IV Assessment with a Geiger Counter to Prevent Infiltrations

Introduction: When injecting a patient intravenously, there is always a concern of infiltration. Sometimes an infiltration is noticeable, causing the patient pain or a visible knot above the injection site. However, some infiltrations take place without the technologist recognizing it has occurred. A compromised injection from a PET-CT injection can potentially impact results. In previous work, we used an external monitoring device to assess IV patency by injecting a partial PET-CT dose, before administering the entire dose, to prevent infiltration. Even though this technique was successful, external monitoring devices are not readily available in most departments. In the present work, we developed a new partial injection technique to assess IV patency with a piece of equipment that is commonly available, a Geiger Counter.

Methods: Three patients in the PET-CT department were injected with a partial injection technique and monitored with a Ludlum Model 3 Geiger Counter utilizing an attached pancake probe. For the first patient, an external monitoring device was used simultaneously with the Geiger Counter to assess validity of the Geiger Counter in response to dose assessment. The pancake probe was taped side up to the injection chair arm rest, underneath the patient's arm, proximal to the injection site. The Geiger Counter was set to a rate of 100x so that movement of the needle would be noticeable to the technologist. Instead of giving the full dose as a bolus injection, two injections were given. The first injection included a partial dose, and the second injection included the remaining dose. The partial dose injection was created by adding a couple drops of F-18 from the original dose syringe to a 10 mL saline syringe. The partial dose was injected into the patient’s IV, and the technologist observed the needle of the Geiger counter to ensure there was a noticeable rise during injection and fall after completing the injection. Upon completion of the partial injection, if there was a noticeable rise and fall of the needle, the second injection with the remaining dose of F-18 was then given to the patient. If the needle did not fall after the end of the partial injection, this could indicate an infiltration. If an infiltration was indicated, the technologist would remove this IV and start a new one without significant loss of the dose.

Results: All three patients injected with the partial injection technique demonstrated IV patency and no infiltration was indicated. The measurements demonstrated by the Geiger Counter varied with each patient. With one patient’s assessment, the Geiger Counter read 100 mR/hr while injecting the partial dose. After completing the saline flush, the reading dropped to 50 mR/hr, which ensured IV patency. The remaining dose was injected and during the injection the Geiger Counter read 150 mR/hr. After flushing with saline, the reading dropped back down to 50 mR/hr.

Conclusions: Our facility determined that IV patency can be assessed by using a partial injection technique and a Geiger Counter. Since compromised injections can potentially impact the diagnostic and quantitative results of a scan, every effort should be taken to ensure a quality injection. This injection technique could be beneficial to any PET-CT or Nuclear Medicine department to reduce infiltrations.

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