Background Ventilator-associated pneumonia (VAP) is defined as pneumonia developing in people who have received mechanical ventilation for at least 48 hours. VAP is a potentially serious complication in these patients who are already critically ill. Oral hygiene care (OHC), using either a mouthrinse, gel, swab, toothbrush, or combination, together with suction of secretions, may reduce the risk of VAP in these patients. Objectives To assess the effects of oral hygiene care (OHC) on incidence of ventilator-associated pneumonia in critically ill patients receiving mechanical ventilation in hospital intensive care units (ICUs). Search methods Cochrane Oral Healths Information Specialist searched the following databases: Cochrane Oral Healths Trials Register (to 25 February 2020), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2020, Issue 1), MEDLINE Ovid (1946 to 25 February 2020), Embase Ovid (1980 to 25 February 2020), LILACS BIREME Virtual Health Library (1982 to 25 February 2020) and CINAHL EBSCO (1937 to 25 February 2020). We also searched the VIP Database (January 2012 to 8 March 2020). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. Selection criteria We included randomised controlled trials (RCTs) evaluating the effects of OHC (mouthrinse, gel, swab, toothbrush or combination) in critically ill patients receiving mechanical ventilation for at least 48 hours. Data collection and analysis At least two review authors independently assessed search results, extracted data and assessed risk of bias in included studies. We contacted study authors for additional information. We reported risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes, using the random-effects model of meta-analysis when data from four or more trials were combined. Main results We included 40 RCTs (5675 participants), which were conducted in various countries including China, USA, Brazil and Iran. We categorised these RCTs into five main comparisons: chlorhexidine (CHX) mouthrinse or gel versus placebo/usual care; CHX mouthrinse versus other oral care agents; toothbrushing (+/- antiseptics) versus no toothbrushing (+/- antiseptics); powered versus manual toothbrushing; and comparisons of other oral care agents used in OHC (other oral care agents versus placebo/usual care, or head-to-head comparisons between other oral care agents). We assessed the overall risk of bias as high in 31 trials and low in two, with the rest being unclear. Moderate-certainty evidence from 13 RCTs (1206 participants, 92% adults) shows that CHX mouthrinse or gel, as part of OHC, probably reduces the incidence of VAP compared to placebo or usual care from 26% to about 18% (RR 0.67, 95% confidence intervals (CI) 0.47 to 0.97; P = 0.03; I-2 = 66%). This is equivalent to a number needed to treat for an additional beneficial outcome (NNTB) of 12 (95% CI 7 to 128), i.e. providing OHC including CHX for 12 ventilated patients in intensive care would prevent one patient developing VAP. There was no evidence of a difference between interventions for the outcomes of mortality (RR 1.03, 95% CI 0.80 to 1.33; P = 0.86, I-2 = 0%; 9 RCTs, 944 participants; moderate-certainty evidence), duration of mechanical ventilation (MD -1.10 days, 95% CI -3.20 to 1.00 days; P = 0.30, I-2 = 74%; 4 RCTs, 594 participants; very low-certainty evidence) or duration of intensive care unit (ICU) stay (MD -0.89 days, 95% CI -3.59 to 1.82 days; P = 0.52, I-2 = 69%; 5 RCTs, 627 participants; low-certainty evidence). Most studies did not mention adverse effects. One study reported adverse effects, which were mild, with similar frequency in CHX and control groups and one study reported there were no adverse effects. Toothbrushing (+/- antiseptics) may reduce the incidence of VAP (RR 0.61, 95% CI 0.41 to 0.91; P = 0.01, I-2 = 40%; 5 RCTs, 910 participants; low-certainty evidence) compared to OHC without toothbrushing (+/- antiseptics). There is also some evidence that toothbrushing may reduce the duration of ICU stay (MD -1.89 days, 95% CI -3.52 to -0.27 days; P = 0.02, I-2 = 0%; 3 RCTs, 749 participants), but this is very low certainty. Low-certainty evidence did not show a reduction in mortality (RR 0.84, 95% CI 0.67 to 1.05; P = 0.12, I-2 = 0%; 5 RCTs, 910 participants) or duration of mechanical ventilation (MD -0.43, 95% CI -1.17 to 0.30; P = 0.25, I-2 = 46%; 4 RCTs, 810 participants). Authors' conclusions Chlorhexidine mouthwash or gel, as part of OHC, probably reduces the incidence of developing ventilator-associated pneumonia (VAP) in critically ill patients from 26% to about 18%, when compared to placebo or usual care. We did not find a difference in mortality, duration of mechanical ventilation or duration of stay in the intensive care unit, although the evidence was low certainty. OHC including both antiseptics and toothbrushing may be more effective than OHC with antiseptics alone to reduce the incidence of VAP and the length of ICU stay, but, again, the evidence is low certainty. There is insufficient evidence to determine whether any of the interventions evaluated in the studies are associated with adverse effects.
