Many families ask: "My mother or father has been bedbound for a long time and I often hear phlegm in the throat. If someone comes every day to do chest percussion, will pneumonia from lying in bed be avoided?" This way of thinking often treats chest percussion as the main means of preventing hypostatic pneumonia. The facts are different. Chest percussion is at most a short-term support for selected patients, and what really prevents pneumonia is another, more basic set of everyday care.
In summary, physiotherapy (including early mobilisation, positioning and airway clearance) is quite safe and can help a long-term bedbound older adult to clear phlegm in the short term. To prevent hypostatic pneumonia, however, the key is still the overall combination of early mobilisation, regular turning and oral care. Chest techniques are only a supporting measure for particular patients, and the related evidence is mostly of low certainty. Families should not expect chest percussion alone to "cure" pneumonia or lower the risk of death (Chen et al. 2022, very uncertain evidence).
Why long-term bed rest leads to a lot of phlegm and hypostatic pneumonia
To see why chest percussion is not the main measure, the root of the problem has to be understood first. When an older adult is bedbound for a long time and stays in the same position, the lower and back parts of the lungs are compressed and ventilation falls, so secretions collect in the low-lying areas and are hard to clear. Because activity is low, deep breaths and spontaneous coughs become less frequent, the cilia in the airway clear less efficiently, and phlegm naturally builds up more and more.
The more central problem is whether "the cough is strong enough". Hypostatic pneumonia is common not only because secretions collect. A bedbound older adult also often has a weaker cough, and easily breathes mouth secretions or tiny amounts of food into the airway. The question is therefore not simply "how much phlegm there is". It depends on whether there is enough activity, whether turning is frequent, whether the cough is strong enough, and whether the mouth is clean, and these are the factors that decide the risk of infection. To learn how to tell "having phlegm" from "being unable to cough phlegm up", and which patients benefit most, first read the article on weak cough and retained secretions.
Three roles of physiotherapy in managing phlegm
When a physiotherapist follows a long-term bedbound patient, the work is far more than "patting the back". It starts from three directions, each with a different evidence base:
Of the three measures, the ones with the most preventive value are the first two (early mobilisation and positioning), and not simple reliance on chest percussion. For patients whose cough is so weak that even collected phlegm cannot be coughed up, advanced cough assistance techniques need to be considered. This involves a different set of clinical decision criteria, explained below.
Research evidence on airway clearance, and its limits
Having seen what physiotherapy actually does, its limits must also be stated clearly, otherwise it is easy to mistake "clearing phlegm" for "treating disease". The medical evidence for these techniques points in a fairly consistent direction: short-term use is safe and may help particular patients, but on the key clinical outcomes of curing disease or lowering mortality, the current evidence does not support it.
- For selected patients with a weak cough, airway clearance is safe and may help to clear phlegm in the short term
- Early mobilisation is safe and has overall benefit (such as shorter hospital stays for pneumonia; Mundy et al. 2003)
- Airway clearance in bronchiectasis may improve phlegm clearance, some lung function and quality of life (Lee et al. 2015, low quality)
- Chest percussion can "cure" or "prevent" simple pneumonia: it has not been shown to lower mortality or raise the cure rate (Chen et al. 2022, very low)
- An advanced cough assist machine (MI-E) always works: the current evidence is not enough to support or oppose it (Morrow et al. 2013)
- Chest percussion alone can replace overall activity, turning and oral care
In other words, in caring for a long-term bedbound patient, the role of chest physiotherapy is to "give the right measure to a suitable patient and provide short-term help", and it is not a course of treatment that can lower the rate of pneumonia or the death rate by itself. Exaggerating its effect only leads families who have no clinical indication to spend energy on unnecessary back patting. To learn which patients really benefit, and whether everyone needs chest percussion, see the overview on who really needs chest physiotherapy.
When to consider cough assistance
Most decisions in respiratory physiotherapy depend on individual assessment, and there is generally no single value that says when intervention must start. There is, however, one clinical reference marker with a specific number that is worth noting.
When the peak cough flow (PCF) is below 270 L/min, that is the reference threshold for considering a move to cough assistance. The AARC guideline states that patients with neuromuscular weakness or impaired cough function should use cough assistance techniques, especially when PCF is below this value (Strickland et al. 2013). The same guideline also stresses that if a patient can cough up phlegm alone, routine airway clearance is not advised, and the patient only needs to be taught an effective cough technique. As for advanced cough assistance devices such as mechanical insufflation-exsufflation (MI-E), Cochrane states that the current evidence is not enough to support or oppose their use (Morrow et al. 2013).
