Acute respiratory distress syndrome secondary to cardiopulmonary bypass: do compromised plasma iron-binding anti-oxidant protection and thiol levels influence outcome?
OBJECTIVE
Cardiopulmonary bypass (CPB) surgery is often associated with mild lung injury and in some patients leads to acute lung injury and acute respiratory distress syndrome (ARDS). Aberrant plasma iron chemistry (increased iron loading of transferrin and/or the presence of redox-active low molecular mass iron) and increased plasma thiol levels are features of this type of surgery and represent a potential pro-oxidant risk for oxidative damage. Oxidative damage is a feature of ARDS, and we hypothesized that pro-oxidant forces may contribute to the onset and progression of ARDS.


METHODS
Prospective, single center, observational study.


METHODS
University-affiliated tertiary referral cardiothoracic center.


METHODS
A total of 19 patients with ARDS secondary to CPB surgery and 64 patients with ARDS secondary to a variety of other predisposing causes.


METHODS
Supportive techniques appropriate to the treatment of ARDS.


RESULTS
Blood samples were collected into lithium heparin tubes for all patient groups on the first day of the admission of patients to the intensive care unit immediately after the diagnosis of ARDS. Plasma was immediately assayed for thiol content and total protein and albumin levels. Plasma from patients with ARDS secondary to CPB surgery was also assayed for changes in iron chemistry. Nonsurviving patients with ARDS secondary to CPB surgery displayed significantly greater levels of aberrant iron chemistry (elevated levels of iron saturation of transferrin) with decreased iron-binding antioxidant protection and elevated plasma thiol levels than did survivors. Plasma thiol levels in patients with ARDS secondary to other predisposing causes were (with the exception of lung-surgery patients) significantly elevated in survivors compared with those in nonsurvivors of the syndrome.


CONCLUSIONS
Increased levels of plasma thiol appear to be associated with mortality in patients with ARDS secondary to CPB surgery.
Oxygen Chemistry Laboratory, Royal Brompton Hospital, and Imperial College of Science, Technology and Medicine, London, UK.
G J
GJ
Quinlan
S
S
Mumby
N J
NJ
Lamb
L K
LK
Moran
T W
TW
Evans
J M
JM
Gutteridge
D018806:APACHE; D000328:Adult; D000368:Aged; D001798:Blood Proteins; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D001026:Coronary Artery Bypass; D006801:Humans; D007362:Intensive Care Units; D007501:Iron / Q000097:blood / Q000378:metabolism*; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000097:blood* / Q000209:etiology* / Q000401:mortality; D012709:Serum Albumin; D013438:Sulfhydryl Compounds / Q000097:blood*; D014168:Transferrin / Q000378:metabolism*
D001798:Blood Proteins; D012709:Serum Albumin; D013438:Sulfhydryl Compounds; D014168:Transferrin; D007501:Iron