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Home , Renal ultrasonography, Review of systems

REVIEW

Point-of-Care Ultrasonography for Primary Care Physicians and General Internists

Anjali Bhagra, MBBS; David M. Tierney, MD; Hiroshi Sekiguchi, MD; and Nilam J. Soni, MD, MSc

Abstract

Point-of-care ultrasonography (POCUS) is a safe and rapidly evolving diagnostic modality that is now utilized by health care professionals from nearly all specialties. Technological advances have improved the portability of equipment, enabling ultrasound imaging to be executed at the bedside and thereby allowing internists to make timely diagnoses and perform ultrasound-guided procedures. We reviewed the liter- ature on the POCUS applications most relevant to the practice of internal medicine. The use of POCUS can immediately narrow differential diagnoses by building on the clinical information revealed by the tradi- tional and refining clinical decision making for further management. We describe 2 common patient scenarios (heart failure and sepsis) to highlight the impact of POCUS performed by internists on efficiency, diagnostic accuracy, resource utilization, and radiation exposure. Using POCUS to guide procedures has been found to reduce procedure-related complications, along with costs and lengths of stay associated with these complications. Despite several undisputed advantages of POCUS, barriers to implementation must be considered. Most importantly, the utility of POCUS depends on the experience and skills of the operator, which are affected by the availability of training and the cost of ultrasound devices. Additional system barriers include availability of templates for documentation, electronic storage for image archiving, and policies and procedures for quality assurance and billing. Integration of POCUS into the practice of internal medicine is an inevitable change that will empower internists to improve the care of their patients at the bedside. ª 2016 Mayo Foundation for Medical Education and Research n Mayo Clin Proc. 2016;91(12):1811-1827

oint-of-care ultrasonography (POCUS) it allows only listening to the human body is a safe and rapidly evolving diagnostic (steth ¼ chest, phone ¼ sound), rather than modality. Traditionally, ultrasonogra- truly looking inside the body (scope ¼ to From the Division of P General Internal Medicine phy has been used by imaging specialists, look in). However, as true “scopes,” portable (A.B.) and Division of Pul- such as radiologists and cardiologists; however, ultrasound devices can generate high-quality monary and Critical Care it is now utilized by health care professionals images revealing the structure and function Medicine (H.S.), Depart- from nearly all specialties. Technological ad- of organs.4 The traditional bedside physical ment of Medicine, Mayo Clinic, Rochester, MN; vances have improved portability and minia- examination has been on the decline within Abbott Northwestern turization of equipment, allowing ultrasound internal medicine for several years for various Hospital, Medical Educa- imaging at the bedside to make timely diagno- reasons.5-9 This increase in ambiguity in diag- tion Department, Minne- apolis, MN (D.M.T.); and ses and guide procedures. Over the past several nosis is potentially unsettling to internal med- Section of Hospital Medi- years, there has been emerging interest in the icine physicians who see a variety of complex cine, South Texas Veter- routine use of POCUS to potentially expedite presentations and want to “do no harm.” ans Health Care System 1 and Division of Pulmonary and provide cost-efficient, high-value care. Globally, medical education still emphasizes Diseases and Critical Care This technology has been touted as the “vi- teaching traditional physical examination; Medicine, University of sual ” of the 21st century.2,3 The however, no patient outcomes data justify Texas Health Science Center, San Antonio, TX stethoscope, developed 200 years ago, is the application of physical examination tech- (N.J.S.). classic icon for the traditional diagnostic phys- niques learned for commonly encountered ical examination and is still the most widely clinical conditions. As an example, little data used tool to examine patients at the bedside. exist regarding an evaluation of central venous It is interesting to note, however, that the pressure using jugular venous distention in a stethoscope is truly a “stethophone” because morbidly obese patient. Moreover, many

