Guideline for Mobilising Critically Ill Patients



Guidance for the Mobilisation of Critically Ill Patients

Introduction

Research developments have lead to improvements in the diagnosis and management of critically ill patients. With these improvements, the survival rate of critically ill patients is increasing [6].

As impaired mobility is an almost inevitable sequelae for patients who are admitted to hospital with an acute life threatening illness, the physiotherapy management of these patients will often include treatment aimed at increasing mobility and independence [9].

The aims of mobilisation include:

• Improving respiratory function by optimising ventilation/perfusion matching, increasing lung volumes, and improving secretion clearance

• Reducing the detrimental effects of immobility

• Increasing levels of consciousness

• Increasing functional independence

• Improving cardiovascular fitness

• Improving psychological well being [8]

Additionally, for critically ill patients, mobilisation may reduce the incidence of respiratory complications, hasten recovery, decrease the duration of mechanical ventilation, and reduce the length of ICU or hospital stay [8].

For the purposes of this guideline, the generic term mobilisation may refer to any of the following:

• Active/active assisted limb exercises

• Turning in bed

• Bed → chair transfers via mechanical lifting machines or slide boards

• Lie → sit transfers

• Sitting at edge of bed

• Sit → stand

• Standing transfers

• Walking

Aim of Guideline

The aim of this guideline is to provide Greater Glasgow & Clyde Trust Physiotherapists with a reference tool regarding safety issues that should be considered prior to and while mobilising critically ill patients to minimise the risk of detrimental effects. The guideline covers safety factors intrinsic and extrinsic to the patient.

Medical Background

Prior to mobilisation, the patient’s current and past medical history should be obtained. This may provide practitioners with information that can help identify how well the patient is likely to tolerate mobilisation. In particular, it can indicate which system is likely to limit exercise tolerance and therefore provide clues as to what parameters to monitor during mobilisation [9].

The types of diagnoses that may affect a patient’s ability to tolerate mobilisation include:

• Cardiovascular disease – MI, cardiac surgery, angioplasty, angina, cardiac arrest, hypertension, peripheral arterial disease

• Respiratory disease – COPD, asthma, restrictive lung disease

• Cancer – bony metastases

• Metabolic – diabetes, renal failure, liver failure

• Neurological disorders – stroke, ataxia, MS

• Musculoskeletal disorders - osteoporosis

• Psychiatric conditions

In conjunction with a patient’s past medical history, the history of the patient’s presenting condition and current symptoms should also be obtained. This should also include a review of current medications, since drugs such as beta blockers, peripheral vasodilators and sedatives may affect a patient’s response to mobilisation or prevent mobilisation altogether. Information on a patient’s previous level of mobility and exercise tolerance will provide clues as to their pre-morbid function, the degree of deconditioning and the need for mobility equipment to assist in the safe mobilisation of the patient [9].

Cardiovascular Considerations

Heart Rate

The usual heart rate (HR) response to exercise in normal subjects is an incremental increase in HR, dependent on the person’s underlying fitness and the intensity of exercise [3]. Current literature suggests that mobilisations of any form result in an increase in HR, however, it is not clear by how much and the possible implications of such an increase.

There is little published clinical research concerning resting HR’s when determining the safety of mobilising critically ill patients before an intervention [9]. Calculations of age predicted maximal HR can aid the clinician in estimating the patient’s cardiac reserve [10]. The formula for calculating maximal HR is 220 – age of patient. It is recommended to express each patient’s resting HR as a percentage of his or her age predicted maximal HR. Stiller & Phillips suggest that in critically ill patients, it would seem appropriate to aim for an exercise HR either below or at the very low end of the range used for increasing the fitness of stable outpatients (60 – 90% of maximal HR). Therefore in critically ill patient’s, this would be approximately 50-60% of maximal HR.

For Example, a 45 year old patient:

Maximal HR = 220 – 45 = 175bpm

50-60% HR = 87 – 105bpm

As can be seen from the example above, it is likely that a large proportion of critically ill patients will have a resting HR already at or above the suggested exercise limits. In these circumstances, it is essential that the clinician consider HR in conjunction with other safety issues raised in this guideline, to support clinical decision making.

