Educational Objective:

Diagnose giardiasis.

Key Point:

Suspect giardiasis in a patient with known risk factors presenting with chronic diarrhea and malabsorption. The diagnosis can be confirmed with fecal immunoassays given their high sensitivity and specificity.

Explanation:

The patient’s presentation is consistent with giardiasis. Although Giardia trophozoites and cysts may be identified in stool samples, the fecal elimination of the organisms is intermittent and multiple samples may be required to confirm a diagnosis. Instead, fecal immunoassays are the diagnostic method of choice given their high sensitivity and specificity.

Giardiasis usually presents as chronic diarrhea that does not respond to conventional antibiotics. Flatulence, steatorrhea, abdominal cramps, and foul-smelling stools are common symptoms.

The patient has multiple (frequently missed) risk factors for giardiasis, including travel to an endemic country, close contact with children, and having sex with other men.

A stool culture will be negative. A fecal fat excretion test result might be abnormal, but it will not confirm the diagnosis.

Metronidazole is the treatment of choice for this infection and it is curative in most instances.

Reference:

Cope JR, et al. Infectious diseases relating to travel (chapter 3). In: Centers for Disease Control and Prevention (CDC). CDC Yellow Book 2018. Accessed July 22, 2018.

Educational Objective:

Identify the endoscopic findings associated with high rates of mortality.

Key Point:

Various endoscopic findings during active bleeding are associated with different rates of mortality. Active bleeding carries an 11% mortality risk.

Explanation:

Of the options given, active bleeding portends the greatest risk for recurrent upper GI bleeding and mortality from peptic ulcer disease. Active bleeding on endoscopy is associated with an 11% mortality rate and a 55% risk of recurrent bleeding from the same site. A nonbleeding, visible vessel is the next worst prognostic factor, with a 43% risk of recurrent bleeding and an 11% mortality rate. A clean-based ulcer and a flat, pigmented spot have less than a 10% likelihood of recurrent bleeding.

Reference:

Kovacs TO, Jensen DM. Gastrointestinal hemorrhage. In: Goldman L, Schafer AI. Goldman-Cecil Medicine. 2016:879-884.e2.

Educational Objective:

Recall causes of otitis externa.

Key Point:

Otitis externa is commonly caused by an infection. P aeruginosa, staphylococci epidermidis, and Staphylococcus aureus are the most common pathogens.

Explanation:

This patient is experiencing otitis externa most likely due to infection. In general, otitis externa is defined as any inflammation (due to inflection, trauma, or dermatitis) of the external ear canal with or without involvement of the tympanic membrane. In otitis externa caused by infection, P aeruginosa and S aureus are the most common etiologic organisms followed by various aerobic and anaerobic bacteria, followed by fungi (only 10% of cases). If fungi are involved, then approximately 90% are due to Aspergillus, and the remaining ones are caused by Candida infection. Swimming, diving, using cotton swabs, living in humid countries, and the presence of foreign bodies in the ear all lead to desquamated skin and/or retained moisture in the ear canal. This process creates a favorable culture medium for bacteria and fungi to invade the external ear canal.

References:

Osguthorpe JD, Nielsen DR. Otitis externa: review and clinical update. Am Fam Physician. 2006;74(9):1510-1516.

Rosenfeld RM et al: Clinical practice guideline: acute otitis externa. Otolaryngol Head Neck Surg. 150(1 Suppl):S1-S24, 2014

Roberts JR. Roberts and Hedges' Clinical Procedures in Emergency Medicine. 6th ed., 2014.

Educational Objective:

Discuss advanced life support in a hypothermic drowning victim in cardiac arrest.

Key Point:

For hypothermic drowning victims, leaders in the fields of wilderness and emergency medicine recommend providing full regular resuscitation while simultaneously rewarming the patient.

Explanation:

The American Heart Association guidelines only briefly address the topics of drowning and accidental hypothermia, leaving the details to experts in these fields.

Clinical management does not differ between fresh and salt water drowning. Isotonic crystalloid is the preferred resuscitation fluid for all drowning victims.

