The POCUS Pulse Check: A Case Series on a Novel Method for Determining the Presence of a Pulse Using Point-of-Care Ultrasound

Artificial intelligence-based evaluation of carotid artery compressibility via point-of-care ultrasound in determining the return of spontaneous circulation during cardiopulmonary resuscitation

AIM

This study introduces RealCAC-Net, an artificial intelligence (AI) system, to quantify carotid artery compressibility (CAC) and determine the return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation.

METHODS

A prospective study based on data from a South Korean emergency department from 2022 to 2023 investigated carotid artery compressibility in adult patients with cardiac arrest using a novel AI model, RealCAC-Net. The data comprised 11,958 training images from 161 cases and 15,080 test images from 134 cases. RealCAC-Net processes images in three steps: TransUNet-based segmentation, the carotid artery compressibility measurement algorithm for improved segmentation and CAC calculation, and CAC-based classification from 0 (indicating a circular shape) to 1 (indicating high compression). The accuracy of the ROSC classification model was tested using metrics such as the dice similarity coefficient, intersection-over-union, precision, recall, and F1 score.

RESULTS

RealCAC-Net, which applied the carotid artery compressibility measurement algorithm, performed better than the baseline model in cross-validation, with an average dice similarity coefficient of 0.90, an intersection-over-union of 0.84, and a classification accuracy of 0.96. The test set achieved a classification accuracy of 0.96 and an F1 score of 0.97, demonstrating its efficacy in accurately identifying ROSC in cardiac arrest situations.

CONCLUSIONS

RealCAC-Net enabled precise CAC quantification for ROSC determination during cardiopulmonary resuscitation. Future research should integrate this AI-enhanced ultrasound approach to revolutionize emergency care.

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 RescueDoppleŕs 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.

The Feasibility of Using Point-of-Care Ultrasound During Cardiac Arrest in Children: Rapid Apical Contractility Evaluation

INTRODUCTION

Resuscitation guidelines emphasize minimal interruption of compressions during cardiopulmonary resuscitation. Point-of-care ultrasound (POCUS) enables the clinician to visualize cardiac contractility and central artery pulsatility. The apical 4-chamber (A4), subxiphoid (SX), and femoral artery views may be used when defibrillator pads or active compressions preclude parasternal cardiac views. We hypothesized that clinicians can rapidly obtain interpretable POCUS views in healthy children from the A4, SX, and femoral positions.

METHODS

A prospective study of pediatric emergency medicine providers in an urban academic hospital was performed. Stable patients of 12 years or younger were scanned. Sonologists were each allotted 10 seconds to acquire A4, SX, and femoral views. Two attempts at each view were allowed. The primary outcome was whether cardiac and femoral artery scans were interpretable for contractility and pulsatility, respectively. The secondary outcome was whether cardiac scans were interpretable for effusion or right ventricular strain. A POCUS expert reviewed scans to confirm interpretability.

RESULTS

Twenty-two sonologists performed a total of 50 scans on 22 patients. A view that was interpretable for contractility was obtained on the first attempt in 86% of A4 and 94% of SX scans. A femoral view that was interpretable for pulsatility was obtained on the first attempt in 74% of scans. Expert review was concordant with sonologist interpretation.

CONCLUSIONS

Pediatric emergency medicine physicians can obtain interpretable cardiac and central artery views within 10 seconds most of the time. Point-of-care ultrasound has the potential to enhance care during pediatric resuscitation. Future studies on the impact of POCUS pulse checks in actual pediatric resuscitations should be performed.

Diagnostic test accuracy for cessation of circulation during death determination: a systematic review

PURPOSE

To synthesize the available evidence comparing noninvasive methods of measuring the cessation of circulation in patients who are potential organ donors undergoing death determination by circulatory criteria (DCC) with the current accepted standard of invasive arterial blood pressure (IAP) monitoring.

SOURCE

We searched (from inception until 27 April 2021) MEDLINE, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials. We screened citations and manuscripts independently and in duplicate for eligible studies that compared noninvasive methodologies assessing circulation in patients who were monitored around a period of cessation of circulation. We performed risk of bias assessment, data abstraction, and quality assessment using Grading of Recommendations, Assessment, Development, and Evaluation in duplicate and independently. We presented findings narratively.

PRINCIPAL FINDINGS

We included 21 eligible studies (N = 1,177 patients). Meta-analysis was not possible because of study heterogeneity. We identified low quality evidence from four indirect studies (n = 89) showing pulse palpation is less sensitive and specific than IAP (reported sensitivity range, 0.76-0.90; specificity, 0.41-0.79). Isoelectric electrocardiogram (ECG) had excellent specificity for death (two studies; 0% [0/510]), but likely increases the average time to death determination (moderate quality evidence). We are uncertain whether point-of-care ultrasound (POCUS) pulse check, cerebral near-infrared spectroscopy (NIRS), or POCUS cardiac motion assessment are accurate tests for the determination of circulatory cessation (very low-quality evidence).

