Cardiac Critical Care Study Notes

Cardiac Critical Care Study Notes

Asymptomatic Bradycardia

• Usually no treatment required unless symptomatic or hemodynamically unstable.

• Monitor closely.

Cardiac Tamponade

• Definition: Fluid accumulation in the pericardial sac → ↓ preload → ↓ stroke volume (SV) → ↓ cardiac output (CO).

Electrolyte Effects on EKG

• Hypokalemia: U waves.

• Hyperkalemia: Peaked T waves.

• Hypocalcemia: Prolonged QT.

• Hypercalcemia: Shortened QT.

Normal Hemodynamics

• BP: 90–120 / 60–80 mmHg

• HR: 60–100 bpm

• CO: 4–8 L/min

• SVR: 800–1,200 dynes/sec/cm⁵

• PVR: 37–250 dynes/sec/cm⁵

• SvO₂: 60–80%

• PAP: Systolic 15–30 mmHg / Diastolic 4–12 mmHg

• CVP: 2–6 mmHg

Ventricular Fibrillation

• Produces ineffective stroke → ↓ SV and CO → no perfusion.

Right Ventricular (RV) Failure after RV MI

• RV failure → ↓ LV preload → ↓ SV and CO.

• Treatment: Careful fluid loading (e.g., hypertonic saline, mannitol, albumin). Avoid excessive preload reduction.

Intra-Aortic Balloon Pump (IABP)

• Optimal timing:

  • Inflation during diastole (after AV closure).

  • Deflation just before systole (QRS).

• Functions:

  • Decrease afterload.

  • Increase coronary perfusion.

• Waveforms:

  • Unassisted Systolic

  • Unassisted End-Systolic

  • Assisted Diastolic

  • Assisted End-Diastolic

  • Unassisted End-Diastolic

MI Lead Localization

• Septal: V1, V2

• Anterior: V3, V4

• Lateral: I, aVL, V5, V6

• Inferior: II, III, aVF

Endocarditis

• Inflammation of the inner lining of the heart.

Thrombi

• Most common location: legs (DVT → risk of PE).

Drugs Quick Reference

Antiarrhythmics

• Amiodarone – Antiarrhythmic.

• Lidocaine (2 g/500 mL) – Antiarrhythmic.

Calcium Channel Blockers

• Nicardipine/Cardene – Vasodilator, acts on periphery.

• Diltiazem/Cardizem – Acts on both heart + periphery.

Inotropes & Vasodilators

• Dobutamine (500 mg/250 mL) – Inotrope + dilator (β1/β2 agonist).

• Milrinone/Primacor (50 mg/250 mL) – Inotrope + vasodilator (PDE inhibitor, useful in PHTN & RV dysfunction).

Vasopressors

• Dopamine (400 mg/250 mL) – Dose-dependent:

  • Low: Dopamine agonist

  • 5–10 mcg/kg/min: β agonist

  • High: α agonist

• Epinephrine (5 mg/250 mL) – β agonist (low), α agonist (high).

• Norepinephrine/Levophed (4 mg/250 mL) – α agonist (main), β agonist (high dose).

• Phenylephrine/Neosynephrine (20 mg/250 mL) – Pure α agonist.

• Vasopressin (20 mg/100 mL) – V1 receptor agonist.

Vasodilators

• Nitroprusside/Nipride (50–100 mg/250 mL) – Arterial vasodilator.

• Nitroglycerin (25 mg/250 mL) – Venodilator (at higher doses also arterial).

Beta Blocker

• Esmolol (2500 mg/250 mL) – Short-acting β blocker.

Sedative

• Dexmedetomidine/Precedex (200 mcg/50 mL or 400 mcg/100 mL) – Sedative, α2 agonist.

Critical Care Study Notes

Hemodynamic Normals

• CVP (RA preload): 2–6 mmHg | 5–10 cm H₂O

• SVR (afterload, left heart): 900–1200 dynes/sec/cm⁵

• PAWP (LA preload): 8–12 mmHg

• MAP: 60–80 mmHg

• CO: 4–8 L/min

• CI: 2.8–3.6 L/min/m²

• PAP: Systolic 25–30 / Diastolic 6–12 mmHg

• SvO₂: 70–75% (mixed venous O₂)

• PVR (afterload, right heart): 80–180 dynes/sec/cm⁵

Hemodynamic Treatments

• CVP >8: diuretics, nitroglycerin, morphine, lisinopril, losartan

• CVP <2: fluids, blood, blood products

• PAWP >12: diuretics, nitroprusside

• PAWP <8: fluids, blood, blood products

• SVR >1200: nitroprusside, nitroglycerin, hydralazine, lisinopril, losartan, IABP

• SVR <900: phenylephrine, norepinephrine, epinephrine, vasopressin

• PVR >180: epoprostenol (Flolan)

• EF <40%: milrinone, dobutamine, digoxin, AICD

• Elevated contractility: metoprolol, amlodipine

• Special scenarios:

