Emergency and Point of Care Ultrasound: Can One Modality Do It All?
Michael Blaivas, MD
Professor of Emergency Medicine
Associate Professor of Internal Medicine
President, WINFOCUS
Editor‐in‐Chief, Critical Ultrasound Journal
Chair, AIUM Emergency and Critical Care US Section
Northside Hospital Forsyth, Atlanta Georgia
Objectives
• Discuss ultrasound utility in near zero gravity conditions
• Discuss specific applications and why they may be useful
• Discuss current literature supporting use
Ultrasound
• Ideal modality for the space (volume), time and resource poor
• This includes most emergency departments, all austere and pre‐
hospital environments
Ultrasound
• Long list of applications utilized
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Cardiac
Abdominal
Pelvic
Procedures
Musculoskeletal
Ocular
Lung
Others…
Ultrasound
• Used in multiple roles including
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Diagnostic
Therapeutic
Procedure Guidance
Screening
• We will focus on three particularly well suited applications
Ocular Ultrasound
• Utilized for years in ophthalmology practice for year
• EM for about ten year
• Very helpful in multiple cases
– Foreign body
– Retinal detachment
– Vitreous hemorrhage
Ocular Ultrasound
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Floaters
Retro‐orbital hematoma
Globe injury
ICP (Intracranial Pressure)
Ocular US Basics
• Traditionally uses specialized equipment and in specialized settings
• The Ophthalmology office
• Radically different from ED, pre‐hospital settings or the space station
Ocular US Basics
• In the clinical setting we scan through a closed lid
• For patient comfort and because frequently evaluating trauma patients
• Transducer utilized is a multipurpose rather than single purpose one
Ocular US Basics
• In the clinical setting we scan through a closed lid
• For patient comfort and because frequently evaluating trauma patients
• Transducer utilized is a multipurpose rather than single purpose one
Ocular US Basics
• Due to attachment of ONS to eye the ONSD is measured 3 mm posterior to the globe
ONSD Measurement on US
• Clear and crisp image of ONS is critical
• Variability in measurement creates controversy
• However, most studies show good reproducibility
ONSD Measurement on US
• Novices will frequently have difficulty defining ONSD
• Better equipment yields better images
ONSD Measurement on US
• Novices will frequently have difficulty defining ONSD
• Better equipment yields better images
Ocular Ultrasound
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Floaters
Retro‐orbital hematoma
Globe injury
ICP (Intracranial Pressure)
• How does it help with establishing ICP (Elevated ICP)?
ICP and Ocular Ultrasound
• There is a constant communication between the subarachnoid space of the optic nerve sheath and the intracranial cavity – Hayreh SS. Pathogenesis of edema of the optic disc. Die Ophthalmol. 1968; 24:289‐411.
Optic Never Sheath Background
• Hayreh documented variability of the ONSD under changing CSF pressures by
• Placed rubber balloons into the subarachnoid space of monkeys
• Inflating the balloon caused a dilation of the optic nerve sheath, which resolved once the balloon was deflated
Optic Never Sheath Background
• Hansen and Helmke performed ocular US on patients receiving routine LP while draining fluid
• Patients were being treated for Pseudotumor cerebri (idiopathic intracranial hypertension)
• Authors removed and then infused fluid and documented change in OPND in relationship to ICP
Optic Never Sheath Background
• Researchers confirmed a relatively linear relationship from 4.7 mm at normal to over 7 mm where OPND diameter reached plateau
– Hansen HC, Helmke K. Validation of the optic nerve sheath response to changing cerebrospinal fluid pressure: ultrasound findings during intrathecal infusion tests. J Neurosurg. 1997; 87:34–40.
