الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
The stress response is the name given to the hormonal and metabolic changes which follow injury or trauma.
The stress response to surgery is characterized by increased secretion of pituitary hormones and activation of the sympathetic nervous system. The changes in pituitary secretion have secondary effects on hormone secretion from target organs. For example, release of corticotrophin from the pituitary stimulates cortisol secretion from the adrenal cortex. Arginine vasopressin is secreted from the posterior pituitary and has effects on the kidney. In the pancreas, glucagon is released and insulin secretion may be diminished. The overall metabolic effect of the hormonal changes is increased catabolism which mobilizes substrates to provide energy sources, and a mechanism to retain salt and water and maintain fluid volume and cardiovascular homeostasis. Hypothalamic activation of the sympathetic autonomic nervous system results in increased secretion of catecholamines from the adrenal medulla and release of norepinephrine from presynaptic nerve terminals. Norepinephrine is primarily a neurotransmitter, but there is some spillover of norepinephrine released from nerve terminals into the circulation. The increased sympathetic activity results in the well-recognized cardiovascular effects of
Summary
80
tachycardia and hypertension. In addition, the function of certain visceral organs, including the liver, pancreas and kidney, is modified directly by efferent sympathetic stimulation and/or circulating catecholamines.
Stress-induced changes in postoperative organ function may be associated with the development of perioperative complications.
Modulation of the stress response to surgery could reduce postoperative morbidity and be a key factor in improving outcome, shortening the length of the hospital stay as well as lowering the total cost of patient care. Laparoscopic cholecystectomy has gained in popularity because the surgical incision required is small compared with that for open cholecystectomy, but surgical stress responses remain an important feature of the laparoscopic approach.
Distension of the peritoneum and increased arterial carbon dioxide tension, due to absorption of carbon dioxide, can contribute to the stress response during this procedure.
Various pharmacological agents like nitroglycerine, β blocker, and opioids are used to provide hemodynamic stability during pneumoperitoneum, but they have their own disadvantages.
Summary
81
Both magnesium and dexmedetomidine are known to inhibit catecholamine and vasopressin release and attenuate hemodynamic response to laryngoscopy and pneumoperitoneum.
The purpose of this study was to compare between the effect of intravenous dexmedetomidine and magnesium sulphate on the hemodynamic changes and hormonal responses to tracheal intubation and pneumoperitoneum during laparoscopic cholecystectomy under general anesthesia.
Patients were randomly allocated to one of three equal
Groups. All received general anesthesia technique.
The Magnesium group (Group M):
Patients received a bolus dose of 30 mg/kg magnesium sulphate 10% added to isotonic normal saline 0.9% to complete the volume to 50 ml and given as intravenous infusion over a 10- minute period before induction of anesthesia. This was followed by a continuous infusion of magnesium sulphate 10 mg/kg/h added to isotonic normal saline 0.9% to complete the volume to 50ml using a syringe pump till the removal of the gall bladder.
Summary
82
The Dexmedetomedine group (Group D):
Patients received a bolus dose of 0.5μg/kg dexmedetomedine in 50 ml of isotonic normal saline 0.9% and given as intravenous infusion over a 10-minute period before induction of anesthesia. This was followed by a continuous infusion of 0.4μg/kg/h in 50 ml of isotonic normal saline 0.9% using a syringe pump till the removal of the gall bladder.
The Control group (Group C):
Patients received the same volumes of isotonic normal saline 0.9% in the same regimen.50 ml of normal saline 0.9% is infused intravenously over a 10- minute period before induction of anesthesia. This is followed by a continuous infusion of 50 ml of normal saline 0.9% every hour using a syringe pump till the removal of the gall bladder.
The following was monitored intraoperatively till 90 min at the PACU: blood pressure, heart rate, Pain score, sedation score, level of serum blood cortisol, RBS, time to 1st request analgesic ,inflation pressure.
The study showed that dexmedetomidine was more effective in attenuating cardiovascular and hormonal response to PP when compared with magnesim sulphate.