Prehospital Partial Resuscitative Endovascular Balloon Occlusion of the Aorta for Exsanguinating Subdiaphragmatic Hemorrhage.

Importance: Hemorrhage is the most common cause of preventable death after injury. Most deaths occur early, in the prehospital phase of care. Objective: To establish whether prehospital zone 1 (supraceliac) partial resuscitative endovascular balloon occlusion of the aorta (Z1 P-REBOA) can be achieved in the resuscitation of adult trauma patients at risk of cardiac arrest and death due to exsanguination. Design, Setting, and Participants: This was a prospective observational cohort study (Idea, Development, Exploration, Assessment and Long-term follow-up [IDEAL] 2A design) with recruitment from June 2020 to March 2022 and follow-up until discharge from hospital, death, or 90 days evaluating a physician-led and physician-delivered, urban prehospital trauma service in the Greater London area. Trauma patients aged 16 years and older with suspected exsanguinating subdiaphragmatic hemorrhage, recent or imminent hypovolemic traumatic cardiac arrest (TCA) were included. Those with unsurvivable injuries or who were pregnant were excluded. Of 2960 individuals attended by the service during the study period, 16 were included in the study. Exposures: ZI REBOA or P-REBOA. Main Outcomes and Measures: The main outcome was the proportion of patients in whom Z1 REBOA and Z1 P-REBOA were achieved. Clinical end points included systolic blood pressure (SBP) response to Z1 REBOA, mortality rate (1 hour, 3 hours, 24 hours, or 30 days postinjury), and survival to hospital discharge. Results: Femoral arterial access for Z1 REBOA was attempted in 16 patients (median [range] age, 30 [17-76] years; 14 [81%] male; median [IQR] Injury Severity Score, 50 [39-57]). In 2 patients with successful arterial access, REBOA was not attempted due to improvement in clinical condition. In the other 14 patients (8 [57%] of whom were in traumatic cardiac arrest [TCA]), 11 successfully underwent cannulation and had aortic balloons inflated in Z1. The 3 individuals in whom cannulation was unsuccessful were in TCA (failure rate = 3/14 [21%]). Median (IQR) pre-REBOA SBP in the 11 individuals for whom cannulation was successful (5 [46%] in TCA) was 47 (33-52) mm Hg. Z1 REBOA plus P-REBOA was associated with a significant improvement in BP (median [IQR] SBP at emergency department arrival, 101 [77-107] mm Hg; 0 of 10 patients were in TCA at arrival). The median group-level improvement in SBP from the pre-REBOA value was 52 (95% CI, 42-77) mm Hg (P < .004). P-REBOA was feasible in 8 individuals (8/11 [73%]) and occurred spontaneously in 4 of these. The 1- and 3-hour postinjury mortality rate was 9% (1/11), 24-hour mortality was 27% (3/11), and 30-day mortality was 82% (9/11). Survival to hospital discharge was 18% (2/11). Both survivors underwent early Z1 P-REBOA. Conclusions and Relevance: In this study, prehospital Z1 P-REBOA is feasible and may enable early survival, but with a significant incidence of late death. Trial Registration: ClinicalTrials.gov Identifier: NCT04145271.

Expert consensus on training and accreditation for extracorporeal cardiopulmonary resuscitation an international, multidisciplinary modified Delphi Study.

