Questions 09/20/2012

Thoracic and Environmental

Question 1

You are preparing to intubate an obese patient (body weight 127 kg) with a history of sleep apnea. What would be the approximate desaturation time (SaO2 < 90%) for this patient after paralysis if he was fully preoxygenated with an FiO2 of 1:a) 3 minutesb) 5 minutesc) 7 minutesd) 9 minutese) 11 minutes

Answer 1

• Preoxygenation • 100% oxygen for 3 minutes of

normal tidal volume in healthy adult results in 8 minutes before desaturation to less than 90%

• Time to desaturation less in children, obese adults, late-term pregnancy women, and patients with significant comorbidity

Answer 1

Question 2

You are managing a trauma patient with a flail chest who is in respiratory distress. Indications for mechanical ventilation would include:a) Respiratory rate > 25/minb) Respiratory rate < 12/minc) PaO2 < 70 mm Hg at FiO2 > 0.5d) PaCO2 > 55 Hg at FiO2 > 0.5e) Alveolar-arterial oxygen gradient > 350

Answer 2

• Flail chest• 3 or more ribs fractured at 2 points• Indications for mechanical ventilation– Respiratory failure (RR >35/min or < 8/min,

PaO2 < 60 mm Hg at FiO2 0.5; PaCO2 > 55 mm Hg at FiO2 0.5, alveolar arterial oxygen gradient > 450)

– Clinical evidence of severe shock– Associated head injury with lack of airway

control or need to ventilate– Severe associated injury requiring surgery

Question 3

What is the MOST common finding in a patient with a brown recluse spider bite?a) Severe itchingb) Local tissue necrosisc) Severe muscle crampsd) Anaphylaxis

Answer 3

• Brown recluse spider bite• Characterized by local necrosis• Treatment includes:– Local wound care– Consider dapsone (helpful for local effects)

if presentation within 48 hours.• Watch for methemoglobinemia and hemolysis in

patients with G6PD deficiency

• Black widow spider bite characterized by muscle cramping

Question 4

A 45-year-old male has been found to have a pneumonia. In determining whether he meets admission criteria to the hospital you calculate the patients Pneumonia Severity Index score. Which of the following co-morbid conditions contributes most to the PSI score. with food allergies will outgrow their allergies over timea) Renal diseaseb) Cerebrovascular diseasec) Congestive heart failured) Liver diseasee) Neoplastic disease

Answer 4

Question 5

A 32-year-old worker is brought by ambulance from a synthetic fiber manufacturing plant complaining of weakness and dizziness after being overcome by fumes from the recovery tanks. Shortly after arrival, he becomes unconscious. You are concerned about toxic exposure. As you remove the patient’s clothing you note the smell of almonds. After intubation and administration of 100% oxygen, you: a) Crush a pearl of amyl nitrite and hold it in the intake

valve of the Ambu bagb) Administer methylene bluec) Begin chelation therapyd) Consult hyperbaricse) Consult nephrology for possible hemodialysis

Answer 5

• Cyanide poisoning• Binds Fe3+ in cytochrome ultimately

preventing ATP formation• Antidotes– Cyanokit (Hydroxocobalomin 5 gm IV)

• Binds cyanide forming cyanocobalamin (B12)

– Cyanide Antidote Kit (sodium thiosulfate, sodium nitrite, amyl nitrite)• Nitrites form hethemoglobin which binds cyanide• Sodium thiosulfate acts as sulfur donor to enzyme

responsible for conversion of cyanide to thiocyanate which is renally excreted

Question 6

In which patient is an ED thoracotomy MOST indicated?a) A 76-year-old male who was the unrestrained driver in a 70

mph motor vehicle crash and was found pulseless at the scene

b) A 25-year-old female with a gunshot wound to the right chest that upon arrival to the ED is found to have a blood pressure of 40 mmHg by palpation and no breath sounds on the right

c) A 40-year-old male with a stab wound to the left chest who lost all vital signs 3 minutes prior to arriving at the ED and has received bilateral needle chest decompressions

d) A 27-year-old construction worker with an impaled fence post in his abdomen, a blood pressure of 90/60 mm Hg, and fluid in Morison’s pouch revealed by ultrasound

