Introduction

Hemodynamic instability (HI), which is typically defined as systolic blood pressure (BP) below 90 mm Hg and / or abnormal peripheral perfusion, presents a challenge for emergency medical teams.1,2 In the prehospital setting, managing HI requires rapid assessment, immediate targeted interventions, and timely transport to definitive care. Initial triage of acute patients with HI is usually based on vital signs and 12-lead electrocardiography (ECG).

In recent years, point-of-care ultrasound (POCUS) has become an essential tool for rapidly evaluating hemodynamically unstable patients, particularly in prehospital settings and emergency departments. Paramedics’ decisions in these situations are especially challenging, because they must be made quickly, with limited access to clinical and diagnostic data. However, these decisions directly influence triage, treatment initiation, and final hospital destination selection. In this context, POCUS significantly supplements physical examination by enabling a more targeted evaluation of the causes of instability.

Despite growing interest in this technique, available scientific data remain limited. The number of randomized controlled trials (RCTs) is small, and the existing studies exhibit significant heterogeneity in terms of study populations, protocols, and end points. These factors make it difficult to unequivocally assess the impact of POCUS on clinical outcomes, justifying the need for a narrative review that synthesizes the available evidence.

This review aimed to summarize the current evidence on prehospital ultrasound performed by paramedics on hemodynamically unstable patients, illustrating its impact on clinical decision-making and patient triage with real-world clinical cases. Additionally, the paper presents case studies illustrating practical application of this method and its potential impact on diagnostic and therapeutic processes.

Methods

Study design

The study was prepared as a narrative review of the literature on the use of POCUS in hemodynamically unstable patients, with a particular focus on emergency and prehospital care. A structured literature search was performed in PubMed, Web of Science, and Scopus databases to identify relevant works published between January 2015 and December 2025.

The search strategy combined keywords and MeSH terms related to POCUS and circulatory instability, including “point-of-care ultrasound,” “POCUS,” “hemodynamic instability,” “shock,” “circulatory failure,” “prehospital care,” “emergency medicine,” and “critical care ultrasonography.” Additional studies were identified through manual screening of reference lists from eligible publications. Titles and abstracts were screened for relevance to the review topic. Full-text articles were assessed when eligibility could not be determined from the abstract alone. Eligible publications included original research articles, prospective and retrospective observational studies, systematic reviews, narrative reviews, and clinical practice recommendations evaluating the diagnostic or clinical utility of POCUS in patients with undifferentiated shock or acute HI. Studies focusing exclusively on procedural guidance, isolated organ-specific ultrasound applications without relevance to hemodynamic assessment, veterinary medicine, simulation-based training, or non–English-language publications were excluded.

Due to the anticipated scarcity of RCTs and substantial heterogeneity in patient populations, clinical settings, ultrasound protocols, and reported outcomes, a formal systematic review and meta-analysis was not considered appropriate. Evidence was selected based on methodological quality, clinical relevance, and applicability to emergency and prehospital practice, with particular emphasis on studies evaluating diagnostic pathways and decision-making supported by POCUS.

To supplement the literature review, we included a series of real-life cases of patients presenting with HI in the prehospital setting. We selected these cases based on the availability of POCUS performed by emergency medical providers and analyzed the cases to illustrate the scenarios in which POCUS contributed to rapid diagnosis and immediate clinical decision-making. Consistent with previous reports, we considered POCUS findings to be clinically impactful when they directly influenced management, triage, or therapeutic interventions. Patient consents for the use of case images were obtained, and all patient information has been removed for anonymity.

All ultrasound examinations presented in this case series were performed by paramedics who had successfully completed a certified POCUS training program (according to the regulation of the Polish Minister of Health), and routinely used POCUS in emergency and prehospital practice. A portable Butterfly iQ ultrasound device was used for all examinations. Different POCUS protocols were applied according to the clinical presentation, as detailed in individual case descriptions. The duration of each ultrasound examination was limited to a maximum of 10 minutes. All examinations were routinely recorded in the device memory and subjected to delayed review by an experienced specialist for quality assessment.

We chose the combined approach of a narrative review and a case series to provide an overview of the existing evidence and a practical perspective on the applicability of POCUS in time-critical, resource-limited environments.

