الفهرس 
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Abstract
The percentage of C-section, one of the most common surgeries continues to increase all over the world. C-sections should be done when normal labor is contraindicated. When medically indicated, C-section can prevent maternal and perinatal adverse effects.
The percentage of C-section performed under RA has increased greatly over the last 20 years. Unless there is a contraindication, RA is the method of choice for C-section in most countries. Disadvantages of SA for C-section include the following, high prevalence of hypotension, intrapartum nausea and vomiting, post dural puncture headaches, and limited duration of action. Various efforts have been directed at prediction of maternal hypotension to enhance the plan of its management.
PI is a new parameter measuring the pulsatility of blood in the extremities. It is an easy, economic and non-invasive technique of measuring peripheral perfusion determined by the ratio of pulsatile to non-pulsatile blood flow in the extremities. Baseline peripheral vascular tone may have effect in the incidence of hypotension after SA.
EC estimates changes in thoracic resistance or impedance, using four skin electrodes. EC can separate the alteration in impedance caused by the circulation, partly caused by the change in arrangement of the RBCS during the cardiac cycle. The electrical and impedance wave are analyzed, and then used to measure haemodynamic parameters such as CO, SVV, and SVR. Pre-anesthetic SVV, CO, and SVR would allow identification of patients at a relatively high risk of haemodynamic fluctuation during SA.
Increased sympathetic drive before SA is associated with intraoperative hypotension during C-section. The positional change in BP can be taken as the assessment of degree of sympathetic activity and hence can predict intraoperative hypotension under SA.
The aim of this study was to estimate the correlation of each of the PI, SVV, PVR and positional changes in haemodynamic (HR and BP) measured before SA in prediction of hypotension during C-section.
After approval of the Local Ethical Research Committee and having written informed consent from all patients, 107 parturient scheduled for C-section under SA were enrolled in this prospective observational study
In order to fulfill selection criteria, every patient was subjected to a careful pre-anaesthetic assessment. Patients were given 30 mL of sodium citrate. Upon arrival in the OR, patients were positioned on an operating table in supine position with left lateral tilt 15 to 30 degree and allowed to rest and calm down for 5 minutes. An 18-gauge IV cannula was inserted under LA. Routine monitors were attached. Baseline haemodynamic measurements were made including HR and BP. The PI was assessed from the pulse oximeter probe connected to the left index finger in supine position. Baseline CO, SVV and SVR were measured noninvasively using EC ICON. Positional changes in haemodynamic (HR and BP) in lateral and sitting position.SA was administered using 2.2 ml of hyperbaric bupivacaine 0.5% and 25 μg fentanyl. Rapid IV coload of lactated Ringer’s solution was given for the first 1 L, and then maintenance fluids were limited to 10 ml/kg/hour. Block height was assessed using ice swap and considered adequate if at the T4 level. Patients were monitored for (Systolic, diastolic and mean) BP and HR every 2 minutes till the delivery of baby and every 3 minutes thereafter. Hypotension was defined as a decrease of > 20% from baseline SBP after SA as and was treated if MABP below 60 mm Hg immediately with IV administration of 10 mg ephedrine.
Incidence of hypotensive cases during C-section was 57%.
Of socio-demographic characteristics age has significant negative correlation with BP, while there was no significant correlation between BP and WT as well with HT. There was significant negative correlation between BP and gravity .Pre-operative noninvasive measurements (PI, SVR and SVV) had significant negative correlation with BP.
Of haemodynamic parameters at supine position HR had significant negative correlation with BP while, other measurements (SBP, DBP and MABP) had no significant correlation with BP.
Changes from supine to lateral position and to sitting position in (HR, SBP, DBP and MABP) had significant negative correlation with BP
Multivariate logistic analysis to assess factors affecting occurrence of hypotension three models were significant in prediction of occurrence of hypotension. Model one including (PI ,SVR, SVV and HR in supine position) ,the significant predictor was SVR .Model two including changes from supine to lateral position (HR, SBP, DBP and MABP) ,the significant predictor were (∆HR, ∆DBP and ∆MABP) Model three including changes from supine to sitting position (HR ,SBP, DBP and MABP, the significant predictor were (∆HR and ∆DBP).