Fluid Restriction in Robotic Surgery: Why Anti-Hydration Prevents Airway Edema

The strategy of anti-hydration during surgical procedures is implemented with the rationale of minimizing complications such as facial, orbital, and airway edema. This approach is crucial as clinical swelling of the face and upper airway is accompanied by venous stasis in the head and neck. By minimizing fluid administration, the likelihood of successful extubation is increased since significant upper airway edema can complicate anesthetic emergence and extubation. Furthermore, by limiting fluid intake, the potential for postoperative re-intubation is decreased. 

In specific surgical contexts, such as prostatectomy, anti-hydration has the added benefit of decreasing the amount of urine in the pelvis, facilitating the surgical procedure. It's suggested that for a patient undergoing prostatectomy, fluid intake should be limited to less than 1 liter until the completion of critical surgical anastomoses.

The general goal of anti-hydration is to maintain optimal intravascular volume and cardiac filling while restricting intraoperative fluids to under 2 liters, or even less, depending on the individual case. This is particularly important if the patient has undergone a bowel prep preoperatively, which may necessitate slightly more fluid to compensate for preoperative fluid losses. If the patient experiences hypotension, colloids can be supplemented to support blood pressure without significantly increasing fluid volume within the body.

Towards the end of the surgery, as the surgeon is closing, there is more flexibility to administer additional fluids as necessary. This staged approach to fluid management allows for the critical balance between ensuring adequate perfusion and minimizing the risks associated with excessive fluid administration, such as edema and potential respiratory complications.