|Year : 2017 | Volume
| Issue : 3 | Page : 724-729
Comparison of spinal anesthesia and paravertebral block in inguinal hernia repair
Ranjana Khetarpal, Veena Chatrath, Arminder Kaur, Reeta Jassi, Renu Verma
Department of Anesthesiology and ICU, Government Medical College, Amritsar, Punjab, India
|Date of Web Publication||25-May-2017|
H. No. 111, Rajiana, Baghapurana, Moga - 142 038, Punjab
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Context: Inguinal hernia repair (IHR) is a common surgical procedure which can be performed under general, regional, or peripheral nerve block anesthesia. Aim: The aim of our study was to compare the efficacy of paravertebral block (PVB) with spinal anesthesia (SA) for IHR with respect to postoperative analgesia, ambulation, and adverse effects. Settings and Design: This was a prospective, single-blind randomized controlled trial. Materials and Methods: Sixty American Society of Anesthesiologists Class I–II patients of 20–60 years scheduled for IHR were randomized by a computer-generated list into two groups of thirty each, to receive either PVB (Group PVB: at T12–L2 levels, 10 ml of 0.5% levobupivacaine at each level) or SA (Group SA: at L3–L4/L2–L3 level, 2.5 ml of 0.5% levobupivacaine). Primary outcome was duration of postoperative analgesia and time to reach discharge criteria. Secondary outcome was time to ambulation, time to perform the block, time to surgical anesthesia, total rescue analgesic consumption, adverse effects, hemodynamic changes, patient, and surgeon satisfaction. Statistical Analysis Used: Student's t-test, Chi-square test as applicable, and Statistical Package for Social Sciences (version 14.0, SPSS Inc., Chicago, IL, USA) were used. Results: Time to the first analgesic requirement was 15.17 ± 3.35 h in Group PVB and 4.67 ± 1.03 h in Group SA (P < 0.001). Time to reach the discharge criteria was significantly shorter in Group PVB than Group SA (P < 0.001). Conclusion: PVB is advantageous in terms of prolonged postoperative analgesia and encourages early ambulation compared to SA.
Keywords: Inguinal hernia, paravertebral block, spinal anesthesia
|How to cite this article:|
Khetarpal R, Chatrath V, Kaur A, Jassi R, Verma R. Comparison of spinal anesthesia and paravertebral block in inguinal hernia repair. Anesth Essays Res 2017;11:724-9
|How to cite this URL:|
Khetarpal R, Chatrath V, Kaur A, Jassi R, Verma R. Comparison of spinal anesthesia and paravertebral block in inguinal hernia repair. Anesth Essays Res [serial online] 2017 [cited 2020 Jun 2];11:724-9. Available from: http://www.aeronline.org/text.asp?2017/11/3/724/207073
| Introduction|| |
Inguinal hernia repair (IHR) can be performed under general, regional, or local anesthesia. Spinal anesthesia (SA) is a popular technique for IHR, but it is not an ideal anesthetic technique for ambulatory surgery considering undesirable hemodynamic responses, adverse effects, and delayed discharge from the hospital., Recently, paravertebral block (PVB) has become popular for IHR, in which local anesthetic drugs are unilaterally administrated to the nerve roots and their related dermatomes without intervening central nervous system, thus avoiding the adverse effects of SA. Review of literature has revealed limited data comparing its potential as an effective anesthetic technique with SA. Hence, we decided to compare the anesthetic and postoperative analgesic efficacy of PVB technique at three levels with SA using levobupivacaine in patients undergoing IHR.
