Invasively ventilated patients	Non-invasive/self-ventilating patients
Manual hyperinflation (MHI)	Active cycle of breathing technique (ACBT)
Suction	Manual techniques
Manual techniques	Positioning
Positioning	Intermittent positive-pressure breathing (IPPB)
Mobilization/rehabilitation	Continuous positive airways pressure (CPAP)
	Non-invasive ventilation (NIV)
	Nasopharyngeal/oral suction
	Positive expiratory pressure (PEP) mask, flutter valve
	Mobilization/rehabilitation

MANUAL HYPERINFLATION

In this technique a self-inflating circuit is used to deliver a volume of gas 50% greater than tidal volume (V_T) via an endotracheal or tracheostomy tube. An augmented V_T may recruit atelectatic lung secondary to reduced airflow resistance and enhanced interdependence via the collateral channels of ventilation.³ Bronchial secretions may be mobilised by the increased expiratory flow rate and/or stimulation of a cough.⁴ However, ventilator hyperinflation, the delivery of an augmented V_T via the ventilator, has been shown to be as effective in the removal of secretions and maintenance of static lung compliance as conventional manual hyperinflation (MHI).⁵ This may also avoid cardiopulmonary instability associated with ventilator disconnection and loss of positive end-expiratory pressure (PEEP). In an emergency situation an Ambu-bag and facemask can be used to perform MHI in the self-ventilating patient. However, an alternative technique such as intermittent postitive-pressure breathing (IPPB) should be considered when an augmented V_T is required during a therapeutic intervention (Table 5.2).

Table 5.2 Potential advantages and complications of manual hyperinflation

Potential advantages

Reversal of acute lobar atelectasis³

Alveolar recruitment via channels of collateral ventilation³

Improvement in arterial oxygenation

Mobilisation of secretions and contents of aspiration⁵

Improved static lung compliance⁵

Effectiveness may be increased when combined with appropriate positioning and manual techniques¹

Potential complications

Absolute contraindications include undrained pneumothorax and unexplained haemoptysis

Cardiovascular and haemodynamic instability⁶

Loss of PEEP, inducing hypoxia and potential lung damage. This can be minimised by incorporating a PEEP valve into the circuit of a ‘PEEP-dependent’ patient

Risk of volutrauma, barotrauma and pneumothorax,⁷ which can be reduced by including a manometer in the circuit

Risk of increased intracranial pressure

Increased patient stress and anxiety

PEEP, positive end-expiratory pressure.

RECRUITMENT MANOEUVRES

Recruitment manoeuvres may be employed to reverse hypoxaemia in patients with acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). A recruitment manoeuvre involves a transient increase in transpulmonary pressure in an attempt to reinflate and maintain atelectatic lung units.⁸ No standard approach exists; however, common options include: the application of incremental levels of continuous positive airways pressure (CPAP) with no tidal excursion; incremental increases in PEEP with additional V_T; and the application of intermittent larger ‘sigh’ breaths. In randomised studies, although recruitment manoeuvres may transiently improve oxygenation, there is as yet no proven outcome benefit.⁹

SUCTION

Suction is used to clear secretions from central airways when a cough reflex is impaired or absent. A suction catheter is passed via an endotracheal or tracheostomy tube or via a nasal/oral airway to the carina, and this may stimulate a cough in a non-paralysed patient (Table 5.3). The catheter is pulled back 1 cm before suction is applied on withdrawal. The suction catheter diameter should not be greater than 50% of the diameter of the airway through which it is inserted as large negative pressure can be generated intrathoracically without air entrainment. The use of suction following effective MHI optimises removal of secretions.¹⁰ Instillation of normal saline prior to suctioning remains controversial; however, it may stimulate a cough, maximising secretion mobilisation and clearance.

