Purpose of the Study Critical illness requiring life support affects over 150 000 people in Ontario every year. With aggressive support, the number of people who die from critical illness is decreasing. However, people who survive often have neurological problems. These neurological problems often include difficulties with memory, concentration, and attention. These problems are associated with poor quality of life among survivors of critical illness. The aim of this study is to identify the factors that contribute to these neurological deficits. Specifically, the investigators are testing whether changes in oxygen delivery to the brain during critical illness are related to both short- and long-term neurological complications.

Procedures involved in the Research When patients are diagnosed with a critical illness such as shock or respiratory failure, they are treated with intravenous fluids, medications to raise their blood pressure, and can be placed on a ventilator to assist with their breathing. They are observed in an intensive care unit (ICU). This research protocol does NOT interfere with the normal treatment of patients with critical illness. The procedure involved in this research protocol requires the placement of two stickers to either side of the patient's forehead, and information about oxygen delivery to the brain will be recorded. When the patient has recovered from the critical illness, they will be asked to perform several neurological tests. Some of these tests will be done with a pencil and paper, while others will use a robotic device to test arm movements, reaction time, and concentration.

Potential Harms, Risks or Discomforts:

This research study involves the placement of a sticker sensor to either side of the forehead. Rarely, patients may develop a rash to these electrodes. The investigators monitor patients very carefully for rashes, and if a rash is to occur, the sticker sensor will be removed. With regards to the neurological testing, rarely patients can have some mild muscle stiffness after moving their arms in the robot. The investigators do not expect any other further harms, risks, or discomforts.

A detailed protocol is currently under review for funding at Physician Services Incorporated, and can be included pending decision.

Inclusion Criteria:

• Critically ill patients defined as having either:

  1. Respiratory failure: Defined as invasive mechanical ventilation for a predicted duration of >24 hours, or:
  2. Shock: Defined as being on one of the following agents:

• norepinephrine (>5 mcg/min) IV

• epinephrine (at any dose)

• vasopressin (in combination with another pressor)

• milrinone (in combination with another pressor)

Exclusion Criteria:

• expected survival <24 hours
• history of cognitive dysfunction
• unable to participate in follow up testing

This study is recruiting critically ill patients admitted to the 33-bed medical/surgical intensive care unit at an academic medical centre.

We will publish our data in a peer reviewed scientific journal