BACKGROUND: A multidisciplinary group of stakeholders were used to identify: (1) the core competencies of a training program required to perform in-hospital ECPR initiation (2) additional competencies required to perform pre-hospital ECPR initiation and; (3) the optimal training method and maintenance protocol for delivering an ECPR program. METHODS: A modified Delphi process was undertaken utilising two web based survey rounds and one virtual meeting. Experts rated the importance of different aspects of ECPR training, competency and governance on a 9-point Likert scale. A diverse, representative group was targeted. Consensus was achieved when greater than 70% respondents rated a domain as critical (> or = 7 on the 9 point Likert scale). RESULTS: 35 international ECPR experts from 9 countries formed the expert panel, with a median number of 14 years of ECMO practice (interquartile range 11-38). Participant response rates were 97% (survey round one), 63% (virtual meeting) and 100% (survey round two). After the second round of the survey, 47 consensus statements were formed outlining a core set of competencies required for ECPR provision. We identified key elements required to safely train and perform ECPR including skill pre-requisites, surrogate skill identification, the importance of competency-based assessment over volume of practice and competency requirements for successful ECPR practice and skill maintenance. CONCLUSIONS: We present a series of core competencies, training requirements and ongoing governance protocols to guide safe ECPR implementation. These findings can be used to develop training syllabus and guide minimum standards for competency as the growth of ECPR practitioners continues.

A retrospective analysis of inpatient cardiac arrests over one year at a tertiary heart attack and cardiothoracic centre identifying potential candidates for an inpatient extracorporeal cardiopulmonary resuscitation service.

INTRODUCTION: Extracorporeal cardiopulmonary resuscitation (ECPR) is an internationally recognised treatment for refractory cardiac arrest, with evidence of improved outcomes in selected patient groups from cohort studies and case series. In order to establish the clinical need for an in-hospital extracorporeal cardiopulmonary resuscitation service at a tertiary cardiac centre, we analysed the inpatient cardiac arrest database for the previous 12 months. METHODS: Evidence-based inclusion criteria were used to retrospectively identify the number of patients potentially eligible for extracorporeal cardiopulmonary resuscitation over a 12-month period. RESULTS: A total of 261 inpatient cardiac arrests were analysed with 21 potential extracorporeal cardiopulmonary resuscitation candidates meeting the inclusion criteria (1.75 patients per month, or 8% of inpatient cardiac arrests (21/261)). The majority (71%) of these cardiac arrests occurred outside of normal working hours. Survival-to-discharge within this sub-group with conventional cardiopulmonary resuscitation was 19% (4/21). CONCLUSION: Sufficient numbers of refractory inpatient cardiac arrests occur to justify an extracorporeal cardiopulmonary resuscitation service, but a 24-h on-site extracorporeal membrane oxygenation team presents a significant financial and logistical challenge.

Sub30: Protocol for the Sub30 feasibility study of a pre-hospital Extracorporeal membrane oxygenation (ECMO) capable advanced resuscitation team at achieving blood flow within 30 ​min in patients with refractory out-of-hospital cardiac arrest.

BACKGROUND: Out-of-hospital cardiac arrest carries a poor prognosis with survival less than 10% in many patient cohorts. Survival is inversely associated with duration of resuscitation as external chest compressions do not provide sufficient blood flow to prevent irreversible organ damage during a prolonged resuscitation. Extracorporeal membrane oxygenation (ECMO) instituted during cardiac arrest can provide normal physiological blood flows and is termed Extracorporeal Cardio-Pulmonary Resuscitation (ECPR). ECPR may improve survival when used with in-hospital cardiac arrests. This possible survival benefit has not been replicated in trials of out-of-hospital cardiac arrests, possibly because of the additional time it takes to transport the patient to hospital and initiate ECPR. Pre-hospital ECPR may shorten the time between cardiac arrest and physiological blood flows, potentially improving survival. It may also mitigate some of the neurological injury that many survivors suffer. METHODS: Sub30 is a prospective six patient feasibility study. The primary aim is to test whether it is possible to institute ECPR within 30 ​min of collapse in adult patients with refractory out of hospital cardiac arrest (OHCA). The secondary aims are to gather preliminary data on clinical outcomes, resource utilisation, and health economics associated with rapid ECPR delivery in order to plan any subsequent clinical investigation or clinical service. On study days a dedicated fast-response vehicle with ECPR capability will be tasked to out-of-hospital cardiac arrests in an area of London served by Barts Heart Centre. If patients suffer a cardiac arrest refractory to standard advanced resuscitation and meet eligibility criteria, ECPR will be started in the pre-hospital environment. DISCUSSION: Delivering pre-hospital ECPR within 30 ​min of an out-of-hospital cardiac arrest presents significant ethical, clinical, governance and logistical challenges. Prior to conducting an efficacy study of ECPR the feasibility of timely and safe application must be demonstrated first. Extensive planning, multiple high-fidelity multiagency simulations and a unique collaboration between pre-hospital and in-hospital institutions will allow us to test the feasibility of this intervention in London. The study has been reviewed, refined and endorsed by the International ECMO Network (ECMONet). TRIAL REGISTRATION: Clinicaltrials. gov NCT03700125, prospectively registered October 9, 2018.

