The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [231]
Respiratory function
Due to the immobility of the unconscious patient, there is an increased threat of developing respiratory complications such as atelectasis, pneumonia, aspiration and airway obstruction. Respiratory assessment should be carried out prior to moving and changing position in order to provide a baseline that can be referred to following the procedure. The assessment should include checking patency of the airway, monitoring the rate, pattern and work of breathing, pulse oximetry* to check oxygen saturations* and blood gases to assess adequacy of gaseous exchange.
Patients may require mechanical ventilation for the following reasons.
Inability to ventilate adequately, for example post anaesthesia or inspiratory muscle fatigue or weakness.
Inability to protect own airway or presenting with upper airway obstruction.
Ability to breathe adequately but inadvisable, for example with an acute head injury.
Mechanical ventilation may be required for days, weeks or even months (MacIntyre and Branson 2009). It is worth remembering that mechanically ventilated patients often cannot express any sort of preference for certain body positions. If the patient is intubated with an endotracheal tube they are at increased risk of developing nosocomial infections (Hickey 2003a) so it is important that lung volumes and respiratory mechanics should be continuously monitored (Hickey 2003a). For more information see Moving and positioning the patient with respiratory compromise.
Moving and positioning the patient with respiratory compromise
Definition
The causes of respiratory compromise may be multifactoral and should be established before undertaking positioning interventions. Compromise may be due to medical intervention (e.g. side-effects of medication), metabolic, surgical or primary respiratory pathologies. The guidelines regarding principles of moving and positioning are applicable to these patients but particular observation is required regarding their response to the intervention.
Anatomy and physiology
Both skeletal and muscular structures that make up the thoracic cage and surround the lungs play a vital role in respiration (see Chapter 10 for more details). Compromise of one or more of these (e.g. abdominal muscle dysfunction due to abdominal surgery, ascites or deconditioning) may lead to an alteration in normal respiratory function and the ability to generate an effective cough (Hodges and Gandevia 2000).
Evidence-based approaches
Principles of care
The main aim of positioning management of the patient with respiratory symptoms is to:
maximize ventilation/perfusion (V/Q) matching
minimize the work of breathing (WOB)
maximize the drainage of secretions.
In many instances positioning, as outlined above, may enhance medical management by the use of the effects of gravity upon the cardiovascular and respiratory systems. This may reduce the need for more invasive intervention (Jones and Moffatt 2002) such as mechanical ventilation. Therefore, the most advantageous positioning should be integrated into the overall 24-hour plan, and positions that may have an adverse effect should be avoided (ACPRC 1996).
The general principles of care mentioned earlier in the chapter are all relevant to this section.
Positioning to maximize ventilation/perfusion matching
Definition
For optimal gaseous exchange to take place, it is necessary that the air and the blood are in the same area of lung at the same time. Matching of these is expressed as a ratio of alveolar ventilation to perfusion (V/Q). A degree of mismatch can occur either due to adequate ventilation to an underperfused area (dead space) or inadequate ventilation to a well-perfused area (shunt).
Anatomy and physiology
The function of the lungs is to exchange oxygen and carbon dioxide between the blood and atmosphere. Oxygen from the atmosphere comes into close contact with blood via the alveolar capillary membrane. Here it diffuses across into the blood and is carried around the body. The amount of oxygen that reaches the blood depends on the rate