BJA Advance Access published online on October 15, 2008
British Journal of Anaesthesia, doi:10.1093/bja/aen294
Comparison of hyperbaric and plain articaine in spinal anaesthesia for open inguinal hernia repair
1 Department of Anaesthesiology and Intensive Care Medicine
2 Maria Hospital, Helsinki University Hospital, Helsinki, Finland
* Corresponding author: Department of Anaesthesia, Eye Hospital, Helsinki University Central Hospital, Haartmaninkatu 4, PO Box 220, 00029 HUS, Finland. E-mail: helena.kallio{at}hus.fi
Accepted for publication September 7, 2008.
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Abstract |
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Background: Fast onset and short duration are prominent properties of the amide-type local anaesthetic articaine. Similar to bupivacaine, a hyperbaric solution of articaine may produce faster onset and shorter duration of spinal anaesthesia than a plain solution.
Methods: Patients undergoing open inguinal hernia repair received in random order articaine 84 mg in either hyperbaric (HyperA, n=49) or plain solution (PlainA, n=48) intrathecally. A blinded observer tested the dermatomal spread (pinprick) and motor block (Bromage scale).
Results: Median (range) onset time to the T10 dermatome was 2 (2–8) (n=46) and 6 (2–30) min (n=39) (P<0.001), and the duration of the sensory block at (or above) the T10 dermatome was 86 (39–148) and 69 (15–118) min (P=0.007), in Groups HyperA and PlainA, respectively. Peak sensory block was greater in Group HyperA T4 (L2–C2) than in Group PlainA T8–T7 (L3–T3) dermatome, median (range), P<0.001. Spread of the block to the cervical dermatomes associated with hypotension occurred in three patients of Group HyperA (one patient C2 and two C4). The sensory block resolved to the S2 dermatome significantly faster in Group HyperA, 2.5 (1.5–4.5) h, than in Group PlainA, 3.5 (2.0–4.5) h (P<0.001). Median duration of the motor block was significantly shorter in Group HyperA, 2.0 (1.3–3.5) vs 3.0 (1.5–4.0) h (P<0.001).
Conclusions: Hyperbaric articaine 84 mg had a faster onset and shorter duration of spinal anaesthesia than the plain solution.
Keywords: anaesthetic techniques, regional, spinal; anaesthetics local, articaine; surgery, ambulatory
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Introduction |
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Articaine, an amide-type local anaesthetic is nowadays commonly used in dentistry.1 2 It has been found safe in preclinical toxicology testing3 and its low degree of toxicity has been verified to result from ester hydrolysis of a side chain on the molecule.4 Articaine has been found useful also in other types of regional anaesthetic techniques, including spinal anaesthesia.5 Since the 1970s, published reports of its successful clinical use in spinal anaesthesia include more than 2000 patients.6–11 Presently, its use in spinal anaesthesia is limited to only a few European countries (e.g. Germany, The Netherlands, and Finland).
Spinal block properties of hyperbaric articaine have earlier been found to be similar to that of hyperbaric lidocaine,7 and we, therefore, recently compared hyperbaric articaine 60, 84, and 108 mg in spinal anaesthesia for day-case surgery of the lower extremities.9 The 84 mg dose was deemed the most suitable for day-case surgery, because this dose produced most reliably a fast spinal block with 60 min duration of the block at, or above, the T10 dermatome, and with rapid recovery without anaesthesia-related neurologic sequelae.
Hyperbaricity speeds up onset and shortens the duration of the spinal block performed with tetracaine,12 ropivacaine,13 14 and bupivacaine.15 16 As the plain solution of articaine is already slightly hyperbaric,17 18 it may be possible that it behaves similarly as a glucose-containing hyperbaric articaine solution. We therefore compared the plain articaine solution with a clearly hyperbaric articaine solution (glucose 75 mg ml–1, 7.5%) for spinal anaesthesia.
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Methods |
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After receiving Institutional Ethics Committee and National Agency for Medicines approval and patients’ written informed consent, 100 adult patients (
80 yr, ASA class I–III, and BMI32 kg m–2) undergoing open mesh inguinal hernia repair according to Lichtenstein were enrolled and randomized to receive spinal anaesthesia with articaine (Ultracain® ohne Adrenalin, 40 mg ml–1, Aventis, Frankfurt am Main, Germany) 84 mg either in a hyperbaric (HyperA) or in a plain solution (PlainA). Spinal anaesthesia was the routine anaesthetic technique for open inguinal hernia repair in our day-care clinic and exclusion criteria were patient’s refusal to receive spinal anaesthesia, radicular lower back symptoms, and communication problems.
