Performance of the decarboxylation index to predict CO2 removal and minute ventilation reduction under extracorporeal respiratory support.

BACKGROUND: The aim of this study was to assess the interdependence of extracorporeal blood flow (Qec) and gas flow (GF) in predicting CO2 removal and reduction of minute mechanical ventilation under extracorporeal respiratory support. METHODS: All patients who benefited from V-V ECMO and high-flow ECCO2 R in our intensive care unit over a period of 18 months were included. CO2 removal was calculated from inlet/outlet blood port gases during the first 7 days of oxygenator use. The relationship between the Qec × GF product (named decarboxylation index and expressed in L2 /min2 ) and CO2 removal or expired minute mechanical ventilation reduction (EC MV ratio) was studied using linear regression models. RESULTS: Eighteen patients were analyzed, corresponding to 24 oxygenators and 261 datasets. CO2 removal was 393 ml/min (IQR, 310-526) for 1.8 m2 oxygenators and 179 ml/min (IQR, 165-235) for 1.3 m2 oxygenators. The decarboxylation index was associated linearly with CO2 removal (R2  = 0.62 and R2  = 0.77 for the two oxygenators, respectively) and EC MV ratio (R2  = 0.72 and R2  = 0.62, respectively). The 20L2 /min2 value (considering Qec = 2 L/min and GF = 10 L/min) was associated with an EC MV ratio between 61% and 29% for 1.8 m2 oxygenators, and between 62% and 38% for 1.3 m2 oxygenators. CONCLUSION: The decarboxylation index is a simple parameter to predict CO2 removal and EC MV ratio under extracorporeal respiratory support.

Continuous peripheral nerve blocks for analgesia of ventilated critically ill patients with multiple trauma: a prospective randomized study.

BACKGROUND: Sedation of ventilated critically ill trauma patients requires high doses of opioids and hypnotics. We aimed to compare the consumption of opioids and hypnotics, and patient outcomes using sedation with or without continuous regional analgesia (CRA). METHODS: Multiple trauma-ventilated patients were included. The patients were randomized to receive an intravenous analgesia (control group) or an addition of CRA within 24h of admission. A traumatic brain injury (TBI) patients group was analyzed. The primary endpoint was the cumulative consumption of sufentanil at 2 days of admission. Secondary endpoints were cumulative and daily consumption of sufentanil and midazolam, duration of mechanical ventilation, intensive care unit (ICU) stay, and safety of CRA management. RESULTS: Seventy six patients were analyzed: 40 (67.5% males) in the control group and 36 (72% males) in the CRA group, respectively. The median [IQR] Injury Severity Score was 30.5 [23.5-38.5] and 26.0 [22.0-41.0]. The consumption of sufentanil at 48h was 725 [465-960] µg/48h versus 670 [510-940] µg/48h (p = 0.16). Daily consumption did not differ between the groups except on day 1 when consumption of sufentanil was 360 [270-480] µg vs. 480 [352-535] µg (p = 0.03). Consumptions of midazolam did not differ between the groups. No difference was noted between the groups according to the secondary endpoints. CONCLUSIONS: CRA does not decrease significantly sufentanil and midazolam consumption within the first 5 days after ICU admission in multiple trauma-ventilated patients. The use of peripheral nerve blocks in heavily sedated and ventilated trauma patients in the ICU seems safe.

Mathematical modelling of oxygenation under veno-venous ECMO configuration using either a femoral or a bicaval drainage.

