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784: Effects of Epidural Analgesia on the Feto-Placental Blood Flow as Evidenced by Doppler Velocimetry
Posters
784. Effects of epidural analgesia on the feto-placental blood flow as evidenced by doppler velocimetry S.N. El-Tallawy College of Medicine, King Saud Uviversity, Anesthesia, Riyadh, Saudi Arabia This study was designed to evaluate effect epidural analgesia on placental perfusion, fetal blood flow. Eighty parturients were enrolled randomly into four groups. The unknown local anesthetic was bupivacaine 0.125% in group 1; bupivacaine 0.25% (group 2); ropivacaine 0.125% (group 3) or ropivacaine 0.25% (group 4). Fentanyl 80 mg was added in all groups. Assessments included hemodynamics, pain assessment, onset and duration of analgesia, top-up doses and motor blockade. Doppler velocimetry included umbilical artery pulsitility indices UAPI and middle cerebral artery pulsitility indices MCAPI. The hemodynamic parameters were significantly decreased in all groups after analgesia except group 3 showed variable changes. Also, all groups showed significant reduction in pain scores with the best pain relief in groups (2, 4) followed by groups (1, 3). The onset of analgesia started rapidly group 4, followed by groups (2, 1, 3) respectively. The longest durations of analgesia observed in group 2, followed by groups (1, 4, 3) respectively. The number of top up doses were comparable, but the total volume of local anesthetics was the lowest in group 2 followed by groups (1, 4, 3) respectively. The incidence motor blockade was significant in group 2, followed by group (1, 4, 3) respectively. Doppler indices were improved after epidural analgesia with the best readings was observed 45 minutes. But, during uterine contractions, both UAPI and MCAPI were slightly changed but still better than the readings before epidural analgesia. Also, the highest decreases in UAPI and highest increases in MCAPI were observed in the bupivacaine groups in comparison to ropivacaine groups. Conclusion: Ropivacaine was associated with insignificant motor blockade and bupivacaine was characterized by prolonged duration of action. The Doppler indices were improved significantly after epidural analgesia Acknowledgement: The author would like to acknowledge the CMRC for supporting this research.
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Obstetrics
133
284. Mechanics of dural membrane puncture by Touhy needles and epidural catheters: a quantitative experimental model N. Daniel1, S. Behl1, A. Fisher2, T. Wauchob1, P. Barclay1 Women’s NHS Foundation Trust, Anaesthesia, Liverpool, UK, 2Royal Liverpool University Hospital, Clinical Engineering, Liverpool, UK
1Liverpool
Background and Aims: Accidental dural puncture is a complication of epidural analgesia in labour with an incidence of 0 to 2.6%. In these instances, around 70% of patients develop a postdural puncture headache syndrome secondary to persistent CSF leakage causing reduced CSF pressure. No systematic quantitative experimental study of the mechanics of dural puncture has been previously reported. Here, a novel methodology is described using a realistic tissue model and a robust experimental regime. The forceto-puncture profile in time at constant velocity is reported separately for three types of Touhy needle and their respective catheters. Method: Tuohy needles and catheters manufactured by Braun, Vygon and Portex were studied. Chicken skin, dissected free of subcutaneous tissue was stretched across a circular form and mounted on the base-plate of a Nene tensile testing instrument. In a series of trials (n ⫽ 48), needles and needle-plus-catheters were advanced at constant velocity to 5mm beneath the tissue surface. The force-to-puncture was measured using a Nene load cell and data stored for post hoc analysis. Video records were made of tissue deflection at the contact point. Data were processed using MatLab. Maximum force-to-puncture estimates were inferred from data smoothing spline representations. Results: 1. Very significant differences were found in force-to-puncture values between needles of same gauge: Vygon ⬍ Braun ⬍ Portex (1.76, 1.90, 2.40N); 2. No trial with epidural catheters (at extension from needle up to 5mm) achieved puncture. Conclusions: 1. The model is robust, sensitive and relevant; 2. Force-to-puncture varies significantly between 3 makes of Touhy needle; 3. Catheters are unlikely to puncture dural membrane.
