Can we predict septic shock in patients with hospital-acquired pneumonia?

Hospital-acquired pneumonia is a serious and potentially life-threatening complication, with reported pneumonia-attributable mortality rates as high as 50%. Rapid diagnosis and immediate institution of adequate empirical antimicrobial treatment are of paramount importance in patient management. Nevertheless, some patients deteriorate and develop respiratory insufficiency, septic shock and a multiorgan dysfunction syndrome. Early recognition of these patients might help in reducing morbidity and mortality. Elevated systemic levels of proinflammatory cytokines (IL-1β, IL-6, IL-8 and IL-10) at the time of diagnosis of hospital-acquired pneumonia appear to be indicative of subsequent progression to septic shock. Should this now become a part of patient management?     

Can peripheral venous pressure be interchangeable with central venous pressure in patients undergoing cardiac surgery?

Objective Pressure measurements at the level of the right atrium are commonly used in clinical anesthesia and the intensive care unit (ICU). There is growing interest in the use of peripheral venous sites for estimating central venous pressure (CVP). This study compared bias, precision, and covariance in simultaneous measurements of CVP and of peripheral venous pressure (PVP) in patients with various hemodynamic conditions.Design and setting Operating room and ICU of a tertiary care university-affiliated hospital.Patients Nineteen elective cardiac surgery patients requiring cardiopulmonary bypass were studied.Interventions A PVP catheter was placed in the antecubital vein and connected to the transducer of the pulmonary artery catheter with a T connector. Data were acquired at different times during cardiac surgery and in the ICU.Measurements and results A total of 188 measurements in 19 patients were obtained under various hemodynamic conditions which included before and after the introduction of mechanical ventilation, following the induction of anesthesia, fluid infusion, application of positive end expiratory pressure and administration of nitroglycerin. PVP and CVP values were correlated and were interchangeable, with a bias of the PVP between –0.72 and 0 mmHg compared to the CVP.Conclusions PVP monitoring can accurately estimate CVP under various conditions encountered in the operating room and in the ICU.This study was supported by the Plan de Pratique des Anesthésiologistes of the Montreal Heart Institute and the Fonds de la Recherche en Santé du Québec.     

Can venous-to-arterial carbon dioxide differences reflect microcirculatory alterations in patients with septic shock?

Purpose

Septic shock has been associated with microvascular alterations and these in turn with the development of organ dysfunction. Despite advances in video microscopic techniques, evaluation of microcirculation at the bedside is still limited. Venous-to-arterial carbon dioxide difference (Pv-aCO₂) may be increased even when venous O₂ saturation (SvO₂) and cardiac output look normal, which could suggests microvascular derangements. We sought to evaluate whether Pv-aCO₂ can reflect the adequacy of microvascular perfusion during the early stages of resuscitation of septic shock.

Methods

Prospective observational study including 75 patients with septic shock in a 60-bed mixed ICU. Arterial and mixed-venous blood gases and hemodynamic variables were obtained at catheter insertion (T0) and 6 h after (T6). Using a sidestream dark-field device, we simultaneously acquired sublingual microcirculatory images for blinded semiquantitative analysis. Pv-aCO₂ was defined as the difference between mixed-venous and arterial CO₂ partial pressures.

Results

Progressively lower percentages of small perfused vessels (PPV), lower functional capillary density, and higher heterogeneity of microvascular blood flow were observed at higher Pv-aCO₂ values at both T0 and T6. Pv-aCO₂ was significantly correlated to PPV (T0: coefficient ?5.35, 95 % CI ?6.41 to ?4.29, p < 0.001; T6: coefficient, ?3.49, 95 % CI ?4.43 to ?2.55, p < 0.001) and changes in Pv-aCO₂ between T0 and T6 were significantly related to changes in PPV (R ² = 0.42, p < 0.001). Absolute values and changes in Pv-aCO₂ were not related to global hemodynamic variables. Good agreement between venous-to-arterial CO₂ and PPV was maintained even after corrections for the Haldane effect.

