Underlying reasons for sex difference in survival following out-of-hospital cardiac arrest: a mediation analysis.

AIMS: Previous studies have indicated a poorer survival among women following out-of-hospital cardiac arrest (OHCA), but the mechanisms explaining this difference remain largely uncertain.This study aimed to assess the survival after OHCA among women and men and explore the role of potential mediators, such as resuscitation characteristics, prior comorbidity, and socioeconomic factors. METHODS AND RESULTS: This was a population-based cohort study including emergency medical service-treated OHCA reported to the Swedish Registry for Cardiopulmonary Resuscitation in 2010-2020, linked to nationwide Swedish healthcare registries. The relative risks (RR) of 30-day survival were compared among women and men, and a mediation analysis was performed to investigate the importance of potential mediators. Total of 43 226 OHCAs were included, of which 14 249 (33.0%) were women. Women were older and had a lower proportion of shockable initial rhythm. The crude 30-day survival among women was 6.2% compared to 10.7% for men [RR 0.58, 95% confidence interval (CI) = 0.54-0.62]. Stepwise adjustment for shockable initial rhythm attenuated the association to RR 0.85 (95% CI = 0.79-0.91). Further adjustments for age and resuscitation factors attenuated the survival difference to null (RR 0.98; 95% CI = 0.92-1.05). Mediation analysis showed that shockable initial rhythm explained ∼50% of the negative association of female sex on survival. Older age and lower disposable income were the second and third most important variables, respectively. CONCLUSION: Women have a lower crude 30-day survival following OHCA compared to men. The poor prognosis is largely explained by a lower proportion of shockable initial rhythm, older age at presentation, and lower income.

Changes in temperature in preheated crystalloids at ambient temperatures relevant to a prehospital setting: an experimental simulation study with the application of prehospital treatment of trauma patients suffering from accidental hypothermia.

BACKGROUND: Accidental hypothermia is common in all trauma patients and contributes to the lethal diamond, increasing both morbidity and mortality. In hypotensive shock, fluid resuscitation is recommended using fluids with a temperature of 37-42°, as fluid temperature can decrease the patient's body temperature. In Sweden, virtually all prehospital services use preheated fluids. The aim of the present study was to investigate how the temperature of preheated infusion fluids is affected by the ambient temperatures and flow rates relevant for prehospital emergency care. METHODS: In this experimental simulation study, temperature changes in crystalloids preheated to 39 °C were evaluated. The fluid temperature changes were measured both in the infusion bag and at the patient end of the infusion system. Measurements were conducted in conditions relevant to prehospital emergency care, with ambient temperatures varying between - 4 and 28 °C and flow rates of 1000 ml/h and 6000 ml/h, through an uninsulated infusion set at a length of 175 cm. RESULTS: The flow rate and ambient temperature affected the temperature in the infusion fluid both in the infusion bag and at the patient end of the system. A lower ambient temperature and lower flow rate were both associated with a greater temperature loss in the infusion fluid. CONCLUSION: This study shows that both a high infusion rate and a high ambient temperature are needed if an infusion fluid preheated to 39 °C is to remain above 37 °C when it reaches the patient using a 175-cm-long uninsulated infusion set. It is apparent that the lower the ambient temperature, the higher the flow rate needs to be to limit temperature loss of the fluid.

Epidemiology of patients assessed for trauma by Swedish ambulance services: a retrospective registry study.

