Is there a role for pre-hospital chest ultrasound in trauma patients?

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.

Point-of-care ultrasound at Role 1: is it time for a rethink?

Introduction

The past 20 years have seen a rapid increase in point-of-care ultrasound (POCUS) use in the prehospital sphere. However, in the British Army there is no POCUS capability in the Defence Primary Healthcare (DPHC) or deployed Role 1 setting. POCUS can improve diagnostic capability, influence management decisions and transfer destination, and is a useful triage tool in mass casualty management.

Method

A survey on POCUS use was sent to 279 clinicians working in the Role 1, civilian prehospital and Defence Primary Healthcare environments. Questions explored current levels of experience and training, indications for use and attitudes towards roll out. Results were analysed using a mixed methods approach.

Results

There were 124 respondents (279 recipients; 44.4% response rate). 74.2% (92 respondents) had no experience of using POCUS while 9.7% (12 respondents) were classed as frequent users. The four most common indications for prehospital POCUS were abdominal, cardiac and lung imaging and vascular access. The majority of respondents felt that POCUS would add value in the deployed Role 1 environment; this was even more evident in the frequent user group. Common concerns were difficulty maintaining currency, governance burden and uncertainty over impact on management.

Conclusion

The majority of doctors surveyed feel that POCUS would add value at Role 1 and is a capability that should be developed. The authors will watch with interest the progress of Project MORPHO.

Five-year Retrospective Review of Physician and Non-physician Performed Ultrasound in a Canadian Critical Care Helicopter Emergency Medical Service

OBJECTIVE

To describe the use of prehospital ultrasonography (PHUS) to support interventions, when used by physician and non-physician air medical crew (AMC), in a Canadian helicopter emergency medical service (HEMS).

METHODS

A retrospective review was conducted of consecutive patients who underwent ultrasound examination during HEMS care from January 1, 2009 through March 10, 2014. An a priori created data form was used to record patient demographics, type of ultrasound scan performed, ultrasound findings, location of scan, type of interventions supported by PHUS, factors that affected PHUS completion, and quality indicator(s). Data analysis was performed through descriptive statistics, Student's t-test for continuous variables, Z-test for proportions, and Mann-Whitney U Test for nonparametric data. Outcomes included interventions supported by PHUS, factors associated with incomplete scans, and quality indicators associated with PHUS use. Differences between physician and AMC groups were also assessed.

RESULTS

PHUS was used in 455 missions, 318 by AMC and 137 by physicians. In combined trauma and medical patients, in the AMC group interventions were supported by PHUS in 26% of cases (95% CI 18-34). For transport physicians the percentage support was found to be significantly greater at 45% of cases (95% CI 34-56) p = < 0.006. Incomplete PHUS scans were common and reasons included patient obesity, lack of time, patient access, and clinical reasons. Quality indicators associated with PHUS were rarely identified.

CONCLUSIONS

The use of PHUS by both physicians and non-physicians was found to support interventions in select trauma and medical patients. Key words: emergency medical services; aircraft; helicopter; air ambulance; ultrasonography; emergency care, prehospital; prehospital emergency care.

Prehospital ultrasound of the abdomen and thorax changes trauma patient management: A systematic review

BACKGROUND

Ultrasound examination of trauma patients is increasingly performed in prehospital services. It is unclear if prehospital sonographic assessments change patient management: providing prehospital diagnosis and treatment, determining choice of destination hospital, or treatment at the receiving hospital.

OBJECTIVE

This review aims to assess and grade the evidence that specifically examines whether prehospital ultrasound (PHUS) of the thorax and/or abdomen changes management of the trauma patient.

METHODS

A systematic review was conducted of trauma patients who had an ultrasound of the thorax or abdomen performed in the prehospital setting. PubMed, MEDLINE, Web of Science (CINAHL, EMBASE, Cochrane Central Register of Controlled Trials) and the reference lists of included studies were searched. Methodological quality was checked and risk of bias analysis performed, a level of evidence grade was assigned, and descriptive data analysis performed.

RESULTS

992 unique citations were identified, which included eight studies that met inclusion criteria with a total of 925 patients. There are no reports of randomised controlled trials. Heterogeneity exists between the included studies which ranged from a case series to retrospective and prospective non-randomised observational studies. Three studies achieved a 2+ Scottish Intercollegiate Guidelines Networks grade for quality of evidence and the remainder demonstrated a high risk of bias. The three best studies each provided examples of prehospital ultrasound positively changing patient management.

CONCLUSION

There is moderate evidence that supports prehospital physician use of ultrasound for trauma patients. For some patients, management was changed based on the results of the PHUS. The benefit of ultrasound use in non-physician services is unclear.