To the Editor: Over the last 15 yr of practice, we have seen several cases of adverse outcomes after extravascular extravasation of fluids or drugs intended for intravenous infusion. Especially bad outcomes result from extravasation of hypertonic glucose solutions, calcium, and vasopressors Figure 1. An equally frustrating problem is the malpositioned intravenous line used for rapid-sequence induction of anesthesia, with subsequent failure to secure the airway rapidly. The difficulty of detecting extravascularly placed infusion lines in children may occur for two reasons: 1) increased risk of catheter dislodgement (short, narrow-gauge infusion catheters placed in children with constantly moving extremities) and 2) difficulty of early detection of fluid extravasation (due to the thick subcutaneous skin layers surrounding infusion catheters).Figure 1: Necrosis after infiltration of hypertonic solution into a hand (A) and foot (B).The traditional approach for evaluation of intravenous lines prior to use (especially lines started by others prior to arrival in the operating theater) is to check the site for redness, tenderness, etc., check connections, and observe the line for blood return when opened to air below the level of the heart. Blood return is good evidence that the tip of the intravenous line is truly within the lumen of the vein. If no blood return is observed, a syringe is used to irrigate the line with crystalloid. The line again is opened to air and observed for blood return. Failing this, an evaluation of the ease of syringe crystalloid infusion is made. In the past, we have occasionally been misled by an intravenous line that irrigates well and drips well, but ultimately is proven not to be intravascular (especially common with lines located in the saphenous or antecubital areas). For the last 2-3 yr, we have employed an additional test to help confirm intravascular placement of the intravenous lines prior to use. The line is allowed to drip via gravity and the rate of flow observed. Then, a hand encircling the extremity (with tourniquet effect) is placed well above the tip of the intravenous catheter Figure 2. If this maneuver quickly stops or significantly slows the flow of intravenous fluid, this suggests proper intravascular placement of the line. If the test fails to alter significantly the rate of flow of the line, extravascular placement must be suspected. The test does not rule out the possibility that only the very tip is intravascular, and that subsequent movement of the extremity might dislodge the tip to an extravascular position. We presume that this test works by occluding venous return proximal to the intravenous catheter. As intravascular venous pressure approaches drip chamber pressure, flow slows and then stops. In the case of a catheter that seems to function (drips and irrigates well) but is extravascularly placed, a tourniquet effect proximal to the catheter will not have this effect.Figure 2: Use of manual pressure encircling extremity above the infusion catheter to check appropriate intravenous placement. Note that the encircling hand is placed well above the tip of the catheter to prevent misinterpretation because of direct manual occlusion of the catheter tip.While there is no absolute clinical test to rule out the possibility of extravasation of fluids intended for intravenous routes, this test provides another simple, rapid assessment of intravenous location prior to use. G. W. Stevenson, MD Bruce Bauer, MD Steven C. Hall, MD Departments of Pediatric Anesthesia and Plastic Surgery, Children's Memorial Hospital, Northwestern University Medical School, Chicago, IL 60614