BACKGROUND: There is a lack of knowledge regarding the epidemiology of severe trauma assessed by Swedish emergency medical services (EMS). AIM: To investigate the prevalence of trauma in Sweden assessed by EMS from a national perspective and describe patient demography, aetiology, trauma type, prehospital triage and clinical outcomes. METHODS: Data from two national quality registries, the Swedish Ambulance Registry and the Swedish Trauma Registry (SweTrau) were collected from January 1 to December 31, 2019. Inclusion criteria were an Emergency Symptoms and Signs code equivalent to trauma in the Swedish Ambulance Registry and criteria fulfilled for SweTrau inclusion. Exclusion criteria were patients < 18 years old, those not transported to a hospital and those without a personal identification number. RESULTS: In total, 53,120 patients with trauma were included (14% of primary EMS missions involving a personal identification number). Of those, 2,278 (4.3%) patients (median age: 45 years; 32% women) were reported in SweTrau to have severe or potentially severe trauma (penetrating: 7%, blunt: 93%). In terms of including all causes of trauma, the code for 'trauma alert activation' was most frequent (55%). The most frequent injury mechanism was an injury caused by a car (34%). Most (89%) cases were assigned Priority 1 (life-threatening condition) at the dispatch centre. 62% were regarded as potentially life threatening upon EMS arrival, whereas 29% were assessed as non-life-threatening. Overall, 25% of the patients had new injury severity scores > 15. 12% required invasive treatment, 11% were discharged with severe disability and the 30-day mortality rate was 3.6%. CONCLUSION: In this cross-sectional study, 14% of the primary EMS missions for one year were caused by trauma. However, only a small proportion of these cases are severe injuries, and the risk of severe disabilities and death appears to be limited. The most frequent aetiology of a severe trauma is injury caused by a car, and most severe traumas are blunt. Severe traumas are given the highest priority at the dispatch centre in the vast majority of cases, but nearly one-third of these cases are considered a low priority by the EMS nurse. The latter leaves room for improvement.

Out-of-hospital cardiac arrest: Survival in children and young adults over 30 years, a nationwide registry-based cohort study.

OBJECTIVES: We studied short-term (30-day) and long-term (up to ten-year) survival among children and young adults following out-of-hospital cardiac arrest (OHCA) in Sweden over the course of the past 30 years. We also studied the causes of OHCA in children and examined predictors of survival. SETTING: This was a nationwide, registry-based cohort study, using the Swedish Registry of Cardiopulmonary Resuscitation. Our study comprised a cohort of 4,804 individuals aged 0 to 30 years who suffered OHCA between 1990 and 2020, in whom cardiopulmonary resuscitation (CPR) was initiated. We stratified the study cohort to distinct age groups and time periods. RESULTS: We found an increase in 30-day survival from 7% to 20% over the span of 30 years. In those under 1 year of age, survival increased from 2% to 19%. Time to CPR decreased from 14 to 2 min. The 10-year survival was high among those who survived 30 days. The etiology of cardiac arrests exhibited significant variations across different age groups but remained relatively consistent over time. Causes linked to mental illness constituted a substantial percentage of these cases. Compared to the reference period (1990-1994), the odds of survival in 2015-2020 was 3.00 (95% CI: 1.43, 6.94; p = 0.006). CONCLUSION: Survival rate after OHCA in children and young adults has increased three-fold over the past 30 years. Still overall mortality is high underscoring the need for continued efforts to mitigate risk factors and optimize survival.

Added predictive value of prehospital measurement of point-of-care lactate in an adult general EMS population in Sweden: a multi-centre observational study.

BACKGROUND: Emergency medical services (EMS) personnel must rapidly assess and transport patients with time-sensitive conditions to optimise patient outcomes. Serum lactate, a valuable in-hospital biomarker, has become more accessible in EMS settings through point-of-care (POC) testing. Although POC lactate levels are valuable in specific patient groups, its broader application in EMS remains unclear. This study assessed the additional predictive value of POC lactate levels in a general adult EMS population. METHODS: This prospective observational study (March 2018 to September 2019) involved two EMS organisations in Västra Götaland, Sweden. Patients were triaged using the Rapid Triage and Treatment System (RETTS). POC lactate levels were measured using StatStrip Xpress devices. Non-consecutive patients who received EMS and were aged 18 years and above were available for inclusion if triaged into RETTS levels: red, orange, yellow, or green if respiratory rate of ≥ 22 breaths/min. Outcomes were adverse outcomes, including a time-sensitive diagnosis, sequential organ failure assessment (SOFA) score ≥ 2, and 30-day mortality. Statistical analyses included descriptive statistics, imputation, and regression models to assess the impact of the addition of POC lactate levels to a base model (comprising patient age, sex, presence of past medical conditions, vital signs, pain, EMS response time, assessed triage condition, and triage level) and a RETTS triage model. RESULTS: Of 4,546 patients (median age 75 [57, 84] years; 49% male), 32.4% had time-sensitive conditions, 12.5% met the SOFA criteria, and 7.4% experienced 30-day mortality. The median POC lactate level was 1.7 (1.2, 2.5) mmol/L. Patients with time-sensitive conditions had higher lactate levels (1.9 mmol/L) than those with non-time-sensitive conditions (1.6 mmol/L). The probability of a time-sensitive condition increased with increasing lactate level. The addition of POC lactate marginally enhanced the predictive models, with a 1.5% and 4% increase for the base and RETTS triage models, respectively. POC lactate level as a sole predictor showed chance-only level predictive performance. CONCLUSIONS: Prehospital POC lactate assessment provided limited additional predictive value in a general adult EMS population. However, it may be beneficial in specific patient subgroups, emphasizing the need for its judicious use in prehospital settings.

