This study is to determine whether accelerometry can be used to measure physical activity occurring during routine clinical care in a diverse population of patients with medical or surgical critical illness.

Patients that meet inclusion criteria will have a wristwatch size, lightweight ActiGraph GT3X+ placed at each of three body sites, the dominant-side wrist, right hip and dominant-side ankle to objectively measure physical activity. Patients will wear the ActiGraph devices during two 30-minute periods of direct observation. To compare activity counts measured by the ActiGraph devices with directly observed purposeful physical activity, we will record the time and type of physical activity performed by patients such as sitting at the edge of the bed, sitting in a bedside chair, transferring to a chair, standing and ambulating. The data acquired from this observational (AMERCIA) study will seek to establish the feasibility of using accelerometers to measure activity in a diverse population of patients with medical or surgical critical illness.

Inclusion Criteria:

Patients will be included if they are:

1. adult patients,
2. admitted to the medical or surgical ICU,
3. receiving or have received invasive or non-invasive mechanical ventilation for respiratory failure or vasopressors for shock (i.e., cardiogenic, hemorrhagic, septic or undifferentiated shock) within the last 48 hours, and
4. who are receiving routine physical and occupational therapy.

Exclusion Criteria:

Patients will be excluded if they meet any of the following criteria:

1. Those who have severe physical disability that prevented independent living prior to their illness,
2. Those unable to speak and communicate in English,
3. Expected death within 24 hours of enrollment or lack of commitment to aggressive treatment by the family or medical team (i.e., likely to withdraw life support measures within 24 hours of screening),
4. Inability to obtain informed consent from authorized surrogate;

A diverse population of adult patients with medical or surgical critical illness in the ICU.