This study is designed to assess the feasibility of identifying and administering individualized blood pressure targets early critical illness. Recent literature suggests that individualized targets adapted to cerebral perfusion and autoregulation capacity may improve patient outcomes. In this study, cerebral autoregulation capacity is assessed by simultaneous trending of near-infared spectroscopy and arterial blood pressure for 24 hours, within patients' first 2 days in the ICU. The investigators will assess the feasibility of identifying patients' personal targets, then treating patients according to their personal targets for 48 hours. Clinical outcomes explored will include delirium.

Inclusion Criteria:

1. Admitted to a critical care unit requiring one or more of the following:

   1. Respiratory failure requiring invasive mechanical ventilation with an expected duration >24 hours or
   2. Shock of any etiology. Shock is defined by the need for one of the following vasopressors/inotropes: i. Dopamine ≥7.5 mcg/kg/min, ii. Dobutamine ≥5 mcg/kg/min, iii. Norepinephrine ≥5 mcg/min, iv. Phenylephrine ≥75 mcg/min, v. Epinephrine at any dose, vi. Milrinone at any dose (if used in conjunction with another agent), vii. Vasopressin ≥0.03 u/min (if used in conjunction with another agent)

2. Presence of an arterial line

Exclusion Criteria:

1. Admission to the ICU > 24 hours
2. Life expectancy <24 hours
3. Primary central nervous system admitting diagnosis (e.g. traumatic brain injury, stroke, subarachnoid haemorrhage, cardiac arrest).
4. Pregnancy
5. Any reason that the subject may not be able to participate in the follow up assessments (i.e. limb amputation, paresis, neuromuscular disorders)

We are open to sharing individual participant data that underlie the results reported in this article after deidentification (text, tables, figures, appendices). Data sharing would be available to interested researchers for IPD meta-analysis or other research aims for which IPD is necessary. Proposals should be directed to study contact Dr. Gordon Boyd at Gordon.Boyd@kingstonhsc.ca. To gain access, data requestors will need to sign a data access agreement.

Beginning 3 months and ending 5 years following article publication

Researchers who provide a methodologically sound proposal and received ethics approval for their proposal