Importance of early mobilization in critically ill patients

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Physiotherapists are trained to mobilize patients in Intensive Care Unit (ICU), but patients are seldom mobilized either due to nervousness, or being apprehensive of mobilizing these patients. This article aims to highlight the benefits of early mobilization, and to encourage the ICU staff and physiotherapists to do their best for patients and get them moving.

Introduction

Critically ill patients are treated in ICU until they are deemed stable enough to be transferred to a ward. This may take a few days, weeks, or months. In their time in the ICU, they are often ventilated, sedated, and/or immobile. It is good to concentrate on their immediate recovery from  acute condition, because the treatment received during ICU stay will have a significant impact on their long-term outcomes. Many are left weak and emaciated from prolonged bed rest and immobility.1 This phenomenon is known as “ICU-acquired weakness.

 

For a patient to be diagnosed with ICU-acquired weakness, they need to meet the following criteria:

  • Weakness associated with critical illness
  • Weakness is bilateral, flaccid and involves both proximal and distal muscles, but spares cranial nerves
  • Medical research council sum score <48
  • Prolonged mechanical ventilation
  • Other causes of weakness have been excluded.2,3

 

It is possible that Hippocrates was the first to recognize the potential harm prolonged bed rest can have on a patient, noting that it has a negative effect on bone, muscle and teeth.4 Patients who are mechanically ventilated for more than seven days are 25-60% more likely to develop ICU-acquired weakness.2 There is also a strong correlation between long-term ventilator dependency and generalized weakness.5 This weakness results in prolonged hospitalization and/or a decreased quality of life. A study reported that patients discharged post intubation after Acute Respiratory Distress Syndrome were significantly affected 1 year after discharge, and some of these effects were still evident after a 5 year follow-up.3 Weakness is not the only negative effect of an ICU stay, psychological symptoms such as stress, depression, confusion, anxiety and forgetfulness are also common.4 Inactivity affects the brain, skeletal muscle, skin, cardiovascular and pulmonary systems.6,7  With all the above negative effects mentioned, it is clear that we need to find a way to minimize them by early mobilization intervention.

It is important to understand the role of early mobilization of a patient. Early mobilization should benefit the patient, should be safe, it should reduce the length of stay in ICU and should reduce the readmission rate back into ICU.2 One important thing to remember is that the mobilization done should be sufficient to elicit a physiological response.

Traditionally, rehabilitation is commenced after ICU discharge, but maybe, we should consider early mobilization as pre-habilitation rather than rehabilitation. Early mobilization should begin within 24hours of admission into an acute setting.8 We are after all, trying to prevent rather than treat ICU-acquired weakness.

Cardiac effects

When humans are healthy, they spend up to 16 hours a day upright (either sitting or standing), but during prolonged ICU admission, the patients hardly achieves this. With a decrease in the effects of gravity on the fluids in the body, there is a general shift of fluids up, toward the abdomen and thorax. This leads to changes in pressures experienced by the veins, arteries and heart, which in-turn disturbs the hormone balance that regulates the kidneys. This disruption causes the kidneys to re-absorb less fluid, and excrete more, which could lead to dehydration and a decrease in blood volume if not monitored.4

To ensure that venous return is adequate, the healthy/active body uses the lower limb muscles as a muscle pump, which forces blood against gravity towards the heart. During prolonged bed rest, these muscles are less active, therefore less blood is pumped to the heart using this mechanism. This inactivity leads to muscle atrophy, which makes the muscle pump less effective at the time and also post bed-rest.4

The decrease in blood volume, and decrease in venous return cause a decrease in stroke volume. To maintain the cardiac output, the heart rate needs to increase. And increase of ±10 beats per minute is usually experienced. The cardiac muscle is put under less stress due to the lower stroke volume, and therefore starts to atrophy, which is termed cardiac de-conditioning.4

Postural hypotension is one of the first complications noted after bed-rest. This phenomenon can be observed after as little as 20 hours of bed-rest. Postural hypotension describes the condition when a person sits/stands up from supine and feels dizzy or light-headed and it is caused by a sudden drop in arterial pressure as gravity takes the blood toward the lower limbs.4 Another complication of immobilization is the risk of deep vein thrombosis (DVT) which in itself has its own risks of pulmonary embolism and possibly stroke.7

Respiratory effects

Most patients confined to bed are nursed in supine position. This causes the abdominal contents to push up against the bottom of the diaphragm, making inhalation harder. The residual volume (volume of air that remains in the lungs after a full expiration) is decreased in a supine position which decreases the amount of oxygen available for perfusion.4

