A protocol for the ERICA-ARREST feasibility study of Emergency Resuscitative Endovascular Balloon occlusion of the Aorta in Out-of-Hospital Cardiac Arrest.

Background: Fewer than one in ten out-of-hospital cardiac arrest (OHCA) patients survive to hospital discharge in the UK. For prehospital teams to improve outcomes in patients who remain in refractory OHCA despite advanced life support (ALS); novel strategies that increase the likelihood of return of spontaneous circulation, whilst preserving cerebral circulation, should be investigated. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) has been shown to improve coronary and cerebral perfusion during cardiopulmonary resuscitation. Early, prehospital initiation of REBOA may improve outcomes in patients who do not respond to standard ALS. However, there are significant clinical, technical, and logistical challenges with rapidly delivering prehospital REBOA in OHCA; and the feasibility of delivering this intervention in the UK urban-rural setting has not been evaluated. Methods: The Emergency Resuscitative Endovascular Balloon Occlusion of the Aorta in Out-of-Hospital Cardiac Arrest (ERICA-ARREST) study is a prospective, single-arm, interventional feasibility study. The trial will enrol 20 adult patients with non-traumatic OHCA. The primary objective is to assess the feasibility of performing Zone I (supra-coeliac) aortic occlusion in patients who remain in OHCA despite standard ALS in the UK prehospital setting. The trial's secondary objectives are to describe the hemodynamic and physiological responses to aortic occlusion; to report key time intervals; and to document adverse events when performing REBOA in this context. Discussion: Using compressed geography, and targeted dispatch, alongside a well-established femoral arterial access programme, the ERICA-ARREST study will assess the feasibility of deploying REBOA in OHCA in a mixed UK urban and rural setting.Trial registration.ClinicalTrials.gov (NCT06071910), registration date October 10, 2023, https://classic.clinicaltrials.gov/ct2/show/NCT06071910.

Implementation of a point-of-care ultrasound archiving system and governance framework in a UK physician-paramedic staffed helicopter emergency medical service.

INTRODUCTION: There has been a rapid expansion in the use of point-of-care ultrasonography (POCUS) by emergency medical services (EMS). However, less than a third of UK EMS utilise imaging archiving for POCUS, and fewer review saved images as part of a clinical governance structure. This paper describes the implementation of a novel image archiving system and a robust clinical governance framework in our UK physician-paramedic staffed helicopter emergency medical service (HEMS). METHODS: A retrospective database review was conducted of all patients attended by East Anglian Air Ambulance (EAAA) between the introduction of a new POCUS device and image archiving system on 1 December 2020 to 31 January 2024. All patients with recorded POCUS examinations were included. Images from POCUS examinations at EAAA are archived on a cloud-based server, and retrospectively reviewed within 24 h by an EAAA POCUS supervisor. Image quality is graded using a 5-point Likert-type scale, agreement between reviewer and clinician is recorded and feedback is provided on scanning technique. T-tests were used to assess the difference in image quality between physicians and paramedics. Inter-rater reliability between reviewers and clinicians was assessed using Cohen's kappa (κ). RESULTS: During the study period, 5913 patients were attended by EAAA. Of these, 1097 patients had POCUS images recorded. The prevalence of POCUS during the study period was 18.6%. 1061 patient examinations underwent quality assurance (96.7%). The most common POCUS examination was echocardiography (60%), predominantly during cardiac arrest. The primary scanning clinician was a paramedic in 25.4% of POCUS examinations. Across all examination types; image quality was not significantly different between physicians and paramedics and agreement between reviewers and clinicians was strong (κ > 0.85). CONCLUSIONS: In this service evaluation study, we have described outcomes following the introduction of a new POCUS device, image archiving system and governance framework in our HEMS. Paramedics were the primary scanning clinician in a quarter of scans, with image quality comparable to physicians. Almost all scans underwent quality assurance and inter-rater reliability was strong between clinicians and reviewers. Further research is required to investigate the diagnostic accuracy of POCUS and to demonstrate the effect of utilising prehospital POCUS to refine diagnosis on clinical outcomes.

Implementation of advanced vascular access, physiological monitoring and goal-directed resuscitation during OHCA in a helicopter emergency medical service.

