UMEM Educational Pearls

Pool Cleaner Toxicity - Chlorine Gas Exposure 

The "shock" treatment that is utilized in pool cleaner is often contained in a large plastic container and is calcium hypochlorite. Chlorine gas accumulates in the small amount of airspace found in the container. If a future patient opens the container either in an enclosed space or within close proximity of the face that allows for large inhalational exposure.

• Toxicity looks like CHF with hypoxia, rales and acute lung injury on CxR
• Chlorine gas will bind hydrogen ion in the aveoli forming HCl - hydrochloric acid
• Nebulized NaHCO3 would theoretically neutralize this acid but has not been found to improve clinical outcome though it has been found to improve symptoms.
• Supportive care and observation including CxR  4-6 hours after exposure are necessary since the effects of the chlorine gas may be delayed.

• Respiratory drive can be affected by injury to certain parts of the brain.  This is often seen in patients with traumatic brain injury (TBI).

• In the setting of TBI, recognizing abnormalities in respirations can be helpful in localizing the injury.

• Cheyne-Stokes respiration, in which breathing is rapid for a period and then absent for a period, is associated with injury to the cerebral hemispheres or diencephalon.

• Hyperventilation can occur when the brain stem or tegmentum is injured.

Superior Vana Cava Synrome....when to suspect

Two common causes of SVC syndrome include thrombus (secondary to CV catheters) and lung tumors/lymphoma

Consider this diagnosis in patients with a history of cancer and/or who have a central line in place and the complaint of facial swelling. Patients may not look swollen to you.

In addition, make sure to look at their necks and chest wall-presence of asymmetric, prominent veins should prompt consideration for this diagnosis. 

A useful clinical tool is to look at the patient's driver's license (assuming they have one) and compare to their appearance on presentation.

Workup in most cases will involve a CT of the chest.

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COPD and mechanical ventilation

• In some studies, the failure rate of non-invasive positive pressure ventilation (CPAP, BiPAP) in acute exacerbations of COPD has been as high as 50%
• When setting the ventilator in patients with COPD, keep in mind that the majority have chronic ventilatory failure with a chronic compensatory respiratory acidosis
• Pearl: Look at the serum bicarbonate level obtained from a recent period of stability
• A recent serum bicarbonate level can provide an indirect indication of the patient's baseline P_aCO₂ if you have no prior ABGs
• Rather than target a P_aCO₂ of 40 mm Hg, manipulate the ventilator to target the patient's baseline serum bicarbonate or a pH of 7.35 - 7.38.

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Extensor Tendon Injuries [Mallet Finger]

• Due to jamming the finger or to use a Pittsburgh term "stoving it".
• Can result in a swan neck deformity or permanent flexion of the DIP joint.
• Due to stretching of the extensor tendon,or avulsion of the extensor tendon off the distal phalanx.
• Approximately 50% will develop a complication.
• Conservative treatment is splinting the DIP joint in full extension for 5-6 weeks. 
  • The DIP joint must not be flexed for the full treatment period.
  • If the patient does flex their DIP, the 5-6 week time frame needs to completely restart.
• Due to the high complication rate all of these patients should be referred to a hand specialist early.

According to the most recent (2007 Updated) ACC/AHA Guidelines for management of STEMI, the ECG is one of the most important tools to assess for successful reperfusion after thrombolytics. The treating physician should assess the ECG at 90 minutes after administration of lytics. Failure of the ST elevation to decrease by at least 50% in magnitude in the lead with the greatest initial amount of ST elevation is an indication of failed thrombolysis...regardless of whether or not the patient has persistent symptoms. In fact, the Guidelines specifically state that signs and symptoms are considered unreliable indicators of successful reperfusion.

Patients with ECG evidence of failed thrombolysis at 90 minutes should be referred for emergent PCI ("rescue PCI").

Retropharyngeal Abscess

• Retropharyngeal Abscess is primarily a disease of younger children
• Origin may be medical or traumatic (ie running with popsicle stick in mouth).
• Complications:
  • Airway compromise
  • Sepsis
  • Mediastinal extension or invasion into other local structures
• Presentation:
  • Neck Pain – most common
    • Limitation of neck movement, especially neck extension
    • Torticollis
  • Fever
  • Sore throat
  • Neck mass
  • Respiratory distress, stridor – rarely
• Consider retropharyngeal abscess in pt with fever and limitation of neck mobility even in the absence of respiratory symptoms.
  • Were you considering Meningitis (fever and neck pain) and the LP results are normal? Think of retropharyngeal abscess.
     

