Diagnostic Accuracy of Point-of-Care Ultrasound for Shock

A Systematic Review and Meta-Analysis

Takuo Yoshida; Takuya Yoshida; Hisashi Noma; Takeshi Nomura; Akihiro Suzuki; Takahiro Mihara

Crit Care. 2023;27(200)

Abstract and Introduction

Abstract

Background: Circulatory failure is classified into four types of shock (obstructive, cardiogenic, distributive, and hypovolemic) that must be distinguished as each requires a different treatment. Point-of-care ultrasound (POCUS) is widely used in clinical practice for acute conditions, and several diagnostic protocols using POCUS for shock have been developed. This study aimed to evaluate the diagnostic accuracy of POCUS in identifying the etiology of shock.

Methods: We conducted a systematic literature search of MEDLINE, Cochrane Central Register of Controlled Trials, Embase, Web of Science, Clinicaltrial.gov, European Union Clinical Trials Register, WHO International Clinical Trials Registry Platform, and University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) until June 15, 2022. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and assessed study quality using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Meta-analysis was conducted to pool the diagnostic accuracy of POCUS for each type of shock. The study protocol was prospectively registered in UMIN-CTR (UMIN 000048025).

Results: Of the 1553 studies identified, 36 studies were full-text reviewed, and 12 studies with 1132 patients were included in the meta-analysis. Pooled sensitivity and specificity were 0.82 [95% confidence interval (CI) 0.68–0.91] and 0.98 [95% CI 0.92–0.99] for obstructive shock, 0.78 [95% CI 0.56–0.91] and 0.96 [95% CI 0.92–0.98] for cardiogenic shock, 0.90 [95% CI 0.84–0.94] and 0.92 [95% CI 0.88–0.95] for hypovolemic shock, and 0.79 [95% CI 0.71–0.85] and 0.96 [95% CI 0.91–0.98] for distributive shock, respectively. The area under the receiver operating characteristic curve for each type of shock was approximately 0.95. The positive likelihood ratios for each type of shock were all greater than 10, especially 40 [95% CI 11–105] for obstructive shock. The negative likelihood ratio for each type of shock was approximately 0.2.

Conclusions: The identification of the etiology for each type of shock using POCUS was characterized by high sensitivity and positive likelihood ratios, especially for obstructive shock.

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Abstract and Introduction
Background
Methods
Results
Discussion
Conclusions
References

Table 1. Study characteristics
Study	Design, no. of patients (location)	Clinical setting	Definition of circulatory failure	US protocol	US Physician	Reference standard
Bagheri-Hariri et al. [40]	Prospective Cohort, one center, 25 patients (Iran)	Emergency department	SBP < 90 mmHg or shock index^a > 1.0 with clinical hypoperfusion symptoms	Multi-organ POCUS (observed in order: heart/IVC, jugular veins, thoracic and abdominal cavities, lungs/deep veins, aorta)^b	Emergency physicians with credentials for the emergency department ultrasound	Clinical diagnosis using all medical information
Ghane et al. [33]	Prospective Cohort, one center, 77 patients (Iran)	Emergency department	SBP < 100 mmHg or shock index^a > 1.0	Multi-organ POCUS (observed in order: heart/IVC, jugular veins, thoracic and abdominal cavities, lungs/deep veins, aorta) ^b	An emergency physician with five years of experience with more than 200 ultrasonographic exams per year	Clinical diagnosis after admission to the medical units (internal medicine, cardiology, or surgery) by board-certified specialists
Shokoohi et al. [43]	Prospective Cohort, one center, 118 patients (USA)	Emergency department	SBP < 90 mmHg after an initial fluid resuscitation (> 1L of normal saline)	Multi-organ POCUS (no order specified: heart, IVC, thoracic and abdominal cavities, and lung)	An ultrasound-trained attending physician (including ultrasound fellows) with extensive experience in emergency and critical care ultrasound	Clinical diagnosis by chart review by two board-certified intensivists, blinded to the results of POCUS
Agmy et al. [41]	Unknown, one center, 63 patients (Egypt)	Intensive care unit	Circulatory shock patients (definition was unknown)	Multi-organ POCUS (observed in order: heart and lung)^c	Unclear	Clinical diagnosis using all medical information
Nazerian et al. [35]	Prospective Cohort, two center, 105 patients (Italy)	Emergency department	SBP < 90 mmHg or a drop of SBP > 40 mmHg for more than 15 min, with signs of end-organ hypoperfusion (cold extremities, UO < 30 mL/h, altered mental status, profound asthenia with fatigue and malaise, or respiratory distress), with suspected PE	Multi-organ POCUS (no order specified: heart and deep veins)	Sonographers with more than 2 years' experience in cardiac and venous US on critically ill patients	Clinical diagnosis by an expert in PE who independently reviewed all the available clinical and imaging data including multidetector computed tomography pulmonary angiography
Elbaih et al. [38]	Prospective Cohort, one center, 100 patients (Egypt)	Emergency department	Unstable polytrauma patients (definition of unstable was unknown)	Multi-organ POCUS (observed in order: heart/IVC, jugular veins, thoracic and abdominal cavities, lungs/deep veins, aorta)^b	Unclear	Clinical diagnosis using all medical information
Tesfaye et al. [42]	Prospective Cohort, one center, 93 patients (Ethiopia)	Emergency department	Hypotension (definition of hypotension was unknown)	Multi-organ POCUS (observed in order: heart/IVC, jugular veins, thoracic and abdominal cavities, lungs/deep veins, aorta)^b	Unclear	Clinical diagnosis after full evaluation
Daley et al. [37]	Prospective Cohort, six centers, 136 patients (USA)	Emergency department	Tachycardia and/or hypotension with suspected PE (definition of tachycardia and hypotension was unknown)	Heart including the measurement of TAPSE^d	Emergency physicians or study investigators (including medical students) trained in FOCUS	Computed tomography angiography
Rahulkumar et al. [36]	Prospective Cohort, one center, 97 patients (India)	Emergency department	SBP < 90 mmHg and shock index^a > 1.0	Multi-organ POCUS (observed in order: heart/IVC, jugular veins, thoracic and abdominal cavities, lungs/deep veins, aorta) ^b	An emergency physician expert in emergency medicine ultrasound	Clinical diagnosis using all medical information by the consultants of medicine or surgery department
Javali et al. [39]	Prospective Cohort, one center, 100 patients (India)	Emergency department	SBP < 90 mmHg and shock index ^a > 1 with the presence of at least one of the following signs or symptoms of hypoperfusion unresponsiveness, altered mental status, syncope, respiratory distress, generalized fatigue, severe chest pain or abdominal pain	Multi-organ POCUS (no order specified: heart, lung, free fluid in the peritoneal cavity, aorta, IVC, and femoral vein)	A trained emergency physician (unclear regarding ultrasound experience)	Clinical diagnosis after admission to the medical units (internal medicine, cardiology, or surgery) by board-certified specialists, blind to the diagnoses in the emergency department
Keefer et al. [32]	Prospective Cohort, six centers, 135 patients (North America and South Africa)	Emergency department	Sustained SBP < 100 mmHg or shock index^a > 1.0	Multi-organ POCUS (observed in order: heart/IVC, jugular veins, thoracic and abdominal cavities, lungs/deep veins, aorta) ^b	POCUS-trained emergency physicians	Clinical diagnosis by chart review by two clinicians, blinded to the initial sonographer, and point-of-care ultrasonography findings and diagnosis
Zieleskiewicz et al. [34]	Prospective Cohort, one center, 83 patients (France)	General ward	MAP < 65 mmHg or HR < 40 bpm or HR > 120 bpm or UO < 50 ml/4 h	Multi-organ POCUS (no order specified: heart, IVC, lung, thoracic cavity, and the deep veins if required)	ICU physicians trained in ultrasound	Clinical diagnosis by chart review including physical examinations and blood and imaging tests by two physicians blinded of the initial diagnoses made at the bedside

