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Spinal anesthesia : Smaller needles, higher levels

par Mardirosoff, Chahé;Dumont, Lionel ;Massaut, Jacques
Référence Regional Anesthesia, 22, 2 SUPPL., page (13)
Publication Publié, 1997

Article révisé par les pairs

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Résumé :

Introduction : The use of small gage pencil-point spinal needles may lead to sacral maldistribution of local anesthetics if the direction of the side - port opening is caudal and injection rate too slow (1). The purpose of this study was to observe if rapid injection of local anesthetics via a 27G Whitacre needle led to higher sensitive block levels compared to a 24G Sprotte needle. Methods : 20 ASA I or II patients scheduled for elective orthopedic surgery of the lower limbs were randomized in two groups after 1KB approval and verbal consent. The two groups received a standard infusion line with 500ml lactate-Ringer solution. The first group received a combined spinal epidural anesthesia in a sitting position at L2 - L3 interspace via a 17G Tuohy-Weiss needle with loss of resistance to air after which a 27G long spinal needle with the side-port in a cephalad direction was inserted and 3ml heavy bupivacaine were injected in 10 seconds after obtaining free flow of CSF. The second group received spinal anesthesia in the same position with a 24G Sprotte needle with the side-port in a cephalad direction and received the same amount of heavy bupivacaine in 10 seconds. In the two groups, patients were placed supine four minutes after the spinal. All patients were monitored with one lead ECG, SpO2 and N1BP. Sensitive block levels were measured in the midline with ether every five minutes from 5 to 40 minutes after the spinal. Blood pressure was closely monitored and a 20% decrease or a blood pressure < 100 nunHg was treated by atropine or ephedrine or phenylephrine depending on the heart rate. Results : The two groups were demographically comparable. Sensitive block levels were significantly higher in the 27G group from 20 to the end of the measurements. At 20 minutes, mean levels in thoracic dermatomes were : 5.6 in the 27G group and 7.8 in the 24G group ( p=0.024 / Mann-Whitney). At 25 minutes, , mean levels in thoracic dermatomes were : 5.1 in the 27G group and 7.1 in the 24G group ( p=0.015 ). At 30,35 and 40 minutes, mean levels in thoracic dermatomes were : 5 in the 27G group and 7 in the 24G group ( p<0.025 ). The use of vasopressors was not different between the two groups. Conclusions : We observed higher sensitive block levels with a mean difference of two dermatomes when we performed fast injection through a 27G Whitacre spinal needle compared to a 24G Sprotte needle with a large side-port. Better mixing of local anesthetics is achieved at the expense of a higher sensitive Mock level.