Nathan A. Teismann

Accuracy of emergency physicians using ultrasound to determine gestational age in pregnant women.

INTRODUCTION Rapid and accurate determination of gestational age may be vital to the appropriate care of the critically ill pregnant patient. Before the use of emergency ultrasound, physical examination of fundal height (FH) in the nonverbal patient was considered the quickest method to estimate gestational age. We conducted a prospective, observational study of the performance of bedside sonography to determine gestational age. METHODS We enrolled a convenience sample of women in their second or third trimester of pregnancy. Emergency physicians (EPs) made ultrasound measurements of fetal biparietal diameter (BPD) and femur length, followed by a measurement of FH. These measurements were compared with true gestational age (TGA), sonography by an ultrasound technician, and measurement of FH performed by an obstetrician. Main outcome measures were the average time needed to complete measurements; correlation coefficients between EP measurements and those made by an ultrasound technician, an obstetrician, and TGA, and overall accuracy to determine fetal age greater than 24 weeks. RESULTS The average time to complete ultrasound measurements was less than 1 minute. When physician-performed measurements were compared with TGA, the correlation coefficients were 0.947 (0.926-0.968) for BPD, 0.957 (0.941-0.973) for femur length, and 0.712 (0.615-0.809) for FH. When determining fetal viability, EPs overall accuracy was 96% using ultrasound and 80% using FH. CONCLUSIONS With brief training, EPs can quickly and accurately determine gestational age using ultrasound, and these estimates may be more accurate than those obtained through physical examination. Emergency physicians should consider using ultrasound in emergent evaluation of pregnant patients who are unable to provide history.

Is the Ordering of Imaging for Suspected Venous Thromboembolism Consistent With D-dimer Result?

STUDY OBJECTIVE We assessed whether the ordering of imaging studies in patients with suspected venous thromboembolism was consistent with the results of D-dimer testing. METHODS We performed a retrospective chart review of consecutive cases in which a D-dimer assay was performed at an urban academic emergency department during a 13-month period. Measurements included D-dimer result and results of imaging for venous thromboembolism. The primary outcome measure was the percentage of patients in each D-dimer category (positive or negative result with a cutoff value of 500 ng fibrinogen equivalent units/dL) who underwent subsequent imaging within 48 hours. We also report the results of the imaging studies obtained. RESULTS A total of 553 D-dimer tests were ordered, with 266 (48.1%) negative and 287 (51.9%) positive results. Of patients with a negative D-dimer result, 37 (14%; 95% confidence interval [CI] 10% to 19%) underwent at least 1 imaging study. Of patients with a positive D-dimer result, 137 (48%; 95% CI 42% to 54%) did not undergo imaging. CONCLUSION Evaluation for venous thromboembolism occasionally proceeded despite a negative D-dimer result, whereas frequently no further evaluation occurred despite a positive result. These findings suggest that actual clinical practice differs from what is recommended by published algorithms that guide evaluation of patients with suspected venous thromboembolism.

Point-of-care Ocular Ultrasound to Detect Optic Disc Swelling

OBJECTIVES Emergency physicians (EPs) frequently evaluate patients at risk for diseases that cause optic disc swelling, and they may encounter conditions that make traditional fundoscopy difficult or impossible. The objective was to assess whether EP-performed point-of-care (POC) ultrasound (US) could accurately assess swelling of the optic disc. METHODS This was a blinded, prospective study using a convenience sample of patients presenting to a neuroophthalmology clinic who were thought to be at risk for conditions associated with optic disc edema. Two EPs performed POC US examinations. Patients then underwent standard clinical assessment by a specialist. RESULTS Fourteen patients were assessed with disc swelling noted on dilated fundoscopic exam in 11 of 28 (39%) eyes. A maximum disc height greater than 0.6 mm as measured by US predicted the presence of optic disc edema noted on fundoscopic exam, with a sensitivity of 82% (95% confidence interval [CI] = 48% to 98%) and a specificity of 76% (95% CI = 50% to 93%). A threshold value of 1.0 mm for disc height yielded a sensitivity of 73% (95% CI = 39% to 94%) and a specificity of 100% (95% CI = 81% to 100%). Measurements of disc height as determined by optical coherence tomography (OCT) exhibited good correlation when compared to US measurements (r = 0.836, p < 0.0001, 95% CI = 0.65 to 0.93). CONCLUSIONS These data suggest that EP-performed POC US can detect clinically apparent optic disc swelling. Because sonography can be performed readily at the bedside, even in cases where fundoscopy is difficult or impossible, this technique may prove to be a valuable tool for the assessment of optic disc swelling in the emergency department (ED).