Current evidence and clinical application of point-of-care ultrasound in hemodynamic instability

According to the available literature, POCUS is widely used in clinical practice for acute conditions, and several diagnostic protocols using POCUS to diagnose shock have been developed.3-6 The RUSH (Rapid Ultrasound for Shock and Hypotension) protocol is a structured approach that uses POCUS to rapidly assess the cause of shock in critically ill patients.7-9 It is likely the most well-known protocol, and it involves cardiac evaluation and vascular system assessment. The SEARCH (Sonographic Evaluation of Aetiology for Respiratory difficulty, Chest pain, and / or Hypotension) 8ES protocol10 is similar to the RUSH protocol but includes additional assessment of deep vein thrombosis.

In their meta-analysis of 1553 studies, Yoshida et al11 confirmed high sensitivity and positive likelihood ratios of POCUS in identifying the etiology of each type of shock, especially obstructive shock. Volpicelli et al12 analyzed the efficacy of a focused multiorgan POCUS in diagnosing symptomatic, nontraumatic hypotensive patients in an emergency department. They reported perfect concordance between the POCUS diagnosis and the final clinical diagnosis.

Trauma and hypovolemic shock

In the context of trauma, POCUS, particularly in the form of the Focused Assessment with Sonography for Trauma (FAST) protocol and its extended version (eFAST), has become an essential tool in early evaluation of patients with suspected HI (Figure 1).13,14 In the cases of undifferentiated shock following trauma, POCUS enables rapid identification of life-threatening causes of hypovolemia, primarily through the detection of free intraperitoneal or pericardial fluid, as well as thoracic injuries, such as pneumothorax or hemothorax.15 This bedside, repeatable modality is especially valuable in prehospital and emergency settings, where clinical decisions must be made under significant time constraints and with limited diagnostic resources.

Figure 1. Differential diagnosis of hemodynamic instability using point-of-care ultrasound

Abbreviations: FAST, Focused Assessment with Sonography for Trauma; IVC, inferior vena cava; LUQ, left upper quadrant; LV, left ventricle; RUQ, right upper quadrant

Importantly, the use of POCUS in trauma extends beyond diagnosis, and directly informs clinical decision-making. The presence of free fluid in a hemodynamically unstable patient strongly supports the diagnosis of hemorrhagic shock, and may expedite transport to a trauma center, prompt activation of surgical teams, or justify bypassing intermediate facilities. Conversely, a negative result of FAST examination does not exclude ongoing bleeding, highlighting the need for a serial assessment and integration with clinical findings. Available evidence, although heterogeneous and largely observational, consistently suggests that POCUS can shorten the time to definitive care and improve triage accuracy in trauma patients.

In different surveys, eFAST was identified as the most commonly used application of POCUS, reaching comparable sensitivity and specificity between in-hospital and prehospital settings.16 In a 2024 meta-analysis by Lin et al,17 the specificity of detection of free intra-abdominal fluid on POCUS reached 97%, and significantly reduced the time to hospital and operative treatment. Thus, POCUS represents a critical extension of the primary survey in trauma, particularly in patients with suspected hypovolemic shock, providing actionable information that bridges the gap between initial assessment and definitive management.

Cardiogenic shock vs obstructive shock

Both cardiogenic and obstructive shock result in an inadequate blood supply. However, it is important to distinguish between these conditions, because cardiogenic shock is caused by primary cardiac dysfunction, while obstructive shock is caused by extracardiac diseases (Figure 1).

According to the European Society of Cardiology’s current guidelines,18 emergency echocardiography should be performed on all patients presenting with cardiogenic shock or HI to identify the underlying cause. Cardiogenic shock complicates 6%–9% of myocardial infarctions (MIs).19 POCUS may serve as a valuable adjunct in the evaluation of suspected acute coronary syndrome (ACS) by identifying regional wall motion abnormalities, potentially supporting clinical decision-making before ECG changes become apparent. It also differentiates ACS from other causes of chest pain, such as aortic dissection, pericarditis, pulmonary embolism (PE),20 and valvular disease. POCUS can also quickly diagnose mechanical complications of ACS, such as acute mitral regurgitation, papillary muscle rupture, and postinfarction ventricular septal defects.21 According to Sobczyk et al,22,23 POCUS can confirm acute myocardial ischemia and detect other life-threatening cardiac conditions. This allows for proper treatment decisions to be made. Limited echocardiography is also an effective method for distinguishing between ACS and acute aortic syndrome,24 as they often present similarly. POCUS is a valuable tool for diagnosing and managing acute heart failure, particularly detecting pulmonary congestion via lung ultrasound (LUS).25

Obstructive shock is caused by impaired diastolic filling, which results in reduced right ventricular (RV) or left ventricular (LV) preload. Important causes of obstructive shock include pericardial tamponade, tension pneumothorax, acute PE, and aortic dissection. All these conditions can be diagnosed using POCUS.

