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Year : 2014  |  Volume : 8  |  Issue : 1  |  Page : 26-31  

A comparison of thoracic spinal anesthesia with low-dose isobaric and low-dose hyperbaric bupivacaine for orthopedic surgery: A randomized controlled trial

1 Department of Anesthesiology, Faculty of Medicine Nova Esperança, João Pessoa, Paraíba; Director of the Institute for Regional Anesthesia, Brazil
2 Director of the Institute for Regional Anesthesia, Brazil

Date of Web Publication15-Mar-2014

Correspondence Address:
Luiz Eduardo Imbelloni
Rua Francisco Diomedes Cantalice, 21/802, 58045 210-João Pessoa, Paraíba
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0259-1162.128900

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Background: The thoracic spinal anesthesia was first described in 1909 and recently revised for various surgical procedures. This is a prospective study aims to evaluate the parameters of the thoracic spinal anesthesia (latency, motor block and paresthesia), the incidence of cardiovascular changes and complications comparing low doses of isobaric and hyperbaric bupivacaine.
Materials and Methods: A total of 200 orthopedic patients operated under spinal anesthesia were included in this study. Spinal anesthesia was between T9-T10, with a 27G cutting point or pencil tip in lateral or sitting. Spinal anesthesia was performed with 0.5% bupivacaine isobaric or hyperbaric. Patients remained in cephalad or head down position 10-20° for 10 minutes. We evaluated the demographics, analgesia, and degree of motor block, incidence of paresthesia, bradycardia, hypotension, anesthesia success and neurological complications.
Results: All patients developed spinal and there was no failure. The solution did not affect the onset of the blockade. The duration of motor block was greater than the sensitive with isobaric. The duration of sensory block was greater than the motor block with hyperbaric solution. The incidence of paresthesia was 4%, with no difference between the needles. The incidence of hypotension was 12.5% with no difference between the solutions. There was no neurological damage in all patients.
Conclusion: The beginning of the block is fast regardless of the solution used. By providing a sensory block of longer duration than the motor block hyperbaric bupivacaine is reflected in a better indication. Thoracic spinal anesthesia provides excellent anesthesia for lower limb orthopedic surgery

Keywords: Thoracic spinal anesthesia, complications, local anesthetic, bupivacaine isobaric, hyperbaric bupivacaine

How to cite this article:
Imbelloni LE, Gouveia MA. A comparison of thoracic spinal anesthesia with low-dose isobaric and low-dose hyperbaric bupivacaine for orthopedic surgery: A randomized controlled trial. Anesth Essays Res 2014;8:26-31

How to cite this URL:
Imbelloni LE, Gouveia MA. A comparison of thoracic spinal anesthesia with low-dose isobaric and low-dose hyperbaric bupivacaine for orthopedic surgery: A randomized controlled trial. Anesth Essays Res [serial online] 2014 [cited 2022 Jan 22];8:26-31. Available from:

   Introduction Top

Spinal anesthesia methods are preferred for orthopedic procedures. It is a simple and quick procedure, with a short turnover time, and provides good surgical anesthesia. In the recovery room, patients are seen to be more alert, with less nausea and vomiting and discomfort. Significant adverse events such as permanent neurological injury or infections are very rare. In 1909, Thomas Jonnesco proposed puncture in two segments of the thoracic spine: Puncture (T 1 -T 2 ) and low punch (T 12 -L 1 ), since the average puncture (T 5 -T 6 ) was more difficult to achieve. [1] Anatomical study of the cervical spine in cadavers showed that the spinal cord was pushed along the needle forming a tent, and that this tent protected the spinal pia mater during spinal puncture preventing spinal cord injury. [2] Recently the anatomy of the thoracic spinal canal was investigated with magnetic resonance of imaging (MRI). [3],[4],[5] A study with 300 patients with low thoracic spinal puncture has been shown that the incidence of paresthesia of 6.6% [6] was nearly half (12%) of lumbar puncture, [7] without neurological sequelae. In 636 patients with low thoracic spinal anesthesia with low doses of bupivacaine showed a rapid onset and low incidence of hypotension with faster recovery of the blockade without any neurological sequelae. [8]

After the two initial studies [6],[8] with thoracic spinal puncture, several orthopedic surgeries were performed in our unit with puncture at the level of T 10 . Previous studies [9],[10] have compared the clinical effects of hyperbaric and isobaric solutions of bupivacaine using single lumbar injection with patients in the supine position. The conclusions were that the cephalad spread produced by the hyperbaric solutions was generally significantly greater than the isobaric solutions. Likewise, hypotension was also greater with the hyperbaric solutions because of the more extensive sensory and sympathetic denervation. [9],[10]

We hypothesized that low dose of isobaric bupivacaine administered as thoracic spinal anesthesia for orthopedic procedures would provide more stable hemodynamics, more motor block and fewer side effects as compared the same dose hyperbaric bupivacaine. In this double-blinded randomized controlled study, we aimed to compare the anesthesia quality, the differences in sensory and motor blockade, and complications during thoracic spinal anesthesia of a patient group undergoing orthopedic procedure with 10 mg isobaric bupivacaine to those of another patient group treated with 10 mg hyperbaric bupivacaine. The primary outcome of our study was complete regression of motor and sensitive block.

