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1.
Resuscitation ; 200: 110259, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38823474

RESUMO

BACKGROUND: Interpretation of end-tidal CO2 (ETCO2) during manual cardiopulmonary resuscitation (CPR) is affected by variations in ventilation and chest compressions. This study investigates the impact of standardising ETCO2 to constant ventilation rate (VR) and compression depth (CD) on absolute values and trends. METHODS: Retrospective study of out-of-hospital cardiac arrest cases with manual CPR, including defibrillator and clinical data. ETCO2, VR and CD values were averaged by minute. ETCO2 was standardised to 10 vpm and 50 mm. We compared standardised (ETs) and measured (ETm) values and trends during resuscitation. RESULTS: Of 1,036 cases, 287 met the inclusion criteria. VR was mostly lower than recommended, 8.8 vpm, and highly variable within and among patients. CD was mostly within guidelines, 49.8 mm, and less varied. ETs was lower than ETm by 7.3 mmHg. ETs emphasized differences by sex (22.4 females vs. 25.6 mmHg males), initial rhythm (29.1 shockable vs. 22.7 mmHg not), intubation type (25.6 supraglottic vs. 22.4 mmHg endotracheal) and return of spontaneous circulation (ROSC) achieved (34.5 mmHg) vs. not (20.1 mmHg). Trends were different between non-ROSC and ROSC patients before ROSC (-0.3 vs. + 0.2 mmHg/min), and between sustained and rearrest after ROSC (-0.7 vs. -2.1 mmHg/min). Peak ETs was higher for sustained than for rearrest (53.0 vs. 42.5 mmHg). CONCLUSION: Standardising ETCO2 eliminates effects of VR and CD variations during manual CPR and facilitates comparison of values and trends among and within patients. Its clinical application for guidance of resuscitation warrants further investigation.


Assuntos
Dióxido de Carbono , Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Humanos , Reanimação Cardiopulmonar/métodos , Reanimação Cardiopulmonar/normas , Masculino , Feminino , Estudos Retrospectivos , Parada Cardíaca Extra-Hospitalar/terapia , Pessoa de Meia-Idade , Dióxido de Carbono/análise , Idoso , Capnografia/métodos , Volume de Ventilação Pulmonar/fisiologia
2.
Heliyon ; 10(7): e28739, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38601572

RESUMO

Aim: Propose new metrics of impulsiveness of manual chest compressions (CCs) that account for shape and duration, separate the characteristics of the compressive part of the CC cycle from those of the recoil part, and are uncorrelated to CC depth and rate. Methods: We conducted a retrospective analysis of adult out-of-hospital cardiac arrest monitor-defibrillator recordings having CPR data. Specifically, episodes of adult patients with ≥ 1000 compressions free of leaning were examined. CCs were obtained from the depth signal of the valid episodes, and we calculated the novel metrics: compression area index (CAI), recoil area index (RAI), compression impulsiveness index (CII) and recoil impulsiveness index (RII). Generalized linear mixed-effects models and Jonckheere-Terpstra trend analyses were employed to measure differences between populations and trends, and the absolute value of Pearson's correlation coefficient |r| was used to report dependence between variables. Statistics are reported as median and interquartile range. Results: We analyzed 982,340 CCs corresponding to 453 episodes, for which we calculated their CAI, RAI and duty cycle (DC). We analyzed the metrics for various populations: age, sex, any ROSC achieved and disposition, and found that CAI was significantly different according to patient disposition and RAI relative to age and sex (p<0.05). None of the metrics was correlated strongly to depth or rate (|r| values of 0.22 or smaller), and all of them varied for CC series corresponding to the same rescuer over the course of resuscitation (ptrend<0.05). However, we observed that the metrics are not balanced, in that for any value of DC, CAI and RAI span almost their entire ranges. Conclusion: The proposed metrics correctly and completely describe manual CC waveforms, improve upon the DC, since they depend on the signal waveform, and provide additional information to current indicators of quality CPR, depth and rate. Furthermore, they allow to differentiate the compressive and recoil parts of the CC cycle, reflecting influence of the rescuer (via CAI or CII) and of the biomechanics of the patient's chest (via RAI or RII). Thus, they have the potential to contribute to better understanding CPR dynamics and, eventually, to enhanced quality of CPR practice as additional indicators of proper manual CC technique.

