Comparative Study of the Combination of Different Modes of Administration of Local Anesthetics in Labor Analgesia

The investigators have design an observational study to know the anesthetic consumption in terms of rescue analgesia (Patient Controlled Epidural Analgesia (PCEA) and manual boluses) of the combination of different modes of administration of local anesthetic in the epidural space during labor analgesia offered by the new version of the CADD® infusion pump.

Also in this pump the anesthetic can be administered across a system of standard flow (40-250ml/h) or of high flow (40-500ml/h), what according to studies can influence the diffusion epidural of the anesthetic and therefore the level of sensitive blockade.

The study is designed with healthy patients, first-time mothers, in childbearing dynamics, term pregnancy and nullipary. The epidural technique was performed with dose test of 3ml of bupivacaína 0,25 % with vasoconstrictor and a manual bolus of 0,1ml/Kg of ropivacaína 0,2% with fentanilo 5ug/ml.

As soon as the informed consent about the epidural anesthesia was signed, the patient was informed of the possibility of taking part in the study and there is offered him the sheet of information of the patient. So in one group they were administered Programed Intermittent Epidural Boluses (PIEB) and in other group continuous Epidural Infusion (IC) plus PIEB according to the usual clinical practice of each anesthesiologist. In both cases the perfusion was of ropivacaína 0,1 % more fentanilo 2ug/ml, so that in the first group it was administered PIEB of 10ml every hour and in the second group a continuous infusion to 3ml/h plus PIEB of 7ml every hour. Also if during the period of dilatation an AVE (Analogical Visual Escale) greater than or equal to 4 appeared (inadequate analgesia) the patient could administer a 5ml PCEA bolus of the same solution (interval of closing of 20min and maximum dose for hour of 15ml), as it is done in according to the usual clinical practice. And if after two boluses of PCEA the analgesia was still ineffective a clinical bolus of 4ml of lidocaína to 1 % was administered by the anesthesiologist.

In addition, in the group that was administered only PIEB, the standard infusion system was compared with the high-flow infusion system.

In all patients it was evaluated and noted on the epidural record sheet the intensity of the pain as the analogical visual scale (AVE), the grade of motor blockade as the modified scale of Bromage and the sensitive level in different periods of time. Also registered the total doses of anesthetic, the way of the childbearing finishes, the Apgar of the newborn, the grade of maternal satisfaction and the side effects. Also through the software of the pump it was verified if the patient had been administered rescue analgesia (PCEA or clinical boluses).

Eligibility Criteria:
Inclusion Criteria:

* Pregnant women in work of established labor and contractions of moderate intensity
* Age between 18 and 45 years
* ASA I and II
* Nulliparity
* Pregnancy to term (\> 36semanas)
* The only fetus of cephalic presentation
* Cervical dilation between 2-5cm

Exclusion Criteria:

* Maternal systemic illness (Diabetes Mellitus, arterial Hypertension, Preeclampsia. . )
* Major or equal weight to 100 Kg
* Less height of 150cm
* Duration of the equal or major childbearing to 24h
* Administration of opioides parenterales in 2-4h before to performing of the epidural
* Contraindication for neuroaxial analgesia
* Precedents of allergy or hypersensitivity to anesthetic local