Monitoring in the operating theatre and post-anaesthesia care unit (phase 1 PACU) consisted of ECG, pulse oximetry, and non-invasive arterial pressure. No premedication was given, and the patients were blinded regarding their group assignment throughout the study. A stratified sealed envelope method was used for randomization. The anaesthetist performing the block prepared the articaine solution in the operating theatre just before injecting it. The hyperbaric (glucose 75 mg ml–1, 7.5%) solution was prepared by adding 0.7 ml of 300 mg ml–1 glucose (30%) to 2.1 ml (84 mg) of plain articaine solution. Consequently, the volumes were 2.8 ml in Group HyperA and 2.1 ml in Group PlainA. The density of plain articaine 20 mg ml–1 at 37 ºC is 1.0084,13 indicating that the density of the 40 mg ml–1 plain solution, used by us, is also slightly greater than that of the cerebrospinal fluid (CSF). The patient was positioned in strict horizontal lateral decubitus position (spine adjusted horizontally using a spirit level) and operating side dependent, and after a skin wheal with lidocaine 10 mg ml–1 (1%), the anaesthetist performed the subarachnoid puncture with a 27 G pencil point needle (Pencan®, B. Braun Melsungen, Germany) at the L3–4 interspace in the midline. Identification of the intended interspace was aided by noting the location of the L4 spinous process on Tuffier’s line (line connecting the superior aspects of the iliac crests). The drug solution was injected at a rate of 
1 ml over 10 s, with barbotage (0.2 ml once) before and after finishing the injection. Then, the patient was turned into the supine position (operating table adjusted as needed) and a group-blinded investigator was allowed to enter the room. Both of the study-designated assessors were specifically trained in the dermatomal assessment with pinprick of the spread of the block and in grading motor block of the lower extremities according to a modified Bromage scale, i.e. 0, full movement; 1, inability to raise extended leg, can bend knee; 2, inability to bend knee, can flex ankle; and 3, no movement. Pinprick dermatomal testing of both sides of the body was performed at 2 min intervals until 10 min, then at 5 min intervals until 30 min, and thereafter at 15 min intervals until 90 min. Thereafter, the interval was 30 min, until sensational recovery of the S2 dermatome. The motor block was assessed at 5 min intervals until 30 min and, thereafter, at the same intervals as the tests for sensory block.
Before spinal anaesthesia 200–300 ml of Ringer’s acetate solution was given i.v. Arterial hypotension and bradycardia were treated according to clinical needs. Fentanyl was given for pain during surgery and if it did not alleviate all pain sensations, general anaesthesia with propofol, remifentanil, and laryngeal mask airway was induced. Before closing the wound, the surgeon infiltrated the tissue layers covering the mesh with 20 ml of ropivacaine 7.5 mg ml–1 (0.75%).
In phase 1 PACU, the patient was placed in a semi-recumbent position (upper body 30° up). Etoricoxib 90–120 mg and acetaminophen 500–1000 mg were given orally (together with half a glass of water). Thereafter, pain in phases 1–2 PACUs was treated with additional doses of acetaminophen or oral oxycodone, as needed. After complete recovery of the motor block and recovery of the sensation of the S2 dermatome, the patient was allowed to ambulate in phase 2 PACU. The patient had to be painfree (or almost painfree), non-nauseated, drink and eat, and pass urine before discharge home.
On the first and seventh days after operation, a structured telephone interview was performed by one of the investigators (blinded to group assignment). The interview included questions on the anaesthesia, surgery, pain treatment, occurrence of any headache (position-dependent or not), occurrence of backache with or without radiation in the buttocks and thighs, and their satisfaction with the anaesthetic technique.
Power analysis
The sensory block at or above T10 dermatome was 25% shorter with hyperbaric than with plain bupivacaine.14 15 In our previous study with hyperbaric articaine, the mean (SD) duration of the T10 sensory block was 71 (28) min.9 With a similar assumed difference in duration of the block at least T10 dermatome, we calculated that 39 patients per group would be required with a power of 80% and a level of significance of 5%.