A systematic literature review and meta-analysis of the effectiveness of extracorporeal-CPR versus conventional-CPR for adult patients in cardiac arrest.

INTRODUCTION: The probability of surviving a cardiac arrest remains low. International resuscitation guidelines state that extracorporeal cardiopulmonary resuscitation (ECPR) may have a role in selected patients suffering refractory cardiac arrest. Identifying these patients is challenging. This project systematically reviewed the evidence comparing the outcomes of ECPR over conventional-CPR (CCPR), before examining resuscitation-specific parameters to assess which patients might benefit from ECPR. METHOD: Literature searches of studies comparing ECPR to CCPR and the clinical parameters of survivors of ECPR were performed. The primary outcome examined was survival at hospital discharge or 30 days. A secondary analysis examined the resuscitation parameters that may be associated with survival in patients who receive ECPR (no-flow and low-flow intervals, bystander-CPR, initial shockable cardiac rhythm, and witnessed cardiac arrest). RESULTS: Seventeen of 948 examined studies were included. ECPR demonstrated improved survival (OR 0.40 (0.27-0.60)) and a better neurological outcome (OR 0.10 (0.04-0.27)) over CCPR during literature review and meta-analysis. Characteristics that were associated with improved survival in patients receiving ECPR included an initial shockable rhythm and a shorter low-flow time. Shorter no-flow, the presence of bystander-CPR and witnessed arrests were not characteristics that were associated with improved survival following meta-analysis, although the quality of input data was low. All data were non-randomised, and hence the potential for bias is high. CONCLUSION: ECPR is a sophisticated treatment option which may improve outcomes in a selected patient population in refractory cardiac arrest. Further comparative research is needed clarify the role of this potential resuscitative therapy.

Trauma induced acute kidney injury.

BACKGROUND: Injured patients are at risk of developing acute kidney injury (AKI), which is associated with increased morbidity and mortality. The aim of this study is to describe the incidence, timing, and severity of AKI in a large trauma population, identify risk factors for AKI, and report mortality outcomes. METHODS: A prospective observational study of injured adults, who met local criteria for trauma team activation, and were admitted to a UK Major Trauma Centre. AKI was defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Multivariable logistic regression and Cox proportional hazard modelling was used to analyse parameters associated with AKI and mortality. RESULTS: Of the 1410 patients enrolled in the study, 178 (12.6%) developed AKI. Age; injury severity score (ISS); admission systolic blood pressure, lactate and serum creatinine; units of Packed Red Blood Cells transfused in first 24 hours and administration of nephrotoxic therapy were identified as independent risk factors for the development of AKI. Patients that developed AKI had significantly higher mortality than those with normal renal function (47/178 [26.4%] versus 128/1232 [10.4%]; OR 3.09 [2.12 to 4.53]; p<0.0001). After adjusting for other clinical prognostic factors, AKI was an independent risk factor for mortality. CONCLUSIONS: AKI is a frequent complication following trauma and is associated with prolonged hospital length of stay and increased mortality. Future research is needed to improve our ability to rapidly identify those at risk of AKI, and develop resuscitation strategies that preserve renal function in trauma patients.

Pre-hospital extra-corporeal cardiopulmonary resuscitation.