CONCLUSION

There is insufficient evidence that ECG, POCUS pulse check, cerebral NIRS, or POCUS cardiac motion assessment are superior or equivalent to IAP for DCC in the setting of organ donation. Isoelectric ECG is specific but can increase the time needed to determine death. Point-of-care ultrasound techniques are emerging therapies with promising initial data but are limited by indirectness and imprecision.

STUDY REGISTRATION

PROSPERO (CRD42021258936); first submitted 16 June 2021.

Point-of-Care Ultrasound for Pulse Checks in Pediatric Cardiac Arrest: Two Illustrative Cases

ABSTRACT

Cardiac arrest is an infrequent but high-stakes scenario in pediatrics. Manual central pulse checks are unreliable. Point-of-care ultrasound is a noninvasive technique to visualize the heart and central vessels during resuscitation. We describe 2 cases in which point-of-care ultrasound helped aid management decisions in pediatric cardiac arrest.

Point-of-Care Ultrasound Compression of the Carotid Artery for Pulse Determination in Cardiopulmonary Resuscitation

AIM

To identify whether a novel pulse check technique, carotid artery compression using an ultrasound probe, can reduce pulse check times compared to manual palpation (MP).

METHODS

This prospective study was conducted in an emergency department between February and December 2021. A physician applied point-of-care ultrasound-carotid artery compression (POCUS-CAC) and assessed the carotid artery compressibility and pulsatility by probe compression during rhythm check time. Another clinician performed MP of the femoral artery. The primary outcome was the difference in the average time for pulse assessment between POCUS-CAC and MP. The secondary outcomes included the time difference in each pulse check between methods, the proportion of times greater than 5 s and 10 s, and the prediction of return of spontaneous circulation (ROSC) during ongoing chest compression.

RESULTS

25 cardiac arrest patients and 155 pulse checks were analyzed. The median (interquartile range) average time to carotid pulse identification per patient using POCUS-CAC was 1.62 (1.14-2.14) s compared to 3.50 (2.99-4.99) s with MP. In all 155 pulse checks, the POCUS-CAC time to determine ROSC was significantly shortened to 0.44 times the MP time (P < 0.001). The POCUS-CAC approach never exceeded 10 s, and the number of patients who required more than 5 s was significantly lower (5 vs. 37, P < 0.001). Under continuous chest compression, six pulse checks predicted the ROSC.

CONCLUSIONS

We found that emergency physicians could quickly determine pulses by applying simple POCUS compression of the carotid artery in cardiac arrest patients.

Initiation of Invasive Arterial Pressure Monitoring by Critical Care Transport Crews

Noninvasive blood pressure monitoring is convenient in the prehospital setting, but its use in the critically ill patient should be carefully considered given documented inaccuracies. Countless therapeutic patient interventions are based on blood pressure parameters, and the prehospital paramedic, nurse, and physician should strongly consider the use of invasive blood pressure monitoring, especially during critical care transport. Radial artery cannulation for arterial blood pressure monitoring is a safe and effective procedure that can reasonably be performed in the prehospital setting by both physicians and nonphysicians. Critical care transport teams should consider clinical guidelines that outline indications and training to safely implement this as a clinical skill.

Point-of-Care Ultrasound Use by EMS Providers in Out-of-Hospital Cardiac Arrest

AIM

Paramedics received training in point-of-care ultrasound (POCUS) to assess for cardiac contractility during management of medical out-of-hospital cardiac arrest (OHCA). The primary outcome was the percentage of adequate POCUS video acquisition and accurate video interpretation during OHCA resuscitations. Secondary outcomes included POCUS impact on patient management and resuscitation protocol adherence.

METHODS

A prospective, observational cohort study of paramedics was performed following a four-hour training session, which included a didactic lecture and hands-on POCUS instruction. The Prehospital Echocardiogram in Cardiac Arrest (PECA) protocol was developed and integrated into the resuscitation algorithm for medical non-shockable OHCA. The ultrasound (US) images were reviewed by a single POCUS expert investigator to determine the adequacy of the POCUS video acquisition and accuracy of the video interpretation. Change in patient management and resuscitation protocol adherence data, including end-tidal carbon dioxide (EtCO2) monitoring following advanced airway placement, adrenaline administration, and compression pauses under ten seconds, were queried from the prehospital electronic health record (EHR).

RESULTS

Captured images were deemed adequate in 42/49 (85.7%) scans and paramedic interpretation of sonography was accurate in 43/49 (87.7%) scans. The POCUS results altered patient management in 14/49 (28.6%) cases. Paramedics adhered to EtCO2 monitoring in 36/36 (100.0%) patients with an advanced airway, adrenaline administration for 38/38 (100.0%) patients, and compression pauses under ten seconds for 36/38 (94.7%) patients.

CONCLUSION

Paramedics were able to accurately obtain and interpret cardiac POCUS videos during medical OHCA while adhering to a resuscitation protocol. These findings suggest that POCUS can be effectively integrated into paramedic protocols for medical OHCA.