| Materials and Methods|| |
After obtaining the Institutional Ethics Committee approval and written informed consent from patients, sixty American Society of Anesthesiologists (ASA) Class I and II patients between 20 and 60 years of age group scheduled to undergo elective IHR were enrolled in this prospective, randomized controlled trial. They were divided into two groups of 30 each to receive either PVB (Group PVB) with 10 ml of 0.5% levobupivacaine at each level from T12 to L2 using nerve stimulator-guided technique or SA (Group SA) with 2.5 ml of 0.5% levobupivacaine at L3–L4/L2–L3 level. Randomization was based on a computer-generated code (by software Microsoft Excel XP ™) that was prepared at a remote site and sealed in opaque, sequentially numbered envelopes containing information regarding the assigned technique (PVB or SA). The same anesthesiologist performed the procedure of giving either block in all the patients. The other anesthesiologist did the monitoring of all the patients and had access to the patients only after sterile dressings had been applied on their back from T9 to L4 (to ensure assessor blindness) after the procedure. Due to the obvious differences in the two techniques, neither the patient nor the anesthesiologist who performed the block could have been blinded to the group assignment.
Inclusion criteria were age group of 20–60 years and ASA Class I and II. Exclusion criteria were patient refusal, coagulation disorders, any signs of sepsis, history of allergy to local anesthetic agents, body weight 20% higher than ideal body weight, significant renal, hepatic, cardiopulmonary or neurological disorders, or any anticipated difficulty in regional anesthesia.
All patients were clinically examined in the preoperative period when both techniques, their potential benefits, and side effects were explained to them. History taking, general examination, systemic examination, and assessment of the airway were carried out. Visual analog scale (VAS) of 10 cm line was also explained (0, no pain and 10, worst pain imaginable) during the preoperative visit. Routine blood investigations, a 12 lead electrocardiography, and chest X-ray were taken in all patients. Preoperative fasting of minimum 6 h was ensured in all patients.
In the operation theater, patients were connected to standard multichannel monitor (Philips IntelliVue MP50) and baseline noninvasive systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), peripheral O2 saturation, and respiratory rate were recorded. The Boyle's anesthesia machine, all emergency drugs and equipment were kept ready. Patients were cannulated with an 18-gauge or 20-gauge peripheral venous catheter and were preloaded with Ringer's lactate (10 ml/kg body weight) solution. Patients were premedicated with injection glycopyrrolate 0.2 mg intravenous (IV) and injection midazolam 2 mg IV in the operating room just before the procedure in both groups.
PVB was performed with patient in the sitting position using landmark technique and 21-gauge Locoplex needle with extension tubing (Locoplex L. 100 mm, 21-gauge Vygon, France) attached to nerve stimulator (TOF watch, Organon, Ireland). Ten milliliters of 0.5% levobupivacaine (Levo-anawin 0.5%, Neon labs, Mumbai, India) was injected at each level from T12 to L2 after fasciculation were triggered at the abdominal rectus muscle, consistent with the dermatome by 1.5 mA stimulation, and muscular response was obtained even to 0.5 mA stimulation.
SA was performed with the patient in lateral decubitus or sitting position. Under aseptic conditions, 25-gauge spinal needle (BD Spinal Needle Quincke 25-gauge × 3.5, Spain) was introduced into subarachnoid space at L3–L4/L2–L3 level using midline approach, and 2.5 ml of 0.5% levobupivacaine was injected on free flow of cerebrospinal fluid.
After block, sterile dressings were applied to the back of all patients from T9 to L4 before returning them to the supine position. O2 was given with a simple O2 mask at 5–6 L/min. Patients received intermittent injection midazolam for sedation as per requirement. Sensory block was assessed by loss of sensation to pinprick in the midclavicular line on both the sides using a 22-gauge blunt hypodermic needle every 2 min up to 10 min, at an interval of 5 min up to 30 min, every 15 min up to 120 min, half hourly up to 240 min, thereafter hourly till 12 h and 3 hourly till 24 h of surgery. Motor block was assessed at the same time intervals as sensory block using Bromage score (Grade I - free movement of legs and feet, Grade II - just able to flex knees with free movement of feet, Grade III - unable to flex knees, but with free movement of feet, and Grade IV - unable to move legs or feet).
