All practice questions

A $27$-year-old male is brought to the emergency department $2$ hours after sustaining thermal injuries in an industrial flash fire. He is awake and alert. His airway is intact with no evidence of inhalational injury. Vital signs show a blood pressure of $115/75$ mm Hg, a heart rate of $108/min$, and a respiratory rate of $18/min$. Physical examination reveals deep partial-thickness burns over his entire anterior chest and abdomen, as well as his entire left upper extremity (circumferential). He weighs $80$ kg. Peripheral intravenous access is established.

Using the traditional Parkland formula ($4$ mL/kg/$\%$ total body surface area), what is the appropriate intravenous fluid administration rate (in mL/hr) for the remainder of the first $8$ hours following the injury?

An unresponsive 52-year-old male is transported to the triage area by paramedics after being found in a mechanic's garage. According to bystanders, he had been drinking an unidentified liquid from a jug. His temperature is 36.5°C (97.7°F), blood pressure is 150/92 mm Hg, pulse is 108/min, and respirations are 24/min and deep. He responds only to painful stimuli.

Laboratory studies show the following:
Sodium: $139$ mEq/L
Potassium: $4.8$ mEq/L
Chloride: $104$ mEq/L
Bicarbonate: $10$ mEq/L
Blood urea nitrogen (BUN): $14$ mg/dL
Creatinine: $1.8$ mg/dL
Glucose: $90$ mg/dL
Measured serum osmolality: $318$ mOsm/kg $H_2O$

Arterial blood gas (room air):
pH: $7.22$
$PCO_2$: $23$ mm Hg
$PO_2$: $98$ mm Hg

Based on the provided laboratory data, what is the patient's serum osmolar gap?

A 42-year-old woman is transported to the emergency department after a grease fire erupted at the commercial kitchen where she works. The incident occurred exactly 3 hours before her arrival at the trauma center. She weighs $80 \text{ kg}$. On primary survey, her airway is patent, breathing is spontaneous but tachypneic, and hemodynamics are stable. Physical examination reveals deep partial-thickness and full-thickness burns involving her entire anterior trunk, her entire right arm, and the anterior surface of her right lower extremity. The remainder of her skin is uninjured. Using the traditional Parkland formula ($4 \text{ mL/kg/\%TBSA}$), at what rate (in $\text{mL/hour}$) should the initial intravenous crystalloid infusion be set to deliver the appropriate fluid volume over the remainder of the first 8-hour window?

A 68-year-old female is admitted to the hospital from an assisted living facility due to five days of severe, voluminous watery diarrhea. On presentation, she is lethargic with dry mucous membranes and delayed capillary refill. Her blood pressure is 88/54 mm Hg and her heart rate is 115/min. Laboratory studies are obtained:

Assuming a normal anion gap of 12 mEq/L and a normal serum bicarbonate of 24 mEq/L, what is this patient's delta-delta ratio ($\frac{\Delta AG}{\Delta HCO_3^-}$)?

A 34-year-old woman arrives at the regional burn center via ambulance after being rescued from a residential house fire. She sustained deep partial-thickness and full-thickness thermal burns. Physical examination reveals that her entire right leg and her entire right arm are burned. Her uninjured skin is intact. The patient weighs $75 \text{ kg}$. The incident occurred exactly $2 \text{ hours}$ prior to her arrival at the hospital. Two large-bore intravenous lines are established.

Using the traditional Parkland formula ($4 \text{ mL/kg/}\% \text{TBSA}$), what should be the initial intravenous fluid infusion rate (in $\text{mL/hr}$) to administer the required volume over the remainder of the first 8 hours post-injury?

A 45-year-old man is evaluated in the intensive care unit for worsening kidney function. Three days ago, he was admitted with severe sepsis secondary to right lower lobe pneumonia and required vasopressor support for 48 hours. His blood pressure is now stable off vasopressors. Urine output over the last 12 hours has been 250 mL.

Laboratory studies are obtained:

What is the patient's fractional excretion of sodium ($Fe_{Na}$) expressed as a percentage?

Paramedics bring a 52-year-old unhoused man to the emergency department after he was found unresponsive in an alleyway during the winter. He has a known history of alcohol use disorder. On examination, he is obtunded and tachypneic.

Vital signs include a heart rate of $105/\text{min}$, blood pressure of $115/75 \text{ mmHg}$, and respiratory rate of $24/\text{min}$.

Laboratory studies reveal the following:

Arterial blood gas on room air shows a pH of $7.25$, $\text{pCO}_2$ of $28 \text{ mmHg}$, and $\text{pO}_2$ of $95 \text{ mmHg}$.