Outcomes after out-of-hospital cardiac arrest (OHCA) remain poor in the UK. In order to increase the chances of successful resuscitation, international society guidelines on cardiopulmonary resuscitation quality have recommended titration of chest compression parameters and vasopressor administration to arterial diastolic blood pressure if invasive catheters are in situ at the time of cardiac arrest. However, prehospital initiation of arterial and central venous catheterisation is seldom undertaken due to the risks and significant technical challenges in the context of ongoing resuscitation in this environment. In 2019, a dedicated programme was started at East Anglian Air Ambulance (EAAA) to enable the safe introduction of contemporary emergency vascular access devices, in order to improve physiological monitoring intra-arrest and deliver nuanced, goal-directed resuscitation in OHCA patients. This programme was entitled Specialist Percutaneous Emergency Aortic Resuscitation (SPEAR). This article details the EAAA SPEAR technique; and the development, implementation and governance of this novel endovascular strategy in our UK physician-paramedic staffed helicopter emergency medical service.

Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK helicopter emergency medical service- a retrospective observational review of practice.

BACKGROUND: Accurate haemodynamic monitoring in the prehospital setting is essential. Non-invasive blood pressure measurement is susceptible to vibration and motion artefact, especially at extremes of hypotension and hypertension: invasive arterial blood pressure (IABP) monitoring is a potential solution. This study describes the largest series to date of cases of IABP monitoring being initiated prehospital. METHODS: This retrospective observational study was conducted at East Anglian Air Ambulance (EAAA), a UK helicopter emergency medical service (HEMS). It included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 and 20th April 2023. The following data were retrieved for all patients: sex; age; aetiology (medical cardiac arrest, other medical emergency, trauma); site of arterial cannulation; operator role (doctor/paramedic); time of insertion and, where applicable, times of pre-hospital emergency anaesthesia, and return of spontaneous circulation following cardiac arrest. Descriptive analyses were performed to characterise the sample. RESULTS: 13,556 patients were attended: IABP monitoring was initiated in 1083 (8.0%) cases, with a median age 59 years, of which 70.8% were male. 546 cases were of medical cardiac arrest: in 22.4% of these IABP monitoring was initiated during cardiopulmonary resuscitation. 322 were trauma cases, and the remaining 215 were medical emergencies. The patients were critically unwell: 981 required intubation, of which 789 underwent prehospital emergency anaesthesia; 609 received vasoactive medication. In 424 cases IABP monitoring was instituted en route to hospital. CONCLUSION: This study describes over 1000 cases of prehospital arterial catheterisation and IABP monitoring in a UK HEMS system and has demonstrated feasibility at scale. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting.

Selective aortic arch perfusion: a first-in-human observational cadaveric study.

BACKGROUND: Selective aortic arch perfusion (SAAP) is a novel endovascular technique that combines thoracic aortic occlusion with extracorporeal perfusion of the brain and heart. SAAP may have a role in both haemorrhagic shock and in cardiac arrest due to coronary ischaemia. Despite promising animal studies, no data is available that describes SAAP in humans. The primary aim of this study was to assess the feasibility of selective aortic arch perfusion in humans. The secondary aim of the study was to assess the feasibility of achieving direct coronary artery access via the SAAP catheter as a potential conduit for salvage percutaneous coronary intervention. METHODS: Using perfused human cadavers, a prototype SAAP catheter was inserted into the descending aorta under fluoroscopic guidance via a standard femoral percutaneous access device. The catheter balloon was inflated and the aortic arch perfused with radio-opaque contrast. The coronary arteries were cannulated through the SAAP catheter. RESULTS: The procedure was conducted four times. During the first two trials the SAAP catheter was passed rapidly and without incident to the intended descending aortic landing zone and aortic arch perfusion was successfully delivered via the device. The SAAP catheter balloon failed on the third trial. On the fourth trial the left coronary system was cannulated using a 5Fr coronary guiding catheter through the central SAAP catheter lumen. CONCLUSIONS: For the first time using a perfused cadaveric model we have demonstrated that a SAAP catheter can be easily and safely inserted and SAAP can be achieved using conventional endovascular techniques. The SAAP catheter allowed successful access to the proximal aorta and permitted retrograde perfusion of the coronary and cerebral circulation.

Use of Topical Hemostatic Dressings in an Extended Field Care Model.

BACKGROUND: We sought to test whether Celox topical hemostatic dressing (Medtrade Products) would maintain hemostasis in extended use. METHODS: An anesthetized swine underwent bilateral arteriotomies and treatment with topical hemostatic dressings in line with the Kheirabadi method. The dressings were covered with standard field dressings, and these were visually inspected for bleeding every 2 hours until 8 hours, when the swine was euthanized. RESULTS: There was no evidence of rebleeding at any point up to and including 8 hours. The Celox dressings maintained hemostasis in extended use. CONCLUSION: Celox topical hemostatic dressing is effective for extended use and maintains hemostasis. It should be considered for use in situations in which evacuation and definitive care may be delayed.