case 8 - cardiac tamponade

Question 1

what is cardiac tamponade?

Answer 1

• fluid entering the pericardial sac
• acute cardiac tamponade
  
  • large volume of fluid or fluid entering sac at a fast rate that it does not give the heart time to compensate
  • emergency
• subacute caradiac tamponade / pericardial effusion
  
  • large volume that accumulates over a period of time
  • heart is able to compensate up to a certain extent

Question 2

describe the physiology of cardiac tamponade

Answer 2

3 phases

• Phase 1
  
  • fluid enters pericaridal sac, intrapericardial pressure increases, see compensatory inrease in CVP to maintain RV and LV filling
• Phase 2
  
  • as more fluid accumulates, intrapericardial pressure equalizes first with RV filling pressure
    
    • RV first because more compliant and lower filling pressure than LV
  • dec SV, inc HR to maintain CO
    
    • (poor LV filling 2/2 RV dysfunction)
• Phase 3
  
  • intrapericardial pressure equalizes with LV filling pressure
  • CO compromised - emergency

Question 3

what are s/sx of cardiac tamponade?

Answer 3

Nonspecific symptoms

• SOB, chest tightness, dizziness

Classic Findings

1) pulsus paradoxus
* exaggerated dec in systolic arterial blood pressure assoc with inspiration ( > 10 mmHg)
2) Beck Triad
* dilated neck veins, muffled heart tones, hypotension
3) Electrical alternans
* changing electrical axis cause by heart swinging freely in pericardial fluid. see low voltage too

4) PAC

• CVP = PADP = PCWP
• absent y descent in RA and PCWP tracing
  
  • atrial pressure drop as blood enters the ventricle during diastole.

Question 4

how is cardiac tamponade diagnosed?

Answer 4

Clinical Suspicion + ECHO

ECHO

• LV Chamber collapse
• RA systolic collapse
• RV early diastolic collapse
  
  • lowest ventircular pressure during diastole (intrapericardial pressure > RV chamber pressure)

Question 5

How does spontaneous respiration affect ventricular filling in cardiac tamponade? Compare normal pt to cardiac tamp pt

Answer 5

Normal Patient

• spontaneous inspiration = negative intrathorac pressure
• increases venous return to right side of heart and lungs; L side of heart has decreased filling
• result: systolic BP dec < 10 mmHg during inspiration + reflex tachy (barorceptor reflex)

Cardiac tamponade

• exaggeration of normal pressure variation
• inspiration -> RV filling shifts intraventricular septum to the LV
• decrease LV chamber size –> decrease LV filling –> decrease SV –> dec CO –> dec MAP
• result: systolic BP decrease > 10 mmHg with inspiration

Question 6

How is cardiac tamponade treated? Medical management and surgical management

Answer 6

EMERGENCY if HD UNSTABLE

• medically manage until pericardiocentesis can be done stat

Medical management:

• full, fast, tight
• Full
  
  • aggressive fluid hydration
  • increase CVP to overcome intraperdical pressure
  • SV Fixed therefore maintain SV
• Fast
  
  • promote tachycardia
  • low and fixed SV
  • CO is HR dependent. Inc HR
  • EPI, dobutamine
• Tight
  
  • increase SVR
  • maintain coronary perfusion in setting of low CO
  • norepi
• increase contracility
  
  • increase to optimize CO
  • Epi, dobuatmine

surgical = pericardiocentesis

Question 7

What are your hemodynamic goals for a cardiac tamponade patient from an anesthetic standpoint?

Answer 7

FULL, FAST, TIGHT + spont vent + inc contractility

1) Spont Vent

• AVOID PPV -> inc intrathoraci pressure -> dec venous return

2) tachycardia

• CO is rate dependent in a low fixed SV setting

3) increase preload - aggressive fluid admin

• maintain HIGH CVP to overcome intraperidcardial pressure. If not, heart chambers will collapse

4) increase SVR - maintain CPP - norepi, epi

5) inc contractility - optimize CO

Question 8

what monitors would you place, how would you induce this pt with cardiac tamponade undergoing pericardiocentesis, can you do local anesthetic?

Answer 8

Monitors

1) standard ASA
2) A-line - beat to beat monitoring
3) CVP - vasoactive admin, fapid fluid admin

Anesthesia for pericardiocentesis

• AWAKE > General
  
  • avoids deleterious hemodynamic effects of anesthetic drugs
  • avoids PPV, vasodilation, myocardial depression of anesthetic drugs
• If awake not an option
  
  • Induce with KETAMINE ONLY
    
    • maintains spont vent, inc sympathetic system (HTN, Tachy), provides great analgesia, hypnosis