Mayo Clin Proc. n December 2016;91(12):1811-1827 n http://dx.doi.org/10.1016/j.mayocp.2016.08.023 1811 www.mayoclinicproceedings.org n ª 2016 Mayo Foundation for Medical Education and Research MAYO CLINIC PROCEEDINGS

important cardiopulmonary abnormalities that ultrasonography can expeditiously assess are easily and rapidly detected by POCUS, global LV and right ventricular function and such as pericardial fluid, left ventricular (LV) detect the presence of a .25 systolic dysfunction, and pleural effusion, are Other common POCUS applications include often missed by traditional physical examina- vascular, musculoskeletal, sinus, ocular, nerve, tion. It is conceivable that patients’ increas- thyroid, gallbladder, , spleen, renal, testic- ingly complex medical conditions, ular, and bladder imaging (Figure 1). physicians’ declining physical examination Several medical and surgical subspecialties skills, and society’s expectation for higher have adopted POCUS protocols to rule in or standards of medical care are all leading to rule out certain conditions using an algo- increased utilization of POCUS for more accu- rithmic approach. Common protocols include rate bedside assessments of patients. BLUE (Bedside Lung Ultrasound in Emer- POCUS can immediately narrow the gency) for acute respiratory failure,26 FAST by building on clinical (Focused Assessment with Sonography in information revealed by the history and phys- Trauma) for peritoneal free fluid,27 RUSH ical examination10,11 and refine clinical deci- (Rapid Ultrasound for and Hypoten- sion making for further work-up and sion) for shock,28,29 and CLUE (Cardiovascu- treatment.12 Recent studies have found that lar Limited Ultrasound Examination) for heart clinical management involving the early use failure.30 These protocols offer a logical of POCUS accurately guides diagnosis, signifi- POCUS workflow for specific clinical sce- cantly reduces physicians’ diagnostic uncer- narios and provide a foundation to integrate tainty, and also changes management and POCUS findings into clinical decision making. resource utilization.13 From a patient perspec- POCUS is not simply a diagnostic algorithm tive, “very low” discomfort was reported but rather a tool used by a skilled clinician at the during POCUS of the heart, lungs, and deep bedside to guide clinical decision making in real , and most patients agreed to be evalu- time. Although almost any diagnostic evalua- ated with POCUS in an emergency depart- tion can be aided by POCUS (Figure 1, Table), ment.14 Additionally, use of POCUS in the we will describe 2 common patient scenarios emergency department has been reported to to highlight the impact of POCUS on efficiency, improve patient satisfaction and short-term diagnostic accuracy, resource utilization, radia- health care resource utilization.15-17 tion exposure, and patient satisfaction.

LITERATURE REVIEW AND CLINICAL CASE 1 APPLICATIONS A 41-year-old man with hypertension, type 2 POCUS can be helpful in a variety of common mellitus, and presented to the clinical conditions by quickly identifying outpatient clinic with worsening shortness of abnormalities that may not be revealed by a breath. The had begun traditional physical examination.2 For instance, abruptly while the patient was at work in a cab- consider the evaluation of a patient presenting inet woodworking shop. He had been evaluated with unexplained dyspnea. In these patients, in an urgent care clinic 1 week before presenta- POCUS of the lungs can rapidly detect pleural tion and treated with a short course of cortico- effusions, pulmonary (B lines, a type steroids and inhaled albuterol. His symptoms of comet tail artifact),18 pneumonia (consolida- improved initially but subsequently worsened. tion with dynamic air bronchograms),19 or He reported frequent ankle swelling that had pneumothorax (absence of pleural sliding and recently increased. A review of systems revealed presence of a lung point sign).20 loud at night but no , , Other conditions readily detected with paroxysmal nocturnal dyspnea, recent travel/ POCUS include abdominal aortic aneu- immobilization, or infectious symptoms. rysms,21 deep venous thromboses,22 and peri- toneal free fluid.23 Central venous pressure can be estimated by assessing the inferior Traditional Physical Examination vena cava (IVC) or internal jugular size Traditional physical examination revealed the and collapsibility.24 Focused cardiac following:

1812 Mayo Clin Proc. n December 2016;91(12):1811-1827 n http://dx.doi.org/10.1016/j.mayocp.2016.08.023 www.mayoclinicproceedings.org POINT-OF-CARE ULTRASONOGRAPHY

FIGURE 1. Internal medicine point-of-care ultrasonography applications. IVC ¼ inferior vena cava.

d : , 36.2 C; rate, d Cardiovascular: Distant , no 90 beats/min; , 128/85 mm murmur, neck veins not visible, mild bilat- Hg; , 15 breaths/min; oxygen eral edema of the ankles saturation, 95%; body mass index (calcu- d : Protuberant, no palpable hepa- lated as weight in kilograms divided by tosplenomegaly, no or fluid height in meters squared), 31 kg/m2 wave d Head, ears, eyes, nose, and throat: Mild d Skin: No abnormalities bilateral on over maxillary sinuses Differential Diagnosis. On physical examina- d Pulmonary: Distant lung sounds, occasional tion, the differential diagnosis includes asthma expiratory wheezing bilaterally exacerbation, congestive heart failure, allergic

