Automatic assessment of left ventricular function for hemodynamic monitoring using artificial intelligence and transesophageal echocardiography.

We have developed a method to automatically assess LV function by measuring mitral annular plane systolic excursion (MAPSE) using artificial intelligence and transesophageal echocardiography (autoMAPSE). Our aim was to evaluate autoMAPSE as an automatic tool for rapid and quantitative assessment of LV function in critical care patients. In this retrospective study, we studied 40 critical care patients immediately after cardiac surgery. First, we recorded a set of echocardiographic data, consisting of three consecutive beats of midesophageal two- and four-chamber views. We then altered the patient's hemodynamics by positioning them in anti-Trendelenburg and repeated the recordings. We measured MAPSE manually and used autoMAPSE in all available heartbeats and in four LV walls. To assess the agreement with manual measurements, we used a modified Bland-Altman analysis. To assess the precision of each method, we calculated the least significant change (LSC). Finally, to assess trending ability, we calculated the concordance rates using a four-quadrant plot. We found that autoMAPSE measured MAPSE in almost every set of two- and four-chamber views (feasibility 95%). It took less than a second to measure and average MAPSE over three heartbeats. AutoMAPSE had a low bias (0.4 mm) and acceptable limits of agreement (- 3.7 to 4.5 mm). AutoMAPSE was more precise than manual measurements if it averaged more heartbeats. AutoMAPSE had acceptable trending ability (concordance rate 81%) during hemodynamic alterations. In conclusion, autoMAPSE is feasible as an automatic tool for rapid and quantitative assessment of LV function, indicating its potential for hemodynamic monitoring.

Exercise training reveals micro-RNAs associated with improved cardiac function and electrophysiology in rats with heart failure after myocardial infarction.

AIMS: Endurance training improves aerobic fitness and cardiac function in individuals with heart failure. However, the underlying mechanisms are not well characterized. Exercise training could therefore act as a tool to discover novel targets for heart failure treatment. We aimed to associate changes in Ca2+ handling and electrophysiology with micro-RNA (miRNA) profile in exercise trained heart failure rats to establish which miRNAs induce heart failure-like effects in Ca2+ handling and electrophysiology. METHODS AND RESULTS: Post-myocardial infarction (MI) heart failure was induced in Sprague Dawley rats. Rats with MI were randomized to sedentary control (sed), moderate (mod)- or high-intensity (high) endurance training for 8 weeks. Exercise training improved cardiac function, Ca2+ handling and electrophysiology including reduced susceptibility to arrhythmia in an exercise intensity-dependent manner where high intensity gave a larger effect. Fifty-five miRNAs were significantly regulated (up or down) in MI-sed, of which 18 and 3 were changed towards Sham-sed in MI-high and MI-mod, respectively. Thereafter we experimentally altered expression of these "exercise-miRNAs" individually in human induced pluripotent stem cell-derived cardiomyocytes (hIPSC-CM) in the same direction as they were changed in MI. Of the "exercise-miRNAs", miR-214-3p prolonged AP duration, whereas miR-140 and miR-208a shortened AP duration. miR-497-5p prolonged Ca2+ release whereas miR-214-3p and miR-31a-5p prolonged Ca2+ decay. CONCLUSION: Using exercise training as a tool, we discovered that miR-214-3p, miR-497-5p, miR-31a-5p contribute to heart-failure like behaviour in Ca2+ handling and electrophysiology and could be potential treatment targets.

Compliance With a National Standard by Norwegian Helicopter Emergency Physicians.

OBJECTIVE: The "National Standard Requirements for Helicopter Emergency Medicine Services Physicians" gives recommendations on medical requirements for flight physicians. This study describes the level of formal competence, experience, and guideline compliance of Norwegian helicopter emergency medical service (HEMS) physicians. METHODS: In May 2013, all HEMS physicians with full-time engagement at Norwegian HEMS bases were invited to participate in a cross-sectional survey using a structured, Web-based questionnaire. RESULTS: A total of 108 (79%) of 136 physicians replied to the survey, and all bases were represented. The majority (89%) had specialist training, and more than 60% had longer than 6 years of experience as a flight physician. Over 60% had attended trauma, pediatric, and incubator courses, and all physicians worked regularly in an anesthesia department. Most physicians were participating in simulation and procedure training. CONCLUSION: Many of the basic requirements of the guidelines were met by HEMS physicians, but room exists for improvements. Norwegian HEMS physicians are experienced, but a need exists for a more structured curriculum in emergency medicine for HEMS physicians based on the broad spectrum of presented medical conditions to ensure optimal quality of care and safety for all patients in Norway.