3.
Am J Emerg Med ; 31(6): 910-5, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23680330

RESUMO

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 uninterrupted CPR time. METHODS: A total of 241 shockable and 634 nonshockable out-of-hospital cardiac arrest records (median duration, 150 seconds) from 248 patients were analyzed. Filtering and rhythm analysis were commenced after 1 minute of CPR, and the end point for CPR was established at the time of the first shock diagnosis. Kaplan-Meier curves were used to compute the probability of interrupting CPR as a function of time. The probabilities of delivering 2 minutes of uninterrupted CPR for the shockable and nonshockable rhythms were compared with the 2-minute cycles of uninterrupted CPR recommended by the guidelines. RESULTS: For the nonshockable rhythms, the probabilities of delivering at least 2 and 3 minutes of uninterrupted CPR were 58% (95% confidence interval, 54%-62%) and 48% (44%-52%), respectively. These are the probabilities of reducing and substantially reducing the frequency of CPR interruptions for rhythm analysis. For the shockable rhythms, the probability of avoiding unnecessary CPR prolongation beyond 2 minutes was 100% (99%-100%). CONCLUSIONS: Filtering reduces the frequency of CPR interruptions for rhythm analysis in less than 60% of nonshockable rhythms. New strategies to increase the probability of prolonging CPR for nonshockable rhythms should be defined and evaluated using the methodology proposed in this study.


Assuntos
Reanimação Cardiopulmonar/estatística & dados numéricos , Cardioversão Elétrica/estatística & dados numéricos , Eletrocardiografia , Fidelidade a Diretrizes/estatística & dados numéricos , Massagem Cardíaca , Humanos , Estimativa de Kaplan-Meier , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Prospectivos , Fatores de Tempo
4.
Comput Methods Programs Biomed ; 242: 107847, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37852146

RESUMO

AIM: The purpose of this study was to develop a simple viscoelastic model to characterize the mechanical properties of chests during manual chest compressions in pre-hospital cardiopulmonary resuscitation (CPR). METHODS: Force and acceleration signals were extracted from CPR monitors used during pre-hospital resuscitation attempts on adult patients. Individual chest compressions were identified and segmented from the chest displacement computed using the force and acceleration. Each compression-recoil cycle was characterized by its elastic coefficient k (a measure of stiffness) and its compression and recoil damping coefficients, dc and dr, respectively (measures of viscosity). We compared the estimated and the calculated chest displacement to assess the goodness of fit of the model. We characterized the chest of patients at the beginning of CPR in relation to sex and age, and their variation as CPR progressed. RESULTS: A total of 1,156,608 chest compressions from 615 patients were analysed. Mean (95% CI) coefficient of determination R2 for the viscoelastic model was 97.9% (97.8-98.1). At the beginning of CPR, k was 104.9 N⋅cm-1 (102.0-107.8), dc was 2.868 N⋅s⋅cm-1 (2.751-2.984) and dr was 4.889 N⋅s⋅cm-1 (4.648-5.129). Damping during recoil was significantly higher than during compression. Stiffness was lower in women than in men. There were no differences in damping coefficients with sex but a higher dr with increasing age. All model coefficients decreased with compression count, with an overall decrease after 3,000 chest compressions of 34.6%, 48.8% and 37.2%, respectively. CONCLUSION: The model accurately described adult chest mechanical properties during CPR, highlighting differences between compression and recoil, sex and age, and a progressive reduction in chest stiffness and viscosity along resuscitation. Our findings may merit further investigation into whether patient-tailored and time-sensitive chest compression technique may be appropriate.


Assuntos
Reanimação Cardiopulmonar , Masculino , Humanos , Adulto , Feminino , Tórax , Pressão , Hospitais
5.
J Clin Med ; 12(21)2023 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-37959385

RESUMO

Background: There is growing interest in the quality of manual ventilation during cardiopulmonary resuscitation (CPR), but accurate assessment of ventilation parameters remains a challenge. Waveform capnography is currently the reference for monitoring ventilation rate in intubated patients, but fails to provide information on tidal volumes and inspiration-expiration timing. Moreover, the capnogram is often distorted when chest compressions (CCs) are performed during ventilation compromising its reliability during CPR. Our main purpose was to characterize manual ventilation during CPR and to assess how CCs may impact on ventilation quality. Methods: Retrospective analysis were performed of CPR recordings fromtwo databases of adult patients in cardiac arrest including capnogram, compression depth, and airway flow, pressure and volume signals. Using automated signal processing techniques followed by manual revision, individual ventilations were identified and ventilation parameters were measured. Oscillations on the capnogram plateau during CCs were characterized, and its correlation with compression depth and airway volume was assessed. Finally, we identified events of reversed airflow caused by CCs and their effect on volume and capnogram waveform. Results: Ventilation rates were higher than the recommended 10 breaths/min in 66.7% of the cases. Variability in ventilation rates correlated with the variability in tidal volumes and other ventilatory parameters. Oscillations caused by CCs on capnograms were of high amplitude (median above 74%) and were associated with low pseudo-volumes (median 26 mL). Correlation between the amplitude of those oscillations with either the CCs depth or the generated passive volumes was low, with correlation coefficients of -0.24 and 0.40, respectively. During inspiration and expiration, reversed airflow events caused opposed movement of gases in 80% of ventilations. Conclusions: Our study confirmed lack of adherence between measured ventilation rates and the guideline recommendations, and a substantial dispersion in manual ventilation parameters during CPR. Oscillations on the capnogram plateau caused by CCs did not correlate with compression depth or associated small tidal volumes. CCs caused reversed flow during inspiration, expiration and in the interval between ventilations, sufficient to generate volume changes and causing oscillations on capnogram. Further research is warranted to assess the impact of these findings on ventilation quality during CPR.

