Point-of-care ultrasound in Acute Medicine

Summary

This thesis describes studies about point-of-care ultrasound (POCUS) in acute medicine focusing on four aspects: 1) the current role of POCUS in dyspnea, nontraumatic hypotension, and shock; 2) the novel role of POCUS as a screening instrument for possible COVID-19 pneumonia; 3) the novel role of POCUS in risk stratifying confirmed COVID-19 pneumonia; 4) the evaluation of a basic POCUS training of residents in internal medicine on knowledge gain and practical performance. The aim of this work is to advance the understanding of POCUS use in acute care, which may help direct future studies on patient management and training of medical students and physicians. In the general introduction and outline of this thesis (Chapter 1), an overview on POCUS in acute medicine is given. The application of ultrasound conducted by the treating physician at the patient’s bedside, coined POCUS, can better distinguish physiological from pathophysiological findings compared to the standard physical examination. As such, POCUS can efficiently augment diagnostic accuracy, exclude certain specific diagnoses, and help to narrow the differential diagnoses. POCUS equipment has evolved rapidly over the past decade. A transducer connected to a smart phone has become available thereby reducing barriers to its use outside the hospital or in less affluent countries. Also, there are great expectations about artificial intelligence which can aid the treating physician in correct probe placement, image interpretation, and performing advanced measurements. A growing number of medical societies and medical schools has decided to make basic POCUS mandatory in their curricula. Opponents to this decision state that the value of POCUS on an increased diagnostic accuracy has been proven only in studies conducted by POCUS experts, while in day-to-day practice physicians with basic POCUS expertise conduct and interpret the scans. Chapter 2 describes a systematic review of 89 original studies on POCUS and dyspnea, nontraumatic hypotension, and shock. POCUS in the initial workup increases the diagnostic accuracy in patients with dyspnea, nontraumatic hypotension and shock in the emergency department, intensive care unit, and medical ward setting. POCUS is capable of narrowing the differential diagnoses and is faster, and more feasible in the acute setting than other diagnostics available. Study results on outcome measures are scarce and heterogenous. The quality of the included studies is considered low most of the times, mainly because of performance and selection bias and absence of a gold standard as the reference test. A multicentre, prospective, observational study to compare the diagnostic accuracy of POCUS of the lungs and computed tomography of the chest (chest CT) in adult patients with suspected COVID-19 is described in Chapter 3. 187 adult patients with suspected COVID-19 referred to internal medicine in the emergency department are included in this study. POCUS of the lungs and chest CT have comparable diagnostic accuracy for COVID-19 pneumonia. POCUS of the lungs can safely exclude clinically relevant COVID-19 pneumonia. POCUS of the lungs has the advantage that it can be used in patients without the need to transport them. This potentially prevents nosocomial spread of infection. In addition, because of the bedside nature of POCUS it can reduce time to diagnosis and treatment. Chapter 4 describes a multicentre, prospective, observational study that compares the diagnostic accuracy of three commonly used protocols on point-of-care ultrasound of the lungs in identifying COVID-19 pneumonia. 202 adult patients with suspected COVID-19 are included in whom a comprehensive 12-zone POCUS of the lungs is conducted. This study demonstrates that identifying COVID-19 pneumonia in the emergency department can be aided by POCUS of the lungs. As a screening tool, the efficient 6-zone protocol, in the literature known as the Bedside Lung Ultrasound in Emergency (BLUE) protocol is excellent. The comprehensive 12-zone protocol, however, is more specific and gives a general impression on lung involvement. In Chapter 5, a multicentre, prospective, observational study is described that assesses the utility of point-of-care ultrasound of the lungs for characterizing lung involvement and, thereby, clinical risk determination in COVID-19 pneumonia. 114 adult patients with COVID19 pneumonia in the emergency department are included. Disease severity of the lungs is determined using the lung ultrasound score (LUS) and chest CT severity score. The associations between disease severity and poor outcome, and length of hospital stay are assessed. Also the ability of the lung ultrasound score to differentiate between disease severity groups is assessed. This study demonstrates that disease severity, determined by the LUS, is associated with poor outcomes, and an increase in length of hospital stay. The LUS is able to stratify patients into disease severity groups and the LUS correlates well with chest CT severity score. POCUS may aid the risk stratification and triage of patients with COVID-19 in the emergency department. Chapter 6 describes a small prospective, observational study that evaluates a basic point-ofcare ultrasound course for residents in internal medicine. 48 residents without relevant ultrasound experience have attended a total of 6 courses. 39 participants are assessed on theoretical and practical skills and they have all obtained sufficient results on knowledge and practice of point-of-care ultrasound. Only 30 subjects are assessed after a follow up time of 3 months and they demonstrate retention of practical ultrasound skills. We emphasize that it is absolutely necessary to have staff members who are experts in POCUS to ensure that residents are given the chance to increase their basic POCUS skills and become truly POCUS proficient. 