Erik Alonso

• PhD
• Professor at University of the Basque Country

Load distributing band (LDB) mechanical chest compression (CC) devices are used to treat out-of-hospital cardiac arrest (OHCA) patients. Mechanical CCs induce artifacts in the electrocardiogram (ECG) recorded by defibrillators, potentially leading to inaccurate cardiac rhythm analysis. A reliable analysis of the cardiac rhythm is essential for guid...

Objective To develop and validate a paediatric weight estimation model adapted to the characteristics of the Spanish population as an alternative to currently extended methods. Methods Anthropometric data in a cohort of 11 287 children were used to develop machine learning models to predict weight using height and the body mass index (BMI) quartil...

Load Distributing Band (LDB) mechanical chest compression (CC) device is used to treat out-of-hospital cardiac arrest (OHCA) patients. Mechanical CCs induce artifacts in the electrocardiogram (ECG) recorded by defibrillators, potentially leading to inaccurate cardiac rhythm analysis. A reliable analysis of the cardiac rhythm is essential for guidin...

Background: While early vasopressor administration (epinephrine, vasopressin) and early advanced airway management (laryngeal tube [LT], endotracheal intubation [ETI]) have been associated with improved outcomes after out-of-hospital cardiac arrest (OHCA), their optimal sequence during resuscitation remains unclear. Aims: To determine the associati...

Background This study aimed to evaluate three prehospital early warning scores (EWSs): RTS, MGAP and MREMS, to predict short-term mortality in acute life-threatening trauma and injury/illness by comparing United States (US) and Spanish cohorts. Methods A total of 8,854 patients, 8,598/256 survivors/nonsurvivors, comprised the unified cohort. Datas...

There is no reliable automated non-invasive solution for monitoring circulation and guiding treatment in prehospital emergency medicine. Cardiac output (CO) monitoring might provide a solution, but CO monitors are not feasible/practical in the prehospital setting. Non-invasive ballistocardiography (BCG) measures heart contractility and tracks CO ch...

Objective: Ventilation control is important during resuscitation from out-of-hospital cardiac arrest (OHCA). We compared different methods for calculating ventilation rates (VR) during OHCA. Methods: We analyzed data from the Pragmatic Airway Resuscitation Trial, identifying ventilations through capnogram recordings. We determined VR by: 1) coun...

Introduction: Cardiac arrest resuscitation guidelines recommend optimization of both chest compression rate (CCR) and fraction (CCF). Simultaneous management of CCR and CCF is challenging. The interaction between CCR and CCF is unknown. Our objective was to evaluate the influence of CCR, CCF and their interactions upon OHCA 72-hour survival. Method...

Background We sought to describe ventilation rates during out-of-hospital cardiac arrest (OHCA) resuscitation and their associations with airway management strategy and outcomes. Methods We analyzed continuous end-tidal carbon dioxide capnography data from adult OHCA enrolled in the Pragmatic Airway Resuscitation Trial (PART). Using automated sign...

Background Out-of-hospital cardiac arrest (OHCA) data debriefing and clinical research often require the retrospective analysis of large datasets containing defibrillator files from different vendors and clinical annotations by the emergency medical services. Aim To introduce and evaluate a methodology to automatically extract cardiopulmonary resu...

BACKGROUND Chest compression (CC) quality is associated with improved out-of-hospital cardiopulmonary arrest (OHCA) outcomes. Airway management efforts may adversely influence CC quality. We sought to compare the effects of initial laryngeal tube (LT) and initial endotracheal intubation (ETI) airway management strategies upon chest compression frac...

The availability of an automatic pulse detection during out-of-hospital cardiac arrest (OHCA) would allow the rapid identification of cardiac arrest and the prompt detection of return of spontaneous circulation. The aim of this study was to develop a reliable pulse detection algorithm using the electrocardiogram (ECG) and thoracic impedance (TI), t...

Introduction: In out-of-hospital cardiac arrest (OHCA) a reliable rhythm diagnosis by the automated external defibrillator (AED) allows for the delivery of correct therapy, a prompt defibrillation for shockable rhythms and resuming cardiopulmonary resuscitation for non-shockable rhythms. The aim of this study was to develop a machine-learning (ML)...

