A Prospective Evaluation of Ultrasonography for the Diagnosis of Penetrating Torso Injury

Ultrasonography in thoracic and abdominal stab wound injury: results from the FETTHA study

BACKGROUND

While the role of Extended Focused Assessment with Sonography in Trauma (eFAST) is well defined in the management of severe blunt trauma, its performance in injuries caused by stab wounds has been poorly assessed.

METHODS

Prospective single centre study which included all patients with stab wounds to the thorax or abdomen between December 2016 and December 2018. All patients underwent initial investigation with both eFAST and CT scan, except in cases of haemodynamic or respiratory instability, and in cases with a positive diagnosis by eFAST in which case surgery without CT scan was performed.

RESULTS

Of the 200 consecutive patients included, 14 unstable patients underwent surgery immediately after eFAST. In these 14 patients, 9 had cardiac tamponade identified by eFAST and all were confirmed by surgery. In the remaining 186 patients, the median time between eFAST and CT scan was 30 min (IQR 20-49 min). Test characteristics (including 95% CI) for eFAST compared with reference standard of CT scan for detecting pneumothorax were as follows: sensitivity 77% (54%-92%), specificity 93% (90%-97%), positive predictive value (PPV) 60% (49%-83%), negative predictive value (NPV) 97% (93%-99%). Test characteristics (including 95% CI) for eFAST compared with CT scan for detecting haemothorax were as follows: sensitivity 97% (74%-99%), specificity 96% (92%-98%), PPV 83% (63%-93%) and NPV 99% (96%-100%). Finally, test characteristics (including 95% CI) for eFAST compared with CT scan for detecting haemoperitoneum were as follows: sensitivity 75% (35%-97%), specificity 97% (93%-99%), PPV 55% (23%-83%) and NPV 99% (96%-99%).

CONCLUSIONS

In patients admitted with stab wounds to the torso, eFAST was not sensitive enough to diagnose pneumothorax and haemoperitoneum, but performed better in the detection of cardiac tamponade and haemothorax than the other injuries. More robust multicentre studies are needed to better define the role of eFAST in this specific population.

Automated detection and localization of pericardial effusion from point-of-care cardiac ultrasound examination

Focused Assessment with Sonography in Trauma (FAST) exam is the standard of care for pericardial and abdominal free fluid detection in emergency medicine. Despite its life saving potential, FAST is underutilized due to requiring clinicians with appropriate training and practice. To aid ultrasound interpretation, the role of artificial intelligence has been studied, while leaving room for improvement in localization information and computation time. The purpose of this study was to develop and test a deep learning approach to rapidly and accurately identify both the presence and location of pericardial effusion on point-of-care ultrasound (POCUS) exams. Each cardiac POCUS exam is analyzed image-by-image via the state-of-the-art YoloV3 algorithm and pericardial effusion presence is determined from the most confident detection. We evaluate our approach over a dataset of POCUS exams (cardiac component of FAST and ultrasound), comprising 37 cases with pericardial effusion and 39 negative controls. Our algorithm attains 92% specificity and 89% sensitivity in pericardial effusion identification, outperforming existing deep learning approaches, and localizes pericardial effusion by 51% Intersection Over Union with ground-truth annotations. Moreover, image processing demonstrates only 57 ms latency. Experimental results demonstrate the feasibility of rapid and accurate pericardial effusion detection from POCUS exams for physician overread.

A multicenter evaluation of the accuracy of prehospital eFAST by a physician-staffed helicopter emergency medical service

PURPOSE

The purpose of this study is to report the relative accuracy of prehospital extended focused assessment with sonography in trauma (eFAST) examinations performed by HEMS physicians.

METHODS

Trauma patients who received prehospital eFAST by HEMS clinicians between January 2013 and December 2017 were reviewed. The clinician's interpretations of these ultrasounds were compared to gold standard references of CT imaging or operating room findings. The outcomes measured include the calculated accuracy of eFAST for detecting intraperitoneal free fluid (IPFF), pneumothorax, hemothorax, and pericardial fluid compared to available gold standard results.

RESULTS

Of the 411 patients with adequate data for comparison, the median age was 39.5 years with 73% male and 98% sustaining blunt force trauma. For the detection of IPFF, eFAST had a sensitivity of 25% (95% CI 16-36%) and specificity of 96% (95% CI 93-98%). Sensitivities and specificities were calculated for pneumothorax (38% and 96% respectively), hemothorax (17% and 97% respectively), and pericardial effusion (17% and 100% respectively). These results did not change significantly when reassessed with several sensitivity analyses.

