Clinical Trial Network

COMMAS: “A 0.2% Chlorhexidine mouthwash prior to anaesthesia in patients undergoing major elective abdominal surgery to reduce pneumonia: An international, pragmatic, multicentre, observer blinded, randomised controlled study”

Chief Investigator: Dr. Ravinder VOHRA (Nottingham University Hospitals, Nottingham, United kingdom)

Download the study flyer!  

Medical Problem

The impact of pneumonia following surgery: Pneumonia affects 14% of patients following open elective abdominal surgery every year for diseases of the bowel, liver, and pancreas.  Epidemiological studies show pneumonia is associated with an increase in 30-day perioperative mortality, from 2.5% in those with no pneumonia, to 18%. In addition, pneumonia adds 7 extra days in hospital. One of the primary routes of bacterial entry into the lower respiratory tract is aspiration of oral and pharyngeal pathogens at the time of intubation.

Chlorhexidine mouthwash: Across Europe, 0.2% chlorhexidine mouthwash is a widely available, antiseptic agent. It is commonly used to control dental plaque and given routinely before and after oral surgery to reduce local and systemic infective complications. Experimental data shows that a single administration of 0.2% chlorhexidine mouthwash reduces the total oral microbial numbers by >80% within one minute. In particular, a single chlorhexidine mouthwash can reduce the microbial contamination of instruments that traverse the oral cavity.

One hypothesis is that 0.2% chlorhexidine administered as a mouthwash immediate prior to anaesthesia may reduce the incidence of pneumonia within 30 days by reducing the oral bacterial load. Chlorhexidine mouthwash is a potentially inexpensive intervention that could reduce perioperative mortality.


Primary: To determine whether 0.2% chlorhexidine mouthwash, administered prior to anaesthesia, compared to standard care, reduces pneumonia within 30 days of major elective abdominal surgery

Secondary: To determine whether 0.2% chlorhexidine mouthwash use reduces nosocomial infections, length of hospital stay and improves quality of life.

 Inclusion Criteria

Inpatients aged ≥45 years undergoing elective elevated-risk, noncardiac, nonthoracic surgery based on combined clinical and surgical assessment (Revised Cardiac Risk Index, NSQIP score), i.e. who should be asked about METs according to current guidelines.

Exclusion Criteria

Low-risk surgery; patients unable to ambulate due to congenital or neurological disease (e.g. paraplegics; in contrast, patients for orthopaedic surgery, e.g. hip replacement, will be included); unwillingness to participate.


  • Study selected by ESA Research Committee: March 2016
  • Call for centres: Ongoing 
  • Recruitment of patients: Planned for end of 2017

Join the study

This study will recruit as many participating institutions as possible. Would your hospital like to join this study as an actively contributing research centre? The ‘Call for Centres form’ must be filled in online. The completion of this form will facilitate the coordination and is mandatory for participation in ESA CTN. ESA Secretariat will then contact you providing you with additional information.Please visit the call for centres page 

Steering Committee

Dr. Ravinder Vohra , Prof. Rupert Pearse, Dr. Olga Tucker and the West Midlands Research Collaborative  


The Study is entirely sponsored by a grant from the European Society of Anaesthesiology Clinical Trial Network (ESA CTN). The aim of the European Society of Anaesthesiology Clinical Trial Network is to provide an infrastructure for clinical research in the fields of Anaesthesia, Pain, Intensive Care and Emergency Medicine by transnational European collaborative studies.


Contact us

European Society of Anaesthesiology - Research Department

Rue des Comédiens 24
1000 Brussels, Belgium
T: +32 2 743 32 94 / +32 2 210 94 14
F: +32 2 743 32 98