Conclusions

During early phases of resuscitation of septic shock, Pv-aCO₂ could reflect the adequacy of microvascular blood flow.

     

Can MR elastography be used to measure liver stiffness in patients with iron overload?

Untreated hepatic iron overload causes hepatic fibrosis and cirrhosis and can predispose to hepatocellular carcinoma. MR elastography (MRE) provides a non-invasive means to measure liver stiffness, which correlates with liver fibrosis but standard gradient recalled echo (GRE)-based MRE techniques fail in patients with high iron due to very low hepatic signal. Short echo time (TE) 2D spin echo echoplanar imaging (SE-EPI)-based MRE may allow measurement of stiffness in the iron loaded liver. The purpose of this study was to describe the use of such an MRE sequence in patients undergoing liver iron quantification by MRI. In our preliminary study of 43 patients with mean LIC of 9.3 mg/g (range 1.8–21.5 mg/g), liver stiffness measurements could be made in 77% (33/43) of patients with a short TE, SE-EPI based MRE sequence. On average, mean LIC in patients with failed MRE was higher than in those with successful MRE (15.9 mg/g dry weight vs. 7.3 mg/g), but a cut-off value for successful MRE could not be established. Seven patients (21% of those with successful MRE) had liver stiffness values suggestive of the presence of significant fibrosis (> 2.49 kPa). A short TE, SE-EPI based MR elastography sequence allows successful measurement of liver stiffness in a majority of patients with liver iron loading, potentially allowing non-invasive screening for fibrosis.

     

Can passive leg raising be used to guide fluid administration?

Predicting fluid responsiveness has become a topic of major interest. Measurements of intravascular pressures and volumes often fail to predict the response to fluids, even though very low values are usually associated with a positive response to fluids. Dynamic indices reflecting respiratory-induced variations in stroke volume have been developed; however, these cannot be used in patients with arrhythmia or with spontaneous respiratory movements. The passive leg raising (PLR) test has been suggested to predict fluid responsiveness. PLR induces an abrupt increase in preload due to autotransfusion of blood contained in capacitance veins of the legs, which leads to an increase in cardiac output in preload-dependent patients. This commentary discusses some of the technical issues related to this test.     

Should heparin-binding protein levels be routinely monitored in patients with severe sepsis and septic shock?

ABSTRACT: Heparin-binding protein (HBP), also known as azurocidin, has multiple functions in the inflammatory process, especially during severe infections. Beside its antimicrobial properties, HBP may induce vascular leakage leading to extravascular efflux, which is an important pathophysiologic event in the development of septic shock. Not surprisingly, high HBP plasma levels are found in severe sepsis patients and in septic shock patients as well as in serious infections associated with endothelial damage. In the present issue of Critical Care, Linder and colleagues demonstrate new aspects of HBP daily monitoring in ICU patients. The authors observed that high HBP plasma levels are associated with an increased mortality rate in both septic and nonseptic critically ill patients, indicating that HBP may be a reliable prognostic biomarker. However, there are some limitations hindering rapid translation of these interesting findings into the daily routine. First, the group of nonseptic critically ill patients (n = 28) enrolled in the study was rather small as compared with the septic group (n = 151). Moreover, 50% of nonseptic patients developed infection while hospitalized in the ICU, and to classify them as truly nonseptic patients is problematic. Second, there is a lack of a routine diagnostic method for HBP analysis. Nevertheless, if the results of the present study are validated in large clinical trials in different ICU populations and cost-effectiveness data become available, the serial HBP measurements will have a promising future.     

How much fluid resuscitation is optimal in septic shock?

ABSTRACT: Smith and Perner report an observational cohort study of 164 patients with septic shock. For patients still alive on day 3, higher compared with lower fluid volume resuscitation was associated with lower 90-day mortality. This association of a relationship between fluid intake and decreased mortality aligns with the randomized controlled trial of early goal-directed therapy and later observational studies. I suggest careful individualization of fluid resuscitation to achieve adequate mean arterial pressure (about 60 to 70 mmHg) and normalization of arterial lactate levels in septic shock. TRIAL REGISTRATION: ISRCTN94845869.     