BACKGROUND: The bicaval drainage under veno-venous extracorporeal membrane oxygenation (VV ECMO) was compared in present experimental study to the inferior caval drainage in terms of systemic oxygenation. METHOD: Two mathematical models were built to simulate the inferior vena cava-to-right atrium (IVC → RA) route and the bicaval drainage-to-right atrium return (IVC + SVC → RA) route using the following parameters: cardiac output (QC), IVC flow/QC ratio, venous oxygen saturation, extracorporeal pump flow (QEC), and pulmonary shunt (PULM-Shunt) to obtain pulmonary artery oxygen saturation (SPAO2) and systemic blood oxygen saturation (SaO2). RESULTS: With the IVC → RA route, SPAO2 and SaO2 increased linearly with QEC/QC until the threshold of the IVC flow/QC ratio, beyond which the increase in SPAO2 reached a plateau. With the IVC + SVC → RA route, SPAO2 and SaO2 increased linearly with QEC/QC until 100% with QEC/QC = 1. The difference in required QEC/QC between the two routes was all the higher as SaO2 target or PULM-Shunt were high, and occurred all the earlier as PULM-Shunt were high. The required QEC between the two routes could differ from 1.0 L/min (QC = 5 L/min) to 1.5 L/min (QC = 8 L/min) for SaO2 target = 90%. Corresponding differences of QEC for SaO2 target = 94% were 4.7 L/min and 7.9 L/min, respectively. CONCLUSION: Bicaval drainage under ECMO via the IVC + SVC → RA route gave a superior systemic oxygenation performance when both QEC/QC and pulmonary shunt were high. The VV-V ECMO configuration (IVC + SVC → RA route) might be an attractive rescue strategy in case of refractory hypoxaemia under VV ECMO.

Structural recirculation and refractory hypoxemia under femoro-jugular veno-venous extracorporeal membrane oxygenation.

The performance of each veno-venous extracorporeal membrane oxygenation (vv-ECMO) configuration is determined by the anatomic context and cannula position. A mathematical model was built considering bicaval specificities to simulate femoro-jugular configuration. The main parameters to define were cardiac output (QC ), blood flow in the superior vena cava (QSVC ), extracorporeal pump flow (QEC ), and pulmonary shunt (kS-PULM ). The obtained variables were extracorporeal flow ratio in the superior vena cava (EFRSVC  = QEC /[QEC  + QSVC ]), recirculation coefficient (R), effective extracorporeal pump flow (Qeff-EC  = [1 - R] × QEC ), Qeff-EC /QC ratio, and arterial blood oxygen saturation (SaO2 ). EFRSVC increased logarithmically when QEC increased. High QC or high QSVC /QC decreased EFRSVC (range, 68%-85% for QEC of 5 L/min). R also increased following a logarithmic shape when QEC increased. The R rise was earlier and higher for low QC and high QSVC /QC (range, 12%-49% for QEC of 5 L/min). The Qeff-EC /QC ratio (between 0 and 1) was equal to EFRSVC for moderate and high QEC . The Qeff-EC /QC ratio presented the same logarithmic profile when QEC increased, reaching a plateau (range, 0.67-0.91 for QEC /QC  = 1; range, 0.75-0.94 for QEC /QC  = 1.5). The Qeff-EC /QC ratio was linearly associated with SaO2 for a given pulmonary shunt. SaO2  < 90% was observed when the pulmonary shunt was high (Qeff-EC /QC  ≤ 0.7 with kS-PULM  = 0.7 or Qeff-EC /QC  ≤ 0.8 with kS-PULM  = 0.8). Femoro-jugular vv-ECMO generates a systematic structural recirculation that gradually increases with QEC . EFRSVC determines the Qeff-EC /QC ratio, and thereby oxygen delivery and the superior cava shunt. EFRSVC cannot exceed a limit value, explaining refractory hypoxemia in extreme situations.

Clinical value of automated fibrin generation markers in patients with septic shock: a SepsiCoag ancillary study.

An ancillary analysis to the SepsiCoag multicentric prospective observational study on patients entering an intensive care unit with septic shock evaluated the prognostic potential of fibrin generation markers (FGMs) tested at inclusion in the study, on survival at day 30. After centralization of samples, three automated FGMs were compared: D-dimers (DDi), fibrin/fibrinogen degradation products (FDP) and fibrin monomers (FM). FM was the single FGM that was significantly higher in non-surviving patients, area under the receiver-operator characteristic curve (AUCROC ): 0·617, P < 0·0001. Significantly higher International Society on Thrombosis and Haemostasis Disseminated Intravascular Coagulation (ISTH DIC) scores were calculated in non-survivors using each of the three FGMs. A dose-effect relationship was observed between ISTH DIC scores and non-survival, with highest significance obtained using FM as the FGM. An overt DIC diagnosis using the ISTH DIC score calculated using FM was a predictor of non-survival at day 30, independently from overt DIC diagnosis based on scores calculated using FDP or DDi. The AUCROC values testing the ability of the ISTH DIC score to predict non-survival were 0·650, 0·624 and 0·602 using FM, DDi and FDP, respectively, as the FGM. In patients with septic shock, among the commercially-available automated assays, automated FM is the FGM best related with late prognosis.