On predicting time to completion for the first stage of spontaneous labor at term in multiparous women.

BACKGROUND: Labor that progresses faster than anticipated may lead to unplanned out-of-hospital births. With the aim to improve planning of transportation to birthing institutions, this study investigated predictors of time to completion for the first stage of labor conditional on cervical opening (conditional time) in multiparous women at term. METHODS: We performed a retrospective analysis of partograms for women in Robson's group 3 who delivered at one hospital from 2003 to 2013. A generalized additive mixed model was fitted, accounting for possible non-linear relationships between the predictor variables and outcome, e.g. the time from each cervical measurement to full dilation, using multiple measurements for each woman. The following predictors were included: cervical dilation (cm), parity (1, 2, or ≥3 previous vaginal births), oxytocin infusion (no/yes), epidural (no/yes), maternal age (years), maternal height (cm), body mass index (BMI, kg/m2), birthweight (kg), spontaneous rupture of membranes (no/yes). A modified regression model with gestational age (days) instead of birthweight was used to predict conditional time to full cervical dilation for combinations of the most relevant predictors. RESULTS: A total of 1753 partograms were included in the analysis. The strongest predictors were birthweight, epidural and oxytocin use, and spontaneous rupture of membranes, along with cervical measurements. For birthweight, there was an almost 40% increase in time to full cervical dilation for each 1-kg increment. Conditional time was on average 23% longer in cases with epidural use and 53% longer in cases requiring oxytocin augmentation. Spontaneous rupture of the membranes shortened conditional time by 31%. Maternal age was not associated with the outcome, while increasing BMI and parity modestly reduced conditional time. CONCLUSIONS: Higher parity, lower fetal weight (gestational age), and spontaneous rupture of the membranes are associated with more rapid labor.

Why babies die in unplanned out-of-institution births: an enquiry into perinatal deaths in Norway 1999-2013.

INTRODUCTION: The aims were to describe causes of death associated with unplanned out-of-institution births, and to study whether they could be prevented. MATERIAL AND METHODS: Retrospective population-based observational study based on data from the Medical Birth Registry of Norway and medical records. Between 1 January 1999 and 31 December 2013, 69 perinatal deaths among 6027 unplanned out-of-institution births, whether unplanned at home, during transportation, or unspecified, were selected for enquiry. Hospital records were investigated and cases classified according to Causes of Death and Associated Conditions. RESULTS: 63 cases were reviewed. There were 25 (40%) antepartum deaths, 10 (16%) intrapartum deaths, and 24 neonatal (38%) deaths. Four cases were in the unknown death category (6%). Both gestational age and birthweight followed a bimodal distribution with modes at 24 and 38 weeks and 750 and 3400 g, respectively. The most common main cause of death was infection (n = 14, 22%), neonatal (n = 14, 22%, nine due to extreme prematurity) and placental (n = 12, 19%, seven placental abruptions). There were 86 associated conditions, most commonly perinatal (n = 32), placental (n = 15) and maternal (n = 14). Further classification revealed that the largest subgroup was associated perinatal conditions/sub-optimal care, involving 25 cases (40%), most commonly due to sub-optimal maternal use of available care (n = 14, 22%). CONCLUSIONS: Infections, neonatal, and placental causes accounted for almost two-thirds of perinatal mortality associated with unplanned out-of-institution births in Norway. Sub-optimal maternal use of available care was found in more than one-fifth of cases.

Intracranial Pressure During Pressure Control and Pressure-Regulated Volume Control Ventilation in Patients with Traumatic Brain Injury: A Randomized Crossover trial.