Survival from out-of-hospital cardiac arrest (OHCA) has remained low despite advances in resuscitation science. Hospital-based extra-corporeal cardiopulmonary resuscitation (ECPR) is a novel use of an established technology that provides greater blood flow and oxygen delivery during cardiac arrest than closed chest compressions. Hospital-based ECPR is currently offered to selected OHCA patients in specialized centres. The interval between collapse and restoration of circulation is inversely associated with good clinical outcomes after ECPR. Pre-hospital delivery of ECPR concurrent with conventional resuscitation is one approach to shortening this interval and improving outcomes after OHCA. This article examines the background and rationale for pre-hospital ECPR; summarises the findings of a literature search for published evidence; and considers candidate selection, logistics, and complications for this complex intervention.

Prevalence, natural history, and time-dependent outcomes of a multi-center North American cohort of out-of-hospital cardiac arrest extracorporeal CPR candidates.

AIM: Estimate prevalence of ECPR-eligible subjects in a large, North American, multi-center cohort, describe natural history with conventional resuscitation, and predict optimal timing of transition to ECPR. METHODS: Secondary analysis of clinical trial enrolling adults with non-traumatic OHCA. Primary outcome was survival to discharge with favorable outcome (mRS 0-3). Subjects were additionally classified as survival with unfavorable outcome (mRS 4-5), ROSC without survival (mRS 6), or without ROSC. We plotted subject accrual as a function of resuscitation duration (CPR onset to return of spontaneous circulation (ROSC) or termination of resuscitation), and estimated time-dependent probabilities of ROSC and mRS 0-3 at discharge. Adjusted logistic regression models tested the association between resuscitation duration and survival with mRS 0-3. RESULTS: Of 11,368 subjects, 1237 (10.9%; 95%CI 10.3-11.5%) were eligible for ECPR, Of these, 778 (63%) achieved ROSC, 466 (38%) survived to discharge, and 377 (30%) had mRS 0-3 at discharge. Half with eventual mRS 0-3 achieved ROSC within 8.8min (95%CI 8.3-9.2min) of resuscitation, and 90% within 21.0min (95%CI 19.1-23.7min). Time-dependent probabilities of ROSC and mRS 0-3 declined over elapsed resuscitation, and the likelihood of additional cases with mRS 0-3 beyond 20min was 8.4% (95%CI 5.9-11.0%). Resuscitation duration was independently associated with survival to discharge with mRS 0-3 (OR 0.95; 95%CI 0.92-0.97). CONCLUSION: Approximately 11% of subjects were eligible for ECPR. Only one-third survived to discharge with favorable outcome. Performing 9-21min of conventional resuscitation captured most ECPR-eligible subjects with eventual mRS 0-3 at hospital discharge.

Different sensations from cones with the same photopigment.

We used adaptive optics to study color fluctuation in the appearance of tiny flashes of light. For five subjects, near threshold, monochromatic stimuli with full widths at half maximum of 1/3 arcmin were delivered throughout a patch of retina near 1 deg in which we also determined the locations of L, M, and S cones. Subjects reported a wide variety of color sensations, even for long-wavelength stimuli, and all subjects reported blue or purple sensations at wavelengths for which S cones are insensitive. Subjects with more L cones reported more red sensations, and those with more M cones tended to report more green sensations. White responses increased linearly with the asymmetry in L to M cone ratio. The diversity in the color response could not be completely explained by combined L and M cone excitation, implying that photoreceptors within the same class can elicit more than one color sensation.

Adaptive optics for vision: the eye's adaptation to point spread function.