The Ultrasound-guided “Peripheral IJ”: Internal Jugular Vein Catheterization using a Standard Intravenous Catheter

BACKGROUND Obtaining vascular access is difficult in certain patients. When routine peripheral venous catheterization is not possible, several alternatives may be considered, each with its own strengths and limitations. DISCUSSION We describe a novel technique for establishing vascular access in Emergency Department (ED) patients: the placement of a standard catheter-over-needle device into the internal jugular vein using real-time ultrasound guidance. We present a series of patients for whom this procedure was performed after other attempts at vascular access were unsuccessful. In all cases, the procedure was performed quickly and without complications. CONCLUSION Although further study of this technique is required, we believe this procedure may be a valuable option for ED patients requiring rapid vascular access.

Ultrasound assessment of extraocular movements and pupillary light reflex in ocular trauma

We present the case of a 26-year-old man with significant periorbital trauma after blunt head trauma. Ultrasound techniques for evaluation of extraocular movements and pupillary light reflex are described as a proposed adjunct to physical examination and manual retraction of the eyelids.

Ultrasound assessment of optic disc edema in patients with headache

Point-of-care ocular ultrasonography is emerging as a powerful tool to evaluate emergency department (ED) patients at risk for ophthalmologic and intracranial pathology.We present cases of 3 patients in whom optic disc swelling was identified using ocular ultrasound. Causes for optic disc swelling in our patients included idiopathic intracranial hypertension, secondary syphilis, and malignant hypertension with associated hypertensive retinopathy. Because direct visualization of the optic disc may be challenging in an ED setting, ultrasound examination of the optic disc may represent an important adjunct to fundoscopy when assessing patients with headache or visual complaints.

Gastrointestinal manifestations of hereditary angioedema diagnosed by ultrasound in the emergency department.

Abdominal angioedema is a less recognized type of angioedema, which can occur in patients with hereditary angioedema (HAE). The clinical signs may range from subtle, diffuse abdominal pain and nausea, to overt peritonitis. We describe two cases of abdominal angioedema in patients with known HAE that were diagnosed in the emergency department by point-of-care (POC) ultrasound. In each case, the patient presented with isolated abdominal complaints and no signs of oropharyngeal edema. Findings on POC ultrasound included intraperitoneal free fluid and bowel wall edema. Both patients recovered uneventfully after receiving treatment. Because it can be performed rapidly, requires no ionizing radiation, and can rule out alternative diagnoses, POC ultrasound holds promise as a valuable tool in the evaluation and management of patients with HAE.

