Early Ambulation in Critical Care

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Introduction   

From the mid-1860s until 1950, bed rest was highly recommended to aid in recovery from various ailments. This common belief was not challenged until 1944, when physicians began to realize the deleterious effects bed rest had on virtually all systems of the body. Despite rising evidence, it took several years before the standard of care shifted. Now, bed rest is reserved for unique and serious medical conditions where no other options are available. Even in the hospital setting, mobilization is key to preventing further damage to the patient. Evidence shows that acute care hospitalizations have numerous negative impacts on health outcomes, especially for older adults. The most common adverse outcomes are loss of independence and chronic disability. This phenomenon is referred to as hospital-associated disability (HAD) [2]. 

Every year, approximately 5.7 million Americans are admitted into an intensive care unit (ICU) [8]. The disease processes or injuries that land the patient in the ICU are often severe and can result in the patient being bedbound for multiple days. In some studies, ICU patients were found to be in bed nearly 100% of the time they were there [3]. Consequently, patients are at risk of developing ICU-acquired weakness, among other impairments that reduce their functional capacity and quality of life. As patients endure additional problems, there is an increased need for more medical care, higher costs, and higher rates of mortality [8]. 

There is more emerging evidence that early mobilization for the ICU patient has numerous beneficial effects, including improved physical functioning, less risk of ICU-acquired weakness or delirium, fewer days on a ventilator, and an overall shorter hospital stay. Therefore, healthcare leaders and providers are more likely to advocate for early mobilization to improve patient outcomes [8]. 

The Basics  

Why is early ambulation in critical care important? 

Every day a hospitalized patient remains bedbound; their risk of mortality increases. Almost all ICU patients (80%) will develop some type of neuromuscular dysfunction, and about half will have physical, cognitive, and/or physiological impairments that prevent recovery to full independent living. The inability to return to baseline after an ICU stay is a condition known as post-intensive care syndrome [4].  

Patients who are at an increased risk of functional loss and other disabilities related to post-intensive care syndrome are struggling with cognitive impairment or dementia and reduced physical function at baseline, experience ICU-delirium, advanced age, comorbidities, or hospital readmission within the same year [13]. Assessing a patient’s ability to perform their activities of daily living or ADLs before ICU admission and afterwards is one objective method to determine loss of function. One of the most important ways to prevent post-intensive care syndrome is to mobilize an ICU patient as soon as possible [1].  

Quick Fact:  

It wasn’t until World War II that the bedrest protocols came into question. There were more wounded soldiers than beds available, so soldiers were forced to mobilize faster than what was traditionally accepted. It was observed that the soldiers who spent less time in bed recovered faster than those who were in bed for longer periods [11].  

Benefits vs Complications 

What are the benefits of early ambulation and potential complications if delayed? 

Early ambulation is an evidence-based preventative measure that has vast benefits. Some of the most notable include decreased incidence of delirium, reduced number of days on a ventilator, shorter length of hospital stays, and an overall higher functional status at the time of discharge [7]. The longer a patient is immobile, the higher the risk for muscle weakness, pressure sores, deep vein thrombosis, reduced joint mobility, and cognitive impairments. 

Deeper Dive into Complications 

Musculoskeletal 

For every day a patient does not walk, he will experience a 2-5% decline in muscle mass. Elderly patients (65 years and older) are at an even greater disadvantage as they are already experiencing age-related muscle loss. When critical illness is mixed into immobilization, the impact on muscle mass is accelerated due to the degradation of skeletal muscle protein stores [3]. Interestingly, much of our initial understanding of consequential impacts from bed rest comes from the aerospace industry. According to Brennan (2023), “Just like an astronaut exposed to a zero-gravity environment, when one does not use their bones or muscles to support locomotion, the bones and muscles undergo significant disuse atrophy” [3]. 

Cognition   

Walking and movement in general, are closely associated with social interaction. Immobility undoubtedly leads to social isolation and eventual depression. There is also a close link between immobilization and cognitive decline. Even brief periods of immobilization in the elderly have been found to double the risk of cognitive decline [3]. In the ICU setting, patients are often on multiple medications, such as opioids and sedatives, that can cause disorientation and confusion. The environment is full of loud noises and constant beeping that disturb sleep, and there is usually a lack of natural light. These factors, along with immobilization, are a recipe for ICU delirium and overall cognitive decline.  

