Saint John EM Rounds – January 2021
Dr Luke Edgar
PGY1 iFMEM Program, Dalhousie University, Saint John
PGY1 iFMEM Program, Dalhousie University, Saint John
Reviewed & Edited by Dr. Mandy Peach
Case
A 44 year old male presents to your trauma bay with progressive confusion and altered level of consciousness for the past three days. Collateral history reveals possible recent recreational methamphetamine use. No specific abnormal neurological features or findings on history and physical. A full workup is performed and investigations reveal a left frontal intracerebral hematoma with the following CT head (Figure 1) and ECG (Figure 2):
1. What clinical (history and physical) features suggest an elevated intracranial pressure? [4, 5]
On history, suspect an elevated intracranial pressure with:
• headaches
• vomiting
• altered mental status (ranging and alternating from drowsiness to coma)
• visual changes (blurred, diplopia, photophobia)
• history of malignancy, trauma
On examination, suspect an elevated intracranial pressure with:
• Cushing triad: hypertension, bradycardia and irregular respiration. This is a sign of impending brain herniation
• pupils unequal, unreactive
• disc edema
• optic atrophy
• bulging anterior fontanelle (in infants)
• evidence of trauma
2. What features on ECG are in keeping with an elevated intracranial pressure? [1, 2, 6]
Elevations in ICP or brain injuries are commonly associated with the following ECG changes:
• “Cerebral” T waves: widespread giant T wave inversion
• Flat T waves
• ST elevation/depression
• QTc prolongation
• Sinus bradycardia (if seen assess for other features of Cushing triad)
• Increased U wave amplitude
• Osborn (J) waves
• Other dysrhythmias: sinus tachycardia, junctional rhythms, premature ventricular contractions, atrial fibrillation, AV blocks
ECG changes are common with elevated ICP and intracranial hemorrhage. Approximately 56% of patients with intracranial hemorrhage have associated ECG changes.
Most importantly, recognize that these ECG changes can mimic acute coronary syndromes. This is potentially dangerous as a misdiagnosis of STEMI in a patient with an intracranial bleed could lead to unnecessary thrombolytics or PCI. For this reason, keep an elevated ICP in mind when identifying the above ECG changes.
3. What is a cerebral T wave? [1, 5]
Cerebral T waves are deep, symmetric, inverted T-waves seen on an ECG in patients with large intracranial bleeds. They are typically widespread
4. What other causes, other than elevated ICP, result in inverted T waves and should be kept on your differential? [2]
When analyzing an ECG it is important to recognize other causes of inverted T waves. The differential for inverted T waves includes:
• Myocardial ischemia and infarction
• Bundle branch block
• Ventricular hypertrophy
• Pulmonary embolism
• Hypertrophic cardiomyopathy
5. What is the pathophysiological cause for the ECG changes associated with an elevated ICP? [3, 4]
The full pathophysiology of ECG changes related to an elevated ICP is not fully understood.
ECG changes related to an elevation in ICP are thought to be related to neurogenic cardiac injury. This is mostly due to a surge of systemic catecholamines as a result of significant sympathetic activation from the central neuroendocrine axis and activation of the adrenal glands. Additionally, any injury to the hypothalamus or insula can cause dysfunction of the autonomic nervous system and a systemic inflammatory response.
Systemic catecholamine levels can be elevated for as long as 10 days. This prolonged exposure to catecholamines as well as the systemic inflammatory response can result in cardiac injury and dysfunction.
It is also possible for the heart to suffer from “neurogenic stunned myocardium syndrome” (NSM). This is reversible myocyte damage that results in ECG changes, in addition to other cardiac effects, due an excessive release of norepinephrine. The amount of cardiac damage caused by NSM correlates with the degree of brain injury. NSM can develop within four hours of brain injury. Other causes of NSM include pheochromocytoma, near drowning, and severe emotional experiences.
6. What are the most common intracranial findings associated with ECG changes related to an increased ICP? [1, 3]
The most common causes of ECG changes related to an elevation in ICP involve massive intracranial hemorrhage, including subarachnoid hemorrhage (49 to 100% of cases)3 and intraparenchymal hemorrhage (57% of cases)1.