The capacity of neurological pupil index to predict the absence of somatosensory evoked potentials after cardiac arrest - An observational study.

Background: In neurologic prognostication of comatose survivors from cardiac arrest, two independent predictors of poor outcome are the loss of the Pupillary light reflex (PLR) and the loss of the N20 response from Somatosensory Evoked potentials (SSEP). The PLR can be quantitatively assessed by pupillometry. Both tests depend on the midbrain, in which a dysfunction reflects a severe hypoxic injury. We reasoned that a certain level of defective PLR would be predictive of a bilaterally absent SSEP N20 response. Method: Neurological Pupil index (NPi) from the pupillometry and the SSEP N20 response were registered >48 h after cardiac arrest in comatose survivors. Clinical data were retrospectively analyzed. A receiver operating characteristic curve was used to evaluate the capacity of NPi to predict bilaterally absent SSEP N20 response. An NPi threshold value resulting in <5% false positive rate (FPR) for bilaterally absent N20 response was identified. Results: From February 2020 to August 2022, we included 54 patients out of which 49 had conclusive pupillometry and SSEP examinations. The NPi threshold value with FPR < 5% was 3.4, yielding 36% sensitivity (95% CI 18-55) and significantly discriminated between respective groups with preserved and bilaterally absent N20 response to SSEP (p-value <0.01). Conclusion: In this limited cohort, NPi < 3.4 in patients remaining comatose >48 hours after cardiac arrest predicted bilateral loss of the SSEP N20 response with a FPR < 5%. If validated in a larger cohort, an NPi threshold may be clinically applied in settings where SSEP is unavailable.

Compression-Only or Standard Cardiopulmonary Resuscitation for Trained Laypersons in Out-of-Hospital Cardiac Arrest: A Nationwide Randomized Trial in Sweden.

BACKGROUND: The ongoing TANGO2 (Telephone Assisted CPR. AN evaluation of efficacy amonGst cOmpression only and standard CPR) trial is designed to evaluate whether compression-only cardiopulmonary resuscitation (CPR) by trained laypersons is noninferior to standard CPR in adult out-of-hospital cardiac arrest. This pilot study assesses feasibility, safety, and intermediate clinical outcomes as part of the larger TANGO2 survival trial. METHODS: Emergency medical dispatch calls of suspected out-of-hospital cardiac arrest were screened for inclusion at 18 dispatch centers in Sweden between January 1, 2017, and March 12, 2020. Inclusion criteria were witnessed event, bystander on the scene with previous CPR training, age above 18 years of age, and no signs of trauma, pregnancy, or intoxication. Cases were randomized 1:1 at the dispatch center to either instructions to perform compression-only CPR (intervention) or instructions to perform standard CPR (control). Feasibility included evaluation of inclusion, randomization, and adherence to protocol. Safety measures were time to emergency medical service dispatch CPR instructions, and to start of CPR, intermediate clinical outcome was defined as 1-day survival. RESULTS: Of 11 838 calls of suspected out-of-hospital cardiac arrest screened for inclusion, 2168 were randomized and 1250 (57.7%) were out-of-hospital cardiac arrests treated by the emergency medical service. Of these, 640 were assigned to intervention and 610 to control. Crossover from intervention to control occurred in 16.3% and from control to intervention in 18.5%. The median time from emergency call to ambulance dispatch was 1 minute and 36 s (interquartile range, 1.1-2.2) in the intervention group and 1 minute and 30 s (interquartile range, 1.1-2.2) in the control group. Survival to 1 day was 28.6% versus 28.4% (P=0.984) for intervention and control, respectively. CONCLUSIONS: In this national randomized pilot trial, compression-only CPR versus standard CPR by trained laypersons was feasible. No differences in safety measures or short-term survival were found between the 2 strategies. Efforts to reduce crossover are important and may strengthen the ongoing main trial that will assess differences in long-term survival. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02401633.

