Diaphragm ultrasonography is rapidly evolving in both critical care and research. Nevertheless, methodologically robust guidelines on its methodology and acquiring expertise do not, or only ...partially, exist. Therefore, we set out to provide consensus-based statements towards a universal measurement protocol for diaphragm ultrasonography and establish key areas for research.
To formulate a robust expert consensus statement, between November 2020 and May 2021, a two-round, anonymous and online survey-based Delphi study among experts in the field was performed. Based on the literature review, the following domains were chosen: "Anatomy and physiology", "Transducer Settings", "Ventilator Impact", "Learning and expertise", "Daily practice" and "Future directions". Agreement of ≥ 68% (≥ 10 panelists) was needed to reach consensus on a question.
Of 18 panelists invited, 14 agreed to participate in the survey. After two rounds, the survey included 117 questions of which 42 questions were designed to collect arguments and opinions and 75 questions aimed at reaching consensus. Of these, 46 (61%) consensus was reached. In both rounds, the response rate was 100%. Among others, there was agreement on measuring thickness between the pleura and peritoneum, using > 10% decrease in thickness as cut-off for atrophy and using 40 examinations as minimum training to use diaphragm ultrasonography in clinical practice. In addition, key areas for research were established.
This expert consensus statement presents the first set of consensus-based statements on diaphragm ultrasonography methodology. They serve to ensure high-quality and homogenous measurements in daily clinical practice and in research. In addition, important gaps in current knowledge and thereby key areas for research are established. Trial registration The study was pre-registered on the Open Science Framework with registration digital object identifier https://doi.org/10.17605/OSF.IO/HM8UG .
Insertion of a central venous catheter (CVC) is common practice in critical care medicine. Complications arising from CVC placement are mostly due to a pneumothorax or malposition. Correct position ...is currently confirmed by chest x-ray, while ultrasonography might be a more suitable option. We performed a meta-analysis of the available studies with the primary aim of synthesizing information regarding detection of CVC-related complications and misplacement using ultrasound (US).
This is a systematic review and meta-analysis registered at PROSPERO (CRD42016050698). PubMed, EMBASE, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials were searched. Articles which reported the diagnostic accuracy of US in detecting the position of CVCs and the mechanical complications associated with insertion were included. Primary outcomes were specificity and sensitivity of US. Secondary outcomes included prevalence of malposition and pneumothorax, feasibility of US examination, and time to perform and interpret both US and chest x-ray. A qualitative assessment was performed using the QUADAS-2 tool.
We included 25 studies with a total of 2548 patients and 2602 CVC placements. Analysis yielded a pooled specificity of 98.9 (95% confidence interval (CI): 97.8-99.5) and sensitivity of 68.2 (95% CI: 54.4-79.4). US examination was feasible in 96.8% of the cases. The prevalence of CVC malposition and pneumothorax was 6.8% and 1.1%, respectively. The mean time for US performance was 2.83 min (95% CI: 2.77-2.89 min) min, while chest x-ray performance took 34.7 min (95% CI: 32.6-36.7 min). US was feasible in 97%. Further analyses were performed by defining subgroups based on the different utilized US protocols and on intra-atrial and extra-atrial misplacement. Vascular US combined with transthoracic echocardiography was most accurate.
US is an accurate and feasible diagnostic modality to detect CVC malposition and iatrogenic pneumothorax. Advantages of US over chest x-ray are that it can be performed faster and does not subject patients to radiation. Vascular US combined with transthoracic echocardiography is advised. However, the results need to be interpreted with caution since included studies were often underpowered and had methodological limitations. A large multicenter study investigating optimal US protocol, among other things, is needed.
Intramolecular photostabilization via triple-state quenching was recently revived as a tool to impart synthetic organic fluorophores with 'self-healing' properties. To date, utilization of such ...fluorophore derivatives is rare due to their elaborate multi-step synthesis. Here we present a general strategy to covalently link a synthetic organic fluorophore simultaneously to a photostabilizer and biomolecular target via unnatural amino acids. The modular approach uses commercially available starting materials and simple chemical transformations. The resulting photostabilizer-dye conjugates are based on rhodamines, carbopyronines and cyanines with excellent photophysical properties, that is, high photostability and minimal signal fluctuations. Their versatile use is demonstrated by single-step labelling of DNA, antibodies and proteins, as well as applications in single-molecule and super-resolution fluorescence microscopy. We are convinced that the presented scaffolding strategy and the improved characteristics of the conjugates in applications will trigger the broader use of intramolecular photostabilization and help to emerge this approach as a new gold standard.