Based on the laboratory results provided, what is this patient's calculated serum osmolar gap in $\text{mOsm/kg}$?

A 32-year-old male is brought to the emergency department after being rescued from a structure fire. He sustained deep partial-thickness and full-thickness thermal burns involving his entire anterior chest and abdomen, his entire right lower extremity, and his entire right upper extremity. The patient currently weighs $80\text{ kg}$. The injury occurred exactly $2\text{ hours}$ prior to his arrival at the emergency department. Two large-bore peripheral intravenous lines are placed. Following current Advanced Trauma Life Support (ATLS) guidelines for adult thermal burns (which recommend $2\text{ mL/kg/\%TBSA}$), what should be the initial continuous intravenous infusion rate of lactated Ringer solution in $\text{mL/hr}$?

A 35-year-old woman with a history of systemic lupus erythematosus presents to the clinic with progressive muscle weakness and fatigue over the past 2 weeks. She denies any recent illnesses, diarrhea, or vomiting. Current medications include hydroxychloroquine. Vital signs are within normal limits. Laboratory testing reveals the following:

What is this patient's calculated urine anion gap?

A 68-year-old man is evaluated in the intensive care unit for decreased urine output. Three days ago, he was admitted with severe community-acquired pneumonia and septic shock, which required aggressive intravenous fluid resuscitation and continuous norepinephrine infusion. Over the past 24 hours, his urine output has decreased to 250 mL. His blood pressure is 105/65 mm Hg, pulse is 98/min, and respirations are 18/min. Physical examination reveals warm extremities and trace bilateral pitting edema. Laboratory studies are obtained:

Based on these findings, what is this patient's calculated fractional excretion of sodium (in percentage)?

During a routine follow-up appointment, a 38-year-old female reports a one-month history of progressive muscle weakness and fatigue. Her past medical history is significant for Sjögren syndrome and multiple episodes of calcium phosphate nephrolithiasis. Vital signs show a blood pressure of 118/76 mm Hg and a heart rate of 84/min. Physical examination reveals dry oral mucosa and 4/5 motor strength in the proximal muscles of the upper and lower extremities.

Laboratory evaluation reveals the following:

Based on these findings, what is this patient's calculated urine anion gap in mEq/L?

A 48-year-old man is brought to the emergency department by emergency medical services after his neighbor found him unresponsive in his garage. An open, empty container of automotive antifreeze was found nearby. On examination, he is deeply lethargic and responds only to painful stimuli. His vital signs show a blood pressure of $110/70 \text{ mmHg}$, heart rate of $105/\text{min}$, and respiratory rate of $24/\text{min}$.

Laboratory testing reveals the following:

Based on the laboratory findings, what is the patient's calculated serum osmolar gap?

A 35-year-old man is brought to the emergency department after being rescued from a burning building. The fire department successfully extracted him from the fire 2 hours ago. On examination, the patient is hemodynamically stable and weighs 90 kg ($198.4$ lbs). He has severe deep partial-thickness and full-thickness burns involving his entire anterior trunk, his entire right arm, and the anterior aspect of his left leg. The remainder of his skin, including his face, neck, and posterior surfaces, is unaffected. Large-bore intravenous access is obtained. Using the traditional Parkland formula ($4$ mL/kg/% total body surface area), at what rate (in mL/hr) should intravenous lactated Ringer solution be administered to this patient initially?

A $28$-year-old woman with a history of type 1 diabetes mellitus presents to the hospital after $4$ days of worsening abdominal pain, severe nausea, and frequent episodes of nonbilious vomiting. She has missed several doses of her basal insulin due to her inability to tolerate oral intake. On arrival, her blood pressure is $98/62 \text{ mm Hg}$, and her pulse is $115/\text{min}$. Physical examination reveals significantly dry mucous membranes, decreased skin turgor, and diffuse mild abdominal tenderness without rebound or guarding.

Laboratory values are as follows:

Serum sodium: $138 \text{ mEq/L}$
Serum potassium: $4.8 \text{ mEq/L}$
Serum chloride: $92 \text{ mEq/L}$
Serum bicarbonate: $14 \text{ mEq/L}$
Arterial pH: $7.28$
Arterial $PaCO_2$: $29 \text{ mm Hg}$

Assume a normal baseline anion gap of $12 \text{ mEq/L}$.

What is the patient's calculated corrected bicarbonate level in $\text{mEq/L}$?