Less commonly, ECG changes are associated with massive ischemic stroke causing cerebral edema, traumatic brain injury, or less commonly cerebral metastases.
7. How long do ECG changes last with brain injuries related to elevated ICP, and what are the clinical implications for a finding of prolonged ECG changes? [3]
Normally, as brain injuries and elevated ICP resolve, so will ECG changes. Most ECG changes will resolve within three days but have been reported to last up to eight weeks from the etiology of the elevated ICP.
Some reports have shown that prolonged ECG changes are associated with an increased risk for ischemic neurological deficit, poor outcome, and death following a subarachnoid hemorrhage. Specifically, persistent prolonged QTc is associated with poor clinical outcomes and death, whereas recovery of QTc is associated with good clinical outcomes.
SUMMARY & KEY POINTS:
• Be aware of Cushing triad on clinical assessment of patients with potential elevation in ICP (sinus bradycardia, hypertension, and abnormal respiratory pattern).
• There are multiple nonspecific ECG changes associated with an elevation in ICP, including: cerebral T waves, ST elevation/depression, sinus bradycardia, increased U wave amplitude, J waves, and other dysrhythmias.
• The exact pathophysiology for the cause of elevated ICP causing ECG changes is complicated and not fully understood. It is thought to mostly be due to excess catecholamine and norepinephrine exposure, along with a dysregulated inflammatory reaction.
• Subarachnoid hemorrhage and intraparenchymal hemorrhage are the most common causes of ECG changes associated with elevated ICP.
• Be aware that ECG changes related to elevated ICP can mimic acute coronary syndrome, so keep intracranial pathologies on your differential when the above ECG changes are found.
Of note, the patient described in the clinical scenario was admitted to neurosurgery and observed for nearly two weeks. He recovered without operative management.
REFERENCES:
Gregory T and Smith M. Cardiovascular complications of brain injury, Continuing Education in Anaesthesia Critical Care & Pain. 2012; 12:2, 67–71. Available from: https://doi.org/10.1093/bjaceaccp/mkr058
Levis JT. ECG Diagnosis: Deep T Wave Inversions Associated with Intracranial Hemorrhage. Perm J. 2017; 21:16, 049. doi:10.7812/TPP/16-049
Pinto VL, Tadi P, Adeyinka A. Increased Intracranial Pressure. [Updated 2020 Jul 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482119/
Tannenbaum L. ECG Pointers: Intracranial Hemorrhage. emDocs.net: Electrocardiography. 2018; Last updated: November 14, 2018. Accessed: December 29, 2020. Available from: http://www.emdocs.net/ecg-pointers-intracranial-hemorrhage/
Yogendranathan N, Herath HM, Pahalagamage SP, Kulatunga A. Electrocardiographic changes mimicking acute coronary syndrome in a large intracranial tumour: A diagnostic dilemma. BMC Cardiovasc Disord. 2017;17(1):91. Published 2017 Apr 4. doi:10.1186/s12872-017-0525-2
Melanie Johnston, PGY2 iFMEM Dalhousie University Saint John
Reviewed by Dr. Mandy Peach
Introduction:
The highest incidence of nasal foreign bodies is in pediatric patients, ages 2-5.1 The removal of nasal foreign bodies in the emergency department can be challenging.
The most common objects removed are beads, nuts, chalk, eraser heads, pebbles, and other small objects.1,2 While most nasal foreign bodies are benign, some objects can cause severe damage and need to be urgently removed.
The diagnosis of nasal foreign may be obvious as the caregiver may have witnessed the event and present acutely. Others may have delayed presentations of weeks-months after the child develops symptoms of nasal irritation/infection from the retained foreign body. In general, organic foreign bodies (flowers, plants, bugs) tend to be more irritating to the nasal mucosa and cause symptoms much earlier.2
Details on history and physical exam findings that should raise suspicion of a potential nasal foreign body in a paediatric patient include:
Unilateral epistaxis
Nasal foreign bodies have the potential to dislodge posteriorly and aspirate.1 Consider aspirated FB if new wheeze/cough/shortness of breath in a child with suspected intranasal FB and be prepared for a precipitous change in the airway. 6
Nasal foreign bodies are most commonly located on the floor of the nasal passage under the inferior turbinate, or superiorly in front of the middle turbinate.2
Foreign bodies are most frequently located on the right side, due to the right handed dominance of most children.2
Figure 1. Anatomy of the nose.3
Examination:
Ensure good lighting to be able to visualize the canal. Place the patient in a sniffing position with caregiver assistance (they may have to firmly hold child for cooperation). Suction should be readily available for nasal discharge and to aid in visualization. Nasal speculum can be used to aid visualization of the canal. Visualization of the foreign body confirms the diagnosis.
