Tamponade

Tamponade pathophysiology

Summary	· Fibrous pericardium stretches very slowly · Rapidly developing pericardial effusion compresses the heart · Reduced filling · Reduced output · General anaesthesia is often lethal, especially if IPPV
Clinical signs	· Beck’s triad: muffled sounds + distended neck veins + hypotension · Kussmaul sign: neck veins distend on inspiration (spont vent) · Pulsus paradoxus = audible heart beat + impalpable pulse in inspiration 1. Normal: ↓ITP -> pulmonary venous pooling -> ↓VR to LV 2. Abnormal: ↓ITP -> ↑VR to RV -> septal bulge -> ↓LV compliance
ECG signs	· ↑HR · Low voltage · Electrical alternans (↑↓QRS amplitude with oscillation in space) · ST-T changes
Echo signs	· Pericardium: o Effusion o ±Thickening · Cardiac chamber collapse o Systole before diastole o Right before left o Atria before ventricles · Inflow vessels: o Dilation o Diastolic flow reversal · Inspiratory changes: o Low output on inspiration (i.e. pulsus paradoxus) o Diastolic septal bounce

Problems

· Rate-dependent output

· Pre-load dependent output

· Intolerance of positive pressure ventilation

· Intolerance of supine positioning

· Associated disaster: trauma, dissection

· Comorbidities: IHD, cardiomyopathy, cancer, inflammatory

· Full stomach

Goals

· Prevent CVS collapse at induction

o Percutaneous drainage prior

o Minimise intrathoracic pressure

o Full, fast, tight, sinus rhythm

· Prevent rebound hypertension after drainage

o Sympatholytics/vasodilators prepared

· Prevent aspiration

· Prevent awareness

Approach

· Assess for compromise

o Toxic appearance

o Large swing on A-line

o Echo signs

· If compromised: needle pericardiocentesis pre-induction

o Must avoid pneumopericardium

o Beware sedation -> upper airway obstruction -> big breath

· If not compromised: careful induction of some sort

· Consider having the patient prepped and draped