Reproducibility of point-of-care ultrasonography for central vein diameter measurement: Separating image acquisition from interpretation.

PURPOSE: Central vein point-of-care ultrasonography must be reproducible to detect intravascular volume changes. We sought to determine which measurement step, image acquisition or interpretation, could be more compromising for reproducibility. METHODS: Three investigators each acquired inferior vena cava (IVC) and internal jugular (IJV) vein ultrasonographic sequences (US) from a convenience sample of 21 hospitalized general medicine participants and then interpreted each US three separate times. We partitioned the random errors of acquisition and interpretation, attributing wider dispersions of each to larger reductions in reproducibility. RESULTS: We analyzed 351 interpretations of 39 IVC and 432 interpretations of 48 IJV US. Reproducibility of the maximum (standard error of measurement 3.3 mm [95% confidence interval, CI 2.7-4.2 mm]) and minimum (4.8 mm [3.9-6.3 mm]) IVC diameter measurements were worse than that of the mediolateral (2.5 mm [2.0-3.2 mm]) and anteroposterior (2.5 mm [2.0-3.1 mm]) IJV diameters. The dispersions of random measurement errors were wider among acquisitions than interpretations. CONCLUSIONS: Among our investigators, central vein diameter measurements obtained by point-of-care ultrasonography are not sufficiently reproducible to distinguish clinically meaningful intravascular volume changes from measurement errors. Reproducibility could be most effectively improved by reducing the random measurement errors of acquisition. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:488-496, 2017.

An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea.

BACKGROUND: Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome. PURPOSE: The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea. METHODS: An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members. RESULTS: Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains. CONCLUSIONS: Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.

Guidelines versus clinical practice in antimicrobial therapy for COPD.

Limited information is available about current practice patterns involving the use of antibiotics in the inpatient management of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). We sought to characterize current patterns of antibiotic use and to compare them to evidence-based guidelines. This study is a retrospective case series of patients at a regional tertiary care medical center. Charts were reviewed to identify patients admitted between January 2006 and 2008 with an initial diagnosis of AECOPD who had no evidence of another infectious process and who were not immunocompromised. Relevant data extracted from charts included initial clinical presentation, antibiotic administration, microbiological studies, and hospital course. One hundred sixteen admissions meeting inclusion criteria were identified. There was no statistically significant relationship between the presence of an established indication for antibiotic administration and the use of antibiotics, with roughly 75% of patients in all groups receiving therapy. A significant fraction of patients received combination therapy that was more appropriate for the management of pneumonia than for AECOPD. There were significant deviations between practice patterns and guidelines regarding the use and selection of antibiotics. Some of these may reflect areas of uncertainty in the primary literature and varying sets of guidelines.

Limited agreement between two noninvasive measurements of blood volume during fluid removal: ultrasound of inferior vena cava and finger-clip spectrophotometry of hemoglobin concentration.

OBJECTIVE: Plots of blood volume measurements over time (profiles) may identify euvolemia during fluid removal for acute heart failure. We assessed agreement between two noninvasive measurements of blood volume profiles during mechanical fluid removal, which exemplifies the interstitial fluid shifts that occur during diuretic-induced fluid removal. APPROACH: During hemodialysis we compared change in maximum diameter of the inferior vena cava by ultrasound ([Formula: see text]) to change in relative blood volume derived from capillary hemoglobin concentration from finger-clip spectrophotometry (RBVSpHb). We grouped profiles of these measurements into three distinct shapes using an unbiased, data-driven modeling technique. METHODS: Fifty patients who were not in acute heart failure underwent a mean of five paired measurements while an average of 1.3 liters of fluid was removed over 2 h during single hemodialysis sessions. [Formula: see text] changed -1.0 mm (95% CI -1.9 to -0.2 mm) and the RBVSpHb changed -1.1% (95% CI -2.7 to +0.5%), but these changes were not correlated (r -0.04, 95% CI -0.32 to +0.24). Nor was there agreement between categorization of profiles of change in the two measurements (kappa -0.1, 95% CI -0.3 to +0.1). SIGNIFICANCE: [Formula: see text] and RBVSpHb estimates of blood volume do not agree during mechanical fluid removal, likely because regional changes in blood flow and pressure modify IVC dimensions as well as changes total blood volume.

Clinical measurements obtained from point-of-care ultrasound images to assess acquisition skills.