Cardiovascular  

Immobilization and cardiovascular impairment are very well documented. Some of the most common cardiovascular complications include reduced blood volume, tachycardia, postural hypotension and deep vein thrombosis (DVT). During long periods of lying down, the delicate balance between the diuretic hormone, atrial natriuretic peptide, and the antidiuretic hormone or ADH are disrupted. This results in increased urine production and decreased blood volume. This change in blood volume has a direct impact on blood pressure [5]. 

The heart rate is also negatively impacted by immobilization. For every two days of rest, the resting heart rate increases by one beat per minute. Consequently, the diastolic and systolic ejection times shorten, resulting in reduced coronary blood flow [10].  

Now that you know that immobilization reduces blood volume and increases the resting heart rate, it is no wonder that postural hypotension is extremely common among immobile patients. In fact, it can take less than 24 hours of bed rest for a person to experience postural hypotension. Due to reduced blood volume, there is a disruption between the body’s baroreceptors, cardiac center, and vasomotor center. In a healthy, mobile person, the baroreceptors respond to a drop in blood pressure from standing by signaling to the cardiac center to increase cardiac output and blood pressure. While the vasomotor center is signaled to partially vasoconstrict in the lower limbs. When the blood volume is reduced, this chain of stimuli is impaired [14]. 

Deep vein thrombosis (DVT) is another likely problem patients can experience in the ICU when they aren’t ambulating. DVT’s form due to 1) venous stasis, 2) hypercoagulability, and 3) blood vessel damage. Bed rest increases the risk of these three problems developing and dramatically increases the risk of a DVT forming. If a DVT occurs, it is important to respond promptly, as it can progress to a pulmonary embolism, which can be fatal [6]. 

Respiratory 

The respiratory system is also vulnerable to the negative effects of immobilization. Lying supine restricts full movement of the rib cage due to the pressure of body weight. This reduces the tidal volume. The respiratory system also experiences reduced total lung capacity and residual volume from the increased blood volume and restricted movement of the chest [9]. Lastly, the lungs are more vulnerable to atelectasis and pneumonia due to decreased ventilatory volume and secretion clearance [1]. 

Important Guidelines 

What potential barriers exist that prevent early ambulation? 

Despite the obvious benefits of mobilizing an ICU patient as soon as possible, delays in ambulation still occur. Potential barriers have been closely examined to create solutions and implement clear guidelines.  

Some of the most common barriers include: 

• Poor resource allocation 
• Scarcity of resources 
• Lack of knowledge surrounding the impact of mobility on patient outcomes 
• Inefficiencies in interdisciplinary coordination 
• Patient acuity 
• No mobility protocol in place 

If there are not enough staff or assistive devices or there is poor coordination between nursing and physical therapy or occupational therapy, there are going to be delays in ambulation. If providers and support staff don’t have the knowledge surrounding the beneficial impact of mobility, then they are going to be less motivated to prioritize it [7]. 

Some more obvious barriers include the use of restrictive medical equipment such as intravenous (IV) lines, oxygen and mechanical ventilation. In these instances, patients are generally not encouraged to walk or it’s just simply not feasible. In 2008, the Center for Medicare & Medicaid Services addressed the high fall rates in hospitals by making reimbursement changes. The hypervigilant focus on falls may have discouraged providers from mobilizing patients in certain instances [3]. Patients have also reported feeling uncomfortable walking around in their gowns, worried about over-burdening nursing staff with requests to walk, and fearful of hurting themselves by pulling IV lines or sutures [3].  

Case Study #1 

Jennifer is a registered nurse in the cardiovascular ICU. Last night, a patient was admitted to her unit after he had a mitral valve repair. This morning, Jennifer is planning to get him up from the hospital bed into a chair. The patient is an elderly obese man, and Jennifer knows she is going to need an extra set of hands and a walker to assist him safely. When Jennifer seeks help, she realizes everyone is very busy and there is no one available on the unit. In addition, she can’t find a walker in her unit. She knows the walkers often get misplaced and put on other units. She doesn’t have time to look around for one. Jennifer’s other patient is in a more critical condition, so she decides to postpone getting this patient out of bed. 

What is mobility protocol?  