Ultrasound and Elevated ICP
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Most frequently described and studied is measurement of optic nerve sheath diameter (ONSD)
Studied in adults, children and infants
Cases, series and small prospective studies
ED, trauma and controlled settings
Trans‐cranial Doppler and EICP
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Blood flow correlates with EICP
Typically performed for brain death evaluation
Now studied for predictive value
Used in the acute patients with stroke
Limited use in trauma and idiopathic EICP
Optic Never Sheath, US and Trauma
• Enrolled 35 patients with a suspicion of EICP due to possible focal intracranial pathology
• 11 had CT results consistent with elevated ICP • All were correctly predicted by optic nerve sheath measurement of over 5 mm on US
• One patient with diameter of 5.7 mm in one eye and 3.7 in the other on US had a mass abutting the ipsilateral nerve without shift on CT
Optic Never Sheath, US and Trauma
• Mean diameter for the Mean diameter 11 patients with CT evidence of increased ICP was 6.23 mm (95% ICP 6.23 mm CI 5.6 to 6.87)
• Mean diameter for the Mean diameter others was 4.43 mm (95% CU 4.15 to 4.72)
• The difference of 1.8 mm (95% CI 1.23 to mm 2.38 mm) yielded a p = 0.001 Optic Never Sheath, US and Trauma
• Sensitivity 100%
• Specificity 94% • Positive predictive value of 92% • Negative predictive value 100% – Blaivas et al., Elevated intracranial pressure detected by bedside emergency ultrasonography of the optic nerve sheath. Acad Emerg Med. 2003 Apr;10(4):376‐81.
Optic Never Sheath and US
• Has been studied by numerous authors
• Studies range from case series to medium size prospective evaluations
• Both adults and children have been studied
• Varied setting including ED, ICU, operative suite and multiple pre‐
hospital settings
Optic Never Sheath and US
• Ocular ultrasound has already by studied in space
• Proven to yield quality images
• Optic nerve sheath diameter measured on multiple subjects
Optic Never Sheath and US
• In general there is good agreement that ONSD and ICP are related
• ONSD can be used as a surrogate for EICP
• The large, blinded, randomized, prospective study is still missing
• Some questions remain
Optic Never Sheath Doubts
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Copetti R, Cattarossi L. Optic nerve ultrasound: artifacts and real images. Intensive Care Med. 2009; 35:1488‐9
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“What the authors indicate as optic nerve on ultrasound examination is an artifact (acoustic shadow) probably raising from lamina cribrosa. The measurements that the authors report are not the optic nerve sheath diameter but the measurement of an artifactual image.”
Optic Never Sheath Doubts
• “Images of optic nerve that are obtained with CT or MRI are very different from ultrasound ones ONSD can be used as a surrogate for EICP.”
• “Optic nerve present a serpiginouse and medially running while in these papers optic nerve seem to run straight and centrally.”
Optic Never Sheath More Data
• More recent research continues to support ONSD
• Sixty‐three adult patients with subarachnoid hemorrhage (n = 34) or primary intracerebral hemorrhage (n = 29) requiring sedation and invasive ICP monitoring
• Moretti R, Pizzi B, Cassini F, Vivaldi N. Reliability of Optic Nerve Ultrasound for the Evaluation of Patients with Spontaneous Intracranial Hemorrhage. Neurocrit Care. 2009 Jul 28.
Optic Never Sheath More Data
• Ninety‐four ONSD measurements were analyzed. • 5.2 mm proved to be the optimal ONSD cut‐off point to predict raised ICP (>20 mmHg)
• 93.1% sensitivity (95% CI: 77.2‐99%) and 73.85% specificity (95% CI: 61.5‐84%).
• ONSD‐ICP correlation coefficient was 0.7042 (95% CI for r = 0.5850‐0.7936).
• Moretti R, Pizzi B, Cassini F, Vivaldi N. Reliability of Optic Nerve Ultrasound for the Evaluation of Patients with Spontaneous Intracranial Hemorrhage. Neurocrit Care. 2009 Jul 28.
Optic Never Sheath More Data
• The median interobserver • Moretti R, Pizzi B, Cassini F, ONSD difference was 0.25 mm. Vivaldi N. Reliability of Optic Nerve Ultrasound for the • CSF drainage to control Evaluation of Patients with elevated ICP caused a rapid and Spontaneous Intracranial significant reduction of ONSD Hemorrhage. Neurocrit Care. (from 5.89 +/‐ 0.61 to 5 +/‐ 0.33 2009 Jul 28.
mm, P < 0.01).
