This study will examine the effects of once and twice daily activity performed with patients who are breathing with the aid of a machine in an intensive care unit. Activity can occur in bed. Activity can include transfer to a chair and even walking once the patient's condition allows safe, out-of-bed activity. The investigators hypothesize that early, progressive activity will reduce inflammatory molecules in the blood, promote muscle and physical health and help patients to recover more quickly from critical illness.

Early therapeutic mobility (ETM) activity has been recommended to facilitate recovery and improve outcomes for the survivors of critical illness who experience prolonged mechanical ventilation. The effective dose (i.e., type, frequency and duration) of ETM activity is not known and there are limited reports about the application and effects of ETM in mechanically ventilated intensive care unit (ICU) patients. Three inflammatory biomarkers, interleukin (IL)-6, IL-10 and C-reactive protein, are potentially altered by a single episode of ETM activity. Systemic markers of physical health (i.e., vital signs, delirium, muscle strength, ventilator associated pneumonia, and duration of mechanical ventilation) may also be positively influenced by ETM. The primary aim of this interdisciplinary study is to compare the immediate effects of frequency--single and twice daily episodes--of ETM activity and the effects of type--low and moderate intensity--of ETM activity on molecular biomarkers of inflammation and systemic markers of physical health in mechanically ventilated adults. This is an experimental design, using repeated measures; subjects will be randomized to receive either one or two episodes of ETM activity daily during week days while in the ICU. Type of activity will be determined by patient condition. The research questions are:

1. a. What are the differences between the frequency (once versus twice daily) of ETM activities on inflammatory biomarkers: interleukin (IL)-6, IL-10 and C-reactive protein (CRP)? 1.b. What are the differences between the type (low or moderate) of ETM activities on inflammatory biomarkers: IL-6, IL-10 and CRP?
2. a. What are the differences between frequency of ETM activities on systemic markers of physical health: vital signs, delirium, muscle strength, ventilator-associated pneumonia and duration of mechanical ventilation? 2.b. What are the differences between type of ETM activities on systemic markers of physical health: vital signs, delirium, muscle strength, ventilator-associated pneumonia and duration of mechanical ventilation?

Data will be collected for a maximum of 3 contiguous days in ICU patients who are mechanically ventilated for >48 hours, then weekly to examine short-term patient responses to ETM activities in this preliminary study. Daily episodes of activity will be provided by a study interventionist. Repeated measures MANCOVA and ANCOVA will be used to answer the research questions. This collaborative study evaluates a biobehavioral methodology within an interdisciplinary team consistent with the biobehavioral methods to improve outcome research (PA-07-008) and the mission of the National Institute of Nursing Research to improve treatments and health based on evidence.

Inclusion Criteria:

• Adult patients who require invasive mechanical ventilation for more than 24 continuous hours in the surgical (SICU) or medical ICU (MICU)
• a P:F ratio > 100
• FiO2 < 60% and PEEP less than 10 cmH20 at baseline
• resting vital signs of HR 50-110, mean arterial pressure (MAP) 60-110 mmHg, peripheral oxygenation saturation (SpO2) greater than 88%. Exclusion Criteria:
• There are no exclusions based on gender or minority status.
• Patients will be excluded if they have pre-existing or current neurological, muscular or orthopedic disorders that require inactivity or immobilization during acute care or experience paresis/paralysis that will not improve. Examples of exclusionary conditions include end-stage muscular dystrophy, myasthenia gravis, new quadriplegia, coma, increased intracranial pressure, unrepaired hip fracture and multiple lower extremity fractures.
• Patients for high risk of death will also be excluded, using criteria established by Norton et al.: ICU admission following a hospital stay of >9 days in the past 12 months; age >80 in the presence of 2 or more life-threatening illnesses (e.g., end-stage renal disease, severe heart failure (HF); diagnosis of an active stage IV malignancy; status post cardiac arrest; and diagnosis of intracerebral hemorrhage requiring mechanical ventilation.[99].
• Subjects over 400 pounds can be excluded from mobilization based on the judgment of the bedside nurse or project manager; if the risk for staff or patient harm from moving a patient with excessive weight is considered likely, mobilization will not occur.
• Criteria for exclusion include inability to stand or walk for at least 10 minutes prior to admission; inability to shift weight in bed or assist with turning, inability of staff to access bariatric equipment such as an overhead trapeze, chair, or walker.