6.
Resuscitation ; 179: 225-232, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35835250

RESUMO

AIM: Characterise how changes in chest compression depth and rate affect variations in end-tidal CO2 (ETCO2) during manual cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA). METHODS: Retrospective analysis of adult OHCA monitor-defibrillator recordings having concurrent capnogram, compression depth, transthoracic impedance and ECG, and with atleast 1,000 compressions. Within each patient, during no spontaneous circulation, nearby segments with changes in chest compression depth and rate were identified. Average ETCO2 within each segment was standardised to compensate for ventilation rate variability. Contributions of relative variations in depth and rate to relative variations in standardised ETCO2 were characterised using linear and non-linear models. Normalisation between paired segments removed intra and inter-patient variation and made coefficients of the model independent of the scale of measurement and therefore directly comparable. RESULTS: A total of 394 pairs of segments from 221 patients were analysed (33% female, median (IQR) age 66 (55-74) years). Chest compression depth and rate were 50.4 (43.2-57.0)mm and 111.1 (106.5-116.1)compressions per minute. ETCO2 before and after standardization was 32.1 (23.0-41.4)mmHg and 28.5 (19.4-38.7)mmHg. Linear model coefficient of determination was 0.89. Variation in compression depth mainly explained ETCO2 variation (coefficient 0.95, 95% confidence interval (CI): 0.93-0.98) while changes in compression rate did not (coefficient 0.04, 95% CI: 0.01-0.07). Non-linear trend analysis confirmed the results. CONCLUSION: This study quantified the relative importance of chest compression characteristics in terms of their impact on CO2 production during CPR. With ventilation rate standardised, variation in chest compression depth explained variations in ETCO2 better than variation in chest compression rate.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Adulto , Idoso , Dióxido de Carbono/análise , Reanimação Cardiopulmonar/métodos , Feminino , Hospitais , Humanos , Masculino , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Retrospectivos
7.
Resuscitation ; 167: 180-187, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34461206

RESUMO

AIM OF THE STUDY: Characterize release and recoil dynamics in chest compressions during prolonged cardiopulmonary resuscitation (CPR) efforts, which are increasingly prevalent. METHODS: Force and depth of chest compressions, and their rates of change, were calculated from records extracted from CPR monitors used during prolonged resuscitation efforts for out-of-hospital cardiac arrest and tracked over time. Metrics were normalized to the median of the first 100 compressions. Kruskal-Wallis ANOVA and Jonckheere-Terpstra trend analyses were used for differences and trends. Averages are reported as median (interquartile range). Correlations among metrics are reported as coefficients of determination. RESULTS: In 471 cases of adult subjects receiving at least 1000 compressions, peak depths varied modestly over the course of extended resuscitation efforts, staying within a narrow range without a trend over the course of resuscitation efforts. Increases in recoil velocity and decreases in recoil interval also remained within limited ranges (5%, 6% variation respectively). By contrast, force waveforms changed substantially. Peak force decreased monotonically reaching a 38% decrease for compression numbers > 3500, similar to a decrease in release rate (39%) and an increase in release interval (39%). CONCLUSION: Depth waveforms change markedly less than do force waveforms over the course of prolonged CPR. With the benefit of feedback, CPR providers effectively adjust the application of force to compensate for changes in chest stiffness, documented previously. Despite slowing release and quickening recoil, interference between release of force and recoil of depth appears limited. Spontaneous chest recoil is well preserved in prolonged duration manual CPR.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Adulto , Retroalimentação , Humanos , Parada Cardíaca Extra-Hospitalar/terapia , Pressão , Tórax
8.
Resuscitation ; 162: 198-204, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33705805