   Materials and Methods Top

After the study protocol had been approved by the local Ethics Committee, written informed consent was obtained from all patients, aged over 18 years, with American Society of Anesthesiologists (ASA) physical status I-II, who scheduled to elective orthopedic surgery, which did not require orthopedic table.

Patients with serious central nervous system disorders, severe cardiopulmonary disease, blood volume deficits, coagulation disorders, diabetes or peripheral neuropathies, allergy to local amide anesthetics, and patients who refused to participate were excluded from the study.

We conducted pre-anesthetic evaluation. Each patient underwent a fasting period of up to six hours. The patients were not premedicated. Heart rate, non-invasive arterial blood pressure, and pulse oximetry were monitored in the operating room, and baseline values were obtained before initiation of spinal anesthesia. All patients were given supplemental oxygen via a nasal cannula at a rate of 3 L/min -1 throughout the intervention and operation. An 18G peripheral venous catheter was inserted into the patients in dorsal hand for hydration with lactated Ringer's and administration of drugs during the procedure. The patients received 500 ml of hydroxyethyl starch 6% in sodium chloride (Voluven ® ) during the surgical intervention.

After injection of 3 ml (7.5 mg) decreased mean arterial pressure was significantly lower with the hyperbaric (30%) than the isobaric (18%). [11 ] In the present study it was to be used as a fixed dose of 10 mg, and the sample size was calculated based on the significance level of 95% and 10% accuracy by obtaining a number of 169 patients. We chose 200 patients for guaranty against data loss.

The data collection form included age, gender, weight, height, presence or absence of paresthesia, location of paresthesia and presence or absence of a discernible spinal block.

The patients were then randomly allocated to two groups via a computer-generated random number table. The anesthesiologist performing the assessment and the patients were blinded to the local anesthetic used. Fentanyl 1 μg/kg and midazolam 1 mg was given before spinal anesthesia. Patients with fracture of the distal femur received from 5 to 10 mg of ketamine administered intravenously before being placed in position for spinal anesthesia instead of fentanyl.

After cleansing the skin with alcoholic chlorhexidine, the skin of the puncture site was infiltrated with 1% lidocaine. Group 1 (n = 100) received 10 mg of 0.5% isobaric bupivacaine (Cristαlia Produtos Quνmicos e Farmacκuticos Ltda) while Group 2 (n = 100) received 10 mg of 0.5% hyperbaric bupivacaine (Cristαlia Produtos Quνmicos e Farmacκuticos Ltda). In both groups, spinal anesthesia was induced in a lateral decubitus or sitting position at the T 9 -T 10 interspaces using a 27G cut needle (B. Braun Melsungen SA) without introducer or 27G pencil point needle (B. Braun Melsungen SA) with introducer. After the appearance of the LCS local anesthetic was injected. The study solutions were administered with 15 seconds into the subarachnoid space. After the spinal injection, the patients were placed in a supine position, and their heads were tilted up 30° in isobaric group and head up 30° in hyperbaric group, and where remained for 10 minutes. In case of failure after thoracic injection, a new spinal block was performed in the lumbar region and the patient was excluded from the study.

A blinded observer assessed the dermatome level of sensory blockade bilaterally along the midclavicular line using analgesia to pinprick with a stylet of the needle (27G). Motor block was evaluated bilaterally in the lower limb according to a modified Bromage scale (0 = no motor block; 1 = inability to raise extended legs; 2 = inability to flex knees, able to move feet; or 3 = inability to flex ankle joints). Sensory and motor blocks were recorded at 10 minutes after spinal injection.

Onset time to T 10 (umbilical region) level of sensory block, maximum sensory block level, time to full recovery of sensory block and time for the Bromage score to become zero (recovery of motor block) were recorded.

Hypotension was defined as a decrease of more than 30% from the baseline systolic arterial blood pressure and treated with IV boluses of 2 mg ethylephrine. Bradycardia was defined as heart rate <50 bpm (beat per minute) and treated with atropine 0.50 mg. Intraoperative side effects (nausea, vomiting and itching) were followed by both observing and questioning the patients.

