Category: Professional Posters
Purpose: When administering IVIG, the rate of infusion must be slowly titrated up to the maximum rate due to the risk of infusion-related adverse events increasing with a faster infusion rate. Thus, it is important to start the patient on the correct initial rate of infusion using the appropriate weight. The purpose of this medication use evaluation was to determine if nurses at Michigan Medicine were using the correct weight (ideal, actual, or adjusted) for calculating initial IVIG infusion rates for patients in the outpatient setting, according to hospital guidelines, and if incorrect initial rates were associated with infusion-related adverse events.
Methods: A retrospective analysis was done for a dataset that included all adult outpatient encounters from 09/04/2018 to 10/11/2018 at the Taubman Infusion Center where Gamunex-C or Gammagard (both IVIG) was administered. All included encounters received an initial infusion rate of 0.5 mL/kg/hr. Encounters with initial infusion rates of 0.25 mL/kg/hr and deceased patients were excluded. Electronic medical records (MiChart) were used to collect the following data: indication, treatment date, first infusion (Yes/No), weight on treatment day, height, initial rate of IVIG, and infusion-related adverse events. From the initial rate of IVIG, the weight used by nurses in kilograms (WKG) was derived. From the height and weight on treatment day (actual body weight), the ideal and adjusted body weights were calculated. WKG was categorized as actual, ideal, or adjusted body weight. An additional category of “other” was added for WKGs that did not match with any of the three weight categories. Encounters were further excluded from analysis if WKG belonged in two or more weight categories. After the matching process, it was determined whether the nurses were using the “correct” or “incorrect” weight based on the current IVIG guidelines at Michigan Medicine. Frequency of infusion-related adverse events were then compared between patients receiving “correct” and “incorrect” initial IVIG infusion rate.
Results: 52 out of the 62 encounters were analyzed. We excluded ten encounters in total: four encounters for using 0.25 ml/kg/hr as the starting infusion rate, one patient encounter with a deceased patient, and five encounters with WKG that belonged in two or more weight categories. Eight of the encounters were categorized as “other,” two of which used double the actual weight and resulted in adverse events. Seven encounters were a first-time IVIG infusion, all seven of which used the wrong weight to calculate the initial infusion rate. One of these seven encounters experienced an adverse event. 90.4% (n=47) of the encounters used the incorrect weight for calculating initial infusion rate. The most common error in 63.8% (n=30) of the encounters was using the actual weight when ideal or adjusted should have been used. There were 36.2% (n=17) adverse events among the 57 encounters. Four of these were from the five encounters that used the correct weight and 13 from encounters that used the wrong weight. The most common adverse event was increased blood pressure. Some other adverse events were increased respiration, increased pulse, and headache.
Conclusion: The evaluation found that nurses used the wrong weight to calculate the initial infusion IVIG rate and many patients received faster infusions than indicated by the “Guidelines for IVIG Dosing and Administration” from Michigan Medicine. Necessary steps should be taken to properly train nurses and improve the EMR to provide the “correct” weight before initiating infusions. This evaluation did not show an association between using the wrong weight and the frequency of infusion-related adverse events. Future studies that analyze more encounters over a longer time period are needed.