Learning curve of vessel cannulation in rats using cumulative sum analysis

Intravascular access routes are widely used for administering agents or taking blood samples in rodents. Vessel cannulation in rats is a technically challenging procedure with a risk for significant complications. The use of cumulative sum (CUSUM) analysis allows continuous monitoring of the performer's outcomes to evaluate the learning curve for a particular procedure. The aim of the present study was to assess a researcher's learning curve in the cannulation of the jugular and femoral vein in rats using CUSUM analysis.

A single researcher performed two hundred microsurgical operations between September 2012 and September 2013. The animals (male Wistar rats) were anesthetized with isoflurane whereas the right jugular vein and the left femoral vein were catheterized. Prospective data were collected and analyzed using CUSUM analysis. For the purposes of the study, the rat population was divided in four groups based on the order of studies; group 1 represents the first 50 animals cannulated, group 2 the next batch of 50 animals, and so forth.

The operating times required for cannulation of the jugular vein for groups 1, 2, 3, and 4 were 24.6 ± 4.8, 15.9 ± 2.5, 15.2 ± 3.2, and 15.7 ± 3.3 min, respectively. Group 1's operating time was significantly longer than all the other groups (P < 0.001 compared with all other groups). The operating times for groups 2, 3, and 4 did not differ significantly (P > 0.05). The cannulation of the femoral vein required a mean of 32 ± 5.3 min for group 1, 24.9 ± 5.7 min for group 2, 18.4 ± 4 min for group 3, and 17.2 ± 3.4 min for group 4. The operating time of group 1 was significantly longer when compared with all groups (P < 0.001 for all groups). Group 2 also had a longer operating time than groups 3 and 4 (P < 0.001 compared with both groups). Groups 3 and 4 did not show any statistical significant difference when their operating time was compared (P > 0.05). CUSUM analysis suggested that the number of cases required to achieve the required experience to most effectively cannulate the jugular and femoral vein is approximately 50 and 100 cases, respectively. The adverse effects of the procedure included two unexpected deaths, both of which occurred in group 1 (0.5% in total).

The authors' experience regarding the learning curve of the cannulation of the femoral and jugular vein in rats from 200 animals operated over a period of 1 y for the evaluation of the pharmacokinetic properties of drug candidates suggests significant experience is required to optimize the operating time required for the procedure.