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 Toxicology Trivia for $1000 - These are in fruits of the "rose" family and in some roots that contain cyanogenic glycosides and other cyanide containing compounds. It would actually take a fair amount of work to ingest enough to reach toxicity:

• Bitter almonds
• Apricot kernels
• Peach pits
• Plum sees
• Apple and pear seeds
• Cassava (actually have to wash the root prior to eating - skin contains the CN)
• Lima Beans

• Fractures of the orbital floor typically result from direct, blunt trauma with a rounded object to the eye. 

• When describing associated ophthalmic and/or neurologic injury, to consultants in particular, be aware of appropriate terminology to use in relaying the presence or absence of related physical findings.

• The following ophthalmic abnormalities are commonly associated with orbitla floor fractures:

              -- Enophthalmos (eye receded into the orbit) may occur when globe is 

                  displaced posteriorly, often with prolapse of tissue into maxillary sinus.

              -- Orbital dystopia (affected eye in a  lower horizontal plane than the other) may

                  occur due to the pulling of entrapped muscle and orbital fat.

• Remember to check for facial sensation, as decreased sensation along the ipsilateral cheek, upper lip, or upper gingiva suggests injury to the infraorbital nerve.

• The presence of a teardrop-shaped pupil suggests that the globe ruptured.

Acute Lung Injury (ALI) / Acute Respiratory Distress Syndrome (ARDS)

• ALI and ARDS are defined as:
  • bilateral pulmonary infiltrates on CXR
  • pulmonary capillary wedge pressure < 18 mm Hg (no heart failure)
  • P_aO₂ / F_iO₂ < 300 = ALI
  • P_aO₂ / F_iO₂ < 200 = ARDS  
• The current management for patients with ALI or ARDS is low tidal volume ventilation and a conservative fluid management strategy
• Two recent trials (EXPRESS and LOVS) evaluated different applications of PEEP in patients with ALI/ARDS
• Both studies evaluated lower levels of PEEP (5-10) vs. higher levels of PEEP titrated to plateau pressure
• Bottom line: different PEEP strategies did not influence survival, although higher levels did result in improved oxygenation.

Management of Ruptured AV Fistula

This pearl pertains to a case I had 2 weeks ago. A 65 yo male presented with a massively swollen left forearm in the region of his AV fistula. On ultrasound he had a 6 X 6 cm aneurysm. He was seen by vascular and transplant surgery and taken to the OR for repair.

So, the question came up, what would an emergency physician do if this bad boy actually ruptured? Well, obviously we would hold pressure. But what if that didn't work? Well, shouldn't the patient go to the OR? The answer is a resounding yes, but what if there is no surgeon around. There is not much literature on how to handle this devastating vascular catastrophe.

As a rule of thumb, if an AV Fistula ruptures (not leaks) and the patient is exsanguinating in front of you:

• Strongly consider a tourniquet (don't worry about the arm, they are about to die). Yes, that is right, a tourniquet. Sounds like common sense, but according to the vascular surgeons I have spoken with, too often this isn't done, and the patient ends up dying. If the patient is dying, tie the arm off.
• Consult a vascular surgeon ASAP

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Brugada syndrome, believed to be responsible for up to 4-5% of all episodes of cardiac arrest, has now been associated with atrial fibrillation as well (atrial fibrillation is the most common atrial dysrhythmia associated with Brugada syndrome). Patients with atrial fibrillation that have a full or incomplete right bundle branch block with ST segment elevation in leads V1-V2 should be referred to an electrophysiologist for evaluation of Brugada syndrome. The best treatment for these patients is still placement of an ICD.
 

Posterior Interosseous Nerve Compression Syndrome

As eluded to last week Posterior Interosseous Nerve (PIN) Compression Syndrome, a deep branch of the radial nerve, is felt to be radial tunnel syndrome with paralysis.

