fluid challenge in patients with an initial Pcv-aCO2 > 6 mmHg and their ΔPcv-aCO2 was notably different as compared with the patients whose baseline Pcv-aCO2 ≤ 6 mmHg (mmHg: -3.8±3.4 vs. 0.9±2.9, P < 0.01). 68.8% (11/16) patients responded to the fluid challenge in patients with an initial Pcv-aCO2 > 6 mmHg. The AUC of the baseline Pcv-aCO2 and ΔPcv-aCO2 to define fluid responsiveness was 0.85 (95%CI = 0.66-1.00) and 0.84 (95%CI = 0.63-1.00), respectively, and the positive predictive value was 1 when the cut-off value was 8.0 mmHg and -4.2 mmHg, respectively. 45.8% (11/24) patients responded to the fluid challenge in patients whose baseline Pcv-aCO2 ≤ 6 mmHg. There was no predictive value of baseline Pcv-aCO2 and ΔPcv-aCO2 on fluid responsiveness. Pcv-aCO2 and its change cannot serve as a surrogate of the change in cardiac output to define the response to fluid challenge in septic shock patients whose baseline Pcv-aCO2 ≤ 6 mmHg, while the predictive values of baseline Pcv-aCO2 and the change in Pcv-aCO2 are presented in patients with the initial value of Pcv-aCO2 > 6 mmHg. Clinical Trials, NCT01941472.

Experimental animal study of cerebral oxygen metabolism changes during the process of brain death

To reproduce a stable animal model of brain death in pigs, observe the change regularity of cerebral oxygen metabolism during the process of brain death, and to evaluate the significance and value of cerebral oxygen metabolism parameters for the diagnosis of brain death. Twelve landrace pigs were used to create the brain death models using modified method of increasing epidural intracranial pressure (ICP). The mean arterial pressure (MAP) and ICP were monitored continuously during the process. The pigs were divided into four groups according to cerebral perfusion pressure (CPP) decreasing degree during brain death, namely CPP normal group and CPP decreasing 0%-30%, 30%-70%, and 70%-100% groups. Blood gas analysis of the external carotid artery and internal jugular vein were monitored discontinuously. The changes in cerebral oxygen metabolism parameters, including external carotid artery-internal jugular vein bulb oxygen content difference (AJDO2), internal jugular bulb-external carotid artery carbon dioxide partial pressure difference (DPCO2) and DPCO2/AJDO2 ratio, were observed. Brain death model were successfully reproduced in 12 experimental pigs. With MAP and ICP monitoring, the models at different stages of CPP could be repeatedly induced. The levels of AJDO2 and DPCO2 were increased gradually and then decreased, while the ratio of DPCO2/AJDO2 was constantly increased with the decrease of CPP. The level of AJDO2 in CPP decreasing 0%-30% group was significantly higher than that in CPP normal group [(5.86±1.21)% vs. (3.92±0.64)%], the levels of DPCO2 in CPP decreasing 0%-30% and CPP decreasing 30%-70% groups were significantly higher than those in CPP normal group [mmHg (1 mmHg = 0.133 kPa): 10.33±1.83, 11.48±2.32 vs. 6.11±1.43], and the ratios of DPCO2/AJDO2 in CPP decreasing 30%-70% and CPP decreasing 70%-100% groups were significantly higher than those in CPP normal group and CPP decreasing 0%-30% group (2.81±0.53, 4.12±1.07 vs. 1.57±0.64, 1.62±0.81). All the differences above were statistically significant (all P < 0.05). With the decrease of CPP, cerebral oxygen metabolism showed a regular change during brain death. DPCO2 combined with DPCO2/AJDO2 is a reliable blood gas analysis index indicating intracranial hypoperfusion, which has certain reference value for the determination of brain death.