Mobility protocol is a set of guidelines unique to each specialty ICU. For optimal patient outcomes, you should get to know your hospital system’s mobility protocol as it can vary based on acuity level and patient needs. An example of a mobility progression algorithm includes four types of mobility progression: 1) dangle, 2) stand, 3) stand pivot/stand march, and 4) walking. A patient would progress through each type of mobility if the movement were well tolerated.  

To assess tolerance objectively, the mobility protocol should outline criteria such as the patient shows good tolerance if the heart rate stays within 20% of baseline or the oxygen saturation remains above 88% [7]. Patients may not participate in mobility progression if they are experiencing unstable arrhythmias, such as atrial fibrillation with rapid ventricular rate, are hemodynamically unstable, or have femoral lines [7]. It is important to know the unique exclusion criteria for each specialty ICU.  

There is still not enough research to determine the best systemic mobility assessment, but there are a couple of validated tools that should be used to evaluate a patient’s mobility. If patients aren’t assessed at the beginning of their hospitalization, no one will know how much they have regressed. One example is the Activity Measure for Post-Acute Care or AM-PAC 6-Clicks. This tool is a quick six-question form that is used to examine patients’ mobility limitations. A higher score is a good predictor that the patient will be discharged home, and a low score predicts a discharge to a setting that provides more support, such as a skilled nursing or inpatient rehabilitation facility [12].  

Case Study #2 

The unit Jennifer works on is very busy and often has very high acuity patients. Due to short staffing and a lack of assistive devices, Jennifer was not able to get her patient out of bed. The next morning, when she went to assess her patient recovering from the mitral valve repair, she realized he seemed confused and mildly agitated. Jennifer and another nurse assisted the patient to a dangling position on the bed, but he was very weak and unstable. Despite this, the nurses assist the patient to pivot into the chair. The patient sits in the chair, appearing very pale, and the monitor shows his blood pressure beginning to drop. There is no official mobility protocol in place, and no mobility assessment was initially performed on her patient. 

The Nurse’s Role and Other Interdisciplinary Involvement 

What is the nurse’s role in early ambulation in critical care? 

Based on recent research, improved long-term outcomes were found when mobilization was introduced within 48 hours of the patient’s admission to the intensive care unit [4]. LPNs and RNs are generally responsible for assisting the patient with ambulation, ensuring proper assistive devices are used as needed, and coordinating with other interdisciplinary teams such as physical therapy (PT) or occupational therapy (OT). 

Advanced practicing registered nurses (APRN) or nurse practitioners should ensure they are practicing within their scope of practice based on which state they practice in. Based on their scope of practice, the APRN is generally responsible for ensuring mobilization orders are placed and holding the nursing team and other staff accountable. 

All members of the care team should be familiar with their ICU’s mobility protocol. Effective coordination between interdisciplinary teams requires closed-loop communication and accurate documentation. The admitting registered nurse, APRN, or physical therapist should be conducting an initial mobility assessment upon admission to the ICU. It is also up to nursing staff to educate the patient and family in the importance of walking safely. It can be helpful to orient the patient to places in the unit that are safe to walk in and ensure assistive devices are ready to be used when needed [3].  

What other interdisciplinary teams should be involved?  

Mobility protocol should always have a multidisciplinary approach for best outcomes. Involvement should be expected from physicians, nurse practitioners, nurses, PT and OT, respiratory therapists, and the pharmacy. An effective mobility protocol should address any knowledge gaps that may exist amongst the team and occur in a setting that embraces quality improvement. ICUs that have a formal protocol in place are shown to have a larger impact on patient outcomes [4]. 

Case Study #3 

It is now the end of the day, and Jennifer’s patient has been diagnosed with ICU-delirium. Although the surgery went well, the complication of delirium puts the patient at risk for a longer ICU stay and further issues.  

Conclusion

Early ambulation in the ICU setting is an evidence-based preventative measure that has vast benefits. As discussed, some of the most notable benefits include decreased incidence of delirium, reduced number of days on a ventilator, shorter length of hospital stays, and an overall higher functional status at the time of discharge [7]. For intensive care units to be most likely to adhere to early ambulation, there must be a mobility protocol in place with which all staff are familiar.  

With nurses being at the center of patient care, it is up to them to ensure there is coordination among interdisciplinary teams and that patients are ambulating as able. It is important for nurses to be aware of the many barriers that exist and to collaborate with the care team to ensure that best practices are prioritized.  

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