Page 259 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 24: Physical Therapy 163

contraction was reduced by approximately 15% after 14 days of bed pressure. The significance of these findings to critically ill patients is
rest. Another measure, knee extensor strength, was reduced by 22% unclear; however, critically ill patients frequently experience complica-
23
after 14 days and by 53% after 28 days of limb immobilization. 24,25 Limb tions that may result from such vascular dysfunction.
casting models of immobilization suggest that the decline may be more
significant, reaching as high as 5% to 6% per day. 28,29 For the recumbent MOBILIZATION OF THE CRITICALLY ILL PATIENT
critically ill patient, the antigravity muscle groups—located in the legs,
trunk, and neck which function primarily to support the body—are Mobility has been recognized as a component of primary, secondary,
particularly “rested.” Accordingly, muscle atrophy with protracted rest is and tertiary prevention of overall disease morbidity and mortality.
more consistent and probably greatest in these muscles. Early ambulation was first introduced for inpatients during World
War II in an effort to expedite the recovery of soldiers for return to the
battlefield. Since then, early mobilization has yielded improved out-
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INACTIVITY AND OTHER ORGAN SYSTEM INJURY comes in such varied conditions as community acquired pneumonia to
orthopedic surgery. Given the known morbidity of ICU survivorship,
Loss of joint range of motion (ROM) occurs when the joints are not clinical researchers have targeted the avoidance of bed rest as a potential
subjected to normal mobility and stress. Immobility leads to synovial opportunity to affect the quality of life for survivors. These trials high-
fluid stasis and resultant increased intra-articular fluid volume and light that early exercise and mobilization is possible to conduct despite
pressure. Heightened tension, pain, and decreased ROM ensue. Most ongoing critical illness. Although most investigations have focused
ICUs are vigilant for this complication, and various measures to prevent selectively on patients undergoing MV, the results are likely generaliz-
contractures—such as ROM exercises and splinting—can prevent or able to broader populations of critically ill patients.
reduce contractures. However, one study of survivors of a 2-week
or longer critical illness found that joint contractures were identified in
61 of 155 patients. At the time of discharge from intensive care, 34% of PASSIVE RANGE OF MOTION
30
patients had at least one functionally significant contracture, and 23% The proposed goal of passive ROM exercise is to preserve of the range
of patients had functionally significant contractures persisting at the of the joint. Motion studies of the knee using radiolabeled tracers dem-
time of discharge home. The most commonly affected joints at the time onstrated that synovial fluid clearance rates can be increased under
of discharge home were the elbow (34%) and ankle (33%). conditions of passive motion. Simple joint motion creates fluctuations
39
Skin ulcers are a well-recognized phenomenon of bed immobiliza- in intra-articular pressure and avoids fluid stasis. In critical care prac-
tion and can serve as a portal of entry for bacteria. Breakdown occurs tice, periodic passive ROM exercises is an expectation of the bedside
at points of pressure between the skin and bed. Unrelieved pressure nurse, yet may be a necessary intervention by the physical therapist for
combines with impaired microcirculation, malnutrition, shear force, the patient unable to engage in activity.
and humidity to result in skin ulcers. Furthermore, elevation of the Technically, passive ROM differs from what is described as a pro-
head of the bed to reduce aspiration and ventilator-acquired pneumonia longed muscle stretch. A prolonged muscle stretch usually implies hold-
causes greater pressure at the skin-bed interface in the sacral region. 31,32 ing a muscle or group of muscles in a lengthened position for a period.
Frequent shifts of body position are preventive. The purpose of “splinting” a joint follows from this notion that passive
Lung compliance is reduced substantially during immobilization in muscle stretch leads to maintenance of both the joint and muscle’s base-
the supine position. The diaphragm shifts cephalad and combines with line range.
the dorsal shift of the heart from the force of gravity, results in partial or The evidence to support the use of passive movements as part of a
complete atelectasis of the left lower lobe within 48 hours of recumbency program of early mobilization is weak. The limited evidence suggests that
in critically ill patients. Additional atelectasis in other dependent lung passive movements may prevent protein degradation, maintain muscle
regions is frequently apparent on computed tomography. This atelectasis mass, and alter the inflammatory profile in humans. For example, in
may predispose to pneumonia, raise pulmonary vascular resistance, and 20 subjects with severe sepsis or septic shock randomized to 30 minutes
yield intrapulmonary shunt that may increase oxygen requirements. of predominantly passive exercise or no intervention, the passive exer-
Bed rest is an important risk factor for thromboembolic disease. cise group preserved fat-free mass, decreased IL-6 and increased IL-10
Thrombosis culminates from impaired blood flow, vascular injury, and levels compared with control patients who lost 7% of fat-free mass in the
coagulopathy (Virchow triad). Blood flow through extremities varies first 7 days following admission to the ICU. 40
with activity of muscles; therefore, inactivity may result in venous stasis. One study examined whether muscle wasting in critically ill patients
Furthermore, compression of veins from prolonged contact of limbs could be prevented with stretching alone. Continuous passive motion,
with the bed may also worsen stasis and potentially damage the vascular administered by a machine, for 3-hour sessions was applied over
endothelium. 7 days to one leg of five separate critically ill adults. Both lower extrem-
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More indolent effects include endocrinopathy and vascular dysfunc- ities received the usual passive ROM exercises from physiotherapists
tion. Studies of healthy volunteers undergoing 5 to 7 days of bed rest twice daily for up to 5 minutes. Percutaneous needle biopsies of both
demonstrated that insulin resistance occurs within days of beginning legs were obtained at baseline and after 7 days. In the muscles that
bed rest. The mechanism is unknown, but the effect is postulated to received continuous passive stretch, there was less reduction in muscle
33
be limited to skeletal muscle. Interestingly, insulin resistance occurs fiber cross-sectional area and protein per gram of wet muscle weight
34
commonly in critically ill patients who have no prior history of diabetes over the 7 days compared with the muscles that did not receive continu-
and insulin therapy in critically ill patients has been correlated with ous passive stretch. Clinical observation, however, suggests that more
improved neuromuscular outcomes. 35-37 Other metabolic derangements than simple passive movement should be done in order to help preserve
of bed rest measured in healthy subjects include increases in total cho- muscle strength.
lesterol and triglycerides. 33
The cardiovascular effects of deconditioning occur on both heart
tissue as well as the peripheral cardiovascular system. Orthostatic ACTIVE RANGE OF MOTION
ceptor dysfunction. Studies implicate that systemic vascular resistance ■ BARRIERS TO ACTIVE RANGE OF MOTION
intolerance is commonplace and believed to be the result of a barore-
increases after bed rest. For example, hyperemic responses in normal The primary purpose of physical therapy in the ICU is to engage the
subjects were significantly blunted after 3 to 5 days of bed rest, brachial alert patient, commence active ROM, and progress activity from bed
artery diameter decreased significantly and was associated with sig- exercises to transfers and early ambulation. However, early physical
nificantly decreased brachial artery flow and increased systolic blood therapy—or early mobility—in critically ill patients is a complex and

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