Following the procedure all patients received ketoprofen 100 mg of and dipyrone 40 mg/kg in 50 ml of saline and all patients received a lumbar block (psoas compartment or inguinal block) and para-sacral (sciatic nerve block) block with 50 ml of 0.2% bupivacaine with an insulated needle and a nerve stimulator. To evaluate the quality of the postoperative analgesia was not the objective this study.

Patients were followed-up for 1 st , 3 rd , 10 th and 30 th days postoperatively over the phone to gather information regarding the presence of headache, temporary neurological symptoms, or back pain. Headache located in the occipital or frontal region was classified as postdural puncture headache (PDPH) if worsened when the patient was in the sitting position, was. Back pain was considered a transitory neurological symptom (TNS) if the patient experienced pain and/or decreased sensitivity in the back, buttocks, and legs after recovery, which resolved in 72 hours. All patients were examined between 30 and 35 days after puncture by the anesthesiologist. If there were any complaints or concerns, the patient would be referred to a neurologist. Serious complications such as epidural hematoma, infection, or permanent nerve injury were evaluated.

Statistical analysis

For comparison between groups was used Chi-square test () and Fischer's exact test. For comparison of means between two groups we used the Student t test and Mann-Whitney test. In the case of quantitative variables the assumption of normality were checked by Lilliefors test. To correlate the dose with the sensory and motor block Pearson correlation test was used. A value of P < 0.05 was considered as a statistically significant difference.

   Results Top

A total of 200 patients were enrolled in the study and no patient was excluded. No difference was observed between the groups with respect to gender, age, height and weight [Table 1].
Table 1: Demographic data (mean (SD))

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The observed overall incidence of paresthesia associated with thoracic spinal needle insertion was 4%. There were no significant difference between the types of needle, the position of puncture and needle insertion [Table 2]. Paresthesia occurred in the right thigh of two patients; left thigh in one, two thighs in four, left limb in two and both limbs in one. All paresthesias were transient and without residual sequel.
Table 2: Paresthesia in accordance with the needle, the puncture position and inserting the needle

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The onset of analgesia was fast and comparable among the two solutions. The duration of motor block was significantly higher with isobaric whereas the duration of sensory block was significantly higher with the hyperbaric solution, with significant inverse correlation (value - P < 0,001) [Table 3]. But there was no difference in the total duration of the blockade (sensory + motor) between the solutions. There were significant differences between the different degrees of motor block between the two solutions, with the isobaric being higher.
Table 3: Characteristics of neuraxial anesthesia techniques

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[Table 3] also shows the number of patients with a motor blockade of grade 1, 2 or 3. There were significant differences between the two solutions, being higher with the isobaric bupivacaine.

We observed nine (4.5%) patients with bradycardia without significant difference [Table 4]. Those who developed bradycardia did not require atropine. The incidence of hypotension was 12.5% and no significant difference between the two solutions [Table 4]. Patients who developed hypotension required only one dose of 2 mg of ethilephrine. No patient developed nausea, vomitting or pruritus during the surgical procedure.
Table 4: Complication

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Cephalad spread of sensory blockade, assessed by pinprick, was more homogeneous with hyperbaric bupivacaine (range, T 7 -T 10 ) than the isobaric bupivacaine (range, T 4 -T 10 ), but the mode of the dispersion was the same in both solutions [Table 5].
Table 5: Sensory block levels

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No patient developed headache. No patient experienced pain on local anesthetic injection. All patients developed spinal anesthesia; there were no patchy blocks. No patient was obtained paresthesia complained of neurological symptoms at follow-up. There were no serious complications such as epidural hematomas, infection, or permanent nerve injuries in all patients.

   Discussion Top

Bupivacaine is anesthetic often used in spinal anesthesia for orthopedic surgery. Spinal anesthesia can be performed with local anesthetics at different doses and baricity. The thoracic spinal puncture at T 9 -T 10 for orthopedic surgeries showed a rapid onset of action, regardless of bupivacaine solution (isobaric or hyperbaric), decrease in the incidence of hypotension with low incidence of paresthesia. In this study, we demonstrated that 10 mg hyperbaric bupivacaine provided a motor block of shorter duration and sensory block of longer duration than the 10 mg isobaric bupivacaine. Dose of intrathecal 10 mg bupivacaine are sufficient to provide effective anesthesia in orthopedic surgeries.