Pericardial effusions that cause tamponade can arise from various causes. Emergent pericardiocentesis is indicated in the cases of HI, impending deterioration, or cardiac arrest. Clinical Beck triad is not commonly observed, and the most frequently reported symptom is dyspnea. Echocardiography is usually the primary diagnostic tool when pericardial effusion is suspected, as it is accurate, noninvasive, widely available, and feasible also with pocket-size devices.26-28 Studies have shown a high degree of sensitivity and specificity in the detection of pericardial effusion using POCUS, which can be performed also by noncardiologists in emergency settings or at bedside.29-32 Consequently, there is an animated debate on diagnosing tamponade not based on clinical symptoms (Beck triad), but rather on typical echocardiographic findings, including: the presence of pericardial effusion, diastolic RV collapse and systolic right atrial collapse, a plethoric, noncollapsible inferior vena cava (IVC), and exaggerated respiratory cycle changes in mitral and tricuspid valve in-flow velocities as a surrogate for pulsus paradoxus.27

Tension pneumothorax is a life-threatening condition characterized by the accumulation of air under pressure in the pleural space, which leads to lung collapse and mediastinal shift. It is caused by penetrating or blunt thoracic trauma, barotrauma from mechanical ventilation, or iatrogenic injury. A clinical diagnosis is based on signs, such as hypotension, diminished breath sounds on one side, distended neck veins, and tracheal deviation. LUS is now included in most POC protocols, and is the best diagnostic tool for quickly and reliably diagnosing tension pneumothorax.33,34 The widespread use of LUS has been facilitated by the increased availability of hand-held ultrasound devices in hospital and prehospital settings.35,36 Furthermore, LUS use has increased during the COVID-19 pandemic, because it enables clinicians to obtain a wide range of clinical information at the bedside. LUS can be used to diagnose or exclude pneumothorax, guide drainage procedures, and locate the insertion site of a tube. A systematic review of 34 studies involving 8635 participants,37 evaluating the diagnostic accuracy of POCUS in identifying post-traumatic pneumothorax in patients with blunt trauma, confirmed its high sensitivity (96%) and specificity (99%).

In emergency settings, POCUS may provide rapid bedside information suggestive of acute PE, and help assess the presence of HI, thereby supporting clinical decision-making.38 Echocardiography may yield additional prognostic information in higher-risk patients, and can aid in distinguishing acute from chronic RV dysfunction.39 Specific echocardiographic markers of RV dysfunction have the potential to enhance prognostication beyond existing risk models,40,41 as validated in early risk stratification. In hemodynamically unstable patients with acute PE, echocardiographic detection of RV dysfunction indicates the need for thrombolytic administration.42 Several case reports confirm the role of POCUS in diagnosing PE in emergency settings.43,44

Case series

Case 1: point-of-care ultrasound–based diagnosis of myocardial infarction without electrocardiogram

A team of rescuers from the Podhale branch of the Mountain Volunteer Rescue Service was dispatched to a mountain region to assist a 79-year-old man suffering from stenocardia. The rescue team arrived 40 minutes after being notified due to difficult terrain in the area of operation.

The main complaint was severe (8/10) chest pain that was initially exertional and then present at rest. The pain was localized behind the sternum and radiated to the interscapular region. In addition, the patient complained of resting dyspnea that worsened in the supine position. The patient suffered from arterial hypertension, type 2 diabetes, hypothyroidism, hypercholesterolemia, and chronic kidney disease.

Physical examination was performed using the Airway, Breathing, Circulation, Disability, Exposure (ABCDE) approach. The respiratory rate (RR) was 25 breaths per minute, with peripheral SpO2 of 87%. Upon auscultation, symmetrical crackles over the lungs were present. Heart rate (HR) was 80 bpm. BP was initially 130/80 mm Hg, and then dropped to 90/60 mm Hg. The skin was pale and damp, and the Glasgow Coma Scale (GCS) score was 15 points. Twelve-lead ECG recordings could not be made due to dampness at the electrode junction of the defibrillator, which occurred during transport.