Mayo Clin Proc. n December 2016;91(12):1811-1827 n http://dx.doi.org/10.1016/j.mayocp.2016.08.023 1813 www.mayoclinicproceedings.org 1814

TABLE. Test Characteristics of Physical Examination vs Point-of-Care Ultrasonography Physical examination31 Point-of-care ultrasonography Test characteristics Finding Sensitivity Specificity LR+ LR Finding Sensitivity Specificity LR+ LR Pulmonary Pleural effusion Percussion dullness 89% 81% 4.8 0.1 Pleural fluid visualization32 93% 96% 23 0.07 Decreased breath sounds 88% 83% 5.2 0.1 19%-64% 82%-94% 3.4 NS B lines (bilateral)33 94% 92% 10.4 0.06 Pneumonia Bronchial breath sounds 14% 96% 3.3 NS Consolidation pattern34,35 94%-95% 90%-96% 13.5 0.06 aoCi Proc. Clin Mayo 4%-16% 96%-99% 4.1 NS Crackles 19%-67% 36%-94% 1.8 0.8 Cardiac Elevated LV filling 4th Heart sound 37%-71% 50%-70% NS NS PCWP 17 if 36 n pressures IVC >2.0 75% 83% 4.4 0.3 eebr2016;91(12):1811-1827 December IVCCI <45%36 83% 71% 2.9 0.24 Elevated CVP Neck vein inspection 47%-92% 93%-96% 9.7 0.3 For CVP >10 mm Hg: > 37 >8cmH2O IVC size 2cm 73% 85% 4.9 0.32 with IVCCI <50%38 87% 82% 4.8 0.16

For CVP <10 mm Hg: IVC <2cm39 85% 81% 4.4 0.2 with IVCCI >50%39 47% 77% 2.1 0.7 IJV aspect ratio for CVP <840 78% 77% 3.5 0.3 Reduced ejection 3rd Heart sound 11%-51% 85%-98% 3.4 0.7 LV systolic dysfunction41-43 84%-91% 85%-88% 6.5 0.14 n < http://dx.doi.org/10.1016/j.mayocp.2016.08.023 fraction 50% Congestive heart Crackles 12%-23% 88%-96% NS NS B lines, bilateral26 97% 95% 19.4 0.03 failure Elevated JVP 10%-58% 96%-97% 3.9 NS For CVP >10 mm Hg: PROCEEDINGS CLINIC MAYO IVC size >2cm37 73% 85% 4.9 0.32 www.mayoclinicproceedings.org with IVCCI <50%38 87% 82% 4.8 0.16 Abdominojugular test 55%-84% 83%-98% 8.0 0.3 Edema 10% 93%-96% NS NS CVP <10 mm Hg: IVC <2cm39 85% 81% 4.4 0.2 with IVCCI >50%39 47% 77% 2.1 0.7 Continued on next page www.mayoclinicproceedings.org ON-FCR ULTRASONOGRAPHY POINT-OF-CARE aoCi Proc. Clin Mayo n eebr2016;91(12):1811-1827 December

TABLE. Continued

Physical examination31 Point-of-care ultrasonography

n Test characteristics Finding Sensitivity Specificity LR+ LR Finding Sensitivity Specificity LR+ LR http://dx.doi.org/10.1016/j.mayocp.2016.08.023 Abdomen Percussion 61%-92% 30%-43% NS NS Hepatomegaly 82% 90% 8.2 0.2 (13 or 15.5 cm)44 39%-71% 56%-85% 1.9 0.6 Percussion 25%-85% 32%-94% 1.7 0.7 Splenomegaly45 100% 74% 3.8 0 Palpation 18%-78% 89%-99% 8.5 0.5 Bladder volume Palpation 82% 56% 1.9 0.3 US bladder volume 96% 75% 3.84 0.05 >400 mL >600 mL (transverse diameter >9.7 cm)46 Bulging flanks 73%-93% 44%-70% 1.9 0.4 Ascites visualization47 96% 82% 32 0.04 Flank dullness 80%-94% 29%-69% NS 0.3 Shifting dullness 60%-87% 56%-90% 2.3 0.4 Fluid wave 50%-80% 82%-92% 5.0 0.5 Vascular Lower extremity DVT Calf swelling >2 cm 61%-67% 69%-71% 2.1 0.5 Compression venous 96% 97% 32 0.04 Homans sign 10%-54% 39%-89% NS NS ultrasonography48 Wells score (high probability) 38%-87% 71%-99% 6.3 NA