Can the Hospital Anxiety and Depression Scale be used in patients with schizophrenia?

Rationale, aims, objectives The Hospital Anxiety and Depression Scale (HADS) was developed explicitly for use in non‐psychotic populations, yet is routinely used for screening patients with psychotic illness. The utility of the HADS as a screening instrument for use in patients with schizophrenia was investigated. Method Exploratory factor analysis and confirmatory factor analysis were conducted on the HADS to determine its psychometric properties in 100 patients with a primary ICD‐10 diagnosis of schizophrenia. Results Three distinct factors were identified within the HADS. Support was found for the clinical use of the HADS anxiety subscale to assess anxiety in patients with schizophrenia; however, evidence was also found that the HADS depression subscale may not be a unidimensional measure of depression in this clinical group. Conclusions Caution should be used when using the HADS depression subscale in this clinical group. The direction of future research in this area is indicated, in particular comparison of HADS anxiety and depression measures to determine further the validity or otherwise of these subscale domains.     

Is compartment pressure related to plasma colloid osmotic pressure, in patients during and after cardiac surgery?

Haemodilution is always considerable during cardiopulmonary bypass (CPB). If this extra fluid sits in the muscle compartments then a corresponding rise in the compartment pressure (CP) is to be expected. The aim of this study was to measure pressure changes in a body compartment with new equipment, the MTC (Microtransducer). Changes in plasma colloid osmotic pressure (COP) were also measured during and after CPB to find a connection, if any, between CP and plasma COP. Ten elective consecutive CPB patients were studied. A 3-French (3-F) catheter-size electronic MTC was inserted in an anterior tibial compartment before CPB. The CP was monitored for 48 h. Plasma COP was also measured before, during and after CPB. CP increased significantly during and after CPB in all patients (p=0.01). COP decreased significantly in all patients (p=0.005), but no correlation was found between changes in COP and CP values in this study. Most of the patients reached their highest CP just after weaning off bypass. The CP remained elevated for 48 h, even though it then tended to decrease again. None of the patients reached the starting value within 48 h. COP decreased rapidly after going on bypass, but returned towards its starting value approximately 6 h after bypass. It is concluded that CP increases considerably during and after CPB and stays increased for at least 2 days after CPB. COP decreases during CPB, but reaches normal values 6 h after the CPB. No correlation was found between changes in CP and COP The MTC is a safe and easy way to measure intracompartment pressure.     

Can yeast isolation in peritoneal fluid be predicted in intensive care unit patients with peritonitis?

OBJECTIVE: To generate and validate a predictive score of yeast isolation based on independent risk factors of yeast isolation in intensive care unit patients with peritonitis. DESIGN: Retrospective cohort study to determine independent risk factors of yeast isolation, generation of the score, and validation in a prospective cohort of patients with peritonitis. SETTING: Tertiary-care, university-affiliated hospital. PATIENTS: Two hundred twenty-one patients with peritonitis hospitalized in a surgical intensive care unit between 1994 and 1999 for the retrospective cohort and 57 patients in the prospective cohort (2000). MEASUREMENTS AND MAIN RESULTS: Four independent risk factors of yeast isolation in peritoneal fluid (similar odds ratio) were found in the retrospective cohort: female gender, upper gastrointestinal tract origin of peritonitis, intraoperative cardiovascular failure, and previous antimicrobial therapy at least 48 hrs before the onset of peritonitis. A score based on the number of risk factors was constructed (grade A = zero or one risk factor, grade B = at least two risk factors, grade C = at least three risk factors, and grade D = four risk factors), and validated in the prospective cohort. For a grade C score, sensitivity was 84%, specificity was 50%, positive and negative predictive values were 67% and 72%, respectively, and overall accuracy was 71%. CONCLUSIONS: Four independent risk factors of yeast isolation in the peritoneal fluid were identified in critically ill surgical patients with peritonitis. The presence of at least three of these factors (grade C score) was associated with a high rate of yeast detection. This approach could be helpful to initiate early antifungal therapy in this patient population.