Association of Plasma Melatonin Levels With Delirium

• The diagnose of postoperative delirium [ Time Frame: One trained physician performed assessments of delirium at 1 hour after operation, and 8 AM and 5 PM of postoperative day 1 and 2. ] [ Designated as safety issue: Yes ]
  One trained physician performed assessments of delirium using Confusion Assessment Method for the intensive care unit at 1 hour after operation, and 8 AM and 5 PM of postoperative day 1 and 2.
  
  

• The measurements of plasma melatonin levels [ Time Frame: We collected blood samples for the measurement of plasma melatonin levels at 1) 8 AM before operation, 2) 1 hour after operation, 3) 8 AM of postoperative day 1 and 4) 8 AM of postoperative day 2. ] [ Designated as safety issue: Yes ]
  We collected blood samples for the measurement of plasma melatonin levels at 1) 8 AM before operation, 2) 1 hour after operation, 3) 8 AM of postoperative day 1 and 4) 8 AM of postoperative day 2.Plasma was separated by centrifugation and the plasma was stored at least -30 degrees Celsius in a polypropylene tube until the time of assay. Plasma melatonin levels were measured with a melatonin radioimmunoassay kit (Buhlmann Laboratories AG, Allschwil, Switzerland).
  
  

Delirium is common complications in postoperative critically ill patients. Although the mechanism of postoperative delirium is not well understood, there are several studies to report alternation of plasma melatonin levels after general anesthesia and suggest the link between delirium and abnormal tryptophan-serotonin-melatonin metabolism. However, there are few studies to assess the association of perioperative plasma melatonin levels with postoperative delirium and/or general anesthetics.

The investigators designed a prospective observational study to investigate the association of perioperative plasma melatonin levels with postoperative delirium and general anesthesia. The investigators included 33 patients required intensive care more than 48 hours after sevoflurane anesthesia in an academic tertiary care hospital. The investigators measured plasma melatonin levels and assessed postoperative delirium using Confusion Assessment Method for the intensive care unit (CAM-ICU). The investigators compared perioperative plasma melatonin levels between patients with and without delirium, and assessed associations of patients' demographics and anesthesia with plasma melatonin levels.