Figure 2. Marble nasal foreign body in pediatric patient.4
ENT referral is warranted if:
– Foreign body suspected, but unable to visualize by anterior rhinoscopy
– Impacted foreign body with marked inflammation (eg button batteries)
– Penetrating foreign body
– Any foreign body that cannot be removed due to poor cooperation, bleeding, or limited instrumentation2
Foreign Body Removal Options:
There are a number of techniques for nasal foreign body removal in the Emergency Department: alligator forceps, suction, balloon catheters, cyanoacrylate glue.2 Depending on the patient, these methods can be technically challenging if the patient is uncooperative, and may require the use of procedural sedation. A less invasive alternative for children not willing to cooperate with manipulation in the nasal canal is the Mothers’ Kiss.
Mothers’ Kiss Technique:
This technique was first described in the 1960s by a general practitioner in New Jersey and uses positive pressure to mobilize the foreign body from the nasal passage.1 It is effective in approximately 60% of attempts5, and generally most effective for smooth/soft foreign bodies that totally occlude the anterior nasal cavity.2 Even when not successful, it may improve visibility of the foreign body. Theoretical risks include barotrauma to both the tympanic membranes or pneumothorax, but these complications have never been reported.5 The pressure used by the caregiver to attempt expulsion of the foreign body is equivalent to that of a sneeze, approximately 60mmHg.1 The main danger in removing a foreign body from the nose is the risk of aspiration.
Procedure:5
1) Instruct the caregiver to place their mouth over the childs’ open mouth, forming a firm seal (similar to mouth-to-mouth resuscitation).
2) Next, occlude the unaffected nostril with a finger
3) The caregiver should blow until they feel resistance (caused by the closure of the childs’ glottis), then they should deliver a short puff of air into the childs’ mouth
4) The puff of air travels through the nasopharynx, and if successful results in the expulsion of the foreign body
5) If unsuccessful, the procedure can be repeated a number of times
Figure 3: Caregiver performing “Mother’s Kiss”. Shows occlusion of unaffected nare,
with seal formed around childs’ mouth.
If the caregiver is unable to perform the procedure, the approach can be recreated with a bag-valve-mask as the positive pressure source, ensuring the mask covers only the childs’ mouth.
Figure 4: Positive Pressure Ventilation with Bag-Valve-Mask.6
For a visual review of these techniques, please refer to the following videos:
Bottom Line:
Nasal foreign bodies are a common occurrence in the paediatric population. Their removal in the Emergency Department can be challenging as the patient may be fearful and non-cooperative. While there are a number of methods for removal of nasal foreign bodies, the “Mothers’ Kiss” technique provides a relatively non-invasive alternative. It has been shown to be effective in removal of 60% of nasal foreign bodies, and is most effective if foreign bodies are smooth and located in the anterior nasal cavity. If the caregiver is unable to perform the procedure, the approach can be recreated with BVM as the positive pressure source. The risks of this technique are minimal, and even when unsuccessful, can assist in improving the visualization of the nasal foreign body.
References:
Isaacson, G., Ojo, A. (2020). Diagnosis and management of intranasal foreign bodies. Up to Date. Retrieved from https://www.uptodate.com/contents/diagnosis-and-management-of-intranasal-foreign-bodies.
Le, P. (2020). Anatomy, Head and Neck, Nasal Concha. Retrieved from: https://www.statpearls.com/ArticleLibrary/viewarticle/32550
Nose-Foreign Body Nose, Dr Vaishali Sangole. Retrieved Oct 31,2020 from: http://vaishalisangole.com/NOSE_Foreign.html
Glasziou, P., Bennett, J. (2013). Mothers’ kiss for nasal foreign bodies. Australian Family Physician, 42(5): https://www.racgp.org.au/afp/2013/may/mothers-kiss/.