The first step in managing a bedbound patient is therefore to tell whether the patient "can cough but has collected phlegm" or "has no strength to cough at all". For the first, the care focus is positioning, turning and teaching an effective cough. Only the second (a weak cough with low PCF) needs cough assistance techniques to be considered, and chest percussion should not be given to every patient regardless of the situation.
Basic care to prevent hypostatic pneumonia: activity, turning and oral hygiene
Once the supporting role of chest techniques is clear, the central question is how to handle prevention in daily care. The key lies in three basic measures that look simple but are more solid.
- Keep as active as possible: where it is safe, help the older adult out of bed, sitting up or walking with support. Early mobilisation benefits the overall condition (Mundy et al. 2003)
- Turn regularly: keep up regular turning (generally once every 2 hours) and a semi-sitting position, so that phlegm does not collect in the same side of the lungs
- Keep the mouth clean: research in care homes shows that professional oral care may help to reduce pneumonia-related mortality (Liu et al. 2018, low-quality evidence, and the effect comes from oral care and not from chest techniques)
- After feeding, keep the upper body raised and turn the head to one side, to reduce the chance of saliva or food going down the wrong way
- Do not treat chest percussion as the main way of preventing pneumonia. If the patient can cough alone, do not pat the back routinely every day
Oral care deserves special attention. After reviewing data from care home residents, Cochrane found that, compared with usual care, professional oral care may reduce pneumonia-related mortality (relative risk 0.41). The risk of bias in those studies was high and the quality of evidence low, and this positive signal comes from oral care itself and has nothing to do with any chest physiotherapy technique (Liu et al. 2018). This supports the point that the key to preventing hypostatic pneumonia lies in overall activity, changes of position and oral hygiene, and not in patting the back alone. The wider rehabilitation of long-term bedbound patients (such as maintaining muscle strength and joint range of movement and preventing contracture) is covered in another section of this website. See recovery after a long hospital stay for details.
How a home physiotherapist works with carers in the home
Many old tenement flats, public housing units and subdivided flats in Hong Kong are cramped, and a bedbound older adult often stays in the same position for a long time. Turning is not frequent enough, so secretions collect easily in the same lobe of the lungs. At a home assessment, the physiotherapist demonstrates in person how to turn regularly (generally once every 2 hours) and adjust the semi-sitting position, and guides the carer in using pillows to support the body for side-lying drainage, so that phlegm does not stay in the low parts of the lungs for long.
Another common problem arises during feeding. Many families let the older adult lie flat straight after feeding, which easily leads to choking and tiny amounts of aspiration. The physiotherapist advises keeping the upper body raised for a while after eating or being fed, with the head turned to one side. If the older adult has difficulty swallowing, the physiotherapist works with the swallowing assessment of a speech therapist to reduce the risk of saliva or food being breathed in. When the registered physiotherapists at Nova Health provide home rehabilitation, they first assess the older adult's cough strength and observe whether the person can cough up secretions alone. They then put together a "turning timetable, a semi-sitting position after meals and daily oral care" into an everyday routine that carers can follow easily at home, and do not simply teach a set of chest percussion movements. Only when the cough is too weak and more advanced intervention is needed does the therapist consider cough assistance techniques, based on clinical markers such as PCF, and identify cases that need referral.
Local oral care resources (for carers' reference)
- The Tooth Club (牙齒俱樂部) of the Oral Health Education Unit of the Department of Health: how to clean the mouth of an older adult who has difficulty swallowing or is bedbound (no toothpaste, wipe the mouth dry after brushing, keep the upper body raised): toothclub.gov.hk/chi/adu_01_02_01_07.html
- The Hospital Authority's 智友站 palliative care oral care guide: smartpatient.ha.org.hk
- The Department of Health's Outreach Dental Care Programme for the Elderly (長者牙科外展服務計劃), which gives regular oral checks and care to frail older adults in residential care homes: dental service hotline 2961 8827
Common misunderstandings
Misunderstanding 1: the more chest percussion, the better pneumonia is prevented
- For patients with simple pneumonia, there is currently no evidence that chest percussion lowers mortality or raises the cure rate (Chen et al. 2022, very uncertain evidence)
- If the patient can cough up phlegm alone, clinical guidelines do not advise routine airway clearance (Strickland et al. 2013)
- If the patient has no related need, frequent back patting has no benefit and only uses up the carer's energy for nothing
Misunderstanding 2: pneumonia prevention depends wholly on chest percussion, and other care does not matter
- The focus of pneumonia prevention is early mobilisation, regular turning and positioning, and mouth cleaning, with chest percussion as only one part
- The clinical data on reducing the risk of death from pneumonia actually come from oral care and not from chest physiotherapy techniques, and the quality of that evidence is low (Liu et al. 2018)
- Cough assistance techniques are considered only when the patient's cough is too weak, and not every bedbound patient needs them (Strickland et al. 2013)