CVP ¼ central venous pressure; DVT ¼ deep vein thrombosis; IJV ¼ internal jugular vein; IVC ¼ inferior vena cava; IVCCI ¼ IVC collapsibility index; JVP ¼ ; LR+ ¼ positive likelihood ratio; LR¼negative likelihood ratio; LV ¼ left ventricle; NA ¼ not applicable; NS ¼ not significant; PCWP ¼ pulmonary capillary wedge pressure; US ¼ ultrasound. 1815 MAYO CLINIC PROCEEDINGS

pneumonitis secondary to wood dust, pneu- d Pulmonary: Lung sliding bilaterally monia, and pulmonary hypertension due to throughout (Supplemental Video 1, available obstructive . online at http://www.mayoclinicproceedings. org), multiple bilateral B lines (3 per inter- Plan With Traditional Physical Examination space) in upper and lower lung fields Alone. For patients with the aforementioned (Figure 2,B;Supplemental Video 1), small findings on traditional physical examination, bilateral pleural effusions with associated the following steps would be taken: atelectasis (Figure 2,C;Supplemental Video 2, available online at http://www. d Outpatient chest mayoclinicproceedings.org) d Addition of inhaled glucocorticoid and d Cardiovascular: Measurement of IVC was continuation of albuterol for asthma 2.8 cm with less than 50% collapse on inspi- d Follow-up in 3 to 5 days if no improvement ration (Figure 2,C;Supplemental Video 2), noted no pericardial effusion, LV wall thickness of 2 cm septal and 1.9 cm posterior, LV sys- POCUS-Assisted Physical Examination tolic function severely reduced (Figure 2, POCUS-assisted physical examination D; Supplemental Video 3, available online revealed the following: at http://www.mayoclinicproceedings.org), d Head, ears, eyes, nose, and throat:Nofluid no major mitral or tricuspid regurgitation, level present in either maxillary sinus right ventricle difficult to view but does (Figure 2,A) not appear substantially enlarged

FIGURE 2. Case 1. Point-of-care ultrasonographic images. A, Normal maxillary sinus (left) compared with abnormal, fluid-filled maxillary sinus (right). B, Pulmonary images showing normal lung (right) and abnormal lung with pulmonary edema(left).C,Viewatthelevelofthe right diaphragm with pleural effusion and dilated inferior vena cava (IVC). D, Parasternal long-axis view of the heart showing thickened left ventricular (LV) walls, left atrium (LA), and ascending aorta (Ao).

