Ultrasound: Part 2, An Issue of Critical Care Clinics, E-Book (eBook)

Ultrasound: Part 2, An Issue of Critical Care Clinics, E-Book

Theresa S. Wu (Autor)

eBook Download: PDF | EPUB

2014 | 1. Auflage
169 Seiten
Elsevier Health Sciences (Verlag)
978-0-323-28994-8 (ISBN)

Infos

The second part of Dr. Wu's Ultrasound edition has more topics covered by an expert panel of authors. Topics discussed include ocular ultrasound, basic procedures, musculoskeletal, deep vein thrombosis, advanced procedures, and OB/GYN!

Inhalt

Front Cover 1
Ultrasound: Part 2 2
copyright 
3 
Contributors 4
Consulting Editor 4
Editor 4
Authors 4
Contents 6
Critical Care Clinics 
8 
Diagnostic Ultrasonography for Peripheral Vascular Emergencies 10
Key points 10
Introduction 10
Technical considerations of peripheral vascular sonography 11
Transducer Selection 11
Color Doppler Ultrasonography 11
Pulsed-Wave Doppler Ultrasonography 12
Comparison of Arterial and Venous Ultrasound Findings 13
Deep vein thrombosis 14
Wells Criteria 14
D-Dimer 15
DVT Evaluation Algorithm 15
Ultrasonography Findings of DVT 15
Anatomy and Related Sonographic Findings for DVT 16
Peripheral Artery Aneurysms 19
Pseudoaneurysms 24
Arterial Occlusion of Extremities 25
Summary 30
References 30
Bedside Ultrasonography for Obstetric and Gynecologic Emergencies 32
Key points 32
Introduction 32
Technical considerations of obstetric and gynecologic sonography 33
Transducer Selection 33
Technique for performing transabdominal pelvic ultrasonography 33
Technique for performing endocavitary pelvic ultrasonography 35
Emergency ultrasonography in the obstetric patient 36
Detecting a normal IUP 37
Correlation with serum ß-human chorionic gonadotropin levels 39
Fetal dating and viability by trimester 39
Ectopic pregnancy 41
Heterotopic pregnancy 43
Gestational trophoblastic disease 44
Emergency ultrasonography in the gynecologic patient 45
Ovarian cysts 45
Ovarian torsion 46
TOA, hydrosalpinx, and pyosalpinx 46
Uterine leiomyomas 47
IUD assessment 48
Summary 49
References 49
Bedside Ocular Ultrasound 52
Key points 52
Introduction 52
Eye and orbit anatomy 52
Sclera and Cornea 53
Choroid, Ciliary Body, and Iris 53
Retina 54
Refractory Media 55
Optic Nerve and Ophthalmic Vessels 55
Ocular ultrasound examination technique 56
Patient Positioning 56
Technique 56
Emergent ocular abnormalities 58
Retinal Detachment 58
Vitreous Hemorrhage 58
Lens Dislocation 59
Globe Rupture 60
Optic Nerve Evaluation 62
Retrobulbar Hematoma 62
Intraocular Foreign Bodies 62
Periorbital Abscess 64
Summary 65
References 65
Bedside Musculoskeletal Ultrasonography 68
Key points 68
Introduction 68
Probe selection 70
Maximizing image quality 72
Normal structures 73
Skin 73
Subcutaneous Fat 75
Muscle 75
Lymph Nodes 75
Bone 76
Joints 76
Tendons 76
Artifacts 78
Sonographic appearances of musculoskeletal pathology 79
Cellulitis 79
Phlegmon 81
Abscess 81
Lymphadenitis 82
Myositis 82
Soft Tissue Hematoma 85
Soft Tissue Foreign Bodies 86
Muscle Injuries 87
Joint Effusions 88
Popliteal Cysts 88
Fractures 90
Periostitis 91
Osteomyelitis 91
Tendon Injuries 91
Joint Prostheses 93
Sebaceous Cysts 93
Pilonidal Cysts 96
Lipomas 96
Summary 96
References 96
Basic Ultrasound-guided Procedures 100
Key points 100
Introduction 100
Ultrasound-guided Procedures: Axis and Orientation 100
Ultrasound-guided Versus Ultrasound-assisted Procedures 101
Ultrasound-guided Procedures: Visualizing the Needle 101
Ultrasound-guided peripheral intravenous placement 102
Clinical Indications 102
Anatomy 103
Technique 103
Tips 104
Ultrasound-guided central venous access 104
Clinical Indications 104
Anatomy 105
IJ vein 105
Femoral vein 106
Subclavian vein 106
Technique 106
Tips 108
Ultrasound-guided arterial access 109
Clinical Indications 109
Anatomy: Radial Artery 109
Anatomy: Femoral Artery 110
Anatomy: Brachial Artery 111
Anatomy: Dorsalis Pedis Artery 111
Technique 111
Tips 112
Ultrasound-guided suprapubic aspiration 112
Clinical Indications 112
Anatomy 112
Technique 112
Tips 113
Ultrasound-guided abscess localization for incision and drainage 113
Clinical Indications 113
Technique 114
Tips 115
Ultrasound-guided foreign body localization 116
Clinical Indications 116
Technique 117
Tips 117
Ultrasound-guided arthrocentesis 118
Clinical Indications 118
Anatomy 119
Knee 119
Hip 119
Ankle 120
Shoulder: anterior approach 121
Shoulder: posterior approach 122
Elbow 123
Technique for an Ultrasound-guided Arthrocentesis 124
Tips 125
Summary 127
References 127
Advanced Ultrasound Procedures 130
Key points 130
Ultrasound-guided pericardiocentesis 130
Background 130
Diagnosis 131
Precautions 131
Procedure 132
Pearls and Pitfalls 133
Ultrasound-guided thoracentesis 135
Background 135
Diagnosis 135
Precautions 135
Procedure 136
Pearls and Pitfalls 137
Ultrasound-guided paracentesis 138
Background 138
Diagnosis 138
Precautions 139
Procedure 139
Pearls and Pitfalls 140
Ultrasound-guided lumbar puncture 141
Background 141
Diagnosis 142
Precautions 142
Procedure 142
Pearls and Pitfalls 144
Ultrasound-guided nerve blocks 145
Background 145
Precautions 146
Procedure 146
Femoral Nerve Block 147
Pearls and Pitfalls 149
Ultrasound-guided peritonsillar abscess drainage 149
Background 149
Diagnosis 150
Precautions 150
Procedure 150
Pearls and Pitfalls 151
Summary 152
References 152
Index 156

