Paravertebral block is a proper alternative anesthesia for outpatient lithotripsy.

CONTEXT: This study evaluated the effectiveness of paravertebral block as an alternative anesthetic technique for extracorporeal shock wave lithotripsy (ESWL) procedure. A total of 50 patients with renal stones, aged 20-60 years, were randomly allocated into two groups; 25 patients in group P; received unilateral paravertebral block from T8 through L1 with injection of 5 mL 0.5% bupivacaine and 25 patients in group L; received local infiltration by bupivacaine 0.25% (2 mg/kg) into the 30 cm(2) area after localizing the stones site, 10 min before the session. A total of 10 mm visual analogue scale (VAS) was used to evaluate pain every 10 min during the session. At the end of the procedure, total doses of rescue analgesia, the number of shockwaves, their power, and the total duration of shockwave treatment were recorded. After completion of the procedure, the patient was assessed for pain and nausea in the postanesthesia care unit (PACU) using the VAS. Patient's satisfaction and time needed to discharge patients to home also were recorded. Time to do the anesthetic technique was significantly higher (P < 0.001) in group-P than group-L, it was 12.7 ± 2.3 min versus 6.9 ± 1.9 min, respectively; intraoperative rescue analgesia by fentanyl was lesser (P < 0.001) in group-P than group-L, 26.7 ± 6.32 mcg versus 78.6 ± 5.41 mcg, respectively, also time interval between ends of the procedure till discharge to home was significantly higher (P < 0.001) in group-P than group-L, it was 99 ± 17 min versus 133 ± 31 min, respectively. VAS was not significant difference between both groups either intraoperative or postoperative in first hour. Patient's satisfaction was significantly higher (P < 0.05) in group-P than group-L, it was 8.8 ± 1.1 versus 6.1 ± 0.6, respectively. Adverse events were lesser, but not significant in group-P than in group-L. Two patients (8%) in group-L and one patient (4%) in the group-P experienced episodes of postoperative nausea and vomiting (PONV). Paravertebral block is an effective alternative anesthesia for outpatient lithotripsy; multiple level paravertebral blocks provide an optimal anesthetic condition, with acceptable adverse events for ESWL. And, providing proper analgesia during the procedure and in first hour after finishing of the procedure, early discharge to home and providing better patient's satisfactions. AIMS: This study evaluated the effectiveness of paravertebral block as an alternative anesthetic technique for ESWL procedure. SETTINGS AND
DESIGN: Prospective open label study. SUBJECT AND METHODS: A total of 50 patients with renal stones, aged 20-60 years, were randomly allocated into two groups; 25 patients in group P; received unilateral paravertebral block from T8 through L1 with injection of 5mL 0.5% bupivacaine and 25 patients in group L; received local infiltration by bupivacaine 0.25% (2 mg/kg) into the 30 cm(2) area after localizing the stones site, 10 min before the session. A total of 10 mm VAS was used to evaluate pain every 10 min during the session. At the end of the procedure, total doses of rescue analgesia, the number of shockwaves, their power, and the total duration of shockwave treatment were recorded. After completion of the procedure, the patient was assessed for pain and nausea in the PACU using the VAS. Patient's satisfaction and time needed to discharge patients to home also were recorded. STATISTICAL ANALYSIS: The findings of the two groups were statistically compared using SPSS version 12 (SPSS Inc., Chicago, IL). Data were expressed as mean ± standard deviation, number, and percentage. Nominal nonparametric data were analyzed using Chi-square test. Parametric data were compared using unpaired t-test. Ordinal nonparametric data were analyzed using Mann-Whitney U-test.
RESULTS: Time to do the anesthetic technique was significantly higher (P < 0.001) in group-P than group-L, it was 12.7 ± 2.3 min versus 6.9 ± 1.9 min, respectively; intraoperative rescue analgesia by fentanyl was lesser (P < 0.001) in group-P than group-L, 26.7 ± 6.32 mcg versus 78.6 ± 5.41 mcg, respectively, also time interval between ends of the procedure till discharge to home was significantly higher (P < 0.001) in group-P than group-L, it was 99 ± 17 min versus 133 ± 31 min, respectively. VAS was not significant difference between both groups either intraoperative or postoperative in first hour. Patient's satisfaction was significantly higher (P < 0.05) in group-P than group-L, it was 8.8 ± 1.1 versus 6.1 ± 0.6, respectively. Adverse events were lesser, but not significant in group-P than in group-L. Two patients (8%) in group-L and one patient (4%) in the group-P experienced episodes of PONV.
CONCLUSIONS: Paravertebral block is an effective alternative anesthesia for outpatient lithotripsy; multiple level paravertebral blocks provide an optimal anesthetic condition, with acceptable adverse events for ESWL. And providing proper analgesia during the procedure and in first hour after finishing of the procedure, early discharge to home and providing better patient's satisfactions.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Many anesthetic regimens have been successfully used for extracorporeal shock wave lithotripsy (ESWL): General anesthesia,[1] epidural anesthesia,[23] spinal anesthesia,[45] flank infiltration with or without intercostal nerve blocks,[67] and analgesia sedation.[89]

