Article, Emergency Medicine

The value of point-of-care ultrasound for detecting nail bed injury in ED

a b s t r a c t

Objective: The aim of this study is to detect the value of Point-of-care ultrasound for diagnosing a nail bed injury and fracture of distal phalanx in patients presenting with distal finger trauma to the emergency department (ED).

Methods: Patients, 18 to 65 years old, presenting with a blunt trauma of distal finger and diagnosed with subungual hematoma were eligible for the study. Subungual hematoma extending over more than 50%, fracture of distal phalanx, and disruption of periungual tissue or nail integrity were accepted as the indications for nail bed inspection. All the study patients underwent POCUS to detect the existence of a distal phalanx fracture or nail bed injury. X-ray was also obtained from all the patients.

Results: Nail bed was visualized in 45 patients. Squeezing and Crush injury were the most reported trauma mechanism in study patients (66.7%). The sensitivity and specificity of POCUS in detecting nail bed injury were 93.4% (95% CI, 80%-99%) and 100% (95% CI, 74%-100%), respectively. The sensitivity was 100% (95% CI, 79%-100%), and specificity was 98.4% (95% CI, 91%-100%) for distal phalanx fracture.

Conclusion: Point-of-care ultrasound is a promising tool in detecting the nail bed injury and distal Phalanx fractures in patients presented with distal finger trauma. Further studies with bigger sample size are needed to reveal the Diagnostic ability of POCUS before using it regularly in the ED.

(C) 2016

Introduction

Nails are substantial part of fingers that are improving hand function by aiding to grasp objects and tactile sensation. Besides its cosmetic sig- nificance, they are also of importance for fingertip stability and gripping function of 2 fingers [1].

Injuries to the nail are usually caused by direct forces toward the dorsum of the fingertip leading to crushing or breaking of the nail. Subungual hematoma is the collection of the blood between the nail bed and the nail secondary to the trauma over the nail. A wide range of injuries such as punctate injuries, laceration, and contusion of the nail bed may lead to collection of the blood over the nail bed. Various type of injuries of nail bed differ in treatment options where a laceration requires a repairment but a punctuate injury not.

* Corresponding author.

E-mail addresses: [email protected] (F. Gungor), [email protected] (K.C. Akyol), [email protected], [email protected] (C. Eken), [email protected] (M. Kesapli), [email protected] (I. Beydilli), [email protected] (M. Akcimen).

Subungual hematoma, fractures, and nail bed injuries may accom- pany nail injuries. Subungual hematoma, which is one of the most com- mon nail injuries, increases the risk of pain and infection [2]. Fracture may accompany subungual hematoma in many patients [3]. Subungual hematoma that is extending over more than 50%, fracture of distal pha- lanx, and corruption of periungual tissue and nail are commonly related to nail bed injuries [4-6].

The current recommended treatment to repair nail bed injuries re- quires visual inspection of the injury [7]. Inspection of a nail bed can be achieved by lifting the nail up; however, this is an invasive procedure with the risk of complications, such as a germinal matrix injury and pain. An injury to the germinal matrix is of particular concern for repair [6,7]. Any tissue with contusion should be repaired by careful debride- ment, and also, grafts may be used for tissue defects. [1,8]. Nevertheless, there are conservative approaches for nail bed injuries if the nail and the surrounding nail margins are intact.

Point-of-care ultrasound has been gaining a wide range of indication in emergency department (ED) for detecting extremity injuries such as Shoulder dislocation, tendon injuries, and metacarpal fractures [9-11]. It is an easy tool to learn with the ease of being per- formed bedside without radiation exposure.

http://dx.doi.org/10.1016/j.ajem.2016.06.067

0735-6757/(C) 2016

Fig. 1. Normal ultrasound view of nail, nail bed, and distal phalanx. Arrow indicates the nail; the star shows nail bed; and the arrow head, distal phalanx.

The aim of this study is to detect the diagnostic accuracy of POCUS for diagnosing a nail bed injury and fracture of distal phalanx in patients presented with distal finger trauma to the ED.

Materials and methods

Study design and setting

This prospective cross-sectional pilot study with a convenience sampling was conducted between November 2013 and May 2014 in an ED of a tertiary care hospital with an annual census of 200 000 patients. Antalya Research and Training Hospital Ethical Com- mittee approved the study, and written inform consent was obtained from all the study patients.