CONCLUSION

Prehospital eFAST is reliable for detecting the presence of intraperitoneal free fluid. This finding should inform receiving trauma teams to prepare for early definitive care in these patients. The low sensitivities across all components of the eFAST highlight the importance of cautiously interpreting negative studies while prompting the need for further studies.

TRIAL REGISTRATION

ACTRN12618001973202 (Registered on 06/12/2018).

Deep Learning Assisted Detection of Abdominal Free Fluid in Morison's Pouch During Focused Assessment With Sonography in Trauma

Background: The use of focused assessment with sonography in trauma (FAST) enables clinicians to rapidly screen for injury at the bedsides of patients. Pre-hospital FAST improves diagnostic accuracy and streamlines patient care, leading to dispositions to appropriate treatment centers. In this study, we determine the accuracy of artificial intelligence model-assisted free-fluid detection in FAST examinations, and subsequently establish an automated feedback system, which can help inexperienced sonographers improve their interpretation ability and image acquisition skills.

Methods: This is a single-center study of patients admitted to the emergency room from January 2020 to March 2021. We collected 324 patient records for the training model, 36 patient records for validation, and another 36 patient records for testing. We balanced positive and negative Morison's pouch free-fluid detection groups in a 1:1 ratio. The deep learning (DL) model Residual Networks 50-Version 2 (ResNet50-V2) was used for training and validation.

Results: The accuracy, sensitivity, and specificity of the model performance for ascites prediction were 0.961, 0.976, and 0.947, respectively, in the validation set and 0.967, 0.985, and 0.913, respectively, in the test set. Regarding feedback prediction, the model correctly classified qualified and non-qualified images with an accuracy of 0.941 in both the validation and test sets.

Conclusions: The DL algorithm in ResNet50-V2 is able to detect free fluid in Morison's pouch with high accuracy. The automated feedback and instruction system could help inexperienced sonographers improve their interpretation ability and image acquisition skills.

Narrowed pulse pressure predicts massive transfusion and emergent operative intervention following penetrating trauma

INTRODUCTION

The early identification of hemorrhagic shock may be challenging. The objective of this study was to examine the utility of a narrowed pulse pressure in identifying the need for emergent interventions following penetrating trauma.

METHODS

In this 2.5-year retrospective study of adult patients with a penetrating mechanism, patients with a narrowed pulse pressure (<30 mmHg) were compared to those without. Main outcomes measures were the need for a massive transfusion or emergent operation.

RESULTS

There were 957 patients, of which the majority were male (86%) and 55% presented with gunshot wounds. On multivariate analysis, a narrowed pulse pressure was associated with the need for massive transfusion (OR 3.74, 95% C.I. 1.8-7.7, p = 0.0003) and emergent surgery (OR 1.68, 95% C.I. 1.14-2.48, p = 0.009).

CONCLUSIONS

A narrowed pulse pressure is associated with the presence of hemorrhagic shock and need for emergent interventions among patients with penetrating torso trauma.

Image Segmentation and Machine Learning for Detection of Abdominal Free Fluid in Focused Assessment With Sonography for Trauma Examinations: A Pilot Study

The objective of this pilot study was to test the feasibility of automating the detection of abdominal free fluid in focused assessment with sonography for trauma (FAST) examinations. Perihepatic views from 10 FAST examinations with positive results and 10 FAST examinations with negative results were used. The sensitivity and specificity compared to manual classification by trained physicians was evaluated. The sensitivity and specificity (95% confidence interval) were 100% (69.2%-100%) and 90.0% (55.5%-99.8%), respectively. These findings suggest that computerized detection of free fluid on abdominal ultrasound images may be sensitive and specific enough to aid clinicians in their interpretation of a FAST examination.

Non-operative management of abdominal gunshot wounds

Over the history of surgery, the management of abdominal gunshot wounds in the stable evaluable patient without peritonitis has evolved. While non-operative management has been widely accepted and employed for the management of abdominal stab wounds, recently it has been deemed a safe option for abdominal gunshot wounds as well. Selective non-operative management of penetrating abdominal trauma in the appropriate setting has been shown to decrease the rate of nontherapeutic laparotomy as well as the cost and total length of hospital stay, and potentially decrease short- and long-term morbidity. This review examines the background support for non-operative management of abdominal gunshot wounds while discussing patient evaluation, selection, and clinical management.