INTRODUCTION: Mechanical ventilation with control of partial arterial CO2 pressures (PaCO2) is used to treat or stabilize intracranial pressure (ICP) in patients with traumatic brain injury (TBI). Pressure-regulated volume control (PRVC) is a ventilator mode where inspiratory pressures are automatically adjusted to deliver the patient a pre-set stable tidal volume (TV). This may result in a more stable PaCO2 and thus a more stable ICP compared with conventional pressure control (PC) ventilation. The aim of this study was to compare PC and PRVC ventilation in TBI patients with respect to ICP and PaCO2. METHODS: This is a randomized crossover trial including eleven patients with a moderate or severe TBI who were mechanically ventilated and had ICP monitoring. Each patient was administered alternating 2-h periods of PC and PRVC ventilation. The outcome variables were ICP and PaCO2. RESULTS: Fifty-two (26 PC, 26 PRVC) study periods were included. Mean ICP was 10.8 mmHg with PC and 10.3 mmHg with PRVC ventilation (p = 0.38). Mean PaCO2 was 36.5 mmHg (4.87 kPa) with PC and 36.1 mmHg (4.81 kPa) with PRVC (p = 0.38). There were less fluctuations in ICP (p = 0.02) and PaCO2 (p = 0.05) with PRVC ventilation. CONCLUSIONS: Mean ICP and PaCO2 were similar for PC and PRVC ventilation in TBI patients, but PRVC ventilation resulted in less fluctuation in both ICP and PaCO2. We cannot exclude that the two ventilatory modes would have impact on ICP in patients with higher ICP values; however, the similar PaCO2 observations argue against this.

Effect of proton pump inhibitors on the serum concentrations of the selective serotonin reuptake inhibitors citalopram, escitalopram, and sertraline.

BACKGROUND: The selective serotonin reuptake inhibitors (SSRIs) citalopram, escitalopram, and sertraline are all metabolized by the cytochrome P-450 isoenzyme CYP2C19, which is inhibited by the proton pump inhibitors (PPIs) omeprazole, esomeprazole, lansoprazole, and pantoprazole. The aim of the present study was to evaluate the effect of these PPIs on the serum concentrations of citalopram, escitalopram, and sertraline. METHODS: Serum concentrations from patients treated with citalopram, escitalopram, or sertraline were obtained from a routine therapeutic drug monitoring database, and samples from subjects concomitantly using PPIs were identified. Dose-adjusted SSRI serum concentrations were calculated to compare data from those treated and those not treated with PPIs. RESULTS: Citalopram concentrations were significantly higher in patients treated with omeprazole (+35.3%; P < 0.001), esomeprazole (+32.8%; P < 0.001), and lansoprazole (+14.7%; P = 0.043). Escitalopram concentrations were significantly higher in patients treated with omeprazole (+93.9%; P < 0.001), esomeprazole (+81.8%; P < 0.001), lansoprazole (+20.1%; P = 0.008), and pantoprazole (+21.6%; P = 0.002). Sertraline concentrations were significantly higher in patients treated with esomeprazole (+38.5%; P = 0.0014). CONCLUSIONS: The effect of comedication with PPIs on the serum concentration of SSRIs is more pronounced for omeprazole and esomeprazole than for lansoprazole and pantoprazole, and escitalopram is affected to a greater extent than are citalopram and sertraline. When omeprazole or esomeprazole are used in combination with escitalopram, a 50% dose reduction of the latter should be considered.

Blood flow imaging in transesophageal echocardiography during atrial septal defect closure: a comparison with the current references.

BACKGROUND: Flow visualization before transcatheter atrial septal defect (ASD) closure is essential to identify the number and size of ASDs and to map the pulmonary veins (PV). Previous reports have shown improved visualization of ASD and PV using blood flow imaging (BFI), which supplements color Doppler imaging (CDI) with angle-independent information of flow direction. In this study, we compared transesophageal BFI with the current references in ASD sizing (balloon stretched diameter, BSD) and PV imaging (pulmonary angiography). METHODS: In this prospective study, 28 children were examined with transesophageal echocardiography (TEE) including BFI of the secundum ASD and the PV before interventional ASD closure. The maximum ASD diameter measured with BFI by 4 observers was compared to the corresponding BSD and CDI measurements. The repeatability of the BFI measurements was calculated as the residual standard deviation. BFI of the PV was compared to PV angiography. RESULTS: The mean maximum diameter measured by BFI was 12.1 mm (±SD 2.4 mm). The corresponding BSD and CDI measurements were 15.9 mm (±SD 3.0 mm) and 11.8 mm (±SD 2.5 mm), respectively. The residual standard deviation was 1.2 mm. Compared to PV angiography, the sensitivity of BFI in detecting the correct entry of the PV was 0.96 (95% CI: 0.82-1.0). CONCLUSION: Transesohageal echocardiography with BFI of the PV agreed well with pulmonary angiography. BFI had lower estimates for ASD size than BSD, but with acceptable 95% limits of agreement. The repeatability of the BFI measurements was close to the inherent ultrasound measurement error.

