PAC vs TOE in Shock

OVERVIEW

• there are many differences between the use of TOE vs PAC in the management of shock
• indications depend on specific information desired and local expertise
• potential information obtained must be weighed against risk
• if standard precautions used mortality and morbidity with either techniques is rare

PRACTICAL ASPECTS

TOE

• inserted orally
• can only be inserted in anaesthetised patients
• useful in unstable patients (diagnosis in unstable aortic dissection patients)
• interpretation often very subjective
• not all data continuous (only one view @ a time)
• expensive equipment and maintenance
• may distract from other important aspects of management

PAC

• invasive (all risks of CVL insertion)
• patient can be awake
• takes longer to insert than TOE

INFORMATION PROVIDED

TOE

• systolic function (fractional shortening of LV, EF, fractional area of contraction)
• SV
• Q
• pressures (PAP in presence of TR, RSVP +LSVP in presence of VSD, PASP, LAP, LVEDP)
• valve areas
• calculation of regurgitant volumes and fractions
• intracardiac shunt fraction
• pericardial disease (tamponade)

PAC

• Q (thermodilution technique applied or continuous monitoring)
• PAP
• SvO2
• RAP
• derived values = SVR, SVRI, SV, SVI, PVR, PVRI, Left Ventricular Stroke Work Index

DATA INTERPRETATION

TOE – data interpretation affected by

• user inexperience (steep learning curve)

PAC – thermodilution accuracy affected by

• cardiac shunt
• TR and MR
• variation in temperature from a variety of sources
• IPPV

SAFETY AND COMPLICATIONS

TOE

• oesophageal ulceration +/- perforation
• sore throat
• airway obstruction
• displacement of ETT
• orophayrngeal/dental trauma
• cardiac aneurysm rupture
• sympathetic stimulation
• infection

PAC

• arrhythma (heart block)
• infection
• knotting
• pulmonary infarction
• hypotension
• hypoxia
• PA rupture
• air embolism
• in large trials not shown to produce benefit
• limited sensitivity for detecting myocardial ischaemia
• PAWP only intermittent measurement