• “ONSD measurements proved to have a good reproducibility”
• “ONSD changes almost concurrently with CSF pressure variations”
Optic Never Sheath at Elevation
• Sutherland AI et al., Optic nerve sheath diameter, intracranial pressure and acute mountain sickness on Mount Everest: a longitudinal cohort study. Br J Sports Med. 2008; 42:183‐8
• Not quite the space station, but fairly high by early standards
Optic Never Sheath at Elevation
• Studied association of ONSD, as a correlate of intracranial pressure (ICP), with acute mountain sickness (AMS)
• 13 mountaineers (10 men, 3 women; aged 23‐52 years) on a British expedition to climb Mount Everest
• Scans were recorded at sea level, and 2000, 3700, 5200 and 6400 m. Optic Never Sheath at Elevation
• ONSD was positively associated with increasing altitude (0.10 mm increase in ONSD per 1000 m, 95% CI 0.05 to 0.14 mm) and AMS score (0.12 mm per score, 95% CI 0.06 to 0.18 mm)
• Resting heart rate increased (0.29 mm per 20 beats/min, 95% CI 0.17 to 0.41 mm) • Oxygen saturations (0.20 mm per 10% decrease, 95% CI 0.11 to 0.29 mm).
Optic Never Sheath in Space
• 5 or more cases of EICP with prolonged time in space station
• Elevated pressures confirmed in several
• MRIs showing optic nerve sheath edema
• Visual effects noted in one subject
• Could have significant implications for long space travel
Body Fluid Shifts in Space
• Well documented that fluid shifts occur throughout body
• Central venous pressure may be effected
• Pulmonary congestion may occur
• Pulmonary edema can be encountered at high altitude and may be fatal
Lung Pathology and US
• Fluid shifts occurring in zero or near zero gravity are difficult to track with physical examination and auscultation only
• Other pulmonary process such as trauma, infection and others are also possible and may be difficult to diagnose with physical examination only
• Turns out US is great for evaluation of lung pathology
Ultrasound of the Lung?
• Until recently considered somewhat of a joke concept
• Largest Internal Medicine texts stated “lungs are major inhibitor of ultrasound and there was no use interrogating the lungs”
• This has changed in recent years
• Initial use in North America was for detecting or ruling out pneumothorax
Ultrasound of the Lung
• This is something you are probably familiar with
• Some of the best work on pneumothorax diagnosis has been done by NASA researchers and their colleagues
• A critical diagnostic technique works in near zero gravity
Ultrasound of the Lung
• Why is this important? Because the physical exam of the lung is very poor!
• In cases of pneumonia auscultation lags behind CXR significantly
• EMS tension pneumothorax treated with needle thoracostomy erroneously in 26%
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Blaivas M. Inadequate needle thoracostomy rate in the pre‐hospital setting for presumed pneumothorax; an ultrasound study. J Ultrasound Med. In Press.
Ultrasound of the Lung
• What about air and ultrasound?
• The healthy lung does not transmit ultrasound adequately
• However, diseased lung often does, when the pleural surface is involved
Lung Ultrasound Basics
• Interface of lung surface with US and the artifacts created was the basis of lung ultrasound
• Large number of lung US artifacts have been described
• Based on these artifacts accurate diagnosis can be achieved
Lung Ultrasound Basics
• Interface of lung surface with US and the artifacts created was the basis of lung ultrasound
• Large number of lung US artifacts have been described
• Based on these artifacts accurate diagnosis can be achieved
• In the case of a PTX, one is ruled out is Lung Sliding is present
Lung Ultrasound Basics
• When lung sliding is absent in the correct clinical setting PTX is likely
• Near 100% certainty occurs in the setting of a Lung point
• Lung point is the interface between lung and intra‐
thoracic air from a PTX
Other Lung US Applications
• As lung increases in fluid content it become evident on ultrasound
• Pulmonary edema cardiac or otherwise is easily detected
• In fact, clinicians can track response of pulmonary edema to treatment
• Clearly very high accuracy
Acute Interstitial Syndrome
• Elementary sign is the comet tail, arising from the pleural line spreading to lower edge of the screen without fading
Acute Interstitial Syndrome
• Multiple B lines are needed to conclude interstitial syndrome
Acute Interstitial Syndrome
• Massive lung rockets, more specific for acute interstitial syndrome
Acute Interstitial Syndrome
• Massive lung rockets, more specific for acute interstitial syndrome
Accuracy of Diagnosis
• Evaluated 40 patients before, during and after hemodialysis
• Counted number of B‐lines visualized in 28 lung zones
• Correlated with EF, time elapsed, net volume of fluid removed, and subjective degree SOB
• Noble VE et al., Ultrasound assessment for extravascular lung water in patients undergoing hemodialysis. Time course for resolution. Chest. 2009; 135:1433‐9.