Primary outcome, i.e., time to the first analgesic requirement was monitored using VAS. When the VAS score was >3, rescue analgesia (Injection tramadol hydrochloride, 50 mg IV, repeated if necessary) was given. The total number of rescue analgesia doses required in the 24 h was also noted. Time to reach the discharge criteria (primary outcome) was monitored as per postanesthesia discharge scoring system (PADS). The mean PADS score was evaluated every half hourly interval till 5 h and then at 6, 12, and 24 h. When the PADS score was >9, patient was considered fit for discharge and that time to reach the discharge criteria were noted.
The secondary outcome was to compare the block characteristics (time to perform the block, time to surgical anesthesia, time to ambulation, and total rescue analgesic consumption), hemodynamic changes, adverse effects, patient, and surgeon satisfaction. The time required to perform the block was taken as time from premedication (given just before block) to injection of local anesthetic drug. The block was considered as 'successful' if the onset of pinprick discrimination started within 15 min (endpoint) or if the sensory block (T10–L2) was achieved within maximum period of 30 min. Otherwise, it was considered as “block failure” and the patient was given general anesthesia and was excluded from the study. Time to surgical anesthesia was taken as time from injection of local anesthetic drug to readiness for surgery, i.e., sensory block at T10 level.
Hemodynamic parameters were recorded preoperatively, then intraoperatively every 2 min up to 10 min, every 5 min up to 30 min, every 15 min up to 120 min, half hourly up to 180 min, and at 4, 6, 12, 18, and 24 h. Hypotension (defined as SBP <20% of baseline value), bradycardia (defined as HR <60 beats/min), vomiting were treated accordingly. Any other side effects during intraoperative or postoperative period were also noted.
Patients who were unable to pass urine despite bladder fullness within six postoperative hours or complained of urinary retention were catheterized maintaining strict asepsis. The patients were observed for return of perianal sensation, the ability to dorsiflex the foot, and regaining of proprioception of the great toe. When the patient satisfied these findings, he was encouraged to ambulate under supervision provided he had clear mental status, stable hemodynamic parameters, adequate pain relief, and no residual motor block. When the patient succeeded in ambulation that time (time to ambulation) was noted. Patient satisfaction score was recorded postoperatively on a numeric rating scale from minimum 1 (very dissatisfied) to maximum 5 (very satisfied) at 24 and 48 h. After the procedure, operating surgeons were interviewed to evaluate their views regarding the procedure, and surgeon satisfaction score from 1 - poor, 2 - good, and 3 - excellent was recorded.
Sample size was calculated keeping in view at most 5% risk, with minimum 80% power and 5% significance level (significant at 95% confidence interval). Raw data were entered into a Microsoft Excel Spreadsheet and analyzed using Statistical Package for the Social Sciences (SPSS Inc., version 14, Chicago, IL, USA). Continuous data were presented as mean with standard deviation while discrete categorical data were expressed as median (range) and number of patients and/or percentage of cases. Categorical variables were analyzed using Pearson's Chi-square test and normally distributed continuous variables were analyzed using the independent sample t-test. P < 0.05 was considered statistically significant difference and P < 0.001 as highly significant.
| Results|| |
Sixty patients were enrolled in this study, and one patient in Group PVB had failed block and was given general anesthesia and was excluded from the study. Data from 59 patients were analyzed: 29 in Group PVB and 30 in Group SA. The two groups were comparable with respect to demographic data, i.e., age, weight, height, ASA class, baseline hemodynamic parameters, and duration of surgery [Table 1].
|Table 1: Comparison of demographic profile and baseline hemodynamic parameters of paravertebral block and spinal anesthesia groups|
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The mean time to the first analgesic requirement in Group PVB was significantly prolonged as compared to Group SA (P < 0.001) [Table 2]. Total analgesic consumption in first 24 h was significantly less in Group PVB (P < 0.001) [Table 2].
|Table 2: Comparison of block characteristics of paravertebral block and spinal anesthesia groups|
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Motor block was not seen in any of the patients in Group PVB, and ambulation occurred earlier in Group PVB as compared to Group SA [Table 2]. Mean PADS score was significantly higher in Group PVB [Figure 1] and time to reach discharge criteria was significantly shorter in Group PVB as compared to Group SA [Table 2].
|Figure 1: Mean postanesthesia discharge score at different time intervals|
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Time to perform the block and time to surgical anesthesia were significantly prolonged in Group PVB as compared to Group SA [Table 2].
