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Volume 5 Supplement 6

Autumn Scientific Meeting of the Association of Cardiothoracic Anaesthetists

  • Meeting abstract
  • Open Access

Perioperative melatonin secretion in patients undergoing coronary artery bypass graft surgery: a pilot study

  • X Guo1,
  • E Kuzumi1 and
  • A Vuylsteke1
Critical Care20015(Suppl 6):2

Published: 4 January 2001


MelatoninMelatonin LevelSpecific Time PointPostoperative DeliriumBiological Clock


Melatonin, a neurohormone, plays important roles in adjusting the 'biological clock', and is an important mediator in many normal physiological functions [1]. Melatonin disturbances have been linked to neuropsychological dysfunction and postoperative delirium [2]. However, there have been no reports on postoperative melatonin levels to date. The aim of the present study was to observe perioperative melatonin secretion in patients undergoing coronary artery bypass graft surgery.

Patients and methods

After local ethics committee approval and informed consent, 11 male patients aged between 60 and 78 years, who were scheduled for elective coronary artery bypass graft surgery under hypothermic cardiopulmonary bypass, were enrolled in the study. All patients received the same anaesthesia regimen, which is used routinely at Papworth Hospital. Blood samples for measurements of melatonin were taken during the day of surgery at specific time points and every 3 h on postoperative days 2 and 3. Plasma concentrations of melatonin were measured using a radioimmunoassay method.


During surgery melatonin levels were below the minimum sensitivity level in most patients, but low levels, without circadian variation, were measured during the first postoperative night in some patients (n = 7; Fig. 1). Circadian secretion was observed on the third postoperative night, irrespective of whether the patient was on the ward (n = 6) or in the intensive care unit (ICU; n = 3; Fig. 1). However, the peak level of melatonin was observed 3 h later in patients who remained in the ICU (Fig. 1).
Figure 1

Figure 1


Melatonin secretion is impaired during cardiac surgery and in the immediate postoperative period. However, a circadian rhythm is present from postoperative day 2. The clinical implication of this observation has to be evaluated further.



X Guo is sponsored by the Royal Society Fellowship.

Authors’ Affiliations

Department of Anaesthesia, Papworth Hospital, Cambridge, UK


  1. Webb SM, Puig-Domingo M: Role of melatonin in health and disease. Clin Endocrinol. 1995, 42: 221-234.View ArticleGoogle Scholar
  2. Uchida K, Aoki B, Ishizuka B: Postoperative delirium and plasma melatonin. Med Hypo. 1999, 53: 103-106. 10.1054/mehy.1998.0724.View ArticleGoogle Scholar


© BioMed Central Ltd on behalf of the copyright holder 2000