Introduction: Pulse detection during out-of-hospital cardiac arrest (OHCA) is a challenge still not satisfactorily solved. An automated and accurate method for detecting pulse would reduce hands-off intervals and allow for more prompt post-cardiac arrest care. The aim of this study was to develop a method based on machine learning (ML) to detect pu...

Pulse detection during out-of-hospital cardiac arrest remains challenging for both novel and expert rescuers because current methods are inaccurate and time-consuming. There is still a need to develop automatic methods for pulse detection, where the most challenging scenario is the discrimination between pulsed rhythms (PR, pulse) and pulseless ele...

Monitoring ventilation rate is key to improve the quality of cardiopulmonary resuscitation (CPR) and increase the probability of survival in the event of an out-of-hospital cardiac arrest (OHCA). Ventilations produce discernible fluctuations in the thoracic impedance signal recorded by defibrillators. Impedance-based detection of ventilations durin...

Background: Automated detection of return of spontaneous circulation (ROSC) is still an unsolved problem during cardiac arrest. Current guidelines recommend the use of capnography, but most automatic methods are based on the analysis of the ECG and thoracic impedance (TI) signals. This study analysed the added value of EtCO2 for discriminating pul...

The automatic detection of pulse during out-of-hospital cardiac arrest (OHCA) is necessary for the early recognition of the arrest and the detection of return of spontaneous circulation (end of the arrest). The only signal available in every single defibrillator and valid for the detection of pulse is the electrocardiogram (ECG). In this study we p...

Goal: Accurate shock decision methods during piston-driven cardiopulmonary resuscitation (CPR) would contribute to improve therapy and increase cardiac arrest survival rates. The best current methods are computationally demanding, and their accuracy could be improved. The objective of this work was to introduce a computationally efficient algorith...

Sudden cardiac arrest is one of the leading causes of death in the industrialized world. Pulse detection is essential for the recognition of the arrest and the recognition of return of spontaneous circulation during therapy, and it is therefore crucial for the survival of the patient. This paper introduces the first method based exclusively on the...

Objective: An accurate rhythm analysis during cardiopulmonary resuscitation (CPR) would contribute to increase survival from out-of-hospital cardiac arrest. Piston-driven mechanical compression devices are frequently used to deliver CPR. The objective of this work was to design a method to accurately diagnose the rhythm during compressions deliver...

Aim: To evaluate the performance of a state-of-the-art cardiopulmonary resuscitation (CPR) artefact suppression method by assessing to what extent the filtered electrocardiogram (ECG) can be correctly diagnosed by emergency medicine doctors. Methods: A total of 819 ECG segments were used. Each segment contained two consecutive 10s intervals, an...

This study was conceived to analyze the possibility of monitoring the respiratory rate using oximetry signals obtained via Near-InfraRed Spectroscopy (NIRS) in the forehead, and to compare the results to those obtained using the photoplethysmography (PPG) signal. 29 subjects were enrolled in 30 min recording sessions at three controlled respiration...

Cerebral oximetry of the frontal lobes based on Near InfraRed Spectroscopy (NIRS) is used to monitor brain tissue oxygen saturation in 2–4 s intervals. However, higher sampling rates may enable heart rate (HR) monitoring. In total, 29 subjects were enrolled in 40 min recording sessions. Cerebral oxy-haemoglobin (O 2 Hb) concentration at 50 Hz and t...

Aim: The rates of chest compressions (CCs) and ventilations are both important metrics to monitor the quality of cardiopulmonary resuscitation (CPR). Capnography permits monitoring ventilation, but the CCs provided during CPR corrupt the capnogram and compromise the accuracy of automatic ventilation detectors. The aim of this study was to evaluate...

Aim: To develop and evaluate a method to detect circulation in the presence of organized rhythms (ORs) during resuscitation using signals acquired by defibrillation pads. Methods: Segments containing electrocardiogram (ECG) and thoracic impedance (TI) signals free of artifacts were used. The ECG corresponded to ORs classified as pulseless electr...

The survival rate in cardiac arrest is associated to the quality of the chest compressions (CCs) and ventilations provided during cardiopulmonary resuscitation (CPR). Hyperventilation remains common whenever ventilation is manual during resuscitation from cardiac arrest. The capnogram is used to monitor respiration and ventilation rates. During CPR...

