Tamponade

 

Tamponade physiology

Summary

Cause of ↓cardiac output:

·      Fibrous pericardium stretches very slowly

·      Rapidly developing pericardial effusion compresses the heart

·      Reduced filling

·      Reduced output

Cause of respiratory oscillation:

·      Inspiration -> ↑VR to non-compliant RV -> ↑pressure

·      N.B. reverse occurs in mechanical ventilation

Clinical signs

·      Beck’s triad: muffled sounds + ↓BP + ↑CVP

·      Kussmaul sign: neck veins distend on inspiration (due to ↑VR)

·      Pulsus paradoxus: audible heart beat + impalpable pulse in inspiration

1.         ↑VR to RV -> septal bulge -> ↓LV compliance

2.         ↓ITP -> pulmonary venous pooling -> ↓VR to LV

ECG signs

·      ↑HR

·      Low voltage

·      Electrical alternans (↑↓QRS amplitude with oscillation in 3D space)

·      ST-T changes

Echo signs

·      Pericardium:

o  Effusion

·      Cardiac chambers: collapsed

o  Diastole before systole

o  Right before left

o  Atria before ventricles

·      Inflow vessels:

o  Dilated IVC

o  Diastolic flow reversal (hepatic + pulmonary)

·      Inspiratory changes:

o  Septal bounce R -> L

o  ↓LVOT VTI

 

Anaesthesia for tamponade:

Problems

·      Rate-dependent output

·      Pre-load dependent output

·      Intolerance of positive pressure ventilation

·      Associated disaster: trauma, dissection

·      Comorbidities: IHD, cardiomyopathy, cancer, inflammatory

·      Full stomach

Goals

·      Full: big IV + pumpset + CSL

·      Fast: adrenaline infusion + boluses

·      Tightish: metaraminol infusion

·      Sinus rhythm

Induction options

·      Pericardiocentesis -> wait -> normal induction

·      Sevo + nitrous + spont vent until drainage

·      Ket + sux + apnoea until drainage