instruction: during the current hospital visit, what was the average bicarbonate value for patient 4401?
response: SELECT AVG(labevents.valuenum) FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 4401 AND admissions.dischtime IS NULL) AND labevents.itemid IN (SELECT d_labitems.itemid FROM d_labitems WHERE d_labitems.label = 'bicarbonate')