Intensively Ultrasonic
description
Transcript of Intensively Ultrasonic
Intensively Ultrasonic An introduction to the clinical use of ultrasound
in the critical care environment.Dr. Daniel Rankmore - 2011
Talk Outline1. the physics2. the equipment3. novel clinical uses4. vascular access5. final words
the physics
Ultrasound Physics
Mechanical Electric Energy
Reflection / Refraction / Attenuation
Sound Wave Propagation (Wave)
Vibrating Particles (Medium)
Electric Mechanical Energy
Pulse Echo & Piezoelectrics
Basic PrinciplesReflection• The change in direction of a sound wave at the
interface of two mediums.
Refraction• The change in direction of a sound wave due to a
change in speed.
Absorption• Mechanical to heat energy.
Scatter• As surfaces are not uniform reflection/refraction
results in multiple directions.
Basic PrinciplesAcoustic Windows• Positioning of the probe over tissues
Echogenicity• Hyperechoeic – highly reflective• Aechoiec – no reflections
Acoustic Impedance• Density of tissue & frequency effect speed.
Acoustic Attenuation• The gradual loss of energy through a medium.
ArtifactsShadowing• Reduced penetration due to highly
reflective surfaces. Eg. Bone.
Acoustic Enhancement• Distal enhancement due to relatively
reduced attenuation.
Reverberation• Sound ‘bounces’ between two highly
reflective objects.
KnobologyPower• On/Off
Gain• Degree of echo amplification.
Depth• Focus of beam and displayed depth
Doppler• Doppler = Doppler• 2D = No Doppler
the equipment
The MachineSonosite M-Turbo Sonosite S-Series
which probe to use
Frequency
↑Frequency
↑Detail
Pattern
Special Purpose
The Probes
Linear10-5MHz 38mm
Phase Array5-1MHz 21mm
Linear13-6MHz 25mm
Curvy-linear5-2 Mhz 60mm
LinearFreq – 13-6MhzMax Depth – 6cm
Applications:Vascular Access, PneumothoraxNerve Blockade, Muscloskeletal
CurvedFreq – 5-2 MhzMax Depth – 30cm
Applications:FAST, Major vessel ?AAA, HemothoraxPleurocentesis, Peracentesis, BladderHepatobiliary, Obstetrics
PhasedFreq – 5-1 MhzMax Depth – 35cm
Applications:Echocardiography
Drag picture to placeholder or click icon to add
novel clinical uses
Cliff Reid’s Blog
http://resusme.em.extrememember.com/
extensions to FAST
PneumothoraxExtended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax: experience at a community based level I trauma center.
- Injury. 2011 May;42(5):511-4. Epub 2010 Feb 10.
- 204 Patients. Clinical examination was positive in 17 patients (true positive in 13/21, 62%; 4 were false positive and 8 were false negative), CXR was positive in 16 (true positive in 15/19, 79%; 1 false positive, 4 missed and 2 CXR not performed before chest tube) patients and EFAST was positive in 21 patients (20 were true positive [95.2%], 1 false positive and 1 false negative). In diagnosing pneumothorax EFAST has significantly higher sensitivity compared to the CXR (P=0.02).
hqmeded.org23 yo male stabbed with a cooking fork (6min)
(Link)Thoracic ultrasound for pneumothorax (Link)
Pelvic Fractures Ultrasonic detemination of pubic symphyseal widening in trauma:
FAST-PS. J Emerg Med 2011 May 40(5):528-33 STUDY OBJECTIVES: We hypothesized that an ultrasound image of the PS as
part of the FAST examination (FAST-PS) would be an accurate method to determine if pubic symphysis diastasis was present.
RESULTS: Twenty-three trauma patients were evaluated with both plain radiographs and US (11 PM, 12 ED). Four patients had radiographic PS widening (3 PM, 1 ED) and 19 patients had radiographically normal PS width; all were correctly identified with US. US measurements were compared with plain X-ray study by Bland-Altman plot. With one exception, US measurements were within 2 standard deviations of the radiographic measurements and, therefore, have excellent agreement. The only exception was a patient with pubic symphysis wider than the US probe.
CONCLUSION: Bedsid ultrasound examination may be able to identify pubic symphysis widening in trauma patients. This potentially could lead to faster application of a pelvic binder and tamponade of bleeding.
vascular
Art Line InsertionUltrasound-guided catheterization of the radial artery: a systematic review and meta-analysis of randomized controlled trials.
- Chest. 2011 Mar;139(3):524-9. Epub 2010 Aug 19.