Thoreckzo. (2017). Foreign Bodies in the Head and Neck. Pediatric Emergency Playbook. Retrieved from: https://pemplaybook.org/podcast/foreign-bodies-in-the-head-and-neck/
Pretel, M. Removing object from child’s nose using the kiss technique. Youtube- retrieved from: https://www.youtube.com/watch?v=RR3SxICqdAY.
Dudas, R. Nasal foreign body removal. Youtube- retrieved from: https://www.youtube.com/watch?v=PacvHiJFhNA.
Luke Edgar, BScH MD
PGY1 Family Medicine Integrated Emergency Medicine
Dalhousie Saint John
Reviewed by Dr. David Lewis
Hip fractures are a common and painful injury diagnosed and treated in the emergency department, with elderly patients representing the majority of cases. Advanced age, comorbidities, and increased sensitivity to side effects from systemic analgesia all pose challenges to achieving adequate pain control.1,2 Additionally, NSAID use in the elderly is frequently contraindicated due renal, cardiac, and gastrointestinal comorbidities as well as drug interactions. In elderly patients, both undertreated pain and opioid analgesia can precipitate delirium.3
Regional nerve blocks for the indication of hip and femoral neck fractures have been shown to reduce pain and need for IV opiates.1 Contraindications include infection over the injection site, patient refusal, and allergy to local anesthetic. Additionally, patients at risk for compartment syndrome (such as those with a concomitant ipsilateral tibial plateau fracture) should be selected cautiously as they may not reliably have increased pain after block.4
There are three main techniques described for regional nerve blocks to provide analgesia for hip and femoral neck fractures.1
Figure 1. Lower limb peripheral nerve sensory distribution.5 Circled in red are the nerves blocked using the fascia iliaca technique. Cutaneous distribution of the obturator nerve is not depicted but consists of a small area on the proximal medial thigh.
Table 1. Supplies and equipment for performing a fascia iliaca nerve block
Table 2. Steps to complete a fascia iliaca nerve block6
Table 3. One person technique – Steps to complete a fascia iliaca nerve block
Figure 2. Video demonstrating the sonoanatomy of the right femoral triangle. From lateral to medial, femoral nerve, artery and vein (NAVel), labeled with yellow, red, and blue arrows, respectively.
Figure 3. Sonoanatomy of the right femoral triangle, transverse view for the fascia iliaca nerve block.
Figure 4. Sonoanatomy of the right femoral triangle demonstrating ultrasound-guided needle placement using an in-plane technique. Note two pops should be felt as the needle crossed the two fascial planes.
For a visual review of these steps and ultrasonographic landmarks, please see the following videos and webpage by EM Ottawa, 5 Minute Sono, and NYSORA:
Serious complications of this procedure are rare, but present.
Femoral nerve blocks are recommended for hip and femoral fractures to reduce pain and opioid analgesia requirements. Given that poor pain control and opioid analgesia are risk factors for delirium in elderly patients, hip blocks may also reduce rates of delirium (further study required). A fascia iliaca block with 20 cc of 0.5% bupivacaine is a well described technique with very few contraindications. To reduce the risk of complications, these blocks should be completed using sterile technique under ultrasound guidance with the help of an assistant. Hip broke? Hip block.
Dr. Sultan Alrobaian (PEM Fellow and Dalhousie PoCUS Fellow, Saint John, NB, Canada)
Reviewed by Dr. David Lewis
© 2020 UpToDate, Inc. and/or its affiliates. All Rights Reserved.
© 2020 UpToDate, Inc. and/or its affiliates. All Rights Reserved.
© 2020 UpToDate, Inc. and/or its affiliates. All Rights Reserved.
© 2020 UpToDate, Inc. and/or its affiliates. All Rights Reserved.
1.Lotterman S, Sohal M. Ear Foreign Body Removal. [Updated 2019 Jun 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459136/
3.Heim S W, Maughan K L. Foreign bodies in the ear, nose, and throat. Am Fam Physician. 2007;76(08):1185–1189. [PubMed] [Google Scholar]
4.Awad AH, ElTaher M. ENT Foreign Bodies: An Experience. Int Arch Otorhinolaryngol. 2018;22(2):146–151. doi:10.1055/s-0037-1603922
Dr. Colin Rouse– (PGY-3 CCFP Emergency Medicine) | Dalhousie University
and Dr. Sultan Alrobaian (Dalhousie PoCUS Fellow, Saint John, NB, Canada)
Reviewed by Dr. David Lewis
A 70 year of woman present to the ED with a history of fever, cough and dyspnoea. After a full clinical assessment (with appropriate PPE), Lung PoCUS is performed.