Blood Pressure

As with HR, the usual blood pressure (BP) response to exercise in normal subjects is an initial rise in systolic BP [5]. In contrast diastolic BP tends to remain stable or only slightly increase at higher levels of exercise intensity [3,5]. Several studies have documented an increase in BP of approximately 10% during active and/or passive limb movements in critically ill patients [7,11].

As with HR, there is no published data concerning safe levels of resting BP when deciding whether to mobilise critically ill patients. When interpreting BP prior to mobilisation to assess whether it is safe to proceed, the absolute values may not necessarily be indicative of haemodynamic stability for acutely ill inpatients [9]. Instead a recent change in BP (systolic, diastolic, or mean) is most relevant [4]. However an acute increase or decrease in BP, in the order of at least 20%, is indicative of haemodynamic instability and is likely to delay mobilisation [4].

If a critically ill patient requires inotropic medication (e.g. adrenaline or noradrenaline) to maintain adequate BP, in most cases, this is indicative of haemodynamic instability. Although it may be safe to gently mobilise patients who have stable BP on low levels of inotropes, in many instances where inotropes are required to maintain BP, mobilisation will have to be deferred [9].

Cardiac Status

The following are a list of cardiac conditions that should be considered as relative contra-indications to mobilisation in critically ill patients:

• Recent significant change in the resting ECG, suggesting significant ischaemia, recent myocardial infarction, or other acute cardiac event

• Unstable angina

• Uncontrolled cardiac arrhythmia causing symptoms or haemodynamic compromise

• Severe symptomatic aortic stenosis

• Uncontrolled symptomatic heart failure

• Acute pulmonary embolus

• Acute myocarditis or pericarditis

• Suspected or known dissecting aneurysm [3]

During mobilisation, ECG monitoring is strongly advised in critically ill patients as it provides an immediate measurement of HR and allows for the detection of arrhythmias. Additionally, all patients should be observed carefully for signs and symptoms of cardiac stress (e.g. clamminess, chest/arm/neck pain, and shortness of breath).

Respiratory Considerations

Oxygenation

When assessing a patient’s suitability for mobilisation, the inspired fraction of oxygen (FiO2) should be taken into account when interpreting PaO2 as this more accurately reflects oxygenation and thus the patient’s respiratory reserve [9]. The ratio of PaO2/FiO2 is a valid measure and easily calculable at the bedside. Various authors have suggested that a PaO2/FiO2 ratio of greater than 300 is a strong indicator for suitability for mobilisation. A ratio of 200-300 indicates marginal respiratory reserve and values less than 200 indicate virtually no respiratory reserve. Despite these recommendations, there is no published data to provide safety limits for interpreting values for PaO2/FiO2 prior to attempting mobilisation.

For Example:

|Patients |PaO2 |FiO2 |PaO2/FiO2 Ratio |Respiratory Reserve |

|Normally fit and well |100 |0.21 |476 |High |

|patient on room air | | | | |

|COPD patient on room air |60 |0.21 |286 |Low |

|Post-Op patient |90 |0.55 |164 |Very Low |

|spontaneously breathing | | | | |

|on face mask at 8L/min | | | | |

Patients should always be mobilised receiving the same FiO2 as is being delivered at rest, and preferably, with an oximeter to monitor SpO2 throughout. Stiller & Phillips 2003 suggest that a SpO2 of more than 90% is likely to reflect oxygenation that would allow for patient mobilisation. It is also recommended that SpO2 should be maintained at or above 90% during mobilisation to avoid pulmonary vasoconstriction. If a patient’s oxygenation deteriorates during mobilisation, the activity should be modified to a lower intensity that reduces the demand on the patient, or the FiO2 increased to improve oxygenation. If these measures do not improve oxygenation rapidly, mobilisation should be ceased.