Emergency focussed assessment with sonography in trauma (FAST) and haemodynamic stability

Background

Focussed assessment with sonography in trauma (FAST) has assumed a key role in the rapid non-invasive assessment of thoracoabdominal trauma and assists in decreasing disposition time. This study evaluates FAST's efficacy with respect to haemodynamic stability in a South African emergency department (ED).

Methods

Data were collected prospectively by four emergency medicine doctors trained in emergency ultrasonography. FAST scans were performed by one ED doctor and timings, scan result and disposition were recorded. Patient haemodynamic stability was assessed by the emergency doctor performing the scan; subjectively at the time of scanning and objectively using calculation of the shock index. All scan results were subsequently verified by a second ED doctor in a blinded fashion and by CT scanning or operative intervention when clinically indicated.

Results

166 FAST scans were conducted of which 36 (21.7%) were positive. Mean age was 30.6 years (SD 12.8). 74.1% of patients sustained blunt traumatic injury. Doctors’ subjective haemodynamic stability assessments had higher specificity, sensitivity and predictive values than shock index alone. Haemodynamic instability and a positive FAST result were significantly related (p=0.004). Sensitivities and specificities of FAST scans for blunt and penetrating trauma were 93.1% and 100%, and 90.0% and 100%, respectively. Corresponding values for pneumothoraces were 84.6% and 100%.

Discussion

This study showed a valuable role for FAST in all traumas, particularly in haemodynamic compromise. As an addition to the physician's repertoire of bedside assessment tools, it improves diagnostic capabilities in comparison with simple haemodynamic assessments alone.

Immediate thoracotomy for penetrating injuries: ten years' experience at a Dutch level I trauma center

BACKGROUND

An emergency department thoracotomy (EDT) or an emergency thoracotomy (ET) in the operating theater are both beneficial in selected patients following thoracic penetrating injuries. Since outcome-descriptive European studies are lacking, the aim of this retrospective study was to evaluate ten years of experience at a Dutch level I trauma center.

METHOD

Data on patients who underwent an immediate thoracotomy after sustaining a penetrating thoracic injury between October 2000 and January 2011 were collected from the trauma registry and hospital files. Descriptive and univariate analyses were performed.

RESULTS

Among 56 patients, 12 underwent an EDT and 44 an ET. Forty-six patients sustained one or multiple stab wounds, versus ten with one or multiple gunshot wounds. Patients who had undergone an EDT had a lower GCS (p < 0.001), lower pre-hospital RTS and hospital triage RTS (p < 0.001 and p = 0.009, respectively), and a lower SBP (p = 0.038). A witnessed loss of signs of life generally occurred in EDT patients and was accompanied by 100 % mortality. Survival following EDT was 25 %, which was significantly lower than in the ET group (75 %; p = 0.002). Survivors had lower ISS (p = 0.011), lower rates of pre-hospital (p = 0.031) and hospital (p = 0.003) hemodynamic instability, and a lower prevalence of concomitant abdominal injury (p = 0.002).

CONCLUSION

The overall survival rate in our study was 64 %. The outcome of immediate thoracotomy performed in this level I trauma center was similar to those obtained in high-incidence regions like the US and South Africa. This suggests that trauma units where immediate thoracotomies are not part of the daily routine can achieve similar results, if properly trained.

What is the utility of the Focused Assessment with Sonography in Trauma (FAST) exam in penetrating torso trauma?

STUDY OBJECTIVE

A recent Cochrane Review has demonstrated that emergency ultrasonography decreases the amount of computerised tomographic scans in blunt abdominal trauma.13 However, there is no systematic review that has evaluated the utility of the Focused Assessment with Sonography for Trauma(FAST) exam in penetrating torso trauma. We systematically reviewed the medical literature for the utility of the FAST exam to detect free intraperitoneal blood after penetrating torso trauma.

METHODS

We searched PUBMED and EMBASE databases for randomised controlled trials from 1965 through December 2009 using a search strategy derived from the following PICO formulation of our clinical question:

PATIENTS

patients (12+ years) sustaining penetrating trauma to the torso.

INTERVENTION

FAST exam during their initial trauma workup. Comparator: either local wound exploration (LWE),computerised tomography (CT), diagnostic peritoneal lavage (DPL), or laparotomy.

OUTCOME

intraperitoneal and pericardial free fluid. The methodological quality of the studies was assessed.Qualitative methods were used to summarise the study results.

ANALYSIS

Sensitivities and specificities were compared using a Forest Plot (95% CI) calculated by Revman 5 (Review Manager Version 5.0. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration,2008) between the FAST exam and definitive diagnostic modalities such as LWE, CT, DPL, or laporotomy.