The Covid-19 Pandemic has created the largest international public health crisis in decades. It has fundamentally changed both societal norms and health care delivery worldwide. Changes have been implemented into resuscitation protocols including ACLS to prioritise appropriate donning of personal protective equipment (PPE) and consideration of resuscitation appropriateness prior to patient contact.1 Equipment has been removed from rooms to limit cross-contamination between patients. In this Pearl we will explore why PoCUS should not be discarded as an unnecessary tool and should be strongly considered in the assessment of a potential Covid Patient.
Disclaimer: Given the novel nature of CoVid-19 there is a lack of RCT data to support the use of PoCUS. These recommendations are based solely on expert opinion and case reports until superior evidence becomes available.
The assessment of the potential Covid-19 patient.
First one must consider the potential risk for coronavirus transmission at each patient encounter and ensure proper PPE2 for both oneself and the PoCUS device3.
Confluent B Lines and small sub pleural consolidation
Patchy B lines and Irregular pleura
Irregular pleura
Air Bronchogram
It has been noted that lung abnormalities may develop before clinical manifestations and nucleic acid detection with some experts recommending early Chest CT for screening suspected patients.10 Obviously there are challenges with this recommendation mainly regarding feasibility and infection control. A group of researchers in China compared Ultrasound and CT findings in 20 patients with COVID-19. Their findings are summarized in the table below:
Their conclusion was that ultrasound has a major utility for management of COVID-19 due to its safety, repeatability, absence of radiation, low cost and point of care use. CT can be reserved for patients with a clinical question not answered by PoCUS. CT is required to assess for pneumonia that does not extend to the pleura. Scatter artifact from aerated lung obscures visualization of deep lung pathology with PoCUS. When PoCUS is sufficient it can be used to assess disease severity at presentation, track disease evolution, monitor lung recruitment maneuvers and prone positioning and guide decisions related to weaning of mechanical ventilation.
Dr. Devon Webster – PGY2 FMEM Dalhousie University, Saint John NB
Reviewed by Dr. David Lewis
Claude Virchow is a 59-year-old gentleman who presents to your emergency department complaining of pain to his medial right leg. 2 days ago, he bumped his knee and since then, has developed a hard, rope-like, tender swelling along the inside of his knee. On exam, you see the following image and he winces as you palpate along the indurated cord.
Figure 1 Source
In the next bed over, is a 39-year-old man presents with similar induration along his antecubital fossa bilaterally. He has a history of IVDU and was seen a week prior for the same problem. He is back as the indurated areas seem to be extending and his pain is worsening despite abstinence from injection and adherence to conservative measures. There are no signs of infection.
What are your recommendations?
Figure 2 Source
Figure 3 Source
Figure 4 Approach to lower limb superficial thrombophlebitis. Source: Thrombosis Canada
Renee Amiro – PGY3 FMEM Dalhousie University, Saint John NB
Reviewed by Dr. Kavish Chandra
A two-month-old male presents with his mother to the emergency department with two tightly wound hairs around his fourth and fifth toes. He is visibly upset and crying excessively. His mother says that his toes looked like this when he woke up this morning. He is otherwise well and has had his two-month immunizations.
His toes look like this:
Definition – a tightly wound hair, thread, rubber band that is wrapped around an appendage and causes impaired blood flow.
Why this is bad – the constriction causes edema which restricts venous blood flow causes more edema which then impedes arterial blood flow and that can cause ischemia and if left undetected could cause amputation.
Most common appendages involved – Toes, external genitalia, fingers
Most common presenting symptom – excessively crying young child or swollen appendage found by mom or dad.
Goal is to remove the restricting band ASAP!
Remember to treat pain! Using emla gel on the digit prior to any manipulation and use other analgesics as you deem appropriate. Remember the use of sugar for pain management in babies.
In all management types- ensure you have gotten all of the hair and have released the constricted band completely.