Hypercapnia

While a chronically increased PaCO2 does not on its own affect the ability of acutely ill patients to mobilise, any associated decreased level of consciousness can obviously influence the patient’s ability to cooperate with mobilisation. An acute rise in PaCO2 is indicative of respiratory failure and, if accompanied by inadequate oxygenation, will most likely limit mobilisation [9].

Respiratory Pattern

As with oxygenation, observing a patient’s respiratory pattern can provide additional information regarding respiratory reserve [8]. This observation includes respiratory rate, the presence of asynchronous or paradoxical movement of the chest wall an abdomen, overactivity of the accessory muscles of respiration, and unduly prolonged expiration or wheezing [8].

If a patient is maintaining adequate oxygenation, but is only able to do this at the expense of an increased work of breathing, then mobilisation should be deferred, or caution taken when attempting mobilisation. Respiratory pattern should be monitored throughout the procedure.

Mechanical Ventilation

The need for a critically ill patient to be mechanically ventilated is not in itself a reason to prevent mobilisation. However, the need for high levels of ventilatory support to maintain adequate gas exchange indicates that the patient’s underlying respiratory reserve is likely to be poor.

It is recommended that the patient’s level of ventilatory support should be maintained throughout mobilisation, and the least demanding method of mobilisation should be used, at least initially [9].

Patients who are being weaned from mechanical ventilation are particularly vulnerable if mobilised during times of reduced ventilatory support. It is advisable to mobilise such patients during periods of higher ventilatory support to ensure that excessive demand is not being placed on the patient. Once mobilisation has been safely undertaken in this manner, the intensity can be increased to place higher demands on the patient or the same level of mobilisation can be attempted during periods of lower ventilatory support [9]

Haematological & Metabolic Considerations

Prior to mobilisation, the patient should be reviewed regarding haematological and metabolic considerations. This includes the following:

Haemoglobin (Hb)

The oxygen carrying capacity of the blood is proportional to the Hb level. Normal Hb ranges from 12-18 grams/dL. While there are no absolute lower values for Hb precluding mobilisation, an acute fall in Hb may delay mobilisation [9]

Platelet Count

Patients with a very low platelet count are at higher risk of microvascular trauma and bleeding which has the potential to result from mobilisation. A count of 20,000 cells/mm³ may be considered a safe lower limit [1].

White Cell Count (WCC)

An abnormally high (> 10,800 cells/mm³) or low (< 4,300 cells/mm³) WCC can indicate the presence of infection [1]. This in itself does not preclude mobilisation, but as infection can increase a patient’s oxygen utilisation, caution is required if undertaking activities that may further increase a patient’s oxygen demand [8].

Blood Glucose Level

Normally ranges from 3.8 – 5.8 mmol/L [12]. Mobilisation and exercise have the potential to increase any hypo / hyperglycaemia, which could lead to an altered level of consciousness and increased risk to the patient [9].

Subjective Considerations

In addition to the factors already discussed, there are numerous other factors that should be taken into account before mobilising patients to ensure the safety of the intervention to be carried out. These factors include:

• Appearance (cyanosis, clamminess, anxiety, and muscle bulk).

• Conscious state

• Level of pain (visual analogue scale)

• Rate of perceived exertion

• Shortness of breath (Borg scale)

• Level of fatigue

• Emotional status

Other Considerations

• Neurological status

• Orthopaedic conditions

• Skin conditions

• Deep vein thrombosis & pulmonary embolism

• Nutritional status

Attachments

During patient mobilisation, it is extremely important to ensure that all attachments are considered. Prior to mobilisation, seek advice from the patient’s nurse as to which attachments can be safely disconnected for the activity. It may also be beneficial to give individual clinicians roles during the mobilisation e.g. responsibility for the patient, ventilator tubing, catheter, etc.

Endotracheal (ET) or tracheostomy tube

Patients who are ventilated via an ET or a tracheostomy tube can be mobilised, however care should be taken to avoid dislodgement of the tube [2]. Excessive tube movement may traumatise the larynx or other areas of the upper respiratory tract [9].

