Correct Answer: A Section: (none)

Explanation:

Atrial fibrillation is the most common sustained clinical arrhythmia. It occurs in approximately 4% of the population over the age of 60. It is diagnosed by the presence of irregularly irregular QRS complexes on an ECG with an absence of P waves. The QRS complex is most commonly narrow, as this is a supraventricular arrhythmia. Wide QRS complexes can occur if there is an underlying conduction abnormality, such as Wolff-Parkinson-White syndrome or a bundle branch block. Saw-tooth Pwaves occur in atrial flutter, another atrial arrhythmia that may present similarly to atrial fibrillation but which is less common. The saw-tooth P waves, or flutter waves, are representative of an atrial rate typically in the range of 300350/minute.

Not infrequently, atrial flutter will lead to atrial fibrillation. Q waves in II, III, and aVF would be seen if there had been a previous inferior MI. Peaked T waves are seen in certain conditions, such as hyperkalemia, but are not routinely associated with atrial fibrillation. Atrial fibrillation may be precipitated by both cardiac and noncardiac conditions. Among the noncardiac conditions are metabolic abnormalities, which include hyperthyroidism. Of the tests listed, a suppressed TSH level, consistent with hyperthyroidism, would be most likely to be causative of atrial fibrillation. Troponin may be elevated in acute myocardial ischemia. Atrial fibrillation can occur following a MI, particularly when complicated by CHF. This is not consistent with the clinical scenario presented. Renal disease and diabetes may contribute to some of the conditions that can predispose to the development of atrial fibrillation, such as metabolic derangements or CAD. Acute and chronic pulmonary disease may also precipitate atrial fibrillation. In the setting of a man who is otherwise healthy and without significant medical history, new-onset atrial fibrillation would be less likely to be the initial presentation of diabetes, renal failure, or pulmonary disease than hyperthyroidism. For this reason, choice A is the single best answer of those provided.

Correct Answer: B Section: (none)

Explanation:

The clinical scenario described is classic for an acute MI. The patient has multiple risk factors, including smoking, hypertension, and elevated cholesterol. His symptoms of crushing chest pain radiating to the left arm is commonly seen in this setting. Often the first electrocardiographic sign of acute ischemia is the development of hyperacute T waves. The ECG will usually show S-T segment elevations in the area of the involved occluded vessel, with reciprocal S-T segment depressions in uninvolved areas. This can be followed by the eventual resolution of S-T segment abnormalities and the development of T wave inversions and Q waves. Diffuse P-R depressions are often the initial manifestation of pericarditis, a less common cause of acute chest pain. This often progresses to diffuse S-T segment elevations, the presence of which helps to distinguish pericarditis from the focal S-T elevations more classically associated with a thrombosed coronary artery. Q waves would be unlikely to occur within 1 hour of the onset of symptoms. In this clinical setting, a normal ECG, while possible, would be less likely to occur.

Ventricular arrhythmias, both tachycardia and fibrillation, are recognized complications of acute MI. The presence of ventricular fibrillation or pulseless ventricular tachycardia should lead to the primary "ABCD" survey, as outlined in the American Heart Association's ACLS protocols. The mnemonic stands for airway, breathing, circulation, and defibrillation. Epinephrine, lidocaine, or amiodarone are reserved for the setting where defibrillation is ineffective. Synchronized cardioversion would be used in efforts to convert a patient's rhythm in the setting of a stable tachycardia.

Correct Answer: E Section: (none)

Explanation:

The most common cause of otitis media in children is pneumococcus (S. pneumoniae). This is also the most common cause of sinusitis and pneumonia. Otitis media is usually seen in conjunction with an upper respiratory tract infection. Pressure from extensive use of antimicrobials has resulted in a dramatic increase in penicillin resistance in pneumococcus. Amoxicillin remains the recommended initial antibiotic of choice for the treatment of otitis media in children. In an effort to reduce the incidence of antibiotic resistance, and because of the high spontaneous cure rate of otitis media, many authorities are advocating withholding antimicrobial treatment unless symptoms persist for several days in spite of symptomatic treatment.

