Abstract

The adverse effects of prolonged immobility are due primarily to gravitational effects on blood flow and ventilation, impairment of the normal mucociliary escalator and possibly an increase in extravascular lung water. However, CLRT theoretically should reverse these abnormalities. The sequence of events that culminate in LRTI or pneumonia is unclear; however, low tidal volumes, increased extravascular lung water and the accumulation of bronchopulmonary secretions may lead to atelectasis, a well-known precursor of pneumonia. Three prospective, randomized studies evaluating patients with acute head trauma, orthopedic injuries requiring traction and blunt chest trauma all showed a decreased incidence of LRTI or pneumonia with CLRT compared with those treated in a conventional bed and turned every 2 h by the nursing staff. In general, the methodology was sound with early randomization, use of precise criteria to define LRTI and pneumonia and appropriate observation. The fourth study performed in a medical ICU with a heterogeneous group of patients did not show a difference in incidence of nosocomial pneumonia between treatment in CLRT and a conventional bed, but did show a decreased length of ICU stay for patients with pneumonia treated with CLRT. It appears that if CLRT is to be effective, it needs to be instituted early in the patient's illness. The length of time that CLRT should be utilized is unknown; however, intuitively, as long as the patient is at risk, the therapy should be continued. It is also unclear whether CLRT should be started at full rotation immediately or begun at lesser degrees of rotation and advanced serially over several hours. Another unknown is the minimum time that CLRT should be administered per day. In the studies discussed, most patients were rotated for 10 to 16 h/day. The minimum degree of rotation necessary for an effect is also unknown; in the studies cited, rotations from 40 degrees to 62 degrees in each direction were used. Based on the current data, the early use of CLRT in comatose or otherwise immobile patients decreases the incidence of LRTI including pneumonia over the first 7 to 14 days of ICU care. The prevention of pneumonia and more rapid transfer from the ICU should offset the additional expense of a specialized bed. The data suggest that a multicenter study with accrual of a large number of patients to evaluate this form of therapy in a prospective, randomized study is necessary. If the hypothesis that CLRT decreases the incidence of nosocomial pneumonia in the ICU is proven, the impact on critical care in the 90s would be substantial.