Intraoperative vitals [Figure 2] were comparable in both the groups except for mean SBP, DBP, and HR, which were significantly reduced in Group SA (P < 0.001) after the block. No patients in Group PVB needed either ephedrine or atropine for any hemodynamic changes. However, two patients in Group SA needed ephedrine for treatment of hypotension. Bradycardia occurred in three patients in Group SA only.
|Figure 2: Comparison of intraoperative vitals in group paravertebral block and group spinal anesthesia|
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There was no incidence of urinary retention in Group PVB while five (16.7%) patients in Group SA had urinary retention (P < 0.05). In Group SA, three (10%) patients experienced nausea and vomiting and two (6.7%) patients complained of headache. The incidence of backache in Group PVB and Group SA was one (3.4%) and four (13.3%) patients, respectively, (P > 0.05) [Figure 3].
|Figure 3: Comparison of side effects in group paravertebral block and group spinal anesthesia|
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Mean patient satisfaction score was significantly higher in Group PVB as compared to Group SA at 24 and 48 h [Figure 4] in contrast to Surgeon satisfaction score which was higher in Group SA [Figure 5].
| Discussion|| |
In our study, PVB for IHR was found to be better and safer alternative to SA with the advantage of better and longer lasting postoperative analgesia, better hemodynamic stability, shorter time to reach the discharge criteria, and minimal adverse effects.
IHR is a day care surgery that demands rapid recovery and home readiness, adequate and effective postoperative analgesia, and prevention of adverse effects such as postoperative nausea and vomiting (PONV).,, The choice of anesthetic technique for IHR depends on various factors such as preference of the surgeon and anesthesiologist, the feasibility of the technique, intraoperatively and postoperative pain control, the complexity and expected duration of the procedure, postoperative morbidity, recovery time, and cost effectiveness.,, According to the epidemiological data, general anesthesia is used in 60%–70%, central neuraxial blocks in 10%–20%, and local infiltration anesthesia in 5%–10% of cases. PVB have been used with success, both as anesthetic and analgesic technique for IHR.,
In our institute, SA is a more frequently used technique of anesthesia for IHR. However, due to adverse effects such as postdural puncture headache, urinary retention, hypotension, motor block of the lower extremities, delayed mobility, and discharge from the hospital; it is not an ideal anesthetic technique for a fast track ambulatory surgery., In contrast to SA, PVB preserves lower extremity motor function, provides unilateral, segmental anesthesia of the operative side with prolonged postoperative analgesia, and reduced incidence of PONV., Review of literature has revealed limited data comparing its potential as an effective anesthetic technique with SA. For this reason, we decided to compare the anesthetic and postoperative analgesic efficacy of PVB technique at three levels with SA using levobupivacaine in patients undergoing IHR.
In our study, duration of postoperative analgesia was significantly prolonged in Group PVB compared to Group SA (15.17 ± 3.35 h vs. 4.67 ± 1.03 h) leading to early ambulation consistent with results of other studies conducted on adult as well as pediatric patients.,, Indeed, postoperative pain is one of the common reasons for delay in ambulation and discharge., In PVB, prolonged sensory block enabling prolonged analgesia is the result of comparatively less vascularity of the paravertebral space and thus slow uptake of the local anesthetics. Group PVB patients required significantly lesser number of doses of rescue analgesia (mean of 1.07 ± 0.26 vs. 2.33 ± 0.48) as compared to Group SA as longer duration of analgesia decreased the analgesic requirement. Mean PADS score were significantly higher in Group PVB as compared to Group SA. The mean time to reach the discharge criteria was significantly earlier in the Group PVB (169.66 ± 20.09 min) as compared to Group SA (264.00 ± 39.71 min) and that could be due to lesser amount of pain experienced by this group. This finding of early home readiness in our study corroborates with other studies. In our study, none of the patients of Group PVB experienced motor blockade as reported in the previous studies., Therefore, ambulation occurred much earlier in Group PVB than Group SA, in which bilateral motor blockade precludes ambulation until its anesthetic effects completely wear off.