784. Effects of epidural analgesia on the feto-placental blood flow as evidenced by doppler velocimetry S.N. El-Tallawy College of Medicine, King Saud Uviversity, Anesthesia, Riyadh, Saudi Arabia This study was designed to evaluate effect epidural analgesia on placental perfusion, fetal blood flow. Eighty parturients were enrolled randomly into four groups. The unknown local anesthetic was bupivacaine 0.125% in group 1; bupivacaine 0.25% (group 2); ropivacaine 0.125% (group 3) or ropivacaine 0.25% (group 4). Fentanyl 80 mg was added in all groups. Assessments included hemodynamics, pain assessment, onset and duration of analgesia, top-up doses and motor blockade. Doppler velocimetry included umbilical artery pulsitility indices UAPI and middle cerebral artery pulsitility indices MCAPI. The hemodynamic parameters were significantly decreased in all groups after analgesia except group 3 showed variable changes. Also, all groups showed significant reduction in pain scores with the best pain relief in groups (2, 4) followed by groups (1, 3). The onset of analgesia started rapidly group 4, followed by groups (2, 1, 3) respectively. The longest durations of analgesia observed in group 2, followed by groups (1, 4, 3) respectively. The number of top up doses were comparable, but the total volume of local anesthetics was the lowest in group 2 followed by groups (1, 4, 3) respectively. The incidence motor blockade was significant in group 2, followed by group (1, 4, 3) respectively. Doppler indices were improved after epidural analgesia with the best readings was observed 45 minutes. But, during uterine contractions, both UAPI and MCAPI were slightly changed but still better than the readings before epidural analgesia. Also, the highest decreases in UAPI and highest increases in MCAPI were observed in the bupivacaine groups in comparison to ropivacaine groups. Conclusion: Ropivacaine was associated with insignificant motor blockade and bupivacaine was characterized by prolonged duration of action. The Doppler indices were improved significantly after epidural analgesia Acknowledgement: The author would like to acknowledge the CMRC for supporting this research.
•
Obstetrics
133
284. Mechanics of dural membrane puncture by Touhy needles and epidural catheters: a quantitative experimental model N. Daniel1, S. Behl1, A. Fisher2, T. Wauchob1, P. Barclay1 Women’s NHS Foundation Trust, Anaesthesia, Liverpool, UK, 2Royal Liverpool University Hospital, Clinical Engineering, Liverpool, UK
1Liverpool
Background and Aims: Accidental dural puncture is a complication of epidural analgesia in labour with an incidence of 0 to 2.6%. In these instances, around 70% of patients develop a postdural puncture headache syndrome secondary to persistent CSF leakage causing reduced CSF pressure. No systematic quantitative experimental study of the mechanics of dural puncture has been previously reported. Here, a novel methodology is described using a realistic tissue model and a robust experimental regime. The forceto-puncture profile in time at constant velocity is reported separately for three types of Touhy needle and their respective catheters. Method: Tuohy needles and catheters manufactured by Braun, Vygon and Portex were studied. Chicken skin, dissected free of subcutaneous tissue was stretched across a circular form and mounted on the base-plate of a Nene tensile testing instrument. In a series of trials (n ⫽ 48), needles and needle-plus-catheters were advanced at constant velocity to 5mm beneath the tissue surface. The force-to-puncture was measured using a Nene load cell and data stored for post hoc analysis. Video records were made of tissue deflection at the contact point. Data were processed using MatLab. Maximum force-to-puncture estimates were inferred from data smoothing spline representations. Results: 1. Very significant differences were found in force-to-puncture values between needles of same gauge: Vygon ⬍ Braun ⬍ Portex (1.76, 1.90, 2.40N); 2. No trial with epidural catheters (at extension from needle up to 5mm) achieved puncture. Conclusions: 1. The model is robust, sensitive and relevant; 2. Force-to-puncture varies significantly between 3 makes of Touhy needle; 3. Catheters are unlikely to puncture dural membrane.