The Precision of Pulmonary Artery Catheter Bolus Thermodilution Cardiac Output Measurements Varies With the Clinical Situation.

OBJECTIVE: To investigate the effects of ventilatory mode, injectate temperature, and clinical situation on the precision of cardiac output measurements. DESIGN: Randomized, prospective observational study. SETTING: Single university hospital. PARTICIPANTS: Forty patients undergoing planned cardiac surgery, receiving a pulmonary artery catheter according to institutional routine. INTERVENTIONS: Cardiac output was measured at 4 predefined time points during the perioperative patient course, twice during controlled and twice during spontaneous ventilation, using 2 blocks of 8 measurement replications with cold and tepid injectate in random order. MEASUREMENTS AND MAIN RESULTS: The data were analyzed using a hierarchical linear mixed model. Clinical precision was determined as half the width of the 95% confidence interval for the underlying true value. The single-measurement precision measured in 2 different clinical situations for each temperature/ventilation combination was 8% to 10%, 11% to 13%, 13% to 15%, and 23% to 24% in controlled ventilation with cold injectate, controlled ventilation with tepid injectate, spontaneous breathing with cold injectate, and spontaneous breathing with tepid injectate, respectively. Tables are provided for the number of replications needed to achieve a certain precision and for how to identify significant changes in cardiac output. CONCLUSIONS: Clinical precision of cardiac output measurements is reduced significantly during spontaneous relative to controlled ventilation. The differences in precision between repeated measurement series within the temperature/ventilation combinations indicate influence of other situation-specific factors not related to ventilatory mode. Compared with tepid injectate in patients breathing spontaneously, the precision is 3-fold better with cold injectate and controlled ventilation.

Characteristics and outcome of unplanned out-of-institution births in Norway from 1999 to 2013: a cross-sectional study.

OBJECTIVE: To study the incidence, maternal characteristics and outcome of unplanned out-of-institution births (= unplanned births) in Norway. DESIGN: Register-based cross-sectional study. POPULATION: All births in Norway (n = 892 137) from 1999 to 2013 with gestational age ≥22 weeks. METHODS: Analysis of data from the Medical Birth Registry of Norway from 1999 to 2013. Unplanned births (n = 6062) were compared with all other births (reference group). RESULTS: The annual incidence rate of unplanned births was 6.8/1000 births and remained stable during the period of study. Young multiparous women residing in remote municipalities were at the highest risk of experiencing unplanned births. The unplanned birth group had higher perinatal mortality rate for the period, 11.4/1000 compared with 4.9/1000 for the reference group (incidence rate ratio 2.31, 95% confidence interval 1.82-2.93, p < 0.001). Annual perinatal mortality rate for unplanned births did not change significantly (p = 0.80) but declined on average by 3% per year in the reference group (p < 0.001). The unplanned birth group had a lower proportion of live births in all birthweight categories. Live born neonates with a birthweight of 750-999 g in the unplanned birth group had a more than five times higher mortality rate during the first week of life, compared with reference births in the same birthweight category. CONCLUSIONS: Unplanned births are associated with adverse outcome. Excessive mortality is possibly caused by reduced availability of necessary medical interventions for vulnerable newborns out-of-hospital.

Extracting physiologic and clinical data from defibrillators for research purposes to improve treatment for patients in cardiac arrest.

Background: A defibrillator should be connected to all patients receiving cardiopulmonary resuscitation (CPR) to allow early defibrillation. The defibrillator will collect signal data such as the electrocardiogram (ECG), thoracic impedance and end-tidal CO2, which allows for research on how patients demonstrate different responses to CPR. The aim of this review is to give an overview of methodological challenges and opportunities in using defibrillator data for research. Methods: The successful collection of defibrillator files has several challenges. There is no scientific standard on how to store such data, which have resulted in several proprietary industrial solutions. The data needs to be exported to a software environment where signal filtering and classifications of ECG rhythms can be performed. This may be automated using different algorithms and artificial intelligence (AI). The patient can be classified being in ventricular fibrillation or -tachycardia, asystole, pulseless electrical activity or having obtained return of spontaneous circulation. How this dynamic response is time-dependent and related to covariates can be handled in several ways. These include Aalen's linear model, Weibull regression and joint models. Conclusions: The vast amount of signal data from defibrillator represents promising opportunities for the use of AI and statistical analysis to assess patient response to CPR. This may provide an epidemiologic basis to improve resuscitation guidelines and give more individualized care. We suggest that an international working party is initiated to facilitate a discussion on how open formats for defibrillator data can be accomplished, that obligates industrial partners to further develop their current technological solutions.

