DIP Episode 270 - USMLE Step 2CK Rapid Review Series 43 (and upcoming 2CK Course 11/6-7)

Source / episode info

• Episode: 270
• Title: Divine Intervention Episode 270 – USMLE Step 2 CK Rapid Review Series 43 (and upcoming 2 CK Course 11/6-7).
• Published: 2020-10-22
• Source: Episode page

One-liner

This episode provides high-yield rapid review on critical care emergencies, including differentiating heat stroke causes, managing malignant hypothermia (MH), distinguishing neuroleptic malignant syndrome (NMS) from serotonin syndrome (SS), and treating various hypertensive crises.

High-yield summary

• Heat Stroke Management: For physical exertion-related heat stroke, use ice water immersion. For drug/medication-induced heat stroke (e.g., acetaminophen overdose, sympathomimetics), use evaporative cooling mechanisms (fans).
• Malignant Hypothermia (MH): This is an autosomal dominant disorder caused by mutations in the ryanodine receptor (a calcium channel) that triggers during exposure to volatile anesthetics or succinylcholine. Treatment involves stopping the trigger and administering dantrolene.
• NMS vs SS: NMS is associated with dopamine blockers, decreased deep tendon reflexes (DT Rs), and no myoclonus. Serotonin Syndrome (SS) is caused by multiple serotonergic agents, and is characterized by increased DT Rs and myoclonus.
• Hypertensive Emergencies: In the setting of MAOI use and tyramine ingestion, administer a reversible, non-selective alpha blocker like phentolamine. For CCF exacerbation, nitrates (e.g., nitroglycerin) are preferred vasodilators.
• Myoglobinuria/Rhabdomyolysis: If urine shows 4+ blood but few red blood cells per high power field, suspect myoglobinuria, which can cause acute tubular necrosis (ATN).

Learning objectives

• Differentiate the clinical presentation and management of various hyperthermic emergencies (heat stroke).
• Identify the triggers and first-line antidotes for malignant hypothermia.
• Distinguish between neuroleptic malignant syndrome, serotonin syndrome, and other causes of altered mental status/rigidity.
• Select appropriate antihypertensive agents based on the clinical setting (e.g., pregnancy, CCF exacerbation).
• Interpret abnormal urine findings suggestive of myoglobinuria or albuminocytologic dissociation.

Board exam buzzwords

Rapid review table

Board-speak -> diagnosis

Differential diagnosis / distinguishing features

Serotonin Syndrome vs NMS

Hypertensive Crisis Management

Management pearls

• Serotonin Syndrome (SS): First-line treatment is a Benzodiazepine (e.g., lorazepam) to control agitation and muscle hyperactivity. Only use cyproheptadine if benzodiazepines are unavailable.
• Malignant Hypothermia (MH): The definitive antidote is Dantrolene. Always stabilize the myocardium first with IV Calcium and Glucose before administering Dantrolene.
• Tyramine Crisis: Use a reversible, non-selective alpha blocker like Phentolamine. This rapidly counteracts the massive catecholamine release from MAOI inhibition.
• Heat Stroke Cooling: For physical exertion, use ice water immersion. For drug/medication toxicity (e.g., acetaminophen), use evaporative cooling (fans).

Don't miss

Integration & clinical reasoning

• Pharmacology Integration: Understanding drug metabolism pathways (MAO Is, CYP enzymes) is crucial for recognizing hypertensive crises (tyramine). The concept of reversible alpha blockade (phentolamine) applies across multiple acute settings.
• Pathophysiology Integration: MH and NMS both involve severe hypermetabolic states leading to muscle breakdown; the key difference lies in the underlying trigger (genetic/anesthetic vs. neurotransmitter imbalance).
• Clinical Reasoning: When presented with a constellation of symptoms (e.g., fever, rigidity, altered mental status), always generate a differential diagnosis that includes NMS, MH, and SS before settling on one answer.

OMM / COMLEX integration

• Standard emergency management takes priority over OMT in unstable patients (e.g., severe hypertension, altered mental status).
• For MH/NMS: Focus on immediate stabilization and drug administration; supportive care is paramount.
• OMT Contraindications: Do not delay life-saving interventions for traditional acupressure points or non-pharmacological therapies when the patient is acutely unstable (e.g., severe HTN, altered mental status).

Concept connections / cross-references

• No explicit cross-references.

High-yield association table

Key terms glossary

Study optimization

Question pattern recognition

• Pattern: High fever + Rigidity + Anesthesia exposure -> MH: Always suspect MH in this setting; the first step is to stop the anesthetic agent and administer Dantrolene.
• Pattern: MAOI use + Aged cheese/Tyramine -> Hypertensive Crisis: The immediate treatment must be a non-selective alpha blocker (Phentolamine). Never give an ACE inhibitor or ARB in this setting due to potential for worsening crisis.
• Pattern: Confusion + Muscle rigidity + Dopamine antagonist exposure -> NMS: Remember the "double negative": low DT Rs and no myoclonus helps distinguish it from SS.

Test yourself

Common mistakes to avoid

Common traps