Table 5.3 Potential advantages and complications of suction

Potential advantages

Stimulation of a cough when reflex is impaired by mechanical stimulation of the larynx, trachea or large bronchi

Removal of secretions from central airways when cough is ineffective or absent

Potential complications

Tracheal suction is an invasive procedure and should only be undertaken when there is a clear indication

Absolute contraindications to suctioning are unexplained haemoptysis, severe coagulopathies, severe bronchospasm, laryngeal stridor, base-of-skull fracture and a compromised cardiovascular system

Hypoxaemia can be induced secondary to suctioning. This can be limited by pre- and postoxygenation

Cardiac arrhythmias may be more common in the presence of hypoxia

Tracheal stimulation may produce increased sympathetic nervous system activity or a vasovagal reflex producing cardiac arrhythmias and hypotension

MANUAL TECHNIQUES

POSITIONING

A simple change of position can have a profound effect on cardiopulmonary physiology ^14,¹⁵ (Table 5.4). As such, positioning is commonly utilised to achieve several different goals: drainage of secretions using gravity-assisted positioning (GAP), reduction of the work of breathing/breathlessness or to optimise V/Q matching.

Table 5.4 Potential advantages and complications of mobilisation ¹⁴

Potential advantages
Positioning supine to upright	Mobilisation
↑ Lung volumes	↑ Ventilation
↑ Lung compliance	↑ V/Q matching
↓ Airway closure	↑ Recruitment of lung units
↑ PaO₂	↑ Surfactant production/distribution
↓ Work of breathing	↑ Mobilisation of secretions
↑ Mobilisation of secretions	↑ Cardiopulmonary fitness and exercise capacity
Potential complications
Cardiovascular/neurological/haematological instability
Increased oxygen/ventilatory requirement

(Adapted from Dean E: The effects of positioning and mobilization on oxygen transport. In: Pryor JA, Webber BA (eds) Physiotherapy for Respiratory and Cardiac Problems, 2nd edn. Edinburgh: Churchill Livingstone; 1998: 125.)

GRAVITY-ASSISTED POSITIONING

GAP facilitates the removal of excess bronchial secretions by positioning a specific bronchopulmonary segment perpendicular to gravity (Table 5.5). This technique is not used in isolation but in conjunction with augmented V_T, via the ventilator, MHI or ACBT in a spontaneously breathing patient. An individual position exists for each bronchopulmonary segment based on the anatomy of the bronchial tree;¹⁶ however, these may need modification in the ICU setting.

Table 5.5 Potential advantages and complications of gravity-assisted positioning (GAP)

Potential advantages

Maximises removal of excess bronchial secretions when combined with active cycle of breathing technique

Allows accurate treatment of specific bronchopulmonary segments

Self-treatment can be included in a home programme on discharge

Potential complications

Positions need modification when used in the presence of cardiovascular/neurological instability, haemoptysis or gastric reflux

REDUCTION OF THE WORK OF BREATHING

A reduction in the work of breathing/breathlessness can be achieved by putting a patient in a position that optimises the length–tension relationship of the diaphragm, promotes relaxation of the shoulder girdle and upper chest and facilitates the use of breathing control.¹⁷ This approach to positioning is particularly effective when used in conjunction with non-invasive ventilation (NIV). Adequately supported high side-lying is a useful position to promote relaxation of the breathless patient. In addition, it can discourage the overuse of accessory muscles of respiration, which may reduce energy expenditure. Some patients prefer forward lean-sitting with their arms placed in front of them on a high table. In this position the length–tension relationship of the diaphragm is optimised secondary to forward displacement of the abdominal contents.

VENTILATION/PERFUSION

Appropriate positioning of a patient can maximise V/Q.¹⁸ In the self-ventilating adult, V/Q matching increases from non-dependent to dependent areas of lung.¹⁹ However, in adults receiving positive-pressure ventilation lung mechanics are altered, producing V/Q inequality. In this situation non-dependent areas of lung are preferentially ventilated while dependent regions are optimally perfused; as such, a regular change of position is recommended.