Accuracy of Diagnosis
• 34 of 40 patients had statistically significant reductions in the number of B‐lines from predialysis to the midpoint scan and from predialysis to postdialysis with a p value < 0.001
• B‐line resolution appears to occur real‐time as fluid is removed from the body
• Noble VE et al., Ultrasound assessment for extravascular lung water in patients undergoing hemodialysis. Time course for resolution. Chest. 2009; 135:1433‐9.
Pleural Effusions
• Can be very difficult to diagnose
• Diaz‐Guzman E, Budev MM. Accuracy of the physical examination in evaluating pleural effusion. Cleve Clin J Med. 2008; 75:297‐303.
• Even CXR can leave you wondering, is something consolidation or effusion
Pulmonary Contusion
• Frequently encountered in patients with PTX
• Seen in as many as 17% of patients
• Yale Trauma Registry
• Prospective longitudinal study of ICU patients with thoracic trauma
• Ultrasound compared to CXR and CT
Pulmonary Contusion
• Sensitivity of ultrasound was 0.94 for Pleural Effusion and 0.86 for Lung Contusion while specificity 0.99 and 0.97, respectively
• The likelihood ratio was 94 (r1) and 0.06 (r ) for PE and 28.6 (r1) and 0.14 (r ) for LC.
• “Ultrasound provides a reliable method for the assessment of chest trauma patients with acute respiratory failure”
Alveolar Consolidation (Pneumonia)
• Hepatization: lung starts to have echotexture of the liver
• Once consolidation reaches pleura US will be able to perfectly evaluate lung
Lung
• 1946 Denier described US for consolidation evaluation (in theory)
• See a tissue pattern instead of just air
• Boundaries: superficial one is regular, deep is jagged
Lung
Liver
Alveolar Consolidation (Pneumonia)
• How accurate is the technique?
• 49 patients: pneumonia was confirmed in 32 cases (65.3%).
Lung
• 31 (96.9%) positive lung US and 24 (75%) positive CXR
• In 8 (25%) cases, lung US was positive with a negative CXR. CT scan always confirmed US results
Lung
Liver
Dynamic Air‐Bronchograms
• May be very helpful in differentiating pneumonia severity
• Also tracking improvement
• Detection of air movement through an area that appears like an effusion
Dynamic Air‐Bronchograms
• May be very helpful in differentiating pneumonia severity
• Also tracking improvement
• Detection of air movement through an area that appears like an effusion
Dynamic Air‐Bronchograms
• May be very helpful in differentiating pneumonia severity
• Also tracking improvement
• Detection of air movement through an area that appears like an effusion
Pulmonary Abscess
• Within an alveolar
consolidation, a
hypoechoic rounded
image is visible
Pulmonary Abscess
• Consolidated lung and
fluid can be
distinguished in the
same location
ARDS
• Seen in a variety of patients
• Trauma
• Sepsis
• Chemical exposure
• Hypoxic injury
• Others
ARDS
• One of the challenges is early differentiation of ARDS from other pulmonary processes
• Ultrasound appears well adapted for this role
ARDS
• While some findings seem to overlap with those of pneumonia further differentiation is possible
ARDS
• Subpleural consolidations are seen in ARDS (left image) but not in pulmonary edema (right image)
Summary
• Ultrasound is a versatile tool
• Highly portable and accurate
• Ideal for space station long term missions
• Extent of utility is still be fully explored
Questions?