Routine use of Staphylococcus aureus rapid diagnostic test in patients with suspected ventilator-associated pneumonia.

INTRODUCTION: In patients with ventilator-associated pneumonia (VAP), administration of an appropriate empirical antimicrobial treatment is associated with improved outcomes, leading to the prescription of broad-spectrum antibiotics, including a drug active against methicillin resistant Staphylococcus aureus (MRSA). In order to avoid the overuse of antibiotics, the present study aimed to evaluate the technical characteristics of a rapid diagnostic test (Cepheid Xpert assay) in patients with suspected VAP. METHODS: From June 2011 to June 2012, in patients with suspected VAP, a sample from the bronchialalveolar lavage (BAL) or miniBAL was tested in a point-of-care laboratory for a rapid diagnostic test of methicillin susceptible Staphylococcus aureus (MSSA) and MRSA. Then, the result was compared to the quantitative culture with a threshold at 104 colony-forming units per milliliter for bronchoalveolar lavage and 10³ colony-forming units per milliliter for minibronchoalveolar lavage. The study was performed in three intensive care units at two institutions. RESULTS: Four hundred, twenty-two samples from 328 patients were analyzed. The culture of 6 (1.1%) and 28 (6.5%) samples were positive for MRSA and MSSA. The test was not interpretable in 41 (9.3%) patients. The negative predictive values of the rapid detection test were 99.7% (98.1 to 99.9%) and 99.8% (98.7 to 99.9%) for MSSA and MRSA, respectively. CONCLUSION: The rapid diagnostic test is reliable in excluding the presence of MSSA and MRSA in the samples of patients with suspected VAP. Its utility should be regarded depending on the prevalence of MRSA.

Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury.

INTRODUCTION: Renal resistive index (RI), determined by Doppler ultrasonography, directly reveals and quantifies modifications in renal vascular resistance. The aim of this study was to evaluate if mean arterial pressure (MAP) is determinant of renal RI in septic, critically ill patients suffering or not from acute kidney injury (AKI). METHODS: This prospective observational study included 96 patients. AKI was defined according to RIFLE criteria and transient or persistent AKI according to renal recovery within 3 days. RESULTS: Median renal RIs were 0.72 (0.68-0.75) in patients without AKI and 0.76 (0.72-0.80) in patients with AKI (P = 0.001). RIs were 0.75 (0.72-0.79) in transient AKI and 0.77 (0.70-0.80) in persistent AKI (P = 0.84). RI did not differ in patients given norepinephrine infusion and was not correlated with norepinephrine dose. RI was correlated with MAP (ρ = -0.47; P = 0.002), PaO2/FiO2 ratio (ρ = -0.33; P = 0.04) and age (ρ = 0.35; P = 0.015) only in patients without AKI. CONCLUSIONS: A poor correlation between renal RI and MAP, age, or PaO2/FiO2 ratio was found in septic and critically ill patients without AKI compared to patients with AKI. These findings suggest that determinants of RI are multiple. Renal circulatory response to sepsis estimated by Doppler ultrasonography cannot reliably be predicted simply from changes in systemic hemodynamics. As many factors influence its value, the interest in a single RI measurement at ICU admission to determine optimal MAP remains uncertain.

Oxygen tissue saturation is lower in nonsurvivors than in survivors after early resuscitation of septic shock.

BACKGROUND: Growing evidence suggests that the microvascular dysfunction is the key element of the pathogenesis of septic shock. This study's purpose was to explore whether the outcome of septic shock patients after early resuscitation using early goal-directed therapy is related to their muscle tissue oxygenation. METHODS: Tissue oxygen saturation (Sto2) was monitored in septic shock patients using a tissue spectrometer (InSpectra Model 325; Hutchinson Technology, Hutchinson, MN). For the purpose of this retrospective study, the Sto2 values were collected at the first measurement done after the macrohemodynamic variables (mean arterial pressure, urine output, central venous saturation in oxygen) were optimized. RESULTS: After the hemodynamic variables were corrected, no difference was observed between the nonsurvivors and survivors, with the exception of pulse oximetry saturation (94% [92-97%] vs. 97% [94-99%], P = 0.04). The Sto2 values were significantly lower in the nonsurvivors than in the survivors (73% [68-82%] vs. 84% [81-90%], P = 0.02). No correlations were found between the Sto2 and Spo2 (P = 0.7). CONCLUSIONS: In septic shock patients, tissue oxygen saturation below 78% is associated with increased mortality at day 28. Further investigations are required to determine whether the correction of an impaired level of tissue oxygen saturation may improve the outcome of these patients.

NOREPINEPHRINE: NOT TOO MUCH, TOO LONG.

The study was designed to assess whether high dosages of norepinephrine are associated with increased death rate and to determine the dosage of norepinephrine associated with an intensive care unit (ICU) death rate greater than 90%. We conducted a retrospective, noninterventional, observational study in a single ICU (15 beds) of an academic hospital. From January 2009 to May 2013, data of all patients with a diagnosis of septic shock were extracted from our database. Data were collected at the time of the admission in ICU, at the onset of septic shock, and when the maximal posology of norepinephrine was reached. Mortality was assessed in ICU, in hospital, and at day 90. Among the 324 patients with septic shock, the death rate was 48%. The death rate reached 90% for the quantile of patients receiving more than 1 µg/kg per minute of norepinephrine. In our cohort, four independent factors associated with mortality were identified: age (odds ratio, 1.02 [95% confidence interval, 1.00-1.04]; P = 0.02), thrombocytopenia (odds ratio, 3.8 [95% confidence interval, 1.8-8.5]; P < 0.001), urine output less than 500 mL (odds ratio, 8.7 [95% confidence interval, 3.6-25]; P < 0.001), and dosage of norepinephrine greater than 1 µg/kg per minute (odds ratio, 9.7 [95% confidence interval, 4.5-23]; P < 0.001). However, because of the study's design, unmeasured confounding factors should be taken into account in our findings.