A prospective multi-centre international observational study of postoperative vasopressor use, designed to answer the question: 'What is the proportion of patients that receive vasopressor infusions? In the management of these patients;

• Are there variations in the practice between clinicians, hospitals or countries? If yes, are they associated with clinical outcome?
• What are the health economic impacts associated with receiving vasopressors?

Postoperative hypotension is a common occurrence following major non-cardiac surgery and the use of vasopressors in the postoperative period to support blood pressure following optimisation of fluid status is commonplace. Receipt of infused vasopressors postoperatively is considered as a surrogate indicator of significant vasodilation. However, the incidence of postoperative vasopressor therapy has never been described.

By contrast to septic shock, there is no uniform definition of postoperative vasoplegia. Receipt of any amount of vasopressor would provide an objective dichotomous definition but a limitation would be the inability to differentiate degrees of vasodilation. Use of a threshold dose of infused vasopressor to determine a definition is uncomfortably arbitrary. There have been trials of different vasopressors to treat postoperative vasoplegia in cardiac surgical patients and we intend to gather data to inform future design in noncardiac surgery.

In addition, there is evidence of substantial variation in the management of postoperative hypotension between centres, countries and continents. The variation is in assessment (cardiac output and invasive monitoring) and environment (post-operative care units, high-dependency units, ICUs) and management (use and choice of fluids and vasopressors/inotropes). We hypothesise that there is also variation in the incidence of organ dysfunction and the use of organ support, and in clinical outcomes including duration of stay and mortality.

Inclusion Criteria:

• Undergoing surgery (may be planned or unplanned)
• No plans for return home on the day of surgery, for medical reasons
• Age ≥ 18 on day of surgery

Exclusion Criteria:

• Cardiac surgery
• Obstetric surgery
• Transplant surgery
• Receiving long-term infusions of vasoactive drugs, such as epoprostenol
• Mechanical circulatory support: ventricular assist device, intra-aortic balloon pump, artificial heart or similar
• Already been enrolled in Squeeze

For Cohort B - One additional inclusion criterion:

• Receiving infusion of vasopressors that continues after the patient has left the operating room.

Adult Patients undergoing any non-cardiac surgical procedure.