Claudia Brusasco

Ultrasound localization of central vein catheter and detection of postprocedural pneumothorax: An alternative to chest radiography

Objective: To determine the usefulness of ultrasound to evaluate central venous catheter misplacements and detection of pneumothorax, thus obviating postprocedural radiograph. After the insertion of a central venous catheter, chest radiograph is usually obtained to ensure correct positioning of the catheter tip and detect postprocedural complications. Design: Prospective observational study. Setting: Adult intensive care unit. Patients: 111 consecutive patients undergoing central venous catheter positioning, using a landmark technique and contrast-enhanced ultrasonography. Measurements and Main Results: A postprocedural chest radiograph was obtained for all patients and was considered as a reference technique. At the end of the procedure, a B-mode ultrasonography was first performed to assess catheter position and detect pneumothorax. Right atrium positioning was detected in 19 patients by ultrasonography, and an additional six by contrast enhanced ultrasonography. Combining ultrasonography and contrast enhanced ultrasonography yielded a 96% sensitivity and 93% specificity in detecting catheter misplacement. Concordance was 95% and &kgr; value was 0.88 (p < .001). Pneumothorax was detected in four patients by ultrasonography and in two by chest radiograph (concordance = 98%). The mean time required to perform ultrasonography plus contrast enhanced ultrasonography was 10 ± 5 mins vs. 83 ± 79 mins for chest radiograph (p < .05). Conclusions: The close concordance between ultrasonography plus contrast enhanced ultrasonography and chest radiograph justifies the use of sonography as a standard technique to ensure the correct positioning of the catheter tip and to detect pneumothorax after central venous catheter cannulation to optimize use of hospital resources and minimize time consumption and radiation. Chest radiograph will be necessary when sonographic examination is impossible to perform by technical limitations.

Hemorrhagic Shock in Polytrauma Patients: Early Detection with Renal Doppler Resistive Index Measurements

PURPOSE To investigate whether renal Doppler resistive index (RI) changes occur early during posttraumatic bleeding and may be predictive of occult hypoperfusion-and thus hemorrhagic shock-in patients with polytrauma. MATERIALS AND METHODS This study was approved by the institutional ethics committee, and informed consent was obtained from all patients. The renal Doppler RI was measured in 52 hemodynamically stable adult patients admitted to the emergency department (ED) because of polytrauma. Renal Doppler RI, hemoglobin, standard base excess, lactate, systolic blood pressure, pH, heart rate, and inferior vena cava diameter values were recorded at admittance and correlated with outcome (progression or nonprogression to hemorrhagic shock). Logistic regression analysis was performed to assess the risk factors for progression to hemorrhagic shock. RESULTS Twenty-nine patients developed hemorrhagic shock, and 23 did not. At univariable analysis, the hemorrhagic shock group, as compared with the nonhemorrhagic shock group, had higher renal Doppler RI (mean, 0.80 ± 0.10 [standard deviation] vs 0.63 ± 0.03; P < .01), injury severity score (mean, 36 ± 11 vs 26 ± 5; P < .01), and standard base excess (mean, -4.0 mEq/L ± 4 vs 1 mEq/L ± 3; P = .04) values. At logistic regression analysis, a renal Doppler RI greater than 0.7 (vs less than or equal to 0.7) was the only independent risk factor for progression to hemorrhagic shock (odds ratio, 57.8; 95% confidence interval: 10.5, 317.0) (P < .001). CONCLUSION In polytrauma patients who are hemodynamically stable at admittance to the ED, renal cortical blood flow redistribution occurs very early in response to occult bleeding and might be noninvasively detected by using the renal Doppler RI. A renal Doppler RI greater than 0.7 is predictive of progression to hemorrhagic shock in polytrauma patients.

Assessment of extravascular lung water by quantitative ultrasound and CT in isolated bovine lung

Lung ultrasonography (LUS) and computed tomography (CT) were compared for quantitative assessment of extravascular lung water (EVLW) in 10 isolated bovine lung lobes. LUS and CT were obtained at different inflation pressures before and after instillation with known amounts of hypotonic saline. A video-based quantitative LUS analysis was superior to both single-frame quantitative analysis and visual scoring in the assessment of EVLW. Video-based mean LUS intensity was strongly correlated with EVLW density (r(2)=0.87) but weakly correlated with mean CT attenuation (r(2)=0.49) and physical density (r(2)=0.49). Mean CT attenuation was weakly correlated with EVLW density (r(2)=0.62) but strongly correlated with physical density (r(2)=0.99). When the effect of physical density was removed by partial correlation analysis, EVLW density was significantly correlated with video-based LUS intensity (r(2)=0.75) but not mean CT attenuation (r(2)=0.007). In conclusion, these findings suggest that quantitative LUS by video gray-scale analysis can assess EVLW more reliably than LUS visual scoring or quantitative CT.