When a person is healthy and active, the cilia in the bronchus mobilizes secretions up and out the lungs, where they are swallowed and any infectious cells destroyed by stomach acid. There is a tendency for sputum to ‘pool’ when a person is supine for an extended period of time. This creates the perfect environment for bacterial growth.4

Another complication associated with mechanical ventilation is ventilator associated pneumonia.  This occurs in 9 to 27% of patients who are ventilated, and it has a high mortality rate (33 to 55%).6

Physiotherapy aims to increase ventilation and perfusion by increasing lung inflation, improving secretion clearance and respiratory muscle function.4 Early mobilization reduces pneumonia and other respiratory complication, and likely improves ventilation, perfusion, lung compliance and secretion clearance.7

Skeletal muscle effects

One of the most drastic changes noted in immobile patients, particularly those who are ventilated is the decline in skeletal muscle mass, known as muscle atrophy. Some articles have reported as much as a 25% loss in peripheral muscle strength within four days of being on mechanical ventilation and others describe how muscle can atrophy at a rate of 5% per day.6,8 Skeletal muscle atrophy is most noticeable in the first two to three weeks of immobility.

Atrophy and associated weakness of skeletal muscle leads to persistent functional disability in patients post discharge. It also decreases the amount of tissue between the bony points and the bed, therefore increasing the chance of pressure sores.8

Gastrointestinal system

A supine position decreases the rate at which food passes down the oesophagus, and decreases gastric emptying by 66% when compared to persons in an upright position. This results in food passing through the colon slower, increasing the amount of water that is reabsorbed, thereby increasing the chance of constipation. In Supine, there is also no pressure exerted by the stool on the anal sphincter and the urge to defecate is drastically reduced. Many of the patients in the intensive care setting receive opioid based analgesia which slows down the gastrointestinal tract mobility which again leads to constipation.9

Nervous system

When a patient is confined to bed, they are not stimulated very much and this is paramount to sensory deprivation.9 When there is relatively low external stimulation, the patient usually turns their attention to internal stimulation and may feel more pain and discomfort than usual. Inactivity causes a change in the neurotransmitter concentrations in the body, increasing aggression, reducing pain threshold and insomnia.9  Critical illness polyneuropathy is a long term effect of extended immobilization due to sepsis, septic shock or multi-system organ failure, and this is caused by degeneration of the axons affecting motor neurons more than sensory nerves.3

Integumentary system

The skin is particularly sensitive to immobilization. There are 4 areas on the body that are particularly sensitive to the pressure; heels, sacrum, scapula spine and the back of the head. The skin is usually thin over these bony protrusions and is prone to bed/pressure sores after prolonged immobilization. Bed/pressure sores occur as a result of pressure occluding the capillaries in the area causing death of the tissue. Pressure sores can account for up to 8% of deaths.10

What is early mobilization?

Early Mobilization is the intensification and early application (within the first 2 to 5 days of critical illness) of physical therapy that is administered to critically ill patients.”2

Mobilization comes in many forms, namely; transfers from bed, active and/or passive mobilization of limbs in bed, active positional changes in bed, sitting over the side of the bed, standing next to the bed, walking on the spot, and walking with or without support.1 There is only very weak evidence to support the use of passive movements as a treatment option, but doing something is better than nothing.2 However, a study cited that passive movements of healthy patients left them with decreased stiffness and more muscle extensibility.1 The following techniques where used in the studies; sitting over the side of the bed, passive range of motion, marching on the spot, specific stretching and strengthening, active and passive transfers, standing, sitting in a chair, balance training and walking. Patients who are acutely ill, sedated, or are uncooperative can be treated with passive range of motion, splinting, stretching, positioning or electrical muscle stimulation. Patients who are awake, cooperative and stable can be treated with mobilization to the edge of the bed, sitting in a chair, strengthening exercises, cycling and or walking where possible regardless of whether or not they are ventilated.1

A study in which critically ill patients where made to do 30-40min supine cycle ergometer sessions (both active and passive), showed a significant increase in their 6-min walk test distance post ICU discharge and their quadriceps muscle size was largely preserved.2

Another method of early mobilization involved transcutaneous electrical muscle stimulation (TEMS) or neuromuscular electrical stimulation (NMES). Randomized control trials have produced conflicting results and therefore there is no solid evidence to prove it is effective as a treatment option. However, it may suggest that TEMS be used in conjunction with active movements in wider early mobilization program/protocols.2 On the other hand, it was also suggested that the use of TENS is better than doing passive movements as it may prevent inactivity muscle atrophy and critical illness neuropathy.1

Who can be mobilized, and to what extent?