Machine learning model to predict evolution of pulseless electrical activity during in-hospital cardiac arrest.

Background: During pulseless electrical activity (PEA) the cardiac mechanical and electrical functions are dissociated, a phenomenon occurring in 25-42% of in-hospital cardiac arrest (IHCA) cases. Accurate evaluation of the likelihood of a PEA patient transitioning to return of spontaneous circulation (ROSC) may be vital for the successful resuscitation. The aim: We sought to develop a model to automatically discriminate between PEA rhythms with favorable and unfavorable evolution to ROSC. Methods: A dataset of 190 patients, 120 with ROSC, were acquired with defibrillators from different vendors in three hospitals. The ECG and the transthoracic impedance (TTI) signal were processed to compute 16 waveform features. Logistic regression models where designed integrating both automated features and characteristics annotated in the QRS to identify PEAs with better prognosis leading to ROSC. Cross validation techniques were applied, both patient-specific and stratified, to evaluate the performance of the algorithm. Results: The best model consisted in a three feature algorithm that exhibited median (interquartile range) Area Under the Curve/Balanced accuracy/Sensitivity/Specificity of 80.3(9.9)/75.6(8.0)/ 77.4(15.2)/72.3(16.4) %, respectively. Conclusions: Information hidden in the waveforms of the ECG and TTI signals, along with QRS complex features, can predict the progression of PEA. Automated methods as the one proposed in this study, could contribute to assist in the targeted treatment of PEA in IHCA.

New, simplified versus standard photodynamic therapy (PDT) regimen for superficial and nodular basal cell carcinoma (BCC): A single-blind, non-inferiority, randomised controlled multicentre study.

BACKGROUND: Topical photodynamic therapy (PDT) is an approved and widely used treatment for low-risk basal cell carcinoma (BCC), comprising two sessions with an interval of 1 week. Simplification of the treatment course can be cost-effective, easier to organize, and cause less discomfort for the patients. METHODS AND FINDINGS: We performed an investigator-initiated, single-blind, non-inferiority, randomized controlled multicentre study with the objective of investigating whether a simpler and more flexible PDT regimen was not >10% less effective than the standard double PDT in the treatment of primary, superficial, and nodular ≤2 mm-thick BCC and evaluate the cosmetic outcome. With a non-inferiority margin of 0.1 and an expected probability complete response of 0.85, 190 tumours were required in each group. Histologically verified BCCs from seven centres in Norway were randomly assigned (1:1) to either receive a new regimen of single PDT with one possible re-treatment of non-complete responding tumours, or the standard regimen. The primary endpoint was the number of tumours with complete response or treatment failure at 36 months of follow-up, assessed by investigators blinded to the treatment regimen. Intention-to-treat and per-protocol analyses were performed. The cosmetic outcome was recorded. The study was registered with ClinicalTrials.gov, NCT-01482104, and EudraCT, 2011-004797-28. A total of 402 BCCs in 246 patients were included; 209 tumours assigned to the new and 193 to the standard regimen. After 36 months, there were 61 treatment failures with the new and 34 failures with the standard regimen. Complete response rate was 69.5% in the new and 81.1% in the standard treatment group. The difference was 11.6% (upper 97.5% CI 20.3), i.e. > than the non-inferiority margin of 10%. Cosmetic outcomes were excellent or good in 92% and 89% following the new and standard regimens, respectively. CONCLUSIONS: Single PDT with possible re-treatment of primary, superficial, and nodular ≤ 2-mm-thick BCC was significantly less effective than the approved standard double treatment. The cosmetic outcome was favorable and comparable between the two treatment groups.

Real-time feedback on chest compression efficacy by hands-free carotid Doppler in a porcine model.

