Patient enrollment to low to support an analysis

This is a 10-week pilot study for a randomized non-blinded controlled clinical trial to assess whether use of the Rifton Gait Trainer will improve the incidence of mobilization of critically ill ventilator dependent patients in the intensive care units (ICUs) and improve important patient outcomes. The pilot study is designed to assess the feasibility and logistics of doing a study of this nature in the ICU; it will also provide the means to obtain estimates of outcome effect sizes, number of repeated measures, time between repeated measures, and intra-subject and intra-unit correlations, to be used for sample size calculations.

Background Critical care costs an estimated 90 billion dollars per year in the United States, comprising approximately 1% of the gross national product.1 Though this expenditure is enormous, together with advances in critical care medicine and mechanical ventilation technology, it has produced a priceless trend in decreasing intensive care unit (ICU) mortality.1 Of all ICU admissions, about 40% require mechanical ventilation, often with accompanying necessary periods of sedation and inactivity.1 Although more patients are surviving their ICU stay, it is becoming apparent that our current ICU culture of heavy sedation and inactivity is taking its toll on the complete recovery of the critically ill patient. 1,2 Several studies have shown significant disability one year after discharge, as well as major declines in functional status and health-related quality of life; half of ICU patients were unable to return to work due to persistent fatigue, weakness, and poor functional status. 4 The primary contributor was muscle wasting and weakness,5 due to the prolonged immobilization brought about by illness, lengthy bed rest, deep sedation, and the use of paralytic agents.6 It is estimated that just a single day of inactivity causes muscle strength to decrease by 1-1.5%.7 Although 94% of survivors with critical illness myoneuropathy can demonstrate meaningful clinical recovery of muscle strength 9 months out from their hospital stay, there are still some patients whose weakness may persist, resulting in severe and prolonged functional deficits.14,18 To combat the deleterious effects of inactivity and improve complete recovery, some hospitals have instituted programs under the rubric early mobility, wherein sedation is reduced and patients are engaged in progressive levels of activity as soon as physically possible. Early mobilization starts with passive range of motion exercises, then progresses to active range of motion, sitting, standing, and, finally, walking. Early mobility in the ICU has been proposed as a crucial instrument in muscle preservation and protection from neuropathy of critical illness, thereby decreasing long-term morbidity and physical debilitation.18

There is a growing body of evidence indicating that early mobilization of ventilated patients can have a significant positive impact on length of stay, muscle condition, and the patient's overall sense of well-being. The use of early mobility in patients with respiratory failure has been proven safe with the implementation of proper monitoring in a physiologically stable and awake patient.2 Hopkins et al. implemented an early activity program and demonstrated a decline in length of ICU stay of 3 days.1 Morris et al. implemented a similar early mobilization program that showed a statistically significant decrease in the length of stay in the ICU (6.9 vs. 5.5 days, P=0.025) as well as in the hospital (14.5 vs. 11.2 days, P=0.006); in addition there was a notable trend towards decreased inpatient cost per patient ($44,302 vs. $41,142, P=0.262).19 Schweikert et al. were able to demonstrate that patients who had undergone early mobilization had a greater rate of return to independent functional status at hospital discharge (59% vs. 35%, P=0.02).20 These studies have demonstrated the ability to increase mobilization, improve physical function, and decrease ICU resource utilization within a relatively short period of time with an appropriate change in routine clinical practice.12