Not every patient can be mobilized to the same extent, so we need to have a method to decide to what extent we are able to safely mobilize each patient. It is also important that we progress the patients’ mobilization as their condition allows. Patients unable to co-operate may require passive mobilization, which may include mobilizing a patient with a hoist to sitting in a chair if they are stable enough to do so.11 The algorithm in Figure 1 allows the multidisciplinary team (MDT) to decide how and when to mobilize the patient and also to what extent they can safely mobilize the patient. During the process of mobilizing the patient it is imperative to monitor and re-evaluate the patients condition in order to safeguard the patients safety.  In figure 1, there are six levels of mobilization, each level contains a progression of mobilization when compared to the previous level.

In Level 0 the MDT assesses the patients’ stability with the criteria included. If the patient is stable, the MDT decide if the patient is awake and alert, if the patient is not, then a “sedation vacation” should be considered. If this is not possible, the MDT would implement Level 1 mobilization techniques. Throughout this process the safety concerns need to be addressed so as to protect the patient. Once safety concerns are addresses, the MDT may implement Level 2 mobilization techniques. During the this level, passive transfers to a chair should be considered, or changing the bed to a chair if it is not possible (some ICU beds have the ability to adjust to a chair). During each step, the patient needs to be constantly monitored so that the exercises can be progressed or regressed depending on the patients ability to cope. To be able to progress from level 2 to level 3 the patient must be able to sit unsupported and have Oxford 3/5 strength in the lower limbs. During level 3 the exercises concentrate on building strength to facilitate independent mobilization. Once the patient has progressed to standing with the assistance of 2 people, we can progress to level 4 mobilization where we would like the patient to walk with a frame before progressing to level 5. Here, the patient will progress to walking with minimal assistance.

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Conclusion

Implementation of an early mobilization protocol is only possible if the whole MDT is involved and buys into it.7 The protocol should be progressive in its implementation and should be limiting via constant re-evaluation of the patient. Recent studies have shown that early physical therapy and mobilization of patients, including ventilated patients, can be done safely, and is effective in improving long-term outcome.2,3,5,7 It reduces delirium, improves functional outcomes, reduces mortality, and also length of stay in hospital.1,11  Six studies showed that patients involved in early mobilization programs had a decreased length of stay in hospital (regardless of admission condition) than those in the control groups.3,8 One article noted that ventilated patients are seldom mobilized, and this might be due to fact that it is more difficult, time consuming and there is always the chance of unplanned extubation.11 In order to mobilize a patient safely, certain criteria need to be met. One study reported a decrease in complications and a 50% decrease in re-intubation rate following early mobilization.7 Early mobilization protocols improve the functional status of patients after ICU admission.3

The proposed algorithm will make decision making consistent and improve the functional status of the patients upon discharge from ICU.

 

REFERENCES

1. Gosselink R, Clerckx B, Robbeets C, Vanhullenbusch T, Vanpee G, Segers J. Physiotherapy in the intensive care unit. Netherlands Journal of critical care. 2011 April; 15(2): p. 68-75.
2. Hodgson C, Berney S, Harrold M, Saxena M, Bellomo R. Clinical review: Early patient mobilization in the ICU. Critical care. 2013; 17(207).
3. Schweickert W, Kress J. Implementing early mobilization interventions in mechanically ventilated patients in ICU. Chest. 2011; 140(6).
4. Knight J, Nigam Y, Jones A. Effects of bedrest 1: cardiovascular, respiratory and heamatological systems. Nursing times. 2009; 105: p. 21.
5. Griffiths R, Hall J. Intensive care unit-acquired weakness. Critical care Medicine. 2010; 38: p. 779-787.
6. Zomorodi M, Topley D, McAnaw M. Developing a mobility protocol for early mobilization of patients in a surgical/trauma ICU. Critical care research and practice. 2012;: p. 1-10.
7. Clark D, Lowman J, Griffin R, Matthews H, Reiff D. Effectivemess of an early mobilization protocol in a trauma and burns intensive care unit: A retrospective cohort study. Physical therapy. 2013 February; 93(2): p. 186-196.
8. Pashikanti L. Impact of early mobilization protocol on the medical-surgical inpatient population. Clinical nurse specialst. 2012;: p. 87-94.
9. KNight J, Nigam Y, Jones A. Effect of bedrest 2: gastrointestinal, endocrine, renal, reproductive and nervous system. Nursing times. 2012; 105: p. 22.
10. Teasell R, Dittmer D. Complications of immobility and baed rest. Canadian family physician. 1993; 39: p. 1440-1446.
11. Green M, Marzano V, Leditschke I, Mitchell I, Bissett B. Mobilization of intensive care patients: a multidisciplinary practicle guide for clinicians. Journal of Multidisciplinary Healthcare. 2016; 9: p. 247-256.

Opinions expressed by physiogramworld contributors are their own.

Andrew Havemann

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