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d Abdomen: and spleen size causes of diffuse interstitial lung abnormalities normal, no ascites visible most likely. The differential diagnosis is further narrowed by focused cardiac ultrasonography to assess LV systolic function57,58,60,77 and an Differential Diagnosis. BasedonPOCUS IVC examination to estimate the central venous examination findings of a plethoric IVC, bilat- pressure.78 In the absence of cardiac findings eral B lines, pleural effusions, and severely suggestive of cardiogenic pulmonary edema, a reduced LV systolic function, the primary diag- focused work-up or empirical treatment of nosis in the differential is acute decompensated pneumonia would have ensued. systolic heart failure with pulmonary edema and The following workflow may be employed. elevated central venous pressure. Asthma exac- (1) The lack of B lines on pulmonary ultraso- erbation, allergic pneumonitis, pneumonia, nography rules out dyspnea from hydrostatic and pulmonary hypertension with obstructive cardiogenic pulmonary edema.26,54 (2) The sleep apnea are highly unlikely based on the lack of consolidation or B lines reduces the POCUS examination findings. likelihood of pneumonia considerably; in a patient with a low pretest probability of pneu- Plan With POCUS-Assisted Physical Exam- monia, the diagnosis can be ruled out (note ination. For patients with the aforementioned that although the sensitivity of POCUS for findings on POCUS-assisted physical exami- pneumonia is high in critically ill patients, nation, the following steps would be taken: central pneumonia can be missed, especially d Admit to hospital from clinic in less severe cases frequently seen in out- 19,26,34,66,70,71,74,79-81 d Comprehensive transthoracic echocardiog- patient presentations). raphy to evaluate LV function and pericar- (3) The differential diagnosis now includes dial effusion the next morning obstructive lung disease and pulmonary d Cardiac ischemic work-up that can be difficult to distin- d Intravenous diuresis guish with basic POCUS applica- tions.19,26,34,66,70,71,74,79-81 (4) at this point may be valuable if findings of Discussion obstructive lung disease, such as decreased The identification of elevated central venous breath sounds and wheezing, are present. pressure (IVC dilation with minimal (5) If findings of obstructive lung disease are collapse),38,49-53 pulmonary edema (bilateral not present, a combination of venous and interstitial syndrome B lines),54-56 and pleural focused cardiac ultrasonography can further effusions combined with an unanticipated narrow the differential diagnosis to improve reduction in LV systolic function25,41,57-64 efficiency of further work-up (Figure 3). dramatically changed this patient’s evaluation and management. During his inpatient work- CASE 2 up, isolated LV noncompaction was diagnosed A 69-year-old man with cirrhosis secondary to after cardiac magnetic resonance imaging and alcohol abuse, benign prostatic hypertrophy, coronary . type 2 diabetes mellitus, and nephrolithiasis Shortness of breath entails a broad differen- was admitted to the hospital with lethargy, tial, and the addition of POCUS in real time at , increased abdominal distention, the bedside can tremendously help mitigate and a subjective over the preceding 24 delay in appropriate testing and diag- hours. He reported minimal oral intake and nosis.26,33,34,65-74 The presence of B lines on a mild productive for the past 2 weeks. the initial pulmonary ultrasonography in this A syncopal episode while getting out of bed patient focuses the differential on heart failure, prompted transport to the emergency depart- pneumonia, interstitial lung disease, and poten- ment. Initial laboratory tests in the emergency tially .26,55,56,74-76 The department revealed acute renal failure (ARF), distribution of B lines is helpful in further nar- leukocytosis, thrombocytopenia, and elevated rowing the differential diagnosis.26 The presence troponin T level. revealed of bilateral diffuse B lines makes cardiogenic sinus with 1- to 2-mm lateral pulmonary edema, viral pneumonia, and other ST-segment .

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Shortness of breath

POCUS No Lung point visible Possible pneumothorax Lung slidinga

Ye s Ruled out: Ye s Ruled in: pneumothorax pneumothorax Ye s No Consolidation

Ye s Dynamic air bronchogramsb B linesa Ruled out: No pulmonary edema No Ye s b c Consider obstructive lung disease, Very likely pneumonia Pneumonia vs atelectasis pulmonary embolism, pulmonary hypertension, and other nonparenchymal etiologies History, laboratory Bilateral data, formal imaging Ye s History, traditional physical examination, cardiac Low likelihood: No ultrasonography, laboratory pulmonary edema data, formal imaging History, cardiac Pulmonary edema, pulmonary fibrosis, ultrasonography, diffuse interstitial process (viral Pneumonia, pneumonitis, History, laboratory data laboratory data pneumonia, ARDS, others) pulmonary embolism

FIGURE 3. Typical point-of-care ultrasonography (POCUS)eintegrated approach to a patient presenting with shortness of breath. ARDS ¼ acute respiratory distress syndrome; a ¼ Supplemental Video 1;b¼ Supplemental Video 6;c¼ Supplemental Video 2. Supplemental videos are available online at http://www.mayoclinicproceedings.org.

Traditional Physical Examination Differential Diagnosis. (1) Hypotension and Traditional physical examination revealed the tachycardia secondary to (a) sepsis due to spon- following: taneous bacterial peritonitis (SBP), pneumonia, or biliary process, (b) due to d Vital signs: Temperature, 37.7 C; pulse rate, alcoholic cardiomyopathy or ischemia, (c) 110 beats/min; blood pressure, 72/32 mm from or Hg; respiratory rate, 28 breaths/min; oxygen pulmonary embolism, or (d) hypovolemic saturation, 91%; body mass index, 18 kg/m2 shock from diuretics and reduced intake; and d Pulmonary: Decreased lung sounds bilater- (2) ARF secondary to (a) prerenal etiologies, ally at the bases, intermittent bibasilar including hypotension vs hepatorenal physi- crackles ology, or (b) postrenal etiologies, such as benign d Cardiovascular: Tachycardia, regular prostatic hypertrophy or nephrolithiasis. rhythm, no murmur, neck veins not visible, warm bilateral lower extremities with mild Plan With Traditional Physical Examination edema to the shin (right greater than left) Alone. For patients with the aforementioned d Abdomen: Protuberant abdomen with findings on traditional physical examination, bulging flanks and dullness to percussion, the following steps would be taken: moderate diffuse tenderness on palpation without acute peritoneal signs, liver and d Chest radiography to evaluate for possible spleen examination limited due to abdom- pulmonary infiltrate inal distention and , no costovertebral d Blood and urine cultures, urinalysis, and angle tenderness liver biochemical tests d Skin: No , dilated venous pattern d Abdominal ultrasonography to evaluate for on abdomen, palmar erythema, no possible obstructive biliary process and

