A simple technique to assess postoperative epidural functionality

To describe an alternative method of measuring the Epidural Waveform Analysis (EWA), a technique through which anesthesiologists can confirm the position of a needle and/or catheter tip in the epidural space. EWA consists of epidural catheter transduction with a pressure system typically used for invasive arterial blood pressure monitoring which generates a characteristic oscillatory waveform (provided the catheter tip is within the epidural space) in synchrony with the pulsatile epidural circulation. The technique requires a double-male connector, a 3-way stopcock and an arterial pressure extension tubing along with the patient's existing arterial line setup while ensuring a meticulously sterile technique to mitigate the risks of neuraxial infection. The technique described herein has been successfully and routinely applied within our institution to measure EWA with the advantage of being potentially less wasteful. EWA allows anesthesiologists to confirm the correct position of an epidural needle/catheter. We describe a method of successfully measuring EWA while reducing wastefulness.