To determine the diagnostic accuracy of lung ultrasound signs for both the diagnosis of interstitial syndrome and for the discrimination of noncardiogenic interstitial syndrome (NCIS) from ...cardiogenic pulmonary edema (CPE) in a mixed ICU population.
A prospective diagnostic accuracy study with derivation and validation cohorts.
Three academic mixed ICUs in the Netherlands.
Consecutive adult ICU patients that received a lung ultrasound examination.
None.
The reference standard was the diagnosis of interstitial syndrome (NCIS or CPE) or noninterstitial syndromes (other pulmonary diagnoses and no pulmonary diagnoses) based on full post-hoc clinical chart review except lung ultrasound. The index test was a lung ultrasound examination performed and scored by a researcher blinded to clinical information. A total of 101 patients were included in the derivation and 122 in validation cohort. In the derivation cohort, patients with interstitial syndrome ( n = 56) were reliably discriminated from other patients based on the presence of a B-pattern (defined as greater than or equal to 3 B-lines in one frame) with an accuracy of 94.7% (sensitivity, 90.9%; specificity, 91.1%). For discrimination of NCIS ( n = 29) from CPE ( n = 27), the presence of bilateral pleural line abnormalities (at least two: fragmented, thickened or irregular) had the highest diagnostic accuracy (94.6%; sensitivity, 89.3%; specificity, 100%). A diagnostic algorithm (Bedside Lung Ultrasound for Interstitial Syndrome Hierarchy protocol) using B-pattern and bilateral pleural abnormalities had an accuracy of 0.86 (95% CI, 0.77-0.95) for diagnosis and discrimination of interstitial syndromes. In the validation cohort, which included 122 patients with interstitial syndrome, bilateral pleural line abnormalities discriminated NCIS ( n = 98) from CPE ( n = 24) with a sensitivity of 31% (95% CI, 21-40%) and a specificity of 100% (95% CI, 86-100%).
Lung ultrasound can diagnose and discriminate interstitial syndromes in ICU patients with moderate-to-good accuracy. Pleural line abnormalities are highly specific for NCIS, but sensitivity is limited.
To determine the diagnostic accuracy of extended lung ultrasonographic assessment, including evaluation of dynamic air bronchograms and color Doppler imaging to differentiate pneumonia and ...atelectasis in patients with consolidation on chest radiograph. Compare this approach to the Simplified Clinical Pulmonary Infection Score, Lung Ultrasound Clinical Pulmonary Infection Score, and the Bedside Lung Ultrasound in Emergency protocol.
Prospective diagnostic accuracy study.
Adult ICU applying selective digestive decontamination.
Adult patients that underwent a chest radiograph for any indication at any time during admission. Patients with acute respiratory distress syndrome, coronavirus disease 2019, severe thoracic trauma, and infectious isolation measures were excluded.
None.
Lung ultrasound was performed within 24 hours of chest radiograph. Consolidated tissue was assessed for presence of dynamic air bronchograms and with color Doppler imaging for presence of flow. Clinical data were recorded after ultrasonographic assessment. The primary outcome was diagnostic accuracy of dynamic air bronchogram and color Doppler imaging alone and within a decision tree to differentiate pneumonia from atelectasis. Of 120 patients included, 51 (42.5%) were diagnosed with pneumonia. The dynamic air bronchogram had a 45% (95% CI, 31-60%) sensitivity and 99% (95% CI, 92-100%) specificity. Color Doppler imaging had a 90% (95% CI, 79-97%) sensitivity and 68% (95% CI, 56-79%) specificity. The combined decision tree had an 86% (95% CI, 74-94%) sensitivity and an 86% (95% CI, 75-93%) specificity. The Bedside Lung Ultrasound in Emergency protocol had a 100% (95% CI, 93-100%) sensitivity and 0% (95% CI, 0-5%) specificity, while the Simplified Clinical Pulmonary Infection Score and Lung Ultrasound Clinical Pulmonary Infection Score had a 41% (95% CI, 28-56%) sensitivity, 84% (95% CI, 73-92%) specificity and 68% (95% CI, 54-81%) sensitivity, 81% (95% CI, 70-90%) specificity, respectively.
In critically ill patients with pulmonary consolidation on chest radiograph, an extended lung ultrasound protocol is an accurate and directly bedside available tool to differentiate pneumonia from atelectasis. It outperforms standard lung ultrasound and clinical scores.
Evidence from previous studies comparing lung ultrasound to thoracic computed tomography (CT) in intensive care unit (ICU) patients is limited due to multiple methodologic weaknesses. While ...addressing methodologic weaknesses of previous studies, the primary aim of this study is to investigate the diagnostic accuracy of lung ultrasound in a tertiary ICU population.
