THE NEUROENDOCRINE RESPONSE TO GYNAECOLOGICAL SURGERY: COMPARING THE MODULATING EFFECT OF TWO ANAESTHETIC TECHNIQUES

Abstract

Forty-four healthy patients with the American Society of Anesthesiologists (ASA)
physical status I and II scheduled for elective myomectomy and total abdominal
hysterectomy were studied. They were randomly allotted by blind balloting to one of two
groups of twenty-two; group I patients received balanced general anaesthesia relaxant
technique (GAR), and group II patients received combined spinal epidural anaesthesia
(CSEA).
Four blood samples were obtained for analysis of glucose, cortisol, insulin,
epinephrine and norepinephrine. Blood samples were taken before induction of
anaesthesia (preinduction), and at 1, 3 and 4 hours after surgical incision. Serum glucose
concentration was measured by the glucose oxidase enzymatic method; the absorbance of
glucose was read at 500nm. Plasma cortisol, insulin, epinephrine and norepinephrine
concentrations were measured by enzyme linked immunosorbant assay (ELISA)
technique; the absorbance of the solution were read within 10 minutes, using a microplate
reader set to 450 nm and a reference wavelength between 620 nm and 650 nm.
Three of the forty-four patients enrolled in the study had complications in the
perioperative period leaving 41 patients for analysis. In group I (GAR), 1 patient
developed postoperative haemorrhage and required a repeat surgery, while in group II
(CSEA), 2 patients were excluded on account of severe hypotension with SBP <80 mmHg
which required the administration of intravenous ephedrine. Group I (GAR) consisted of
21(51.22%) patients and Group II consisted of 20(48.78%) patients. There were
no differences between the two groups regarding age, height, weight, body mass index
and packed cell volume (p>0.05).
The preinduction glucose concentration was similar in both groups (GAR
4.88 ±0.51 versus CSEA 4.90 ±1.04 mmol/L, p =0.933). The mean glucose was
significantly higher in the GAR group than in CSEA group, at 1 hour after incision
(6.09 ±1.19 versus 4.58 ±1.31 mmol/L, p <0.001), at 3 hours (6.77±1.39 versus
5.38 ±1.789 mmol/L, p = 0.012), and at 4 hours after incision (GAR 7.28 ±1.44 versus
CSEA 6.17 ±1.69 mmol/L, p =0.034).
The mean cortisol was similar in both groups, at preinduction (GAR 13.32 ±6.44
versus CSEA 17.84 ±10.42 g/dl, p =0.299), and at 1 hour after incision (GAR
30.29 ±14.41 versus CSEA 23.42 ±10.33 g/dl, p =0.156). The mean cortisol was higher
in the GAR group than in CSEA group, at 3 hours after incision (34.16 ±11.88 versus
23.15 ±12.10 µg/dl, p =0.072), but not significant, and at 4 hours after incision (GAR
38.94 ± 10.60 versus CSEA 19.96 ±11.32 g/dl, p =0.018) which was significant.
The mean insulin concentration was similar in the GAR and CSEA groups, at preinduction
(4.63 ±0.49 versus 4.88 ±0.53 uIU/ml, p =0.304), and at 24 hours after incision (GAR
5.04 ±1.06 versus CSEA 4.69 ±2.24 uIU/ml, p =0.403).
The mean epinephrine was similar in the GAR and CSEA groups, at preinduction
(19.68 ±13.84 versus 24.36 ±18.03 pg/ml, p =0.641), at 1 hour after incision (GAR
25.44 ±17.91 versus CSEA 26.39 ±19.22 pg/ml, p =0.867), at 3 hours after incision (GAR
20.56 ±17.67 versus CSEA 21.68 ±14.77 pg/ml, p =0.743), and at 4 hours after incision
(GAR 22.86 ±11.22 versus CSEA 18.30 ±11.37 pg/ml, p =0.707).
There was no significant difference in mean norepinephrine concentration between
GAR and CSEA groups, at preinduction (38.24 ±16.14 versus 65.76 ±23.77 pg/ml, p
17
=0.480), at 4 hours after incision (GAR 46.56 ±19.51 versus 72.38 ±20.31 pg/ml, p
=0.359). The mean norepinephrine, however, was significantly higher in CSEA group
than in GAR group, at 1 hour after incision (GAR 54.52 ±19.45 versus CSEA
219.31 ±42.85 pg/ml, p =0.015), and at 3 hours after incision (GAR 27.00 ±18.86 versus
CSEA 115.29 ±39.91 pg/ml, p =0.045).
The mean heart rate and mean arterial blood pressure were significantly higher in the
general anaesthesia group during the study period.
This study has demonstrated that the mean glucose, cortisol levels, blood pressure
and heart rate were significantly lower in patients who received combined spinal epidural
anaesthesia than those who received general anaesthesia relaxant technique during major
gynaecological surgery. The mean norepinephrine levels, however, were higher in the
combined epidural anaesthesia group than in the general anaesthesia group.

THE NEUROENDOCRINE RESPONSE TO GYNAECOLOGICAL SURGERY: COMPARING THE MODULATING EFFECT OF TWO ANAESTHETIC TECHNIQUES