Monday Back to Basics

Slit Lamp Basics

Revamped from our archives, the fabulous Dr. Alexis Pelletier-Bui teaches us how to use a slit lamp! This comprehensive post reviews all the knobs and buttons of the equipment, then shows how to use it to perform the exam.

COMPONENTS OF THE SLIT LAMP

(These photos are based on a Weiss SL 120 Slit Lamp – other models might be slightly different but the ideas are the same!)

Think of this part as a microscope.

#1 – Oculars – Adjust for your personal interpupillary distance

#2 – Magnification Dial – Can set to 5x, 8x, 12x, 20x, or 32x

#3 – Focusing Ring – Accounts for your personal refractive error.  If you have 20/20 vision or correction lenses, it should be set to 0. 

This part is your light source.  It can be swung 180 degrees side to side to allow for examination from the temporal or nasal side.

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#4 – Beam height – Move to the right of examiner > shorter.  

#5 – Beam widgth – Move to the right of the examiner > smaller

#6 – Color of light – 3 options: White (used for most of the exam), Cobalt blue (used with fluorescein exam), Green (aka red free filter; allows blood vessels to appear black; rarely used by ED doc)

#8 – Forehead Strap

#9 – Chin Rest

#10 – Height Adjustor – twist this to raise or lower the chin rest

#11 – Joystick – Allows movement of the viewing & illumination arms in tandem.  Large movements forward & backward are often required to obtain initial focus which will require pressure on the joystick to move the entire base.  Smaller microadjustments can be made with smaller movements of the joystick (without moving the base).  Movement side to side and up & down (the latter performed by twisting the joy stick) allow for you to examine different aspects of the eye (temporal to nasal, upper to lower lid, etc).

#12 – Light Brightness Knob – Most models have this component on the illumination arm but the Weiss SL 120 has this on the base.  Turn right > brighter

#13 – Locking Knob – May need to unlock to move the base.  Put the lock on if you are moving the whole slit lamp (i.e. in and out of the patient’s room)

PREPARING/POSITIONING

#14 – Table Height Adjustor – To increase patient comfort (and therefore compliance), lower or elevate the table as needed.  You may need to adjust your own chair height accordingly so try to use a stool.

#15 – Power Button – Make sure you’re plugged in!

PERFORMING A SLIT LAMP EXAM:

Step 1: Positioning your patient 

  • Adjust the height of the table to your patient
  • Make sure the patient’s chin is against the forehead strap or you will be unable to focus the slit lamp 
  • Align the lateral canthus of the patient with the red line on the supporting rod of the patient-positioning frame

Step 2: Position yourself

  • Adjust your stool so you can comfortably look in the oculars
  • Adjust the oculars to your interpupillary distance & the focusing ring to your refractive error
  • Pick your magnification (8x or 12x is a good start)

Step 3: Performing Diffuse Illumination

  • Move the illumination arm to 30 degrees off center, preferably to the temporal aspect of the eye you are examining (we usually avoid the nasal aspect because the illumination arm tends to hit the patient’s nose with movement of viewing & illumination arms)
  • Start with a tall & wide (3-8 mm) beam for your initial assessment
  • Adjust the light brightness to patient tolerance
  • Utilizing the white light, globally assess the eye with a systematic approach (i.e. the “Ls & Cs” – lids, lashes, lacrima, lens, limbus, conjunctiva, cornea & chamber [anterior])
  • Stain the eye with fluorescein then examine using the cobalt blue light (assess for corneal abrasions, ulcers, Seidel’s sign, herpes simplex, etc)

Step 4: Perform Direct Focal Illumination

  • Narrow the beam as thin as possible (~1 mm) but keep it tall
  • Maximize the light brightness
  • Move the illumination arm to 60 degrees off center – a curved quadrilateral block should become apparent (aka cornea parallelepiped – see below) – This allows for examination of the depth of the cornea

Photo source: Vislisel, J & Critser, B. Normal cornea. https://webeye.ophth.uiowa.edu/eyeforum/atlas/pages/Normal-Cornea/index.htm. Published June 2, 2015. Accessed July 3, 2020.

