How to save file descriptor returned from gdbus call in bash?

Question

I'm trying to use

#!/bin/bash
sudo gdbus call -y -d org.freedesktop.login1 \
                   -o /org/freedesktop/login1 \
                   -m org.freedesktop.login1.Manager.Inhibit \
                   sleep me because block
sleep 10

to acquire an inhibitor lock in a bash script. The introspection for this method looks like this:

Inhibit(in  s what,
        in  s who,
        in  s why,
        in  s mode,
        out h pipe_fd);

After my call to gdbus is done, no inhibitor lock is shown as acquired when listing with systemd-inhibit --list. I assume this is because the lock is acquired and then immediately released when exiting from gdbus.

How can I duplicate the returned file descriptor, pipe_fd, from the method call so it doesn't release the lock immediately after exiting from the call?