RESUMO
Background: Neuraxial anesthesia is considered as the gold standard in the control labor of pain. Its variants are epidural analgesia and combined spinal-epidural analgesia. Few studies, as yet, have investigated the duration of labor as a primary outcome. Some authors have suggested that combined spinal-epidural analgesia may reduce labor duration but at the moment the benefit of shortening labor is uncertain. The main aim of this study was to compare combined spinal-epidural with epidural analgesia in terms of their effect on duration of stage I labor, maternal, and neonatal outcomes. Methods: A prospective cohort study was conducted. Parturients who requested analgesia at cervical dilatation <6 cm were included. Analgesia was either epidural with low concentration levobupivacaine or combined spinal epidural with subarachnoid sufentanil. The primary outcome was the length of stage I labor. Onset and quality of analgesia, mode of delivery, effects on uterine activity and use of oxytocin, fetal heart rate abnormalities and uterine hyperkinesia, maternal, and neonatal complications were also considered. Results: We enrolled 400 patients: 176 in the combined spinal-epidural group and 224 in the epidural group. Patients in the two treatment groups were similar with regard to demographic characteristics, parity, and incidence of obstetric comorbidities, labor induction, oxytocin infusion, Bishop score, and Visual Analogue Score (VAS) at analgesia request. Duration of stage I labor did not differ, at 195 (120-300) minutes for both the groups (p = .7). Combined spinal-epidural was associated with less reduction in uterine contractility after initial administration: 15.34 versus 39.73%, (p < .001) and with delayed need for oxytocin, at dilations of 7 ± 2.5 cm versus 6. ± 2.7, (p = .002). Onset of analgesia was quicker for combined spinal-epidural analgesia: 31 versus 20%, with VAS <4 after 5 minutes, (p < .001); and lower VAS scores after initial analgesia administration. No differences were found in the other outcomes. Conclusions: Combined spinal-epidural with subarachnoid sufentanil may not reduce the duration of stage I labor, but in our study it appeared to affect uterine contractility less. It also had a more rapid onset and was more effective, without any concomitant increase in maternal or neonatal complications.
Assuntos
Analgesia Epidural , Analgesia Obstétrica/métodos , Raquianestesia , Primeira Fase do Trabalho de Parto/efeitos dos fármacos , Adulto , Analgesia Epidural/métodos , Anestesia Epidural/métodos , Raquianestesia/métodos , Estudos de Coortes , Terapia Combinada , Feminino , Frequência Cardíaca Fetal/efeitos dos fármacos , Humanos , Primeira Fase do Trabalho de Parto/fisiologia , Trabalho de Parto/efeitos dos fármacos , Trabalho de Parto/fisiologia , Gravidez , Resultado da Gravidez , Adulto JovemRESUMO
OBJECTIVE: To define how to monitor and limit CO(2) rebreathing during helmet ventilation. DESIGN: Physical model study. SETTING: Laboratory in a university teaching hospital. INTERVENTIONS: We applied pressure-control ventilation to a helmet mounted on a physical model. In series 1 we increased CO(2) production (V'CO(2)) from 100 to 550 ml/min and compared mean inhaled CO(2) (iCO(2),mean) with end-inspiratory CO(2) at airway opening (eiCO(2)), end-tidal CO(2) at Y-piece (yCO(2)) and mean CO(2) inside the helmet (hCO(2)). In series 2 we observed, at constant V'CO(2), effects on CO(2) rebreathing of inspiratory pressure, respiratory mechanics, the inflation of cushions inside the helmet and the addition of a flow-by. MEASUREMENTS AND RESULTS: In series 1, iCO(2),mean linearly related to V'CO(2). The best estimate of CO(2) rebreathing was provided by hCO(2): differences between iCO(2),mean and hCO(2), yCO(2) and eiCO(2) were 0.0+/-0.1, 0.4+/-0.2 and -1.3+/-0.5%. In series 2, hCO(2) inversely related to the total ventilation (MVtotal) delivered to the helmet-patient unit. The increase in inspiratory pressure significantly increased MVtotal and lowered hCO(2). The low lung compliance halved the patient:helmet ventilation ratio but led to minor changes in MVtotal and hCO(2). Cushion inflation, although it decreased the helmet's internal volume by 33%, did not affect rebreathing. A 8-l/min flow-by effectively decreased hCO(2). CONCLUSIONS: During helmet ventilation, rebreathing can be assessed by measuring hCO(2) or yCO(2), but not eiCO(2). It is directly related to V'CO(2), inversely related to MVtotal and can be lowered by increasing inspiratory pressure or adding a flow-by.