Statistical analyses
Data on weight, height, and BMI are given as mean (SD). Other continuous variables are reported as median (range), except for age mean (range). Continuous normally divided variables were compared using t-test and Mann–Whitney U-test was used if the data were not normally distributed. Categorical variables are expressed as median (range), and they were compared between the two groups with the Mann–Whitney U-test. Repeated measures two-way ANOVA was used for comparison of variables between the groups over time, e.g. sensory pinprick anaesthesia or motor block. Binominal data are given as numbers (%) and were compared using the 
2 test or Fisher’s exact test when appropriate. A P-value of <0.05 was considered statistically significant. Statistical analyses were performed using SigmaStat®, version 3.5 (Systat Software, Inc., Point Richmond, CA, USA) and graphs were designed based on the same data using SigmaPlot®, version 10, from the same firm.
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Results |
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The patients and surgical characteristics were similar in the two groups (Table 1). Three of the 100 study patients were excluded from the analyses: one in Group HyperA because the patient had received a non-steroidal anti-inflammatory analgesic for premedication by mistake, one in Group PlainA because of failed spinal block, and one because he had been previously treated in Group HyperA half a year earlier. Two patients in Group HyperA and five patients in Group PlainA had to be given general anaesthesia: in six of them because of too limited spread of the sensory block for the planned surgery and in one patient (HyperA) because his surgery was changed from Lichtenstein operation to a resection of the urinary bladder which lasted longer than the anticipated hernia repair. These seven patients received rescue fentanyl before general anaesthesia and their parameters are included in the analyses.
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The subarachnoid puncture was performed at the L3–4 (n=83), L2–3 (n=13, seven HyperA and six PlainA patients), or L4–5 (one HyperA patient) interspace at the midline (except for two HyperA patients, paramedially). The pencil point needle had to be replaced by a 27 G cutting tip needle in three HyperA and one PlainA patients. Bone was contacted in 10 HyperA and nine PlainA patients during puncture attempts. A paraesthetic sensation was registered in six HyperA and three PlainA patients, but neither the patients in whom bone was met during the puncture nor those who experienced paraesthesia reported any neurologic sequelae on the first or seventh day interviews.
Sensory block
The sensory block spread to the T10 dermatome faster and was maintained at at least T10 longer in Group HyperA than in Group PlainA (Table 2). The sensory block reached the cervical dermatomes in three patients in Group HyperA only (Fig. 1) and spread significantly more extensively in Group HyperA than in Group PlainA (Table 2). The duration of sensory block, from injection to the recovery of S2 dermatome, was significantly shorter in Group HyperA than in Group PlainA (Fig. 2).
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Motor block
Complete bilateral motor block (Bromage 3) developed within 5 min in 81 patients (82% in HyperA vs 85% in PlainA) and in another 13 patients within 10 min. Three HyperA patients did not develop complete motor block (their maximal extension of the sensory block was T12 in two patients and L2 in one patient). The period from local anaesthetic injection to complete motor function recovery was shorter in Group HyperA than in Group PlainA (Table 2, Fig. 3).
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Medication in the operating theatre
Patients were given less rescue fentanyl in Group HyperA than in Group PlainA (P=0.005). Median dermatomal spread of the sensory block when patients received fentanyl did not differ significantly between the groups, T8–7 (L2–T4) vs T9 (L3–T4), in HyperA and PlainA, respectively. In Group HyperA, fewer patients [8 (16%) vs 21 (44%), P<0.001] needed rescue fentanyl significantly later 60 (15–75) vs 30 (15–65) min after spinal injection, P=0.010.
In Group HyperA, 17 patients, including all those with the sensory block spread to cervical dermatomes, and nine patients in Group PlainA needed ephedrine 5–35 mg for treatment of hypotension during surgery. In Group HyperA, the need for ephedrine was associated with greater extension of the sensory block, T2 (T5–C2) than in those in whom ephedrine was not needed, T4 (L2–T2), P=0.001. However, in Group PlainA, spread of the sensory block did not differ significantly between those who needed ephedrine, T11 (L3–T3), and those who did not, T7 (T12–T3). If ephedrine was needed, the sensory block was significantly more extensive in Group HyperA than in Group PlainA, T2 (T5–C2) vs T11 (L3–T3), P<0.001. The total doses of ephedrine did not differ between the groups, 10 (5–30) and 5 (5–35) mg, in HyperA and PlainA, respectively.