7 Summary | 141 This thesis describes studies about point-of-care ultrasound (POCUS) in acute medicine focusing on four aspects: 1) the current role of POCUS in dyspnea, nontraumatic hypotension, and shock; 2) the novel role of POCUS as a screening instrument for possible COVID-19 pneumonia; 3) the novel role of POCUS in risk stratifying confirmed COVID-19 pneumonia; 4) the evaluation of a basic POCUS training of residents in internal medicine on knowledge gain and practical performance. The aim of this work is to advance the understanding of POCUS use in acute care, which may help direct future studies on patient management and training of medical students and physicians. In the general introduction and outline of this thesis (Chapter 1), an overview on POCUS in acute medicine is given. The application of ultrasound conducted by the treating physician at the patient’s bedside, coined POCUS, can better distinguish physiological from pathophysiological findings compared to the standard physical examination. As such, POCUS can efficiently augment diagnostic accuracy, exclude certain specific diagnoses, and help to narrow the differential diagnoses. POCUS equipment has evolved rapidly over the past decade. A transducer connected to a smart phone has become available thereby reducing barriers to its use outside the hospital or in less affluent countries. Also, there are great expectations about artificial intelligence which can aid the treating physician in correct probe placement, image interpretation, and performing advanced measurements. A growing number of medical societies and medical schools has decided to make basic POCUS mandatory in their curricula. Opponents to this decision state that the value of POCUS on an increased diagnostic accuracy has been proven only in studies conducted by POCUS experts, while in day-to-day practice physicians with basic POCUS expertise conduct and interpret the scans. Chapter 2 describes a systematic review of 89 original studies on POCUS and dyspnea, nontraumatic hypotension, and shock. POCUS in the initial workup increases the diagnostic accuracy in patients with dyspnea, nontraumatic hypotension and shock in the emergency department, intensive care unit, and medical ward setting. POCUS is capable of narrowing the differential diagnoses and is faster, and more feasible in the acute setting than other diagnostics available. Study results on outcome measures are scarce and heterogenous. The quality of the included studies is considered low most of the times, mainly because of performance and selection bias and absence of a gold standard as the reference test. A multicentre, prospective, observational study to compare the diagnostic accuracy of POCUS of the lungs and computed tomography of the chest (chest CT) in adult patients with suspected COVID-19 is described in Chapter 3. 187 adult patients with suspected COVID-19 referred to internal medicine in the emergency department are included in this study. POCUS of the lungs and chest CT have comparable diagnostic accuracy for COVID-19 pneumonia. POCUS of the lungs can safely exclude clinically relevant COVID-19 pneumonia. POCUS of the lungs has the advantage that it can be used in patients without the need to transport them. This potentially prevents nosocomial spread of infection. In addition, because of the bedside nature of POCUS it can reduce time to diagnosis and treatment. Chapter 4 describes a multicentre, prospective, observational study that compares the diagnostic accuracy of three commonly used protocols on point-of-care ultrasound of the lungs in identifying COVID-19 pneumonia. 202 adult patients with suspected COVID-19 are included in whom a comprehensive 12-zone POCUS of the lungs is conducted. This study demonstrates that identifying COVID-19 pneumonia in the emergency department can be aided by POCUS of the lungs. As a screening tool, the efficient 6-zone protocol, in the literature known as the Bedside Lung Ultrasound in Emergency (BLUE) protocol is excellent. The comprehensive 12-zone protocol, however, is more specific and gives a general impression on lung involvement. In Chapter 5, a multicentre, prospective, observational study is described that assesses the utility of point-of-care ultrasound of the lungs for characterizing lung involvement and, thereby, clinical risk determination in COVID-19 pneumonia. 114 adult patients with COVID19 pneumonia in the emergency department are included. Disease severity of the lungs is determined using the lung ultrasound score (LUS) and chest CT severity score. The associations between disease severity and poor outcome, and length of hospital stay are assessed. Also the ability of the lung ultrasound score to differentiate between disease severity groups is assessed. This study demonstrates that disease severity, determined by the LUS, is associated with poor outcomes, and an increase in length of hospital stay. The LUS is able to stratify patients into disease severity groups and the LUS correlates well with chest CT severity score. POCUS may aid the risk stratification and triage of patients with COVID-19 in the emergency department. Chapter 6 describes a small prospective, observational study that evaluates a basic point-ofcare ultrasound course for residents in internal medicine. 48 residents without relevant ultrasound experience have attended a total of 6 courses. 39 participants are assessed on theoretical and practical skills and they have all obtained sufficient results on knowledge and practice of point-of-care ultrasound. Only 30 subjects are assessed after a follow up time of 3 months and they demonstrate retention of practical ultrasound skills. We emphasize that it is absolutely necessary to have staff members who are experts in POCUS to ensure that residents are given the chance to increase their basic POCUS skills and become truly POCUS proficient.