BACKGROUND: Current methods of assessing competence in acquiring point-of-care ultrasound images are inadequate. They rely upon cumbersome rating systems that do not depend on the actual outcome measured and lack evidence of validity. We describe a new method that uses a rigorous statistical model to assess performance of individual trainees based on the actual task, image acquisition. Measurements obtained from the images acquired (the actual desired outcome) are themselves used to validate effective training and competence acquiring ultrasound images. We enrolled a convenience sample of 21 spontaneously breathing adults from a general medicine ward. In random order, two trainees (A and B) and an instructor contemporaneously acquired point-of-care ultrasound images of the inferior vena cava and the right internal jugular vein from the same patients. Blinded diameter measurements from each ultrasound were analyzed quantitatively using a multilevel model. Consistent mean differences between each trainee's and the instructor's images were ascribed to systematic acquisition errors, indicative of poor measurement technique and a need for further training. Wider variances were attributed to sporadic errors, indicative of inconsistent application of measurement technique across patients. In addition, the instructor recorded qualitative observations of each trainee's performance during image acquisition. RESULTS: For all four diameters, the means and variances of measurements from trainee A's images differed significantly from the instructor's, whereas those from trainee B's images were comparable. Techniques directly observed by the instructor supported these model-derived findings. For example, mean anteroposterior diameters of the internal jugular vein obtained from trainee A's images were 3.8 mm (90% CI 2.3-5.4) smaller than from the instructor's; this model-derived finding matched the instructor's observation that trainee A compressed the vein during acquisition. Instructor summative assessments agreed with model-derived findings, providing internal validation of the descriptive and quantitative assessments of competence acquiring ultrasound images. CONCLUSIONS: Clinical measurements obtained from point-of-care ultrasound images acquired contemporaneously by trainees and an instructor can be used to quantitatively assess the image acquisition competence of specific trainees. This method may obviate resource-intensive qualitative rating systems that are based on ultrasound image quality and direct observation, while also helping instructors guide remediation.

A rare cause of postoperative hypotension.

A 62-year-old woman presented with a 3-month history of abdominal distension and decreased exercise tolerance. A chest radiograph showed a probable left pleural effusion (Fig 1). A CT scan of the abdomen revealed a solid ovarian mass with omental caking and a large volume of ascites; there was also confirmation of a left pleural effusion. Three days before surgery a CT pulmonary angiogram (CTPA) showed no evidence of pulmonary thromboembolism (PTE). The patient had some improvement in her symptoms after paracentesis and thoracentesis with drainage of 2,000 mL and 250 mL of fluid, respectively. She underwent total abdominal hysterectomy, bilateral oophorectomy, and partial sigmoid resection with an estimated blood loss of 850 mL. During the operation, she received 5 L of crystalloid and required phenylephrine at 40 to 80 µg/min to maintain a mean arterial pressure > 65 mm Hg. She was extubated after surgery, but immediately after extubation, she became markedly hypotensive and hypoxemic with a BP of 50/20 mm Hg and an oxygen saturation of 70%. An ECG showed T-wave inversions from V1 to V5 and an S1Q3T3 pattern (Fig 2). A bedside echocardiogram showed an enlarged right ventricle (RV), septal dyskinesia, and obliteration of the left ventricle, all consistent with systolic and diastolic RV overload (Fig 3).

Inappropriate ventilator triggering caused by an in-line suction catheter.

OBJECTIVE: To examine the phenomenon of inappropriate triggering caused by an in-line suction catheter. DESIGN: We used a test lung to assess inappropriate triggering in four ventilators with both pressure and flow triggering. RESULTS: With pressure triggering, inappropriate triggering occurred only in the presence of PEEP. However, with flow triggering, inappropriate triggering occurred both with and without PEEP. Inappropriate triggering did not occur in a model of severe airflow obstruction. CONCLUSION: In-line suction catheters may lead to inappropriate triggering and potentially dangerous increases in delivered ventilation.

Termination of inspiration by phase-dependent respiratory vagal feedback in awake normal humans.

Imperceptible levels of proportional assist ventilation applied throughout inspiration reduced inspiratory time (TI) in awake humans. More recently, the reduction in TI was associated with flow assist, but flow assist also reaches a maximum value early during inspiration. To test the separate effects of flow assist and timing of assist, we applied a pseudorandom binary sequence of flow-assisted breaths during early, late, or throughout inspiration in eight normal subjects. We hypothesized that imperceptible flow assist would shorten TI most effectively when applied during early inspiration. Tidal volume, integrated respiratory muscle pressure per breath, TI, and TE were recorded. All stimuli (early, late, or flow assist applied throughout inspiration) resulted in a significant increase in inspiratory flow; however, only when the flow assist was applied during early inspiration was there a significant reduction in TI and the integrated respiratory muscle pressure per breath. These results provide further evidence that vagal feedback modulates breathing on a breath-by-breath basis in conscious humans within a physiological range of breath sizes.