Answer 6

• Thoracotomy• Indications– Penetrating Traumatic Cardiac Arrest

• Cardiac arrest at any point with initial signs of life in the field

• Blood pressure < 50 mm Hg systolic after fluid resuscitation

• Severe shock with clinical signs of cardiac tamponade

– Blunt Trauma• Cardiac arrest in the emergency department

– Miscellaneous• Suspected air embolus

Question 7

Choose the correct statement concerning treatment of snakebites:a) Snakebites should be treated prophylactically with an

antibiotic selected for its Gram-positive activity, particularly against staphylococcal species

b) The amount of antivenin given is based on the severity of the symptoms

c) The dose of antivenin given to children is weight basedd) Of the calculated dose of antivenin, 25-50% should be

infiltrated into the local wound of the bite and the rest given intravenously

e) Copperhead bites always require antivenin administration

Answer 7

• Snakebite• Elapidae = coral snakes– Death most commonly from respiratory

paralysis– Other symptoms include tremors,

dysarthria, diplopia, miosis, ptosis, dyspnea and seizures

• Crotalidae = pit vipers (rattlesnakes, cottonmouths, copperheads)– Crofab antivenom if symptomatic

Question 8

While scaling Mt. McKinley, a34-year-old triathlete develops headache, anorexia, nausea, vomiting, and fatigue. The base camp physician will know that:a) Cerebral edema is a possible consequence secondary to

hypocapnia or hypoxiab) These symptoms will likely resolve without treatment as

she ascends higherc) This condition is best treated with acetazolamided) Prior physical conditioning should have been effective in

preventing this illnesse) Because of the estrogen-protective effect, this patient

will have less severe symptoms than her male counterpart

Answer 8

• Acute Mountain Sickness• Incidence varies with rate of ascent• Mild cases usually self limited and do not

require treatment (discontinue ascent, rest)• Moderate cases administer acetazolamide,

aspirin, acetaminophen for headache; prochlorperazine for nausea; supplemental oxygen in available

• Descend for persistent or severe cases (add dexamethasone)

Question 9

In discharging patients treated in the ED for asthma, you must remember that:a) Airway inflammation and edema usually take 6-12

hours to resolveb) Patients receiving systemic corticosteroids should

continue this medication for at least 10 daysc) The relapse rate of those discharged is less than 10%d) It is not the responsibility of the emergency physician

to initiate controller medicationse) Those who require ED treatment are likely to have

less asthma management skills than the average asthmatic patient

Answer 9

• Asthma• Inflammation takes 3-4 days to

resolve• Steroids should not be prescribed for

more than 5 days• More than 10% of asthmatic patients

treated in the ED return with a relapse

Question 10

A 5-month-old previously healthy male infant presents to the ED with cough and dyspnea for 2 days and a temperature of 38.4 C (101.1 F). There is no family history of asthma. His respiratory rate is 48/min and he has bilateral expiratory wheezing and subcostal retractions. His oxygen saturation is 93 % on room air. Which of the following is the most common cause of his illness?a) Adenovirusb) M. pneumoniaec) Parainfluenza virusd) RSVe) Staphylococcus aureus

Answer 10

• Bronchiolitis• Inflammation of the small airways in children less

than 2 years old• RSV most common cause, believed to be

associated in up to 70% of cases• Factors that mandate hospitalization include:

– Age less than 3 months– Gestational age less than 34 weeks– Ill appearance– Hypoxemia (SaO2 95%)– Tachypnea (>70/min)– Significant atelectasis on chest xray

Answer 10Mild Moderate Severe

Feeding Normal Less Poor

SaO2 in room air

≥95% 92–94% <92%

Respiratory rate

< 60 60-70 > 70

Retractions None/minimal Intercostal Substernal

Accessory muscle use

None None Neck or abdominal

Wheeze None/minimal Moderate expiratory

Severe inspiratory/expiratory

Air exchange Goode, equal BS

Localized, decreased BS

Multiple areas of decreased breath sounds

Answer 10