POCUS performed with a mobile ultrasound device detected regional LV wall motion abnormalities, including hypokinesis of the anterior wall, apex, and anterior interventricular septum. Six-point LUS showed numerous B-lines that merged to form the white lung sign in the basal parts of the lungs. The diagnosis of anterior wall MI complicated by pulmonary edema was made based on POCUS.

Following a telephone consultation with an on-duty physician, the patient was transported by air ambulance helicopter to a hospital with an invasive cardiology laboratory. Coronary angiography showed proximal occlusion of the left anterior descending artery, and percutaneous coronary angioplasty was successfully performed.

Case 2: acute pulmonary embolism with bradycardia

A medical rescue team was dispatched to the home of an 86-year-old woman who had been found unconscious by her family members. The woman was unresponsive, had trouble breathing, and showed signs of central cyanosis, according to the caller’s account. The interviews conducted with the family members at the scene did not yield any new information regarding the circumstances of the incident or the patient’s medical history.

Upon physical examination, RR was 25 breaths per minute, with indeterminate SpO2. HR was 30 bpm; the radial pulse was not palpable. BP was 70/30 mm Hg on the left arm and 60/30 mm Hg on the right arm. ECG showed a normal heart axis, bradycardia at 30 bpm, and a QR pattern in V1 (a QRS complex with an initial Q wave followed by a prominent R wave, and no terminal S wave; Figure 2A). Following administration of adrenaline, the patient’s HR increased to 80 bpm (Figure 2B). She had altered consciousness, and the GCS score was 10 points. Weakened muscle strength in the extremities was noted.

Figure 2. Case 2; A – 12-lead ECG showing sinus bradycardia of 30 bpm; B – 12-lead ECG after adrenaline infusion: sinus rhythm of 80 bpm, with single premature ventricular beats; C – echocardiography, parasternal long-axis view, showing RV dilatation; D – echocardiography, short axis view with D-sign; E – computed tomography scan showing bilateral pulmonary thrombus (arrows)

Abbreviations: Ao, aorta; ECG, electrocardiography; LA, left atrium; RV, right ventricle; others, see Figure 1

The patient was transferred to an ambulance and POCUS was performed during transport to the nearest hospital emergency department. It revealed RV dilatation and echocardiographic features of right-side heart overload (Figure 2C), including a D-sign in the parasternal short axis view (Figure 2D), McConnell sign in the apical 4-chamber view, and vena cava plethora. A 3-point ultrasound venous compression test was performed and did not show any signs of deep vein thrombosis. LUS showed normal pleural sliding, A-profile, and several small subpleural consolidations bilaterally.

The diagnosis of acute PE was made based mainly on POCUS, and anticoagulant treatment with unfractionated heparin was implemented. A computed tomography scan performed in the hospital emergency department confirmed bilateral massive PE (Figure 2E).

Case 3: an unexpected diagnosis of pneumothorax in a patient recovering from pneumonia

A 2-person emergency medical team was dispatched urgently to a 65-year-old woman experiencing chest pain and shortness of breath.

The main complaints were severe dyspnea and resting retrosternal pain of a pressing nature, without radiation. The patient was hospitalized for bacterial pneumonia and discharged home 2 days before. She had a history of arterial hypertension and coronary artery disease.

Upon physical examination, RR was 26 breaths per minute, with SpO2 of 78%. Upon auscultation, wheezes and rales over the left lung, and muffled crackles over the right lung were present. HR was 110 bpm, and BP 90/60 mm Hg. The skin was pale and damp, and the GCS score was 15 points. The Numerical Rating Scale score was 6 points. The body temperature was 37.1 °C. ECG showed sinus tachycardia of 110 bpm and low voltage of QRS complexes.

POCUS included an echocardiographic assessment and 6-point LUS. Echocardiography revealed a small LV with hyperdynamic systolic function (Figure 3A), no signs of right-side pressure overload, mild pericardial effusion, and narrow IVC with collapsibility of 100%. LUS showed numerous B-lines and several small subpleural consolidations on the left side (Figure 3B). On the right-side, A-profile, abolished pleural sliding, and lung point (Figure 3C) were present. The diagnosis of right-side pneumothorax was made using POCUS.

