title: Plasma glutamine levels before cardiac surgery are related to post-surgery infections; an observational study.
abstract: BACKGROUND
  A low plasma glutamine level was found in 34% of patients after elective cardiothoracic surgery. This could be a result of the inflammation caused by surgical stress or the use of extracorporeal circulation (ECC). But it is also possible that plasma glutamine levels were already lowered before surgery and reflect an impaired metabolic state and a higher likelihood to develop complications. In the present study plasma glutamine levels were measured before and after cardiac surgery and we questioned whether there is a relation between plasma glutamine levels and duration of ECC and the occurrence of postoperative infections.
  
  
  METHODS
  We performed a single-centre prospective, observational study in a closed-format, 20-bed, mixed ICU in a tertiary teaching hospital. We included consecutive patients after elective cardiac surgery with use of extracorporeal circulation. Blood samples were collected on the day prior to surgery and at admission on the ICU. The study was approved by the local Medical Ethics Committee (Regional Review Committee Patient-related Research, Medical Centre Leeuwarden, nWMO 115, April 28th 2015).
  
  
  RESULTS
  Ninety patients were included. Pre-operative plasma glutamine level was 0.42 ± 0.10 mmol/l and post-operative 0.38 ± 0.09 mmol/l (p < 0.001). There was no relation between duration of extracorporeal circulation or aortic occlusion time and changes in plasma glutamine levels. A logistic regression analysis showed a significant correlation between the presence of a positive culture during the post-operative course and pre-operative plasma glutamine levels (p = 0.04).
  
  
  CONCLUSIONS
  Plasma glutamine levels are significantly lower just after cardiac surgery compared to pre-operative levels. We did not find a relation between the decrease in plasma glutamine levels and the duration of extracorporeal circulation or aortic clamp time. There was a correlation between pre-operative plasma glutamine levels and the presence of a positive culture after cardiac surgery.
  
  
  BACKGROUND
  ClinicalTrials.gov, number NCT02444780 .
authors.affiliation: Departments of Intensive Care, Medical Centre Leeuwarden, Henri Dunantweg 2, 8935 AD, Leeuwarden, The Netherlands. Hanneke.Buter@znb.nl.
authors.forename: Hanneke
authors.identifier: http://orcid.org/0000-0001-8594-9079
authors.initials: H
authors.lastname: Buter
authors.affiliation: Departments of Intensive Care, Medical Centre Leeuwarden, Henri Dunantweg 2, 8935 AD, Leeuwarden, The Netherlands.
authors.forename: Matty
authors.initials: M
authors.lastname: Koopmans
authors.affiliation: Clinical Chemistry, Medical Centre Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Ramses
authors.initials: R
authors.lastname: Kemperman
authors.affiliation: Cardiovascular Surgery, Medical Centre Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Lilian
authors.initials: L
authors.lastname: Jekel
authors.affiliation: Departments of Intensive Care, Medical Centre Leeuwarden, Henri Dunantweg 2, 8935 AD, Leeuwarden, The Netherlands.
authors.forename: Christiaan
authors.initials: C
authors.lastname: Boerma
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D017558:Elective Surgical Procedures / Q000009:adverse effects; D005112:Extracorporeal Circulation / Q000009:adverse effects; D005260:Female; D005973:Glutamine / Q000097:blood*; D006331:Heart Diseases / Q000097:blood* / Q000601:surgery*; D006801:Humans; D007239:Infections / Q000209:etiology* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies
chemical_list: D005973:Glutamine
keywords: Cardiac surgery; Plasma glutamine level; Postoperative infection