  • Next, shorten the beam height (~1 mm x 1 mm).
  • Keep the same max brightness and 60 degree angle.
  • Move your joystick until the space between the lightsource & the parelleliped is overlying the pupil. The black pupil will allow for visualization of cell and flare (see below).

Photo source: Root, T. “Cell and flare” in the eye (video). https://timroot.com/cell-and-flare-in-the-eye-video/. Accessed July 3, 2020.

Monday Back to Basics

Measles Part 1: Identification with Drs. Edward Guo and Simon Sarkisian

While most cases of measles are mild and will self-resolve, the high infectivity of the virus is a public health hazard due to rare complications of the disease that can cause long-term morbidity and mortality. Particularly high risk populations include unvaccinated individuals, children < 5 years, adults > 20, pregnant women, and immunocompromised patients.  

Look forward to part 2 for more details on measles management, treatment, and complications! 

References: 

https://www.nj.gov/health/cd/topics/measles.shtml

https://www.cdc.gov/measles/hcp/index.html

Takhar SS, Moran GJ. Serious Viral Infections. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e. McGraw-Hill Education; 2020. 

Nguyen M, Dunn AL. Rashes in Infants and Children. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e. McGraw-Hill Education; 2020. 

Monday Back to Basics

Preeclampsia Management with Dr. Erica Westlake

Use these medications for aggressive blood pressure control

Load patients with magnesium early

Ultimate treatment is delivery – involve OB/NICU teams early, transfer patients if these teams are not available

Referneces:

Monday Back to Basics

From the Archives: Postpartum Hemorrhage with Dr. Oskutis

References:

1. Shakur H, Elbourne D, Gülmezoglu M, et al. The WOMAN Trial (World Maternal Antifibrinolytic Trial): tranexamic acid for the treatment of postpartum haemorrhage: an international randomised, double blind placebo controlled trial. Trials. 2010;11:40. doi:10.1186/1745-6215-11-40.

2. American College of Obstetricians and Gynecologists (ACOG). Postpartum hemorrhage: ACOG practice bulletin no. 183. Obstet Gynecol. 2017;130:168-186.

Monday Back to Basics

From the Archives: Peptic Ulcer Disease and Gastritis by Dr. Angela Ugorets and Dr. Karen O’Brien

Peptic Ulcer Disease

Chronic illness, recurrent ulcers in stomach and duodenum most commonly due to H. Pylori and NSAIDs. 10% people in the western world will have this in their lifetime.

Symptoms:

  • Burning, gnawing, achy, “empty, hungry” epigastric pain
  • Relieved by ingestion of food (usually), milk, antacids (buffers/dilutes gastric acid)
  • Worsens after gastric emptying, classically the pain awakens patients at night
  • Chronic ulcers can be asymptomatic or cause painless GI bleeding
  • NOT (usually) related to PUD: pain after eating, nausea, belching
  • “Alarm features” for suspicion of cancer –> need more emergent endoscopy: >50 yo, weight loss, persistent vomiting, dysphagia/odynophagia, GIB, abdominal mass, lymphadenopathy, Family hx

Physical Exam: For uncomplicated PUD, expect benign physical exam +/- epigastric tenderness (not sensitive or specific). VS should be normal. 

Workup: Generally includes CBC to rule out anemia from chronic GIB. Consider LFT, lipase, EKG, trop, upright CXR, RUQ US to rule out other etiologist that may present similarly with epigastric pain if indicated. Gold standard for diagnosis is endoscopy.

