HyPerMICROBE is a single-centre, controlled, randomised, prospective, superiority clinical trial to compare the efficacy of daily oral care with 3% hydrogen peroxide (Oroxid®) versus standard of care (0.2% chlorhexidine digluconate) on the cumulative incidence of lower respiratory tract microbial colonisation in mechanically ventilated adult critically ill patients.

Rationale: Ventilator-associated pneumonia (VAP) is the most common hospital-acquired infection (HAI) in the intensive care unit (ICU), and its impact is very high in terms of morbidity, length of hospital stay and overall costs. Chlorhexidine for oral care in critically ill has no clear impact on VAP rates and may cause harm. 3% hydrogen peroxide (Oroxid) could be a promising substitute.

Aim: To test effectivity and safety of 3% hydrogen peroxide solution on ventilator-associated complications

Design: Prospective, single center, parallel group randomised controlled trial. Subjects: ICU patients (general ICU)

Treatment in the intervention group: daily oral care with 3% hydrogen peroxide

Control group: Standard-of-care protocolised daily oral care with 0,2% chlorhexidine

Primary outcome: Cumulative incidence of lower respiratory tract microbial colonisation analysed by Kaplan-Maier method, censored in the case of ICU discharge or extubation > 24h.

Secondary and exploratory outcomes: Differences in the relative risk of infection related ventilator-associated complications, antibiotic (ATB) consumption analysis, intraoral complications, reported using the Bedside oral exam (BOE) score, validated and adopted for ICU, length of ICU stay in days (time frame: at 3 months), number of ventilator-free days (time frame: at 28 days); that is, number of days, out of 28 days after admission, that patient has not been supported by mechanical ventilation

Inclusion Criteria:

1. Age ≥18 years
2. In-patient of ICU and expected to stay > 5 days
3. Mechanical ventilation or imminent need of it; predicted length of mechanical ventilation (MV) ≥ 72h
4. Clinical Pulmonary Infection score (CPIS) less than 6 at the baseline
5. No history and symptoms of aspiration at the baseline

Exclusion Criteria:

1. ATB therapy of respiratory infection on admission
2. Suspected pulmonary infection on admission and in the first 48h of mechanical ventilation
3. Pregnancy
4. Oral ulcers or injuries
5. Patient with a history of hydrogen peroxide allergy

Due to the nature of the intervention nurses can't be blinded to allocation (the mouthwash type - nature of the fluid, its odour etc.), but are strongly inculcated not to disclose the allocation status of the participant at the follow up assessments. As the ICU is paperless and fully computerised, the data in the computer can be acquired and analysed by the researchers without having access to information about the allocation.