A 42-year-old man is brought to the emergency department after being rescued from a house fire. On primary survey, his airway is patent, breathing is spontaneous, and breath sounds are equal bilaterally. Vital signs are temperature $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), pulse $115/\text{min}$, respirations $22/\text{min}$, and blood pressure $110/70\text{ mmHg}$. Physical examination reveals deep, blistered, weeping skin as well as charred, leathery eschar over his entire head and neck, his entire anterior trunk, his entire left arm, and the anterior surface of his left leg. The skin of his entire right arm is erythematous, dry, and painful to touch but lacks blisters. Based on the Rule of Nines, what is the calculated total body surface area (TBSA) percentage that should be used to guide his initial fluid resuscitation?

A 68-year-old man is evaluated in the hospital for decreased urine output. He was admitted 3 days ago for severe gastroenteritis and has had poor oral intake. His blood pressure is $96/60 \text{ mm Hg}$ and heart rate is $112/\text{min}$. Physical examination reveals dry oral mucosa and delayed capillary refill. Laboratory studies show:

Based on these laboratory findings, what is the patient's calculated fractional excretion of sodium (expressed as a percentage)?

A 42-year-old man is brought to the emergency department by ambulance after being found unresponsive in his garage. His wife reports that he has a history of major depressive disorder and recently lost his job. On physical examination, he is unarousable. Blood pressure is 115/75 mm Hg, pulse is 112/min, and respirations are 24/min and deep.

Laboratory studies show:
Serum sodium: 140 mEq/L
Serum potassium: 4.6 mEq/L
Serum chloride: 105 mEq/L
Serum bicarbonate: 10 mEq/L
Blood urea nitrogen (BUN): 28 mg/dL
Serum creatinine: 1.8 mg/dL
Serum glucose: 108 mg/dL
Measured serum osmolality: 320 mOsm/kg H2O

What is this patient's serum osmolar gap in mOsm/kg H2O?

A $35$-year-old woman with a history of Sjögren syndrome comes to the clinic due to progressive generalized weakness and fatigue for the past month. Her blood pressure is $110/70$ mm Hg and her physical examination is unremarkable except for dry oral mucosa.

Laboratory studies show:
- Serum sodium: $140$ mEq/L
- Serum potassium: $2.8$ mEq/L
- Serum chloride: $115$ mEq/L
- Serum bicarbonate: $13$ mEq/L
- Urine sodium: $45$ mEq/L
- Urine potassium: $25$ mEq/L
- Urine chloride: $40$ mEq/L

The patient's serum anion gap is calculated to be $12$ mEq/L (normal: $10-14$ mEq/L), indicating a normal anion gap metabolic acidosis. To help determine whether the acidosis is due to renal or gastrointestinal etiology, what is this patient's calculated urine anion gap (in mEq/L)?

A $45$-year-old man with a history of severe alcohol use disorder is brought to the emergency department after $3$ days of intractable vomiting and generalized weakness. On physical examination, he appears lethargic and has dry mucous membranes with decreased skin turgor. Vital signs show a blood pressure of $95/60 \text{ mmHg}$, heart rate of $118/\text{min}$, and respiratory rate of $24/\text{min}$. Laboratory evaluation reveals the following:

- Serum sodium: $138 \text{ mEq/L}$
- Serum potassium: $3.2 \text{ mEq/L}$
- Serum chloride: $86 \text{ mEq/L}$
- Serum bicarbonate: $10 \text{ mEq/L}$
- Blood urea nitrogen: $42 \text{ mg/dL}$
- Serum creatinine: $1.9 \text{ mg/dL}$
- Plasma beta-hydroxybutyrate: elevated

Based on the provided laboratory values, the physician suspects a mixed acid-base disorder and decides to calculate the delta-delta (corrected) bicarbonate. Assuming a normal anion gap of $12 \text{ mEq/L}$, what is the patient's calculated delta-delta bicarbonate level?

During morning rounds in the medical intensive care unit, a physician evaluates a patient admitted for severe hypovolemia secondary to intractable diarrhea.

The patient, a $55$-year-old male, reports four days of unremitting watery stools. Intravenous fluid resuscitation is planned but has not yet been initiated. Vital signs show a blood pressure of $90/60\text{ mm Hg}$ and a heart rate of $110/\text{min}$. Physical examination is notable for poor skin turgor, delayed capillary refill, and dry oral mucosa. Laboratory analysis of blood and urine samples obtained simultaneously reveals the following values:

Based on these findings, what is the patient's calculated fractional excretion of sodium (in percent)?