Hello! I think the issue with the IV catheter insertion in 4:09 was not a valve. I think this was a rolling vein, which rolled away from the operator (you can see it happening in 4:39, where the vein has been pushed to the side of the catheter). This is also strongly suggested by the fact there was no adequate flush back of blood in the chamber (just a tiny drop, suggesting the operator may have just nicked the vessel). The catheter was never inside the vein, therefore the procedure failed. Ways to fix this would be to try and pin the vein down as you explain in the later clip, as well as go for a more abrupt sting during insertion (you can see the slow moving needle "tent" the skin for a second before it manages to get through, during which time the pressure from above allowed the vein to roll to the side).
Hello! I think the issue with the IV catheter insertion in 4:09 was not a valve. I think this was a rolling vein, which rolled away from the operator (you can see it happening in 4:39, where the vein has been pushed to the side of the catheter). This is also strongly suggested by the fact there was no adequate flush back of blood in the chamber (just a tiny drop, suggesting the operator may have just nicked the vessel). The catheter was never inside the vein, therefore the procedure failed. Ways to fix this would be to try and pin the vein down as you explain in the later clip, as well as go for a more abrupt sting during insertion (you can see the slow moving needle "tent" the skin for a second before it manages to get through, during which time the pressure from above allowed the vein to roll to the side).