RESULTS

We identified eight observational studies (n=565 patients) that met our selection criteria. The prevalence of a positive FAST exam after penetrating trauma was fairly low ranging from 24.2% to 56.3%.The FAST exam for penetrating trauma is a highly specific (94.1–100.0%), but not very sensitive (28.1–100%) diagnostic modality.

CONCLUSION

From the review of the literature, a positive FAST exam has a high incidence of intraabdominal injury and should prompt an exploratory laparotomy. However, a negative initial FAST exam after penetrating trauma should prompt further diagnostic studies such as LWE, CT, DPL, or laparotomy.

Accuracy of conventional imaging of penetrating torso injuries in the trauma resuscitation room

OBJECTIVES

Chest X-ray (CXR), abdominal ultrasound, cardiac ultrasound, and abdominal X-ray are the most frequently used imaging modalities to radiologically evaluate patients with penetrating torso trauma. The aim of this study was to evaluate the accuracy of these imaging modalities.

METHODS

From January 2001 until January 2005, all consecutive patients with penetrating torso injuries presenting at the emergency department of a level 1 trauma center were included. Imaging modalities (chest/abdominal X-ray, abdominal/cardiac ultrasound), were compared retrospectively with a 'gold standard' (i.e. computed tomography or surgery within 2 h after arrival) or outcome of conservative treatment. The accuracy of the imaging modalities was calculated.

RESULTS

Three hundred and eighteen patients were included. On the basis of 299 CXRs, the sensitivity for diagnosing pneumothorax, hemothorax, and subcutaneous emphysema was 71, 63, and 61%, respectively. The sensitivity of abdominal ultrasound (N = 229) to detect free abdominal fluid and/or intra-abdominal injury was 65%. The specificity, positive predictive value, negative predictive value, and accuracy of the two imaging modalities to detect any of the diagnoses mentioned were >or=87%. Cardiac ultrasound (N = 31) did not show any false positive or negative results for detecting cardiac effusion. Pneumoperitoneum was not seen on abdominal X-ray in eight of 11 patients with perforation of a hollow organ.

CONCLUSION

Despite high specificity, positive predictive value, and negative predictive value, a considerable number of lesions remain undetected after CXR and abdominal ultrasound because of moderate-to-inadequate sensitivity. Abdominal X-ray hardly provides additional information. Careful clinical monitoring of patients is mandatory, particularly when computed tomography scan or operative treatment is not indicated.

Minimum cause--maximum effect: the travelogue of a bullet

This case report involves a 57-year-old male, accidentally shot in the chest with a small bore firearm. The bullet entered the left hemithorax, disrupting the left internal mammarian artery. It then penetrated the anterior wall of the right ventricle causing a pericardial tamponade. After leaving the base of the right heart it perforated the diaphragm, the liver, the spleen and the pancreas. Finally, it penetrated the abdominal aorta 3 cm proximally to the coeliac trunk and reached its final position paravertebrally. This case report illustrates that the management of even minimum gunshot wounds requires a maximum variety of surgical skills.

An audit of failed non-operative management of abdominal stab wounds

Selective non-operative management based on clinical assessment has been shown to be a generally safe approach in the management of penetrating stab wounds of the torso. However there will be a subset of patients who fail selective non-operative management. This audit focuses on the failures.

METHODS

The metropolitan surgical service in Pietermaritzburg covers 3 hospitals. At the weekly metropolitan morbidity and mortality meeting all trauma patients are reviewed. All cases of failed selective non-operative management of penetrating abdominal stab wounds are discussed. Failed non-operative management is usually defined as any patient who ultimately requires surgical exploration. We do not subscribe to this as we feel as long as the need for surgical intervention is recognised within a short period of time (<12h) there is little additional morbidity. Recognition of the need for surgical intervention after 12h would be regarded by us as failed non-operative management as we feel the risk of delay associated morbidity begins to increase significantly after this time.

RESULTS

A total of 340 patients with a penetrating anterior abdominal stab wound were managed over the 2 year period under review. A total of 192 (56%) of these patients were subjected to mandatory laparotomy. Of these mandatory laparotomies 98% were positive. The remaining 148 (44%) patients were observed. Of the 148 observed patients a total of 30 (20%) subsequently underwent surgery. A total of 13 patients were only taken to surgery after 12h of observation. In this group of 13 patients the average delay between admission and recognition of injury was 40 h. There were six gastric injuries, one pyloric and pancreatic injury, two gallbladder injuries, one liver, one colon and two small bowel injuries. There were no deaths. 9 patients recovered with no additional morbidity. In the remainder, morbidity included, relaparotomy (1), open abdomen (1), renal failure (1) and prolonged stay in ICU (3).

CONCLUSION

Clinical assessment accurately predicts the need for mandatory laparotomy following a stab wound to the torso. In patients who do not meet the indications for mandatory laparotomy and who are subjected to non-operative management 20% will come to surgery. A subgroup may only be recognised as requiring surgery after more than 12h. These patients are at risk of delay associated morbidity. There are particular anatomical sites and structures which are prone to error.

Comparison of the results of abdominal ultrasonography and exploratory laparotomy in the dog and cat

Results of preoperative ultrasonography and exploratory laparotomy were reviewed retrospectively in a series of 100 small animals to assess the agreement between ultrasonographic and surgical findings and to identify abdominal lesions likely to be missed by ultrasonography. Good agreement occurred between ultrasound reports and surgical reports in 64% of the animals, which supported the use of ultrasonography in potential surgical candidates. A major discrepancy was observed between the ultrasound report and surgical findings in 25% of the animals. Of the various types of pathology encountered in the study, gastrointestinal ulceration or perforation was the most likely lesion to be missed by ultrasonography.

The nonoperative management of penetrating abdominal trauma

The management of penetrating injuries to the abdomen has evolved back to a selective nonoperative approach. Using clinical examination for screening, evaluable patients without hemodynamic instability or peritonitis can safely undergo a trial of nonoperative management. For stab wounds, this involves serial clinical examination with delayed laparoscopic evaluation of the diaphragm for left thoracoabdominal injuries and CT scanning for suspected solid-organ injuries. The same contraindications to nonoperative management apply to gunshot injuries. Gunshot injuries undergoing nonoperative management require detailed trajectory imaging with CT. The presence of peritoneal violation without definite organ injury requires serial clinical examination. Isolated solid-organ injury is not an absolute contraindication to nonoperative management and may benefit from advanced endovascular and percutaneous interventions to facilitate management. Selective nonoperative management of both stab wounds and gunshot injuries is safe and has been shown to decrease the rate of unnecessary laparotomy, length of hospital stay, and management costs.

Ultrasound-diagnosed cardiac tamponade after blunt abdominal trauma—treated with emergent thoracotomy

Ultrasound imaging enhances the physician's ability to evaluate, diagnose, and treat emergency department (ED) patients. Because ultrasound imaging is often time-dependent in the acutely ill or injured patient, the emergency physician is in an ideal position to use this technology. Focused ultrasound examinations provide immediate information and can answer specific questions about the patient's physical condition. We report a case in which blunt trauma to the abdomen and pre-existing pericardial fluid, due to human immunodeficiency virus (HIV), caused pericardial tamponade, diagnosed by bedside ultrasonography, and subsequent cardiac arrest. An ED thoracotomy released this tamponade, and spontaneous cardiac activity returned. The indications for and efficacy of ED thoracotomy have been debated for many years. Multiple studies have shown that patients with isolated penetrating chest trauma have the best outcome and that patients with blunt trauma without signs of life at the scene or in the ED have the poorest. We demonstrate the importance of ultrasound use by emergency physicians to assess trauma patients with pulseless electrical activity and suggest that in specific clinical situations after blunt trauma, an ED thoracotomy can be life saving.

What Does Ultrasonography Miss in Blunt Trauma Patients With A Low Glasgow Coma Score (GCS)?

BACKGROUND

The role of ultrasound (US) as a screening tool for the evaluation of blunt abdominal trauma is still controversial. Determining the types of missed injuries and the accuracy of US in patients with a low GCS will improve the evaluation of these blunt trauma patients.

METHODS

Prospectively collected data from the trauma registry of a Level I trauma center was reviewed.

RESULTS

7,952 patients were included in the study. US examination had an accuracy of 89%, sensitivity of 77%, specificity of 97%, positive predictive value (PPV) of 78%, and negative predictive value (NPV) of 98%. GCS correlated with ISS and base deficit levels. US examination had a significantly lower accuracy in patients with a low GCS and in women.

CONCLUSION

The sensitivity and specificity of US examination is similar in those with normal and low GCS. Therefore ultrasonographic examination may be considered a good screening tool for the evaluation of patients with blunt abdominal trauma, but its accuracy is diminished in patients with a low GCS. Further imaging may be warranted in these patients.