RESUMO

AIM OF THE STUDY: To characterize the effects of extended duration continuous compressions cardiopulmonary resuscitation (CPR) on chest stiffness, and its association with adherence to CPR guidelines. METHODS: Records of force and acceleration were extracted from CPR monitors used during attempts of resuscitation from out-of-hospital cardiac arrest. Cases of patients receiving at least 1000 compressions were selected for analysis to focus on extended CPR efforts. Stiffness was normalized per patient to their initial stiffness. Force remaining at the end of compression was used to identify complete release. Non-parametric statistical methods were used throughout as underlying distributions of all types of measurements were non-Gaussian. Averages are reported as median (interquartile range). RESULTS: More than 1000 chest compressions were delivered in 471 of 703 cases. Rate of change in normalized stiffness (Sn) was unrelated to patient age, sex or initial ECG rhythm, and did not predict survival. Most (76%) chests became less stiff over the course of resuscitation efforts. While the remainder (24%) exhibited increased stiffness, overall Sn decreased monotonically, declining by 31% through 3500 compressions. Rate adherence did not show a consistent trend with Sn. Depth adherence and complete release improved modestly with decreasing Sn. CONCLUSION: Chest compressions during extended CPR reduced the stiffness of most patients' chests, in the aggregate by 31% after 3500 compressions. This softening was associated with modestly improved adherence to depth and release guidelines, with inconsistent relation to rate adherence to guidelines.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Humanos , Parada Cardíaca Extra-Hospitalar/terapia , Tórax
9.
PLoS One ; 16(5): e0251511, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34003839

RESUMO

BACKGROUND: Measurement of end-tidal CO2 (ETCO2) can help to monitor circulation during cardiopulmonary resuscitation (CPR). However, early detection of restoration of spontaneous circulation (ROSC) during CPR using waveform capnography remains a challenge. The aim of the study was to investigate if the assessment of ETCO2 variation during chest compression pauses could allow for ROSC detection. We hypothesized that a decay in ETCO2 during a compression pause indicates no ROSC while a constant or increasing ETCO2 indicates ROSC. METHODS: We conducted a retrospective analysis of adult out-of-hospital cardiac arrest (OHCA) episodes treated by the advanced life support (ALS). Continuous chest compressions and ventilations were provided manually. Segments of capnography signal during pauses in chest compressions were selected, including at least three ventilations and with durations less than 20 s. Segments were classified as ROSC or non-ROSC according to case chart annotation and examination of the ECG and transthoracic impedance signals. The percentage variation of ETCO2 between consecutive ventilations was computed and its average value, ΔETavg, was used as a single feature to discriminate between ROSC and non-ROSC segments. RESULTS: A total of 384 segments (130 ROSC, 254 non-ROSC) from 205 OHCA patients (30.7% female, median age 66) were analyzed. Median (IQR) duration was 16.3 (12.9,18.1) s. ΔETavg was 0.0 (-0.7, 0.9)% for ROSC segments and -11.0 (-14.1, -8.0)% for non-ROSC segments (p < 0.0001). Best performance for ROSC detection yielded a sensitivity of 95.4% (95% CI: 90.1%, 98.1%) and a specificity of 94.9% (91.4%, 97.1%) for all ventilations in the segment. For the first 2 ventilations, duration was 7.7 (6.0, 10.2) s, and sensitivity and specificity were 90.0% (83.5%, 94.2%) and 89.4 (84.9%, 92.6%), respectively. Our method allowed for ROSC detection during the first compression pause in 95.4% of the patients. CONCLUSION: Average percent variation of ETCO2 during pauses in chest compressions allowed for ROSC discrimination. This metric could help confirm ROSC during compression pauses in ALS settings.


Assuntos
Dióxido de Carbono/metabolismo , Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/metabolismo , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Retrospectivos
10.
PLoS One ; 15(9): e0239950, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32997721

RESUMO

AIM: High-quality chest compressions is challenging for bystanders and first responders to out-of-hospital cardiac arrest (OHCA). Long compression pauses and compression rates higher than recommended are common and detrimental to survival. Our aim was to design a simple and low computational cost algorithm for feedback on compression rate using the transthoracic impedance (TI) acquired by automated external defibrillators (AEDs). METHODS: ECG and TI signals from AED recordings of 242 OHCA patients treated by basic life support (BLS) ambulances were retrospectively analyzed. Beginning and end of chest compression series and each individual compression were annotated. The algorithm computed a biased estimate of the autocorrelation of the TI signal in consecutive non-overlapping 2-s analysis windows to detect the presence of chest compressions and estimate compression rate. RESULTS: A total of 237 episodes were included in the study, with a median (IQR) duration of 10 (6-16) min. The algorithm performed with a global sensitivity in the detection of chest compressions of 98.7%, positive predictive value of 98.7%, specificity of 97.1%, and negative predictive value of 97.1% (validation subset including 207 episodes). The unsigned error in the estimation of compression rate was 1.7 (1.3-2.9) compressions per minute. CONCLUSION: Our algorithm is accurate and robust for real-time guidance on chest compression rate using AEDs. The algorithm is simple and easy to implement with minimal software modifications. Deployment of AEDs with this capability could potentially contribute to enhancing the quality of chest compressions in the first minutes from collapse.