Figure 3. Case 3; A – echocardiography, short axis view, showing kissing papillary muscles sign; B – lung ultrasound, left side: B-lines and subpleural consolidations (arrows); C – lung ultrasound, right side: A-profile, lung point (arrow)

Abbreviations: see Figures 1 and 2

The prehospital therapeutic management included needle decompression of pneumothorax, implementation of passive oxygen therapy at 15 l per minute, and intravenous fluid implementation. The patient was transferred to the nearest hospital emergency department, where pneumothorax was confirmed and surgically decompressed.

Case 4: severe aortic stenosis complicated by hypovolemic shock

A medical rescue team was dispatched to an 80-year-old woman suffering from general weakness and low BP.

The main complaint was low BP of 80/40 mm Hg. The patient had not ingested food or liquids for 2 days and had vomited. She had arterial hypertension, chronic heart failure, and paroxysmal atrial fibrillation.

Upon physical examination, RR was 18 breaths per minute, with indeterminate SpO2. HR was 60 bpm, and BP 70/40 mm Hg. The skin was pale and damp, mucous membranes were dry, and decreased skin turgor was observed. The radial pulse was weakly palpable. The GCS score was 15 points. Weakened muscle strength in the extremities was noted. Glucose level was 90 mg% (5 mmol/l). ECG showed atrial flutter with ventricular response of 60 bpm, high T waves and high amplitude of QRS complexes in precordial leads indicative of LV hypertrophy (Figure 4A).

Figure 4. Case 4; A – 12-lead ECG: atrial flutter with ventricular response of 60 bpm, high T waves, and high amplitude of QRS complexes in precordial leads indicative of LV hypertrophy; B – echocardiography, parasternal short-axis view: LV hypertrophy and kissing papillary muscles sign; C – echocardiography, parasternal long-axis view: calcified aortic valve (arrow); D – echocardiography, parasternal short-axis view: calcified aortic valve (arrow)

Abbreviations: RA, right atrium; others, see Figures 1 and 2

POCUS was performed according to the RUSH protocol. The following echocardiographic abnormalities were found: severe LV hypertrophy (Figure 4B), a severely calcified, hyperechoic aortic valve with pronounced restriction of cusp mobility (Figure 4C and 4D), and turbulent flow through the aortic valve visualized using the color Doppler option. A hyperkinetic LV with kissing papillary muscles sign, as well as a poorly filled IVC with inspiratory collapse of more than 50%, were indicative of significant hypovolemia. Six-point LUS showed symmetrical pleural sliding and A-profile. There was no peritoneal or pleural free fluid. The abdominal aorta was of normal size. A diagnosis of severe hypovolemia in a patient with suspected aortic stenosis was made using POCUS.

The patient was immediately transferred to the nearest emergency department. Further treatment included 3 intravenous boluses (250 ml each) of crystalloid solution, which improved peripheral perfusion and increased BP to 130/80 mm Hg. The patient was then transferred to a cardiology department for a thorough evaluation of the aortic stenosis significance and potential eligibility for surgical or transcatheter treatment.

Case 5: cardiac tamponade in a bone marrow recipient

An emergency medical team was called by a family doctor to a 20-year-old patient with an initial diagnosis of bronchitis and increasing shortness of breath, reduced exercise tolerance, and decreasing SpO2. The patient underwent bone marrow transplantation for acute leukemia and used immunosuppressive drugs.

Upon physical examination, RR was 20 breaths per minute, with SpO2 of 86%. HR was 110 bpm, and BP 110/70 mm Hg. The skin was pale and damp, the GCS score 15 points, and body temperature was 37 °C. ECG showed sinus tachycardia of 110 bpm and alternating amplitude of QRS complexes (Figure 5A).

Figure 5. Case 5; A –12-lead ECG: sinus tachycardia and alternating amplitude of QRS complexes; B – echocardiography, subcostal view: pericardial fluid (arrow) causing RV collapse

Abbreviations: see Figures 1 and 2

POCUS included echocardiography and LUS. LUS showed bilateral pleural sliding and A-profile. There were no consolidations or pleural free fluid. Subcostal view revealed a large amount of pericardial fluid, with echocardiographic signs of RV collapse (Figure 5B). A diagnosis of cardiac tamponade was made using POCUS.

