There are currently few options for the prevention and/or treatment of ICUAW. During critical illness, exposure to hyperglycemia and certain medications (eg, corticosteroids and neuromuscular blocking agents) may be associated with the development of ICUAW. At present, the strongest evidence for the prevention of ICUAW is tight glycemic control with intensive insulin therapy, which may decrease neuromuscular abnormalities in critically ill patients who are mechanically ventilated for more than or equal to 7 days. However, the potential benefits of intensive insulin therapy should be carefully weighed against the possibility of serious hypoglycemia, as demonstrated in recent clinical trials.55,84 Finally, despite a strong evidence base, maintenance of electrolyte homeostasis (eg, phosphate, magnesium) and adequate nutrition to ameliorate muscle catabolism may be reasonable clinical recommendations for minimizing ICUAW.85
Beneficial Effects of Exercise in ICU
A potential therapeutic option to reduce ICUAW is avoidance of bed rest via EM in the ICU setting. EM in the ICU is a candidate intervention to improve muscle strength, physical function, and quality of survival.86 EM is the intensification and acceleration of the usual physical therapy (PT) that is administered to critically ill patients, along with additional novel concepts that include the mobilization of patients requiring mechanical ventilation and the use of novel techniques such as cycle ergometry and electrical muscle stimulation.86 EM is applied with the intention of maintaining or restoring musculoskeletal strength and function and thereby, potentially, improving functional, patient-centered outcomes.87
Usual Physical Therapy in ICU
The management of critically ill patients appears to vary widely within countries and internationally.88,89 This is partly due to cultural differences, funding differences (eg, staffing ratios of nurses to patient), and partly due to differences in medical management as a result of local practice. To date there is no published data comparing the practice of early mobilization in ICUs internationally. However, there are 2 multicenter point prevalence studies of EM in ICU that may be informative. The first studied all patients from 38 ICUs in Australia and New Zealand at a single time on a single day in 2009 and 2010.88 Of the 514 patients included, 45% were mechanically ventilated. Overall, mobilization activities were classified into 5 categories that were not mutually exclusive: 140 patients (28%) completed an in-bed exercise regimen, 93 (19%) sat over the side of the bed, 182 (37%) sat out of bed, 124 (25%) stood and 89 (18%) walked. Adverse events occurred on 24 occasions (5%). Importantly, none of the mechanically ventilated patients sat out of bed or walked on the day of the study. The main barrier to mobilization was that the patient was unconscious (20%) or deeply sedated (17%).
A similar study was conducted in 116 German ICUs including 783 mechanically ventilated patients.89 Overall, 185 patients (24%) were mobilized out of bed which was defined as sitting on the edge of the bed or a higher level of mobilization. Among patients with an endotracheal tube, tracheostomy, and noninvasive ventilation, 8%, 39%, and 53% were mobilized out of bed, respectively. This study identified cardiovascular instability (17%) and deep sedation (15%) as the main barrier to mobilization, however mobilization out of bed was not associated with a higher frequency of complications.
Clinical practice guidelines endorsed by the European Society of Intensive Care Medicine (ESICM) on the safety of EM have been published and serve as a guide to clinicians working in the ICU.90 Active mobilization of a critically ill patient, particularly if they require mechanical ventilation, involves a complex assessment that has not been standardized and may differ between ICUs and individual patients. In part this may be due to the heterogeneity of critical illness, the changing stability of the patient and the cointerventions; however it is also affected by the individual response to EM.91
The decision to actively mobilize a patient, both in bed and out of bed, should be made by the multidisciplinary ICU team, preferably during the morning rounds. The decision should include the individual assessment of the patient's past medical history and exercise tolerance, respiratory and cardiovascular stability over the previous 24-hour period, management of lines and tubes, consideration of orthopedic and neurologic conditions, medications that may affect the patients' safety during mobilization, and the available staff and equipment to ensure patient safety. Occasionally medical staff outside the ICU may need to be consulted about the safety of mobilization, for example in a polytrauma patient with lower leg injuries, an orthopedic surgeon may need to be contacted regarding the lower limb weight-bearing status if it is not clearly documented in the patient history.
Ideally, each ICU would formulate a protocol to guide EM, where decisions are predetermined about the safety criteria acceptable within that ICU to commence mobilization and the safety criteria to cease if the patient deteriorates during mobilization.
Cardiovascular stability is determined by assessing the heart rate and rhythm, blood pressure, requirement and dose of vasoactive or antiarrhythmic drugs, and other major cardiac conditions or support (eg, intra-aortic balloon pump, extracorporeal membrane oxygenation [ECMO]).90 The blood pressure and heart rate should be considered stable by the medical staff, with minimal variability (< 20%) over the preceding hours and stable requirements of vasoactive drugs. If there is any doubt about cardiovascular stability, the medical team should be consulted prior to mobilization.