Chest ultrasound in acute respiratory distress syndrome.

Purpose of reviewThis review discusses the role of chest ultrasound in diagnosis and management of acute respiratory distress syndrome (ARDS) and the most recent technical progresses in this field. Recent findingsClinically, suspected ARDS can be easily confirmed by lung ultrasonography through the recognition of a typical pattern characterized by B-lines, spared areas, pleural line thickening, and subpleural consolidations. A visual score based on number and thickness of B-lines permits a semiquantitative evaluation of the amount of extravascular lung water and lung density. Recently, a quantitative lung ultrasound method has been proposed. The heart may be also involved in ARDS either primarily or by the application of positive pressure ventilation. The incidence of acute cor pulmonale during ARDS is, even if under protective ventilation, not negligible. The use of echocardiography combined with lung ultrasound is important for early detection of cor pulmonale, identification of the best ventilator strategy to preserve heart-to-lung interaction, and prediction of weaning success. SummaryAn ultrasound-integrated approach combining lung ultrasound and echocardiography should be recommended as a suitable technique to manage ARDS during diagnosis, mechanical ventilation setting, and weaning.

Ultrasound-Guided Central Venous Cannulation in Bariatric Patients

BackgroundCentral venous catheterization may be difficult in morbidly obese patients because anatomic landmarks are often obscured.MethodsWe evaluated the efficacy and safety of ultrasound-guided central venous cannulation in 55 patients undergoing bariatric surgery. The usefulness of ultrasonic examination combined with intraatrial electrocardiogram as a diagnostic tool for catheter misplacement was studied.ResultsPreliminary ultrasound examination of the neck vessels demonstrated anatomical variations in the position of internal jugular vein in 19 cases and four unrecognized asymptomatic thromboses of the right internal jugular vein. Central venous catheterization was successful in all 55 patients, in 51 with single skin puncture, and in 42 with single vein puncture. In three cases in whom the catheter was misplaced, this was detected by bedside ultrasonic examination during the procedure and immediately corrected by real-time echographic visualization. No arterial puncture, no hematoma, and no pneumothorax occurred in any patient. Successful catheter placement was also confirmed in all patients by post-operative chest X-ray. No evidence of infection or thrombosis subsequently was noted.ConclusionsThe use of ultrasound guidance may increase the success rate and decrease the incidence of complications associated with central venous cannulation. The advantages of this approach is visualization of the anatomical structures at puncture site prior to skin puncture and the ability to track needle and guide-wire placement during the procedure. With its high accuracy in detecting catheter misplacement, bedside ultrasonic examination combined with intraatrial electrocardiogram may further decrease morbidity associated with misplaced central venous catheters.

Effects of pentoxifylline on intestinal bacterial overgrowth, bacterial translocation and spontaneous bacterial peritonitis in cirrhotic rats with ascites

BACKGROUND Prophylaxis of spontaneous bacterial peritonitis with norfloxacin has been associated to development of antibiotic resistance. We investigated whether pentoxifylline compared to norfloxacin reduces bacterial translocation and spontaneous bacterial peritonitis in rats with CCl(4)-induced cirrhosis and ascites. METHOD After development of cirrhosis and ascites, animals were randomly allocated to receive pentoxifylline (16 mg/kg/d every 8h, oral route, n=13) or placebo (n=12) for 15 days. An additional group of 8 cirrhotic rats was given norfloxacin (5mg/kg/d for 15 days). Six healthy rats served as controls. Cecal flora and the prevalence of bacterial translocation and spontaneous bacterial peritonitis were analysed. Serum and ascitic fluid levels of TNF-alpha and cecal levels of malondialdehyde were also measured. RESULTS Pentoxifylline in comparison to placebo reduced intestinal bacterial overgrowth (21% vs. 67%, p=0.04), bacterial translocation to cecal lymph nodes (23% vs. 75%, p=0.03) and prevented spontaneous bacterial peritonitis (0% vs. 33%, p=0.04) by Enterobacteriaceae. Norfloxacin administration induced similar results. Pentoxifylline (0.18 ± 0.10 nmol/mg), but not norfloxacin (0.25 ± 0.13; p=0.02), significantly reduced cecal mucosal levels of malondialdehyde compared to placebo (0.33 ± 0.16; p=0.03). CONCLUSION In cirrhotic rats with ascites: (a) pentoxifylline as well as norfloxacin reduced intestinal bacterial overgrowth and bacterial translocation and prevented spontaneous bacterial peritonitis; (b) pentoxifylline, but not norfloxacin, reduced oxidative stress in cecal mucosal.