Correct Answer: E Section: (none)

Explanation:

This case demonstrates a classic presentationfor delirium. Delirium can present with many symptoms, including aggressiveness, hostility, memory impairment, psychotic symptoms (especially visual hallucinations), and overall uncooperativeness, such as pulling out IVs and getting out of bed. While these symptoms are common in delirious patients, they are not specific for delirium and can be seen in many psychiatric illnesses, including dementias, psychotic disorders, substance use disorders, personality disorders, and others.

The hallmark of delirium is a fluctuating level of consciousness over time, ranging from sedation to agitation. Diphenhydramine can be sedating but, due to its anticholinergic side effects, can also worsen delirium and cause urinary retention and constipation, especially in the elderly. Anticholinesterase inhibitors such as donepezil may be indicated for mild-tomoderate dementias, especially Alzheimer dementia. It is not indicated for the treatment of delirium and it would be difficult to diagnose a dementing illness in the context of a delirious state. Giving benzodiazepines such as lorazepam may be useful for agitation caused by a delirium, but they can also disinhibit a patient and cause further agitation, especially in older individuals. A benzodiazepine would be the preferred treatment of alcohol withdrawal delirium (delirium tremens [DTs]), however. A low dose of antipsychotic would be the best choice to decrease the agitation in a delirious patient. While a high-potency medication such as haloperidol can be used, it is more likely to cause extrapyramidal side effects than a second-generation (or atypical) antipsychotic such as risperidone.

Correct Answer: D Section: (none)

Explanation:

The mnemonic "ABCDE" is often used to remember some of the attributes of skin lesions that would make them more suspicious for being malignancies. "A" is for asymmetry; "B" for border that is irregular or indistinct from the surrounding skin; "C" for color such as dark black or variations in colors within the same lesion; "D" for diameter greater than 6 mm, or larger than the size of a pencil eraser; "E" for elevation of lesion with surface irregularity. Of the choices in question 56, the presence of a diameter of greater than 6 mm would be considered a higher-risk attribute. Primary skin malignancies are divided into three major categories--basal cell carcinoma, squamous cell carcinoma, and melanoma. Basal cell carcinomas may grow large and be locally destructive, but they have the lowest metastatic potential of the three types of skin cancer. Basal cell carcinomas are more common in persons with fair complexions but they occur in all skin types and colors. Squamous carcinomas of the skin have a metastatic potential greater than basal cell carcinomas and less than malignant melanomas. Squamous carcinomas most commonly occur in sun-exposed areas but are also associated with other etiologies, such as human papilloma virus (HPV), and can occur anywhere on the body. Malignant melanoma has the highest metastatic potential of the primary skin malignancies. Melanoma can occur in any skin type, but is more common in skin types I and II (fair skin). Obtaining a tissue sample for pathologic studies of suspicious skin lesions is critical for diagnosis and planning of appropriate treatment of melanoma. The thickness of the lesion is an important factor in these decisions. Therefore, shave biopsy would be inappropriate for the evaluation of a pigmented lesion. Complete excisional biopsy would be preferable, or, when that is not possible, full-thickness punch biopsy is an acceptable alternative. While sun exposure is an important risk factor for all types of skin cancers, for melanomas there is some evidence that intermittent, intense sun exposure and sunburning is more of a risk than cumulative sun exposure. Actinic keratoses are sun-induced skin lesions that are considered risks for the development of squamous carcinomas. They can be treated with local destructive methods, such as cryosurgery or the topical chemotherapeutic agent 5-fluorouracil. Protection of susceptible skin from excessive sun exposure from childhood is important in reducing the risk of developing skin cancer. Precautions such as wearing broad-brimmed hats, long sleeved clothing, and avoidance of intense midday sunlight are helpful. Using chemical sunscreens with SPF of greater than 15 with frequent reapplication is also beneficial. Even "waterproof" sunscreens need to be reapplied after bathing or swimming. Awet cotton T-shirt provides very little, if any, protection from ultraviolet light exposure. Both the UV-A and UV-B rays play roles in skin damage from the sun and it is important to use sun protection products, which block both types of rays. Sun tanning booths are also considered risks for the induction of skin damage and skin cancer as they expose skin to potentially damaging ultraviolet rays.