An official American Thoracic Society workshop report: assessment and palliative management of dyspnea crisis.

In 2009, the American Thoracic Society (ATS) funded an assembly project, Palliative Management of Dyspnea Crisis, to focus on identification, management, and optimal resource utilization for effective palliation of acute episodes of dyspnea. We conducted a comprehensive search of the medical literature and evaluated available evidence from systematic evidence-based reviews (SEBRs) using a modified AMSTAR approach and then summarized the palliative management knowledge base for participants to use in discourse at a 2009 ATS workshop. We used an informal consensus process to develop a working definition of this novel entity and established an Ad Hoc Committee on Palliative Management of Dyspnea Crisis to further develop an official ATS document on the topic. The Ad Hoc Committee members defined dyspnea crisis as "sustained and severe resting breathing discomfort that occurs in patients with advanced, often life-limiting illness and overwhelms the patient and caregivers' ability to achieve symptom relief." Dyspnea crisis can occur suddenly and is characteristically without a reversible etiology. The workshop participants focused on dyspnea crisis management for patients in whom the goals of care are focused on palliation and for whom endotracheal intubation and mechanical ventilation are not consistent with articulated preferences. However, approaches to dyspnea crisis may also be appropriate for patients electing life-sustaining treatment. The Ad Hoc Committee developed a Workshop Report concerning assessment of dyspnea crisis; ethical and professional considerations; efficient utilization, communication, and care coordination; clinical management of dyspnea crisis; development of patient education and provider aid products; and enhancing implementation with audit and quality improvement.

Tuberculosis-induced tracheobronchial stenosis during pregnancy.

Central airway stenosis is extremely rare in pregnancy and could lead to respiratory and cardiovascular embarrassment, especially at the time of delivery. Initially, patients may not show obvious signs of respiratory difficulty. Early recognition of the disease and anticipatory management of a complicated delivery are very important. We present a pregnant patient with tuberculosis-induced severe tracheobronchial stenosis and discuss the management challenges of her delivery.

American College of Chest Physicians consensus statement on the management of dyspnea in patients with advanced lung or heart disease.

BACKGROUND: This consensus statement was developed based on the understanding that patients with advanced lung or heart disease are not being treated consistently and effectively for relief of dyspnea. METHODS: A panel of experts was convened. After a literature review, the panel developed 23 statements covering five domains that were considered relevant to the topic condition. Endorsement of these statements was assessed by levels of agreement or disagreement on a five-point Likert scale using two rounds of the Delphi method. RESULTS: The panel defined the topic condition as "dyspnea that persists at rest or with minimal activity and is distressful despite optimal therapy of advanced lung or heart disease." The five domains were: measurement of patient-reported dyspnea, oxygen therapy, other therapies, opioid medications, and ethical issues. In the second round of the Delphi method, 34 of 56 individuals (61%) responded, and agreement of at least 70% was achieved for 20 of the 23 statements. CONCLUSIONS: For patients with advanced lung or heart disease, we suggest that: health-care professionals are ethically obligated to treat dyspnea, patients should be asked to rate the intensity of their breathlessness as part of a comprehensive care plan, opioids should be dosed and titrated for relief of dyspnea in the individual patient, both the patient and clinician should reassess whether specific treatments are serving the goal of palliating dyspnea without causing adverse effects, and it is important for clinicians to communicate about palliative and end-of-life care with their patients.

Acute respiratory distress syndrome.

Acute respiratory distress syndrome is the clinical manifestation of severe, acute lung injury. It is characterized by the acute onset of diffuse, bilateral pulmonary infiltrates secondary to noncardiogenic pulmonary edema, refractory hypoxia, and decreased lung compliance. Acute respiratory distress syndrome occurs most frequently in the setting of sepsis, aspiration of gastric contents, trauma, or multiple transfusions. Its complex pathophysiology involves an inciting local or systemic event that initiates pulmonary endothelial and epithelial damage and subsequent increased permeability. Tachypnea, hypoxia, and respiratory alkalosis are typical early clinical manifestations, and they are usually followed by the appearance of diffuse pulmonary infiltrates and respiratory failure within 48 hours. Early identification and treatment of the underlying disorder, along with aggressive supportive care, are essential. Experimental therapies, including those using nitric oxide and surfactant, have not been shown to improve mortality in patients with ARDS, but new therapeutic approaches such as low-volume ventilation have been shown to decrease mortality. Many patients who survive ARDS have permanent, mild to moderate impairment of lung function. Quality of life after hospitalization with ARDS may be poorer than that in similar patients without ARDS.