Quantitative Analysis of Lung Ultrasonography for the Detection of Community-Acquired Pneumonia: A Pilot Study

Background and Objective. Chest X-ray is recommended for routine use in patients with suspected pneumonia, but its use in emergency settings is limited. In this study, the diagnostic performance of a new method for quantitative analysis of lung ultrasonography was compared with bedside chest X-ray and visual lung ultrasonography for detection of community-acquired pneumonia, using thoracic computed tomography as a gold standard. Methods. Thirty-two spontaneously breathing patients with suspected community-acquired pneumonia, undergoing computed tomography examination, were consecutively enrolled. Each hemithorax was evaluated for the presence or absence of abnormalities by chest X-ray and quantitative or visual ultrasonography. Results. Quantitative ultrasonography showed higher sensitivity (93%), specificity (95%), and diagnostic accuracy (94%) than chest X-ray (64%, 80%, and 69%, resp.), visual ultrasonography (68%, 95%, and 77%, resp.), or their combination (77%, 75%, and 77%, resp.). Conclusions. Quantitative lung ultrasonography was considerably more accurate than either chest X-ray or visual ultrasonography in the diagnosis of community-acquired pneumonia and it may represent a useful first-line approach for confirmation of clinical diagnosis in emergency settings.

Splenic Doppler resistive index for early detection of occult hemorrhagic shock after polytrauma in adult patients.

ABSTRACT The objective of this study was to evaluate whether direct assessment of splenic circulation by splenic Doppler resistive index (Doppler RI) is a clinically useful noninvasive method for an early detection of occult hemorrhagic shock after polytrauma in adult patients. Splenic Doppler RI was measured in 49 hemodynamically stable adult patients admitted to the emergency department because of polytrauma. Renal Doppler RI was also determined in 20 patients. Spleen size, Injury Severity Score, systolic blood pressure, heart rate, blood lactate, standard base excess, pH, hemoglobin, and inferior vena cava diameter values were recorded at admission and at 24 h. Patients were grouped according to whether signs of hemorrhagic shock did (n = 22) or did not (n = 27) occur within the first 24 h from admission. Patients who developed hemorrhagic shock had significantly higher splenic and renal Doppler RI, higher Injury Severity Score, and lower standard base excess at admission. By multivariate logistic regression, splenic Doppler RI resulted to be a predictor of hemorrhagic shock development within the first 24 h from admission. Splenic Doppler RI may represent a clinically useful noninvasive method for early detection of occult hemorrhagic shock and persistent occult hypoperfusion after polytrauma in adult patients.

Diagnostic value of chest ultrasound after cardiac surgery: a comparison with chest X-ray and auscultation.

OBJECTIVE Chest auscultation and chest x-ray commonly are used to detect postoperative abnormalities and complications in patients admitted to intensive care after cardiac surgery. The aim of the study was to evaluate whether chest ultrasound represents an effective alternative to bedside chest x-ray to identify early postoperative abnormalities. DESIGN Diagnostic accuracy of chest auscultation and chest ultrasound were compared in identifying individual abnormalities detected by chest x-ray, considered the reference method. SETTING Cardiac surgery intensive care unit. PARTICIPANTS One hundred fifty-one consecutive adult patients undergoing cardiac surgery. INTERVENTIONS All patients included were studied by chest auscultation, ultrasound, and x-ray upon admission to intensive care after cardiac surgery. MEASUREMENTS AND MAIN RESULTS Six lung pathologic changes and endotracheal tube malposition were found. There was a highly significant correlation between abnormalities detected by chest ultrasound and x-ray (k = 0.90), but a poor correlation between chest auscultation and x-ray abnormalities (k = 0.15). CONCLUSIONS Chest auscultation may help identify endotracheal tube misplacement and tension pneumothorax but it may miss most major abnormalities. Chest ultrasound represents a valid alternative to chest x-ray to detect most postoperative abnormalities and misplacements.

Mechanisms for reduced pulmonary diffusing capacity in haematopoietic stem-cell transplantation recipients

Lung diffusing capacity for CO (DLCO) is compromised in haematopoietic stem-cell transplantation (HSCT) recipients. We derived alveolar-capillary membrane conductance (DM,CO) and pulmonary capillary volume (VC) from DLCO and diffusing capacity for NO (DLNO). Forty patients were studied before and 6 weeks after HSCT. Before HSCT, DLNO and DLCO were significantly lower than in 30 healthy controls. DM,CO was ∼40% lower in patients than in controls (p<0.001), whereas VC did not differ significantly. After HSCT, DLNO and DM,CO further decreased, the latter by ∼22% from before HSCT (p<0.01) while VC did not change significantly. Lung density, serum CRP and reactive oxygen metabolites were significantly increased, with the latter being correlated (R2=0.71, p<0.001) with the decrement in DLNO. We conclude that DLNO and, to a lesser extent, DLCO are compromised before HSCT mainly due to a DM,CO reduction. A further reduction of DM,CO without VC loss occurs after HSCT, possibly related to development of oedema, or interstitial fibrosis, or both.