  • CVP >8 & PAWP <12 → nitroglycerin, nitroprusside, epoprostenol

  • MAP <60 + HR >100 → phenylephrine, vasopressin

  • MAP <60 + HR <100 → norepinephrine, dopamine

  • MAP >80 + HR >100 → nitroglycerin, nitroprusside, nicardipine, metoprolol

  • CO <4 + MAP <60 → epinephrine

  • CO <4 + MAP <60 + HR <60 → epinephrine, dopamine

  • CO <4 + MAP >60 → dobutamine, epinephrine, dopamine, milrinone

• Formula for CO: HR × SV

Receptors & Drugs

• α1 Receptors (vessels): vasoconstriction

• β1 Receptors (heart): ↑ HR & contractility

• β2 Receptors (lungs): bronchodilation

Key Drugs:

• Pure α1 agonist → phenylephrine

• Vasoconstrictors → phenylephrine, vasopressin

• Inoconstrictors (inotrope + vasoconstrictor) → norepinephrine, dopamine, epinephrine

• β1 meds → epi, norepi, dobutamine, dopamine

• β2 meds → albuterol, dobutamine (mild), milrinone

Notes:

• Nitroglycerin contraindicated in RV MI

• Check thiocyanate levels with nitroprusside

• Norepinephrine may cause abdominal pain (gut ischemia)

Neuro & ICP

• Normal ICP: 0–15 mmHg

• Normal CPP: MAP – ICP

• Goal: ICP <20, adequate CPP

• Early ↑ ICP: HA, ↓ LOC

• Late ↑ ICP: Pupil changes, Cushing’s triad (↑ BP/wide pulse pressure, ↓ HR, irregular respirations)

• Positioning: HOB ↑, head midline, neutral

• Monitoring: transduce at tragus, no pressure bag, drain OR monitor (not both)

Heart Disease & Angina

• Stable Angina: fixed stenosis, exertional, T-wave inversion → rest/NTG

• Unstable Angina: thrombus, frequent/severe, ST elevation → NTG, revascularization

• Prinzmetal’s (Variant) Angina: vasospasm, transient ST elevation → Ca²⁺ blockers (amlodipine)

MI EKG Locations

• Inferior: II, III, aVF

• Septal: V1–V2

• Anterior: V2–V4

• Lateral: I, aVL, V5–V6

• RV MI: V3R–V4R

MI Tx

• Gold standard → PCI (door-to-balloon <90 min)

• If no cath lab → tPA (within 6 hrs)

• Meds: MONA-B (morphine, O₂, NTG, ASA, β-blocker), diuretics

Heart Failure

• RV Failure: JVD, edema, ascites, ↑ CVP, hepatomegaly

• LV Failure: pulmonary edema, dyspnea, crackles, ↑ PAWP

• First compensatory mechanism: SNS → ↑ HR

• Later mechanism: RAAS → Na/H₂O retention → dilutional hyponatremia

Arrhythmias

• 1° AVB: prolonged PR, benign

• 2° AVB Mobitz I: PR lengthens until drop → atropine

• 2° AVB Mobitz II: fixed PR, dropped QRS → atropine/pacing

• 3° AVB: no association P-QRS, HR <40 → pacemaker

• SVT: adenosine, β-blockers, vagal, correct lytes

• VT: check pulse → cardioversion/defibrillation, epi

• Torsades: magnesium

• VF: defibrillation, epi

Respiratory & Ventilation

• PEEP: 5–10 cm H₂O

• Risks → ↓ CO (↑ intrathoracic pressure), barotrauma

• Mechanical ventilation effects: ↓ venous return → ↓ CO, ↓ BP

Chest Tubes

• Tidaling = normal

• Bubbling = air leak

• Problems: tracheal deviation, ↑ dyspnea, O₂ sat <90%, drainage >70 mL/hr → call MD

• Falls out: cover w/ 3-sided dressing

• Disconnected: place in sterile water

Renal & Pulmonary

• Pulmonary edema (renal failure): HTN, JVD, frothy sputum, tachypnea, hypoxia

  • Tx: dialysis, morphine, NTG, furosemide

• Anemia in renal failure: Epoetin alfa

Acid-Base

• Resp Acidosis: pH <7.35, CO₂ >45 (hypoventilation, COPD, OD)

• Resp Alkalosis: pH >7.45, CO₂ <35 (hyperventilation)

• Metabolic Acidosis: pH <7.35, HCO₃ <22 (DKA, sepsis, shock)

• Metabolic Alkalosis: pH >7.45, HCO₃ >26 (vomiting, NG suction, diuretics)

Compensation:

• Respiratory → adjust RR (CO₂)

• Metabolic → adjust HCO₃

• Complete comp: pH normal, both abnormal

• Partial comp: pH abnormal, both abnormal

SIRS (Systemic Inflammatory Response Syndrome)

• S/S: tachycardia, tachypnea, fever

• Tx: treat underlying cause, fluids, antibiotics if sepsis suspected