Effects of Prone and Reverse Trendelenburg Positioning on Ocular Parameters

Abstract

: Prolonged prone positioning increases IOP, choroid layer thickness, and optic nerve diameter independent of anesthetics and intravenous fluid infusion and 4 degrees of table inclination (15 cm of head to foot vertical disparity) may not attenuate these effects.

Kurzversion S2e-Leitlinie – „Lagerungstherapie und Frühmobilisation zur Prophylaxe oder Therapie von pulmonalen Funktionsstörungen“

“…In prospektiven randomisierten Studien wurde bei Patienten in Bauchlage im operativen Bereich der intraokulare Druck (IOP) vor, während und nach der Lagerungsmaßnahme gemessen [28,34,46] …”

Positioning patients for spine surgery: Avoiding uncommon position-related complications

“…Choroid layer thickness showed mild improvement (reduction) with 4° Trendelenburg position. The authors related the increase in the prone diameter of retrobulbar optic nerve to a dependent increase in subarachnoid fluid or venous congestion rather than intrinsic swelling [147] . AION AION is associated with spine surgery and is the most common cause of ION associated with open heart surgery [138] .…”

“…The authors found no difference in hematocrit levels or blood pressure values or the use vasopressor between cases and controls [138] . Grant et al [147] investigated the effect of prolonged prone positioning on ocular parameters in 10 volunteers. The authors demonstrated a progressive increase in the IOP, choroid layer thickness and retrobulbar diameter of the optic nerve in the prone position compared to supine position over 5 h. The peak increase for most parameters was at 5 h in the prone position.…”

“…Arterial infarction of the retrobulbar optic nerve due to ischemia is primarily due to decreased oxygen delivery. Decreased oxygen delivery may be due to a decrease in arterial perfusion pressure, increased resistance to blood flow or a reduction in oxygen carrying capacity [147] . The prone position may contribute to increased orbital venous pressure or venous congestion which may contribute to a decrease in arterial perfusion pressure and venous infarct respectively.…”

“…Usually ION presents as selective AION or PION, presumably due to different predisposing factors and differences in the blood supply to those portions of the nerve [141] . Hypertension, diabetes, obesity, hypotension, anemia, prone position, smoking, vascular disease, increased blood viscosity and abnormal anatomy have been associated with ION and perioperative visual loss [139,140,[142][143][144][145][146][147] . Anemia, hypotension, peripheral vascular disease and blood transfusion were associated with ION after spine surgery [90,92] .…”