Article, Cardiology

Compression with a pocket-sized ultrasound device to diagnose proximal deep vein thrombosis

a b s t r a c t

Introduction: Compression ultrasonography (CUS) is a validated technique for the diagnosis of Deep venous thrombosis , but has never been studied with pocket-sized Ultrasound device (PUD). The main objective of this study was to assess the diagnostic performance of CUS made by emergency physicians (EPs) using a PUD. Materials: This was a prospective, diagnostic test assessment, single-center study. Patients underwent VCU per- formed by a trained EP with PUD (CUS-PUD) for searching proximal DVT (PDVT) and were then seen by an expert vascular physician who blindly performed a duplex venous ultrasound, which was the criterion standard. CUS- PUD’s diagnostic performance was evaluated by sensitivity (Se), specificity (Sp), and positive and negative pre- dictive values (PPV and NPV).

Results: The sample included 57 patients of whom 56 were analyzed. Eleven (20%) PDVT were diagnosed with CUS-PUD: 7 (64%) femoral and 4 (36%) popliteal. The CUS-PUD’s Se was 100% [72%; 100%], Sp 100% [92%;

100%]. The PPV was 100% [74%; 100%], and the NPV was 100% [90%; 100%].

Conclusion: CUS-PUD performed with a pocket-sized ultrasound appears to be feasible in emergency practice for the diagnosis of proximal DVT. A study with a larger sample size will have to describe the accuracy.

(C) 2018

Introduction

Suspected Deep vein thrombosis is a common presentation seen in the Emergency Department (ED) [1]. Because it can result in pul- monary embolism [1,2], suspected DVT requires a confirmatory test in order to start early treatment. Venous duplex ultrasonography (VDUS) is the criterion standard for diagnosing DVT with a sensitivity (Se) of 96% and a specificity (Sp) from 98 to 100% [3]. This test is subject to ma- terial and human constraints (e.g., availability of certified practitioners). When it is impossible to rule out DVT, sometimes anticoagulation treat- ment is recommended [4], thus exposing patients to its complications, whereas only 23% of them really have DVT [1,3].

* Corresponding author.

E-mail addresses: [email protected], (S. Pujol), [email protected], (J. Laurent), [email protected], (T. Markarian), [email protected], (P.-G. Claret), [email protected],

(J.Y. Lefrant), [email protected], (C. Roger), [email protected], (L. Muller), [email protected], (J.E. de La Coussaye), [email protected], (A. Perez-Martin), [email protected]. (X. Bobbia).

Compression ultrasonography (CUS) performed by an emergency physician is one of the applications of point-of-care ultrasonogra- phy (POCUS) [5,6]. It is currently recommended for diagnosis of proxi- mal DVT (PDVT) [7]. CUS consists of compressing the common femoral vein and popliteal vein with the probe [8]. Pomero et al.’s meta-analysis [3] found CUS Se from 70 to 100% (97.6% if considering only high-quality studies) and Sp from 78 to 100% (96.8% in high- quality studies). A recent study confirmed that emergency physicians can obtain a level of competence equivalent to that of radiologists mak- ing compression ultrasonography [9]. CUS by EP can be useful in an overcrowded ED due to Time Savings and avoiding risks of a non- indicated anticoagulation therapy. CUS seems to have a fast learning curve [10]. Lastly, guidelines for DVT diagnosis give three elements to indicate VDUS and anticoagulation: the clinical assessment of pretest probability, D-dimer, and CUS [7].

CUS with portable vascular ultrasonography is pertinent [11]: Se 100% [92%; 100%], Sp 99% [96%; 100%]. The miniaturization of ultra- sound devices represents major progress allowing the large-scale devel- opment of POCUS [12]. pocket-sized ultrasound devices (PUD) seem to be particularly adapted at POCUS. Numerous publications have already

https://doi.org/10.1016/j.ajem.2018.03.076

0735-6757/(C) 2018

S. Pujol et al. / American Journal of Emergency Medicine 36 (2018) 12621264 1263

demonstrated their potential use in many emergency ultrasound appli- cations [13-15].