PURPOSE: Despite the fact that ocular aberrations blur retinal images, our subjective impression of the visual world is sharp, which suggests that the visual system compensates for subjective influence. If the brain adjusts for specific aberrations of the eye, vision should be clearest when looking through a subject's typical wave aberration rather than through an unfamiliar one. We used adaptive optics techniques to control the eye's aberrations in order to evaluate this hypothesis. METHODS: We used adaptive optics to produce point spread functions (PSFs) that were rotated versions of the eye's typical PSF by angles in 45 degrees intervals. Five normal subjects were asked to view a stimulus with their own PSF or with a rotated version, and to adjust the magnitude of the aberrations in the rotated case to match the subjective blur of the stimulus to that seen when the wave aberration was in typical orientation. RESULTS: The magnitude of the rotated wave aberration required to match the blur with the typical wave aberration was 20% to 40% less, indicating that subjective blur for the stimulus increased significantly when the PSF was rotated. CONCLUSION: These results support the hypothesis that the neural visual system is adapted to an eye's aberrations and has important implications for correcting higher order aberrations with customized refractive surgery or contact lenses. The full visual benefit of optimizing optical correction requires that the nervous system compensate for the new correction.

Neural compensation for the eye's optical aberrations.

A fundamental problem facing sensory systems is to recover useful information about the external world from signals that are corrupted by the sensory process itself. Retinal images in the human eye are affected by optical aberrations that cannot be corrected with ordinary spectacles or contact lenses, and the specific pattern of these aberrations is different in every eye. Though these aberrations always blur the retinal image, our subjective impression is that the visual world is sharp and clear, suggesting that the brain might compensate for their subjective influence. The recent introduction of adaptive optics to control the eye's aberrations now makes it possible to directly test this idea. If the brain compensates for the eye's aberrations, vision should be clearest with the eye's own aberrations rather than with unfamiliar ones. We asked subjects to view a stimulus through an adaptive optics system that either recreated their own aberrations or a rotated version of them. For all five subjects tested, the stimulus seen with the subject's own aberrations was always sharper than when seen through the rotated version. This supports the hypothesis that the neural visual system is adapted to the eye's aberrations, thereby removing somehow the effects of blur generated by the sensory apparatus from visual experience. This result could have important implications for methods to correct higher order aberrations with customized refractive surgery because some benefits of optimizing the correction optically might be undone by the nervous system's compensation for the old aberrations.

The human simulation lab-dissecting sex in the simulator lab: the clinical lacuna of transsexed embodiment.

This article begins with an ethnographically documented incident whereby nursing students dissected a medical human simulator model and rearranged it so that the "male" head and torso was attached to the "female" lower half. They then joked about the embodiment of the model, thus staging a scene of anti-trans ridicule. The students' lack of ability, or purposeful refusal, to recognize morphological biodiversity in medical settings indicates a lacuna in clinical imaginaries. Even as trans-identified and gender nonconforming people increasingly access care in the clinic, the lacuna of transsex-as a proxy term for non-binary embodiment-persists at the heart of clinical practice. This article concludes that we might engage in more ethical clinical practice if we recognize and affirm the trace of multiple forms of human being in the non-human simulator.

Accommodation with higher-order monochromatic aberrations corrected with adaptive optics.

Higher-order monochromatic aberrations in the human eye cause a difference in the appearance of stimuli at distances nearer and farther from best focus that could serve as a signed error signal for accommodation. We explored whether higher-order monochromatic aberrations affect the accommodative response to 0.5 D step changes in vergence in experiments in which these aberrations were either present as they normally are or removed with adaptive optics. Of six subjects, one could not accommodate at all for steps in either condition. One subject clearly required higher-order aberrations to accommodate at all. The remaining four subjects could accommodate in the correct direction even when higher-order aberrations were removed. No subjects improved their accommodation when higher-order aberrations were corrected, indicating that the corresponding decrease in the depth of field of the eye did not improve the accommodative response. These results are consistent with previous findings of large individual differences in the ability to accommodate in impoverished conditions. These results suggest that at least some subjects can use monochromatic higher-order aberrations to guide accommodation. They also show that some subjects can accommodate correctly when higher-order monochromatic aberrations as well as established cues to accommodation are greatly reduced.