During all the observations of Elly Koss, what was the highest Systolic Blood Pressure observed?
the highest Systolic Blood Pressure refers to MAX(DESCRIPTION = 'Systolic Blood Pressure') from observations;
SELECT T2.value, T2.units FROM patients AS T1 INNER JOIN observations AS T2 ON T1.patient = T2.PATIENT WHERE T1.first = 'Elly' AND T1.last = 'Koss' AND T2.description = 'Systolic Blood Pressure' ORDER BY T2.VALUE DESC LIMIT 1