Diagnostic Accuracy of Point-of-Care Ultrasound for Patients With Cardiogenic Shock　― A Meta-Analysis and Systematic Review ―

Abstract

Background

Cardiogenic shock, cardiac tamponade, and pulmonary embolism are critical conditions in cardiovascular emergencies, characterized by high mortality rates. Early diagnosis and treatment are essential to improve outcomes. Point-of-care ultrasound (POCUS) has emerged as a noninvasive tool for evaluating shock. However, further assessment through the latest meta-analyses is necessary to comprehensively evaluate its diagnostic accuracy in cardiogenic emergencies. Therefore, in this study, we conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of POCUS in patients with cardiogenic and obstructive shock.

Methods and Results

Up to December 31, 2023, we systematically reviewed 9 studies reporting all 4 values (true positive, false positive, false negative, and true negative) published in the PubMed, Web of Science, and CENTRAL databases: 8 studies assessed cardiac shock, and 8 assessed obstructive shock separately. For cardiac shock, the pooled sensitivity was 86.1% (95% confidence interval [CI]: 71.5–93.9%), and specificity was 95.8% (95% CI: 94.0–97.2%). For obstructive shock, the pooled sensitivity was 77.5% (95% CI: 62.5–87.6%) and specificity was 97.6% (95% CI: 93.9–99.1%). The area under the curve was 0.96 (95% CI: 0.95–0.98) for cardiogenic shock and 0.94 (95% CI: 0.88–0.98) for obstructive shock.

Conclusions

This meta-analysis suggested that POCUS has reasonable diagnostic accuracy for cardiogenic and obstructive shock, particularly with high pooled specificity.

Cardiogenic emergencies, including cardiac shock, cardiac tamponade, and pulmonary embolism, are common life-threatening conditions in emergency departments and often lead to poor outcomes.^1,2 Early diagnosis and prompt management of cardiogenic shock are essential to improve patient survival.^3–5 However, patients with cardiogenic shock frequently present with subtle signs and symptoms, and impaired consciousness complicates history-taking and thus the diagnosis. Delayed diagnosis may result in postponed initiation of specific treatments such as inotropes and mechanical circulatory support. These factors highlight the need for a simple, accurate, and objective diagnostic tool to enable early diagnosis of cardiogenic shock.

Point-of-care ultrasound (POCUS) has become an essential bedside tool in emergency medicine, as it is recommended for initial evaluation of shock and assessment of underlying pathophysiology.⁶ As a noninvasive, reliable, and repeatable modality, POCUS provides significant advantages for evaluating critically ill patients in emergency departments. Several studies have demonstrated its diagnostic accuracy for cardiogenic shock,^7–10 with systematic reviews and meta-analyses further validating its utility.^11,12

Recent advances in cardiogenic shock management have reshaped clinical practice, and although studies evaluating POCUS diagnostic accuracy are steadily increasing,^13–18 current meta-analyses evaluating POCUS diagnostic accuracy for cardiogenic shock remain limited.

To address this gap, we aimed to evaluate the diagnostic accuracy of POCUS in patients with cardiogenic and obstructive shock during cardiogenic emergencies, providing clinical evidence for POCUS utilization.

Methods

The Japan Resuscitation Council (JRC) Emergency Cardiovascular Care Cardiovascular Shock Task Force was established through the collaboration of the Japanese Circulation Society, and the Japanese Society of Internal Medicine. This Task Force was created specifically to inform the 2025 JRC guidelines and established 12 clinically relevant questions. In this study, we address 1 key clinical question: Does POCUS improve diagnostic accuracy in patients with suspected cardiogenic shock?

PICOT Criteria

P (Population): Adult patients (≥18 years) presenting to emergency departments with undifferentiated shock (including cardiogenic shock, cardiac tamponade, and pulmonary embolism)

I (Index test): POCUS examination

C (Comparator): Final diagnosis established by physicians using comprehensive clinical data (including medical records, imaging studies, and expert consensus review)

O (Outcome): Diagnostic sensitivity and specificity

T (Target condition): Cardiogenic or obstructive shock

Our meta-analysis and systematic review were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.¹⁹ Ethical approval was waived for this study as it involved analysis of previously published data.

