Diagnostic performance of prehospital ultrasound diagnosis for traumatic pneumothorax by a UK Helicopter Emergency Medical Service

[Recommendations for Education in Sonography in Prehospital Emergency Medicine (pPOCUS): Consensus paper of DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI and DGIIN]

Point-of-care sonography is a precondition in acute and emergency medicine for the diagnosis and initiation of therapy for critically ill and injured patients. While emergency sonography is a mandatory part of the training for clinical acute and emergency medicine, it is not everywhere required for prehospital emergency medicine. Although some medical societies in Germany have already established their own learning concepts for emergency ultrasound, a uniform national training concept for the use of emergency sonography in the out-of-hospital setting is still lacking. Experts of several professional medical societies have therefore joined forces and developed a structured training concept for emergency sonography in the prehospital setting. The consensus paper serves as quality assurance in prehospital emergency sonography.

[Recommendations for Education in Sonography in Prehospital Emergency Medicine (pPOCUS): Consensus paper of DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI and DGIIN]

Point-of-care sonography is a precondition in acute and emergency medicine for the diagnosis and initiation of therapy for critically ill and injured patients. While emergency sonography is a mandatory part of the training for clinical acute and emergency medicine, it is not everywhere required for prehospital emergency medicine. Although some medical societies in Germany have already established their own learning concepts for emergency ultrasound, a uniform national training concept for the use of emergency sonography in the out-of-hospital setting is still lacking. Experts of several professional medical societies have therefore joined forces and developed a structured training concept for emergency sonography in the prehospital setting. The consensus paper serves as quality assurance in prehospital emergency sonography.

Empfehlungen zur Sonografieausbildung in der prähospitalen Notfallmedizin (pPOCUS): Konsensuspapier von DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI und DGIIN

Die Point-of-Care-Sonografie ist in der Akut- und Notfallmedizin ein fester Bestandteil der Diagnostik und Therapieeinleitung von kritisch kranken und verletzten Patienten. Während die Notfallsonografie im Rahmen der Zusatzweiterbildung für klinische Akut- und Notfallmedizin vorausgesetzt wird, wird diese für die prähospitale Notfallmedizin lediglich im (Muster-)Kursbuch Allgemeine und spezielle Notfallbehandlung als Weiterbildungsinhalt definiert. Obwohl einige Fachgesellschaften in Deutschland bereits eigene Lernkonzepte für die Notfallsonografie etabliert haben, fehlt bis dato ein einheitliches nationales Ausbildungskonzept für den Einsatz der Notfallsonografie im prähospitalem Umfeld. Experten mehrerer Fachgesellschaften haben daher als Empfehlung für die notfallmedizinische Weiterbildung ein Kurskonzept für die spezielle Ausbildung in der prähospitalen Notfallsonografie erarbeitet, welche gleichermaßen zu deren Qualitätssicherung beitragen soll.

Prehospital Ultrasound: A Narrative Review

Background: Point-of-care ultrasound is rapidly becoming more prevalent in the prehospital environment. Though considered a relatively new intervention in this setting, there is growing literature that aims to explore the use of prehospital ultrasound by EMS personnel.Methods: To better understand and report the state of the science on prehospital ultrasound, we conducted a narrative review of the literature.Results: Following a keyword search of MEDLINE in Ovid from inception to August 2, 2022, 2,564 records were identified and screened. Based on review of abstracts and full texts, with addition of seven articles via bibliography review, 193 records were included. Many included studies detail usage in air medical and other critical care transport environments. Clinicians performing prehospital ultrasound are often physicians or other advanced practice personnel who have previous ultrasound experience, which facilitates implementation in the prehospital setting. Emerging literature details training programs for prehospital personnel who are novices to ultrasound, and implementation for some study types appears feasible without prior experience. Unique use scenarios that show promise include during critical care transport, for triage in austere settings, and for thoracic evaluation of patients at risk of life-threatening pathology.Conclusion: There is a growing mostly observational body of literature describing the use of ultrasound by prehospital personnel. Prehospital ultrasound has demonstrated feasibility for specific conditions, yet interventional studies evaluating benefit to patient outcomes are absent.

Prehospital portable ultrasound for safe and accurate prehospital needle thoracostomy: a pilot educational study

Background

Simulated needle thoracostomy (NT) using ultrasound may reduce potential injury, increase accuracy, and be as rapid to perform as the traditional landmark technique following a brief educational session. Our objective was to determine if the use of an educational session demonstrating the use of handheld ultrasound to Emergency Medical Services (EMS) staff to facilitate NT was both feasible, and an effective way of increasing the safety and efficacy of this procedure for rural EMS providers.

Methods

A pre/post-educational intervention on a convenience sample of rural North American EMS paramedics and nurses. Measurement of location and estimated depth of placement of needle thoracostomy with traditional landmark technique was completed and then repeated using handheld ultrasound following a training session on thoracic ultrasound and correct placement of NT.