The patient was immediately transferred to the nearest emergency department. After initial stabilization, the patient was urgently transported to a higher-referral hospital, where tamponade was decompressed and treatment for acute infective pericarditis was initiated.

Discussion

Correct initial assessment and management of patients with shock or hypotension are crucial, as prompt treatment improves prognosis.1,2 The optimal treatment differs depending on the cause. However, patients in a prehospital setting often present with atypical symptoms, such as shortness of breath or chest pain, which may indicate various life-threatening conditions requiring different management.

Standard evaluation of a patient in a prehospital setting includes taking medical history, performing structured physical examination according to the ABCDE scheme, and evaluating ECG results. With the widespread availability of ultrasound technology in emergency departments, specific, goal-directed ultrasound examinations have been reported to help with a rapid diagnosis of nontraumatic causes of hypotension in the early evaluation of critically ill patients.3-9

This narrative review presents a series of cases in which POCUS use in the prehospital setting enabled diagnosis, immediate targeted treatment, and appropriate hospital selection, significantly increasing the patients’ chances of survival. The case series presented here supports the hypothesis that trained paramedics can successfully use POCUS in the prehospital setting. In the first case, MI was suspected due to the presence of regional wall motion abnormalities and could not be confirmed on site due to the lack of ECG availability. POCUS helped diagnose acute PE (case 2) and cardiac tamponade (case 5). Case 4 is particularly interesting, because ultrasound examination revealed severe hypovolemia in a patient with aortic stenosis. Each case report showed that POCUS in the hands of trained paramedics supports the diagnostic and therapeutic processes, and often influences treatment decisions (Table 1). It should be highlighted that the presented description of clinical cases is strictly observational and based on a small sample size. Therefore, the conclusions drawn from this publication cannot be broadly generalized, though our observations are consistent with the global literature in this field.1-9

Table 1. Summary of point-of-care-ultrasound findings in the presented cases

Case

Echocardiography

Lung ultrasound

Veins

Preliminary diagnosis

1

RWMA: hypokinesis of the anterior wall, apex, and anterior IVS

B-lines in basal parts, bilaterally

–

Anterior myocardial infarction

2

RV overload: RV dilatation, D-sign, McConnell sign

Normal pleural sliding, A-profile

Negative venous compression test, vena cava plethora

Acute pulmonary embolism

3

Hyperdynamic LV, mild pericardial effusion

  • On the left: B-lines and small subpleural consolidations,
  • On the right: A-profile, abolished pleural sliding lung point

Narrow IVC, collapsibility 100%

Pneumothorax

4

Hyperdynamic LV with kissing papillary muscles sign, hyperechoic aortic AV with restriction of cusp mobility

Normal pleural sliding, A-profile, no pleural effusion

Narrow IVC, collapsibility >50%

Hypovolemia in a patient with possible aortic stenosis

5

Large amonut of pericardial fluid, echocardiographic signs of RV collapse

Normal pleural sliding, A-profile

–

Cardiac tamponade

Abbreviations: AV, aortic valve; IVS, interventricular septum; RWMA, regional wall motion abnormality; others, see Figures 1 and 2

Previous studies suggest that paramedics can acquire basic POCUS skills following focused training programs, although the duration, content, and competency assessment methods vary considerably across studies.45-50 Reported training interventions have ranged from brief didactic and hands-on sessions to more structured educational programs, with competency typically assessed through image acquisition and interpretation performance. Simplified examination protocols, such as the Focused Assessed Transthoracic Echocardiography, RUSH, and eFAST, have been shown to be feasible in the prehospital setting, and may provide clinically relevant information to support decision-making.7-9,16 The increasing availability of portable ultrasound devices has expanded access to diagnostic imaging in resource-limited and prehospital environments. In this context, POCUS may enhance paramedic assessment by providing additional diagnostic information that can be integrated with clinical findings to guide patient management and transport decisions.6,31,32,44

As any other diagnostic method, POCUS has its limitations. It is important to acknowledge that POCUS is not a universal diagnostic tool, and its effectiveness depends on the operator. Using handheld ultrasound devices in prehospital care is associated with technical limitations that can affect image acquisition, interpretation, and diagnostic accuracy. Unlike high-end hospital ultrasound systems, portable devices often have reduced imaging capabilities. These include lower spatial and temporal resolution, limited penetration in patients with obesity, and inferior visualization of deep anatomical structures. A small screen size can further hinder assessment of detailed images, especially during rapid decision-making in time-critical situations. Image quality can be substantially compromised by challenging environmental conditions commonly encountered in prehospital medicine. Nevertheless, handheld devices reflect the reality of contemporary prehospital and emergency care environments, where portability and immediate availability are critical.