In an extreme form prone positioning has been used to improve refractory hypoxaemia in patients with ALI/ARDS. The mechanisms behind these improvements are complex, but likely centre around a combination of a redistribution of some pulmonary perfusion together with a more homogeneous distribution of ventilation, leading to improved V/Q matching. Although prone positioning improves oxygenation in 70% of patients with ALI/ARDS, its role in improving outcome remains controversial.²⁰

ACTIVE CYCLE OF BREATHING TECHNIQUE

The ACBT is a cycle of breathing exercises used to remove excess bronchial secretions (Table 5.6). The cycle can be adapted for each patient according to existing underlying pathology and presenting clinical signs. It consists of:

• breathing control × 4–6 breaths

• normal tidal breathing using the lower chest

• minimising the use of accessory muscles of respiration

• promoting relaxation

• lowering thoracic expansion × 4–6 breaths

• with/without an inspiratory hold

• forced expiration technique

• expiration with an open glottis (‘huff’), combined with breathing control

Table 5.6 Potential advantages and complications of active cycle of breathing technique (ACBT)

Potential advantages

Mobilises and clears excess bronchial secretions^21,²²

Improves lung function²³

Minimises the work of breathing

Individual components of the cycle can be utilised/emphasised to target specific problems

Can be used in combination with other manual techniques, gravity-assisted positioning, V/Q matching, positioning to reduce breathlessness and during activities such as walking

Self-treatment can be included in a home programme

Potential complications

Without adequate periods of breathing control, bronchospasm and desaturation can occur

Poor technique can lead to ineffective treatment and unnecessary energy expenditure

Although mainly used in the self-ventilating patient, alert, cooperative, ventilated patients can participate with this technique. The ACBT can be delivered via MHI in sedated and ventilated patients requiring mobilisation of secretions and airway clearance.

MECHANICAL ADJUNCTS

INTERMITTENT POSITIVE-PRESSURE BREATHING

IPPB is a patient-triggered, pressure-cycled mechanical device mainly used in self-ventilating patients to increase ventilation, mobilise bronchial secretions and re-expand lung tissue by augmenting V_T ²⁴ (Table 5.7). Positive airway pressure is maintained throughout inspiration. Expiration is passive. IPPB requires constant adjustment of pressure and flow rates and careful patient monitoring to maintain effectiveness and cooperation. Effectiveness is increased when used in conjunction with positioning, ACBT and manual techniques²⁴ (Table 5.8).

Table 5.7 Site and action of intermittent positive-pressure breathing (IPPB), continuous positive airways pressure (CPAP) and non-invasive ventilation (NIV)

Table 5.8 Potential advantages and complications of intermittent positive-pressure breathing (IPPB), continuous positive airways pressure (CPAP) and non-invasive ventilation (NIV)

Potential advantages

Improves lung volumes

Improves gaseous exchange

Decreases the work of breathing

IPPB and NIV can mobilise excess bronchial secretions by improving V_T

IPPB and NIV can improve lung and chest wall compliance

CPAP reduces left ventricular afterload by reducing the transmural pressure gradient

Patients can be mobilised while on CPAP and some modes of NIV. Alteration of ventilator settings might be indicated to maximise patient potential/exercise tolerance during treatment

Settings can be adjusted to augment physiotherapy intervention, e.g. increased inspiratory positive airway pressure to assist removal of secretions

Potential complications

Absolute contraindications include severe bronchospasm, undrained pneumothorax, pneumomediastinum, unexplained haemoptysis and facial fractures. Use with care in pre-existing bullous lung disease

Haemodynamic/neurological instability

Risk of decreased urine output with CPAP and NIV

Risk of carbon dioxide retention with CPAP

Risk of aspiration

IPAP, Inspiratory positive airway pressure.

