Balloon Occlusion

Animal investigations were carried out in accordance with the “Position of the American Heart Association on Research Animal Use,” as adopted by the AHA on November 11, 1984. The study was approved by the Ethics Committee on Animal Experimentation at the University of Kaposvar, Hungary. The study design is displayed in Fig. 1.
Domestic pigs underwent cardiac catheterization (Supplementary Methods). The r-I/R protocol consisted of three repetitive cycles of 10 min I/R via percutaneous balloon occlusion and deflation in the mid left anterior descending coronary artery (LAD) under general anesthesia. Details are described in the Supplementary Methods.

The study involved semi-structured interviews with two cohorts of participants: the first cohort were individuals who had been involved in pre-hospital trials (both trauma and non-trauma) in either a strategic or operational capacity (across different roles) within the UK — referred to herein as ‘Pre-hospital trial researchers’. This cohort was sampled to assess the broad challenges across pre-hospital trials. These interviews were intended to be open and without an a priori specific behaviour of interest and as such data collection was not structured around a theoretical framework. However, we did apply the Capability Opportunity Motivation-Behaviour (COM-B) framework to inform the data analysis (process outlined below). The COM-B framework was developed to understand the factors that influence behaviour, namely in relation to an individuals’ capabilities (physical/psychological), opportunities (physical/social environmental factors) and motivation (reflective/automatic) [11 (link)].
The second cohort were individuals involved in the recruitment and intervention delivery to the P-PRO study (Pre-hospital Zone 1 Partial Resuscitative Endovascular Balloon Occlusion of the Aorta for injured patients with exsanguinating sub-diaphragmatic haemorrhage) — referred to herein as ‘P-PRO clinical investigators’. P-PRO is an observational cohort study investigating the feasibility of pre-hospital Zone 1 partial Resuscitative Endovascular Balloon Occlusion of the Aorta (P-REBOA). REBOA is a complex intervention that involves the insertion of an aortic balloon occlusion catheter into the thoracoabdominal aorta. REBOA is not routinely available within the UK in either the pre-hospital or in-hospital setting. However, this intervention is currently being evaluated in the Emergency Department setting by the UK REBOA Trial. Pre-hospital REBOA has been in use by London HEMS since 2014 targeting the distal aorta (Zone 3), for the management of severe pelvic haemorrhage [12 , 13 (link)]. Zone 1 P-REBOA describes an evolution of this technique involving balloon positioning in the thoracic aorta for patients with sub-diaphragmatic haemorrhage and severe, immediately life-threatening shock, combined with a procedural adaptation to allow some blood flow past the balloon.
In the P-PRO Study, London HEMS teams are tasked with deploying Zone 1 P-REBOA in patients in the pre-hospital setting. The balloon is positioned above the level of suspected haemorrhage and inflated to augment aortic blood pressure above the balloon whilst reducing bleeding below. Once the haemodynamics have stabilised, the balloon is partially deflated to allow some controlled distal blood flow (P-REBOA) and therefore oxygen delivery, to mitigate against the ischaemia that is otherwise created. P-PRO clinical investigators then transport patients to the nearest Major Trauma Centre, whilst managing the balloon in situ.
Interviews with the P-PRO clinical investigators were narrower in focus with specific behaviours of interest to be investigated (recruitment and intervention delivery in a future trial). As such data collection and analysis was informed by the Theoretical Domains Framework (TDF). The TDF is an established behavioural framework that integrates 33 theories of behaviour into 14 domains that inhibit or enable behaviour (knowledge, skills; social/professional role and identity; beliefs about capabilities; beliefs about consequences; optimism; reinforcement; intentions; goals; memory/attention/decision processes; environmental context and resources; social influences; emotion; behavioural regulation) [17 ]. Domains of the TDF can be mapped onto components of the COM-B framework [12 ].

This is a retrospective review of a consecutive series of patients with large air leaks related to SARS-CoV-2 infection. All patients were admitted to the high-volume specialist ECMO intensive care unit (ICU) at Guy’s and St Thomas’ Hospitals in London with severe respiratory failure requiring VV-ECMO. Standard lung rest settings at admission were mandatory pressure control ventilation, with driving pressure of 10 cm H₂O, PEEP $\le$ 10 cm H₂O and a respiratory rate of 10. Patients were considered for endobronchial valve (EBV) placement if there were persistent (>10 days), large air leaks (>500 mL/min) despite conventional therapy (optimal pleural drainage, reduced mechanical ventilator pressure, lung rest, attempted recruitment of collapsed lung segments, and isolated lung ventilation and pleurodesis where indicated). Multidisciplinary discussion between teams from ICU, respiratory medicine and thoracic surgery had deemed that no other methods of management of the air leaks were feasible, including lung surgery.
EBV deployment was performed in all cases at the bedside in ICU (see Figure 1). A 2.8 size fibreoptic bronchoscope was used via the endotracheal or tracheostomy tube. Selection for the site of EBV placement was assessed using sequential balloon occlusion of lobar then segmental bronchi while observing for immediate cessation of air leak at the pleural drains. Once the source of the air leak was identified, an appropriate-sized Zephyr^® endobronchial valve (4.0–5.5 mm, Pulmonx, Redwood City, CA, USA) was deployed to occlude the segment or lobe. Consent for the procedure was obtained as per hospital policy in adults who lacked capacity to consent to investigations or treatment, and risks and benefits were discussed with patients’ families. All procedures were performed by a thoracic surgeon experienced in the procedure. Maintained cessation of air leaks was subsequently confirmed with the absence of both bubbling from an under-water seal pleural drain system and measured minute volume leak on the ventilator.
Patient characteristics and clinical data were collected retrospectively from a prospectively maintained patient electronic health record (Intellispace Critical Care and Anaesthesia, Philips Healthcare, Koninklijke, Amsterdam, the Netherlands). Imaging data were collected from an electronic radiology reporting system (PACS, Sectra Medical, Linköping, Sweden). Continuous data were reported as mean and standard deviation or range, and categorical data were reported as count and percentage. Survival was measured from the date of hospital discharge. Ethical approval was sought and waived on the basis that this was a retrospective study.