SBP, systolic blood pressure; MAP, mean arterial pressure; HR, heart rate; bpm, beat per minutes; UO, urine output; PE, pulmonary embolism; US, ultrasound; TAPSE, tricuspid annular plane systolic excursion; and IVC, inferior vena cava
^aShock index is defined as the heart rate divided by systolic blood pressure
^bDescribed as RUSH (rapid ultrasound for shock and hypotension) exam in this study
^cDescribed FALLS (fluid administration limited by lung sonography) protocol in this study
^dDescribed FOCUS (focused cardiac ultrasound) in this study

Table 2. QUADAS-2 results
Study	Risk of bias				Applicability concerns
Study	Patient selection	Index test	Reference standard	Flow and timing	Patient selection	Index test	Reference standard
Bagheri-Hariri et al. [40]	Low	Low	Low	High	Low	Low	Low
Ghane et al. [33]	High	Low	Low	High	Low	Low	Low
Shokoohi et al. [43]	High	Low	Low	Low	Low	Low	Low
Agmy et al. [41]	Unclear	Low	Low	Unclear	Unclear	Low	Low
Nazerian et al. [35]	Low	Low	Low	High	Low	Low	Low
Elbaih et al. [38]	High	Low	Low	Low	Low	Low	Low
Tesfaye et al. [42]	Unclear	Low	Low	Unclear	Unclear	Low	Low
Daley et al. [37]	Low	High	Low	Low	Low	Low	Low
Rahulkumar et al. [36]	Low	Low	Low	Low	Low	Low	Low
Javali et al. [39]	High	Low	Low	Low	Low	Low	Low
Keefer et al. [32]	Low	Low	Low	High	Low	Low	Low
Zieleskiewicz et al. [34]	Low	Low	Low	Low	Low	Low	Low

Table 3. Sensitivities, specificities, AUROCs, and likelihood ratios by shock subtype
Shock type	No. of patients (study)	Sensitivity	Specificity	Area under the ROC curve	Positive likelihood ratio	Negative likelihood ratio
Obstructive	810 (9)	0.82 (0.68–0.91)	0.98 (0.92–0.99)	0.95 (0.78–0.97)	40 (11–105)	0.20 (0.10–0.33)
Cardiogenic	828 (9)	0.78 (0.56–0.91)	0.96 (0.92–0.98)	0.96 (0.86–0.97)	19 (7.1–40)	0.24 (0.09–0.47)
Hypovolemic	688 (9)	0.90 (0.84–0.94)	0.92 (0.88–0.95)	0.96 (0.87–0.96)	12 (7.3–18)	0.11 (0.07–0.17)
Distributive	594 (8)	0.79 (0.71–0.85)	0.96 (0.91–0.98)	0.86 (0.75–0.96)	23 (9.3–49)	0.22 (0.16–0.30)
Mixed	291 (4)	0.80 (0.61–0.91)	0.96 (0.89–0.99)	0.95 (0.76–0.97)	20 (7.9–49)	0.21 (0.10–0.40)