Peripheral nerve block offers a significant recovery advantage for the ambulatory surgery patient as a result of its superior analgesia and low incidence of opioid-induced side effects.[1011] Paravertebral nerve block (PVB) is a regional technique that has been successfully used for a variety of surgical procedures, including breast surgery, thoracotomy, cholecystectomy, nephrectomy, and inguinal herniorraphy.[121314151617] PVB offers specific, nonopioid analgesia in a dermatomal distribution. Although PVB has not been studied previously for outpatient urologic surgery, only single case report is available.[18] We assume that paravertebral block will provide a proper analgesia during and after ESWL. ESWL represents first-line therapy for the majority of urinary tract calculi. Renal and ureteral calculi are crushed into small fragments by shock waves and then pass spontaneously as small fragments. ESWL is a noninvasive procedure and requires anesthesia less than other treatment modalities. Majority of patients undergoing lithotripsy are outpatients and discharged on the same day of procedure.[19] During the procedure patients experience sharp, stinging pain produced by the impact of the shock waves at the cutaneous entry site. Due to this sharp pain, patient may move leading to the need of repeated radiographic localization of the stone(s) for an effective lithotripsy. Effective ESWL requires a cooperative patient who should remain immobile on the lithotripsy table till the end of procedure.[7]

SUBJECTS AND METHODS

After obtaining the institutional ethics committee's approval, 50 patients of ASA physical status I and II; aged 20-60 years, with radiopaque, single kidney stones smaller than 20 mm, detected by X-ray of the kidneys, ureters, and bladder, abdominal ultrasonography, and intravenous (I.V.) urography; were included in this study. The stone size was determined according to the maximal stone diameter, scheduled to undergo elective ESWL. The exclusion criteria were Patients’ refusal, obesity with body mass index >30 kg/m2, coagulopathy and significant cardiovascular, respiratory, renal, hepatic, or metabolic disease. Patients with a history of substance abuse, psychiatric problem, and who were unable to cooperate with the investigation, active gastrointestinal reflux, chronic analgesic use, and allergy to local anesthetics were also excluded.

After application of standard monitoring including electrocardiograph, noninvasive blood pressure, and pulse oximetry, an I.V. ringer lactate infusion (10 mL/kg/h) was started. Patients were given oxygen by facemask and premedicated by 1 mg midazolam and 50 mcg fentanyl to decrease anxiety and discomfort during the procedure. Before premedication, each patient was instructed on the use of standard 10 mm visual analogue scale (VAS) with 0 = no pain and 10 = worst pain before the procedure to enable understanding and cooperation of this investigation during and after the procedure. The procedure was well-explained to all the patients, and they were advised not to move during the procedure, they were instructed to ask for analgesic drugs for intolerable pain or discomfort.

Patients were randomized, following a sealed envelope method, to receive either a unilateral paravertebral block (group-P, no = 25) or local anesthetic infiltration (group-L, no = 25). Intra-and postoperative data were recorded by physician not participating in the study.

In group P, The unilateral PVB was performed in a sitting position. (T8 through L1) with the patient in the sitting position. The needle entry sites were marked 2.5 cm lateral to each spinous process, the skin was cleansed with chlorhexidine, and the injection sites were infiltrated with 1% lidocaine. At each level, a 22-gauge, 50-mm insulated stimulating needle (Stimuplex; B Braun Medical, Inc, Bethlehem, PA) connected to a nerve stimulator (initial current 2 mA, 0.1 ms, 2 Hz) was advanced anteriorly into the parasagittal plane until it contacted the transverse process. The needle was then withdrawn and redirected caudally approximately 0.5 cm past the transverse process until an intercostal motor response was elicited or a subjective sensation of muscle contraction was reported. The stimulating current was reduced to below 0.8 mA; then 5 mL of 0.5% bupivacaine was injected at each level.

