Carter was on the day shift and Pratt was on the night shift. they were running parallel stories of the two shifts. many of the patients Carter treated during the day wound up with Pratt that night -- example, Heather, the drowning victim. Carter told her dad she might not make it, but Pratt was able to tell the dad she'd recover.
the gang member was treated by Carter and left the ER after attacking a member of a rival gang, and returned to the ER when Pratt was there, and died.
when Pratt was treating the firefighter, you saw the woman wand two kids whose husband had died earlier. later you saw Carter treating her husband.
and so on.