Hyperbaric Bupivacaine Versus Hyperbaric Prilocaine 2% for Cesarean Section Under Spinal Anesthesia

Hyperbaric Bupivacaine Versus Hyperbaric Prilocaine 2% for Cesarean Section Under Spinal Anesthesia: a Randomised Clinical Trial

Over the past 15 years, cesarean delivery is most commonly performed under spinal anesthesia using hyperbaric bupivacaine which provides an adequate sensory and motor block. Despite effective surgical anesthesia, bupivacaine is associated with long duration motor block and dose-dependent maternal hypotension potentially harmful for the fetus. Prilocaine with its new 2% hyperbaric formulation (HP), developed recently, showed rapid onset of action and faster regression of motor block compared to other local anesthetics without noteworthy side-effects when used intrathecally. The aim of this randomized, multicenter, powered clinical trial is to investigate whether HP may be an efficient alternative to hyperbaric bupivacaine for scheduled caesarean delivery under spinal anesthesia, with more rapid rehabilitation and less adverse effects. Our hypothesis is that hyperbaric prilocaine offers shorter motor block and more rapid rehabilitation than bupivacaine.

Hyperbaric bupivacaine 0.5% will be administered at the dose of 10 mg intrathecally associated with 100 µg of morphine and 2.5 µg of sufentanyl.

Hyperbaric prilocaine 2% will be administered at the dose of 50 mg intrathecally associated with 100 µg of morphine and 2.5 µg of sufentanyl.

The dose of 10 mg of hyperbaric bupivacaine will be administered to one of two groups intrathecally and the quality of sensory and motor block as well as side-effects will be observed at precise time points.

The dose of 50 mg of hyperbaric prilocaine will be administered to one of two groups intrathecally and the quality of sensory and motor block as well as side-effects will be observed at precise time points.

Time to regression of motor block is the time between maximal blockade (score 1, as evaluated by the Modified Bromage scale), and no blockade (score 6). Degree of motor blockade is assessed before and 10, 15, 20 minutes after spinal anesthesia, then every 15 minutes until the end of surgery, and thereafter, every 30 minutes until complete regression of motor block

Level of Sensory block is assessed as loss of sensation to cold, and represents the dermatomal level under which anesthesia is effective. It is measured every 2 minutes after spinal anesthesia during 15 minutes, then every 5 minutes until the end of surgery, thereafter, once 30 minutes until total regression of sensory block (T12-S1). A dermatome is the area of skin that is supplied by a single spinal nerve - Dermatome levels : C5-C8 for Cervical levels and T1-T4 for Thoracic levels. To perform cesarean section loss of cold sensation at a dermatome of at least T4 has to be obtained. The results are expressed as the number of patients reaching each dermatomal level from T4 and above (see below) as maximal sensory level, this is a usual outcome used to evaluate the quality of anesthesia.

Evaluation at every 2 minutes after spinal anesthesia during 15 minutes, then every 5 minutes until the end of surgery, and thereafter, every 30 minutes until total regression of sensory block (T12-S1).

Time of installation of the motor block (time between spinal injection and maximum motor block of 1, as evaluated by the Modified Bromage scale). Degree of motor blockade is assessed before and 10, 15, 20 minutes after spinal anesthesia

From spinal injection of the local anesthetic to bilateral T4 level and during surgery (average 1 hour)

Arterial blood pressure will be measured at every 1 minute during the first 15 minutes, then at every 2.5 minutes until the end of surgery, and at every 20 minutes in the Post Anesthesia Care Unit (PACU). A low blood pressure (hypotension) is defined as a systolic blood pressure lower than 20% or more than the basal blood pressure (Systolic blood pressure before spinal anesthesia)

Time for the patients to be able to walk in their room then in the hallway without any assistance for the first time.

All patients will be asked to rate their satisfaction about anesthetic technique during surgery and in the arrival in the Post Anesthesia Care Unit (PACU). Satisfaction evaluated by Visual analog scale (0 cm= very unsatisfied and 10cm = very satisfied)

Maternal rehabilitation is evaluated at postoperative Day1, postoperative Day 2 and postoperative Day 3. Evaluation by Visual analog scale (0 cm= very poor and 10cm = excellent)

Evaluation from 15 minutes after spinal injection to the end of surgery, then every 4 hours for 24 hours, then once a day for 3 days (score 0=no symptom; 1=symptom with no necessary treatment; 2=symptom present and treated)

Evaluation of apparition of TNS at postoperative Day 1, postoperative Day 2, postoperative Day 3 and postoperative Day 15. TNS are defined as pain and/or dysesthesia occurred after complete release of sensory block at the gluteal level, at the thighs and at the legs.

Pain levels will be determined at incision, baby delivery, peritoneal and skin closure, every 5 minutes during surgery, and thereafter every 4 hours for 24 hours. Visual analog pain score (scale = 0 no pain; 10 = worst pain imaginable). Patient will receive additional analgesic treatment above VAS>3.

Newborn Apgar score assessed at 1, 5, 10 minutes after baby extraction. The Apgar score is determined by evaluating the newborn baby on five simple criteria on a scale from 0 to 2, then summing up the five values thus obtained. The overall resulting score ranges from 0 to 10 ( 0-3 : severely depressed, 4-6 : Moderately depressed and 7-10 : Excellent condition). The five criteria are summarized using words chosen to form an abbreviation (Appearance, Pulse, Grimace, Activity, Respiration).

Newborn Methemoglobinemia (MetHb) will be assessed at delivery by cordal blood sample, as a routine control in obstetrics, and expressed as a percentage of total hemoglobinemia. Methemoglobinemia (MetHb) is a blood disorder in which an abnormal amount of methemoglobin (hemoglobin in the form metalloprotein) is produced. This specific type of of Hemoglobin carries oxygen through your blood but doesn't release it to the cells.

Newborn umbilical pH will be assessed at delivery by cordal blood sample, as a routine control, and expressed as standard value

Satisfaction ranged between 1 (totally unsatisfied) to 4 (totally satisfied) assessed at the end of surgery

Satisfaction ranged between 1 (totally unsatisfied) to 4 (totally satisfied) assessed at postoperative Day 3

Inclusion Criteria : American Society of Anesthesiologists physical status (ASA) < III Age 18-40 year Body Weight <110 kg Height between 160 and 175 cm Gestational age>37 SA Elective cesarean delivery Singleton pregnancy Non complicated pregnancy Signed informed consent obtained prior to any study specific assessments and procedures Exclusion Criteria: Twin pregnancy History of 2 cesarean section or more Diabetes and gestational diabetes Placenta praevia Congenital foetal abnormality Intrauterine growth retardation Patient in labour Membrane rupture Known allergy to local anaesthetics Standard contraindications to neuraxial block. Disagreement of the patient Neurological impairment Gestational low blood pressure Pre eclampsia and eclampsia

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Goffard P, Leloup R, Vercruysse Y, Fils JF, Gautier PE, Kapessidou Y. Comparison of equipotent doses of intrathecal hyperbaric prilocaine 2% and hyperbaric bupivacaine 0.5% for elective caesarean section: A prospective, randomised, controlled, two-centre clinical trial. Eur J Anaesthesiol. 2022 Mar 1;39(3):227-235. doi: 10.1097/EJA.0000000000001548.