|Year : 2015 | Volume
| Issue : 4 | Page : 121-125
Effect of different baricities of intrathecal bupivacaine on the quality of spinal block in elderly patients undergoing transurethral resection of the prostate
Magdy M Atallah, Ola T Abdel Dayem
Department of Anesthesia and Intensive Care, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt
|Date of Submission||19-Sep-2015|
|Date of Acceptance||24-Nov-2015|
|Date of Web Publication||17-Mar-2016|
Ola T Abdel Dayem
Ass. Prof Anaesthesia and Intensive Care, Mansoura University, 1 Taba St. Mansoura, Dakahlia
Source of Support: None, Conflict of Interest: None
Elderly patients undergoing spinal anesthesia require restricted block with a low dose of a local anesthetic. Considering that the baricity of local anesthetic solutions is the primary determinant of the level of motor and sensory block in nonobstetric patients, the aim of this study was to evaluate the effect of baricity of bupivacaine on the quality of spinal block and on hemodynamics in elderly patients undergoing transurethral resection of the prostate (TURP).
Materials and methods
Ninety-nine patients undergoing TURP were randomized into three groups. Patients of the first group (33 patients) received intrathecal 10 mg hyperbaric bupivacaine 0.5%. The second group of patients (34 patients) received 5 mg isobaric bupivacaine added to 5 mg hyperbaric bupivacaine, resulting in what was called 'slightly hyperbaric solution'. The third group of patients (32 patients) received 10 mg isobaric bupivacaine 0.5%. All patients were injected below L2 level in the sitting position. Sensory and motor blockade was assessed, as well as the first request for analgesic, rescue analgesics, and the overall incidence of side effects.
Onset of sensory block was comparable in the three studied groups, but motor block set earlier in the hyperbaric group and the 'slightly hyperbaric' group compared with the isobaric group. Higher sensory block was observed in the isobaric group. Recovery from sensory and motor block was earlier in the hyperbaric group. First need for analgesics was earlier in the hyperbaric group than in the 'slightly hyperbaric' and isobaric groups. Postoperative analgesia and tolerance to urinary catheter were prolonged in the isobaric and 'slightly hyperbaric' group as compared with the hyperbaric group.
Use of slightly hyperbaric bupivacaine (density = 1.013) than the traditional hyperbaric bupivacaine (density = 1.028) and the isobaric one (density = 1.007) results in good quality spinal block with fewer side effects in patients undergoing TURP.
Keywords: bupivacaine, elderly patients, intrathecal anesthesia, transurethral resection of the prostate
|How to cite this article:|
Atallah MM, Abdel Dayem OT. Effect of different baricities of intrathecal bupivacaine on the quality of spinal block in elderly patients undergoing transurethral resection of the prostate. Res Opin Anesth Intensive Care 2015;2:121-5
|How to cite this URL:|
Atallah MM, Abdel Dayem OT. Effect of different baricities of intrathecal bupivacaine on the quality of spinal block in elderly patients undergoing transurethral resection of the prostate. Res Opin Anesth Intensive Care [serial online] 2015 [cited 2017 Jun 27];2:121-5. Available from: http://www.roaic.eg.net/text.asp?2015/2/4/121/178906
| Introduction|| |
The incidence of benign prostatic hyperplasia is high (>60%) in men older than 60 years and increases up to 90% in men older than 80 years. The comorbidity rate is over 60% in elderly patients who undergo transurethral resection of the prostate (TURP), which directly affects perioperative morbidity and mortality . Spinal block is the most common anesthetic technique for TURP. It blocks up to the 10th thoracic dermatome . As regards the pain pathway and differential spinal blockade pattern, sensory block up to T12 is adequate for TURP . The sensory block levels are ~3-4 dermatomes higher in older age than in young adults . The sympathetic block level is 1-4 segments higher than the analgesia level. Therefore, in elderly patients high sympathetic block is more frequent during spinal block, which explains the incidence of cardiovascular side effects compared with young patients . There are many factors that affect intrathecal spread, including baricity, volume and concentration of injected solution, local anesthetic drug used, and position, age and weight of the patient .
Baricity was defined as the density of the local anesthetic compared with cerebrospinal fluid density. Baricity differences between spinal anesthetic solutions are thought to produce differences in the distribution of anesthetics within the subarachnoid space, which may affect the onset, extent, and duration of sensory block as well as side effects . The most significant side effect of spinal anesthesia is hypotension, which is higher in older individuals, in members of the female sex, during pregnancy, in obese individuals, and in those with diabetes mellitus, hypertension, and anemia. Other factors that increase the risk for hypotension include a block level at or above T5, use of opioids during premedication, and high local anesthetic dosage . It is commonly believed that hyperbaric solutions may be more suitable for reaching the higher thoracic dermatomes as compared with their plain equivalents .