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ascites, followed by diagnostic paracentesis be normal with no sonographic Murphy performed in the department sign d Central venous catheter (CVC) placement for central venous pressure monitoring, Differential Diagnosis. Based on the POCUS fluid resuscitation, and possible vasopressor findings of a collapsed IVC, hyperdynamic support LV, ascites, splenomegaly, and cirrhotic liver, d Initiation of empirical broad-spectrum anti- the differential diagnosis was narrowed to biotics to cover potential pulmonary and secondary to sepsis syndrome abdominal sources of sepsis due to SBP or possible biliary process and d Comprehensive transthoracic echocardiog- ARF due to a prerenal/renal etiology. raphy to evaluate LV function and pericar- dial effusion the next morning Plan With POCUS-Assisted Physical Exam- d Renal ultrasonography in the radiology ination. For patients with the aforementioned department to evaluate for findings on POCUS-assisted physical exami- d Bladder scan or empirical urinary catheter nation, the following steps would be taken: placement to measure postvoid residual urine volume d Bedside paracentesis with ultrasound guid- d Serial laboratory measurements of lactate ance to evaluate for SBP (Supplemental and troponin levels with fluid resuscitation Video 5) d Immediate volume resuscitation d Serial bedside POCUS of LV, IVC, and lungs POCUS-Assisted Physical Examination during fluid resuscitation to monitor for POCUS-assisted physical examination early signs of pulmonary edema with low revealed the following: threshold for transfer to critical care unit d Pulmonary: Bilateral lung sliding noted for vasopressor and fluid support throughout, bilateral elevated hemidia- d Empirical broad-spectrum antibiotics to phragm to tip of scapula with small bilateral cover possible SBP and biliary source of pleural effusions and few B lines in both sepsis dependent lung fields associated with mild d Blood and urine cultures, urinalysis, and bilateral atelectasis liver biochemical tests d Cardiovascular: Focused cardiac ultrasonogra- d Consider right upper quadrant ultrasonog- phy revealed trace pericardial effusion, normal raphy for possible obstructive biliary process right ventricle size with increased contractility, d Serial laboratory testing including lactate hyperdynamic LV with “kissing” endocardium and troponin levels with fluid (Supplemental Video 3, available online at resuscitation http://www.mayoclinicproceedings.org), IVC d Comprehensive transthoracic echocardio- less than 1 cm in diameter with 100% collapse graphy to evaluate LV function and pericar- except during expiration (Supplemental dial effusion the next morning Video 4, available online at http://www. mayoclinicproceedings.org). Lower extremity vascular assessment revealed complete Discussion compression of saphenous veins, common/ Bedside ultrasound-guided paracentesis has deep/superficial femoral veins, and popliteal been reported to be safe and effective when veins bilaterally performed by nonradiologists82-84 and can d Abdomen: Moderate ascites throughout quickly identify the source of sepsis. Volume (Figure 4,A;Supplemental Video 5, resuscitation guided by POCUS includes available online at http://www.mayoclinic discontinuation of intravenous fluids when proceedings.org), small liver (8-cm midcla- the POCUS examination reveals early signs vicular span) with scalloped cortex, enlarged of pulmonary edema74,85 or when minimal spleen (19 cm in long axis and 8 cm in short change in volume occurs with a passive axis) (Figure 4, B), minimally distended leg raise.86-91 This patient was transitioned to bladder (Figure 4, C), and no hydronephro- the intensive care unit for initiation of early sis (Figure 4, D). Gallbladder was noted to vasopressor support. The ARF normalized

Mayo Clin Proc. n December 2016;91(12):1811-1827 n http://dx.doi.org/10.1016/j.mayocp.2016.08.023 1819 www.mayoclinicproceedings.org MAYO CLINIC PROCEEDINGS

