How effective are oral hygiene measures for preventing pneumonia in critically ill people on ventilators?


Ventilator‐associated pneumonia (VAP) is a lung infection. It develops in patients who are on artificial breathing machines (ventilators) in hospitals for more than 48 hours. Often, these patients are very ill – they may have had a heart attack or stroke, a serious accident, or major surgery. They may be unable to breathe on their own because they are unconscious or sedated while they receive treatment. Ventilators supply patients with oxygen through a tube placed in the mouth or nose, or through a hole in the front of the neck. If germs enter through the tube and get into the patient’s lungs, this can lead to VAP. VAP is a potentially very serious complication in patients who are already very ill. It can cause worsening health and increases patients’ risk of dying.

Keeping a patient’s mouth clean and free of disease could help to prevent VAP. Oral hygiene care includes mouthwash, antiseptics, using swabs to clean the mouth, toothbrushing and tools like suction devices, which suck away fluid from the mouth. These measures can be used on their own or combined.

What was the research?

A systematic review to find out if oral hygiene care does prevent VAP, and whether some types of oral hygiene care are better than others.

Who conducted the research?

The research was conducted by a team led by Tingting Zhao from the Hubei-MOST KLOS & KLOBM, School and Hospital of Stomatology, Wuhan University, Wuhan, China, on behalf of Cochrane Oral Health. Xinyu Wu, Qi Zhang, Chunjie Li, Helen V Worthington and Fang Hua were also on the team.

What evidence was included in the review?

Data were extracted from 40 randomised controlled trials. A total of 5,675 critically ill people, who were hospitalised in intensive care units, were included in the studies evaluated in the review. Most studies involved adults only, though one study focussed on children and another on newborn babies. The studies took place in a range of countries, including China (10 studies), Brazil (6 studies), the USA (6 studies) and Iran (5 studies).

What did the evidence say?

13 of the studies compared chlorhexidine, a type of antiseptic, against placebo (a dummy treatment) or usual care. The evidence suggests that chlorhexidine probably prevents VAP from developing in very ill patients, and probably has little or no effect on the risk of dying. The authors also found that using chlorhexidine may make little or no difference to how long a patient spends in intensive care. We do not know from these studies whether using chlorhexidine as an oral care measure affects the length of time patients spend on a ventilator, or if it leads to any adverse or unwanted effects.

8 studies looked at toothbrushing against no tooth brushing, with or without an antiseptic. Toothbrushing may prevent VAP from developing in very ill patients, and it may have little or no effect on the risk of dying or the length of time a patient spends on a ventilator. We do not know if toothbrushing affects patients’ length of stay in the intensive care unit, or if it leads to adverse effects.

How good was the evidence?

Available evidence is of moderate to low certainty. Studies reported imprecise or inconsistent results, were conducted in ways likely to introduce error into the results or reported too little information.

What are the implications for caring for people in intensive care units?

Effective oral hygiene care is important for ventilated patients in intensive care to reduce VAP. Compared with placebo/usual care, chlorhexidine mouthwash or gel, as part of oral hygiene care, probably reduces the incidence of developing ventilator‐associated pneumonia in critically ill patients from 26% to about 18%. However, there is no evidence of a benefit for mortality or duration of mechanical ventilation or stay in intensive care. Low‐certainty evidence suggests that oral hygiene care including both antiseptics and toothbrushing may be more effective than oral hygiene care with antiseptics alone for reducing VAP incidence and length of stay in intensive care, but there was no evidence for a reduction in mortality or duration of mechanical ventilation. There is insufficient evidence to determine whether any of the interventions evaluated in the studies are associated with adverse effects.

What should researchers look at in the future?

Although the included studies provided some evidence for the benefits of oral hygiene care for critically ill patients to prevent ventilator‐associated pneumonia, incomplete reporting of studies is a major limitation. More consistent use of the CONSORT statement for reporting of randomised controlled trials (CONSORT 2012) would increase the value of research.


Zhao  T, Wu  X, Zhang  Q, Li  C, Worthington  HV, Hua  F. Oral hygiene care for critically ill patients to prevent ventilator‐associated pneumonia. Cochrane Database of Systematic Reviews 2020, Issue 12. Art. No.: CD008367. DOI: 10.1002/14651858.CD008367.pub4. Accessed 05 January 2021.

This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Group Editorial Base.

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