Pearls: If it appears that the patient may later benefit from therapeutic hypothermia, then the body should not be rewarmed beyond 32°C to 34°C (90°F to 93°F), which is the goal temperature of therapeutic hypothermia.

References:

Sempsrott J, et al. Drowning and Submersion Injuries (Chapter 69). Auerbach's Wilderness Medicine 7^th ed. 2017. Part 10 1-28.

Richards DB. Drowning. (Chapter 137) In: Walls R, et al. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed., 2018: 1801-1804e.

Educational Objective:

Examine various types of hip dislocations.

Key Point:

Hip dislocations are labeled by the relationship of the femoral head to the acetabulum and are typically described as anterior, posterior, central, or inferior. Posterior dislocations (femoral head posterior to acetabulum) account for 80%-90% of cases.

Explanation:

Posterior dislocations are almost always the result of motor vehicle collisions. A seated vehicle occupant typically has the hip adducted, flexed, and internally rotated at the time of impact.

Anterior dislocations are seen in 10% to 15% of patients and are subdivided into obturator dislocation (femoral head is medially rotated toward the obturator foramen) or pubic dislocations (the head is laterally rotated toward the pubis). Central dislocations, which occur in 2% to 4% of cases, are not true dislocations because the entire femoral head is forced centrally through a comminuted fracture of the acetabulum. Inferior dislocation (luxatio erecta) of the hip is a rare condition that occurs almost exclusively in children younger than 7 years of age. A fracture–dislocation includes an associated fracture of the acetabulum or femoral head.

Reference:

Walls R, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed., 2017.

A second degree AV block Mobitz Type 1 (Wenckebach) is recognized on an ECG by its prolongation of the PR interval and shortening of the RR interval.

The key to understanding this rhythm is to realize that 1) the PP interval remains (relatively) constant and that 2) the greatest increase of the PR interval occurs between the first and second beat of any one Wenckebach cycle. If, for example, the first PR interval is normal, and the second one is lengthened by for example, 10% (these are fictitious numbers), then that first RR interval of a given Wenckebach cycle will be 10% longer than the patient’s normal RR interval. This first abnormal RR interval is the standard-setting RR interval within a given cycle of Wenckebach. The next PR interval might add another 5% of PR lengthening to the already present 10% lengthening, but then the RR interval between the second and third beat will only be 5% longer (not 15%!)  than the normal RR interval and, relatively speaking, shorter than the first abnormal RR interval, which was 10% longer than the normal RR interval. In other words, each successive QRS adds another increment of tardiness after the P-wave, but each time, a smaller tardiness is added, which paradoxically results in shorter rather than longer RR intervals (there are exceptions, but this is the general rule).

Progressive PR interval prolongation occurs before the blocked sinus impulse. Shortening of the PR interval occurs after the blocked sinus impulse, provided that the P wave is conducted to the ventricle.

References:

ECG. Wenckebach Phenomenon.  Life in the Fast Lane.

Barold SS, Herweg B. Second-degree atrioventricular block revisited. Herzschrittmacherther Elektrophysiol. Dec 2012;23(4):296-304.

The board of nursing

Advanced practice registered nursing (APRN) practice is typically defined by the state nurse practice act and governed by the state board of nursing, but other laws and regulations may affect practice, and other boards may play a role. For instance, in some states nurse-midwives are regulated by a board of midwifery or public health. In other states, both the board of medicine and the board of nursing regulate nursing practice.

Brudzinski’s maneuver

A stiff neck or nuchal rigidity is a sign of meningitis and intracranial hemorrhage. Brudzinski’s sign may also be present when neck stiffness is assessed. Flexion of the hips and knees when flexing the neck is a positive Brudzinski’s sign for meningeal irritation.

Aortic stenosis

One of the most frequent pathological systolic murmurs is due to aortic stenosis. The murmur of aortic stenosis is typically a mid-systolic ejection murmur, heard best over the “aortic area” or right second intercostal space, with radiation into the right neck. It has a harsh quality and may be associated with a palpably slow rise of the carotid upstroke. Additional heart sounds, such as an S4, may be heard secondary to hypertrophy of the left ventricle, which is caused by the greatly increased work required to pump blood through the stenotic valve.