In our study, we found that PVB caused less hemodynamic derangement in the patients as a result of unilateral nature of block and less significant sympathetic blockade. However, in the Group SA, there was a significant decrease in mean SBP and DBP compared to baseline attributable to the sympathetic block. The results of our study were consistent with those of other studies.,, The time to perform the block was significantly higher in Group PVB (15.79 ± 1.11 min) than Group SA (6.00 ± 0.74 min) because of multiple injections and nerve stimulator-guided technique in Group PVB. The time to surgical anesthesia was significantly higher in Group PVB than Group SA (16.55 ± 2.35 min vs. 8.4 ± 1.43 min) similar to other studies  owing to injections given at multiple levels.
Comparing the adverse effects in both groups, Group SA was associated with higher incidence of urinary retention (16.7%), nausea and vomiting (10%), headache (6.7%) while none of the patients in Group PVB had such complications. Urinary retention is a common side effect of the SA which might be related to hypotension that required more frequent volume expansion. Since parasympathetic fibers that innervate the autonomic bladder control were not blocked, urinary retention was not seen in Group PVB similar to other studies., SA is associated with higher incidence of PONV because of the associated sympathetic blockade leading to postural hypotension. This further precludes early ambulation in patients receiving SA while PVB provides stable perioperative hemodynamic control resulting in lower incidence of PONV. Backache occurred in four (13.3%) patients in Group SA and one (3.4%) patient in Group PVB and was manageable with rest or nonsteroidal anti-inflammatory drugs.
In our study, patients were more satisfied in Group PVB than Group SA because early ambulation was possible in Group PVB in spite of the persisting sensory block because it was segmental in nature. This persisting block offered prolonged pain relief even when the patient had started ambulating. In Group SA, the patient had pain relief only for a short period after starting ambulation, due to the nonsegmental nature of block.
More patient satisfaction seen with Group PVB corroborates with some studies,, but is in contrast to others. Since the procedure was more time-consuming and more time was needed for onset of action and thus starting the surgery, PVB was not much acceptable to the surgeons.
Some potential disadvantages of PVB include the longer time required to perform the block, need for adequate training, the possibility of block failure, and the risk of pneumothorax., Although the time to perform the block was longer than SA which is consistent with some studies, but this did not affect the time to home readiness. In our study, one patient (3%) had block failure and was excluded from the study. This is consistent with failure rates as shown in the previous studies. Multiple segments PVB are associated with increased risk of pneumothorax. Because the lung pleura extends up to T12 level, deep needle penetration during PVB above this level may result in pneumothorax., As the blocks were performed at the T12–L2 levels, pneumothorax was not observed in our study. Bilateral sensory block reflects unintentional injection into the epidural space. Epidural spread of local anesthetic was not seen in any patient of Group PVB.
Small sample size was one of the limitations of our study, so further studies should be undertaken with a larger population size. Our study was a single-blind study as double-blinding was not possible because of the obvious difference between the two techniques used. Another limitation of the study was that since we were in the initial phase of practicing the PVB technique, we used peripheral nerve stimulator-guided technique because ultrasound facilities were not available at our institute.
| Conclusion|| |
PVB can be recommended as a better and safe alternative anesthetic technique to SA for IHR as it provides unilateral AND segmental anesthesia, prolonged postoperative analgesia, early ambulation, stableintraoperative hemodynamics, and minimal adverse effects. However, the expertise required to perform, procedure-related time and prolonged onset of effect are main concerns.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]