Perioperative IV fluid therapies include crystalloids and colloids. Crystalloids are water-based solutions, usually with low-molecular-weight salts (vs. ions), whereas colloids contain high-molecular-weight proteins or glucose polymers. Another type of infusing material, called vesicants, has greater potential for substantial cellular injury. Vesicants include radiocontrast dyes, pressor agents, and chemotherapy solutions. In theory, colloid solutions may increase extravascular fluid content after infiltration by drawing fluid out of the cells, whereas any hypotonic solution may lead to cellular rupture after fluid absorption. Dyes act more like hypotonic solutions and include methylene blue and indocyanine green. Infiltration with these dyes may result in severe skin discoloration, but this effect is not permanent. The duration of discoloration is dependent on the rate of dye (fluid) reabsorption from the extracellular space, usually 12 to 24 hours. Hyaluronidase injected in multiple sites around the infiltration site has been used to treat mannitol infiltration.

Before anesthetic induction, initial palpation of the IV site is recommended. If fluids (or medications) are administered by syringe extravascularly, they
may elicit high pressure on injection, causing pain in awake patients. Relying on a free-flowing IV may lead to false positives, particularly in the elderly, for whom loose skin may allow easy infiltration. For catheters that are not located in an extremity, such as central lines, be mindful of which vein the catheter is expected to enter because infiltration will depend on its position in the body; extravasated fluid may leak into the arm, chest wall, or neck. Positive aspiration of blood must be achieved, providing the IV was placed in the major central vein. Transducing the catheter should be done to confirm venous placement of a central line.

If the extremity is exposed during surgery, continuous monitoring of the IV site for edema or blanching are necessary. Jewelry such as rings should be removed before surgery, especially for arms that are tucked in (placed along the body and covered with drapes) and arms in which the IV catheter has been placed. However, the frequent practice of tucking in arms requires careful IV monitoring. Should the IV stop flowing intraoperatively, full inspection of the IV site must be made. Facilitation of a sluggish IV by using “pressure bags” should not be done until the site is properly inspected for signs of possible extravascular infiltration.