Unfortunately, there exist significant barriers to the implementation of an early mobility program. The most significant and pervasive of these barriers is cultural-the perception that the critically ill patient cannot tolerate physical activity. This barrier, however, is rapidly dissolving with the mounting evidence noted above. The demonstrated benefits of early mobility have prompted increasing numbers of institutions to develop their own early mobility protocols and attempt their implementation. Once the cultural barriers are overcome, however, additional barriers appear. Thus, implementation has been slow and spotty. In a multisite study, only 27% of patients with acute lung injury received any form of physical therapy in the ICU, with treatments occurring only 6% of those days.22 These barriers involved: 1) providing safety guarantees, 2) accommodating staffing models, and 3) finding the right hardware. With regard to safety guarantees, there exist legitimate fears regarding possible harm to the patient in the process of mobilization, either secondary to patient falls, or unintentional removal of lines, feeding or drainage tubes, or endotracheal tubes. Safe mechanical support is needed for the patient, to the point of full body-weight support. The staffing model is also critical: the mobilization of one ventilated patient requires, in addition to a physical therapist, at least three staff members to move medical equipment while the patient walks.11, 21 Although on a given day, within a 20-bed ICU, only two patients might qualify for assisted walking, and would require only four 15-minute periods from a 5-member mobility team per day, the logistics of assembling that team from the ICU staff are often prohibitive. Finally with regard to finding appropriate hardware, the management and transport of medical equipment alongside the walking patient is not easily addressed with rolling poles and carts. The current standard of care for walking a mechanically ventilated patient consists of a wheeled walker held onto by the patient, the patient supported with a gait belt held from behind by a physical therapist, and 4-5 staff persons in attendance to guide the patient, roll the equipment, and be ready to "pick up" should the patient fall.

As an alternative to the front-wheeled walker, the Rifton Gait Trainer has been introduced into clinical practice. This device provides greater inherent safety features via a pelvic harness that keeps the patient from falling, even if their legs should give out while walking. In addition, there is a chest piece to keep patients from tipping forward or backward, and there are higher handholds to help patients mobilize more easily. The Rifton Gait Trainer addresses two of the three above listed barriers by providing more inherent safety features through better hardware, and it may also help decrease the number of staff required to mobilize patients.

Purpose The following sections describe a 10-week pilot study for a randomized non-blinded controlled clinical trial to assess whether use of the Rifton Gait Trainer will improve the incidence of mobilization of critically ill ventilator dependent patients in the intensive care units (ICUs) and improve important patient outcomes. The pilot study is designed to assess the feasibility and logistics of doing a study of this nature in the ICU; it will also provide the means to obtain estimates of outcome effect sizes, number of repeated measures, time between repeated measures, and intra-subject and intra-unit correlations, to be used for sample size calculations for a multi-center study.

Subjects Approximately forty subjects will be randomized to use either the RGT or the FWW, with enrollment spanning a period of approximately 10 weeks. Patients will be deemed eligible to ambulate based on their daily mobility score, as calculated according to the Early Mobility Protocol. Mobility scores are first determined based on level of consciousness. The unconscious patient has the lowest mobility level, Level 1. Patients who are conscious but have a low RASS score (-2) are considered a Level 2. Conscious patients are considered to be Level 3 or 4. Level 4 patients are those patients who have proven that they can master all the activities outlined for Level 3 mobility; that is, they can dangle at the bedside and stand and pivot to a chair. Level 4 activities are separated from Level 3 activities only by the ability to walk in the hallway.

Informed consent will occur prior to randomization. Randomization will occur when patients have been on the ventilator > 2 days and have mobility scores eligible for walking. Randomization will be assigned on a 1:1 ratio to either the RGT or FWW. Patients will be randomized using a web-based system called CREDIT.

Data Analysis A future study will be considered feasible if we are able to enroll 60% of eligible patients, have records for 90% of eligible ambulation days, and at least 85% of required data fields are completed as designed. Analysis will be based on intention-to-treat; that is, regardless of which walker is actually used, the patient will be analyzed in the group to which he or she was randomized.

The primary outcome measure, how many times the patient is mobilized each day, will be compared between devices using a hierarchical generalized linear model with number of times the patient is mobilized each day as the dependent variable, device, unit and day and an interaction of device with day as the independent variables, and subject as the random effect in the model. Most likely, ordinal regression will be used with 0, 1, 2 or more times as the definition of outcome. If there are too few occurrences of 2 or more, we will convert to a logistic model. If one device is better than the other, we would expect the odds of being mobilized at a higher level with RGT is significantly different from the odds of being mobilized with FWW. We will also test for the interaction of device with time.

Sources

Inclusion Criteria:

• >18 years of age
• On the ventilator for > 48 hours
• Mobility score > 3

Exclusion Criteria:

• > 220 lbs
• Limb amputees
• Prisoners
• Pregnant women

The study was never completed due to feasibility issues.

Not applicable; study was never started