Before surgery, the patient had decreased sensation to pinprick in the appropriate dermatomal levels unilaterally.

In group L, the patients received a local infiltration by bupivacaine 0.25% with maximum dose (2 mg/kg) into the 30 cm2 area in diameter, around the posterior axillary line, beginning just above the last rib downward and including intradermal, subcutaneous, muscular and periosteal infiltration, which was performed with a single needle entry, after localizing the stones site and size. ESWL was started 10 min after the infiltration after examine sensation in that area by pinprick. Shockwave lithotripsy was performed by ESWL machine (BMA-MOBITRIP-MT-1RX), with ellipsoid reflector with shockwave coupling of water cushion (electrohydraulic lithotripsy) with C-arm (Philips BV25). Patients who had pain during the procedure with VAS >3 received 0.25 mcg/kg I.V. fentanyl as a rescue analgesia, which was repeated on demand and was recorded.

The visual analog scale (VAS) was assessed every 10 min till the end of ESWL, then every 15 min in the postanesthesia care unit (PACU).

All patients were asked to report and were interrogated continuously for early symptoms of local anesthetic toxicity including light-headedness, lip or tongue numbness, drowsiness, fatigue, nausea, and dizziness.[2021]

At the end of the procedure, the number of shockwaves, their power, and the total duration of shockwave treatment were recorded. After completion of the procedure, the patients were discharged with routine therapy and instructions if they fulfilled our local discharge criteria which mandate that the patient is fully conscious; he can walk to the bathroom and void, has no nausea or vomiting, and is hemodynamically stable.

Postoperatively, the patient was assessed for pain and nausea in the PACU using the VAS. Ondansetron (4 mg) I.V. was used as the rescue antiemetic. If patient required no opioids or antiemetics for 1 h, then he will be discharged to home and time interval between end of the procedure till discharge to home will be recorded. Patient's satisfaction with their anesthetic technique was assessed using a 10-point VAS, with 0 = highly dissatisfied to 10 = completely satisfied at first hours postoperatively.

Statistical analysis

The findings of the two groups were statistically compared using SPSS version 12 (SPSS Inc., Chicago, IL). Data were expressed as mean ± standard deviation, number and percentage. Nominal nonparametric data were analyzed using Chi-square test. Parametric data were compared using unpaired t-test. Ordinal nonparametric data were analyzed using Mann-Whitney U-test. P< 0.05 were considered statistically significant.

RESULTS

No statistical difference between the two groups as regard demographic characteristics (age, weight, height, ASA class) and preoperative vital data (HR, MAP, SpO2) [Table 1]. The performance time of the anesthetic technique was significantly higher (P < 0.001) in group-P than in group-L, it was 12.7 ± 2.3 min versus 6.9 ± 1.9 min, respectively. Intraoperative rescue analgesia by fentanyl was significantly lesser (P < 0.001) in group-P than in group-L, it was 26.7 ± 6.32 mcg versus 78.6 ± 5.41 mcg, respectively. Also the PACU stay time, which is the time interval between ends of the procedure till discharge to home, was significantly lesser (P < 0.001) in group-P than in group-L, it was 99 ± 17 min versus 133 ± 31 min, respectively. The intraoperative vital signs, stone size, numbers of shocks, voltage, and ESWL duration showed no statistical difference between the two groups [Table 2].

Table 1

Demographic data and preoperative vital data

Table 2

Time of anesthetic technique, intraoperative, and postoperative data

VAS was not significantly different between both groups either intraoperative or postoperative [Figure 1, Table 3], respectively.

Figure 1

Intraoperative visual analog scale between the two groups, VAS = Visual analogue scale

Table 3

VAS at different times in PACU

Patient's satisfaction was significantly higher (P < 0.05) in group-P than in group-L, it was 8.8 ± 1.1 versus 6.1 ± 0.6, respectively [Figure 2].

Figure 2

Patient's satisfaction between the two groups. *=Significant difference (P<0.05) between the two groups

Adverse events were lesser, but not significant in group-P than in group-L. Two patients (8%) in group-L and one patient (4%) in the group-P experienced episodes of postoperative nausea and vomiting and were treated with I.V. ondansetron (4 mg).

