Insulin Administration Safety Profile During Military En Route Critical Care Transports

The aeromedical evacuation environment introduces unique logistical and physiological stressors for both patients and medical staff. Treating critically ill patients in confined spaces, under low-light conditions, amid aircraft noise, and with limited resources increases the risk of adverse drug events (ADEs). However, the true frequency and impact of medication errors in the en route care (ERC) setting remain poorly documented in both civilian and military sectors. In-flight, Critical Care Air Transport (CCAT) teams administer multiple high-risk medications, including paralytics, analgesics, cardiac drugs, anticoagulants, and insulin. The current CCAT model for medication safety relies largely on healthcare personnel performing high-risk procedures without error. Yet, significant gaps remain in understanding the frequency, nature, and consequences of medication errors in the en route critical care (ERCC) military environment. The purpose of this study was to describe CCAT in-flight insulin administration, glucose monitoring, and related interventions. The findings will inform CCAT pre-deployment readiness training and guide future CCAT clinical care practice guidelines.

We conducted a retrospective review of CCAT mission records for patients who received insulin during transport by USAF CCAT between 2012 and 2022. Research nurses trained at the En Route Care Research Center (ECRC) in San Antonio reviewed and abstracted data from Form 3899L into an Excel database. Descriptive statistics and univariate analyses were conducted for patient demographics and key measurements using SAS (version 9.4, SAS Institute, Inc., Cary, NC). Subgroup analyses stratified by insulin administration route were performed. Differences in hypoglycemia rates between administration routes were compared using the Fisher exact test.

The records of 3,320 patients evacuated by CCAT between 2012 and 2022 were screened. After exclusion criteria were applied, 2,998 records were screened for insulin administration, among which 2% (59/2,998) documented at least one instance of insulin administration. Routes of insulin administration included 51 subcutaneous (SQ) injections, 15 intravenous pushes (IVPs), 13 continuous insulin infusions, and 3 unspecified. Four patients (6.8%) experienced at least one hypoglycemic event (blood glucose concentration [BG] <70 mg/dL). Of these, three patients (75%) were receiving insulin infusions for hyperglycemia. For the 13 patients on insulin infusions, the median infusion rate was 4.0 U/hour (IQR [2.75-8.25]), and six patients (46%) had at least one 2-hour interval without a documented BG check. Most (60%) episodes of IVP insulin administration lacked a glucose check within 1 hour.

Insulin infusions managed by CCAT teams were rarely administered but were associated with a relatively high hypoglycemia rate of 23%. Documented BG measures during intravenous insulin administration were inadequate. Unless a CCAT team can ensure reliable and undistracted glucose monitoring, SQ insulin should be considered the first-line treatment for hyperglycemia in the ERCC setting.