Modelling the association between fibrinogen concentration on admission and mortality in patients with massive transfusion after severe trauma: an analysis of a large regional database.

BACKGROUND: The relationship between fibrinogen concentration and traumatic death has been poorly explored after severe trauma. Existing studies analysed this relationship in unselected trauma population, often considering fibrinogen concentration as a categorical variable. The aim of our study was to model the relationship between fibrinogen concentration and in-hospital mortality in severe trauma patients requiring massive transfusion using fibrinogen on admission as a continuous variable. METHODS: We designed a retrospective observational study based on prospectively collected data from 2009 to 2015 in seven French level-I trauma centres. All consecutive patients requiring a transfusion of at least 10 packed red blood cells (RBC) within 24 h were included. To assess the relationship between in-hospital death and fibrinogen concentration on admission, we performed generalized linear and additive models with death as a dependent variable. We also assessed the relationship between fibrinogen concentration below 1.5 g.L- 1 and potential predictors. RESULTS: Within the study period, 366 patients were included. A non-linear relationship was found between fibrinogen concentration and death. Graphical modelling of this relationship depicted a negative association between fibrinogen levels and death below a fibrinogen concentration of 1.5 g.L- 1. Predictors of low fibrinogen concentration (< 1.5 g.L- 1) were systolic blood pressure, Glasgow coma scale and haemoglobin concentration on admission. CONCLUSIONS: A complex and robust approach for modelling the relationship between fibrinogen and mortality revealed a critical fibrinogen threshold of 1.5 g.L- 1 for severe trauma patients requiring massive transfusion. This trigger may guide the administration of procoagulant therapies in this context.

Diagnostic performance of prothrombin time point-of-care to detect acute traumatic coagulopathy on admission: experience of 522 cases in trauma center.

BACKGROUND: Early identification of acute traumatic coagulopathy is a key challenge during initial management to determine whether to initiate early hemostatic support. We assessed the performance of prothrombin time (PT) at point-of-care in trauma patients to detect moderate and severe coagulopathy on admission. STUDY DESIGN AND METHODS: All admitted consecutive trauma patients were analyzed retrospectively between April 2014 and July 2015. PT was measured on admission with both a PT point-of-care device (PTr-CGK) and a standard coagulation test (PTr-STD). The results for PTr-CGK and PTr-STD were compared using analysis of agreement, precision, and accuracy. The diagnostic performance of PTr-CGK to predict coagulopathy was established by analysis of receiver operating characteristic curves. The predictive performance of different thresholds and risk factors for misclassification were also studied. RESULTS: Over a 16-month period, 522 patients were included. PTr-CGK estimated PTr-STD with a bias of 0.00 (95% confidence interval [CI], -0.48 to 0.50) and a precision of 0.25. The optimal threshold was 1.4 to predict severe coagulopathy (sensitivity 81% [95% CI, 68%-94%], negative predictive value 98% [95% CI, 97%-99%]), and 1.2 for moderate coagulopathy (sensitivity 80% [95% CI, 72%-88%], negative predictive value 94% [95% CI, 91%-96%]). A low PTr-CGK in the presence of severity criteria (Injury Severity Score ≥ 16, Trauma Associated Severe Hemorrhage score ≥ 12, hemoglobin level < 7 g/dL, fibrinogen level < 2 g/L, base deficit ≥ 6 mmol/L) was strongly associated with a false-negative risk. CONCLUSIONS: The PT point-of-care device is reliable and accurate for the early identification of coagulopathic trauma patients.

Influence of late fluid management on the outcomes of severe trauma patients: A retrospective analysis of 294 severely-injured patients.

