Alice F. Murray

Emergency thoracic ultrasound in the differentiation of the etiology of shortness of breath (ETUDES): sonographic B-lines and N-terminal pro-brain-type natriuretic peptide in diagnosing congestive heart failure.

OBJECTIVES Sonographic thoracic B-lines and N-terminal pro-brain-type natriuretic peptide (NT-ProBNP) have been shown to help differentiate between congestive heart failure (CHF) and chronic obstructive pulmonary disease (COPD). The authors hypothesized that ultrasound (US) could be used to predict CHF and that it would provide additional predictive information when combined with NT-ProBNP. They also sought to determine optimal two- and eight-zone scanning protocols when different thresholds for a positive scan were used. METHODS This was a prospective, observational study of a convenience sample of adult patients presenting to the emergency department (ED) with shortness of breath. Each patient had an eight-zone thoracic US performed by one of five sonographers, and serum NT-ProBNP levels were measured. Chart review by two physicians blinded to the US results served as the criterion standard. The operating characteristics of two- and eight-zone thoracic US alone, compared to, and combined with NT-ProBNP test results for predicting CHF were calculated using both dichotomous and interval likelihood ratios (LRs). RESULTS One-hundred patients were enrolled. Six were excluded because of incomplete data. Results of 94 patients were analyzed. A positive eight-zone US, defined as at least two positive zones on each side, had a positive likelihood ratio (LR+) of 3.88 (99% confidence interval [CI] = 1.55 to 9.73) and a negative likelihood ratio (LR-) of 0.5 (95% CI = 0.30 to 0.82), while the NT-ProBNP demonstrated a LR+ of 2.3 (95% CI = 1.41 to 3.76) and LR- of 0.24 (95% CI = 0.09 to 0.66). Using interval LRs for the eight-zone US test alone, the LR for a totally positive test (all eight zones positive) was infinite and for a totally negative test (no zones positive) was 0.22 (95% CI = 0.06 to 0.80). For two-zone US, interval LRs were 4.73 (95% CI = 2.10 to 10.63) when inferior lateral zones were positive bilaterally and 0.3 (95% CI = 0.13 to 0.71) when these were negative. These changed to 8.04 (95% CI = 1.76 to 37.33) and 0.11 (95% CI = 0.02 to 0.69), respectively, when congruent with NT-ProBNP. CONCLUSIONS Bedside thoracic US for B-lines can be a useful test for diagnosing CHF. Predictive accuracy is greatly improved when studies are totally positive or totally negative. A two-zone protocol performs similarly to an eight-zone protocol. Thoracic US can be used alone or can provide additional predictive power to NT-ProBNP in the immediate evaluation of dyspneic patients presenting to the ED.

Ultrasound Assessment for Extravascular Lung Water in Patients Undergoing Hemodialysis: Time Course for Resolution

BACKGROUND Sonographic B-lines, also known as lung comets, have been shown to correlate with the presence of extravascular lung water (EVLW). Absent in normal lungs, these sonographic findings become prominent as interstitia and alveoli fill with fluid. Characterization of the dynamics of B-lines, specifically their rate of disappearance as volume is removed, has not been previously described. In this study, we describe the dynamics of B-line resolution in patients undergoing hemodialysis. METHODS Patients undergoing hemodialysis underwent three chest ultrasound examinations: before, at the midpoint, and after dialysis. We followed a previously described chest ultrasound protocol that counts the number of B-lines visualized in 28 lung zones. Baseline demographics, assessment of ejection fraction, time elapsed, net volume of fluid removed, and subjective degree of shortness of breath were recorded for each patient. RESULTS Forty of 45 patients completed full dialysis runs and had all three lung scans performed; 6 of 40 patients had zero or one B-line predialysis, and none of these 6 patients gained B-lines during dialysis. Thirty-four of 40 patients had statistically significant reductions in the number of B-lines from predialysis to the midpoint scan and from predialysis to postdialysis with a p value < 0.001. There was no association between subjective dyspnea scores and number of B-lines removed. CONCLUSIONS B-line resolution appears to occur real-time as fluid is removed from the body, and this change was statistically significant. These data support thoracic ultrasound as a useful method for evaluating real-time changes in EVLW and in assessing a patients physiologic response to the removal of fluid. TRIAL REGISTRATION Massachusetts General Hospital trial registration protocol No. 2007P 002226.

