What are the reasons for doing a manual bolus?
I know one reason for doing a manual bolus is to observe the blood circuit for clotting. At what point of the tx should this be done?
Usually a bolus refers to an amount of fluid - e.g. heparin - given at the start of treatment or to a bolus of saline during treatment which could be because of cramping or other symptoms of too much fluid being drawn off. A saline bolus on the System One is also used as part of the filter flush process. The filter flush process is used on the System One to visually determine the health of the artificial kidney - check for the amount of streaking.
I give a bolus of heparin in the lines if I take dad off the machine, so he can go to the bathroom or something. This helps prevent the recirculating blood in the lines from clotting. The time allowed to be off the machine without reconnecting is 15 minutes.
For us Oz nocturnal HHDers on Fresenius, a manual initial bolus of heparin (6.0 in my case) is given to flood the circuit up front, I guess, to ensure no clotting. It then goes auto ( @ 1.1p.h in my case) for the rest of the treatment (minus an hour).