Assuntos
Reanimação Cardiopulmonar/métodos , Desfibriladores , Parada Cardíaca Extra-Hospitalar/terapia , Algoritmos , Cardiografia de Impedância , Bases de Dados Factuais , Eletrocardiografia , Humanos , Monitorização Fisiológica/métodos , Parada Cardíaca Extra-Hospitalar/diagnóstico , Pressão , Estudos Retrospectivos , Sensibilidade e Especificidade
11.
PLoS One ; 15(2): e0228395, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023298

RESUMO

AIM: Current resuscitation guidelines recommend waveform capnography as an indirect indicator of perfusion during cardiopulmonary resuscitation (CPR). Chest compressions (CCs) and ventilations during CPR have opposing effects on the exhaled carbon dioxide (CO2) concentration, which need to be better characterized. The purpose of this study was to model the impact of ventilations in the exhaled CO2 measured from capnograms collected during out-of-hospital cardiac arrest (OHCA) resuscitation. METHODS: We retrospectively analyzed OHCA monitor-defibrillator files with concurrent capnogram, compression depth, transthoracic impedance and ECG signals. Segments with CC pauses, two or more ventilations, and with no pulse-generating rhythm were selected. Thus, only ventilations should have caused the decrease in CO2 concentration. The variation in the exhaled CO2 concentration with each ventilation was modeled with an exponential decay function using non-linear-least-squares curve fitting. RESULTS: Out of the original 1002 OHCA dataset (one per patient), 377 episodes had the required signals, and 196 segments from 96 patients met the inclusion criteria. Airway type was endotracheal tube in 64.8% of the segments, supraglottic King LT-D™ in 30.1%, and unknown in 5.1%. Median (IQR) decay factor of the exhaled CO2 concentration was 10.0% (7.8 - 12.9) with R2 = 0.98(0.95 - 0.99). Differences in decay factor with airway type were not statistically significant (p = 0.17). From these results, we propose a model for estimating the contribution of CCs to the end-tidal CO2 level between consecutive ventilations and for estimating the end-tidal CO2 variation as a function of ventilation rate. CONCLUSION: We have modeled the decrease in exhaled CO2 concentration with ventilations during chest compression pauses in CPR. This finding allowed us to hypothesize a mathematical model for explaining the effect of chest compressions on ETCO2 compensating for the influence of ventilation rate during CPR. However, further work is required to confirm the validity of this model during ongoing chest compressions.


Assuntos
Capnografia/métodos , Dióxido de Carbono/análise , Reanimação Cardiopulmonar/instrumentação , Modelos Teóricos , Monitorização Fisiológica , Parada Cardíaca Extra-Hospitalar/terapia , Ventilação/normas , Algoritmos , Cardiografia de Impedância , Reanimação Cardiopulmonar/normas , Expiração , Humanos , Taxa Respiratória , Estudos Retrospectivos
12.
Resuscitation ; 156: 215-222, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32622015

RESUMO

AIM: Ventilation rate is a confounding factor for interpretation of end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR). The aim of our study was to model the effect of ventilation rate on ETCO2 during manual CPR in adult out-of-hospital cardiac arrest (OHCA). METHODS: We conducted a retrospective analysis of OHCA monitor-defibrillator files with concurrent capnogram, compression depth, transthoracic impedance and ECG. We annotated pairs of capnogram segments presenting differences in average ventilation rate and average ETCO2 value but with other influencing factors (e.g. compression rate and depth) presenting similar values within the pair. ETCO2 variation as a function of ventilation rate was adjusted through curve fitting using non-linear least squares as a measure of goodness of fit. RESULTS: A total of 141 pairs of segments from 102 patients were annotated. Each pair provided a single data point for curve fitting. The best goodness of fit yielded a coefficient of determination R2 of 0.93. Our model described that ETCO2 decays exponentially with increasing ventilation rate. The model showed no differences attributable to the airway type (endotracheal tube or supraglottic King-LT-D). CONCLUSION: Capnogram interpretation during CPR is challenging since many factors influence ETCO2. For adequate interpretation, we need to know the effect of each factor on ETCO2. Our model allows quantifying the effect of ventilation rate on ETCO2 variation. Our findings could contribute to better interpretation of ETCO2 during CPR.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Adulto , Dióxido de Carbono , Humanos , Parada Cardíaca Extra-Hospitalar/terapia , Taxa Respiratória , Estudos Retrospectivos
13.
Resuscitation ; 153: 195-201, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32492455