Search Strategy and Data Extraction

We included English-language studies meeting all the PICOT criteria regardless of study design. Our comprehensive literature search encompassed the PubMed, Web of Science, and CENTRAL databases for publications related to cardiogenic/obstructive shock and POCUS from inception through to December 31, 2023. We focused on POCUS performed during initial emergency department evaluation. POCUS was operationally defined as bedside cardiac ultrasound using echocardiography to determine shock etiology during initial evaluation. Cardiogenic shock was defined as tissue hypoperfusion resulting from primary cardiac dysfunction, typically caused by conditions such as acute heart failure, myocardial infarction, valvular disease, myocarditis, or severe arrhythmias. Our search strategy used the following key terms: shock, hypotension, ultrasound, echocardiography, point-of-care ultrasound, and POCUS (Supplementary Table). We classified shock from cardiac tamponade and pulmonary embolism as obstructive shock, conducting separate analyses for this category. Two investigators (T.O., N.N.) independently screened all the identified records (titles/abstracts) and evaluated full-text articles. Discrepancies were resolved through consensus discussion. The exclusion criteria included duplicate publications, studies lacking extractable data, review articles, case reports/case series, letters/commentaries, animal studies, and non-English publications.

Risk of Bias Assessment

The same 2 authors independently evaluated the methodological quality of included studies using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool,²⁰ which assesses 4 domains: patient selection, index test, reference standard, and flow and timing. Each domain was rated in 2 categories: risk of bias and applicability concerns. Ratings were classified as “low”, “high” or “unclear” risk. We did not assess publication or reporting bias because no established method exists for diagnostic accuracy meta-analyses. These results are shown in the Central Figure.

Rating the Certainty of Evidence

The GRADEpro system was used to evaluate the quality of evidence for diagnostic studies, assessing 5 key factors: risk of bias, indirectness, inconsistency, imprecision, and publication bias. The certainty of the evidence was categorized as high, moderate, low, or very low.^21,22

Statistical Analysis

We conducted all statistical analyses using Review Manager version 5.4 (The Nordic Cochrane Center, The Cochrane Collaboration, Copenhagen, Denmark) and R version 4.4.2 (The R Foundation for Statistical Computing, Vienna, Austria). The estimated absolute numbers of test positives (true positives + false positives) and test negatives (true negatives + false negatives) per 1,000 patients were determined by applying pooled sensitivity and specificity values together with pretest probabilities. We assessed the generated summary receiver operating characteristic (SROC) curves for cardiogenic and obstructive shock using hierarchical bivariate meta-analysis (Reitsma’s model). The bootstrap approach was used to estimate the 95% confidence intervals (CIs) for the area under the curve (AUC) of SROC curves; we also evaluated their inconsistencies (I²).

Results

Search Results and Characteristics of the Included Studies

Figure 1 presents the study selection flow diagram. Our systematic search identified 3,759 records across the PubMed, Web of Science, and CENTRAL databases. Following title/abstract screening, 28 articles were included for full-text review; 9 studies ultimately met the inclusion criteria for meta-analysis, including 8 studies^{7–10,23–26} evaluating cardiogenic shock and 8 studies^{7,9,10,23–27} assessing obstructive shock.

Figure 1.

Study flowchart. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Study Characteristics

Table 1 summarizes the characteristics of the studies evaluating POCUS for cardiogenic and obstructive shock. Our analysis included 783 patients with undifferentiated shock, assessed for cardiogenic shock, and 863 patients with undifferentiated shock, evaluated for obstructive shock. The studies comprised 1 randomized-controlled trial (RCT) and 8 observational studies. The prevalence of cardiogenic shock ranged from 8.6% to 29.0%, while the prevalence of obstructive shock ranged from 2.9% to 41.0%. Shock definitions varied across studies, and all POCUS exams were conducted in the emergency department, with emergency physicians performing POCUS in all but 1 study.

Table 1.

