UMEM Educational Pearls

High Frequency Oscillatory Ventilation (HFOV)

• Although traditionally used in neonates, HFOV is becoming increasingly popular for select adult patients with ALI/ARDS.
• Benefits of HFOV include:
  • use of smaller tidal volumes than conventional ventilation
  • maintains alveoli open at a relatively constant airway pressure thereby preventing atelectrauma
  • improves ventilation/perfusion
• Indications for use of HFOV are when:
  • conventional ventilator settings require an F_iO₂ > 70% and PEEP > 14 cm H₂O OR
  • pH < 7.25 despite higher tidal volumes and plateau pressures > 30 cm H₂O
• Key variables, along with suggested initial settings, for HFOV include:
  • Frequency: 4 - 7 Hertz
  • Amplitude: 70 - 90 cm H₂O
  • Mean airway pressure: 5 cm H₂O greater than last plateau pressure measured on conventional setting
  • Bias flow: 40 L/min
  • Inspiratory time: 33%
  • F_iO₂: 100%

Show References

Beware of older patients with groin pain!

Lower abdominal pain (mimicking diverticulitis) and isolated groin/hip pain are relatively common presentations of AAA and iliac artery aneurysm and rupture. As many as 15-20% of symptomatic AAAs wil present with hip and/or groin pain.

Bottom line: AAA and iliac artery aneurysm should at the very least be considered in older patients (and in patients with vascular disease) who present with unexplained groin/hip pain.

Acute aortic regurgitation pearls:
1. Most common cause is infective endocarditis
2. Also consider thoracic aortic dissection (chest pain plus new diastolic murmur)
3. Is the most common post-traumatic valvulopathy (chest trauma plus new diastolic murmur)
4. Presentation: diastolic decrescendo murmur at upper sternal border, may radiate to neck, hypotension, pulmonary edema
5. Treatment: get them to the OR! in the meantime, use vasopressors to support BP and afterload reduction to improve the pulmonary edema

Apathetic Hypothyroidism AKA Hypothyroidism in the Elderly

Remember that elderly do not present with classic signs and symptoms of hypothyroidism, but rather it is more common for them to have atypical presentations.

Things that make the diagnosis more difficult in the elderly are:

• The thyroid gland is often difficult to palpate.
• Symptoms like weight gain, cold intolerance, and mental and physical decline are often attributed to the normal aging process.
• Symptoms are often attributed to medications, or medications mask some of their symptoms.

Consider the diagnosis in elderly patients with:

• Arrthymias
• New onset dementia or increased “forgetfulness”
• Depression
• Failure to thrive
• Anemia
• Hyponatremia

Show References

PEARL: Any patient that in your Emergency Department with a sickle cell disease (SCD)-related diagnosis requires incentive spirometry and frequent monitoring for acute chest syndrome (ACS).

BRIEF WHY: ACS is the most common cause of hospitalization and death in patients with SCD.^1,2 

Nearly half of all patients who develop ACS are admitted for diagnoses other than ACS.  Of those not admitted with ACS, radiographic and clinical findings of ACS appeared a mean of 2.5 days after admission.² It is because of this that all patients with SCD related diagnoses at presentation, must be treated as though they are in the prodrome stage of ACS, and all require incentive spirometry to reduce the risk of progression to ACS.²

More to come... 

Show References

One of the treatment options for NYHA class III and IV pulmonary hypertension is prostanoids.  All of the prostanoid formulations have the limitations of a short half-life and a heterogeneous response to therapy.  Because the drugs need to be given by continuous infusion, patients may present to the ED due to pump failure.  Sudden cardiopulmonary collapse can occur with infusion interruption.  Here are some important points to remember regarding kinetics:

• Intravenous epoprostenol (Flolan®) has an extremely short half-life (2–3 min) and lacks stability at room temperature.  Interruption of the pump for even a short period can have drastic consequences.
• Treprostinil (Remodulin®) has theoretical advantages over epoprostenol because of its stability at room temperature, an elimination half-life of 4-6 hours (subcutaneous), and its ability to be administered by continuous subcutaneous infusion.

Depending on the location of infarct, stroke patients with dysarthria (a motor speech disorder) may exhibit the following signs and symptoms:

• "Slurred" speech
• Speaking softly or barely able to whisper
• Slow rate of speech
• Rapid rate of speech with a "mumbling" quality
• Limited tongue, lip, and jaw movement
• Abnormal intonation (rhythm) when speaking
• Changes in vocal quality ("nasal" speech or sounding "stuffy")
• Hoarseness
• Breathiness
• Drooling or poor control of saliva
• Chewing and swallowing difficulty

Airway Pressure Release Ventilation (APRV)