Textauszug

Diagnostic Ultrasonography for Peripheral Vascular Emergencies

Thomas Cook, MD, Laura Nolting, MD∗, Caleb Barr, MD and Patrick Hunt, MD,     Department of Emergency Medicine, Palmetto Health Richland, 14 Medical Park, Suite 350, Columbia, SC 29203, USA

∗Corresponding author. Email: [e-mail]

Over the past decade, emergency and critical care physicians have been empowered with the ability to use bedside ultrasonography to assist in the evaluation and management of a variety of emergent conditions. Today a single health care provider at the bedside with Duplex ultrasound technology can evaluate peripheral vascular calamities that once required significant time and a variety of health care personnel for the diagnosis. This article highlights peripheral thromboembolic disease, aneurysm, pseudoaneurysm, and arterial occlusion in the acute care setting.

Keywords

Ultrasonography

Deep vein thrombosis

Arterial occlusion

Pseudoaneurysm

Aneurysm

Key points

• This article discusses how to differentiate the arterial from the venous system by ultrasonography, using real-time scanning, color Doppler, and pulsed-wave Doppler.

• This article describes the approach to detecting deep vein thrombosis in the acute care setting.

• Peripheral arterial aneurysm can present clinically as an asymptomatic pulsatile mass or acute limb-threatening ischemia. This article discusses the detection of peripheral aneurysms using ultrasonography.

• Pseudoaneurysms, while rare, do occur in the acute care setting. This article describes the ultrasonographic findings of pseudoaneurysm, and detection by ultrasonography of acute arterial occlusion.

Introduction

Regardless of whether an extremity is swollen, painful, tender, cool, pulseless, or possesses an enlarged mass, it is often caused by vascular abnormality. The bedside evaluation of peripheral vascular emergencies now relies on diagnostic ultrasonography more than any other laboratory or imaging modality. Having the skills to perform ultrasonography at the bedside not only expedites the care of seriously ill patients but also provides the clinician-sonographer the ability to examine other areas of the body that might be affected by acute disease of the peripheral vasculature.

This article provides information needed for the use of ultrasonography in the diagnosis of emergent pathology of the peripheral vasculature. It covers the sonographic evaluation of deep vein thrombosis (DVT) and the peripheral arterial emergencies of aneurysm, pseudoaneurysm, and obstruction. Techniques and anatomy related to performing and interpreting these ultrasonography studies are emphasized. Aortic aneurysms and ultrasound-guided vascular access are discussed in another article elsewhere in this issue.

Technical considerations of peripheral vascular sonography

Transducer Selection

Because peripheral vascular structures are relatively small and superficial, high-resolution ultrasound transducers are required. Linear-array, high-frequency transducers provide the best 2-dimensional image resolution, and are therefore preferred for these sonographic examinations (Fig. 1).

Fig. 1 Linear-array transducer with image of upper extremity vasculature.

