UPDATE R
SET IsOrphaned = 1, DebugTimestampUtc = GETUTCDATE()
FROM
    RequestTable AS R
    LEFT JOIN sys.sysprocesses AS P ON
        P.spid = R.SPID
WHERE P.spid IS NULL

INSERT INTO RequestTable(SPID, CreateTimestampUtc, ...)
SELECT @@SPID, GETUTCDATE(), ...
WAITFOR DELAY '00:00:30.000'