• As emergency physicians manage mechanically ventilated patients for longer periods of time, it is important to be familiar with newer, alternative modes of ventilation
• APRV is an open-lung ventilation strategy designed to provide oxygenation benefits while augmenting ventilation for patients with low compliance lung disease
• APRV has been described as CPAP with brief, regular, intermittent releases in airway pressure - essentially cycling between two CPAP levels
• The degree of ventilatory support is determined by the duration at each of the 2 CPAP levels and the distending pressure
• The 5 major parameters of APRV, along with suggested initial settings include:
  • P_high (high pressure): set at desired plateau pressure
  • T_high (time spent at the high pressure): 4-6 seconds
  • P_low (low pressure): 0 cm H₂O
  • T_low (time spent at the low pressure): 0.6-0.8 seconds
  • F_iO₂: 100%
• The pressure gradient between P_high and P_low, T_low, and the patient's spontaneous minute ventilation are the primary determinants of alveolar ventilation
• When using APRV, be sure to optimize intravascular volume to offset the decrease in venous return that results from prolonged positive intrathoracic pressure

Show References

Pertussis (Whooping Cough):

• Caused by B.pertussis and B.parapertussis
• Incubation period = 6 days
• Three stages:  Catarrhal (low-grade fever, rhinorrhea);  Paroxysmal (classic "whooping" cough);  Convalescent (resolution of symptoms over a ~2wk period)
• Full course of the disease = on average 6-8 weeks, although convalescent stage may last MONTHS
• Erythromycin may be effective early on, but no effect once in the paroxysmal stage
• Complications are most common in neonates and infants, and notably, the elderly
• Complications include apnea, hypoxia, pneumonia, encephalopathy, pneumothorax/pneumomediastinum (from paroxysms in the setting of severe mucus plugging)

Show References

Cushing Syndrome

The most common cause of Cushing syndrome is the use of exogenous glucocorticoids, and it is rarer to have a problem with the hypothalamic-pituitary-adrenal axis.

These patients can present with:

• proximal muscle weakness
• easy bruising
• weight gain
• hypertension
• diabetes
• impaired immune function
• infertility or menstrual irregularities

For the emergency department we need to be worried about those on chronic steroids that can not increase their native steroid production in a time of stress which will lead them to adrenal crisis.

Pearls for those with Cushing Syndrome:

• May have perforated viscous with minimal peritoneal signs
• Suspectable to fungal infections so consider adding fluconazole to those that are septic
• Give a large dose of hydrocortisone 100mg PO/IV every 8 hours if you suspect adrenal crisis.

Vicks VapoRub Toxicity

With the removal of OTC product indications for children under the age of 2 for cough and colds, more parents are turning to other agents such as Vicks VapoRub for the relief of cough and cold symptoms. Unfortunately these agents are also associated with toxicities and the potential exists for an increased number of poisonings. The primary components of these agents are:

• Camphor
• Eucalyptus Oil
• Menthol

Menthol is used to relieve symptoms of chest congestion. There is NO data to support efficacy, and paradoxically, studies have indicated increased airflow resistance with application. There is a case report of an 18 month old who developed respiratory distress after application. Symptoms associated with overdose, or inappropriate route (mucosal, oral) are:

• Aspiration
• Apnea
• Laryngoconstriction
• Nausea
• Ataxia
• Cardiac and CNS toxicity (confusion, euphoria)

Camphor in products with higher concentrations such as Campho-phenique can cause additional toxicity with effects:

• GI symptoms
• CNS: confusion, hallucinations, excitation, coma, seizures
• Apnea
• Asystole

Treatment for both is supportive.
 

Show References

• Progressive Multifocal Leukoencephalopathy (PML) is a life-threatening demyelinating condition that results from the reactivation of the polyomavirus JC. It primarily affects the immunocompromised (most commonly individuals with CD4 counts of < 200).

• Prior to the advent and widespread use of anti-retroviral therapy, 1 to 5% of those with AIDS developed PML.  HAART is now considered a mainstay of treatment, along with cessation of immunosupressant therapies.

• PML lesions typically occur bilaterally in the peri-ventricular white matter portions of the brain and do not conform to specific cerebrovascular territories. 

• Non-contrast CT and MRI may reveal PML lesions, but definitive diagnosis is made via brain biopsy. 

• Symptoms of PML include subacute neurologic deficits such as:  mental status abnormality, gait ataxia, limb ataxia, hemiparesis, monoparesis, and visual abnormalities such as diplopia and hemianopia.  Seizure occurs in up to 18% of cases.   

Antibiotic Dosing in the Critically Ill Septic Patient

• Current international guidelines recommend that intravenous antibiotics begin within one hour for those with severe sepsis and septic shock.
• Equally as important as choosing the right antimicrobial is choosing the correct dose at the right dosing schedule.
• In fact, there is evidence to suggest improved outcomes in patients given continous antimicrobial infusions (over hours) rather than intermittent bolus dosing (over minutes).
• An important cause of underdosing in critically ill patients, especially those with sepsis, is hypoalbuminemia.
• It is believed that by increasing the unbound fraction, hypoalbuminemia promotes more extensive distribution and greater renal clearance, thereby increasing the risk of underdosing.
• Take Home Point: Critically ill septic patients with hypoalbuminemia require higher dosages, or alternative regimens, to ensure appropriate antimicrobial coverage.