• Symptoms depend on whether the PIN is compressed before or after it divides into medial and lateral branches.
  • Before: Results in complete paralysis of the digital extensors, and extensor Capri ulnaris. Wrist will become dorsoradial deviated.
  • After-Medial Branch: Paralysis of extensor carpi ulnaris, extensor digiti quinti, and extensor digitorum communis
  • After-Lateral Branch: Paralysis of abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis proprius
• Common causes:
  • Synovitis and Joint Ganglions
  • Nerve compression following fracture repair
  • Idiopathic Compression can occur at these sites
    • Fibrous bands anterior to the radial head
    • Tendinous origin of Extensor Carpri Radialis Brevis
    • Arcade of Froshe –Most common, it is the tendinous proximal border of supinator
    • Distal Edge of Supinator –Least Common
• Exam:
  • Increased pain with resisted supination of the forearm
  • Supination with Wrist Flexion symptoms will likely be reproduced.
  • Pain with resisted extension of the middle finger
  • Unable to extend thumbs or fingers at MCP joints, but can extend at PIP and DIP joints

Topical Lidocaine for Acute Otitis Media

• Up to 83% of children with have AOM at least once by their 3rd birthday.
• In 2006, the AAP supported a “wait-and-see” plan for antibiotic prescription
  • Who can you withhold abx on?
    • Older than 6months
    • No severe infections (T>39°C)
    • If yes to both, may hold Abx for 48 hours.
• This approach does not mean “No treatment.”  Pain management is imperative.
  • Oral Analgesics are recommended in all cases.
  • Topical aqueous 2% licocaine eardrops also provide Rapid Pain Relief
    • Randomized, double-blinded, placebo-control study of topical lidocaine vs. placebo (water) demonstrated decreased pain scores at 10, 20, and 30 minutes after administration.
    • These can also be used safely at home for a few days.
       

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• Adolescents abuse inhalational agents due to lack of access to ETOH and illicit drugs
• Often halogenated hydrocarbon propellants like computer cleaner and paint stripper
• Sensitizes the myocardium to catecholamines
• Child is caught huffing and is frightened causing a catecholamines surge then v-fib arrest
• This was reported in a 1970 case series and "Sudden Sniffing Death" was coined (1)
• Actual treatment would be to administer B-Blocker in this instance (theoretical)

Bass. Sudden Sniffing Death. JAMA 1970.

• 85% of TIA's last less than an hour.
• 25% of strokes are preceded by a TIA.

Propofol Infusion Syndrome

• Many of us are now using propofol for sedation in our critically ill patients
• Although a great drug, it is important to be aware of "propofol infusion syndrome" (PIS)
• Risk factors for PIS include young age, severe CNS or pulmonary illness, and exogenous catecholamine administration
• Clinical features include: unexplained metabolic acidosis, rhabdomyolysis, hyperlipidemia, hepatomegaly, and cardiovascular instability
• Pearl: It is reported that the development of coved ST elevations in V1-V3 (similar to Brugada syndrome) may be the first sign of cardiac instability with PIS

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Side Effects of Hydrochlorothiazide

 Consider the following when prescribing HCTZ from the emergency department:

The side effects of hydrochlorothiazide include hypokalemia,hypercalcemia, hypomagnesemia, metabolic alkalosis, hyponatremia, hyperuricemia (may worsen gout), hyperglycemia, hypercholesterolemia, hypertriglyceridemia.

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The three factors that are most predictive of an arrhythmia as the cause of a syncopal episode are, in order:
1. abnormal ECG
2. history of CHF
3. age > 65

Overall, approximately 15-20% of cases of syncope are determined to be caused by an arrhythmia.

For those at the University of Maryland that got the chance to hear my lecture this week, you learned about Cubital tunnel syndrome [ulnar neuropathy], the second most common compressive neuropathy.  Carpal Tunnel syndrome remains the number one compressive neuropathy, and this pearl, for the sake of completeness, will address Radial tunnel syndrome.

Radial Tunnel Syndrome

• Believed to be due to overuse, frequently due to excessive elbow extension or forearm rotation.
• May actually just be an early stage of posterior interosseous nerve syndrome.
• Due to compression of the radial nerve as it passes a fibrous band that is attached to the radiocapitellar joint, and the tendinous origins of two muscles, extersor carpi radialis brevis and the supinator.
• Patients typically have l pain along the anteriolateral forearm.
• Pain is increased by extending the elbow and pronating the forearm.
• This syndrome is associated mostly with pain
• Weakness and numbness are not often seen.

Stay tuned for next week for Posterior Interosseous Nerve syndrome.