The main objective of our study was to assess the diagnostic perfor- mance of CUS made by an EP with a PUD (CUS-PUD) in suspected cases of PDVT (excluding patients with prior history of DVT).

Materials and method

Materials

This prospective, diagnostic test assessment, single-center study was conducted from April 2015-February 2017. The study population com- prised patients attending the ED of University Hospital of Nimes. The study protocol was approved by the Committee on Human Research South Mediterranean III (CPP-2014.07.18) and written informed con- sent was obtained from all patients. The protocol was registered at ClinicalTrials.gov (NCT02262494). Patients were included if they were admitted to the ED for suspicion of a first DVT. All included patients were older than 18 years, had health insurance, and were not participat- ing in another study. Patients were not included if they had a prior his- tory of Venous thromboembolic disease.

Aims

The primary objective of our study was to determinate diagnostic performance of CUS-PUD in cases of suspected PDVT (except patients with prior history of DVT). Se, Sp, and predictive values of CUS-PUD were calculated. The gold standard was VDUS made by a vascular certi- fied practitioner. Secondary aim was to compare in those patients, diag- nostic performance of CUS-PUD depending on clinical assessment of pretest probability (determined by Wells’ Criteria).

Measurements

CUS-PUD observation was made by an experienced EP (defined as owning an ultrasonography university diploma associated with daily practice) with PDU (V-Scan Dualprobe(C), GE Healthcare, Milwaukee, Wisconsin, USA). CUS-PUD tests the ability of the ultrasound probe to compress the common femoral vein then popliteal vein on the lower- limb studied. The CUS-PUD was performed as follows (first in femoral then in popliteal): if a Venous thrombus was visualized or if the vein was incompressible, then the exam was positive and stopped. If there was no thrombus visualized and if the femoral then popliteal vein were compressible, then the exam was negative. After CUS-PUD, the pa- tient had a VDUS. This exam was performed by physicians blinded to the result from CUS-PUD.

Results

Participants

Between April 2015 and February 2017, of 232 patients eligible for recruitment 57 were included (25%). One patient was excluded from the study because he could not receive VDUS. Five EPs participated in the recruitment. Of the 56 patients analyzed, 33 (59%) were women of median age 73 [59-84] years and of BMI 26 [22-30] kg/m2. The base- line characteristics of the 56 participants (Wells’ score and items, clini- cal probability, anticoagulation) are shown in Table 1. Sixteen (29%) DVTs were diagnosed by VDUS: 11 (69%) proximal and 5 (31%) distal.

Primary outcome diagnostic performance of CUS-PUD made with PSU

Eleven (20%) proximal DVT were diagnosed by CUS-PUD: 7 (64%) femoral and 4 (36%) popliteal. Sensitivity and specificity of CUS-PUD were 100% [72%; 100%] and 100% [92%; 100%], respectively. PPV was 100% [74%; 100%] and NPV was 100% [90%; 100%]. As a result of sensitiv- ity and specificity values of 100%, the likelihood ratios were not calcula- ble. No comparative studies based on the clinical assessment of pretest probability could be done due to the CUS-PUD’s sensitivity and specific- ity of 100%.

Discussion

Main results

Our main result was that CUS-PUD seems to be feasible for the diag- nosis of PDVT. With a small sample size, our study showed a sensitivity of 100% [72%; 100%], a specificity of 100% [92%; 100%], a PPV of 100%

[74%; 100%], and an NPV of 100% [90%; 100%]. The lower limits of the

confidence intervals do not allow to correctly judge the accuracy. Diag- nostic studies made with conventional ultrasonography [1,3,4,12,16] showed sensitivities and specificities of 95-98% and 96-97%, respec- tively [3]. Previous studies analyzed samples of 148 patients on average, with low-trained CUS-PUD operators (1 h of exam reading, 1-3 h of training). There is only Magazzini’s study [16] with a sample size of 399 patients that had two very well-trained operators: 30-hour course, 6 h of lectures, and 24 h of training under supervision. In this study, CUS- PUD had a sensitivity of 100% and a specificity of 98%. Previous studies included more operators, especially Crisp’s investigation (48 operators

Table 1

Patients’ characteristics. Data are expressed in median [25th percentile; 75th percentile] or n (%).