Baseline Clinical Characteristics of Included Studies

Study	Study type	Sample size	No. of patients		Setting	Definition of shock	POCUS performers	Reference standard
			Cardiogenic shock	Obstructive shock
Geng P et al. (2022)24	Observational study	112	19	5	Emergency department	SBP <90 mmHg, or SI >1.0	Emergency physicians	Final diagnosis by a panel of 3 board- certified physicians from the comprehensive clinical data
Ienghong K et al. (2022)25	Observational study	102	15	4	Emergency department	SBP <90 mmHg, mean BP <65 mmHg, or 40 mmHg reduction from baseline	POCUS-trained emergency medical residents	Final diagnosis from the medical records
Javali RH et al. (2020)10	Observational study	100	19	4	Emergency department	SBP <90 mmHg, or SI >1.0 with symptoms	POCUS-trained emergency physicians	Final diagnosis by the treating physician in charge
Ghane MR et al. (2015)7	Observational study	69	20	11	Emergency department	SBP <100 mmHg, or SI >1.0	Emergency physicians, or radiologists	Final diagnosis by the treating physician in charge
Peach M et al. (2023)23	RCT	138	16	5	Emergency department	SBP <100 mmHg, or SI >1.0	POCUS-certified emergency physicians or supervised residents	Definitive diagnosis by independent chart review by 2 blinded emergency clinicians after 30 days or postmortem
Nazerian P et al. (2018)27	Observational study	105	NA	43	Emergency department	SBP <90 mmHg, or 40 mmHg reduction from baseline with symptoms	Sonographer	Final diagnosis from computed tomography, or pulmonary angiography
Rahulkumar HH et al. (2019)9	Observational study	97	27	15	Emergency department	SBP <90 mmHg, or SI >1.0	Emergency physicians	Diagnosis of shock by departmental consultants based on clinical history, physical examination, and detailed laboratory and radiological investigations
Ramadan A et al. (2022)26	Observational study	140	12	4	Emergency department	SBP <100 mmHg, or SI >1.0 with symptoms	Emergency physicians	Final diagnosis by external staff not involving the study
Bagheri-Hariri S et al. (2015)8	Observational study	25	3	NA	Emergency department	SBP <90 mmHg, or SI >1.0 with symptoms	Emergency physicians with departmental ultrasound credentials	Final diagnosis from all the medical information

NA, not available; POCUS, point-of-care ultrasound; RCT, randomized-controlled study; SBP, systolic blood pressure; SI, shock index.

Figure 2 presents the forest plot of POCUS diagnostic accuracy across the included studies. The sensitivity varied for both shock types; however, the specificity of each study was consistently high.

Figure 2.

Forest plots of diagnostic accuracy of point-of-care ultrasound (POCUS) in the included studies for (A) cardiogenic shock and (B) obstructive shock. CI, confidence interval; FN, false negative; FP, false positive; TN, true negative; TP, true positive.

Assessment of Risk of Bias

Figure 3 presents the QUADAS-2 quality assessment results for the included studies. The evaluation revealed a generally low risk of bias and applicability concerns across most domains, high risk of bias in patient selection for 3 studies, applicability concerns in the index test domain for 3 studies, and overall reliable methodological quality in most domains.

Figure 3.

Risk of bias assessment for the included studies.

Table 2 summarizes the clinical question findings and evidence quality assessment using the GRADEpro system. Concerning factors limiting the reliability of the evidence included:

Table 2.

Summary of Findings of the Analysis, Cardiogenic Shock (A) and Obstructive Shock (B)

(A) Outcome	No. of studies (no. of patients)	Study design	Factors that may decrease certainty of evidence					Effect per 1,000 patients tested			Test accuracy CoE
			Risk of bias	Indirectness	Inconsistency	Imprecision	Publication bias	Pretest probability of 30%*	Pretest probability of 15%*	Pretest probability of 10%*
True positives	8 studies (783 patients)	7 observational studies/ 1 RCT	Seriousa	Not serious	Seriousb	Not serious	Not serious	260 (216–282)	130 (108–141)	87 (72–94)	⊕⊕○○ Low
False negatives								40 (18–84)	20 (9–42)	13 (6–28)
True negatives	8 studies (783 patients)	7 observational studies/ 1 RCT	Seriousc	Not serious	Not serious	Not serious	Not serious	659 (615–681)	801 (747–827)	848 (791–876)	⊕⊕⊕○ Moderate
False positives								41 (19–85)	49 (23–103)	52 (24–109)
(B) Outcome	No. of studies (no. of patients)	Study design	Factors that may decrease certainty of evidence					Effect per 1,000 patients tested			Test accuracy CoE
			Risk of bias	Indirectness	Inconsistency	Imprecision	Publication bias	Pretest probability of 40%*	Pretest probability of 20%*	Pretest probability of 5%*
True positives	8 studies (863 patients)	7 observational studies/ 1 RCT	Seriousd	Not serious	Seriouse	Not serious	Not serious	329 (259–369)	165 (129–184)	41 (32–46)	⊕⊕○○ Low
False negatives								71 (31–141)	35 (16–71)	9 (4–18)
True negatives	8 studies (863 patients)	7 observational studies/ 1 RCT	Seriousf	Not serious	Not serious	Not serious	Not serious	580 (542–593)	774 (722–791)	919 (858–940)	⊕⊕⊕○ Moderate
False positives								20 (7–58)	26 (9–78)	31 (10–92)

^a,c,d,fRisk of bias: rated “serious” for both sensitivity and specificity, owing to non-consecutive case selection in some studies, and variability in POCUS operators across studies. ^b,eInconsistency: rated “serious” because of significant variation in sensitivity estimates for both shock types. CoE, certainty of evidence; RCT, randomized-controlled study.