For bradycardia (32–58 beats min–1), either atropine 0.3–1 mg or glycopyrrolate 0.2–0.4 mg was given to 15 patients in both groups (Table 3). There was no significant difference in the extension of sensory block within the groups whether anticholinergics were given or not [in Group HyperA, T3 (L2–T2) vs T4 (T12–C2) and in Group PlainA, T9 (L3–T3) vs T7 (T12–T3)].
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Medication in phase 1 PACU
In phase 1 PACU, all patients received anti-inflammatory non-steroidal analgesics prophylactically. Either fentanyl i.v. or oxycodone (i.v. or i.m.) was given to eight patients in Group HyperA and to 13 patients in Group PlainA. None of the patients experienced nausea or vomiting during phase 1 PACU stay.
Observation and additional medication in phase 2 PACU
One HyperA patient had a prolonged stay in phase 2 PACU unit because of nausea and she received antiemetics i.v. One patient of group HyperA had pain with VAS score 5 in phase 1 PACU and he received 10 mg i.v. and 8 mg i.m. of oxycodone. As he was still in pain at phase 2 PACU, he received oxycodone 10 mg perorally and ondansetron 4 mg i.v. twice for nausea. He had to stay overnight in the hospital (discussed later). Also two PlainA patients were nauseated, but they did not need any rescue medication. The other patients (n=93) did not experience nausea. Nine patients in Group HyperA and 12 patients in Group PlainA received oxycodone perorally.
The median time from spinal injection until voluntary urination (n=93) did not differ between the groups, 4.3 (3.0–9.7) and 4.3 (3.1–7.5) h, although the sensory block wore off significantly more quickly in Group HyperA (median 2.5 h) than in Group PlainA (median 3.5 h), P<0.001. Three patients in Group HyperA needed urinary bladder catheterization: one of them for 10 days because of urinary bladder operation, another needed catheterization in phase 2 PACU, and the third had some difficulties passing urine because of prostate hyperplasia and he needed catheterization on the first day after operation. The time of spontaneous urination was not registered in one patient of both groups. One patient (HyperA) suffering from prostate hyperplasia had some minor voiding difficulties after surgery, and on the next day, he was examined and catheterized in the emergency department of the hospital.
Stay in hospital
Three patients had to stay in the hospital overnight (one night), one (HyperA) because of pain, another (HyperA) had wound haemorrhage and needed reoperation within the same day under general anaesthesia. The third patient (PlainA) had no escort or company at home after operation and stayed overnight in the hospital.
Two patients had to stay in hospital for two nights. The operation of one patient was converted to laparotomy because of more extensive surgery than planned (a 10 cm pouch of the urinary bladder comprised the inguinal hernia). His spinal anaesthesia with hyperbaric articaine had reached the T3 dermatome in 4 min, but general anaesthesia was needed because of prolonged surgery. The other patient (PlainA) stayed because of pain treatment. He had also general anaesthesia because the sensory block did not spread above the T12 dermatome, and the ilioinguinal nerve had to be cut during surgery.
Interviews after operation
Pain and side-effects on days 1 and 7 after operation are reported in Table 4. Operative site pain was a dominating symptom in 32% of the patients on day 1 (VAS score 
5 in movements). Transient unilateral radiating symptoms in the lower extremities occurred in two patients of Group PlainA. Posture-dependent post-dural puncture headache (PDPH) was reported by one patient of both groups (Table 4), but they did not need any epidural blood patch. Other types of headache were reported by two patients in Group HyperA and one patient in Group PlainA. One patient in both groups was very dissatisfied because of failed block, which required general anaesthesia. One patient in Group HyperA was very dissatisfied because of too extensive block combined with urinating difficulties after operation (discussed earlier). Overall, the patients were very satisfied (60%) or satisfied (35%) with their anaesthesia.