Patients N= 56

2.4. Sample size

Two hundred and thirty-six patients were required to demonstrate a sensitivity of 95% with a confidence interval of 95% and a lower limit N0.85. Due to difficulty with recruitment, this study was terminated after enrolling 56 patients.

2.5. Statistical analysis

Quantitative data are expressed as the median with 25th and 75th percentiles ([25th percentile; 75th percentile]). Qualitative variables are expressed as frequency with percentages. Diagnostic performance of CUS-PUD (Se, Sp, PPV, and NPV) was estimated with confidence in- tervals of 95%. The significance level was set at 5% for all tests used. Sta- tistical analysis was performed under R 3.3.3 (2017, R Foundation for Statistical Computing, Vienna, Austria).

Wells’ criteria

Localized tenderness along deep Venous system 37 (66%)

Swelling of entire leg 34 (61%)

Unilateral Pitting edema 25 (45%)

Calf swelling N3 cm compared with asymptomatic calf 20 (36%) Paralysis, paresis or recent cast immobilization of lower extremity 18 (32%) Recent bedridden N3 days 14 (25%)

alternative diagnosis as likely 8 (14%)

Active cancer 7 (12%)

Swollen unilateral superficial veins (non-varicose) 5 (9%)

Wells’ score 2 [1; 3]

Clinical pre-test probability

Low 5 (9%)

Moderate 27 (48%)

High 24 (43%)

Anticoagulation 8 (14%)

Curative 5 (63%)

Preventive 3 (37%)

Oral 5 (63%)

Intravenous 3 (37%)

1264 S. Pujol et al. / American Journal of Emergency Medicine 36 (2018) 12621264

with 10 min of training for CUS-PUD) that found a sensitivity of 100% and a specificity of 99%. Our results are better. Our sample is smaller and baseline performances are inside the confidence intervals of 95%. Moreover, in our study, the prevalence of DVT was similar to the litera- ture (29% vs. 24%), with Pomero’s meta-analysis [3] finding very vari- able prevalence ranging from 7%-43%. The pretest clinical probabilities of our patients were essentially average too high. These results confirm the representativeness of our sample and allow us to generalize our results.

Originality of the study

To our knowledge, the validity of compression ultrasonography for diagnosing PDVT performed using a pocket-sized ultrasonography has never been studied. In our study, CUS-PUD for detecting PDVT had the same results as VDUS (Se, Sp, PPV, and NPV were 100%). If the small sample size did not allow a lower bound on the 95% confidence inter- vals, we showed CUS-PUD seems to be feasible. A study with a larger sample size will have to describe the accuracy.

Limits

The main limitations of this study are the small sample size and slow recruitment, which was mainly due to material constraints and forced the study’s early termination. Finally, the small number of EPs who per- formed CUS-PUD exposes us to a classification bias because these physi- cians were probably more invested and trained. Second, the limited number of operators, particularly trained in this POCUS application may also explain those perfect results.

Conclusion

CUS is a technique that is reliable and achievable in current ED prac- tice for the diagnosis of PDVT. CUS-PUD performed with a pocket-sized ultrasound appears to be feasible in emergency practice for the diagno- sis of proximal DVT. A study with a larger sample size will have to de- scribe the accuracy.

Acknowledgments

The authors acknowledge all the emergency physicians who re- cruited the patients as well as Audrey Ayral, Sophie Lloret and Loubna El Otmani for data collection.

Competing interests

XB declares a competing interest as an ultrasound teacher for GE (GE MEDICAL SYSTEMS ULTRASOUND) customers. The other authors state they have no competing interests.

