Chapter 7: Moving and positioning
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Positioning a patient to minimize the work of breathing
Anatomy and physiology
At rest, inspiration is an active process whereas expiration is passive. The main muscle involved in inspiration is the diaphragm (Figure 7.14). The diaphragm contracts, thereby increasing the volume of the thoracic cavity. Additionally, the external intercostal muscles work by pulling the sternum and ribcage upwards and outwards, in a process likened to a pump and bucket handle (Figure 7.15). When increased ventilation is required (e.g. with exercise or in disease), the accessory muscles (the scalenes and sternocleidomastoid) assist with this process (Tortora and Derrickson [122]).
Figure 7.14 The diaphragm as seen from the front. Note the openings in the vertebral portion for the inferior vena cava, oesophagus and aorta.
Figure 7.15 Movement of the chest wall on inspiration. (a) The upper ribs move upwards and forwards, increasing the anteroposterior dimension of the thoracic cavity. As a result, the sternum also rises forwards. (b) The lower ribs move like bucket handles, increasing the lateral dimension of the thorax. Source: Aggarwal and Hunter ([6]). Reproduced with permission of BMJ Publishing Group Ltd.
If ventilation is increased for a prolonged period of time, as in respiratory disease, the diaphragm's activity reduces and the accessory muscles take on a higher proportion of the work. This can be observed in a patient who adopts a posture with raised shoulders.
Although expiration should be passive in normal conditions, the internal intercostals and muscles of the abdominal wall (the transversus abdominis, the rectus abdominis, and the internal and external obliques) are used in times of active expiration to push the diaphragm upwards, reducing the volume of the thoracic cavity and forcefully expelling air. This can be observed clinically when the abdominal wall visibly contracts and pulls in the lower part of the ribcage during expiration (Tortora and Derrickson [122]).
Evidence‐based approaches
Principles of care
Many people suffering with long‐term breathlessness adopt positions that will best facilitate their inspiratory muscles (Bott et al. [13]). The aim of any position is to restore a normal rate and depth of breathing in order to achieve efficient but adequate ventilation (Box 7.2).
Box 7.2
Positioning to minimize the work of breathing
There are certain resting positions that can help to reduce the work of breathing, as shown in Figure 7.16.
These positions serve to:
- support the body, reducing the overall use of postural muscles and oxygen requirements
- improve lung volumes
- optimize the functional positions of the respiratory (thoracic and abdominal) muscles (De Troyer and Boriek [27]).
Figure 7.16 Positions to reduce the work of breathing.
Pre‐procedural considerations
The general procedural considerations mentioned earlier in this chapter are all relevant to this section. However, there are also some other general principles that need to be considered for these patients.
Pharmacological support
Administering nebulizers
If prescribed, administering nebulizers approximately 15 minutes prior to moving a patient will help to dilate the airways, making breathing more efficient and ensuring better oxygen delivery to the blood (Boe et al. [11]).
Oxygen requirements
Repositioning can cause a temporary fall in oxygen saturation or a raised respiratory rate. If the fall is greater than 4% or recovery time is protracted, supplemental oxygen delivery may be required for several minutes before, during and after moving. Consideration should be given to patients who have chronic obstructive pulmonary disease or who are chronic carbon dioxide retainers as supplementary oxygen will cause a negative impact on their respiratory function by reducing their respiratory drive (Kent et al. [57]).
Non‐pharmacological support
Pacing
It may be necessary to allow the patient time to rest during the process of getting into a new position to limit the exertion and therefore decrease the respiratory demand.
Environment
A breathless patient may be anxious about carrying out a task that could exacerbate their breathlessness. By reducing additional stressors such as noise and a cluttered environment, this can be minimized.
