Applying a Continuous Passive Motion Device

Skill 9-12

Applying a Continuous Passive Motion Device

A continuous passive motion (CPM) is a motorized device that continuously passively moves a joint through a set degree of range of motion (Rex, 2018). The impact and benefit of CPM therapy is controversial, with studies providing conflicting evidence related to benefit of use (Chen et al., 2020; Wirries et al., 2020; Yang et al., 2019). However, CPM may be prescribed after total knee arthroplasty as well as after surgery on other joints, such as shoulders, elbows, or ankles. The degree of flexion and extension of the joint and the cycle rate (the number of revolutions per minute) are determined by the prescriber, but nurses place the patient in and out of the device and monitor the patient's response to the therapy.

Delegation Considerations

The application and removal of a CPM device is not delegated to assistive personnel (AP). The application and removal of a CPM device may be delegated to licensed practical/vocational nurses (LPN/LVNs). The decision to delegate must be based on careful analysis of the patient's needs and circumstances as well as the qualifications of the person to whom the task is being delegated. Refer to the Delegation Guidelines in Appendix A.

Equipment

CPM device
Single-patient-use soft-goods kit (sheepskin or padding)
Tape measure
Nonsterile gloves and/or other PPE, if indicated

Assessment

Review the health record and prescribed interventions for the prescribed degrees of flexion and extension. Assess the neurovascular status of the involved extremity. Perform a pain assessment. Administer the prescribed medication in sufficient time to allow for the full effect of the analgesic before starting the device. Assess for proper alignment of the joint in the CPM device. Assess the patient's ability to tolerate the prescribed treatment.

Actual or Potential Health Problems and Needs

Many actual or potential health problems or issues may require the use of this skill as part of related interventions. An appropriate health problem or issue may include:

Risk for impaired peripheral neurovascular function
Altered skin integrity risk
Knowledge deficiency

Outcome Identification and Planning

The expected outcomes to achieve when applying a CPM device are that the patient experiences increased joint mobility and does not exhibit atrophy or contractures, alterations in skin integrity, or impaired peripheral neurovascular function.

