Emergency Department compression ultrasound to diagnose proximal deep vein thrombosis

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Letters to the Editor

added to the scope of practice for paramedics. We are currently using etomidate as our induction agent for all RSI patients, with ongoing sedation by using midazolam and morphine. We appreciate the opportunity to respond to Dr. Morgan’s comments. Christian Sloane, MD Gary M. Vilke, MD, FACEP UCSD Medical Center San Diego, CA PII S0736-4679(01)00413-9

REFERENCES 1. Sloane C, Vilke GM, Chan TC, Hayden SR, Hoyt DB, Rosen R. Rapid sequence intubation in the field versus hospital in trauma patients. J Emeg Med 2000;19:259 – 64.

e Emergency Department Compression Ultrasound to Diagnose Proximal Deep Vein Thrombosis I read with interest the paper by Frazee et al. and I would agree that Emergency Department ultrasound (US) has a potential role in diagnosing proximal lower limb deep vein thrombosis (1). However, I would like to comment on two points. Firstly, this study suffers from some important limitations, namely: small sample size, use of a convenience sample of subjects, and use of comparison views of the contralateral limb that were not protocol driven. These limitations make using the findings of this study as a basis of designing a larger study precarious. Secondly, withholding anticoagulation in patients with a single, complete, negative duplex scan has been shown to be safe (2). The authors mentioned that duplex US is the gold-standard test to diagnose deep vein thrombosis (DVT) in their institution. Do they have any data indicating any difference among Emergency Physician (EP) sonographers with regard to achieving competence in compression US compared to duplex US? If there is no significant difference in the learning curves of the two sonographic methods, considering the limitations of the study, future research should concentrate on Emergency Physician sonographers achieving competency in duplex US rather than compression US. Abel Wakai, MD Department of Emergency Medicine Beaumont Hospital Dublin, Republic of Ireland PII S0736-4679(01)00414-0

REFERENCES 1. Frazee BW, Snoey ER, Levitt A. Emergency department compression ultrasound to diagnose proximal deep vein thrombosis. J Emerg Med 2001;20:107–11. 2. Wolf B, Nichols DM, Duncan JL. Safety of a single duplex scan to exclude deep venous thrombosis. Br J Surg 2000;87:1525– 8.

e Response to Letter to the Editor: We appreciate Dr. Wakai’s interest in our report describing use of Emergency Department limited compression ultrasound (US) to investigate possible deep vein thrombosis (DVT). We agree that the study suffered from a number of methodologic flaws, such as lack of a standardized scanning protocol, as well as from small sample size that resulted in large confidence intervals around test performance characteristics. However, rather than representing a “precarious” basis for future study design, we would hope that the flaws evident in a small, preliminary study such as ours will help to shape and focus the design of a larger, more definitive study. Indeed, a multicenter study of Emergency Department US for diagnosis of DVT is currently being planned as part of the Sonographic Outcomes Assessment Program (SOAP). With regard to the important issue of limited compression US compared to a full duplex US examination for diagnosis of DVT, we wish to make the following points. (a) Withholding anticoagulation after negative limited compression US has been shown to be safe in a number of studies (1–3). Indeed, the first large, prospective study of US to diagnose proximal DVT in outpatients, demonstrating 100% sensitivity compared to venography, involved a limited compression US protocol essentially identical to that in our study (4). (b) Duplex US involves multiple Doppler assessments of venous flow in addition to simple vein compression using Bmode. It seems intuitive that a more complicated duplex study would require significantly more training to gain proficiency. (c) Certainly, limited compression US can be done more rapidly than duplex, and may be better suited for the Emergency Medicine environment. Support for this assertion comes from the study by Blaivis et al., in which compression US by Emergency Physicians (EPs) (using B-mode plus color-flow scanning) took a median of 3.5 min to perform, whereas in the study by Jolly et al., a full duplex examination by EPs took “as long as 30 min” (5,6). (d) We are aware of only three studies directly comparing accuracy of compression US to duplex for diagnosis of DVT; all showed no difference in diagnostic performance (7–9). (e) Two recent reviews of the diagnostic approach to DVT contend that compression US, not duplex, is the objective test of choice for diagnosis of proximal DVT (10,11). The upcoming,