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PDPH means posture-dependent headache, which is worsened by standing up and alleviated by lying down |
Discussion |
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The results of this study indicate that the duration of the spinal block with a clearly hyperbaric solution of articaine is shorter than with a plain (slightly hyperbaric) solution. We reconfirm the difference between hyperbaric and plain solutions previously reported with tetracaine,12 ropivacaine,13 14 and bupivacaine.15 16 The onset of the block was very rapid and in most instances, the block with the hyperbaric solution would have been adequate for surgery in 2–4 min after the injection. These findings are similar to those obtained with 84 mg hyperbaric articaine in our earlier dose-finding study9 and similar to those with 80 mg hyperbaric articaine.11
The most plausible explanation for the shorter duration of spinal block after the use of a hyperbaric solution is the fact that the spread of the local anaesthetic was significantly more extensive within the subarachnoid space and, therefore, diluted articaine is rapidly bound over a large tissue area followed by rapid absorption and elimination. In several patients, the sensory block with hyperbaric articaine spread too cephalad and was associated with hypotension, as expected.19 This was at least in part a consequence of our study protocol, which demanded a supine horizontal position of the patient immediately after the injection of the local anaesthetic. With the table in horizontal position, the hyperbaric local anaesthetic solution will flow down the lumbar lordotic curve and up the thoracic kyphotic curve according to gravity and depending on the dose, usually resulting in a sensory block to the mid- or upper thoracic dermatomes.20 21 Individual variation in the spinal column curves may in part explain the maximal extension of the local anaesthetic to either lumbar or thoracic dermatomes.
The density of plain articaine 40 mg ml–1 solution has not been reported in the literature, but the density of a plain articaine 20 mg ml–1 solution at 37°C is slightly greater than that of CSF.17 18 The density of a more concentrated articaine solution is obviously still greater and assumingly hyperbaric even without the addition of glucose. However, an exact difference between the density of a local anaesthetic solution and that of CSF to make a solution explicitly behave in a hyperbaric fashion is difficult to determine, partly because the density of various plain solutions varies and the plain solutions are often slightly hypobaric at 37°C and partly also because the density of CSF in man varies individually and it is also influenced by gender22 and pregnancy.23
In the studies of factors which may determine the spread of spinal anaesthesia in adults, it has been shown that 0.8% glucose concentration in the bupivacaine 5 mg ml–1 solution, which raises the density by only 0.0009,24 seems to modify the solution just enough to make it spread like a hyperbaric solution.24–26 We assume that such a difference in density would probably be smaller than the extrapolated difference in density between articaine 40 mg ml–1 and CSF at 37°C.
Supporting the theoretical assumption of a difference in densities, typical hyperbaric behaviour of plain articaine 40 mg ml–1 was evident by observing almost as rapid initial spread of the sensory block to the T10 dermatomal level in many patients as was seen in Group HyperA.
All, except five patients, were discharged home on the day of surgery. Since our criteria of discharge include successful voluntary voiding, the patients were discharged late (median 6 h) after recovery from the sensory block (median 3 h). The incidence of posture-dependent PDPH was 2%, which is comparable with the incidence reported when similar types of spinal needles have been used,27 and with that found in our previous study with articaine.9 None of the patients developed such neurologic symptoms which could be classified as transient neurologic symptoms (TNSs) after spinal anaesthesia with articaine.28 This is in accordance with reported rareness of TNSs after articaine spinal anaesthesia in other studies.6–11 As yet, there are only two reported possible cases of TNSs.10 11 Transient backache and one-sided aching radiating to the lower extremity occurred in a few patients. These symptoms had vanished by day 7 after surgery. Only in the patient in whom the ilioinguinal nerve was unintentionally cut, pain treatment with pregabalin and non-steroidal anti-inflammatory analgesics continued for a longer period under the supervision of the pain clinic physicians.
In conclusion, the onset of spinal anaesthesia to the T10 dermatome was faster and durations of sensory and motor block were shorter with a clearly hyperbaric solution of articaine than with a plain solution. However, with the patient in the horizontal position, the cephalad spread of anaesthesia with the clearly hyperbaric solution was in several patients more extensive than would be useful. The dose of 84 mg of hyperbaric articaine seems suitable for open inguinal hernia repair.
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This study was supported by Helsinki University Hospital EVO funds.
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Acknowledgements |
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We thank the staff of the day-surgery unit of Maria Hospital, Helsinki University Hospital, for their co-operation and Minna-Maria Mattila, RN, Department of Anaesthesiology and Intensive Care Medicine, for valuable technical assistance.
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