title: Mean perfusion pressure deficit during the initial management of shock--an observational cohort study.
abstract: OBJECTIVE
  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).
  
  
  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.
authors.affiliation: Department of Anaesthesia, Intensive Care and Pain Medicine, John Hunter Hospital, Newcastle 2305, Australia. Electronic address: rakshitpanwar@hotmail.com.
authors.forename: Rakshit
authors.initials: R
authors.lastname: Panwar
authors.forename: Nicholas
authors.initials: N
authors.lastname: Lanyon
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Davies
authors.forename: Michael
authors.initials: M
authors.lastname: Bailey
authors.forename: David
authors.initials: D
authors.lastname: Pilcher
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D009102:Multiple Organ Failure / Q000097:blood / Q000503:physiopathology; D011446:Prospective Studies; D012151:Resuscitation / Q000379:methods*; D012769:Shock / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*
chemical_list: D014662:Vasoconstrictor Agents
keywords: Blood Pressure; Intensive Care; Perfusion; Relative hypotension; Targets