Early ICD implantation following out-of-hospital cardiac arrest: a retrospective cohort study from the Swedish Registry for Cardiopulmonary Resuscitation.

BACKGROUND: It is unclear whether an implantable cardioverter-defibrillator (ICD) is generally beneficial in survivors of out-of-hospital cardiac arrest (OHCA). OBJECTIVE: We studied the association between ICD implantation prior to discharge and survival in patients with cardiac aetiology or initial shockable rhythm in OHCA. DESIGN: We conducted a retrospective cohort study in the Swedish Registry for Cardiopulmonary Resuscitation. Treatment associations were estimated using propensity scores. We used gradient boosting, Bayesian additive regression trees, neural networks, extreme gradient boosting and logistic regression to generate multiple propensity scores. We selected the model yielding maximum covariate balance to obtain weights, which were used in a Cox regression to calculate HRs for death or recurrent cardiac arrest. PARTICIPANTS: All cases discharged alive during 2010 to 2020 with a cardiac aetiology or initial shockable rhythm were included. A total of 959 individuals were discharged with an ICD, and 2046 were discharged without one. RESULTS: Among those experiencing events, 25% did so within 90 days in the ICD group, compared with 52% in the other group. All HRs favoured ICD implantation. The overall HR (95% CI) for ICD versus no ICD was 0.38 (0.26 to 0.56). The HR was 0.42 (0.28 to 0.63) in cases with initial shockable rhythm; 0.18 (0.06 to 0.58) in non-shockable rhythm; 0.32 (0.20 to 0.53) in cases with a history of coronary artery disease; 0.36 (0.22 to 0.61) in heart failure and 0.30 (0.13 to 0.69) in those with diabetes. Similar associations were noted in all subgroups. CONCLUSION: Among survivors of OHCA, those discharged with an ICD had approximately 60% lower risk of death or recurrent cardiac arrest. A randomised trial is warranted to study this further.

Prediction of survival in out-of-hospital cardiac arrest: the updated Swedish cardiac arrest risk score (SCARS) model.

Aims: Out-of-hospital cardiac arrest (OHCA) is a major health concern worldwide. Although one-third of all patients achieve a return of spontaneous circulation and may undergo a difficult period in the intensive care unit, only 1 in 10 survive. This study aims to improve our previously developed machine learning model for early prognostication of survival in OHCA. Methods and results: We studied all cases registered in the Swedish Cardiopulmonary Resuscitation Registry during 2010 and 2020 (n = 55 615). We compared the predictive performance of extreme gradient boosting (XGB), light gradient boosting machine (LightGBM), logistic regression, CatBoost, random forest, and TabNet. For each framework, we developed models that optimized (i) a weighted F1 score to penalize models that yielded more false negatives and (ii) a precision-recall area under the curve (PR AUC). LightGBM assigned higher importance values to a larger set of variables, while XGB made predictions using fewer predictors. The area under the curve receiver operating characteristic (AUC ROC) scores for LightGBM were 0.958 (optimized for weighted F1) and 0.961 (optimized for a PR AUC), while for XGB, the scores were 0.958 and 0.960, respectively. The calibration plots showed a subtle underestimation of survival for LightGBM, contrasting with a mild overestimation for XGB models. In the crucial range of 0-10% likelihood of survival, the XGB model, optimized with the PR AUC, emerged as a clinically safe model. Conclusion: We improved our previous prediction model by creating a parsimonious model with an AUC ROC at 0.96, with excellent calibration and no apparent risk of underestimating survival in the critical probability range (0-10%). The model is available at www.gocares.se.