Will the real optic nerve sheath please stand up

To the Editor: We applaud Hamilton et al1 for their recent contribution to the study of the retrobulbar optic nerve sheath diameter as a noninvasive surrogate for intracranial pressure. However, although its science appears sound, this article brings to light what we believe is an important limitation to the study of this topic in general: the lack of uniformity in how exactly the optic nerve sheath is identified and measured. In practice, using a high-frequency transducer placed horizontally over a closed eyelid, two distinct structures are visible just posterior to the optic disc. The anterior component of the optic nerve itself is seen as a hypoechoic crescent, which arcs medially and is normally 2.5 to 3.5 mm in width (Figure 1, A). A second thicker, linear or pyramidshaped anechoic column projects directly backward from the posterior surface of the eye to the end of the screen (Figure 1, B). Most recent literature on this topic ignores the presence of the nerve and focuses solely on the latter structure, which is assumed to represent the optic nerve sheath.2–6 Other authors clearly differentiate between the nerve and the dural sheath and include measurements of both structures in their published data.7,8 However, is this latter structure in fact the real optic nerve sheath? Anatomically, the optic nerve and its sheath are not directly orthogonal to the surface of the lid, nor are they rigidly attached to the back of the globe, nor do they take a direct, backward path from the globe to the optic canal. Instead, they take a somewhat meandering, S-shaped, generally medial path through the orbit. Furthermore, the optic nerve sheath tapers to a thinner, not thicker, width as it courses posteriorly. Considering these factors, it is apparent that this sonographic structure could not possibly represent the entirety of the actual optic nerve sheath. It is plausible, however, that it may be an acoustic shadow created by the distal-most edges of the dural sheath of the nerve, a point argued by one investigator.9 If the perineural dural sheath bulges outward due to elevated intracranial pressure, then a measurement of this artifact may be a reliable substitute for the diameter of the sheath itself. However, despite this explanation, some have expressed doubt that this structure is indeed the true optic nerve sheath and have argued that it may represent an unrelated artifact, possibly a shadow cast by the lamina cribrosa or another structure.10,11 In the study by Hamilton et al, the mystery of the identity of the optic nerve sheath deepens. The authors provide an image that appears to display both the optic nerve and the optic nerve sheath as distinct structures, although the shadowlike, linear, hypoechoic stripe (ie, what is typically called the optic nerve sheath) is conspicuously absent. The authors describe the measurement of “a perpendicular intersection from the leading edge to the leading edge of the optic nerve sheath” at specified distances behind the globe. On the published image, the measurement begins in the near field at a subtle, hairlike, gently curving anechoic structure running parallel to the nerve and then traverses what appears to be the perineural subarchnoid space, then the nerve itself, then the subarachnoid space on the far side of the nerve, finally ending at a second thin, sloping anechoic structure, which is labeled the optic nerve sheath. Of interest, this image of the optic nerve sheath is reminiscent of work published in the 1990s by Helmke and Hansen,12 who showed the sonographic appearance of this structure in cadaveric perioptic dural sheaths that had been injected with gelatin. Do Hamilton et al finally provide the correct method for measurement of the optic nerve sheath with point-ofcare sonography? We believe that theirs may be the most convincing pictures of this structure in a living organism, but we would like to see that similar images could be obtained in humans. More importantly, however, we feel that clarification is needed to explain the discrepancy between these images and the appearance of what is typically claimed as the optic nerve sheath. As strong proponents of point-of-care sonography, we are enthusiastic about this application. However, after nearly a decade of clinical experience with the technique, we remain alarmed at the lack of a rigorously defined, easily obtained, and reliable definition of the sonographic optic nerve sheath. LETTER TO THE EDITOR

A randomised experiment comparing low-cost ultrasound gel alternative with commercial gel

Objective Point-of-care ultrasound is a portable, relatively low-cost imaging modality with great potential utility in low-resource settings. However, commercially produced ultrasound gel is often cost-prohibitive and unavailable. We investigated whether images obtained using an alternative cornstarch-based gel would be of comparable quality with those using commercial gel. Methods This was a blinded, randomised, cross-over study comparing commercially produced ultrasound gel with home-made cornstarch-based gel. Ultrasound-trained faculty obtained three video clips with each gel type from patients at one urban ED. The clips were evaluated by a radiologist and an ultrasound-trained emergency physician. Images were assessed in terms of overall adequacy (dichotomous) and quality, resolution and detail using a rating scale (0–10). All sonographers and physicians reviewing the images were blinded to the type of gel used. Results Thirty-four patients were enrolled in the study, producing 204 separate images (102 with each gel). The cornstarch gel clips were deemed accurate in 70.6% (95% CI 63.9% to 76.5%) of the scans, as compared with 65.2% (95% CI 58.4% to 71.4%) of those using commercial gel. There was no difference between the two groups with respect to image detail, resolution or quality. Conclusions Images produced using the cornstarch-based alternative ultrasound gel were of similar quality to those using commercial gel. The low cost and easy preparation of the cornstarch-based gel make it an attractive coupling medium for use in low-resource settings.

Right Lower Quadrant Abdominal Pain: Do Not Forget About Ovarian Torsion on the Computed Tomography Scan

BACKGROUND Abdominal pain is one of the most common chief complaints of patients presenting to emergency departments, and emergency physicians (EPs) often evaluate patients with right lower quadrant abdominal pain. Ovarian torsion is a rare cause of abdominal pain, but early diagnosis is essential for salvage of the affected ovary. The diagnostic study of choice for ovarian torsion is a pelvic ultrasound with color Doppler, but it is important for EPs and radiologists to be aware of findings of ovarian torsion that might appear on computed tomography (CT). CASE REPORT We present a case of a young female with right lower quadrant abdominal pain with CT evidence of ovarian torsion that was not recognized; the patient was discharged and then called back when the study was over-read as concerning for ovarian torsion. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The presence of radiographic findings associated with ovarian torsion on a CT scan should encourage an EP to order a pelvic ultrasound with color Doppler (if available) and obtain an obstetrics/gynecology consult.