• Risk of bias: rated “serious” for both sensitivity and specificity due to non-consecutive case selection in some studies, and variability in POCUS operators across studies.

• Inconsistency: Rated “serious” due to significant variation in sensitivity estimates for both shock types.

Therefore, the certainty of the evidence on sensitivity and specificity of POCUS was low and moderate, respectively.

Results of Syntheses for Diagnostic Accuracy of POCUS

Figure 4 presents the SROC for diagnostic accuracy of POCUS for shock evaluation. In the diagnosis of POCUS for cardiogenic shock, the pooled sensitivity and specificity were 86.1% (95% CI: 71.5–93.9%) and 95.8% (95% CI: 94.0–97.2%), respectively. In POCUS for obstructive shock, the pooled sensitivity and specificity were 77.5% (95% CI: 62.5–87.6%) and 97.6% (95% CI: 93.9–99.1%), respectively. The AUC for cardiogenic and obstructive shock was 0.96 (95% CI: 0.95–0.98) and 0.94 (95% CI: 0.88–0.99), respectively. The I² value of cardiogenic shock and obstructive shock was 0%.

Figure 4.

Summary receiver operating characteristic (SROC) plots demonstrate the overall diagnostic performance of the studies evaluating the accuracy of POCUS for (A) cardiogenic shock and (B) obstructive shock using the hierarchical bivariate meta-analysis. The solid black curve shows the fitted SROC curve derived from the Reitsma’s model. The filled black circle illustrates the summary point, representing the pooled sensitivity and specificity from included studies. The circles correspond to individual study with their size proportional to the study samples.

Table 2 demonstrates the estimated absolute numbers of true positives, false positives, true negatives, and false negatives expected per 1,000 people tested. These numbers were derived based on the pooled sensitivity and specificity. The estimated pretest probabilities of the population in cardiogenic shock were set at 30%, 15%, and 10%, considering cardiogenic shock prevalence ranging from 8.6% to 29.0%. The estimated false positives was 52 per 1,000 (95% CI: 24–109 per 1,000), with an assumed baseline risk of 10%. The estimated number of false negatives was 40 per 1,000 (95% CI: 18–84 per 1,000), with an assumed baseline risk of 30%. Conversely, the estimated pretest probabilities of the population in obstructive shock were set at 40%, 20%, and 5%, given the prevalence of obstructive shock ranging from 3% to 41%. The estimated number of false positives was 31 per 1,000 (95% CI: 10–92 per 1,000), with an assumed baseline risk of 5%. The estimated number of false negatives was 71 per 1,000 (95% CI: 31–141 per 1,000), with an assumed baseline risk of 40%.

Discussion

Our meta-analysis revealed important findings about the diagnostic performance of POCUS for shock evaluation: (1) pooled sensitivity and specificity of POCUS for cardiogenic shock were 86.1% and 95.8%, respectively; (2) pooled sensitivity and specificity of POCUS for obstructive shock were 77.5% and 97.6%, respectively; (3) for cardiogenic shock, the estimated number of false positives was 52 per 1,000, with an assumed baseline risk of 10%, and the estimated number of false negatives was 40 per 1,000, with an assumed baseline risk of 30%; and (4) for obstructive shock, the estimated number of false positives was 31 per 1,000, with an assumed baseline risk of 5%, and the estimated number of false negatives was 71 per 1,000, with an assumed baseline risk of 40%.

Diagnostic Accuracy of POCUS

This meta-analysis demonstrated reasonable diagnostic accuracy of POCUS for both cardiogenic and obstructive shock. POCUS was particularly useful in ruling in these shock types, a finding consistent with those of previous meta-analyses.¹² The primary distinction from earlier meta-analyses is the inclusion of several new studies; however, our results remained robust with these additions. Notably, this analysis demonstrated the certainty of evidence and estimated effect per 1,000 patients tested. For cardiogenic shock, the false-negative rate represents a clinically significant concern, as missed diagnoses may delay critical treatment and worsen outcomes. In obstructive shock, the false-negative rate was even higher, underscoring the critical need for careful clinical interpretation of POCUS findings in both conditions.