References

  1. Frazee BW, Snoey ER, Levitt A. Emergency department Compression ultrasound to diagnose proximal deep vein thrombosis. J Emerg Med 2001 Feb;20(2):107-12.
  2. Le Gal G, Righini M, Sanchez O, Roy PM, Baba-Ahmed M, Perrier A, et al. A positive compression ultrasonography of the lower limb veins is highly predictive of pulmo- nary embolism on computed tomography in suspected patients. Thromb Haemost 2006 Jun;95(6):963-6.
  3. Pomero F, Dentali F, Borretta V, Bonzini M, Melchio R, Douketis JD, et al. Accuracy of emergency physician-performed ultrasonography in the diagnosis of deep-vein thrombosis: a systematic review and meta-analysis. Thromb Haemost 2013 Jan; 109(1):137-45.
  4. Kearon C, Akl EA, Comerota AJ, Prandoni P, Bounameaux H, Goldhaber SZ, et al. An- tithrombotic therapy for VTE disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012 Feb;141(2 Suppl):e419S-94S.
  5. Ultrasound Guidelines. Emergency, point-of-care and clinical ultrasound guidelines in medicine. Ann Emerg Med 2017 May;69(5):e27-54.
  6. Moore CL, Copel JA. Point-of-care ultrasonography. N Engl J Med 2011 Feb 24;364 (8):749-57.
  7. Bates SM, Jaeschke R, Stevens SM, Goodacre S, Wells PS, Stevenson MD, et al. Diag- nosis of DVT: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012 Feb;141(2 Suppl):e351S-418S.
  8. Lensing AW, Prandoni P, Brandjes D, Huisman PM, Vigo M, Tomasella G, et al. Detec- tion of deep-vein thrombosis by real-time B-mode ultrasonography. N Engl J Med 1989 Feb 9;320(6):342-5.
  9. Pedraza Garcia J, Valle Alonso J, Ceballos Garcia P, Rico Rodriguez F, Aguayo Lopez MA, Munoz-Villanueva MDC. Comparison of the accuracy of emergency department-performed point-of-care-ultrasound (POCUS) in the diagnosis of lower-extremity deep vein thrombosis. J Emerg Med 2018 Jan;3.
  10. Jang T, Docherty M, Aubin C, Polites G. Resident-performed compression ultrasonog- raphy for the detection of proximal deep vein thrombosis: fast and accurate. Acad Emerg Med 2004 Mar;11(3):319-22.
  11. Crisp JG, Lovato LM, Jang TB. Compression ultrasonography of the lower extremity with portable vascular ultrasonography can accurately detect deep venous throm- bosis in the emergency department. Ann Emerg Med 2010 Dec;56(6):601-10.
  12. Solomon SD, Saldana F. Point-of-care ultrasound in medical education–stop listen- ing and look. N Engl J Med 2014 Mar 20;370(12):1083-5.
  13. Biais M, Carrie C, Delaunay F, Morel N, Revel P, Janvier G. Evaluation of a new pocket echoscopic device for focused cardiac ultrasonography in an emergency setting. Crit Care 2012;16(3):R82.
  14. Dijos M, Pucheux Y, Lafitte M, Reant P, Prevot A, Mignot A, et al. Fast track echo of Abdominal aortic aneurysm using a real pocket-ultrasound device at bedside. Echo- cardiography 2012 Mar;29(3):285-90.
  15. Bobbia X, Pradeilles C, Claret PG, Soullier C, Wagner P, Bodin Y, et al. Does physician experience influence the interpretability of focused echocardiography images per- formed by a pocket device? Scand J Trauma Resusc Emerg Med 2015 Jul 7;23:52.
  16. Magazzini S, Vanni S, Toccafondi S, Paladini B, Zanobetti M, Giannazzo G, et al. Du- plex ultrasound in the emergency department for the diagnostic management of clinically suspected deep vein thrombosis. Acad Emerg Med 2007 Mar;14(3): 216-20.

Leave a Reply

Your email address will not be published. Required fields are marked *