Copyedited by Kavish Chandra
References
Lin, Michelle 2012. https://www.aliem.com/trick-of-trade-hair-tourniquet-release/
Fox, Sean 2015. https://pedemmorsels.com/hair-tourniquet/
Patricia Marks – PGY1 (FRCPC) Dalhousie University, Halifax, NS
Reviewed by Dr David Lewis
Supraventricular tachycardias (SVT) is a common presentation to the emergency room, and most patients will require treatment with adenosine or electrical cardioversion, as vagal maneuvers are less than 20% of the time in clinical practice. Adenosine and electrical cardioversion both require additional hospital resources, and adenosine is poorly tolerated by patients.
The REVERT trial published in 2015 in the Lancet by Appelboam et al. proposed a modified Valsalva maneuver in the treatment of SVT. The study was a multicentre randomized control trial in England involving 433 patients with stable SVT. According to an intention to treat analysis, the authors found a 43% success rate of conversion to sinus rhythm with the modified Valsalva maneuver compared to 17% with standard Valsalva. No significant dangerous adverse effects occurred in this study.
*The REVERT trial used a manometer to measure 40mmHg of pressure, however Smith and Boyle have demonstrated that 40mmHg of pressure is generated when a patient is instructed to blow into a 10cc syringe until the plunger moves
Image obtained from https://www.ecgmedicaltraining.com/wp-content/uploads/2016/06/REVERT-Trial-SVT.jpg on February 21, 2020.
Watch the REVERT authors perform the maneuver:
In adults with stable SVT, the modified Valsalva maneuver as published in the REVERT trial achieves a high rate of conversion to sinus rhythm with a NNT of 3.8 and without significant adverse effects. In patients without contraindications, the modified Valsalva maneuver is a low-cost and easy to teach strategy that should be trialled to convert patients in SVT prior to adenosine or electrical cardioversion.
Allyson Cornelis – PGY3 FMEM Dalhousie University, Saint John NB
Reviewed by Dr. Kavish Chandra
Lumbar punctures (LPs) are an essential emergency physician skill. Indications including assessing for serious causes of headaches such as meningitis and subarachnoid hemorrhage.
Various limitations to successful lumbar puncture include a large body habitus, arthritic spines, and altered spinal anatomy. Furthermore, this leads to increased procedural risks (failed attempts, pain, hematoma formation, infection and traumatic tap leading to difficult CSF interpretation)
The traditional way to perform a LP is using surface landmarks. The superior iliac crests are identified and a line is drawn across the back to connect them. This helps in identifying L3/L4 space. This is deemed a safe place for LP as the spinal cord ends above this.
Ultrasound has become a common tool used in the emergency department for assessment of patients and to assist in certain procedures. Lumbar puncture is one procedure where ultrasound has potential to increase success.1,2
The evidence
Meta-analysis of PoCUS guided LPs in the ED with adult and pediatric patients showed improved success rates (NNT 11) and fewer traumatic taps (NNT 6), less pain and less time to obtaining a CSF sample.4
Similar studies in neonates and infants showed reduced LP failure and traumatic taps in the PoCUS guided LP group.5
The procedure
The goal of the LP is to place a needle into the subarachnoid space where the CSF can be sampled. At the safe level, LP needle moves in-between the caudal equina.
Adapted from Tintinalli’s Emergency Medicine : A Comprehensive Study Guide, 8th ed.
Landmark based LP (briefly)
Place the patient in the lateral decubitus or seated position, allowing them to curve their spine and open the space between adjacent spinous processes
Identify the superior iliac spines and connect a line between the two iliac spines across the back (this should intersect the L4 spinous process).
LP can be safely performed in the L3/4 or L4/5 interspaces. During the procedure, the needle is directed towards the patient’s umbilicus.
PoCUS guided LP2,3,6
Identify the midline
Identify the interspaces
Ultrasound is a tool being utilized more often in clinical practice, including in the emergency department. Research shows that its use in obtaining lumbar punctures has potential benefits, including more success in obtaining a CSF sample and less traumatic taps, with minimal harms or downsides to use of the ultrasound.