Results

A total of 30 EMS practitioners participated. Seven were female (23.3%). There was a higher frequency of dangerous structures underlying the chosen location with the landmark technique 9/60 (15%) compared to the ultrasound technique 1/60 (1.7%) (p = 0.08). Mean time-to-site-selection for the landmark technique was shorter than the ultrasound technique at 10.7 s (range 3.35–45 s) vs. 19.9 s (range 7.8–50 s), respectively (p < 0.001). There was a lower proportion of correct location selection for the landmark technique 40/60 (66.7%) when compared to the ultrasound technique 51/60 (85%) (p = 0.019). With ultrasound, there was less variance between the estimated and measured depth of the pleural space with a mean difference of 0.033 cm (range 0–0.5 cm) when ultrasound was used as compared to a mean difference of 1.0375 cm (range 0–6 cm) for the landmark technique (95% CI for the difference 0.73–1.27 cm; p < 0.001).

Conclusions

Teaching ultrasound NT was feasible in our cohort. While time-to-site-selection for ultrasound-guided NT took longer than the landmark technique, it increased safe and accurate simulated NT placement with fewer identified potential iatrogenic injuries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13089-022-00270-w.

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).

Helicopter emergency medical services use of thoracic point of care ultrasound for pneumothorax: a systematic review and meta-analysis

Background

Auscultating for breath sounds to assess for pneumothorax in the helicopter emergency medical services (HEMS) settings can be extremely challenging. Thoracic point of care ultrasound (POCUS) offers a seemingly more useful visual (rather than audible) alternative. This review critically and quantitatively evaluates the use of thoracic POCUS for pneumothorax in the HEMS setting.

Methods

A systematic literature review with meta-analysis was conducted. Only papers reporting on patients undergoing POCUS for pneumothorax in the helicopter or pre-hospital setting were included. Primary outcome was accuracy, focusing on sensitivity and specificity. Secondary outcome was practicality. PubMed, Embase and the Cochrane Library were searched. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess validity of studies.

Results

Twelve studies reporting on n = 1,936 images from medical and trauma patients were included in qualitative synthesis. Studies were nearly all observational designs. Most images were acquired by nurses or paramedics who were previously novices to ultrasound. The reference standard was predominantly CT. Specificity results were unanimously precise and very high, whereas sensitivity results were imprecise and extremely variable. Meta-analysis of eight studies involving n = 1,713 images yielded pooled sensitivity 61% (95% CI: 27–87%; I² = 94%) and pooled specificity 99% (95% CI: 98–100%; I² = 89%). Six studies involving n = 315 images reported practicality. The highest or second highest categorisation of image quality was reported in around half of those images.

Conclusion

Thoracic POCUS is highly specific but has extremely variable sensitivity for pneumothorax when performed in the HEMS setting. This is from purely a diagnostic (not clinical) perspective. Sensitivity increases when only clinically significant pneumothoraces are considered. Case reports reveal thoracic POCUS can appropriately alter treatment and triage decisions, but only for a small number of patients. It appears predominantly useful in mitigating against unnecessary interventions. More research reporting patient focused outcomes is required. In the meantime, thoracic POCUS appears to offer a more appropriate visual alternative to auscultation for breath sounds when assessing for pneumothorax in the HEMS setting.

A novel optical technology based on 690 nm and 850 nm wavelengths to assist needle thoracostomy

The sensitivity of pneumothorax diagnosis via handheld ultrasound is low, and there is no equipment suitable for use with life-threatening tension pneumothorax in a prehospital setting. This study proposes a novel technology involving optical fibers and near-infrared spectroscopy to assist in needle thoracostomy decompression. The proposed system via the optical fibers emitted dual wavelengths of 690 and 850 nm, allowing distinction among different layers of tissue in vivo. The fundamental principle is the modified Beer-Lambert law (MBLL) which is the basis of near-infrared tissue spectroscopy. Changes in optical density corresponding to different wavelengths (690 and 850 nm) and hemoglobin parameters (levels of Hb and HbO₂) were examined. The Kruskal-Wallis H test was used to compare the differences in parameter estimates among tissue layers; all p-values were < 0.001 relevant to 690 nm and 850 nm. In comparisons of Hb and HbO₂ levels relative to those observed in the vein and artery, all p-values were also < 0.001. This study proposes a new optical probe to assist needle thoracostomy in a swine model. Different types of tissue can be identified by changes in optical density and hemoglobin parameters. The aid of the proposed system may yield fewer complications and a higher success rate in needle thoracostomy procedures.

