Effect of Kinetic Therapy on Pulmonary Complications

Abstract & Commentary

Synopsis: Kinetic therapy decreased pneumonia and atelectasis but not length of stay in the ICU, length of stay in the hospital, or mortality.

Source: Ahrens T, et al. Am J Crit Care. 2004;13:376-383.

The primary objective of this study was to determine whether patients receiving mechanical ventilation who tolerate kinetic therapy have better pulmonary function than patients treated with standard turning. A secondary objective was to assess the cost-effectiveness of kinetic therapy. This was a prospective multicenter study including 234 medical, surgical, and trauma patients (137 control patients and 97 patients receiving kinetic therapy). There were an additional 21 patients assigned to receive kinetic therapy who were not included in the analysis because they did not tolerate the therapy.

Kinetic therapy significantly decreased the occurrence of ventilator-associated pneumonia (P = 0.002) and the development of lobar atelectasis (P = 0.02). The length of stay in the intensive care unit and in the hospital did not differ between the patients receiving kinetic therapy and control patients. Charges for intensive care were not significantly different between the groups. Mortality was the same in both groups. Ahrens and colleagues concluded that kinetic therapy helps prevent ventilator-associated pneumonia and lobar atelectasis in critically ill patients.

Comment by Dean R. Hess, PhD, RRT

Beds for kinetic therapy rotate in a turn of at least 40 degrees, whereas beds for continuous lateral rotation therapy rotate less than 40 degrees. The use of these beds has become popular in many intensive care units—attributable, in part, to the marketing efforts of their manufacturers. Due to the high costs associated with these beds, their use remains controversial. Studies to date have been single-center studies with small sample sizes and have failed to clearly make a case for or against the use of these beds. Therefore, I was initially excited to see this multi-centered, prospective, randomized, controlled trial of the effect of kinetic therapy on pulmonary complications.

However, there are several methodological issues that seriously limit the generalizability of the results published here:

1) Ahrens et al claim that this is a prospective randomized trial. However, close examination of the methods reveals that patients were assigned to the kinetic therapy group or the control group on an alternate month basis. This is not a randomized design and suffers the same risk of assignment bias as use of medical record number for group assignment.

2) It is unclear how valid was the detection of ventilator-associated pneumonia and lobar atelectasis. The assessors were not blinded to the therapy and their skills to identify ventilator-associated pneumonia and lobar atelectasis are not validated. A ventilator-associated pneumonia rate of 33% and a lobar pneumonia rate of 43% are reported for the control group—these are extraordinarily high, calling into question their validity!

3) Dropping 21% of the patients from analysis because they did not tolerate kinetic therapy is problematic. One in 5 patients did not tolerate the therapy! An appropriate analysis would be intention-to-treat rather than dropping these patients from the study. This analysis might have significantly biased the analysis.

4) The reporting of hospital charges is meaningless. It is well known that there is virtually no relationship between charges and costs.

Despite the limitations of this study, the results are similar to several meta-analyses that have been published on this use of kinetic therapy.1,2 That is, although the use of kinetic therapy may decrease the risk of ventilator-associated pneumonia and atelectasis, it does not affect other important outcomes such as mortality or hospital length of stay. Thus the cost-benefit of this therapy remains ambiguous. Some will argue that a decrease in the risk of ventilator-associated pneumonia is reason enough to use these beds. Others will demand additional patient-important outcomes such as mortality or cost of care.

An important question might be how kinetic therapy decreases the pneumonia rate without this translating into important outcomes like mortality? Perhaps the diagnosis of ventilator-associated pneumonia is over-reported. When the diagnosis is made on clinical criteria and the individuals making the diagnosis are not blinded to the study group, this is a strong possibility. Perhaps the antibiotic therapy chosen to treat the pneumonia is effective. Or, perhaps most likely, pneumonia is only one factor (and maybe a relatively minor factor) affecting patient outcome.

Unfortunately, the cost-effectiveness of these beds remains unknown even with the publication of this paper. What is debatable is whether a reduction in ventilator-associated pneumonia is sufficient evidence to support the use of these beds. This is likely to remain controversial until a properly designed study demonstrates an improvement in an important outcome like survival or the cost-effectiveness of the beds can be established using accepted methodology for such analysis.

References

1. Choi SC, Nelson LD. J Crit Care. 1992;7:57-62.

2. Marik PE, Fink MP. Crit Care Med. 2002;30: 2146-2148.

Dean R. Hess, PhD, RRT, Respiratory Care Massachusetts General Hospital Department of Anesthesiology Harvard Medical School, is Associate Editor for Critical Care Alert.