It is unclear if blood pressure targets for patients with shock should be adjusted to pre-morbid levels. We aimed to investigate mean deficit between the achieved mean perfusion pressure (MPP) in vasopressor-treated patients and their estimated basal (resting) MPP, and assess whether MPP deficit has any association with subsequent acute kidney injury (AKI). Materials and Methods: Fifty-one consecutive, non-trauma patients, aged =. 40 years, with =. 2 organ dysfunction and requiring vasopressor =. 4 hours were observed at an academic intensive care unit. Mean MPP deficit [= (basal MPP - achieved MPP)/basal MPP] and time spent with >. 20 MPP deficit were assessed during initial 72 vasopressor hours (T0-T72) for each patient. Results: Achieved MPP was unrelated to basal MPP (P = .99). Mean MPP deficit was 18 (95 CI 15-21). Patients spent 48 (95 CI 39-57) time with >. 20 MPP deficit. Despite similar risk scores at T0, subsequent AKI (=. 2 RIFLE class increase from T0) occurred more frequently in patients with higher (>. median) MPP deficit compared to patients with lower MPP deficit (56 vs 28 ; P = .045). Incidence of subsequent AKI was also higher among patients who spent greater time with >. 20 MPP deficit (P = .04). Conclusions: Achieved blood pressure during vasopressor therapy had no relationship to the pre-morbid basal level. This resulted in significant and varying degree of relative hypotension (MPP deficit), which could be a modifiable risk factor for AKI in patients with shock.