Original ResearchChest UltrasonographyUltrasound Assessment for Extravascular Lung Water in Patients Undergoing Hemodialysis: Time Course for Resolution

BACKGROUND Sonographic B-lines, also known as lung comets, have been shown to correlate with the presence of extravascular lung water (EVLW). Absent in normal lungs, these sonographic findings become prominent as interstitia and alveoli fill with fluid. Characterization of the dynamics of B-lines, specifically their rate of disappearance as volume is removed, has not been previously described. In this study, we describe the dynamics of B-line resolution in patients undergoing hemodialysis. METHODS Patients undergoing hemodialysis underwent three chest ultrasound examinations: before, at the midpoint, and after dialysis. We followed a previously described chest ultrasound protocol that counts the number of B-lines visualized in 28 lung zones. Baseline demographics, assessment of ejection fraction, time elapsed, net volume of fluid removed, and subjective degree of shortness of breath were recorded for each patient. RESULTS Forty of 45 patients completed full dialysis runs and had all three lung scans performed; 6 of 40 patients had zero or one B-line predialysis, and none of these 6 patients gained B-lines during dialysis. Thirty-four of 40 patients had statistically significant reductions in the number of B-lines from predialysis to the midpoint scan and from predialysis to postdialysis with a p value < 0.001. There was no association between subjective dyspnea scores and number of B-lines removed. CONCLUSIONS B-line resolution appears to occur real-time as fluid is removed from the body, and this change was statistically significant. These data support thoracic ultrasound as a useful method for evaluating real-time changes in EVLW and in assessing a patients physiologic response to the removal of fluid. TRIAL REGISTRATION Massachusetts General Hospital trial registration protocol No. 2007P 002226.

Optic nerve sheath diameter correlates with the presence and severity of acute mountain sickness: evidence for increased intracranial pressure

Increased intracranial pressure is suspected in the pathogenesis of acute mountain sickness (AMS), but no studies have correlated it with the presence or severity of AMS. We sought to determine whether increased optic nerve sheath diameter, a surrogate measure of intracranial pressure, is associated with the presence and severity of AMS. We performed a cross-sectional study of travelers ascending through Pheriche, Nepal (4,240 m), from March 3 to May 14, 2006. AMS was assessed using the Lake Louise score. Optic nerve sheath diameter was measured by ultrasound. Ultrasound exams were performed and read by separate blinded observers. Two-hundred eighty seven subjects were enrolled. Ten of these underwent repeat examination. Mean optic nerve sheath diameter was 5.34 mm [95% confidence interval (CI) 5.18-5.51 mm] in the 69 subjects with AMS vs. 4.46 mm (95% CI 4.39-4.54 mm) in the 218 other subjects (P < 0.0001). There was also a positive association between optic nerve sheath diameter and total Lake Louise score (P for trend < 0.0001). In a multivariate logistic regression model of factors associated with AMS, optic nerve sheath diameter was strongly associated with AMS (odds ratio 6.3; 95% CI, 3.7-10.8; P < 0.001). In 10 subjects with repeat examinations, change in Lake Louise score had a strong positive correlation with change in optic nerve sheath diameter (R(2) = 0.84, P < 0.001). Optic nerve sheath diameter, a proxy for intracranial pressure, is associated with the presence and severity of AMS.

Focused Maternal Ultrasound by Midwives in Rural Zambia

Point-of-care ultrasound is being increasingly implemented in resource-poor settings in an ad hoc fashion. We developed a focused maternal ultrasound-training program for midwives in a rural health district in Zambia. Four hundred forty-one scans were recorded by 21 midwives during the 6-month study period. In 74 scans (17%), the ultrasound findings prompted a change in clinical decision-making. Eight of the midwives were evaluated with a 14-question observed structured clinical examination (OSCE) and demonstrated a slight overall improvement with mean scores at 2 and 6 months of 10.0/14 (71%) and 11.6/14 (83%), respectively. Our pilot project demonstrates that midwives in rural Zambia can be trained to perform basic obstetric ultrasound and that it impacts clinical decision-making. Ultrasound skills were retained over the study period. More data is necessary to determine whether the introduction of ultrasound ultimately improves outcomes of pregnant women in rural Zambia.