Show References

New Antihypertensive agent coming our way...

Well, we have nitroprusside, labetalol, nicardipine, fenoldopam, etc. Say hello to a new drug that is "reported" to be a great drug for ED patients with severe hypertension (emergencies)....Clevipidine (Cleviprex).

Clevidipine is an ultrashort acting calcium channel blocker that has been found to be a powerful antihypertensive medication.

Unique properties of the drug:

• Very short half life-quick on, quick off
• Not affected by renal/liver disease-drug is broken down into inactive metabolites by plasma esterases
• Reportedly as effective as nitroprusside and the other big guns we have for severe hypertension
• Starting dose is 1-2 mg/hour and can titrate up every 1-2 minutes.
• Contraindicated in patients with allergies to soy products and egg products

Remains to be seen if this drug will play in a role in the treatment of our severely hypertensive patients....stay tuned...

Hypovolemia is very common in the ederly for two reasons:

1. The elderly have a decreased thirst response...in other words, it takes longer for them to develop thirst in the setting of dehydration.

2. The elderly have a decreased renal vasopressin response to hypovolemia.

From a treatment standpoint, one should always assume an elderly patient is hypovolemic. Hydration is incredibly important during resuscitation of the elderly patient.

Monteggia's Fracture

• Fracture of the proximal 1/3 of the ulna with an associated radial head dislocation.
• Mechanisms of injury include direct blow, hyperpronation and hyperextension.
• Radial head is dislocated anteriorly in 60% of the cases.
• can be associated with Posterior Interosseous Nerve (PIN) palsy. 
• PIN is the deep motor branch of the radial nerve and supplies the wrist extensors except for Extensor Carpi radialis Longus.  The palsy can be delayed so be sure to document wrist extenson strength.
• Most patients will require operative repair of the ulna fracture.
• Splint the  forearm in neutral rotation with slight supination, keeping the elbow flexed at 90 degrees.

Show References

• peak age of coin ingestion is 1-3 years, 60% being males
• CXR is recommended, and if in esophagus the flat surface of coin is seen on the AP view with the edge seen on the lateral view
• if in the stomach, expectant observation (3-4 days) in the absence of abdominal pain and vomiting
• 20% of coins will lodge in the esoophagus at the level of the cricopharyngeus muscle, aortic arch, and lower esophageal sphincter
• the change in composition of pennies from cooper to zinc in recent years has increased the potential for mucosal corrosion
• all coins lodged in the proximal esophagus should be removed endoscoopically as soon as possible
• coins in the mid- to lower esophagus may be observed for 12-24 hours if asymptomatic, but should undergo endoscopy if the coin fails to pass in that time period

Show References

To feed of off Dr. Liferidge's last pearl - a few more points relevant to your Emergency Department practice:

• Lidocaine toxicity ranges between 5-7mg/kg
• Typical vial used for suture repair is 10cc of 1% lidocaine. 
• 1% = (1g/100cc) thus 100mg lidocaine in one vial
• 70 kg x 5mg/kg = 350 mg typical adult toxic dose (3+vials)
• 10 kg x 5mg/kg = 50 mg peds toxic dose (<1vial)
• Case reports of viscous lidocaine (4%) causing seizures. Very classically in pediatric cases. Cause is from oral transmucosal absorption, bypassing the large first pass effect if absorbed from the stomach.
• Classic symptoms are termed "feeling drunk" progressing to seizure. Shortly after CNS effect can have suppression of intrinsic pacemaker leading to sinus arrest, AV block, hypotension and death

Show References

Attachments

• 0907301414_BierBlock.gif (36 Kb)

• Lidocaine toxicity typically manifests as central nervous system symptoms such as tongue numbness, tinnitus, visual disturbances, seizure, and cardiovascular depression.

• The maximum dose of lidocaine without epinephrine is 5 mg/kg (4.5 mg/kg, to be exact) and 7 mg/kg for lidocaine with epinephrine.  The total maxiumum dose is 300 mg.

Internal Jugular CVC Placement and Posterior Wall Penetration

• For a variety of reasons, many critically ill ED patients require central venous access.
• Ultrasound guidance, especially with catheters placed in the internal jugular (IJ), has become standard practice in many EDs.
• Ultrasound guidance is associated with higher success rates, reduced insertion attempts, and reduced placement failures.
• Importantly, ultrasound allows you to visualize the carotid artery which often either partially overlies or even sits direclty under the IJ.
• Recent literature, however, suggests that posterior wall penetration of the IJ, even with ultrasound guidance, may be much more common than previously thought.
• Take Home Point: Even when using ultrasound, maintain strict visualization of the needle in the IJ lumen and recognize that posterior wall penetration (into the carotid) can easily occur.

Show References