DISCUSSION

In our study, six-segment PVB for ESWL was found to be a viable alternative to other anesthetic techniques like local anesthetic infiltration in achieving significant lower doses of rescue analgesia with P< 0.001 and significant more patients satisfaction P< 0.05 with shorter time to discharge from hospital with P< 0.001 without significant side effects.

Although multiple-segment PVB injections provided very good anesthetic condition in a short time, they were not comfortable for patients and also increased the chances of pleural puncture and pneumothorax,[222324] and to avoid that complication we used nerve stimulator guidance to aid the practitioner in placing the needle tip in the appropriate position.[1625]

Perioperative multiple-injection paravertebral blocks was confirmed as a proper anesthetic and analgesic in many studies like Kaya et al.,[26] were studied 50 patients underwent video-assisted thoracic surgery and concluded that perioperative multiple-injection thoracic paravertebral blocks with bupivacaine containing epinephrine provided effective pain relief and a significant reduction in opioid requirements which is correlated with our study.

Mandal et al.,[27] were compared paravertebral block versus unilateral spinal anesthesia for inguinal hernia repair, 52 patients were enrolled in their study divided in two groups and in paravertebral group was using two-segment paravertebral block at T10 and L1 and they were concluded that two-segment, paravertebral block provides an optimal anesthetic condition for unilateral inguinal hernia repair. Paravertebral block is advantageous in providing segmental anesthesia, early ambulation, and prolonged pain relief. In the hands of experts, paravertebral block can be a safe alternative to unilateral spinal anesthesia for unilateral inguinal hernia repair.

Elganainy et al.,[7] studied the efficacy and safety of local infiltration of lidocaine 1% as a monotherapy in ESWL and their study contained 100 patients with renal stones, which were randomly allocated into two groups to either received intramuscular injection of 20 mg ketorolac or to received lidocaine 1% by local infiltration and their conclusion was lidocaine 1% by local infiltration is considered an effective and inexpensive agent that can be applied with minimal morbidity during renal ESWL, but it could not be used as a monotherapy but it effectively reduced the need for analgesia. Which also correlated to our results, as local infiltration group were in significant higher in need for more rescue analgesia.

Intrathecal anesthesia for ESWL was studied before by Lau et al.,[5] who was comparing intrathecal sufentanil with intrathecal lidocaine and patients were assessed for intraoperative and postoperative pain and recovery profile and their conclusion was intrathecal sufentanil safe and effective alternative drug for ESWL.

Comparing general anesthesia versus epidural anesthesia studied by Richardson and his colleagues at 1998,[28] and their conclusion suggests that opioid-free general anesthesia using propofol, nitric oxide, and laryngeal mask airway is effective and is associated with rapid recovery and minimal side effects. General anesthesia obviates concerns regarding neuraxial anesthetic-associated postdural puncture headache, transient neurologic symptoms, urinary retention, and pruritus. In our study with multiple level paravertebral blocks none of the previous neuroaxial complications happen due to different technique and no opioid was injected into paravertebral space.

To our knowledge, this the first study which studies the efficacy of paravertebral block as effective anesthetic technique for patients undergoing for ESWL procedure, only one case report by Jamieson and Mariano[18] has reported that left PVB (T8 through L1) for patient with upper pole renal calculus with sedation by low-dose propofol infusion 25-50 mcg/kg/min without opioids and find that patient not complaining from any episodes of pain or nausea, and she was discharged from PACU to home after 72 min, and patient reported no pain despite passing multiple small stones overnight for the first 24 h. In contrast, in our study patient was satisfied by paravertebral technique as sole anesthetic technique during ESWL without using sedation.

CONCLUSION

Paravertebral block is an effective alternative anesthesia for outpatient lithotripsy; multiple level paravertebral blocks provide an optimal anesthetic condition, with acceptable adverse events for ESWL. PVB is advantageous in providing proper analgesia during the procedure and in first hour after finishing of the procedure, early discharge to home and providing better patient's satisfactions.

The limitations of this study were the relatively small number of patients included, we did not follow-up patients for the first 24 h at least. The strengths of this study are the first study that confirms multiple level unilateral paravertebral block is effective as a single anesthetic technique for ESWL procedure without clinically significant side effects; in addition to better patient satisfaction. Further studies are needed with prolonged patients’ follow-up and on larger numbers of patients.