Previous studies have described situations in which POCUS in the prehospital or emergency setting yielded limited or misleading information, particularly in technically challenging patients, in early disease stages, or when image acquisition was suboptimal.51-53 In such circumstances, ultrasound may prolong the diagnostic process without providing actionable information, and misinterpretation may lead to false-negative or false-positive results. The frequency of reported “missed diagnoses” depends on how error frequency is assessed. A retrospective review of all admissions confirmed missed or delayed diagnoses in approximately 8%–10% of the cases.52

Considering all the limitations and potential sources of error mentioned above, it is important to note that ultrasound findings should always be interpreted alongside the patient’s clinical presentation. Equivocal or technically limited examinations should not lead to overconfidence in diagnosis or inappropriate changes in management. When used appropriately, POCUS can improve diagnostic accuracy and patient triage while ensuring timely treatment and transport.

Safety considerations

The use of POCUS in hemodynamically unstable patients should be guided by the principle that ultrasound serves as an adjunct to, rather than a replacement for, standard clinical assessment and time-critical interventions. In the prehospital setting, image acquisition must not delay resuscitative measures, definitive treatment, or transport to an appropriate receiving facility. In particular, a “scan-and-go” rather than a “stay-and-play” approach should be adopted whenever prolonged on-scene assessment could compromise timely access to definitive care. Examinations should therefore be focused, goal-directed, and limited to questions that are expected to influence immediate clinical decision-making.

Limitations

This study has several important limitations that should be acknowledged. First, as a narrative review, it is inherently subject to a degree of subjectivity in the selection, interpretation, and synthesis of the available evidence. Unlike in a systematic review, the methodology does not follow a strictly predefined protocol for study inclusion, which may increase the risk of incomplete literature capture and limit reproducibility. The potential for selection bias must be considered. The included studies vary substantially in terms of design, patient populations, clinical settings, and POCUS protocols, and the choice of studies may have influenced the overall conclusions. Additionally, the available body of evidence is dominated by observational data, with a limited number of RCTs, further restricting the strength of inferences that can be drawn.

Second, POCUS is inherently operator-dependent. Image acquisition, interpretation, and subsequent clinical decision-making may vary according to the examiner’s experience and training. While all examinations were performed by professionals experienced in POCUS, interoperator variability remains a possibility. Furthermore, handheld ultrasound devices may have technical limitations, as compared with high-end cart-based systems. Integrating POCUS findings into clinical reasoning carries a risk of cognitive biases, particularly anchoring bias. This occurs when early ultrasound findings disproportionately influence subsequent diagnostic thinking.

Finally, the incorporation of real-life case vignettes, while valuable for illustrating practical applications of POCUS in time-critical settings, does not constitute evidence of clinical effectiveness. The cases were purposively selected to demonstrate distinct diagnostic pathways and applications of POCUS in hemodynamically unstable patients, and do not constitute a consecutive patient series. Therefore, they should be interpreted as complementary to, rather than a substitute for, higher-quality evidence.

Taken together, these limitations underscore the need for cautious interpretation of the findings and highlight the importance of further prospective and controlled studies to better define the clinical impact of POCUS in hemodynamically unstable patients.

Conclusions

POCUS is a valuable addition to the standard diagnostic assessment of patients with undifferentiated HI, particularly in prehospital and early emergency settings. POCUS provides rapid bedside information on potentially life-threatening conditions, such as hemorrhage, cardiac tamponade, pneumothorax, and severe ventricular dysfunction. This information supports timely clinical decision-making, triage, and targeted management.

Successful integration of POCUS into emergency medical services requires adequate operator training, standardized protocols, and interpretation of ultrasound findings within the broader clinical context. Importantly, POCUS should complement, rather than replace, established diagnostic pathways. Further research is needed to standardize POCUS protocols for HI, define competency requirements for nonphysician providers, and evaluate the impact of emerging technologies on prehospital care.