CONTINUOUS POSITIVE AIRWAYS PRESSURE

CPAP maintains a positive airway pressure throughout inspiration and expiration. It is used in both intubated and self-ventilating patients to increase/normalise functional residual capacity (FRC) via recruitment of atelectatic lung. Clinically increased FRC is associated with improved lung compliance, improved oxygenation and a reduced work of breathing.²⁴ Effectiveness is increased when used in conjunction with appropriate positioning. The self-ventilating patient must be able to generate an adequate V_T as this volume is not augmented with CPAP (see Table 5.7).

NON-INVASIVE VENTILATION

In recent years there has been an expansion in the role of NIV in the ICU. This includes the prevention of invasive ventilation in patients with chronic obstructive pulmonary disease,²⁵ pulmonary oedema and immunocompromise; early weaning from mechanical ventilation; and potentially the prevention of reintubation in those who suffer extubation failure. In addition, V_T may be augmented during physiotherapy treatment to remove secretions, or when mobilising the patient (see Table 5.7). Improved oxygenation may be achieved using NIV when the patient is positioning to optimise V/Q (see Table 5.8).

TREATMENT ADJUNCTS AND TECHNIQUES

Positive expiratory pressure mask and flutter devices are specialised mucociliary clearance devices used by some patients with chronic lung disease. These devices are rarely introduced in the ICU setting.

CRITICAL CARE REHABILITATION

The effects of deconditioning on the cardiovascular (Table 5.9), respiratory (Table 5.10) and neuromusculoskeletal system (Table 5.11) are well documented.²⁶^–²⁸ This phenomenon occurs as a result of restricted physical activity, and reduces the ability to perform work. The effects of deconditioning can occur with even relatively short periods of immobility, and are significantly influenced by age, premorbid condition, nature of the illness/injury and pharmacological factors. The consequences of deconditioning are significant in terms of patient outcome, length of hospital stay, duration of rehabilitation and subsequent ability to function independently in the community.²⁹ The psychological impact of deconditioning should not be underestimated. Inability to function at a ‘normal’ level of activity may result in depression and reduced self-efficacy.

Table 5.9 Deconditioning and the cardiovascular system ^26,^28,³⁰

Cardiovascular system

↓ Stroke volume – ventricular remodelling and reduced preload (see ↓ Plasma volume)

↑ Heart rate (resting and exercising): ↓ vagal tone, ↑ sympathetic catecholamine secretion and ↑ cardiac β-receptor activity

↓ Cardiac output and systemic oxygen delivery

↓ VO_2max: magnitude highly correlated to duration, static exercise effective in preventing some decrease. Related to changes centrally (cardiac output) and peripherally (oxygen delivery and utilisation)

↓ Plasma volume: secondary to fluid shift and altered renin–angiotensin–aldosterone activity. Contributes to ↓ orthostatic tolerance

Orthostatic intolerance develops more rapidly in the elderly or those with cardiovascular pathology. Often slow to resolve

Increased blood viscosity and vascular stasis: predisposition to thromboembolism

Altered cardiovascular reflexes: proposed attenuated baroreflex-mediated sympathoexcitation and enhanced cardiopulmonary receptor-mediated sympathoinhibition. Contributes to orthostatic intolerance

Altered arterial/venous vascular function

Table 5.10 Deconditioning and the respiratory system ³¹^–³³

Respiratory system

Adverse effects on:

Functional residual capacity

Compliance (lung and chest wall)

Resistance

Closing volume

Respiratory muscle function – impaired strength and endurance, reduced performance of ventilatory pump, ↑ days of mechanical ventilation, complex weaning issues

Concept of ventilator-induced diaphragmatic dysfunction proposed (atrophy, fibre remodelling, oxidative stress and structural injury). Time-dependent reduction in force-generating capacity, secondary to disuse and passive shortening

Respiratory muscle weakness may be limited by judicious choice of ventilation mode. Role of inspiratory muscle training unclear