Color Doppler Ultrasonography

Even relatively inexpensive systems now have Doppler ultrasound capability. Color Doppler ultrasound technology uses the change in frequencies caused by blood flow to create corresponding images on the viewing screen. If the blood flow is moving toward the transducer, the return echo will have a higher frequency than was originally generated by the ultrasound system. When this occurs the ultrasound system will, by default, create a red image on the screen that represents the moving blood. If the blood flow is moving away from the transducer, the return echo will have a lower frequency than was originally generated by the ultrasound system. When this occurs, the ultrasound system will create a blue image on the screen (Fig. 2). With all Doppler imaging, the brighter the color, the faster the blood is moving. Color Doppler imaging only occurs within a relatively small area of the viewing screen referred to as the region of interest.

Fig. 2 Blood flow toward the transducer is red. Blood flow away from the transducer is blue. Doppler images are only seen within the rectangular box on the viewing screen. This area is referred to as the region of interest.

It is imperative for the clinician-sonographer to be correctly oriented to the vasculature. Typically the transducer should be oriented so that arterial flow is moving toward the probe and venous flow is moving away. If this is done, arterial blood flow will appear red and venous blood flow will appear blue. If the transducer is oriented so that the venous flow is moving toward the transducer, the color of arterial and venous blood will be reversed.

In addition, the ultrasound signal should be directed as close to parallel as possible to the flow of blood. When the ultrasound signal is perpendicular to the flow of blood, the ultrasound system cannot give accurate information regarding the direction and velocity of the moving blood (Fig. 3).

Fig. 3 To obtain accurate data using Doppler ultrasonography, the examiner needs to orient the ultrasound signal as close to parallel as possible to the flow of blood (top). If the ultrasound signal is perpendicular to the blood flow (bottom), Doppler ultrasonography cannot be used accurately.

Pulsed-Wave Doppler Ultrasonography

Pulsed-wave Doppler (PWD) systems are able to provide Doppler shift data from a small segment along the ultrasound beam referred to as the sample volume or sample gate. The machine operator controls the location of this segment (Fig. 4).

Fig. 4 With pulsed-wave Doppler (PWD) the examiner places a sample volume to measure the flow characteristics of blood.

PWD converts the measured change in frequencies caused by blood flow within the sample volume into audible sounds or visual data graphed over time. With the audible sounds, higher-pitched sounds are the result of higher Doppler shifts, and thus indicate higher flow rates. Lower-pitched sounds are from lower Doppler shifts caused by lower flow rates. Interpretation of these sounds is more subjective, but the difference in flow rates is fairly easy to distinguish.

When PWD converts blood-flow data into a visual display, the characteristics of the blood flowing at the sample volume are graphed over time (Fig. 5). A baseline indicating no flow is seen on the viewing screen. If blood is flowing toward the transducer, a waveform will be seen above a baseline. If the blood is flowing away from the transducer, a waveform will be seen below the baseline.

Fig. 5 PWD takes flow data through the sample volume at the B-mode image and graphs it over time at the bottom. The waveform on the left indicates that blood is flowing toward the transducer. The waveform on the right indicates that blood is flowing away from the transducer.

Comparison of Arterial and Venous Ultrasound Findings

With 2-dimensional ultrasonography, arteries will be pulsatile and have thicker walls than veins; however, it is often difficult to see these differences when examining smaller vessels. Fortunately, there are 4 techniques that can be used to differentiate peripheral arteries from veins (Box 1).

Box 1   Techniques for differentiating vessels

Compression

Doppler color flow

Pulsed-wave Doppler

Distal augmentation

Compression is the most commonly used technique. Veins are much more compliant then arteries and normally can be completely compressed with light pressure, whereas arteries remain patent until a greater amount of pressure is applied.

Doppler color flow can be used to demonstrate the direction of blood flow and the presence or absence of arterial pulsations. Color flow can also be used to determine whether a given structure is nonvascular. Examples of this include lymph nodes, abscesses, cysts (ie, Baker cyst at the popliteal fossa), seromas, and hematomas.

PWD can differentiate arteries from veins by examination of the waveform created by the flow of blood at the sample volume. Arterial blood flow is pulsatile, whereas normal venous flow is continuous without evidence of pulsations (Fig. 6).

Fig. 6 PWD demonstrating arterial flow moving toward the transducer (top), and venous blood flow moving away from the transducer...

Produkt-Details

• Erscheint lt. Verlag: 1.6.2014
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Gesundheitsfachberufe
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Intensivmedizin
• Themenwelt: Medizinische Fachgebiete ► Radiologie / Bildgebende Verfahren ► Sonographie / Echokardiographie
• Themenwelt: Medizin / Pharmazie ► Pflege
• ISBN-10: 0-323-28994-0 / 0323289940
• ISBN-13: 978-0-323-28994-8 / 9780323289948