Manual Palpation vs. Femoral Arterial Doppler Ultrasound for Comparison of Pulse Check Time During Cardiopulmonary Resuscitation in the Emergency Department: A Pilot Study

BACKGROUND

Manual palpation (MP) is frequently employed for pulse checks, but studies have shown that trained medical personnel have difficulty accurately identifying pulselessness or return of spontaneous circulation (ROSC) using MP. Any delays in identifying pulselessness can lead to significant delays in starting or resuming high-quality chest compressions.

OBJECTIVES

This study explored whether femoral arterial Doppler ultrasound (FADU) decreases pulse check duration during cardiopulmonary resuscitation (CPR) compared with MP among patients in the emergency department (ED) receiving CPR directed by emergency medicine physicians who had received minimal additional didactic ultrasound training.

METHODS

We performed a prospective observational cohort study from October 2018 to May 2019 at an urban community ED. Using convenience sampling, we enrolled patients arriving at our ED or who decompensated during their ED stay and received CPR. For continuous data, median (interquartile range [IQR]) were calculated, and medians were compared using Kruskal-Wallis test.

RESULTS

Fifty-two eligible patients were enrolled and 135 pulse checks via MP and 35 via FADU were recorded. MP observations had a median (IQR) of 11.00 (7.36-15.48) s, whereas FADU had a median (IQR) of 8.98 (5.45-13.85) s. There was a difference between the two medians of 2.02 s (p = 0.05).

CONCLUSIONS

In this study, the use of FADU was superior to MP in achieving shorter pulse check times. Further research is needed to confirm the accuracy of FADU for identifying ROSC as well as to determine whether FADU can improve clinical outcomes.

Checking the pulse in the 21st century: Interobserver reliability of carotid pulse detection by point-of-care ultrasound

INTRODUCTION

Detection of a pulse is crucial to decision-making in the care of patients who are in cardiac arrest, however, the current standard of manual pulse palpation is unreliable. An emerging alternative is the use of point-of-care ultrasound (POCUS) for direct assessment of the carotid pulse. The primary objective of this study is to determine the interobserver reliability for physician interpretation of pre-recorded point-of-care ultrasound pulse-check clips for patients who are in cardiac arrest.

METHODS

We conducted a web-based survey of residents and physicians working in an academic center. Participants were shown a tutorial demonstrating POCUS detection of the carotid pulse and then asked to interpret 15 carotid pulse ultrasound clips from patients who were in cardiac arrest. The primary outcome was interobserver reliability for carotid pulse assessment. Secondary outcomes included interobserver reliability stratified by physician role and POCUS experience, median tutorial and median pulse assessment duration. Interobserver reliability was determined by Krippendorff's ⍺.

RESULTS

68 participants completed the study, with a response rate of 75%. There was high interobserver reliability for pulse assessment amongst all study participants (⍺ = 0.874, 95% CI 0.869 to 0.879). All sub-groups had ⍺ greater than 0.8. Median tutorial duration was 35 s (IQR 29). Median pulse assessment duration was 6 s (IQR 5) with 76% of assessments completed within 10 s.

CONCLUSION

Interpretation of the carotid pulse by POCUS showed high interobserver reliability. Further work must be done to determine the performance of POCUS pulse assessment in real-time for patients who are in cardiac arrest.

Assessing the validity of two-dimensional carotid ultrasound to detect the presence and absence of a pulse

BACKGROUND

Traditional assessment of return of cardiac output in cardiac arrest by manual palpation has poor accuracy. Point of care ultrasound of a major artery has been suggested as an alternative. We conducted a diagnostic accuracy study of two-dimensional carotid ultrasound to detect the presence or absence of a pulse, using cardiopulmonary bypass patients for pulse and pulseless states.

METHODS

A cross-sectional multi-patient, multi-reader repeated measures diagnostic study was conducted. For patients undergoing routine cardiopulmonary bypass, a portable ultrasound was used to record four 10-s videos the common carotid artery, three aimed for a pulse in high (>90 mmHg), medium (70-90 mmHg) and low (<70 mmHg) systolic blood pressure (SBP) ranges, and a pulseless video was recorded on cardiopulmonary bypass. Critical care physicians viewed the videos and were asked to nominate within 10 s if a pulse was present. True pulse-status was determined via the arterial-line waveform.

RESULTS

Twenty-three patients had all four videos collected. Median patient age was 64 (IQR 14), sixteen were male (70%) and median BMI was 27. The median SBP in high-, medium- and low-SBP groups were 120 mmHg, 83 mmHg and 69 mmHg respectively. Forty-six physicians reviewed a subset of 24 videos. Overall sensitivity was 0.91 (95% confidence interval 0.89-0.93) and specificity 0.90 (95% CI 0.86-0.93). Sensitivity was highest in the high-SBP group (0.96, 95% CI 0.93-0.98) and lowest in the low-SBP group (0.83, 95% CI 0.78-0.87).

CONCLUSION

2D ultrasound of the common carotid artery is both sensitive and specific for detection of the presence or absence of a pulse.