Intraoperative hypotension predicts organ injury, including acute kidney injury, although the route from low perfusion to injury is complex and unclear. An article and editorial in this issue discuss a particular mean arterial pressure (55 mmHg) which, on average, seems to impart risk, and why an absolute definition of hypotension is elusive.

  • Brady and Hogue: Intraoperative Hypotension and Patient Outcome: Does “One Size Fit All?” p. 495

  • Walsh et al.: Relationship between Intraoperative Mean Arterial Pressure and Clinical Outcomes after Noncardiac Surgery: Toward an Empirical Definition of Hypotension, p. 507