Copyedited by Kavish Chandra
Resources:
Dr. Scott Foley – CCFP-EM PGY3 Dalhousie University, Halifax NS
Reviewed by Dr. David Lewis
When colour Doppler is initiated, the machine uses the principals of the Doppler effect to determine the direction of movement of the tissues off which it is reflecting.
The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to a wave source. It was named after the Austrian physicist Christian Doppler who first described the phenomenon in 1842. The classic example is the change in pitch of a siren heard from an ambulance as it moves towards and away from an observer.
These principles are applied to POCUS in the form of colour Doppler where direction of flow is reflected by the colour (Red = moving towards the probe, Blue = moving away from the probe), and the velocity of the flow is reflected by the intensity of the colour (brighter colour = higher velocity).
*Note: the colour does not represent venous versus arterial flow.
The use of colour Doppler ultrasound can be useful in the emergency department to determine vascular flow in peripheral vessels as well as through the heart. It is one way to determine cardiac valve competency by focusing on flow through each valve.
To optimize valve assessment, proper views of each valve must be obtained. It is best to have the direction of the ultrasound waves be parallel to the direction of flow. External landmarks for the views used are seen below:
Parasternal long axis: MV, AV
Parasternal short axis: PV, TV
Apical 4 chamber: TV, MV
How to examine valvular competency:
See video tutorial below for more
Mitral Regurgitation A4C
Tricuspid Regurgitation A4C
Aortic Stenosis PSLA
Color flow Doppler on POCUS is a straightforward way to assess for valvular competency in the Emergency Department. A more detailed valvular assessment requires skill, knowledge and experience.
Dr. Devon Webster – PGY2 FMEM Dalhousie University, Saint John NB
Reviewed by Dr. Kavish Chandra
It’s a quiet night in RAZ and you pick up your next chart- a 68 year old Ms. Iris Snellen has come in with new onset, painless, monocular vision loss. You pick up the ophthalmoscope to perform fundoscopy, and despite your best attempts, like many ED physicians before you, you see nothing helpful. So instead you pick up your investigative tool of choice, the ultrasound probe, and begin your ocular POCUS exam…
The retina is composed of multiple layers of neurons that allow for the human eye to convert light energy (photons) into images within the occipital brain. The retina sits on top of the vascular choroid which provides blood flow.
Fundoscopy allows for visualization of the following structures:
PoCUS is adjunctive test to assess for vision-threatening and common conditions impacting the eye such as retinal detachment (RD), posterior vitreous detachment (VD) and vitreous hemorrhage (VH).
A normal eye should allow you to visualize the following structures:
In retinal detachment, the retina is separated from the choroid either through formation of a hole in the retina, peeling away from the choroid if attached to the vitreous humour or through edematous infiltration between the two layers. Separation results in rapid ischemia and death of photoreceptors with subsequent vision-loss.
Posterior vitreous detachment is common and occurs secondary liquification of the gel-like vitreous body.
Vitreous hemorrhage can occur secondary trauma, spontaneous retinal tears or vitreous detachment or any cause of retinal neovasculiarzation such as in diabetes.
When assessing your pt, a retinal detachment should be at the top of your list of diagnoses to rule out given that prompt recognition and referral to ophthalmology may be a vision-saving intervention.
On history she may describe the following features of RD:
Assess for risk factors for retinal detachment:
Physical exam:
Your DDx may include:
(see below for distinguishing features of the DDx)
Most ED physicians feel more comfortable with their ultrasonography skills over their fundoscopy skills. PoCUS is a fast, portable and radiation-free approach to assessing patients for potential vision-threatening pathology such as retinal detachment. While ultrasonography should not replace ophthalmologic assessment and fundoscopy, it can be used as an additional tool to support your primary diagnosis.
Most recently, Lanham, et al., published a prospective diagnostic study involving 225 patients and 75 ED providers that found POCUS was 96.9% sensitive and 88.1% specific for the diagnosis of retinal detachment1. While studies have varied in whether sensitivity was better than specificity or vice versa, ultimately each study has shown that when trained, emergency providers are quite good at identifying RD by US2,3. In addition to RD, Lanham, et al further found ED providers did well at identifying vitreous hemorrhage (sens 81.9%, sp 82.3%) and vitreous detachment (sens 42.5%, sp 96%).
Get the PoCUS Scan:
Resources: