CARDIOLOGY
PEA with a narrow QRS suggests which category of causes?
Mechanical/obstructive causes (Ts)
WHY:
Narrow QRS = electrical system is intact
The heart wants to beat, but can’t fill or eject
That points to mechanical problems, not metabolic ones
Think:
Tamponade
Tension pneumothorax
Massive PE
Narrow QRS PEA = Ts
Wide QRS PEA = Hs
First signs of pediatric respiratory failure (not distress).
Decreased respiratory rate / altered mental status
WHY:
Distress = fast, working hard
Failure = tired
Once RR drops → arrest is next
A drug class that competitively blocks beta receptors.
Beta blockers
WHY:
They compete at beta receptor sites
Block sympathetic response
Supine hypotensive syndrome is relieved by this intervention.
Left lateral uterine displacement
WHY:
The uterus compresses the IVC
decreased venous return
Roll the uterus → BP improves
Most reliable sign of hypovolemia in infants.
Delayed capillary refill
WHY:
BP is preserved until late
Perfusion tells the truth
Inferior STEMI + hypotension + clear lungs = avoid this medication.
Nitroglycerin (RV infarct preload dependence)
WHY:
Inferior MI often involves the right ventricle
RV is preload dependent
Nitro ↓ preload → BP tanks → patient crashes
BVM with good chest rise but falling SpO₂ suggests failure at this level.
Alveolar diffusion/shunting
WHY:
Air is moving
Oxygen isn’t crossing
Think pneumonia, ARDS, pulmonary edema
Medication that increases preload but worsens pulmonary edema.
IV fluids
WHY:
Edema = fluid overload
More fluid creates a worse gas exchange
Painful third-trimester bleeding suggests this diagnosis.
Placental abruption
WHY:
Pain = muscle tearing
Previa is painless
Why is hypotension a late sign in children?
Strong compensatory mechanisms
WHY:
Kids have:
Strong sympathetic response
Elastic vessels
Ability to increase HR and SV
They compensate HARD… until they suddenly crash
Irregularly irregular rhythm, no P waves, RVR at 160 bpm: priority if hypotensive?
Synchronized cardioversion
WHY:
Hypotension = unstable
You do not slow them down first
You fix the rhythm NOW
Sudden hypoxia + hypotension post-intubation: rule out this immediately.
Tension pneumothorax
WHY:
Positive pressure can convert simple pneumo to tensionpneumo
Kills venous return, creating hypotension
Epinephrine improves anaphylaxis primarily through which receptor?
Alpha 1 Vasoconstriction
WHY:
Restores BP
Reduces edema
Keeps the airway open
This most commonly causes postpartum hemorrhage.
Uterine atony
WHY:
The uterus fails to clamp down
Bleeds freely
Primary cause of cardiac arrest in pediatrics.
Respiratory failure
WHY:
Most pediatric arrests are asphyxial, not cardiac
Sequence:
Hypoxia
Bradycardia
Asystole
Tall R waves and ST depression in V1–V3 indicate infarction of which wall?
Posterior wall MI
WHY:
Posterior MI hides
What you see is mirror-image changes
ST depression anteriorly = ST elevation posteriorly
Why do infants desaturate faster during apnea?
Low Functional Residual Capacity + high O₂ demand
WHY:
Less oxygen reserve
Higher metabolic rate
No buffer
Which sedative causes hypotension by venodilation?
Benzodiazepines
WHY:
Venodilation
decreased preload
Especially dangerous in shock
Seizure prevention drug in preeclampsia.
Magnesium sulfate
WHY:
Stabilizes the neuromuscular junction
Prevents seizures (not BP control)
Bradycardia + poor perfusion in infant—treat with what first?
Ventilation with oxygen
WHY:
Pediatric bradycardia is almost always hypoxia-driven
Oxygenation often corrects the heart rate
Drugs come after ventilation
Osborn waves appear in this condition and worsen with continued exposure.
Hypothermia
WHY:
Osborn (J) waves = classic hypothermia finding
Colder = bigger waves
Dead giveaway ECG finding
End-tidal CO₂ drops suddenly during CPR: what does this indicate?
Loss of perfusion / impending arrest
WHY:
EtCO₂ reflects cardiac output
Drop = circulation just died
Medication absorption is delayed most by which physiologic state?
Shock (poor perfusion)
WHY:
Poor perfusion
The drug doesn’t reach circulation
A patient in active labor develops shoulder dystocia. After performing the McRoberts maneuver, the infant’s shoulder remains impacted. What is the next appropriate intervention?
Suprapubic pressure
WHY:
Dislodges the anterior shoulder
Fundal pressure is dangerous
Croup vs epiglottitis: which gets humidified O₂ only?
Epiglottitis
WHY:
Epiglottitis = critically unstable airway
Agitation can cause:
Sudden complete obstruction
Do NOT visualize the airway
Do NOT force interventions
Keep calm, give O₂, transport