Underwater sealed drain

When mobilising patients with an underwater sealed drain, care should be taken to ensure the tubing is not kinked or dislodged and that the drain remains below the level of the tube’s insertion in the chest [9].

Dialysis tubing

The mobilisation of patients receiving continuous haemodialysis may be dependent on the patient’s dialysis line site. Patients with a neck line can be sat up in a chair, but great care must be taken to avoid dislodgement of the dialysis line during the transfer. However, patients with a femoral line are often unable to be sat up as this may interfere with blood flow and lead to occlusion of the dialysis line.

Epidural

Patients with an epidural for pain relief can be mobilised once it has been ascertained that there is no motor (normal power in legs) or sympathetic block (BP within normal limits) [8].

Sengstaken tubes

Patients with bleeding gastroesophageal varices may be treated with a Sengstaken tube. Mobilisation of these patients should be avoided due to the potential risk of dislodgement of the tube and perforation of the oesophagus.

Environment

Prior to mobilising any critically ill patient, a thorough assessment of the environment should be carried out. This is to ensure that the environment is safe and uncluttered, patient attachments are sufficiently long and positioned appropriately, the bed height is optimal, and the appropriate equipment required for the mobilisation is at hand.

Staffing

When mobilising critically ill patients, it is essential that there are sufficient staff available to assist with the activity. Additionally, appropriate staff should be available to review the patient in the event of deterioration during mobilisation. Attention should also be given to ensure that the patient is kept informed about what is going to happen and when. Clear, concise, and calm instructions will ensure patient confidence and the overall safety of the mobilisation.

Selecting the Intervention

For critically ill patients, the most appropriate mode, intensity, frequency and duration of mobilisation will reliant on the patient’s degree of debilitation, current medical condition, dependency, and their response to previous mobilisation attempts. Initially mobilisation may start with tasks at a low intensity such as a bed exercises or mechanically assisted transfers to sitting out of bed. This may then be progressed to bed mobility and sitting on the edge of the bed. Once basic independence has been achieved and has been tolerated well by the patient, mobilisation can progress to the more complex tasks of standing and walking [8]. Keep in mind, that it is always far safer to increase the intensity of mobilisation slowly as each treatment is tolerated, rather than setting the patient back if too much is attempted too soon.

References

1. Braunwald E, Fauci A, Kasper D et al. Harrison’s principles of internal medicine 15th edition. New York; McGraw-Hill 2001.

2. Ciesla N, Murdock K. Lines, tubes, catheters and physiologic monitoring in ICU. Cardiopulmonary Physical Therapy Journal 2000; 11(1): 16-25.

3. Franklin B, Whaley M, Hawley E. ACSM’s guidelines for exercise testing and prescription 6th edition. Philadelphia: Lippincott Williams and Wilkins 2000.

4. MacIntyre N. Evidence-based guidelines for weaning and discontinuing ventilatory support. Chest: 2001, 120; 375-395.

5. MacArdle W, Katch F, Katch V. Exercise physiology 4th edition. Baltimore: Williams and Wilkins; 1996.

6. Morris P. Moving our critically ill patients: mobility barriers and benefits. Critical Care Clinics: 2007, 23: 1-20.

7. Norrenberg M, De Backer D, Moraine J et al. Oxygen consumption can increase during passive leg mobilisation. Intensive care medicine: 1995, 21: 177.

8. Stiller K. Safety issues that should be considered when mobilising critically ill patients. Critical Care Clinics: 2007, 23: 35-53.

9. Stiller K, Phillips A. Safety aspects of mobilising acutely ill inpatients. Physiotherapy Theory and Practice: 2003, 19: 239-257.

10. Stiller K, Phillips A, Lambert P. The safety of mobilisation and its effect on haemodynamic and respiratory status of ICU patients. Physiotherapy Theory and Practice: 2004; 20(3): 175-185.

11. Weissman C, Kemper M, Dansk M et al. Effect of routine intensive care interactions on metabolic rate. Chest: 1984; 86(6): 815-818.

12. Worthley L. Synopsis of intensive care medicine. Edinburgh: Churchill Livingstone; 1994.

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