BACKGROUND: Liberal late fluid management (LFM) is associated with higher morbi-mortality in critically ill populations. The aim of the study was to assess the association between LFM and duration of mechanical ventilation in a severe trauma population. METHODS: A retrospective analysis of consecutive patients with an ISS≥16 and a length of stay in the intensive care unit (ICU)≥7 days was performed. The conservative LFM group included patients with at least 2 consecutive days with a negative fluid balance between day 3 and day 7; other patients were allocated to the liberal LFM group. RESULTS: 294 severely injured patients were included, 157 (53%) as conservative LFM and 137 (47%) as liberal LFM. The groups did not differ significantly in terms of baseline characteristics, severe injuries, severity criteria or transfusion needs. Liberal LFM was significantly associated with more ventilation days (11 vs 8.5days; P=0.02), less ventilator-free days at day 30 (19 vs 21days; P=0.03), longer ICU stay (19 vs 16days; P=0.03) and longer hospital stay (30 vs 25days; P=0.04). Mortality rates were comparable between groups (6%). Liberal LFM was significantly associated in multivariable analysis with a reduced number of ventilator-free days at day 30 (ß=-2.14 [95% CI, -4.2 to -0.08], P=0.042). CONCLUSIONS: Liberal LFM was associated with higher morbidity in severe trauma patients, longer duration of ventilation, and longer ICU and hospital stays. These results were observed despite similar severity on admission and early fluid management.

Relationship between Obesity and Massive Transfusion Needs in Trauma Patients, and Validation of TASH Score in Obese Population: A Retrospective Study on 910 Trauma Patients.

BACKGROUND: Prediction of massive transfusion (MT) is challenging in management of trauma patients. However, MT and its prediction were poorly studied in obese patients. The main objective was to assess the relationship between obesity and MT needs in trauma patients. The secondary objectives were to validate the Trauma Associated Severe Hemorrhage (TASH) score in predicting MT in obese patients and to use a grey zone approach to optimize its ability to predict MT. METHODS AND FINDINGS: An observational retrospective study was conducted in a Level I Regional Trauma Center Trauma in obese and non-obese patients. MT was defined as ≥10 U of packed red blood cells in the first 24h and obesity as a BMI≥30 kg/m². Between January 2008 and December 2012, 119 obese and 791 non-obese trauma patients were included. The rate of MT was 10% (94/910) in the whole population. The MT rate tended to be higher in obese patients than in non-obese patients: 15% (18/119, 95%CI 9‒23%) versus 10% (76/791, 95%CI 8‒12%), OR, 1.68 [95%CI 0.97‒2.92], p = 0.07. After adjusting for Injury Severity Score (ISS), obesity was significantly associated with MT rate (OR, 1.79[95%CI 1.00‒3.21], p = 0.049). The TASH score was higher in the obese group than in the non-obese group: 7(4-11) versus 5(2-10) (p<0.001). The area under the ROC curves of the TASH score in predicting MT was very high and comparable between the obese and non-obese groups: 0.93 (95%CI, 0.89‒0.98) and 0.94 (95%CI, 0.92‒0.96), respectively (p = 0.80). The grey zone ranged respectively from 10 to 13 and from 9 to 12 in obese and non obese patients, and allowed separating patients at low, intermediate or high risk of MT using the TASH score. CONCLUSIONS: Obesity was associated with a higher rate of MT in trauma patients. The predictive performance of the TASH score and the grey zones were robust and comparable between obese and non-obese patients.

Assessment of Modification of Diet in Renal Disease Equation to Predict Reference Serum Creatinine Value in Severe Trauma Patients: Lessons From an Observational Study of 775 Cases.

OBJECTIVE: We assessed the Modification of Diet in Renal Disease (MDRD) performance to predict serum creatinine (SCr) in severe trauma population and determined the best theoretical glomerular filtration rate (GFR) to use in this estimation. BACKGROUND: Baseline SCr may be misestimated in severe trauma patients because of their specific demographic characteristics including renal hyperfiltration. However, the back-calculated MDRD equation is supposed to estimate SCr using a predetermined GFR of 75 mL/min/1.73 m. METHODS: All severe trauma patients with a normal SCr were retrospectively included between January 2005 and January 2011. For each patient, the lowest SCr (oSCr) observed during the first week was used to estimate the GFR. The median GFR in period 1 (2005-2006) was determined. The back-calculated MDRD performance was assessed in period 2 (2007-2011) to predict oSCr by agreement, precision, and accuracy using a GFR of 75 mL/min/1.73 m (eSCr75-MDRD) or the median GFR observed in period 1 (eSCrTRAUMA-MDRD). RESULTS: A total of 775 patients were studied: mean age, 37.7 ±â€Š17 years; mean Injury Severity Score, 19 ±â€Š11; 75% of male. In period 1 (n = 243), median GFR was 121 mL/min/1.73 m. In period 2 (n = 532), eSCrTRAUMA-MDRD demonstrated better agreement in predicting oSCr than eSCr75-MDRD (mean bias 2 vs 35 µmol/L; P < 0.001). Both precision (14 vs 39 µmol/L, respectively) and accuracy were significantly improved with eSCrTRAUMA-MDRD. Proportion of estimated SCr values that deviated less than 15%, 30%, or 50% was also higher with eSCrTRAUMA-MDRD (P < 0.001). CONCLUSIONS: The eSCr75-MDRD equation systematically overestimates oSCr of severe trauma patients. The eSCrTRAUMA-MDRD equation determined was statistically superior allowing more accurate qualification of acute kidney injury.