Respiratory stability is determined by the respiratory rate and pattern, the fraction of inspired oxygen and the arterial oxygen concentration measured either with blood gases or a pulse oximeter and the ventilator settings if the patient is on mechanical ventilation, including the rate, pressure, volume, and requirement for positive end-expiratory pressure (PEEP). In general, the respiratory rate and oxygen requirements should not have increased in the preceding hours prior to mobilization and the patient should have a clear airway with minimal work of breathing.90 The oxygen saturation should be greater than 90% and the fraction of inspired oxygen 0.6 with PEEP less than 15 cm H2O. The respiratory rate should be less than 30 breaths/min.
Prior to each episode of mobilization, an appropriate ICU staff member should check the position of the artificial airway and ensure that the artificial airway is secure (ie, an orotracheal, nasotracheal, or tracheostomy tube). Additionally, if the plan is to move away from the bed, any supplementary gas supply required by the patient during mobilization should be available and there should be adequate reserve for the expected duration of the mobility session, and a little extra reserved for any unexpected additional requirements.
Ideally, prior to mobilization, the patient is awake, calm, and able to follow instructions. This can be assessed with standardized tools, such as the Richmond Agitation and Sedation Scale (RASS), where a score of –1 to +1 is ideal. Delirium is common in the ICU and can also be assessed using the Confusion Assessment Method for the ICU (CAM-ICU). Other neurologic precautions for EM include active treatment for intracranial hypertension, craniectomy, open lumbar drains, spinal precautions, or the presence of an acute spinal injury.
Medical Conditions—Patients should also be assessed with regards to oxygen carrying capacity (Hb > 7 g/dL and stable), white cell and platelet count, deep vein thrombosis or pulmonary embolus, body temperature, unstable fractures, skin grafting, and open surgical wounds. If there is any doubt about the safety of mobilization, the senior consultant or surgeon should be asked to make a final decision prior to commencing EM.
Staffing—There must be adequate trained staff and equipment to ensure safe mobilization of an ICU patient. In the case of a mechanically ventilated patient, one person should always be designated to ensure the security of the airway during mobilization. The patient should be assessed for strength prior to mobilizing out of bed, for example using the MRC manual muscle test, and if there is significant weakness the patient may not be strong enough to mobilize against gravity or they may require specific equipment designed to assist with EM. This may include a hoist, standing lifter or a walking frame designed to include a pole (to attach intravenous fluids), and a stand for the mechanical ventilator and oxygen tank (Figure 14–1).
A custom made walking frame on wheels, including 2 poles for intravenous fluids, a stand for the mechanical ventilator, and a frame to hold the oxygen cylinder.
Other Lines, Drains, and Attachments—Each ICU may differ in its policy regarding attachments that are safe for mobilization, or attachments that are contraindicated for mobilisation. Discussion about the safety of various patient lines and attachments must be considered on an individual basis. There is some evidence that femoral catheters, including femoral catheterization for hemofiltration, should not be a contraindication to EM in the ICU.92 Similarly, some extracorporeal devices are considered safe for EM with adequately trained staff conducting the activities.93
In a recent systematic review of physiotherapy in intensive care, 17 observational studies of EM reported outcomes regarding feasibility, safety, and physiologic effects.91 Mobilization activities were reported as both safe and feasible, with the frequency of serious adverse events reported to be less than or equal to 1%. There were occasional short-term physiologic changes associated with EM that requires careful assessment throughout the mobilization activity.
Clinical Evidence—Early mobilization in ICU is an emerging new focus of intensive critical care research, representing a potentially lower-cost, high-impact intervention. However, there are few RCTs evaluating its efficacy.
Three RCTs94,95,96 and a number of observational studies97,98,99,100,101,102 have provided data on the safety and preliminary efficacy of the concept of mobilizing patients dependent on ventilatory support. In the first observational study, the authors described 1449 activity events in 103 patients. Overall, 53% of these events included ambulating patients that were dependent on positive pressure ventilation via an endotracheal tube or tracheostomy; there was less than 1% adverse events related to EM. This treatment was resourced from within the existing ICU staff structure, including ICU nurses, technicians, physical therapists (PTs), and respiratory therapists. In a further study, the same authors describe a before-and-after cohort study in 104 patients with respiratory failure who were transferred from another ICU to their respiratory ICU. Transfer to the study respiratory ICU with a culture of EM increased the probability of ambulation (P < 0.0001) during ICU stay.
Schweikert and colleagues reported findings from a prospective, outcome assessor-blinded, randomized trial of early physical therapy (PT) and occupational therapy (OT) from two centers in the USA.95 In this study, patients who were mechanically ventilated for less than 72 hours and expected to stay ventilated in the next 24 hours were randomized either to an EM protocol which progressed from passive range of motion (PROM), active range of motion (AROM), bed mobility, sitting balance, standing, standing transfers, and gait reeducation during sedation interruption, or a control group which underwent PT and OT as prescribed by standard care. This trial demonstrated safety and feasibility for EM, as well as improved functional outcomes with early intervention.