FIGURE 4. Case 2. Point-of-care ultrasonographic images. A, Cirrhotic liver with surrounding ascites. B, Enlarged spleen measuring 18.58.2 cm compared with a normal sized spleen (inset). C, Minimally distended bladder in transverse plane with approximately 75 mL of urine. D, Normal without hydronephrosis compared with kidney with moderate hydronephrosis (inset).

over the next 48 hours with fluid resuscitation information on hemodynamics to assess renal and vasopressor support. perfusion.100-103 Hypotension has a broad differential diag- nosis, as in this case, and poses a diagnostic CHALLENGES AND PITFALLS and therapeutic challenge to internists. Despite the several undisputed advantages of POCUS of the heart, lungs, abdomen, and pe- utilizing POCUS, there are several barriers ripheral vascular system can expedite evalua- and pitfalls to consider. First, there are chal- tion for potential etiologies of hypovolemic, lenges relating to equipment and technology. distributive, cardiogenic, or obstructive POCUS can be performed with a variety of shock.29,66,92-97 Serial POCUS can be used to available equipment: full-sized traditional ma- monitor ongoing fluid resuscitation and help chines, laptop-sized devices, and pocket-sized determine the need for vasopressor devices. Even ultrasound transducers that can support.85,98 be plugged directly into handheld computers Acute renal failure is common in the inpa- are now available. Although many physicians tient setting and often creates a diagnostic generally prefer compact ultrasonography de- dilemma. A POCUS examination of the kid- vices for portability, these devices have limited neys has been found to rapidly and effectively ability to adjust image quality. Concerns have rule out hydronephrosis and guide the need been raised about small handheld systems for urinary catheterization.99 POCUS of the with regard to their narrow sector, smaller lungs and cardiovascular system supplements field of view, lower resolution, and simplified the renal examination by providing transducer technology.25,104,105 Although

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studies have documented that small ultraso- policies and procedures for quality assurance nography devices can be used to answer and billing. Emergency medicine societies focused questions,18,61,106-115 operators must have addressed these issues and assisted be aware of their limitations. physicians in understanding correct and From an operator and training perspective, compliant coding for the past 2 de- studies have found that the utility of a POCUS cades.37,39,40 In terms of billing, POCUS can examination depends on the experience and potentially influence the evaluation and man- skills of the operator.42,48,116-120 Operator agement code by affecting the complexity of training is crucial for POCUS to be utilized medical decision making (Current Procedural correctly in patient care, and studies have Terminology).112-115 Some believe that reim- revealed that barriers to POCUS adoption bursement is essential to cover the substantial include insufficient faculty training, high cost cost of POCUS education and equipment pur- of ultrasonography machines, and time chasing and maintenance.112-115 Conversely, required to train physicians.45,121 The relatively others view POCUS as an extension of the high level of operator dependency compared physical examination, which raises concerns with other diagnostic testing is reasonably ex- that a heavy focus on billing may block the pected, given the multiple skills required to routine use of POCUS.116-118 Future reim- perform a POCUS examination. First, a POCUS bursement systems that capture an “episode examination begins with formulation of a spe- of care,” also known as “bundling,” will likely cific clinical question and a decision to utilize change the perspectives on POCUS billing, POCUS to answer this question.122 Next, acqui- documentation, and image archiving.112,117 sition of images requires knowledge of sono- As the workflow for POCUS in internal medi- graphic windows, ultrasound physics, and cine matures, medical practices will be hand-eye-brain coordination to manipulate required to provide the administrative infra- the transducer to optimize image quality.122 structure needed to meet these evolving stan- Interpretation of POCUS images requires skills dards of care for use of POCUS.25,104,116 that are independent from physical examination For effective integration of POCUS into clin- skills, and operators must recognize artifacts ical care, quality assurance is an important that are encountered during image acquisition consideration. Although quality assurance has and interpretation.122 Most importantly, been emphasized to avoid misinterpretation of POCUS findings must be interpreted and inte- images, most malpractice cases related to grated with other clinical data to effectively POCUS in emergency medicine have been due guide clinical decision making.122 Failure to failure to perform a POCUS examination in during any step of this multistep process may a timely manner, rather than misinterpretation undermine the true value of using POCUS. or misdiagnosis with the use of POCUS.76 The The skills needed to perform POCUS ex- extent to which quality assurance will be needed aminations have not been uniformly taught in internal medicine and other specialties is yet in undergraduate or graduate medical educa- to be determined because increased legal risks tion. Although a movement to integrate may occur with either failure to use POCUS or POCUS education into medical schools or misinterpretation of POCUS images. internal medicine residency programs has been gaining momentum over the past FUTURE RESEARCH decade,43,121,123-129 there is no consensus on Early POCUS research focused on diagnostic the training required to reach adequate accuracy to establish that health care profes- POCUS competency levels in general internal sionals with focused training in ultrasonogra- medicine.25,104,110,111,130-133 It is generally phy can acquire and interpret images agreed that training must include basic knowl- accurately. The diagnostic accuracy of front- edge of ultrasound physics and supervised line physicians performing POCUS examina- image acquisition and interpretation prac- tions has been compared with imaging tice.25,104,110,111,130-133 acquired by full-time sonographers and inter- Other potential challenges include the preted by imaging specialists, primarily radiol- availability of templates for documentation, ogists or cardiologists. Several published electronic storage for image archiving, and studies have proven that POCUS has

