The head down Trendelenburg position is used to improve exposure in abdominal and laparoscopic surgeries, robotic surgeries, during central line placement,
and as an option to help treat hypotension.
Hypovolemia can be unrecognized in the lithotomy and Trendelenburg position as MAP can appear normal.
In cardiac patients, Trendelenburg may increase myocardial work due to increased CVP, SV, and CO - patients may not be able to tolerate - may actually decrease CO as they move to a worse position on the Franks-Starling curve.
If the patient has peripheral vascular disease there is an increased risk of ischemia.
Complications
Improperly placed shoulder devices can injure the brachial plexus – rarely used
Arms can slip off armboards, hyper extend and cause injury to the brachial plexus
POVL due to increase in ocular venous pressures and simultaneous decrease in ocular perfusion pressure
If lithotomy is added to the position
- Increased risk for nerve injuries
- Increased preload
- Increased risk of peripheral ischemia
Anesthetic considerations
- Use of non-sliding mattress to prevent patient sliding off table
- Increased ICP due to transmission of venous pressures through the valveless jugular system
- Decreased cerebral blood flow due to limited inflow r/t venous congestion
- Facial and airway edema with potential for post-operative airway obstruction – verify air leak prior to extubation
- Risk of ETT displacement into the R main bronchus
- Increased ETCO2, respiratory acidosis
- Decreased FRC, VC, and compliance due to cephalad displaced abdominal content
- Increased Peak airway pressure and ventilation-perfusion mismatch (shunt with under ventilation compared to perfusion)
- Pulmonary congestion and edema
- Normotensive patients compensate for increased CVP and PAP with vasodilation and decreased HR due to stimulation of the baroreceptor reflex
- Hypotensive patients may not be able to respond in the same manner
- Risk of aspiration, risk of regurgitation of acidic fluids onto facial skin