Rationale: Little is known about the safety of infusing vasopressors through a midline catheter. Objectives: To evaluate safety outcomes after vasopressor administration through a midline. Methods: We conducted a cohort study of adults admitted to 39 hospitals in Michigan (December 2017-March 2022) who received vasopressors while either a midline or peripherally inserted central catheter (PICC) was in place. Patients receiving vasopressors through a midline were compared with those receiving vasopressors through a PICC and, separately, to those with midlines in place but who received vasopressors through a different catheter. We used descriptive statistics to characterize and compare cohort characteristics. Multivariable mixed effects logistic regression models were fit to determine the association between vasopressor administration through a midline with outcomes, primarily catheter-related complications (bloodstream infection, superficial thrombophlebitis, exit site infection, or catheter occlusion). Results: Our cohort included 287 patients with midlines through which vasopressors were administered, 1,660 with PICCs through which vasopressors were administered, and 884 patients with midlines who received vasopressors through a separate catheter. Age (median [interquartile range]: 68.7 [58.6-75.7], 66.6 [57.1-75.0], and 67.6 [58.7-75.8] yr) and gender (percentage female: 50.5%, 47.3%, and 43.8%) were similar in all groups. The frequency of catheter-related complications was lower in patients with midlines used for vasopressors than PICCs used for vasopressors (5.2% vs. 13.4%; P < 0.001) but similar to midlines with vasopressor administration through a different device (5.2% vs. 6.3%; P = 0.49). After adjustment, administration of vasopressors through a midline was not associated with catheter-related complications compared with PICCs with vasopressors (adjusted odds ratios [aOR], 0.65 [95% confidence interval, 0.31-1.33]; P = 0.23) or midlines with vasopressors elsewhere (aOR, 0.85 [0.46-1.58]; P = 0.59). Midlines used for vasopressors were associated with greater risk of systemic thromboembolism (vs. PICCs with vasopressors: aOR, 2.69 [1.31-5.49]; P = 0.008; vs. midlines with vasopressors elsewhere: aOR, 2.42 [1.29-4.54]; P = 0.008) but not thromboses restricted to the ipsilateral upper extremity (vs. PICCs with vasopressors: aOR, 2.35 [0.83-6.63]; P = 0.10; model did not converge for vs. midlines with vasopressors elsewhere). Conclusions: We found no significant association of vasopressor administration through a midline with catheter-related complications. However, we identified increased odds of systemic (but not ipsilateral upper extremity) venous thromboembolism warranting further evaluation.
Keywords: catheter-related infections; central venous catheters; peripheral catheterization; vasoconstrictor agents; venous thromboembolism.