Selection of participants

Patients between 18 and 65 years old presented with blunt distal finger trauma and diagnosed with subungual hematoma were ac- cepted as eligible for the study. Patients with subungual hematoma were screened for a hematoma extending over more than 50% of the nail bed, fracture of distal phalanx, and disruption of periungual tissue or nail integrity. If the patient had 1 of these 3 aforementioned pathologies, the patient was accepted as having an indication for a nail bed inspection and enrolled to the study. Patients refusing to give informed consent and patients with a subungual hematoma of less than 50% and no existing injury depicted above were excluded from the study.

Patients eligible for the study were initially evaluated by a resi- dent who also recorded the injury mechanism and physical

Fig. 2. A, The arrow above shows the nail bed injury and arrow below displaying the ultrasound view. hematoma formation may also be seen over the nail bed injury. B, The arrow above shows the nail bed injury of the patient. The arrows below display the phalanx fracture and nail bed injury.

Fig. 3. Patient flow chart.

examination findings including the extension of the subungual he- matoma and the integrity of periungual tissue and nail into the study form. Patients enrolled to the study had a POCUS evaluation by the attending physician.

Study procedure

Five ultrasound certificated attending physicians who had already been performing POCUS in the ED regularly participated in the study to conduct the ultrasound of nail bed and distal phalanx. They had also been trained by a 1-hour theoretical and 2-hour practical lecture on the fingertip and nail bed anatomy and related injuries before the study. One among these5 certificated physicians who was also a certificated ul- trasound trainer conducted the POCUS training over nail bed. All the pa- tients enrolled to the study (n = 45) had POCUS to detect the existence of a distal phalanx fracture or nail bed injury. One of these 5 physicians per- formed the POCUS for each study patient. Only the patients enrolled to the study (n = 45) had nail bed inspection by lifting the nail up. The nail bed injury was defined as a laceration or contusion in the nail bed.

All the patients who were eligible for the study (n = 75) obtained an x-ray before being enrolled to the study. X-rays were reviewed both by the initial physician (resident) and another attending physician, and they were also blinded to the POCUS findings.

All the findings after the POCUS and x-ray were recorded. Treating

physicians of the study patients were also different and changing shift by shift.

Methods of measurements

ESAOTE, MYLAB CLASS-C ultrasound machined with high-frequency LA 533/3.0 to 13.0 MHz linear transducer, was used for the study. Distal phalanx was evaluated from palmar and dorsal sides in both longitudi- nal and perpendicular views to detect a fracture. A disruption in cortical integrity was accepted as fracture. Nail bed evaluation was carried out from the dorsal side of the finger in longitudinal and perpendicular po- sitions. Fig. 1 shows a normal and intact nail bed. Any disruption of the nail bed integrity in the ultrasound view was accepted as a nail bed in- jury. This is usually accompanied a subungual hematoma of various size as displayed in Fig. 2. If the quality of the nail bed view is not sufficient, the screener decided to use the water bath technique which was

Table 1

Demographic features of study patients

Variable n (%)

Age (mean +- SD) Sex

32 +- 9.1

Male

35 (77)

Destruction of periungual tissue

21 (46.7)

Destruction of nail integrity

3 (6.7)

Fracture in x-ray

16 (29)

Nail bed injury

33 (73.3)

Table 2

Diagnostic performance of POCUS for nail bed injury and fracture

Variable

Sensitivity (95% CI)

Specificity (95% CI)

PLR (95% CI)

NLR (95% CI)

Nail bed injury

93.9 (80-99)

100 (74-100)

Null

0.06 (0.02-0.23)

Fracture

100 (79-100)

98.4 (91-100)

59 (8-412)

Null

Abbreviations: PLR, positive likelihood ratio; NLR, negative likelihood ratio.

performed by placing a 100-mL normal saline bag over the nail to form an acoustic window.

Fig. 1 shows a normal nail bed and a distal phalanx evaluation.

Fig. 2A and B shows a nail bed injury and a distal phalanx fracture.

Primary outcome

The primary outcome of the study was to evaluate the diagnostic value of POCUS in detecting a nail bed injury defined above.

Statistical analysis

The study data was analyzed by MedCalc Software. Numerical data were expressed as mean +- SD; and the frequent data, as rate. The value of POCUS in detecting nail bed injury and distal phalanx fracture was presented by sensitivity, specificity, and likelihood ratios, which are also displayed by using 95% confidence interval (CI).

Results

A total of 75 patients presented with subungual hematoma to the ED. The most common type of trauma was squeezing and crush injury in 50 patients (66.7%), a falling object in 18 patients (24%), and direct impact in 7 patients (9.3%).

Forty-five patients fulfilled the inclusion criteria and composed the study population. Fig. 3 depicts the flow of the study patients. The de- mographic features of the study patients are displayed in Table 1.