Key Indicators of Cardiogenic and Obstructive Shock

Given the noninvasive, repeatable, safe procedure and diagnostic accuracy of POCUS demonstrated in this study, it is a valuable tool for diagnosing cardiogenic shock, which is particularly significant because it can be used even when obtaining a patient’s history, or if performing a physical examination is challenging, especially in potentially serious conditions. Previous studies have identified several key findings for diagnosing cardiogenic shock, including reduced left ventricular ejection fraction (LVEF), regional wall motion abnormality, increased ventricular size, inferior vena cava (IVC) distention, pericardial effusion on the cardiac ultrasound, and B-lines on lung ultrasound.^24–26 For obstructive shock, diagnostic features include pericardial effusion with right heart collapse, dilated IVC in cardiac tamponade, D-sign, and a dilated IVC in pulmonary embolism.^24–27 For emergency physicians, recognizing these findings is critical for accurate shock classification. However, the included studies provided limited information about the underlying etiologies of cardiogenic shock. Although reduced LVEF remains the most common diagnostic criterion, determining whether this represents an acute change or chronic condition can be challenging without prior echocardiographic records. Regional wall motion abnormalities and valvular pathology also serve as important indicators of cardiogenic shock. Assessing regional wall motion abnormalities can be challenging; however, emergency physicians trained in emergency echocardiography can accurately identify these findings.²⁸ In this study, POCUS training methods varied, with examinations primarily performed by emergency medicine physicians possessing baseline echocardiography skills. Training incorporated both a 1-month POCUS program and a curriculum following the International Federation for Emergency Medicine standards.^23,25 False-positive cardiogenic shock diagnoses may occur in patients with chronic heart failure, past myocardial infarction, or cardiomyopathy. Conversely, false negatives can arise from poor image quality due to obesity or lung diseases or overlooked diffuse hypokinesis or subtle abnormalities. As indicated by our findings, approximately 40 false negatives per 1,000 patients were misclassified as not having cardiogenic shock, in high-prevalence settings. Considering the prevalence of cardiogenic shock in this study, this number is not negligible and highlights the potential clinical consequences of false-negative results. Accordingly, a negative POCUS cannot definitively exclude cardiogenic shock. Continued clinical assessment and supplementary diagnostics remain essential to reduce the risk of missed diagnoses. POCUS, when combined with prior clinical findings and other diagnostic tools such as blood tests and CT scans, offers a comprehensive approach for accurate diagnosis. A prior study demonstrated that the addition of clinical findings to POCUS showed an increase in diagnostic accuracy.¹⁰ Thus, it is essential to perform POCUS taking into account clinical examinations such as vital signs and physical examinations.

POCUS is simple; however, diagnosing cardiogenic shock can be difficult for beginners, as detecting decreased LVEF may sometimes be challenging. A prior study showed that introductory training could effectively reduce misclassification rates in LVEF assessment.²⁹ A previous report demonstrated that emergency physicians improved their ability to identify these abnormalities with a short training session on recognizing wall motion abnormalities.³⁰ Therefore, POCUS education may further improve diagnostic accuracy for cardiogenic shock, and promoting POCUS training courses could be essential.

Study Limitations

First, the reference diagnostic methods for cardiogenic shock varied across studies, and definitions of shock were inconsistent. Second, the final diagnostic methods for cardiogenic shock differed, including assessments by either treating physicians or external staff not involved in the studies. Third, the experience level of POCUS performers was different. Although emergency physicians primarily performed POCUS, their training levels and certification status varied significantly, ranging from formally trained/certified practitioners to general emergency physicians without specific accreditation, potentially introducing bias. Fourth, as all of the included studies were conducted overseas, the applicability of findings to Japanese clinical practice remains uncertain due to potential differences in patient demographics, healthcare settings, and available equipment. Fifth, our analysis of obstructive shock included tension pneumothorax (a non-cardiovascular emergency), which prevented a separate evaluation of pulmonary embolism and cardiac tamponade. Further research is required to address these limitations.

Conclusions

The diagnostic accuracy of POCUS for patients with cardiogenic shock was reasonable, especially as a rule-in test.

Disclosures

T. Matoba is a member of Circulation Reports’ Editorial Team and reports research grants from Amgen and Abbott Medical Japan. T.K. received lecture fees from Abbott Japan LLC, AstraZeneca K.K., Boehringer Ingelheim, Ono Pharmaceutical Co., Ltd., Kowa Company, Ltd., and Kyowa Kirin Co., Ltd., and Novartis Pharma K.K. The other authors have no conflicts of interest to disclose.

IRB Information

Not applicable.

Supplementary Files

Supplementary File 1

Supplementary Table.

Data Availability

All data analyzed in this study were extracted from published articles and are available within the article.