Still as a consequence of the difference of the growing rhythm between the spinal column and the medulla, one has the increasing distance of the medullary segments from the corresponding vertebrae. So, in the adult, the vertebrae T 11 and T 12 correspond to the five lumbar medullary segments. To know what level the spinous process of the vertebra corresponds to the medullary segment we have the following rule: Between C 2 and T 10 we add two to the spinal process of the vertebra to find out the lumbar medullary segment while from T 11 and T 12 they correspond to the five lumbar segments. The process of L 1 corresponds to the five sacral segments. The anatomical data described in this paragraph explain that a puncture at T 10 is justified because the nerves of the lower limbs derive from the medulla at this level and the lower limbs will be easily blocked.

There are several studies in the literature that compare different solution and the same doses for orthopedic surgeries. Lumbar injection was found a longer installation with isobaric bupivacaine compared with hyperbaric bupivacaine. [9],[10] Different other studies with lumbar puncture, [12] in this study the onset analgesia with the isobaric solution was the same as with the hyperbaric solution. This can be explained by the lower amount of CSF in the chest region in relation to the lumbar segment [13] and also roots thoracic be thinner compared to segments above and below this level. [14] Thus, there is less anesthetic dilution per segmental unit of distance from the site of injection, and the roots are easily blocked due to their small size, both factors predicting efficient blockade of these segments. The long latency with the isobaric solution in the lumbar spinal anesthesia was not observed in this study.

The use of hypobaric, isobaric or hyperbaric solution in the spinal anesthesia has shown that each solution has its own particular onset time, spread and motor block duration. Understanding spinal anesthesia, we demonstrated that the duration of sensory block may be larger than the motor block, depending on the injected solution. [15 ] In this study all groups were immediately placed in the supine position, showing that the duration of sensory block was significantly higher than the motor block with hyperbaric bupivacaine and the duration of motor block was significantly higher than the sensory block with isobaric bupivacaine. However, both solutions, the same doses, showed the same block length, around 2:30 min. Because both solutions have the same duration, it is preferable hyperbaric solutions by providing a longer lasting sensory blockade without the unpleasant motor blockade.

Classic teaching is that the sympathetic block in spinal anesthesia is spread in at least two segments cranially more than sensory block. [16] Unnecessary high blockade can lead to adverse hemodynamic changes and in extreme cases, a significant pressure drop and severe bradycardia, and therefore the level of sensory block should be adequate as possible with the needs of the surgery.

In laparoscopic surgeries, severe hypotension that required treatment with ethilephrine occurred in 38.5% of patients who received conventional-dose of bupivacaine, whereas only 14.2% in the low-dose group developed hypotension. [17] In this study with 10 mg of isobaric or hyperbaric, the cephalad spread was controlled by the position and was practically the same (T 10 ), resulting in a low incidence of hypotension (12.5%) and bradycardia (4.5%). In this study, it is clear that lowering the spinal dose improves hemodynamic stability. Thus the incidence of hypotension in orthopedic patients was similar to that in the study with laparoscopic surgery and thoracic puncture. [17]

The complete motor block was obtained in 93% of patients with isobaric and 78% with hyperbaric bupivacaine. The total duration of the block (sensitive and motor blocks) was practically the same with either solution, but isobaric solution provided a longer motor block than the hyperbaric one.

The anatomical images generated by MRI have shown that the spinal cord is relatively protected in its thoracic part because the size of the subarachnoid space varies between 3 and 8 mm. [3],[4],[5] A study of 300 patients undergoing thoracic spinal puncture was not observed with any neurological sequelae. [6] The same way, utilizing thoracic spinal anesthesia in 636 patients for a variety of surgical procedures did not produce one single case of permanent neurologic damage. [8] In the present study, in 200 patients who underwent orthopedic surgeries, no permanent neurologic damage was observed. This confirms that spinal anesthesia proposed by Jonnesco is safe. [1]

During attempts to insert a spinal needle into the subarachnoid lumbar space, patients occasionally experience paresthesias, a reported frequency of 13.6%. [18] A study of 300 patients undergoing thoracic spinal puncture reported a 6.6% incidence of paresthesia. [6] In 636 patients of spinal anesthesia under thoracic spinal puncture for a variety of procedures the incidence of paresthesia was 6.1%. [8] In this study of orthopedic patients the overall incidence of paresthesia was 4%, smaller than in both studies. The paresthesias were transient and disappeared in the immediate postoperative period.

   Conclusion Top

The objective of the use of spinal thoracic anesthesia in orthopedic patients was: (1) to have a faster installation, verifying the eventual difference between the two solutions, isobaric and hyperbaric, (2) to provide a longer sensory block than the motor block, (3) to reduce collateral effects such as hypotension and bradycardia and (4) to provide a spinal anesthesia without neurologic complication. All these objectives were reached with the thoracic spinal anesthesia with low dose of spinal anesthetics. Because hyperbaric bupivacaine solution provides a longer sensitive block as compared to the isobaric solution it is better suited for thoracic spinal anesthesia. Thoracic spinal anesthesia provides excellent anesthesia for lower limb orthopedic surgery.