Quality of cardiopulmonary resuscitation (CPR) is an important determinant of survival from cardiac arrest. The use of feedback devices is encouraged by current resuscitation guidelines as it helps rescuers to improve quality of CPR performance. To determine the feasibility of a generic algorithm for feedback related to chest compression (CC) rate...

Aim: Chest compression artefacts impede a reliable rhythm analysis during cardiopulmonary resuscitation (CPR). These artefacts are not present during ventilations in 30:2 CPR. The aim of this study is to prove that a fully automatic method for rhythm analysis during ventilation pauses in 30:2 CPR is reliable an accurate. Methods: For this study 141...

To determine the accuracy and reliability of the thoracic impedance (TI) signal to assess cardiopulmonary resuscitation (CPR) quality metrics. A dataset of 63 out-of-hospital cardiac arrest episodes containing the compression depth (CD), capnography and TI signals was used. We developed a chest compression (CC) and ventilation detector based on the...

Background: During resuscitation, checking for a carotid pulse to recognize cardiac arrest or detect the return of spontaneous circulation (ROSC) has been shown to be both inaccurate and time-consuming. More recently, an abrupt sustained increase in end-tidal carbon dioxide (EtCO2) to a normal value (35 to 40 mmHg) has been accepted as an indicator...

Cardiopulmonary resuscitation (CPR) artifact filtering techniques have not been successfully combined with commercial shock advice algorithms (SAA) to diagnose the rhythm during CPR. Recently, a promising new approach based on using SAAs especially designed to diagnose the filtered ECG has been introduced. This study evaluates the impact of filteri...

Aim: To propose a method which analyses the electrocardiogram (ECG) waveform of any cardiac rhythm occurring during resuscitation and computes the probability of that rhythm converting into another with better prognosis (Pdes). Methods: Rhythm transitions occurring spontaneously or due to defibrillation were analyzed. For each possible rhythm, v...

Quality of cardiopulmonary resuscitation (CPR) improves through the use of CPR feedback devices. Most feedback devices integrate the acceleration twice to estimate compression depth. However, they use additional sensors or processing techniques to compensate for large displacement drifts caused by integration. This study introduces an accelerometer...

Interruptions in cardiopulmonary resuscitation (CPR) compromise defibrillation success. However, CPR must be interrupted to analyze the rhythm because although current methods for rhythm analysis during CPR have high sensitivity for shockable rhythms, the specificity for nonshockable rhythms is still too low. This paper introduces a new approach to...

Aim: Hyperventilation, frequent during cardiopulmonary resuscitation (CPR), decreases cerebral and coronary perfusion contributing to poorer survival rates in both animals and humans. The 2010 resuscitation guidelines recommend continuous monitoring of the exhaled carbon dioxide (CO2) during CPR. The capnogram shows fluctuations caused by ventilati...

Accurate chest compression detection is key to evaluate cardiopulmonary resuscitation (CPR) quality. Two automatic compression detectors were developed, for the compression depth (CD), and for the thoracic impedance (TI). The objective was to evaluate their accuracy for compression detection and for CPR quality assessment. Compressions were manuall...

To analyze the relationship between the depth of the chest compressions and the fluctuation caused in the thoracic impedance (TI) signal in out-of-hospital cardiac arrest (OHCA). The ultimate goal was to evaluate whether it is possible to identify compressions with inadequate depth using information of the TI waveform. 60 OHCA episodes were extract...

During cardiopulmonary resuscitation feedback systems can help rescuers to achieve optimal chest compression rates. In this paper we describe and compare two methods to provide chest compression rate feedback based only on the thoracic impedance signal, available in automatic external defibrillators. The first method (time domain) identified the re...

The thoracic impedance (TI) signal, which reflects fluctuations due to CCs and ventilations, has been suggested as a surrogate to compute CC–rate and ventilation–rate during cardiopulmonary resuscitation. This study developed a method based on empirical mode decomposition (EMD) to compute CC–rate and ventilation–rate using exclusively the TI. Twent...