In TURP the most important determinant is patient safety as most of the patients undergoing this surgery are elderly and they are in a fixed position throughout the procedure, making baricity almost the only factor that can determine the outcome of spinal anesthesia. Hence, the aim of this study was to compare the efficacy of different baricities of bupivacaine solution injected intrathecally in maintaining stable hemodynamics and in improving the quality of spinal block (regarding the onset of sensory and motor block, recovery of the block, and the requirement for postoperative analgesia).
| Materials and methods|| |
After getting the approval of our institutional committee, this prospective, randomized (using a random number sequence and sealed envelopes), blind study was conducted on 99 patients below the age of 80 years subjected to TURP between February 2013 and April 2014. Written informed consent was obtained from all patients. Exclusion criteria included history of back surgery, infection in the back, short stature below 150 cm, body weight more than 110 kg, coagulopathy, hypersensitivity to any of the study drugs, mental disorder, and neurological disease.
On arrival at the anesthetic room, routine monitoring in the form of ECG, noninvasive arterial blood pressure monitoring, and pulse oximetry was initiated. All patients received intravenous 150 mg ranitidine and normal saline at a rate 2 ml/kg/h preoperatively. They were randomly allocated into three groups. The first group (the hyperbaric group) included 33 patients who received 10 mg hyperbaric bupivacaine (Marcaine; Astra Zeneca) 0.5% injected intrathecally (density = 1.028). The second group (the slightly hyperbaric group) included 34 patients who received 5 mg isobaric added to 5 mg hyperbaric bupivacaine (density = 1.013). The third group (the isobaric group) included 32 patients who received 10 mg isobaric bupivacaine 0.5% (density = 1.007). Density was measured by means of a densitometer (Refractometer; Atago Co., Tokyo, Japan). Injection was below the L2 level in the sitting position using a 25-G Quincke needle. Fentanyl at a dose of 10 μg diluted in 1 ml sterile water was added to bupivacaine in all groups to reach a total volume of 3 ml. The drugs were prepared and coded by an anesthesiologist who was not involved in the study. The prepared solution was injected intrathecally by another anesthesiologist, without aspiration of cerebrospinal fluid. Three minutes after spinal injection, the patients were placed in lithotomy position with an oxygen mask (4-6 l/min). Normal saline solution was administered at a rate of 4-6 ml/kg/h. Before anesthesia, the patients were informed about the method of sensory and motor assessment. Sensory blockade was assessed using the pinprick test in the midclavicular line, and motor blockade was assessed using a four-point scale (modified Bromage scale) where 1 = complete motor block, 2 = able to move feet only, 3 = able to move feet and bend knees, and 4 = able to perform a straight leg raise . Assessment was made 3 min after intrathecal injection, and then every 2 min until the peak level was reached (the peak level was determined when the level persisted over four consecutive tests). Surgical intervention was allowed after sensory block above T10. Two expert urologists performed all operations. Maximum sensory block was measured 25 min after the block. The hemodynamics (heart rate, SpO2, and noninvasive blood pressure) were recorded 20 min before surgery, on admission to the OR, and then at 5 min intervals until the end of surgery, and every 10 min postoperatively until the end of the sensory and motor block. Recording was done by an attending anesthesiologist who was blind to the drug injected. Vasoactive drugs such as ephedrine 5 mg intravenously in increments were given on hypotension (reduction in blood pressure >25% from basal value), or intravenous atropine 0.5 mg on bradycardia (reduction in heart rate <50 beats/min). Incidence of any side effects such as nausea, vomiting, anxiety, delirium, or difficulty in breathing (discomfort) was recorded. Need for augmentation of anesthesia by intravenous increments of fentanyl 30 μg ± midazolam 1-2 mg was also recorded. Postoperative analgesia was assessed by investigators away from the study using visual analogue scale, where 0 represents absence of pain and 10 represents worst imaginable pain. Ketorolac 30 mg intravenously was given on visual analogue scale score of at least 5, and intravenous 50 μg fentanyl was added if ketorolac response was not satisfactory. Total amount of requested analgesics during the first 48 h was recorded. Data analysts and assessors of the patients were blinded to the allocation.
Statistical analysis of data was performed with SPSS for Windows version 11.5. The χ2 -test and the MannWhitney U-test were applied for continuous variables and the χ2 -test for categorical data. Hemodynamic data were compared by means of analysis of variance in repeated-measures tests. Data are expressed as mean (SD), number (%), or median (minimummaximum). A P value 0.05 or less was considered significant. A sample size of more than 28 patients per group was required to show the extent of the block (SD per dermatome) with 99% power to detect the differences and two-sided α-error of 0.05.
| Results|| |
Demographic data including age, weight, height, and duration of operation were comparable between the three studied groups [Table 1].