RESUMO

BACKGROUND: Real-time measurement of end-tidal carbon dioxide (ETCO2) is used as a non-invasive estimate of cardiac output and perfusion during cardiopulmonary resuscitation (CPR). However, capnograms are often distorted by chest compressions (CCs) and this may affect ETCO2 measurement. The aim of the study was to quantify the effect of CC-artefact on the accuracy of ETCO2 measurements obtained during out-of-hospital manual CPR. METHODS: We retrospectively analysed monitor-defibrillator recordings collected by two advanced life support agencies during out-of-hospital cardiac arrest. These two agencies, represented as A and B used different side-stream capnometers and monitor-defibrillators. One-minute capnogram segments were reviewed. Each ventilation within each segment was identified using the transthoracic impedance signal and the capnogram. ETCO2 values per ventilation were manually annotated and compared to the corresponding capnometry values stored in the monitor-defibrillator. Ventilations were classified as distorted or non-distorted by CC-artefact. RESULTS: A total of 407 1-min capnogram segments from 65 patients were analysed. Overall, 4095 ventilations were annotated, 2170 (32.4% distorted) and 1925 (31.8% distorted) for agency A and B, respectively. Median (IQR) unsigned error in ETCO2 measurement increased from 1.5 (0.6-3.1)% for non-distorted to 5.5 (1.8-14.1)% for distorted ventilations; from 0.7 (0.3-1.2)% to 3.7 (1.0-9.9)% in agency A and from 2.3 (1.2-3.9)% to 8.3 (3.9-19.5)% in agency B (p < 0.001). Errors were higher than 10 mmHg in 9% and higher than 15 mmHg in 5% of the distorted ventilations. CONCLUSION: CC-artefact causes ETCO2 measurement errors in the two studied devices. This suggests that capnometer algorithms may need to be adapted to reliably perform in the presence of CC-artefact during CPR.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Capnografia , Dióxido de Carbono , Humanos , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Retrospectivos
14.
Resuscitation ; 142: 119-126, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31369793

RESUMO

AIM: Maximum velocity during chest recoil has been proposed as a metric for chest compression quality during cardiopulmonary resuscitation (CPR). This study investigated the relationship of the maximum velocities during compression and recoil phases with compression depth and rate in manual CPR. METHODS: We measured compression instances in out-of-hospital cardiac arrest recordings using custom Matlab programs. Each compression cycle was characterized by depth and rate, maximum compression and recoil velocities (CV and RV), and compression and recoil durations (total and effective). Mean compression and recoil velocities were computed as depth divided by compression and recoil durations, respectively. We correlated CV and RV with their corresponding mean velocities (total and effective), characterized by Pearson's correlation coefficient. RESULTS: CV/RV were strongly correlated with their corresponding mean velocities, with a median r of 0.83 (0.77-0.88)/0.82 (0.76-0.87) in per patient analysis, 0.86/0.88 for all the population. Correlation with mean effective velocities had a median r of 0.91 (0.87-0.94)/0.92 (0.89-0.94) in per-patient, 0.92/0.94 globally (p < 0.001). Total and effective compression and recoil durations were inversely proportional to compression rate. We observed similar RV values among compressions regardless of whether they were compliant with recommended depth and rate. Conversely, we observed different RV values among compressions having the same depth and rate, but presenting very distinct compression waveforms. CONCLUSION: CV and RV were highly correlated with compression depth and compression and recoil times, respectively. Better understanding of the relationship between novel and current quality metrics could help with the interpretation of CPR quality studies.


Assuntos
Reanimação Cardiopulmonar , Massagem Cardíaca , Parada Cardíaca Extra-Hospitalar/terapia , Fenômenos Biomecânicos/fisiologia , Reanimação Cardiopulmonar/métodos , Reanimação Cardiopulmonar/normas , Massagem Cardíaca/métodos , Massagem Cardíaca/normas , Humanos , Fatores de Tempo
15.
Resuscitation ; 76(2): 271-8, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17875356

RESUMO

AIM: To show the possibility of using cardiopulmonary resuscitation (CPR) artefact suppression methods that do not need additional reference signals to model CPR artefacts. MATERIALS AND METHODS: A CPR suppression method based on a Kalman filter was designed. The artefact was modelled using the fundamental frequency of the compressions, estimated from the spectral analysis of the ECG. Artificial mixtures of human shockable rhythms and CPR artefacts were used to design the algorithm that was then tested on samples obtained from real out-of-hospital cardiac arrest episodes. RESULTS: The shock/no-shock decision of an automated external defibrillator (AED) was evaluated before and after CPR suppression for 131 shockable and 347 non-shockable samples. The sensitivity improved from 56% (95% CI, 47-64%) to 90% (95% CI, 84-94%). However, the specificity decreased from 91% (95% CI, 87-93%) to 80% (95% CI, 76-84%). CONCLUSIONS: CPR artefacts can be suppressed using methods based on the analysis of the ECG alone. The hardware of current AEDs does not need to be replaced, although better artefact suppression methods exist for modified AEDs with additional reference channels.