   References Top

1.Jonnesco T. Remarks on general spinal analgesia. Br Med J 1909;2:1396-401.  Back to cited text no. 1
2.Orrison WW, Eldevik, Sackett JF. Lateral C1-2 puncture for cervical myelography. Part III: Historical, anatomic, and technical considerations. Radiology 1983;146:401-8.  Back to cited text no. 2
3.Imbelloni LE, Ferraz-Filho JR, Quirici MB, Cordeiro JA. Magnetic resonance imaging of the spinal column. Br J Anaesth 2008;101:433-4.  Back to cited text no. 3
4.Lee RA, van Zundert AA, Breedveld P, Wondergem JH, Peek D, Wieringa PA. The anatomy of the thoracic spinal canal investigated with magnetic resonance imaging (MRI). Acta Anaesth Belg 2007;58:163-7.  Back to cited text no. 4
5.Imbelloni LE, Quirici MB, Ferraz-Filho JR, Cordeiro JA, Ganem EM. The anatomy of the thoracic spinal canal investigated with magnetic resonance imaging. Anesth Analg 2010;110:1494-5.  Back to cited text no. 5
6.Imbelloni LE, Pitombo PF, Ganem EM. The incidence of paresthesia and neurologic complications after lower spinal thoracic puncture with cut needle compared to pencil point needle. Study in 300 Patients. J Anesth Clinic Res 2010;1:106.  Back to cited text no. 6
7.Hopkinson JM, Samaan AK, Russel IF, Birks RJ, Patrick MR. A comparative multicentre trial of spinal needles for caesarean section. Anaesthesia 1997;52:1005-11.  Back to cited text no. 7
8.Imbelloni LE, Grigorio R, Fialho JC, Fornasari M, Pitombo PF (2011) Thoracic spinal anesthesia with low doses of local anesthetic decreases the latency time, motor block and cardiovascular changes. study in 636 Patients. J Anesthe Clinic Res S11:001. doi:10.4172/2155-6148.S11-001.  Back to cited text no. 8
9.Chambers WA, Edstrom HH, Scott DB. Effect of baricity on spinal anaesthesia with bupivacaine. Br J Anaesth 1981;53:279-82.  Back to cited text no. 9
10.Møller IW, Fernandes A, Edstrom HH. Subarachnoid anaesthesia with 0.5% bupivacaine: Effects of density. Br J Anaesth 1984;56:1191-5.  Back to cited text no. 10
11.Van Gessel EF, Forster A, Schweizer A, Gamaulin Z. Comparison of hypobaric, hyperbaric, and isobaric solutions of bupivacaine during continuous spinal anesthesia. Anesth Analg 1991;72:779-84.  Back to cited text no. 11
12.Vernhiet J, Cheruy D, Maindivide J, Vabre M, Clément C, Dartigues JF. Spinal anesthesia with bupivacaine. Comparative study of 2 hyperbaric and isobaric solutions. Ann Fr Anesth Reanim 1984;3:252-5.  Back to cited text no. 12
13.Hogan QH, Prost R, Kulier A, Taylor ML, Li S, Mark L. Magnetic resonance imaging of cerebrospinal fluid volume and the influence of body habitus and abdominal pressure. Anesthesiology 1996;84:1341-9.  Back to cited text no. 13
14.Hogan Q. Size of human lower thoracic and lumbosacral nerve roots. Anesthesiology 1996;85:37-42.  Back to cited text no. 14
15.Gouveia MA, Imbelloni LE. Understanding spinal anesthesia. Acta Anaesthesiol Scand 2006;50:259-60.  Back to cited text no. 15
16.Stevens RA, Beardsley D, White JL, Kao TC, Gantt R, Holman S. Does spinal anesthesia result in a more complete sympathetic block than that from epidural anesthesia? Anesthesiology1995;82:877-83.  Back to cited text no. 16
17.Imbelloni LE, Sant′Anna R, Fornasari M, Fialho JC. Laparoscopic cholecystectomy under spinal anesthesia: Comparative study between conventional-dose and low-dose hyperbaric bupivacaine. Local Reg Anesth 2011;4:1-6.  Back to cited text no. 17
18.Pong RP, Gmelch BS, Bernards CM. Does paresthesia during spinal needle insertion indicate intrathecal needle placement? Reg Anesth Pain Med 2009;34:29-32.  Back to cited text no. 18


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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