الفهرس 
Interleukin-6Only 14 pages are availabe for public view
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Abstract
In response to infections, inflammatory agents or surgical trauma
the immune system is activated by a series of small proteins named
‘interleukins’ as it was originally believed that those compounds were
exclusively produced by and for leucocytes. Nowdays, the term
‘cytokine’ is preferred to signify that the sources and actions include a
wide variety of cell type (Deuren et al., 1992).
For many years, researchers and clinicans have been concerned
about the potential impact of anaesthetic agents on human immune
system functions. This interest stems from a variety of theoretical and
clinical observations centering around both the high rate of infections
seen in postoperative patients (Cruse and Foord, 1973), and the
demonstrated bons marrow depression after prolonged anaesthetic
exposure (Brodsky, 1985).
The contributory role of anaesthetic agents to the immune
impairment is poorly understood, however, it would appear that many of
the immune changes seen in surgical patients are primarily the result of
the surgical trauma (cautery, tissue damage and organ manipulation) and
endocrine responses (increased ACTH, catecholamines and
corticosteroids), rather than the result of anaesthetic exposure itself
(Watkins, 1982 and Moudgil, 1986).
Surgery and associated infections stimulate production of a variety
of endogenous mediators and these mediators initiate alterations in
various organs that are integral to the response of the host to injury (Fong
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et al., 1995). Among these, stress response, activation of
hypothalmopituitary-adrenal (HPA) axis and resultant stimulation of
glucocorticoid secretion seem to be of extreme importance (Fraser et al.,
1952 and Weissman, 1990). Interaction between the immune and
neuroendocrine system has been investigated (Immura et al., 1991). In
this interaction, cyotokines (especially IL-6)-play an important role as the
afferent signal to the neuroendocrine system. Several cytokines,
especially interleukin-6 (Naitoh et al., 1988) activate the HPA axis,
acting at the central nervous system and other levels (Fraser et al., 1952).
The aim of this study was to throw a light on the effect of general
versus both epidural and spinal anesthesia on cytokine production
especially IL-6 (because it’s the main and major cytokine released after
routine surgery). This study was conducted on 60 patients (ASA class I,
II) scheduled for major elective surgery. They were diveded into 3 main
groups, each consisting of 20 patients. The first group (Group I) consisted
of 20 patients subjected to general anesthesia, while the second group
(Group II) consisted of 20 patients who received epidural anesthesia
while the 3 groups (Group III) was consisted of 20 patients who received
spinal anesthesia.
All patients were premedicated with benzodiazepines (diazepam
5mg orally on the night before surgery and midazolam 10mg i.m., 30
minutes preoperatively).
General anesthesia was induced with fentanly (1-2mg/kg/B.W.),
sodium thiopentone (sleeping dose) and suxamethonium (1mg.kg-1) to
facilitate endotracheal intubation. Pancuronium bromide (0.08mg.kg.B.W.)
was administered for skeletal muscle relaxation and the lungs were
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mechanically ventilated with 60% N2O in oxygen and halothane 0.5-
1.0%.
For epidural anaesthesia, the selected patients were preloaded with
500 ml Ringer’s solution. The epidural space was approached at the level
of L2/ L3 or L3/L4 interspace using the standard loss of resistance
technique with saline and an epidrual catheter was inserted. The epidural
blockadge was performed with bupivacaine hydrochloride (0.5%) 15cc
(5mg.ml-1), and lidocaine hydrochloride (1%) 5cc. Additional top-up
doses of lidocaine (0.5%) 2.5cc and bupivacaine (0.25%) 7.5cc were
administered according to the patients’ needs and to maintain analgesia
during surgery.
For spinal anaesthesia each patient was received 500ml of ringer’s
solution as a pre- load and after positioning of the patient (sitting) and
identification of the space (L4, L5) the spinal needle (G. 20), was then
introduced, and a successful dural puncture was confirmed by
withdrawing the stylet to verify free CSF flow, and then after connection
of syringe the local anaesthetic was injected (bubivacacaine
hydrochloride (0.5%) 5mgl/ml (4CC) and the needle was then withdrawn,
sterile dressing was placed over the site of injection and the patient was
placed supine and analgesia was then confirmed by the pin-prick testing
before skin incision.
Blood samples were obtained before surgery, before skin incision,
immediately postoperatively, 2 hours later and at 24 hours after surgery
for the estimation of serum cytokines (IL- 6), together with plasma
cortisol and ACTH levels.
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In conclusion:
IL-6 was the main and major cytokine released after routine
surgery. Serum IL-6 levels showed no significant increase pre-operative
or before skin incision while it was significantly increased
postoperatively after all types of anesthesia with no significant difference
between all types of anesthesia pointing to the close relation of such
cytokine (IL-6) to the surgical procedure and the severity of the surgical
trauma (tissue damage and manipulation) rather than the anesthetic
technique used.
As regard plasma cortisol and ACTH levels they were more
significantly elevated after general anesthesia than after both epidural and
spinal anesthesia, this could explain bi-directional communication that
exists between the immune and the endocrine system.