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diagnostic accuracy similar to that of criterion professionals, ranging from medical students standard imaging studies for specific findings, to senior attending physicians, to utilize such as pneumothorax,67,119 pericardial effu- POCUS? Experts generally agree that the use sion,42,120 or lower extremity deep venous of POCUS requires basic knowledge of ultraso- thrombosis.48 However, few studies have nography, image acquisition and interpretation compared the diagnostic accuracy of POCUS skills, and an understanding of integration of vs the traditional diagnostic approach using POCUS findings into clinical decision making. history and physical examination. Interest- If we believe that the focus should be outcomes ingly, these studies have clearly confirmed research rather than training, then we are rele- the superiority of POCUS. For instance, half gated to performing studies with a few experts as many major cardiac findings were missed performing all POCUS examinations, which when a cardiac physical examination per- may be biased toward benefit because the formed by experienced cardiologists was experts’ skill level is beyond what may be supplemented with a focused cardiac ultraso- achievable by a physician with average POCUS nographic examination.121 Although a fairer skills. On the contrary, if we believe training comparison may be to compare the diagnostic should be the focus, then medical institutions, accuracy of POCUS to that of physical exami- including medical schools, hospitals, and nation, rather than criterion standard imaging health care systems, will have to invest in studies, few comparative studies of internist- training physicians in basic POCUS applica- performed physical examinations, with or tions before large effectiveness trials can be without the addition of POCUS, have been undertaken to evaluate the impact of POCUS published.45 on clinical outcomes. As this debate has During the past 15 years, POCUS research continued, medical schools have begun to has shifted focus from diagnostic accuracy to invest heavily in integrating POCUS training demonstration of improved health outcomes. into clinical skills education, and positive stu- Use of POCUS to guide bedside procedures dent reviews and publicity continue to drive has been reported to reduce procedure- this integration in medical school curricula. related complications, including arterial punc- Meanwhile, practicing internists are feeling tures during central venous catheterization,134 growing pressures to acquire basic POCUS postthoracentsis pneumothorax, and postpar- skills because their trainees may have more acentesis bleeding complications, along with advanced POCUS skills than they do. the costs and lengths of stay associated with From a health care system perspective, the these complications.123,124 However, few ran- field of POCUS is ripe for health services domized trials have been published, and a research because an increasing number of paucity of data exists supporting the routine POCUS applications are recommended by use of POCUS for diagnostic evalua- evidence-based guidelines. For example, tions.15,69,77,125-127 Only one randomized trial consider the use of ultrasound guidance to with internal medicineetrained physicians has place CVCs. Since the early 2000s, ultrasound been published comparing routine focused guidance for placement of CVCs has been cardiac ultrasonography vs standard care in recommended by national patient safety hospitalized general medicine patients. This and quality organizations on the basis of several study found a potential reduction in length randomized trials and meta-analyses128,129,135; of stay with the use of POCUS in the cohort however, the use of ultrasound guidance to of patients with heart failure.43 Thus, compar- insert CVCs has not been universally adopted ative studies evaluating the clinical and health in clinical practice. Investigations using services outcomes of usual care with and methods from implementation science may without the routine use of POCUS by inter- reveal barriers to adoption of POCUS use for nists for different conditions are needed. CVC insertion. Lessons learned from studying Another interesting facet of POCUS this implementation gap may guide future research is whether the higher-priority focus implementation of POCUS use within the prac- is physician training or clinical outcomes. A tice of internal medicine. fundamental question has yet to be answered: Certain POCUS applications with well- How do we effectively train health care proven benefits, such as use of ultrasound

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