Faculty staff-guided versus self-guided ultrasound training for internal medicine residents

Ultrasonography is of growing importance within internal medicine (IM), but the optimal method of training doctors to use it is uncertain. In this study, the authors provide the first objective comparison of two approaches to training IM residents in ultrasonography.

Real-time resolution of sonographic B-lines in a patient with pulmonary edema on continuous positive airway pressure

Sonographic B-lines of the lungs have been shown to be able to differentiate between congestive heart failure and chronic obstructive pulmonary disease. Studies have shown that B-lines are often present on presentation and resolve during the course of a hospitalization. What is not known is how quickly B-lines resolve in response to treatment. We describe a case of a patient who presented with pulmonary edema and had diffuse B-lines seen on bedside thoracic ultrasound. She was treated with continuous positive airway pressure only and, a few hours later, had no sonographic Blines. B-lines seen on bedside thoracic ultrasound resolve in real time when pulmonary edema is treated with continuous positive airway pressure. Research to further quantify the use of B-lines in monitoring response to treatment is needed. Thoracic ultrasound has been shown to be a useful way of evaluating patients with dyspnea. Specifically, the presence of diffuse sonographic B-lines is associated with fluid overload states such as pulmonary edema. Although studies have shown that B-lines can aid in the diagnosis of this condition, none have looked at their rate of resolution with treatment. We describe an interesting case of a patient in pulmonary edema whose B-lines resolve in real time when treated with continuous positive airway pressure (CPAP) only. An 82-year-old woman presented to the emergency department (ED) with dyspnea for 4 hours. She had a history of atrial fibrillation, congestive heart failure (CHF), end-stage renal disease, hypertension, and coronary artery disease. She was sitting on her couch in her usual state of health watching TV when she suddenly became short of breath. She had a mild nonproductive cough but denied fever, chest pain, or leg pain. She had been compliant with her medications and with hemodialysis sessions. She had been using 2 to 3 pillows to sleep at night for a while. She reported some intermittent leg swelling, which improves after dialysis. 0735-6757/

New-Onset Anxiety Disorders at High Altitude

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A Practical Guide to Self-Sustaining Point-of-Care Ultrasound Education Programs in Resource-Limited Settings

Abstract Objective.—Studies on the neurologic effects of high-altitude travel have focused on psychometric and cognitive testing and the long-term effects of hypoxia on memory and cognition. Few authors have discussed overt clinical psychiatric illness during high-altitude travel, and those few have focused on patients with preexisting psychiatric diagnoses. We describe a series of patients with new-onset anxiety disorders at high altitude treated at the Himalayan Rescue Association (HRA) clinic in Pheriche, Nepal (4240 m) in the spring season of 2006. Methods.—We report on all 6 cases of anxiety-related illness diagnosed at the HRA Pheriche Clinic during the spring season, 2006. Three cases, representing the 3 discrete types of illness we encountered, are described in detail. Results.—Six of 76 foreign patients and none of the 224 Nepalis seen during the season had anxiety-related primary diagnoses. None of the 6 patients had a history of psychiatric disorders or anxiety-related problems at low altitude. Three of the 6 patients were seen after hours, and all 6 required multiple visits. We describe 3 types of anxiety-related disorders: limited-symptom panic attacks induced by nocturnal periodic breathing, excessive health-related anxiety, and excessive emotionality. Conclusions.—Anxiety-related illness requires significant use of medical resources by high-altitude travelers. Further research is needed to define the epidemiology of anxiety-related disorders at high altitude, to quantify the contributions of various etiologic factors, and to identify safe, effective treatments.

Ultrasound for High Altitude Research

The value of point-of-care ultrasound education in resource-limited settings is increasingly recognized, though little guidance exists on how to best construct a sustainable training program. Herein we offer a practical overview of core factors to consider when developing and implementing a point-of-care ultrasound education program in a resource-limited setting. Considerations include analysis of needs assessment findings, development of locally relevant curriculum, access to ultrasound machines and related technological and financial resources, quality assurance and follow-up plans, strategic partnerships, and outcomes measures. Well-planned education programs in these settings increase the potential for long-term influence on clinician skills and patient care.