الفهرس 
List of abbreviationsOnly 14 pages are availabe for public view
 |  | from | 105 |  |  |
| | | from | 105 | | |
Abstract
Many anesthetists prefer to give spinal anesthesia for women who will undergo cesarean section. Spinal-induced hypotension represents incidence of about 55%, so it is the most frequent complication. Moreover, hypotension is hazardous for the mother and the baby as it can cause loss of consciousness, aspiration, and even cardiac arrest for the mother and placental hypoperfusion, which can lead to fetal problems.
There are several methods to minimize maternal hypotension after spinal anesthesia like fluids, medications, and physical methods like positioning, leg bindings, lateral uterine displacement using a 15º tilt which is essential in parturients to prevent the ‘supine hypotension syndrome’ where compression of the inferior vena cava by the gravid uterus leads to reduced venous return and subsequent hypotension. Preloading is commonly administered but it has controversial results.
Ephedrine has been used as a vassopressor with spinal anaesthesia, but its position has been challenged because of potential complications that include supraventricular tachycardia, tachyphylaxis and fetal acidosis.
Many other drugs have been studied to reduce the incidenced hypotension which results primarily from decreased vascular resistance, increased baroreceptor activity or induction of the BezoldJarischReflex (BJR).
A review of randomized trials on the use of vasopressors with spinal anaesthesia analysed seven studies, and concluded that clinical effects were similar between ephedrine and phenylephrine in terms of prevention and treatment of hypotension.
Owczuk et al(199) found that ondansetron 8 mg decreased the incidence of bradycardia and hypotension after spinal anaesthesia.
Sahoo et al(1) concluded that Ondansetron 4 mg, given intravenously 5 min before subarachnoid block reduced hypotension and vasopressor use.
White et al(200) observed that i.v. administration of granisetron 50 μg/kg was efficacious in suppressing bradycardia and hypotension associated with the BJR.
Tsikouris et al(6). found that granisetron decreased heart rate and BP changes occurred during the head-up tilt table test due to BJR.
Rashsd and Farmawy(201) compared between granisetron and ondansetron as regard their hemodynamic effects on parturients underoing C.S under spinal anesthesia. But, it was found that granisetron had no effects on the hemodynamic variables, and this is in agreement with Mowafi et al(202) .
Our study was the first to compare between ondansetron ,granisetron and phenylephrine in the prevention of spinal induced hypotension in patients undergoing caesarean section. 150 Patients were randomly assigned to either: (i) group P : (n: 50) received 4 mg of I.M. .phenylephrine immediately after induction of spinal anaesthesia;(ii)group O: (n: 50) received 4 mg of I.V. ondansetron diluted in 10 mL of normal saline; and (iii) group G: (n: 50) received 4 mg of I.V. granisetron 5 minutes before spinal anaesthesia.
We found that phenylephrine produced significantly higher SBP, lower HR than the other two groups in the period of 10-20 minutes of intra-operative time with on difference between G, O groups in the same time period. Before and after this time , no difference between the three groups.
We concluded that the three drugs successfully prevented spinal induced hypotension with phenylephrine use resulted in higher SBP but more incidence of nausea than granisetron or ondansetron.
We recommend to do large scale studies to get more detailed results.