Aim: Current guidelines for cardiopulmonary resuscitation (CPR) recommend a one-size-fits-all approach in relation to the positioning of chest compressions. We recently developed RescueDoppler, a hands-free Doppler ultrasound device for continuous monitoring of carotid blood flow velocity during CPR. The aim of the present study is to investigate whether RescueDoppler via real-time hemodynamic feedback, could identify both optimal and suboptimal compression positions. Methods: In this model of animal cardiac arrest, we induced ventricular fibrillation in five domestic pigs. Manual chest compressions were performed for ten seconds at three different positions on the sternum in random order and repeated six times. We analysed Time Average Velocity (TAV) with chest compression position as a fixed effect and animal, position, and sequential time within animals as random effects. Furthermore, we compared TAV to invasive blood pressure from the contralateral carotid artery. Results: We were able to detect changes in TAV when altering positions. The positions with the highest (range 19 to 48 cm/s) and lowest (6-25 cm/s) TAV were identified in all animals, with corresponding peak pressure 50-81 mmHg, and 46-64 mmHg, respectively. Blood flow velocity was, on average, highest at the middle position (TAV 33 cm/s), but with significant variability between animals (SD 2.8) and positions within the same animal (SD 9.3). Conclusion: RescueDoppler detected TAV changes during CPR with alternating chest compression positions, identifying the position yielding maximal TAV. Future clinical studies should investigate if RescueDoppler can be used as a real-time hemodynamical feedback device to guide compression position.

Out-of-hospital cardiac arrest in children in Norway: A national cohort study, 2016-2021.

Aim: Children constitute an important and distinct subgroup of out-of-hospital cardiac arrest (OHCA) patients. This population-based cohort study aims to establish current age-specific population incidence, precipitating causes, circumstances, and outcome of paediatric OHCA, to guide a focused approach to prevention and intervention to improve outcomes. Methods: Data from the national Norwegian Cardiac Arrest Registry was extracted for the six-year period 2016-21 for persons aged <18 years. We present descriptive statistics for the population, resuscitation events, presumed causes, treatment, and outcomes, alongside age-specific incidence and total paediatric mortality rates. Results: Three hundred and eight children were included. The incidence of OHCA was 4.6 per 100 000 child-years and markedly higher in children <1 year at 20.9 child-years. Leading causes were choking, cardiac and respiratory disease, and sudden infant death syndrome. Overall, 21% survived to 30 days and 18% to one year. Conclusion: A registry-based approach enabled this study to delineate the characteristics and trajectories of OHCA events in a national cohort of children. Precipitating causes of paediatric OHCA are diverse compared to adults. Infants aged <1 year are at particularly high risk. Mortality is high, albeit lower than for adults in Norway. A rational community approach to prevention and treatment may focus on general infant care, immediate first aid by caretakers, and identification of vulnerable children by primary health providers. Cardiac arrest registries are a key source of knowledge essential for quality improvement and research into cardiac arrest in childhood.

Hands-free continuous carotid Doppler ultrasound for detection of the pulse during cardiac arrest in a porcine model.

Background/Purpose: Pulse palpation is an unreliable method for diagnosing cardiac arrest. To address this limitation, continuous hemodynamic monitoring may be a viable solution. Therefore, we developed a novel, hands-free Doppler system, RescueDoppler, to detect the pulse continuously in the carotid artery. Methods: In twelve pigs, we evaluated RescueDopplers potential to measure blood flow velocity in three situations where pulse palpation of the carotid artery was insufficient: (1) systolic blood pressure below 60 mmHg, (2) ventricular fibrillation (VF) and (3) pulseless electrical activity (PEA). (1) Low blood pressure was induced using a Fogarty balloon catheter to occlude the inferior vena cava. (2) An implantable cardioverter-defibrillator induced VF. (3) Myocardial infarction after microembolization of the left coronary artery caused True-PEA. Invasive blood pressure was measured in the contralateral carotid artery. Time-averaged blood flow velocity (TAV) in the carotid artery was related to mean arterial pressure (MAP) in a linear mixed model. Results: RescueDoppler identified pulsatile blood flow in 41/41 events with systolic blood pressure below 60 mmHg, with lowest blood pressure of 19 mmHg. In addition the absence of spontaneous circulation was identified in 21/21 VF events and true PEA in 2/2 events. The intraclass correlation coefficient within animals for TAV and MAP was 0.94 (95% CI. 0.85-0.98). Conclusions: In a porcine model, RescueDoppler reliably identified pulsative blood flow with blood pressures below 60 mmHg. During VF and PEA, circulatory arrest was rapidly and accurately demonstrated. RescueDoppler could potentially replace unreliable pulse palpation during cardiac arrest and cardiopulmonary resuscitation.