Assuntos
Artefatos , Reanimação Cardiopulmonar/métodos , Eletrocardiografia/métodos , Parada Cardíaca/terapia , Algoritmos , Cardioversão Elétrica/instrumentação , Serviços Médicos de Emergência , Parada Cardíaca/fisiopatologia , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Resuscitation ; 130: 133-137, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29969643

RESUMO

BACKGROUND: Measurement of chest velocity has been proposed as an alternative method to identify responder leaning during cardiopulmonary resuscitation (CPR). Leaning is defined in terms of force, but no study has tested the utility of chest velocity in the presence of force measurements that directly measure leaning. MATERIALS AND METHODS: We analyzed 1004 out-of-hospital cardiac arrest (OHCA) files collected with Q-CPR monitors in the Portland, Oregon, USA metro region from 2006 to 2017. Records contained accelerometry and force signals. For each chest compression, the following metrics were computed: minimum force at the end of the compression (Frelease), compression depth, compression rate, maximum chest velocity during recoil (vrecoil) and maximum rate of change in force during chest release (ʋrelease). A compression was classified as having leaning if Frelease was greater than 2.5 kg-f. The ability of vrecoil and ʋrelease to predict Frelease was estimated with generalized linear models, and their ability to identify leaning with logistic regression. RESULTS: The data set contained over 1.5 million chest compressions, 21% compliant with 2015 rate and depth guidelines for CPR (the G2015 population). Leaning was uncommon generally (12%), and less common in G2015 compliant compressions (5%). Leaning and Frelease decreased with both vrecoil and ʋrelease but with extensive overlap. Neither vrecoil nor ʋrelease, alone or in combination with chest compression rate and depth, reliably predicted leaning or Frelease. CONCLUSION: Leaning cannot be reliably identified from vrecoil or ʋrelease, alone or in combination with currently recommended chest compression metrics in out-of-hospital CPR.


Assuntos
Acelerometria/métodos , Reanimação Cardiopulmonar , Massagem Cardíaca , Parada Cardíaca Extra-Hospitalar/terapia , Reanimação Cardiopulmonar/métodos , Reanimação Cardiopulmonar/estatística & dados numéricos , Feminino , Massagem Cardíaca/métodos , Massagem Cardíaca/normas , Humanos , Masculino , Pessoa de Meia-Idade , Melhoria de Qualidade , Reprodutibilidade dos Testes
17.
Resuscitation ; 133: 53-58, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30278204

RESUMO

BACKGROUND: Current resuscitation guidelines emphasize the use of waveform capnography to help guide rescuers during cardiopulmonary resuscitation (CPR). However, chest compressions often cause oscillations in the capnogram, impeding its reliable interpretation, either visual or automated. The aim of the study was to design an algorithm to enhance waveform capnography by suppressing the chest compression artefact. METHODS: Monitor-defibrillator recordings from 202 patients in out-of-hospital cardiac arrest were analysed. Capnograms were classified according to the morphology of the artefact. Ventilations were annotated using the transthoracic impedance signal acquired through defibrillation pads. The suppression algorithm is designed to operate in real-time, locating distorted intervals and restoring the envelope of the capnogram. We evaluated the improvement in automated ventilation detection, estimation of ventilation rate, and detection of excessive ventilation rates (over-ventilation) using the capnograms before and after artefact suppression. RESULTS: A total of 44 267 ventilations were annotated. After artefact suppression, sensitivity (Se) and positive predictive value (PPV) of the ventilation detector increased from 91.9/89.5% to 98.0/97.3% in the distorted episodes (83/202). Improvement was most noticeable for high-amplitude artefact, for which Se/PPV raised from 77.6/73.5% to 97.1/96.1%. Estimation of ventilation rate and detection of over-ventilation also upgraded. The suppression algorithm had minimal impact in non-distorted data. CONCLUSION: Ventilation detection based on waveform capnography improved after chest compression artefact suppression. Moreover, the algorithm enhances the capnogram tracing, potentially improving its clinical interpretation during CPR. Prospective research in clinical settings is needed to understand the feasibility and utility of the method.


Assuntos
Suporte Vital Cardíaco Avançado/métodos , Artefatos , Capnografia/estatística & dados numéricos , Massagem Cardíaca/efeitos adversos , Algoritmos , Desfibriladores/efeitos adversos , Humanos , Parada Cardíaca Extra-Hospitalar/terapia , Avaliação de Resultados em Cuidados de Saúde , Sistema de Registros , Taxa Respiratória , Estudos Retrospectivos
18.
Resuscitation ; 124: 63-68, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29246741