[Table 2] shows spinal block characters; there was no significant difference in the onset of sensory block to T8 dermatome as determined using pinprick between the studied groups. However, the onset of motor block to modified Bromage 1 (complete motor block) was faster in the hyperbaric and slightly hyperbaric groups compared with the isobaric group, without statistical significance. Recovery from sensory block was earlier in the hyperbaric group (P < 0.05) compared with the other two groups, and significantly earlier in the slightly hyperbaric group as compared with the isobaric group (93 vs. 121 min, respectively). Recovery of motor power with ability to move the leg was significantly (P < 0.05) earlier in the hyperbaric group and slightly hyperbaric group compared with the isobaric group. Data are presented in minutes as median (minimummaximum). Time to first request for analgesics was significantly earlier in the hyperbaric group compared with the slightly hyperbaric group and isobaric group. Also the number of request for intravenous analgesics during the first 48 h was higher in the hyperbaric group compared with the other two studied groups [(6 ± 3 and 5 ± 2 h), respectively] but both without statistically significant difference [Table 2].
The events associated with spinal block are shown in [Table 3], in which difficulty in breathing after 20 min of injection was comparable between the three studied groups. Bradycardia was significantly less in the hyperbaric group (18%) compared with the isobaric group (31%), whereas the slightly hyperbaric group was between the other two groups (20%). Hypotension and the consequent nausea and vomiting were more significant in the hyperbaric group (33% for hypotension and 12% for nausea and vomiting) compared with the medium baric group and isobaric group. The number of patients who needed augmentation for analgesia was higher in the hyperbaric group (six patients) than in the slightly hyperbaric group (three patients) and isobaric group (one patient), with no statistical significance.
[Figure 1] shows the maximum sensory block level measured after 25 min following spinal block. The maximum sensory block (T4) was higher in the isobaric group (12 patients) compared with the hyperbaric group (nine patients) and slightly hyperbaric group (11 patients). Meanwhile, the lowest sensory block level (T8) was significantly more in the hyperbaric group (10 patients) compared with the isobaric (two patients) and slightly hyperbaric (six patients) groups.
| Discussion|| |
TURP is among the one-day surgeries that have increased in frequency. The demand for anesthetic techniques that can provide fast recovery and stable hemodynamics for these surgeries has also increased . Baricity difference between spinal anesthetics within the subarachnoid space may affect the onset, extent, and duration of sensory block as well as side effects. It is commonly believed that hyperbaric solution may be more suitable for reaching a higher level as opposed to the plain equivalents , and it is more popular in practice than equal doses of plain bupivacaine . In this study we compared equal doses of hyperbaric (density = 1.028), isobaric (density = 1.007), or slightly hyperbaric bupivacaine (density = 1.013) for spinal anesthesia in TURP. It was found that hyperbaric and slightly hyperbaric bupivacaine have more rapid onset of sensory and motor block (6 min for sensory block, 3-4 min for motor block). This was in accordance with the observation of Sia et al. , who suggested that intrathecal hyperbaric bupivacaine had more rapid onset of sensory blockade than isobaric bupivacaine. In contrast, Loubert et al.  assessed the effect of gravity on the spread of local anesthetic solution of different baricities in obstetric patients and concluded that hypobaric bupivacaine resulted in higher sensory block and a higher rate of successful sensory block than isobaric or hyperbaric bupivacaine. This controversy could be explained by the fact that the position of patients in TURP is totally different from the position of obstetric patients. The interaction between patients' position and local anesthetic baricity at the time of spinal injection was assessed by Hallworth et al. . The authors demonstrated that when pregnant women are sitting during spinal injection the spread of the local anesthetic solutions tends to follow gravity, and thus they did not observe a difference in sensory block level between hyperbaric and hypobaric solutions when the patients were lying in the lateral position. Further, although the baricity of the local anesthetic solution is the primary determinant in nonobstetric patients, this is not the case in obstetric patients near their term . The recovery of sensory block was significantly longer in the isobaric group compared with the hyperbaric group, whereas the slightly hyperbaric group was midway between the other two groups. The need for rescue analgesics in the first 48 h was significantly higher in the hyperbaric group compared with the other two studied groups. As regards side effects, hypotension and consequently nausea and vomiting were markedly increased in the hyperbaric group compared with the slightly hyperbaric and isobaric bupivacaine groups. Decrease in venous return and systemic vascular resistance caused by sympathetic nervous system block are the primary causes of spinal anesthesia-induced hypotension . An earlier study  stated that both hyperbaric and plain solutions of bupivacaine with fentanyl provided satisfactory surgical anesthesia and postoperative analgesia, although motor block was slightly prolonged in the plain group but of little consequence, and the risk for hypotension was marginally higher in the hyperbaric group. In contrast to our results, Toptass et al.  found no difference between hyperbaric and isobaric bupivacaine regarding the frequency of hypotension and bradycardia. This could be explained by the fact that patients in the Toptass trial were positioned in 30° sitting position after intrathecal injection. This position is not feasible in TURP patients, who should be laid in lithotomy position.
| Conclusion|| |
Many factors influence the spread of intrathecal local anesthetic. Among them baricity and position are the most important. Use of slightly hyperbaric bupivacaine (density = 1.013) compared with the traditional hyperbaric bupivacaine (density = 1.028) and the isobaric one (density = 1.007) reduced the risk of excessive spread but still ensured good quality of the block with fewer side effects in patients undergoing TURP.
| Acknowledgements|| |
Conflicts of interest
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[Table 1], [Table 2], [Table 3]