Immediate Pneumothorax Diagnosis by Surgical Residents Using Portable Ultrasound

OBJECTIVE

Feasibility of diagnosis of pneumothorax using handheld ultrasound by non-radiologists shows inconsistent results. The aim of this study is to evaluate the feasibility and accuracy of portable ultrasound for immediate diagnosis of pneumothorax by general surgery residents who underwent short training.

METHODS

Patients who presented to the emergency department of a university hospital with suspected pneumothorax between 10/2018 and 12/2019 were included in the study. Patients underwent ultrasound in 2 points of each hemithorax. Sensitivity and specificity for pneumothorax diagnosis by ultrasound and physical examination were calculated and compared with chest computed tomography (CT). Patients in whom a chest tube was placed prior to ultrasound examination and those who did not undergo a CT scan were excluded from the study.

RESULTS

A total of 85 patients met the inclusion criteria. Mean age was 40.7 ± 20.2 years. Pneumothorax was found among 46 patients (54%) per chest CT, and of these, 21 (46%) underwent chest tube placement following imaging. Ultrasound showed the highest sensitivity and specificity (95.6% [95% confidence interval {CI} 85.16% to 99.47%] and 97.44% [95% CI 86.40% to 99.67%], respectively). Chest x-ray had the lowest sensitivity (47.8% [95% CI 32.89% to 63.05%]) for pneumothorax detection. Physical examination showed a moderate sensitivity and specificity (82.6% [95% CI 68.58% to 92.18%] and 77.89% [95% CI 60.67% to 88.87%], respectively) for the diagnosis of pneumothorax.

CONCLUSIONS

We found high accuracy rates of 2-point ultrasound in immediate pneumothorax diagnosis when performed by surgical residents who underwent a short ultrasound training. This is a fast and repeatable test, and has the potential for successful implementation in prehospital and military scenarios as well, minimizing unnecessary chest tube placements.

A comparison of physician-staffed helicopters and ground ambulances transport for the outcome of severe thoracic trauma patients

PURPOSE

We retrospectively investigated prognostic factors for severe thoracic trauma patients evacuated by a physician-staffed helicopter emergency medical service (HEMS) and ground ambulance using the Japan Trauma Data Bank (JTDB).

METHODS

This study was a retrospective analysis of the JTDB database. The study period was from January 2004 to May 2019. The subjects were divided into two groups, according to the type of transportation: the Heli group included cases transported by the HEMS, while the Ambulance group included cases transported by ground ambulance.

RESULTS

During the investigation period, a total of 57,872 patients were enrolled as subjects, including 7238 in the Heli group and 50,634 in the Ambulance group. The average age, male ratio, average injury severity score (ISS), average revised trauma score (RTS) and survival ratio were significantly greater in the Heli group than in the Ambulance group. After performing a propensity score-matched analysis, there were no statistical differences concerning the age, sex, ISS, RTS between the two groups. However, the survival ratio in the Heli group remained greater than that in the Ambulance group. When variables that showed statistical significance in the univariate analysis were included in a multivariate analysis, the RTS, transport by the HEMS, age, ISS and female gender were identified as significant predictors of a survival outcome. The HEMS was significantly associated with an increased survival ratio (odds ratio: 1.69; 95% confidence interval: 1.51-1.88) compared with a ground ambulance.

CONCLUSION

The present study showed that transport by the HEMS improved the survival rate compared to that by a ground ambulance for patients with severe thoracic trauma.

The REBOA window: a cadaveric study delineating the optimum site for austere cannulation of the femoral artery for resuscitative endovascular balloon occlusion of the aorta

INTRODUCTION

Haemorrhage is the major cause of early mortality following traumatic injury. Patients suffering from non-compressible torso haemorrhage are more likely to suffer early death. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) can be effective in initial resuscitation; however, establishing swift arterial access is challenging, particularly in a severe shock. This is made more difficult by anatomical variability of the femoral vessels.

METHODS

The femoral vessels were characterised in 81 cadaveric lower limbs, measuring specifically the distance from the inferior border of the inguinal ligament to the distal part of the origin of the profunda femoris artery (PFA), and from the distal part of the origin of the PFA to where the femoral vein lies posterior to and is completely overlapped by the femoral artery.

RESULTS

The femoral vein lay deep to the femoral artery at a mean distance of 105 mm from the inferior border of the inguinal ligament. The PFA arose from the femoral artery at a mean distance of 51.1 mm from the inguinal ligament. From the results, it is predicted that the PFA originates from the common femoral artery approximately 24 mm from the inguinal ligament, and the femoral vein is completely overlapped by the femoral artery by 67.7 mm distal from the inguinal ligament, in 95% of subjects.

CONCLUSIONS

Based on the results, proposed is an 'optimal access window' of up to 24 mm inferior to the inguinal ligament for common femoral arterial catheterisation for pre-hospital REBOA, or more simply within one finger breadth.