Thirty-three patients (73.3%) were established to have a nail bed in- jury. Point-of-care ultrasound missed 2 cases with nail bed injury (sen- sitivity, 93.4%; 95% CI, 80%-99%) but with no false-positive results (specificity, 100%; 95% CI, 74%-100%) (Table 2).

Point-of-care ultrasound diagnosed 1 patient as to have a fracture in-

correctly (specificity, 98.4%; 95% CI, 91%-100%) but with no false- negative result (sensitivity, 100%; 95% CI, 79%-100%) (Table 2).

Discussion

This study showed that POCUS is particularly a specific but also a sensitive tool for diagnosing nail bed injuries. Furthermore, it is either a sensitive or specific tool in detecting distal phalanx fractures. Most of nail injuries are crush in origin and particularly seen in young adults and children [12,13]. Doraiswamy and Baig [14] studied the children with isolated Finger injuries ignoring the existence of metacarpal trau- ma and reported the fracture rate as 26%. It is found to be 21% in the present study. It might be related to different study samples that the present study included only adult patients with distal finger injuries. Displaced fractures may require surgical fixation, but a splint should be sufficient for fractures without displacement. Furthermore, nail bed injuries with fractures should be considered as Open fractures, which re- quire antibiotic therapy [15].

Only 2 patients in the present study required surgical fixation, whereas the remaining was treated by splint and antibiotherapy.

Nail beds should be cured without the scar tissue formation for good cosmetic and functional outcomes. Scar tissue formation in sterile ma- trix may lead to separation and splitting of the nail. Furthermore, an in- jury with scar tissue in the germinal matrix may hinder the growth of the nail. So, POCUS as a noninvasive and bedside tool can select suitable

patients who really need nail bed inspection and avoid unnecessary in- vasive procedures.

The treatment of subungual hematomas is controversial. Some au- thors offer to inspect the nail bed by lifting the nail up in all patients [5]. However, lifting up the nail is an invasive procedure, particularly in the existence of an intact nail bed. The germinal matrix may also be injured during the procedure, and oligoanalgesia may cause pain. So, noninvasive diagnostic tools should be needed for reducing the unnec- essary invasive procedures for these patients. X-rays are the standard diagnostic tools for detecting fractures in EDs. However, the challenges of not being applicable at bedside, radiation exposure, and not being able to provide information about the nail bed injuries are of concern for taking an x-ray. Point-of-care ultrasound has been used for orthope- dic injuries in ED for a while, which may also shorten the evaluation and treatment time [16].

Using POCUS should make sense in a wide range of orthopedic inju- ries such as muscle and tendon [16-18]. It is also specific in revealing bone fractures such as ribs, femur, clavicle, metacarpals, phalanx, and others [11,19-21]. Similar to the current medical literature, the present study also showed that POCUS may be a robust tool either for excluding or revealing phalanx fracture with a sensitive of 100% and 98% of spec- ificity. Although there were no false-negative results, POCUS diagnosed 1 patient as having a fracture incorrectly. However, nondisplaced frac- tures, sophisticated anatomical locations such as wrist, and fracture in childhood may not be detected by plain radiograph. Point-of-care ultra- sound might be used in these kind fractures [20-23]. Furthermore, x-ray might have been false negative rather than the POCUS in this case.

Despite the existence of a substantial amount of data relevant to the use of POCUS in various types of fractures, there are little data regarding POCUS for nail bed injuries except a single case report [24]. Soyuncu and Bektas [24] reported a case of crush injury resulted with subungual he- matoma and nail bed injury diagnosed by POCUS.

The present study showed that there may be false-negative results in detecting a nail bed injury (2 patients in the present study), but the specificity is much better (100%).

Limitations

The present study has several limitations. It has a small sample size related to large CIs. We used a convenience sampling that only the eligi- ble patients were included into the study during the shifts when the 5 attending physicians trained for the study worked in the ED. Ultrasound is a user-dependent diagnostic tool, which may lead to diverse results in various studies. However, experience on nail bed ultrasound might be related to better sensitivity and specificity. There were only 5 screeners in the present study, which limits the generalizability of the results when considering ultrasound is a user-dependent diagnostic tool. Fur- thermore, the data of the remaining 30 patients excluded from the study might change the sensitivity and specificity if their nail was inspected.

Conclusion

Point-of-care ultrasound is a specific tool in detecting a nail bed inju- ry and both a sensitive and specific tool for distal phalanx fractures in patients presented with distal finger trauma. Further studies are needed with robust findings to reveal the exact value of POCUS on nail bed injuries.

Acknowledgment

The authors declared there is no conflict of interest.

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