IntroductionWe have almost no information concerning the value of inferior vena cava (IVC) respiratory variations in spontaneously breathing ICU patients (SBP) to predict fluid responsiveness.MethodsSBP with clinical fluid need were included prospectively in the study. Echocardiography and Doppler ultrasound were used to record the aortic velocity-time integral (VTI), stroke volume (SV), cardiac output (CO) and IVC collapsibility index (cIVC) ((maximum diameter (IVCmax)– minimum diameter (IVCmin))/ IVCmax) at baseline, after a passive leg-raising maneuver (PLR) and after 500 ml of saline infusion.ResultsFifty-nine patients (30 males and 29 females; 57 ± 18 years-old) were included in the study. Of these, 29 (49 %) were considered to be responders (≥10 % increase in CO after fluid infusion). There were no significant differences between responders and nonresponders at baseline, except for a higher aortic VTI in nonresponders (16 cm vs. 19 cm, p = 0.03). Responders had a lower baseline IVCmin than nonresponders (11 ± 5 mm vs. 14 ± 5 mm, p = 0.04) and more marked IVC variations (cIVC: 35 ± 16 vs. 27 ± 10 %, p = 0.04). Prediction of fluid-responsiveness using cIVC and IVCmax was low (area under the curve for cIVC at baseline 0.62 ± 0.07; 95 %, CI 0.49-0.74 and for IVCmax at baseline 0.62 ± 0.07; 95 % CI 0.49-0.75). In contrast, IVC respiratory variations >42 % in SBP demonstrated a high specificity (97 %) and a positive predictive value (90 %) to predict an increase in CO after fluid infusion.ConclusionsIn SBP with suspected hypovolemia, vena cava size and respiratory variability do not predict fluid responsiveness. In contrast, a cIVC >42 % may predict an increase in CO after fluid infusion.

A very low percentage of patients satisfied all criteria for valid use of ΔPP in the evaluation of fluid responsiveness. Physicians must consider limitations to the validity of ΔPP before using this variable.

A Cedecea davisae isolate, which was intermediate or resistant to third-generation cephalosporins and carbapenems, was recovered from a urine sample. Susceptibility testing, isoelectric focusing, and analysis of outer membrane proteins showed that AmpC ␤-lactamase expression combined with porin deficiency accounted for the carbapenem resistance. A cloning experiment followed by phenotypic and enzymatic characterization identified a novel class C enzyme that was phylogenetically and biochemically close to the chromosome-borne ␤-lactamases of the genera Enterobacter and Citrobacter. C edecea davisae is an enterobacterium that can be responsible for human infections (1-4). Cephalothin resistance has been already reported in this species, but the mechanism has not been yet elucidated (5).The aim of this work was to identify the mechanisms of resistance of a C. davisae clinical isolate that was resistant to almost all ␤-lactams. It was recovered from a 77-year-old woman who was hospitalized in an intensive care unit of the teaching hospital of Amiens. Eighteen days after a cardiac valve replacement, the patient had a hemorrhagic shock due to retroperitoneal bleeding. The urine sample recovered after nephrostomy was sent to the Laboratory of Bacteriology. It grew a Gram-negative rod (10 7 CFU/ml) that was identified as C. davisae FUR by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (Shimadzu, Marne la Vallée, France) and 16S rRNA sequencing. The patient was started successfully on intravenous ciprofloxacin for 7 days.