Aim: To analyze the feasibility of extracting the circulation component from the thoracic impedance acquired by defibrillation pads. The impedance circulation component (ICC) would permit detection of pulse-generating rhythms (PRs) during the analysis intervals of an automated external defibrillator when a non-shockable rhythm with QRS complexes i...

Objectives: Filtering the cardiopulmonary resuscitation (CPR) artifact has been a major approach to minimizing interruptions to CPR for rhythm analysis. However, the effects of these filters on interruptions to CPR have not been evaluated. This study presents the first methodology for directly quantifying the effects of filtering on the uninterrup...

Aim: To demonstrate the feasibility of doing a reliable rhythm analysis in the chest compression pauses (e.g. pauses for two ventilations) during cardiopulmonary resuscitation (CPR). Methods: We extracted 110 shockable and 466 nonshockable segments from 235 out-of-hospital cardiac arrest episodes. Pauses in chest compressions were already annota...

The thoracic impedance (TI) signal, available in current automated external defibrillators, has been proposed as an indicator of the compression depth (CD) in animal models of cardiac arrest. This study analysed the linear relationship between the maximum CD and the fluctuation caused in the TI in 19 out-of-hospital cardiac arrest episodes. The mea...

During cardiopulmonary resuscitation, excessive ventilation rates decrease cardiac output, thus reducing the chance of survival. We have developed a simple method to automatically detect ventilations based on the analysis of the thoracic impedance signal recorded through defibrillation pads. We used 18 out-of hospital cardiac arrest episodes that c...

Rhythm analysis methods for shock advice during CPR are evaluated in terms of sensitivity and specificity. However, these figures do not convey the real impact that using these methods would have on the delivery of CPR. This study evaluates the impact on CPR delivery of a new rhythm analysis method.

To design the core algorithm of a high-temporal resolution rhythm analysis algorithm for automated external defibrillators (AEDs) valid for adults and children. Records from adult and paediatric patients were used all together to optimize and test the performance of the algorithm. A total of 574 shockable and 1126 nonshockable records from 1379 adu...

The recommended treatment for out-of-hospital cardiac arrest (OHCA) is immediate cardiopulmonary resuscitation (CPR) and early electrical defibrillation. During CPR, chest compressions and ventilations should be provided with a compression-ventilation ratio of 30:2. Chest compressions and ventilations induce fast and slow fluctuations, respectively...

Circulation detection by checking the carotid pulse in cardiac arrest patients during cardiopulmonary resuscitation (CPR) has been reported inaccurate. Thoracic impedance (TI) measured via the defibrillator pads has been recently proposed for the assessment of circulation during CPR. However, ventilation artefacts severely corrupt and spectrally ov...

A shock advice algorithm (SAA) that reliably diagnoses the rhythm during cardiopulmonary resuscitation (CPR) would avoid unnecessary CPR interruptions and increase the probability of a successful resuscitation. Current approaches based on filtering the CPR artifact from the ECG or analyzing the corrupted ECG do not meet the American Heart Associati...

To demonstrate that the instantaneous chest compression rate can be accurately estimated from the transthoracic impedance (TTI), and that this estimated rate can be used in a method to suppress cardiopulmonary resuscitation (CPR) artefacts. A database of 372 records, 87 shockable and 285 non-shockable, from out-of-hospital cardiac arrest episodes,...

A reliable diagnosis by automated external defibrillators (AED) during cardiopulmonary resuscitation (CPR) would reduce hands-off time, thus increasing the resuscitation success. Several filters based on one (dual-channel) or multiple (multi-channel) reference signals have been proposed to remove the artifact induced on the ECG by chest compression...

Diagnosis during cardiopulmonary resuscitation (CPR) is highly desirable because it has been reported to be determinant for a successful outcome from sudden cardiac arrest. This study evaluates the accuracy and the time-effect of applying CPR artefact suppression prior to rhythm classification with long out-of-hospital cardiac arrest episodes. A to...

Detection of Ventricular fibrillation (VF) in automated external defibrillators (AED) is tested following the recommendations of the American Heart Association (AHA). However, nonshockable out-of-hospital cardiac arrest (OHCA) rhythms may be very different from those covered in the AHA recommendations. In this study we compare the performance of fo...