Table 5.11 Deconditioning and the neuromusculoskeletal system ^26,³⁴^–³⁷

Neuromusculoskeletal system

Muscle atrophy – protein degradation (loss of contractile protein, increased non-contractile tissue, e.g. collagen) and cytokine activity. Reduction in strength, especially lower-limb antigravity muscles (i.e. those involved with transferring and ambulation). Inactivity amplifies the catabolic response of skeletal muscle to cortisol, therefore there is more marked atrophy following trauma or illness. Particularly significant in patient groups with low relative muscle mass, e.g. the elderly. Nutritional countermeasures should be considered and carefully titrated to meet demands best

↓ Muscle endurance (cf. Table 5.10) – reduced muscle blood flow/red cell volume/capillarisation/oxidative enzymes and biochemical changes. Generally longer to rehabilitate compared to reduction in muscle strength

Muscle shortening or changes in peri-/intra-articular connective tissue (including chest wall and thoracic spine) → contractures, ↓ joint range of motion, pain. Positioning and stretching maintain range and delay invasion of non-contractile protein

Decreased bone mineral density (particularly trabecular bone) – may be attenuated by standing or resistance exercise. Rate of recovery tends to lag behind that of muscle strength. Increased risk of fracture on remobilisation, especially in elderly

Microvascular and biochemical changes in peripheral nerves impair neuromuscular function. Adversely affects maximal voluntary contraction, and balance/proprioceptive activity

Critical illness neuropathy and myopathy frequently develop in patients hospitalised in an ICU for > 1 week. Risk factors include sepsis, SIRS and severe MOF. Associated with higher mortality rate, prolonged ventilation and rehabilitation, disability and reduced quality of life

ICU, intensive care unit; SIRS, systemic inflammatory response syndrome; MOF, multiorgan failure.

An increasing volume of research suggests that the deleterious consequences of immobility may be in part attenuated by selected rehabilitation interventions.^38,³⁹ The physiotherapist possessing expertise in rehabilitation and exercise physiology should direct the multiprofessional team in evaluating individual patients, devising a therapeutic strategy and referring to other specialties (e.g. speech and language therapy, occupational therapy) as required. Considerations must include:

• current physiological reserve

• extent of physiological impairment (associated with deconditioning and coexisting pathology, e.g. sepsis, multiorgan failure, neurological insult, inotrope dependence)

• nutritional status

• premorbid physiological reserve

• premorbid functional ability

• extent of patient participation

• external limitations (e.g. surgical instructions, traction, sedation, paralysing agents)

• risk assessment for moving and handling

• selection of appropriate/validated outcome measures

Traditionally, exercise rehabilitation has progressed linearly from activity in bed, then sitting, and finally to standing/walking. The model demonstrated in Figure 5.1 represents a three-stage functional rehabilitation programme. It is supported by evidence that suggests that a multimodal training regime is required to maintain/restore both physiological and psychological performance after a period of immobility and illness.³⁹ The use of interlinking circles is intended to reflect the non-linear pattern of exercise progression more commonly utilised in patients with critical illness, e.g. patients may be able to stand using a tilt-table before they are able to tolerate sitting out of bed. The central shaded area represents the core components that should be addressed at every stage in the patient’s recovery. The areas bordered by the broken lines represent the progression or regression from one stage to the next. During all stages, the patient’s cardiopulmonary response must be closely monitored, and exercise titrated accordingly. Modifications (e.g. temporarily increasing the FiO₂ and/or level of ventilatory assistance) during exercise and in the early postexercise period may be necessary. Such modifications are commonly required as increasing physical activity invariably coincides with weaning from ventilatory support – both significant challenges to the physiological reserve.