- Conclusion: Four trials with a total of 311 subjects were included in the review, with 152 subjects included in the palpation group and 159 in the ultrasound-guided group. Compared with the palpation method, ultrasound guidance for arterial catheterization was associated with a 71% improvement in the likelihood of first-attempt success (relative risk, 1.71; 95% CI, 1.25-2.32).
airway
Peadiatric ETT SizePrediction of pediatric endotracheal tube size by ultrasonography.- Acta Anaesthesiol Scand. 2011
Apr;55(4):422-8. doi: 10.1111/j.1399-6576.2010.02372.x. Epub 2011 Feb 2.
- Conclusion: Measuring subglottic airway diameter with ultrasonography facilitates the selection of appropriately sized ETTs in pediatric patients. This selection method better predicted optimal outer ETT diameter than standard age- and height-based formulas.
brains
Pre-hospital Transcranial DopplerPre-hospital transcranial Doppler in severe traumatic brain injury: a pilot study.
- Acta Anaesthesiol Scand. 2011 Apr;55(4):422-8. doi: 10.1111/j.1399-6576.2010.02372.x. Epub 2011 Feb 2.
- 18 patients. Matched GCS/MAP. 9 abnormal. Link with pupil changes and mortality.
- Conclusion: Our preliminary study suggests that TCD could be used in pre-hospital care to detect patients whose cerebral perfusion may be impaired
Post CrainectomyUse of ultrasonography in hemicraniectomized patients: a report of two cases.
- Intensive Care Med. 2010 Jun;36(6):1091-2.
- Zampieri and colleagues from Brazil report the use of brain ultrasound in two ICU patients who had had hemicraniectomies. ‘using the hemicraniectomy as an insonation window could be useful as a noninvasive triage tool and reduce the need for patient transport to the imaging center.’
Optic NerveUltrasound measurement of optic nerve sheath diameter in patients with a clinical suspicion of raised intracranial pressure.
- Emerg Med J. 2011 Aug;28(8):679-81. Epub 2010 Aug 15.
- To assess if ultrasound measurement of the optic nerve sheath diameter (ONSD) can accurately predict the presence of raised intracranial pressure (ICP). 26 patients. For any acute intracranial abnormality the value of ONSD was 100% specific (95% CI 76% to 100%) and 60% sensitive (95% CI 27% to 86%).
vascular accessIntroduction…
Transverse
Keeps other structures in view
Easiest to find vessel
LongitudinalCan be better for deeper
structuresAllows visualisation of
needle & wire advancing within the vessel
Which is the vein?1. Know the anatomy
Which is the vein?2. Static views on Ultrasound
1. Arteries have thicker walls
2. Arteries are rounder
Which is the vein?3. Dynamic views on Ultrasound
1. Compressibility Collapse vs. Winking
2. Doppler BART – Blue Away Red
Towards Flow – Pulsatile vs.
Continuous
vascular ultrasoundhow I use ultrasound for vascular access…
PreparationEquipment
Sonosite S Series – Linear 25mm – Gel/ Sock/ Opsite Tourniquet Gown/ Gloves Skin Prep – Chlorhex Local – 2-3ml 1% Lignocaine Line (IVC/ CVC/ PICC/ Vascath/ Art line) Flush – 20ml 0.9% N-Saline Dressing (Opsite/ Statlock/ Suture)
StaffPatient
sßcan the vesselConfirms the direction of
the vesselReveals anatomical
variations (and other structures)
Gives insight into patency (ie. thrombus)
identify the targetPrep the skinHold the probe lowOrientate the probeAdjust depth and gainVessel centralLocal anesthetic
advance on target Pencil grip @ 30-45 degrees Advance needle ‘I can’t see the needle!’
Stay midline Bright echogenic circle Shadow Do the jiggle Tenting Move the probe
Flashback Check the wire
hqmeded.orgUltrasound Guided Intravenous Peripheral
Placement (7min) - LinkUltrasound Guidance for Central Venous Catheter -
Link2 yo with DKA - Link
some final words…
think in three dimensions
Simplify the angles
Prior Preparation Prevents Piss Poor Performance
1. Optimise position (you & the patient)
2. Have an assistant (& talk to them)
3. Get the right equipment
4. Understand the equipment
5. Understand the anatomy
6. Know the complications (& what to do)
7. Practice
ReferencesMa JO, Mateer JR. Emergency Ultrasound. McGraw
Hill. 2003.Sangers RC, Winter R. Clinical Sonography: A
practical guide. Fourth Edition. Lippincott Williams & Wilkins. 2007.
WikipediaGoogle Images