This is a single-center, prospective diagnostic accuracy study conducted at a tertiary ICU in the Netherlands. Critically ill patients undergoing thoracic CT for any clinical indication were included. Patients were excluded if time between the index and reference test was over eight hours. Index test and reference test consisted of 6-zone lung ultrasound and thoracic CT, respectively. Hemithoraces were classified by the index and reference test as follows: consolidation, interstitial syndrome, pneumothorax and pleural effusion. Sensitivity, specificity, positive and negative likelihood ratio were estimated.
In total, 87 patients were included of which eight exceeded the time limit and were subsequently excluded. In total, there were 147 respiratory conditions in 79 patients. The estimated sensitivity and specificity to detect consolidation were 0.76 (95%CI: 0.68 to 0.82) and 0.92 (0.87 to 0.96), respectively. For interstitial syndrome they were 0.60 (95%CI: 0.48 to 0.71) and 0.69 (95%CI: 0.58 to 0.79). For pneumothorax they were 0.59 (95%CI: 0.33 to 0.82) and 0.97 (95%CI: 0.93 to 0.99). For pleural effusion they were 0.85 (95%CI: 0.77 to 0.91) and 0.77 (95%CI: 0.62 to 0.88).
In conclusion, lung ultrasound is an adequate diagnostic modality in a tertiary ICU population to detect consolidations, interstitial syndrome, pneumothorax and pleural effusion. Moreover, one should be careful not to interpret lung ultrasound results in deterministic fashion as multiple respiratory conditions can be present in one patient. Trial registration This study was retrospectively registered at Netherlands Trial Register on March 17, 2021, with registration number NL9344.
While buffer cocktails remain the most commonly used method for photostabilization and photoswitching of fluorescent markers, intramolecular triplet-state quenchers emerge as an alternative strategy ...to impart fluorophores with 'self-healing' or even functional properties such as photoswitching. In this contribution, we evaluated combinations of both approaches and show that inter- and intramolecular triplet-state quenching processes compete with each other. We find that although the rate of triplet-state quenching is additive, the photostability is limited by the faster pathway. Often intramolecular processes dominate the photophysical situation for combinations of covalently-linked and solution-based photostabilizers and photoswitching agents. Furthermore we show that intramolecular photostabilizers can protect fluorophores from reversible off-switching events caused by solution-additives, which was previously misinterpreted as photobleaching. Our studies also provide practical guidance for usage of photostabilizer-dye conjugates for STORM-type super-resolution microscopy permitting the exploitation of their improved photophysics for increased spatio-temporal resolution. Finally, we provide evidence that the biochemical environment, e.g., proximity of aromatic amino-acids such as tryptophan, reduces the photostabilization efficiency of commonly used buffer cocktails. Not only have our results important implications for a deeper mechanistic understanding of self-healing dyes, but they will provide a general framework to select label positions for optimal and reproducible photostability or photoswitching kinetics in different biochemical environments.
•Discriminating interstitial syndromes (NCIS and CPE) on the ICU is difficult.•Clinicians familiar with LUS may use gestalt; a subjective impression of LUS images.•LUS-gestalt aids the discrimination ...of NCIS from CPE (91.1% diagnostic accuracy).
Fluorescence is a versatile tool for spectroscopic investigations and imaging of dynamic processes and structures across various scientific disciplines. The photophysical performance, that is, signal ...stability and signal duration, of the employed fluorophores is a major limiting factor. In this Letter, we propose a general concept to covalently link molecules, which are known for their positive effect in photostabilization, to form a combined photostabilizer with new properties. The direct linkage of two (or more) photostabilizers will allow one to obtain combined or synergetic effects in fluorophore stabilization and can simplify the preparation of imaging buffers that would otherwise require a mixture of photostabilizers for optimal performance. This concept was explored by synthesizing a molecule with a reducing and oxidizing moiety that is referred to as internal ROXS or “iROXS”. Using single-molecule fluorescence microscopy, inter- and intramolecular healing of iROXS was observed, that is, strongly reduced blinking and increased photostability of the cyanine fluorophore Cy5. Moreover, it is shown that a covalently coupled photostabilizer can replace a mixture of molecules needed to make a functional photostabilizing ROXS buffer and might hence represent the new standard for defined and reproducible imaging conditions in single-molecule experiments. In self-healing fluorophores with intramolecular triplet-state quenching, an unprecedented photostability increase of >100-fold was obtained when using iROXS, which is even competitive with solution-based healing. Control experiments show that the oxidizing part of the iROXS molecule, an aromatic nitro group, dominates the healing process. The suggested synthetic concept and the proof-of-concept experiments represent the starting point for the quest to identify optimal combinations of linked photostabilizers for various fluorescence applications.
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