Treatment

  • Stop NSAIDs 
  • Proton pump inhibitors: decrease acid secretion from gastric parietal cells, irreversibly bind with H+K+ATPase (proton pump).
    • Example: omeprazole, pantoprazole.
    • Heal ulcers faster than any other tx. 
  • H2 receptor antagonists: Inhibit action of histamine on H2 receptor on gastric parietal cells
    • Example: famotidine, ranitidine.
    • Dose should be adjusted for patients in renal failure. 
  • Sucralfate: covers ulcer crater, protects it and allows healing, but doesn’t relieve pain as well 
  • Antacids: buffer gastric acid. Use for breakthrough pain. (Ex: Mylanta, Rolaids, Tums, etc) 

Dispo: As long as uncomplicated (no bleed, obstruction, perforation, etc), can be discharged from ED with Rx for meds above and referral to PCP or GI.

Gastritis

  • Not the same as PUD
  • Acute or chronic inflammation of gastric mucosa (not discrete ulcers) 

Causes: ischemia, toxic effects of NSAIDs, steroids, bile, alcohol, H. Pylori, autoimmune processes that destroy gastric parietal cells 

Exam: epigastric pain, N/V. Often presents with GIB: hematemesis vs chronic anemia vs melena 

References:

Fashner J, Gitu AC. Diagnosis and Treatment of Peptic Ulcer Disease and H. pylori Infection. Am Fam Physician. 2015 Feb 15;91(4):236-42. PMID: 25955624.

Malfertheiner P, Chan FK, McColl KE. Peptic ulcer disease. Lancet. 2009 Oct 24;374(9699):1449-61. doi: 10.1016/S0140-6736(09)60938-7. Epub 2009 Aug 13. PMID: 19683340.

Monday Back to Basics

From the Archives: Baby, It’s Cold Outside: Death by Hypothermia with Dr. Kate Ginty

The Basics

  • On average, approximately 1300 Americans die of hypothermia each year 
  • These don’t all occur in cold mountain regions. Homelessness, mental illness and substance abuse are important risk factors, particularly in urban areas. 
  • Not all hypothermia cases are related to exposure! Other causes include hypoglycemia, hypothyroidism, hypoadrenalism, hypopituitarism, CNS dysfunction, drug intoxication, sepsis and dermal disease 
  • Hypothermia = core body temperature < 35 degrees C (95 degrees F) 
  • Mild hypothermia (32-35 degrees C): present with shivering, tachycardia, tachypnea and hypertension 
  • < 32 degrees C: shivering stops and HR and BP decrease; patients become confused, lethargic and then comatose; Reflexes are lost, RR increases; bronchorrea occurs; aspiration is common; cold diuresis and hemoconcentration occur 
  • As temp lowers, sinus bradycardia develops into atrial fibrillation with slow ventricular response to ventricular fibrillation to asystole. At temps < 30 degrees C, the risk for dysrhythmias increases

Rewarming and Management

  • Type of rewarming is based on cardiovascular status, NOT temperature 
  • Passive rewarming: removal from cold environment and wet clothes, insulation 
  • Active external rewarming: warm water immersion, heating blankets set at 40 degrees C, radiant heat, forced air 
  • Active core rewarming at 40 degrees C: Inhalation rewarming (warm air via the vent), heated IV fluids, GI tract lavage, bladder lavage, peritoneal lavage, pleural lavage, extracorporeal rewarming, mediastinal lavage by thoracotomy 
  • Remember to handle these patients gently to avoid precipitation of ventricular fibrillation!

ECMO in Hypothermic Arrest

  • The use of ECMO has been recommended as the rescue therapy of choice for hypothermic cardiac arrest for its ability to rapidly rewarm patients (8-12 degrees/hour) and provide complete cardiopulmonary support 
  • Studies have shown that patients with cardiac arrest have a rate of survival of 50% with the use of ECMO, whereas, at centers without ECMO, these same types of patients have a survival rate of only 10% 
  • Cases of survival with a good clinical outcome have been reported with core temperatures as low as 13 degrees Celsius and in cases requiring long transport with more than 5 hours of CPR!

Risk Factors for Poor Prognosis Despite Aggressive Therapy (ECMO, etc):

  • Clear history of cardiac arrest before cooling 
  • Obvious signs of irreversible death 
  • Core body temperature higher than 32 degrees Celsius with asystole 
  • Potassium greater than 12 mEq/L