Association between augmented renal clearance and clinical failure of antibiotic treatment in brain-injured patients with ventilator-acquired pneumonia: A preliminary study.

OBJECTIVES: This preliminary study aimed to determine whether augmented renal clearance (ARC) impacts negatively on the clinical outcome in traumatic brain-injured patients (TBI) treated for a first episode of ventilator-acquired pneumonia (VAP). METHODS: During a 5-year period, all TBI patients who had developed VAP were retrospectively reviewed to assess variables associated with clinical failure in multivariate analysis. Clinical failure was defined as an impaired clinical response with a need for escalating antibiotics during treatment and/or within 15 days after the end-of-treatment. Recurrence was considered if at least one of the initial causative bacterial strains was growing at a significant concentration from a second sample. Augmented renal clearance (ARC) was defined by an enhanced creatinine clearance exceeding 130mL/min/1.73m2 calculated from a urinary sample during the first three days of antimicrobial therapy. MAIN RESULTS: During the study period, 223 TBI patients with VAP were included and 59 (26%) presented a clinical failure. Factors statistically associated with clinical failure were GSC≤7 (OR=2.2 [1.1-4.4], P=0.03), early VAP (OR=3.9 [1.9-7.8], P=0.0001), bacteraemia (OR=11 [2.2-54], P=0.003) and antimicrobial therapy≤7 days (OR=3.7 [1.8-7.4], P=0.0003). ARC was statistically associated with recurrent infections with an OR of 4.4 [1.2-16], P=0.03. CONCLUSION: ARC was associated with recurrent infection after a first episode of VAP in TBI patients. The optimal administration and dosing of the antimicrobial agents in this context remain to be determined.

Subclavian central venous catheter-related thrombosis in trauma patients: incidence, risk factors and influence of polyurethane type.

INTRODUCTION: The incidence of deep venous thrombosis (DVT) related to a central venous catheter varies considerably in ICUs depending on the population included. The aim of this study was to determine subclavian central venous catheter (SCVC)-related DVT risk factors in severely traumatized patients with regard to two kinds of polyurethane catheters. METHODS: Critically ill trauma patients needing a SCVC for their usual care were prospectively included in an observational study. Depending on the month of inclusion, patients received one of the two available products in the emergency unit: either an aromatic polyurethane SCVC or an aliphatic polyurethane SCVC. Patients were screened weekly by ultrasound for SCVC-related DVT. Potential risk factors were collected, including history-related, trauma-related and SCVC-related characteristics. RESULTS: A total of 186 patients were included with a median Injury Severity Sore of 30 and a high rate of severe brain injuries (21% of high intracranial pressure). Incidence of SCVC-related DVT was 37% (95% confidence interval: 26 to 40) in patients or 20/1,000 catheter-days. SCVC-related DVT occurred within 8 days in 65% of cases. There was no significant difference in DVT rates between the aromatic polyurethane and aliphatic polyurethane SCVC groups (38% vs. 36%). SCVC-related DVT independent risk factors were age>30 years, intracranial hypertension, massive transfusion (>10 packed red blood cell units), SCVC tip position in the internal jugular or in the innominate vein, and ipsilateral jugular catheter. CONCLUSION: SCVC-related DVT concerned one-third of these severely traumatized patients and was mostly clinically silent. Incidence did not depend on the type of polyurethane but was related to age>30 years, intracranial hypertension or misplacement of the SCVC. Further studies are needed to assess the cost-effectiveness of routine screening in these patients in whom thromboprophylaxis may be hazardous.

Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients.

PURPOSE: Acute kidney injury (AKI) is a dynamic process that evolves from an early reversible condition to an established disease. Value of urine indices in the event of AKI is uncertain in critically ill patients. The aim of this study was to evaluate the performance of fractional excretion of urea (FeU) for differentiating persistent from transient AKI in patients admitted to the intensive care unit. METHODS: This was an observational study. Forty-seven patients with AKI according to the RIFLE classification were included. Transient AKI was defined as AKI resolved within 3 days after inclusion. Persistent AKI was defined as persistent serum creatinine elevation or oliguria. RESULTS: Fractional excretion of urea was lower in case of transient, 33% (25-39), than persistent AKI, 47% (36-61) (P = .001). Areas under the receiver operating characteristic curve for FeU in case of transient AKI were better than those for other urinary indexes, 0.78 (95% confidence interval, 0.63-0.92). Optimal cutoff point according to the receiver operating characteristic curve was 40%. In patients treated with diuretics, FeU was the only predictive index of transient AKI. Fractional excretion of urea gradually increased from days 1 to 7 in transient AKI, whereas plasma creatinine decreased. CONCLUSIONS: Fractional excretion of urea less than 40% was found to be a sensitive and specific index in differentiating transient from persistent AKI in intensive care unit patients especially if diuretics had been administered.

Impact of norepinephrine on the relationship between pleth variability index and pulse pressure variations in ICU adult patients.

INTRODUCTION: Pleth Variability Index (PVI) is an automated and continuous calculation of respiratory variations in the perfusion index. PVI correlates well with respiratory variations in pulse pressure (ΔPP) and is able to predict fluid responsiveness in the operating room. ICU patients may receive vasopressive drugs, which modify vascular tone and could affect PVI assessment. We hypothesized that the correlation between PVI and ΔPP and the ability of PVI to identify patients with ΔPP > 13% is dependent on norepinephrine (NE) use. METHODS: 67 consecutive mechanically ventilated patients in the ICU were prospectively included. Three were excluded. The administration and dosage of NE, heart rate, mean arterial pressure, PVI and ΔPP were measured simultaneously. RESULTS: In all patients, the correlation between PVI and ΔPP was weak (r2 = 0.21; p = 0.001). 23 patients exhibited a ΔPP > 13%. A PVI > 11% was able to identify patients with a ΔPP > 13% with a sensitivity of 70% (95% confidence interval: 47%-87%) and a specificity of 71% (95% confidence interval: 54%-84%). The area under the curve was 0.80 ± 0.06. 35 patients (53%) received norepinephrine (NE(+)). In NE(+) patients, PVI and ΔPP were not correlated (r2 = 0.04, p > 0.05) and a PVI > 10% was able to identify patients with a ΔPP > 13% with a sensitivity of 58% (95% confidence interval: 28%-85%) and a specificity of 61% (95% confidence interval:39%-80%). The area under the ROC (receiver operating characteristics) curve was 0.69 ± 0.01. In contrast, NE(-) patients exhibited a correlation between PVI and ΔPP (r2 = 0.52; p < 0.001) and a PVI > 10% was able to identify patients with a ΔPP > 13% with a sensitivity of 100% (95% confidence interval: 71%-100%) and a specificity of 72% (95% confidence interval: 49%-90%). The area under the ROC curve was 0.93 ± 0.06 for NE(-) patients and was significantly higher than the area under the ROC curve for NE(+) patients (p = 0.02). CONCLUSIONS: Our results suggest that in mechanically ventilated adult patients, NE alters the correlation between PVI and ΔPP and the ability of PVI to predict ΔPP > 13% in ICU patients.

The use of bispectral index to monitor barbiturate coma in severely brain-injured patients with refractory intracranial hypertension.

BACKGROUND: Barbiturate therapy in severely traumatic brain-injured (TBI) patients is usually monitored by an electroencephalogram (EEG) with burst-suppression pattern as a target. The Bispectral Index (BIS) is derived from EEG and considers cortical silence. We sought to determine whether a BIS range could predict a specific burst-suppression pattern. METHODS: Eleven TBI patients treated with barbiturate were included prospectively. EEG was recorded daily for 1 h. Every 5 min, the number of bursts and the suppression ratio (suppression ratio from EEG [SR(EEG)]: percentage of last 60 s in cortical silence) was calculated for 1 min on the raw EEG and compared to concomitant data from the BIS-XP (BIS and suppression ratio [SR(BIS)]). The optimal level of barbiturate coma was defined as 2-5 bursts/min in the EEG. A BIS range predictive of optimal level was determined from all data and its accuracy was studied for each examination. RESULTS: Agreement between SR(EEG) and SR(BIS) was high (interclass correlation coefficient 0.94 [95% confidence interval: 0.90-0.96]). There was a significant association between SR(EEG) and BIS. Significant disagreements were observed in some examinations. The best accuracy to predict optimal pattern was obtained with a BIS range from 6 to 15. CONCLUSION: The relationship between BIS and SR(EEG) was high in TBI patients treated with barbiturates. The rate of barbiturate infusion might be decreased if BIS is <6 or increased if BIS is >15. Correspondence between BIS and suppression pattern should periodically be checked by observation of the EEG analogical signal (as displayed by BIS-XP).

Cardiac output measurement in patients undergoing liver transplantation: pulmonary artery catheter versus uncalibrated arterial pressure waveform analysis.

BACKGROUND: Cardiac output (CO) and invasive hemodynamic measurements are useful during liver transplantation. The pulmonary artery catheter (PAC) is commonly used for these patients, despite the potential complications. Recently, a less invasive device (Vigileo/FloTrac) became available, which estimates CO using arterial pressure waveform analysis without external calibration. In this study, we compared CO obtained with a PAC using automatic thermodilution, instantaneous CO stat-mode (ICO(SM)), and CO obtained with the new device, arterial pressure waveform analysis (APCO) in patients undergoing liver transplantation. METHODS: Twenty sets of simultaneous measurements of APCO and ICO(SM) were determined in sedated and mechanically ventilated patients undergoing liver transplantation. Time points were as follows: after PAC insertion (T1-3), after portal clamping (T4-6), during anhepathy (T7-9), after graft reperfusion (T10-15), and in the postoperative period in the intensive care unit (T15-20). RESULTS: We enrolled 20 patients and 400 measurements were obtained. No data were rejected. Bias between ICO(SM) and APCO was 0.8 L/min, 95% limits of agreement were -1.8 to 3.5 L/min. The percentage error was 43%. Bias between ICO(SM) and APCO was correlated with systemic vascular resistance [r(2) = 0.55, P < 0.0001, y = 15.8-2.2 ln(x)] and subgroup analysis revealed an increase in the bias and in the percentage error in patients with low systemic vascular resistance (Child-Pugh grade B and C patients). There was no difference between the different surgical periods. CONCLUSIONS: Our results suggest that Vigileo/FloTrac CO monitoring data do not agree well with those of automatic thermodilution in patients undergoing liver transplantation, especially in Child-Pugh grade B and C patients with low systemic vascular resistance.

Generation of procoagulant microparticles in cerebrospinal fluid and peripheral blood after traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) can induce cell damage. Procoagulant microparticles (MPs) are reliable markers of cell stimulation. The aim of this study was to investigate the generation of procoagulant MPs in the cerebrospinal fluid (CSF) and plasma of patients with severe TBI. MATERIAL: CSF and plasma MPs of 16 patients with severe TBI were quantified by functional prothrombinase assay (i) on the day of the trauma, (ii) during a 10-day follow-up and compared with control samples. The cellular origin of MP was determined after capture with specific antibodies. RESULTS: The CSF and plasma of patients with severe TBI revealed a significantly increased generation of MP compared with control samples on the day of the trauma (CSF: 4.5 +/- 1.8 vs. 0.83 +/- 0.28 nanomolar PhtdSer equivalent; p = 0.01 and plasma 4.1 +/- 3.7 vs. 2.3 +/- 0.19 nanomolar PhtdSer equivalent; p = 0.02). Procoagulant MPs were mainly of platelet and endothelial origin in CSF. MPs decreased significantly in the CSF 10 days after TBI. In CSF, a sustained generation of procoagulant MP was evidenced in two patients presenting a poor clinical outcome. In the blood flow, elevated amounts of procoagulant MPs were detected in three patients presenting disseminated intravascular coagulopathy during the follow-up. CONCLUSION: Procoagulant MP testifying to platelet and endothelial activation are produced in the CSF and in the plasma after severe TBI. A sustained generation of procoagulant MP in the CSF could contribute to a poor clinical outcome.

How is norepinephrine used in intensive care? A field study.

OBJECTIVE: To assess how norepinephrine (NE), an emergency treatment of cardiovascular collapse, is used in intensive care. METHODS: Nurses and physicians of 14 intensive care units of the Bordeaux University Hospital were given questionnaires on the way they say they use NE and on actual NE treatment of patients. RESULTS: The clinical monitoring parameters cited were blood pressure, heart rate and hourly urine flow. Only 25% of the prescribers indicated the systematic use of hemodynamic monitoring. All the prescribers indicated they adapted the treatment to clinical objectives and blood pressure, and 77.5% to hourly urine flow. Initial NE concentrations ranged from 0.5 to 2 mg/ml, diluted in saline or dextrose. Initial prescribed dose ranged from 0.1 to 1 microg/kg/min. Large differences were observed between services and even within units. CONCLUSION: These data clearly show the need for recommendations regarding the use of norepinephrine.

Prevention of intravascular catheter-related infection with newer chlorhexidine-silver sulfadiazine-coated catheters: a randomized controlled trial.

BACKGROUND: The indication of antiseptic-coated catheters remains debated. OBJECTIVE: To test the ability of the new generation of chlorhexidine-silver and sulfadiazine-coated catheters, with enhanced antiseptic coating, to reduce the risk of central venous catheter (CVC)-related infection in ICU patients. DESIGN: Multicentre randomized double-blind trial. PATIENTS AND SETTING: A total of 397 patients from 14 ICUs of university hospitals in France. INTERVENTION: Patients were randomized to receive an antiseptic-coated catheter (ACC) or a standard non-coated catheter (NCC). MEASUREMENTS: Incidence of CVC-related infection. RESULTS: Of 367 patients having a successful catheter insertion, 363 were analysed (175 NCC and 188 ACC). Patients had one (NCC=162, ACC=180) or more (NCC=13, ACC=11) CVC inserted. The two groups were similar for insertion site [subclavian (64 vs 69)] or jugular (36 vs 31%)], and type of catheters (single-lumen 18 vs 18%; double-lumen 82 vs 82%), and mean (median) duration of catheterisation [12.0+/-11.7 (9) vs 10.5+/-8.8 (8) days in the NCC and ACC groups, respectively]. Significant colonisation of the catheter occurred in 23 (13.1%) and 7 (3.7%) patients, respectively, in the NCC and ACC groups (11 vs 3.6 per 1000 catheter-days; p=0.01); CVC-related infection (bloodstream infection) occurred in 10 (5) and 4 (3) patients in the NCC and CC groups, respectively (5.2 vs 2 per 1000 catheter days; p=0.10). CONCLUSIONS: In the context of a low baseline infection rate, ACC were associated with a significant reduction of catheter colonisation and a trend to reduction of infection episodes, but not of bloodstream infection.