Implementation

Action	Rationale
1. Review the health record and prescribed interventions for the appropriate degrees of flexion and extension, the cycle rate, and the length of time the CPM is to be used.	Reviewing the health record and prescribed interventions validates the correct patient and correct procedure and reduces the risk for injury.
2. Obtain equipment. Apply the soft goods to the CPM device.	Equipment preparation promotes efficient time management and provides an organized approach to the task. The soft goods help to protect the skin that is in contact with the CPM device from friction and pressure.
3. Perform hand hygiene. Put on PPE, as indicated.	Hand hygiene and PPE prevent the spread of microorganisms. PPE is required based on transmission precautions.
4. Identify the patient. Explain the procedure to the patient.	Patient identification validates the correct patient and correct procedure. Discussion and explanation help allay anxiety and prepare the patient for what to expect.
5. Close the curtains around the bed and close the door to the room, if possible. Place the bed at an appropriate and comfortable working height (VHACEOSH, 2016).	Closing the door or curtains provides for privacy. Proper bed height helps reduce back strain.
6. Position the patient in the middle of the bed, with the head of the bed between 30 and 45 degrees. Make sure the affected extremity is in a slightly abducted position.	Proper positioning promotes correct body alignment and prevents pressure on the unaffected extremity.
7. Support the affected extremity, lift it up, and place it in the padded CPM device (Figure 1).	Support and elevation assist in movement of the affected extremity without injury.
8. Make sure the knee is aligned at the hinged joint of the CPM device. Check to confirm the padding is protecting any skin that is in contact with the CPM.	Proper positioning in the device promotes patient comfort and prevents injury and complications.
9. Adjust the footplate to maintain the patient's foot in a neutral position (Figure 2). Assess the patient's position to make sure the leg is not internally or externally rotated.	Adjustment helps ensure proper positioning and prevents injury.
10. Apply the restraining straps under the CPM device and around the leg. Check that two fingers fit between the strap and the leg (Figure 3).	Restraining straps maintain the leg in position. Leaving a space between the strap and leg prevents injury from excessive pressure from the strap.
11. Raise the bed rail closest to the CPM. Confirm that the foot of the bed is flat and the knee control option on the bed is locked. Place pillows if needed at the foot of the bed in front of the footboard on the CPM device to prevent the device from sliding away from the patient (Horse, 2010, as cited in Rex, 2018, p. 57).	A raised bed rail prevents the CPM device from falling off the bed. Locking the knee control prevents accidental raising of the lower part of the bed, displacing the CPM device and displacing the patient's knee (Horse, 2010, as cited in Rex, 2018, p. 57).
12. Explain the use of the STOP/GO button to the patient. Set the controls to the prescribed levels of flexion and extension and cycles per minute. Turn on the power to the CPM.	Explanation decreases anxiety by allowing the patient to participate in care.
13. Set the device to ON and start the therapy by pressing the GO button. Observe the patient and the device during the first three or four cycles; assess for any change in pain intensity rating or sudden breakthrough pain (Rex, 2018).	Observation ensures that the device is working properly, thereby ensuring patient safety and evaluates the patient's tolerance of the intervention.
14. Place the bed in the lowest position, with the side rails up. Make sure the call bell and other essential items are within easy reach.	Having the bed at the proper height and having the call bell and other items handy ensure patient safety.
15. Remove PPE, if used. Perform hand hygiene.	Proper removal of PPE reduces the risk for infection transmission and contamination of other items. Hand hygiene prevents the spread of microorganisms.
16. Check the patient's level of comfort and perform skin and neurovascular assessments at least every 4 hours or per facility policy. Assess for pinching of the leg by the device and that the straps are not too tight (Rex, 2018).	Frequent assessments provide for early detection and prompt intervention should problems arise.

Evaluation

The expected outcomes have been met when the patient demonstrated increased joint mobility and did not exhibit atrophy or contractures, alterations in skin integrity, or impaired peripheral neurovascular function.

Documentation

Guidelines

Document the time and date of application of the CPM, the extension and flexion settings, the speed of the device, the patient's response to the therapy, and your assessment of the extremity.

Sample Documentation

5/03/25

1430 Right knee incision clean and dry; dressing intact. Right toes pink and warm, with brisk capillary refill; equal to left. Pedal pulses present and equal bilaterally. CPM device applied with range of motion at 30 degrees of knee flexion, for 5 cycles/min for 30 minutes. Patient reports slight increase in pain from a rating of 4/10 to 5/10, but states, “I don't want anything for the pain right now.” Plan to reassess in 15 minutes and offer analgesic as prescribed.

—K. Dugas, RN

Developing Clinical Reasoning and Clinical Judgment

Unexpected Situations and Associated Interventions

Patient is prescribed therapy with a CPM device. After you initiate the prescribed flexion and extension of the joint, the patient reports sudden pain in the joint: Stop the CPM device. Check the settings to make sure the device is set correctly for the prescribed therapy. Assess the patient for other signs and symptoms and obtain vital signs. Perform a neurovascular assessment of the affected extremity. Notify the health care team of the patient's pain and any other findings. When therapy is resumed, evaluate the need for premedication with analgesics. Continue pain intervention with analgesics, as prescribed.

Special Considerations

General Considerations

The physical therapist will usually fit the CPM device to the patient. The thigh length on the CPM device is adjusted based on the distance between the gluteal crease and the popliteal space. The position of the footplate is adjusted based on the measurement of the leg from the knee to 14 in beyond the bottom of the foot.
Patient education should include the purpose, benefits, and possible complications of CPM therapy; the function of the device; and how to maintain safety precautions during CPM therapy (Rex, 2018).

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Skill 9-12