Figure 5.1 Schemata representing three-stage functional rehabilitation programme.⁴¹

The wealth of evidence regarding deconditioning should play a central role in planning treatment, both preventive and rehabilitative. For example, those muscle groups known to be most adversely affected by disuse should be the first to be targeted with a gradual, progressive regime. During the remobilisation period, the multiprofessional team must be particularly mindful of those elements with delayed recovery, e.g. orthostatic tolerance and bone mass (predisposition to falls and fractures) and muscle endurance (diminished exercise tolerance).

It has been suggested that, in order to improve long-term outcomes for survivors of ICU (e.g. late mortality, ongoing morbidity, neurocognitive defects, functional disability, quality of life, economic burden), critical illness and its management should be viewed on a continuum and not merely the time spent in a critical care facility.²⁹ Consequently, rehabilitation must also reflect this change in focus, continuing into the community, outpatient or follow-up clinic setting.⁴⁰

In recent years the concept of ‘prehabilitation’ has been introduced. Some have argued the case for exercise training prior to planned ICU admissions in order to ameliorate functional capacity. It is proposed that this would enable an individual to withstand better the stressor of inactivity and decrease the duration of dependency post critical care discharge.²⁶

PATIENT PROBLEMS AFTER ICU DISCHARGE

A prolonged stay in ICU can be debilitating mentally and physically and can affect recovery after discharge (Table 5.12). In order to optimise a fast and effective recovery, a patient’s care plan should be multidisciplinary in origin with ongoing appropriate rehabilitation following discharge from the ICU and indeed hospital.

Table 5.12 Psychological, cardiopulmonary and functional problems often encountered after discharge from the intensive care unit

Psychological	Cardiopulmonary	Functional
Depression	Compromised cardiopulmonary system	Back pain
Fear	Difficulty clearing retained secretions (trache tube, mini-trach in situ)	Shoulder pain
Anxiety		Muscle atrophy/decreased strength
Confusion	Decreased lung volumes	Inability to carry out activities of daily living independently
Disorientation	Oxygen dependence
Flashbacks		Limited mobility
Lack of motivation		Poor exercise tolerance
Functional dependence		Poor gait pattern

PHYSIOTHERAPY ROLE EXPANSION

The nature of the critical care environment offers diverse opportunities for role expansion. The lead physiotherapist for the service must possess specialist cardiopulmonary and rehabilitative skills, as well as an expert knowledge of exercise physiology in health and disease. Furthermore, as a member of a dynamic multiprofessional team, it may be appropriate to extend diagnostic or clinical skills beyond the remit of conventional physiotherapy, e.g. developing weaning strategies, advanced tracheostomy management, bronchoscopy, prescription, arterial blood gas sampling and managing NIV services.

As an educator, the clinician must ensure that all professionals who provide physiotherapy input are competent in their assessment, clinical reasoning and skill execution. A commitment to audit and research is essential in order to ensure evidence-based service provision, clinical governance and best possible patient outcome.

PHYSIOTHERAPY AND CRITICAL CARE OUTREACH TEAMS

The development of specialist physiotherapist posts within critical care outreach teams (CCOTs) constitutes a prime example of role expansion. Following the publication of Comprehensive Critical Care⁴² CCOT services were developed to meet the actual or potential needs of patients through critical care provision ‘without walls’:

• Avert critical care admission where possible

• Facilitate timely critical care admission when appropriate

• Empower all health care staff by disseminating ward-based critical care skills

• Optimise patient management and make best use of critical care resources via effective clinical decision-making

The introduction of CCOT has been associated with a varied approach to team configuration; however it has been suggested that those following a multiprofessional model are most likely to affect clinical and organisational improvements.⁴³ Consequently, many teams have elected to employ a designated specialist physiotherapist who can bring physiotherapeutic expertise to the service whilst also developing generic outreach practitioner skills (e.g. advanced tracheostomy management, cannulation, venopuncture, prescription via patient group directions, arterial blood gas sampling, drug administration, advanced life support, management of central/peripheral lines, 12-lead electrocardiogram interpretation, ordering/interpreting blood results and chest X-rays).