9 free Paramedic practice questions: Advanced Differential Diagnosis

The vomiting that began yesterday: Vomiting is genuinely on the thyroid storm list, so it reads as a point in favor. It sits on the sepsis list too, and a finding both candidates predict cannot separate them no matter how well you know it belongs to one.

The temperature of 103.6°F: The temperature is the most objectively abnormal number on the page, and the biggest number is a magnet when you are asked what matters most. A fever of 103.6°F is why both conditions made your list in the first place, which is precisely why it cannot narrow it.

The confusion and agitation at home: Altered mentation appears on both sides of this differential, and it is the finding most often treated as decisive because it is the most alarming thing in the room.

Establishing intravenous access and applying the pads: Establishing IV access and applying pads is preparatory care that touches neither conduction nor contractility; it can look like wasted time on an unstable-looking tachycardia, but neither action changes this patient's hemodynamics.

Obtaining a 12-lead ECG before choosing a treatment: Acquiring a 12-lead on a patient running at 170 sounds like a delay that risks deterioration, but this is exactly the step that sorts a genuinely narrow rhythm from VT before a drug gets chosen, and getting one on an alert patient with a pressure of 116/72 carries no risk itself.

Consulting medical control about the rhythm interpretation: Consulting medical control about a borderline-width, ambiguous rhythm is appropriate use of online backup for an uncertain call; it doesn't touch this patient's blood pressure or conduction, so it isn't the action that risks collapse.

Prolonged expiration with diffuse wheezing: points toward an airflow obstruction problem like COPD or asthma, not toward fluid backing up behind a failing left ventricle.

Absent breath sounds over one side of the chest: points toward a pleural-space problem like a pneumothorax, not toward the bilateral basilar crackles and venous congestion seen in cardiogenic pulmonary edema.

Deep, rapid respirations with clear lung sounds: points toward a metabolic process like diabetic ketoacidosis, not toward the fluid-filled alveoli that produce crackles in cardiogenic pulmonary edema.

Hypoglycemia: causes altered mental status through glucose-starved neurons, usually with diaphoresis, tachycardia, and agitation. A blood glucose level of 96 mg/dL is normal, so the metabolic cause this option names is already excluded by the number in the question.

Postictal state: A postictal state follows a seizure with gradual return of consciousness, confusion, and often diaphoresis, but breathing and pupils are usually near normal. A respiratory rate of 6 with pupils fixed at 2 mm goes well beyond that, and points instead to a respiratory depressant.

Acute ischemic stroke: can look like this: a pontine lesion damages both pupillary and respiratory centers together, producing bilateral pinpoint pupils with severe respiratory depression, mimicking this picture, but that severity of stroke usually shows a clear focal onset or known vascular risk, and here a reversible toxic cause fits the unwitnessed collapse better.

Acute viral illness: An acute viral illness wouldn't produce identical symptoms starting around the same time in three unrelated people sharing only the same home environment, especially with a fuel-burning furnace as the shared exposure.

Food-borne illness: doesn't fit a household headache-and-nausea pattern tied to a heating appliance during heating season. Nothing here points to a shared meal as the source.

Simple asphyxiant exposure: A simple asphyxiant exposure doesn't explain this specific symptom pattern the way carbon monoxide does, and the shared-exposure pattern combined with a fuel-burning appliance points specifically toward carbon monoxide until proven otherwise.

Loss of sensation over the affected cheek: Loss of sensation over the cheek points toward trigeminal nerve (CN V) involvement, a sensory cranial nerve problem. Bell palsy and stroke both present as motor facial weakness with sensation intact, so a sensory deficit answers a different question than the one the droop is asking.

Drooping that spares the forehead: the finding that should support Bell palsy, since forehead sparing is the classic teaching point in facial droop cases. Here it actually argues the opposite: sparing means the frontalis still has its bilateral cortical input, which is the stroke pattern, not the peripheral nerve palsy pattern of Bell palsy.

Tongue deviation toward the affected side: reflects a hypoglossal nerve (CN XII) lesion, often from a brainstem stroke, and nothing in this presentation mentions tongue involvement. It points to a separate cranial nerve and a separate differential from the facial droop described.

Weakness confined to one side of the body: matches the left-sided findings here, but that pattern shows up in both Todd paralysis and a hemispheric stroke, so it can't distinguish which one caused this child's deficit.

Deficits that were maximal at the onset: Deficits that are maximal at the onset describe how an acute ischemic stroke typically presents: the deficit is worst the instant the vessel occludes, then stays flat rather than improving. Todd paralysis works the opposite way, appearing after the seizure and easing over time, so onset severity argues for stroke, not for this child's postictal weakness.

A blood glucose level within normal limits: already 88 mg/dL in this stem, rules out hypoglycemia as the cause of the altered mental status and weakness. It says nothing about whether the deficit is resolving or stroke-related, so it can't be the finding that specifically points to Todd paralysis.

Progression of the underlying dementia: Dementia itself is a slow, progressive decline in memory and function that plays out over months to years, and this patient's baseline was described as stable and conversational. An overnight jump into hallucinations and a fluctuating level of consciousness is far too abrupt for dementia progression, which doesn't explain the acute onset here.

A new primary psychiatric disorder: can produce hallucinations, but it typically appears with intact attention and a steady, not fluctuating, level of consciousness, and no prior psychiatric history is given. The drifting off mid-sentence points to an organic process, and psychiatric causes are only considered after medical ones are ruled out.

Normal age-related memory decline: looks like mild, stable forgetfulness that doesn't include hallucinations or a change in level of consciousness. This patient's acute hallucinations and drifting arousal are well outside that pattern and reflect a new pathologic process, not aging.

Loss of circulating volume from internal bleeding: doesn't fit warm, flushed skin: blood loss produces pale, cool, clammy skin from vasoconstriction instead.

Reduced ventricular contractility lowering cardiac output: Reduced ventricular contractility would typically produce cool, clammy skin and signs of backward failure, not the warm, flushed, vasodilated picture seen here.

Obstruction of blood flow leaving the heart: would produce distended neck veins or other obstructive signs, not flat neck veins with warm, flushed skin.