Early coagulopathy at hospital admission predicts initial or delayed fibrinogen deficit in severe trauma patients.

BACKGROUND: Early detection of a fibrinogen deficit in the initial phase of trauma is a determinant for anticipating massive blood loss. Hemostatic impairment should rationally be associated with an overall depletion of clotting factors, leading to early coagulopathy. The main objective of this study was to evaluate whether the severity of coagulopathy at admission could predict an initial and delayed fibrinogen deficit during the initial management of severe trauma patients. METHODS: All severe trauma patients admitted consecutively to our trauma center between January 2006 and December 2009 were retrospectively reviewed. The results of coagulation tests and plasma fibrinogen levels at admission were studied. Patients were grouped according to severity of coagulopathy at admission: prothrombin time ratio and/or activated partial thromboplastin time ratio of 1.50 or greater, between 1.49 and 1.20, or less than 1.20. Correlation between severity of coagulopathy at admission and initial or delayed fibrinogen deficit (fibrinogen level < 1.5 g/L) within the first 24 hours was established. RESULTS: Of the 663 patients studied, 481 (72%) were male, and the mean (SD) Injury Severity Score (ISS) was 21.3 (17.6). At admission, 105 patients (20%) had severe coagulopathy, 215 (33%) had moderate coagulopathy, and 313 (47%) had no coagulopathy. The number of patients with a fibrinogen level less than 1.5 g/L at admission increased with the severity of coagulopathy: 87%, 29%, and 1%, respectively (p < 0.001). Corresponding rates for an initial fibrinogen level less than 1.0 g/L were 53%, 2%, 0.3%, respectively (p < 0.001). Moreover, severity of coagulopathy at admission was an independent risk factor of the occurrence of fibrinogen deficit within the first 24 hours (p < 0.001). CONCLUSION: Early coagulopathy at admission in severe trauma patients was strongly associated with a fibrinogen deficit during initial management. In the absence of specific monitoring of fibrinogen, coagulopathy severity helps to guide fibrinogen replacement therapy. LEVEL OF EVIDENCE: Prognostic and epidemiologic study, level III.

Intermittent general anesthesia with controlled ventilation for asleep-awake-asleep brain surgery: a prospective series of 140 gliomas in eloquent areas.

BACKGROUND: Awake brain tumor surgery is a unique opportunity for mapping sensorimotor and cognitive functions, allowing the operator to optimize the resection while preserving the patient's quality of life. During this type of procedure, active participation of the patient is necessary. OBJECTIVE: To assess the efficacy and safety of a method of intermittent general anesthesia with controlled ventilation for performing invasive cerebral mapping. METHODS: We report our prospective and observational single-center study with an asleep-awake-asleep protocol. Aspects of feasibility, airway management, timing of each phase, and occurrence of adverse events were detailed. RESULTS: During a 35-month period, 140 patients underwent resection of a glioma in an eloquent area. During the asleep phases, controlled ventilation with a laryngeal mask was always efficient. Orotracheal intubation was performed for some patients for the second asleep period. The patients remained fully awake for a mean time of 98 minutes. Postural discomfort was reported in 17.8% of cases. There was 1 case of aspiration of gastric contents with a favorable outcome and no mortality. CONCLUSION: Intermittent general anesthesia with controlled ventilation for this type of neurosurgical procedure remains an anesthesiological challenge. However, the results of this study suggest that it may be feasible, reproducible, and relatively safe in the context of a standardized protocol involving members of both anesthesiology and surgery teams. Such a technique has a great potential to improve the surgical results, from both oncological and functional perspectives.