A Simple and Safe Method for Checking the Position of Central Venous Catheters-A New and Reliable Threshold for Right Atrial Swirl Sign in Microbubbles Tests.

Background: Central venous catheters (CVCs) are indispensable tools in intensive care and emergency medicine. CVC malpositions still occur frequently and can cause various complications leading to increased patient mortality. A microbubbles test (MBT) can be used to confirm correct CVC positioning. However, there is serious doubt regarding whether the currently applied threshold of a 2 s push-to-bubbles time (PTB time) for rapid atrial swirl sign (RASS) in an MBT is reliable and accurate. The aim of the present study was to prove the quality of a new threshold: 1 s. Methods: Consecutive patients who were admitted to the intensive care unit (ICU) in a German neurological specialist hospital from 1 March 2021 to 20 July 2022 were enrolled. After ultrasound-guided CVC insertion, an MBT was performed, PTB time was measured, and RASS was interpreted. Additionally, a chest X-ray (CXR) was requested to check CVC position. Results: A total of 102 CVCs (98% jugular and 2% subclavian) were inserted in 102 patients (38% female and 62% male; median age: 66 years). Negative RASS (PTB time > 1 s) was observed in 2 out of 102 patients, resulting in an echocardiographic malposition rate of 2.0%. CXR confirmed the echocardiographic results. After correcting CVC position in the initially malpositioned CVCs, the PTB time was <1 s (positive RASS). The MBT protocol took about 0.5 min on average, while the CXR results were all available within 30 min. Sensitivity, specificity, and positive and negative predictive value were each 100% for the detection of CVC malpositions via an MBT using a threshold of 1 s compared to CXR. Conclusions: A new threshold of a 1 s PTB time for RASS in an MBT could detect CVC malpositions with excellent quality compared to CXR. Since the MBT was fast and safe and could be performed at the bedside, we propose that an MBT with the new and reliable threshold of 1 s should be routinely used in patient care.

Three-dimensional Doppler sonographic vascular imaging in regions with increased MR enhancement in inflamed wrists of patients with rheumatoid arthritis.

OBJECTIVE: To compare three-dimensional (3D) power Doppler ultrasonography (PDUS) with contrast enhanced magnetic resonance imaging (MRI) in their capability to visualize synovial vascularity in inflamed wrists of patients with rheumatoid arthritis (RA). METHODS: Nine patients with RA showing clinically active arthritis of the wrist as determined by tenderness and swelling were examined by contrast enhanced MRI and 3D PDUS. Vascularity close to and inside the joint capsule was visualized by conventional power Doppler mode. In a region with high Doppler signal intensity (=region of interest/ROI) a 3D blood vessel tree was obtained by a free-hand sweep. 3D images were evaluated with regard to the number of blood vessels in the intra- and peri-articular region. MRI examinations were performed using a 1.5 T Scanner. In MRI, time resolved coronal contrast enhanced T1-weighted sequences with fat suppression were acquired during an 8 min period to assess tissue enhancement. Relative enhancement was calculated and compared to 3D PDUS findings. RESULTS: A 3D vascular tree consisting of peri- and intra-articular blood vessels could be demonstrated in the same anatomical ROI in which an increased gadolinium enhancement was measured by MRI in all examined RA patients. The number of penetrating vessels into the joint capsule, the number of intra-articular vessels and a semiquantitative estimation of the strength of blood flow were used to generate a 3D score for the intensity of synovial vascularity. CONCLUSION: When compared with clinical symptoms and the gold standard dynamic MRI, 3D PDUS is a reliable imaging technique for assessing synovial vascularity in inflamed wrists of RA patients.

Leukotriene-mediated coronary vasoconstriction and loss of myocardial contractility evoked by low doses of Escherichia coli hemolysin in perfused rat hearts.

OBJECTIVE: hemolysin has been implicated as an important pathogenic factor in extraintestinal infections including sepsis. We investigated the effects of coronary administration of hemolysin on cardiac function in isolated rat hearts perfused at constant flow. DESIGN: Prospective, experimental study. SETTING: Research laboratory at a university hospital. SUBJECTS: Isolated hearts from male Wistar rats. INTERVENTIONS: Isolated hearts were perfused with purified hemolysin for 60 min. MEASUREMENTS AND MAIN RESULTS: Low concentrations of the toxin in the perfusate (0.1-0.2 hemolytic units/mL) caused a dose-dependent coronary vasoconstriction with a marked increase in coronary perfusion pressure, which was paralleled by a decrease in left ventricular developed pressure (and the maximum rate of left ventricular pressure increase). Moreover, 0.2 hemolytic units/mL hemolysin evoked ventricular fibrillation within 10 mins of toxin application. These events were accompanied by the liberation of leukotrienes (LTC4, LTD4, LTE4, and LTB4), thromboxane A2, prostaglandin I2, and the cell necrosis markers lactate dehydrogenase and creatine kinase into the recirculating perfusate. The lipoxygenase inhibitor MK-886 fully blocked the toxin-induced coronary vasoconstrictor response and the loss of myocardial contractility and reduced the release of lactate dehydrogenase and creatine kinase. In contrast to this, the cyclooxygenase inhibitor indomethacin was entirely ineffective. In addition, hemolysin elicited an increase in heart weight and left ventricular end-diastolic pressure, the latter again being suppressed by MK-886. CONCLUSIONS: Low doses of hemolysin cause strong coronary vasoconstriction, linked with loss of myocardial performance, release of cell injury enzymes, and electrical instability, with all events being largely attributable to toxin-elicited leukotriene generation in the coronary vasculature. Bacterial exotoxins such as hemolysin thus may be implicated in the cardiac abnormalities encountered in septic shock.