RESUMO

BACKGROUND: Capnography has been proposed as a method for monitoring the ventilation rate during cardiopulmonary resuscitation (CPR). A high incidence (above 70%) of capnograms distorted by chest compression induced oscillations has been previously reported in out-of-hospital (OOH) CPR. The aim of the study was to better characterize the chest compression artefact and to evaluate its influence on the performance of a capnogram-based ventilation detector during OOH CPR. METHODS: Data from the MRx monitor-defibrillator were extracted from OOH cardiac arrest episodes. For each episode, presence of chest compression artefact was annotated in the capnogram. Concurrent compression depth and transthoracic impedance signals were used to identify chest compressions and to annotate ventilations, respectively. We designed a capnogram-based ventilation detection algorithm and tested its performance with clean and distorted episodes. RESULTS: Data were collected from 232 episodes comprising 52 654 ventilations, with a mean (±SD) of 227 (±118) per episode. Overall, 42% of the capnograms were distorted. Presence of chest compression artefact degraded algorithm performance in terms of ventilation detection, estimation of ventilation rate, and the ability to detect hyperventilation. CONCLUSION: Capnogram-based ventilation detection during CPR using our algorithm was compromised by the presence of chest compression artefact. In particular, artefact spanning from the plateau to the baseline strongly degraded ventilation detection, and caused a high number of false hyperventilation alarms. Further research is needed to reduce the impact of chest compression artefact on capnographic ventilation monitoring.


Assuntos
Artefatos , Capnografia/métodos , Massagem Cardíaca/efeitos adversos , Respiração , Algoritmos , Capnografia/estatística & dados numéricos , Reanimação Cardiopulmonar/métodos , Desfibriladores , Cardioversão Elétrica/estatística & dados numéricos , Humanos , Sensibilidade e Especificidade
19.
Technol Health Care ; 26(3): 529-535, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29710761

RESUMO

BACKGROUND: Out-of-hospital cardiac arrest is common in public locations, including public transportation sites. Feedback devices are increasingly being used to improve chest-compression quality. However, their performance during public transportation has not been studied yet. OBJECTIVE: To test two CPR feedback devices representative of the current technologies (accelerometer and electromag- netic-field) in a long-distance train. METHODS: Volunteers applied compressions on a manikin during the train route using both feedback devices. Depth and rate measurements computed by the devices were compared to the gold-standard values. RESULTS: Sixty-four 4-min records were acquired. The accelerometer-based device provided visual help in all experiments. Median absolute errors in depth and rate were 2.4 mm and 1.3 compressions per minute (cpm) during conventional speed, and 2.5 mm and 1.2 cpm during high speed. The electromagnetic-field-based device never provided CPR feedback; alert messages were shown instead. However, measurements were stored in its internal memory. Absolute errors for depth and rate were 2.6 mm and 0.7 cpm during conventional speed, and 2.6 mm and 0.7 cpm during high speed. CONCLUSIONS: Both devices were accurate despite the accelerations and the electromagnetic interferences induced by the train. However, the electromagnetic-field-based device would require modifications to avoid excessive alerts impeding feedback.


Assuntos
Reanimação Cardiopulmonar/métodos , Feedback Formativo , Manequins , Parada Cardíaca Extra-Hospitalar/terapia , Ferrovias , Aceleração , Campos Eletromagnéticos , Humanos
20.
Resuscitation ; 128: 158-163, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29733921

RESUMO

AIM: To design and evaluate a simple algorithm able to discriminate pulsatile rhythms from pulseless electrical activity during automated external defibrillator (AED) analysis intervals, using the ECG and the transthoracic impedance (TI) acquired from defibrillation pads. METHODS: ECG and TI signals from out-of-hospital AED recordings were retrospectively analysed. Experts annotated the cardiac rhythm during AED analysis intervals and at the end of each episode. We developed an algorithm to classify 3-s segments of non-shockable and non-asystole rhythms as either pulsatile rhythm or pulseless electrical activity. The algorithm consisted on a decision tree based on two features: the mean power of the TI segment and the mean cross-power between ECG and TI segments. RESULTS: From the 302 annotated episodes, 167 contained segments eligible for the study. The circulation detector algorithm presented a sensitivity (ability of detecting pulsatile rhythms) of 98.3% (95% CI: 95.1-100) and a specificity (ability to detect pulseless electrical activity) of 98.4% (95% CI: 97.1-99.8) in the validation subset. Absence of pulsatile rhythm was confirmed during the first AED analysis interval in 98.9% of the episodes, and presence of a pulse was confirmed in the first 3 s of all intervals with annotated return of spontaneous circulation. CONCLUSION: Accurate automated detection of circulation based on TI and ECG is possible during AED analysis intervals. This functionality could potentially contribute to enhance patient's care by laypersons using AEDs.


Assuntos
Cardiografia de Impedância , Desfibriladores/estatística & dados numéricos , Eletrocardiografia/estatística & dados numéricos , Parada Cardíaca Extra-Hospitalar/diagnóstico , Fluxo Pulsátil , Circulação Sanguínea , Reanimação Cardiopulmonar/métodos , Feminino , Humanos , Masculino , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Retrospectivos
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