This was a prospective randomized comparative study in which data was collected from July 2013 to July 2014 after IRB II permission. Sample size was calculated on the basis of a pilot study to compare efficacy of epidural block with spinal anaesthesia in which 20 patients were randomly selected and divided into two groups. Mean difference between findings of two groups was 0.55; power of study was 80 with allowable error 5%. Pilot study was analysed and sample size of 40 was calculated in each group using ‘openepi’. Patients included in the study who had stone in the pelvi-calyceal system, between age group 18-60 years and with ASA grade I or II. Written informed consent is taken. Exclusion Criteria were history of cardiac, respiratory, neuromuscular, hepatic or major renal disease, systemic illness that may result in hypotension during anaesthesia e.g. haemodynamically significant aortic or mitral valve stenosis, allergy to local anaesthetics, patient refusal, and pregnancy or skin infection of the back. Patients were randomly allocated into 2 groups using table of randomization (n= 40 each) Group E- Epidural block, Group S- Spinal block. For Group E- patients, 3ml of 2% lignocaine was infiltrated in skin & subcutaneous tissue. Tuohy’s needle was inserted by Para median approach & epidural space confirmed with loss of resistance to air technique. Epidural catheter inserted 4cm inside the T10-T11 space and fixed. Test dose was given with 3 cc of 2% lignocaine and further dose was given accordingly to achieve sensory level of T-6. After achieving adequate sensory level, patient was positioned prone and epidural infusion with 0.25% bupivacaine was started at the rate of 5ml/hr. Time taken to achieve T6 level and dose of bupivacaine was noted and infusion was continued till the end of the surgery. After the surgery epidural buprenorphine 60-90mcg was given 12 hourly for Postoperative analgesia. On day two epidural catheters was removed after giving epidural top.

For Group S patients, 2ml of 2 % lignocaine was infiltrated in skin and subcutaneous tissue. Quincke’s needle was inserted. Spinal block was given with 3.5ml of 0.5% Bupivacaine and 60mcg Norphine in the L3-L4 space. After achieving adequate sensory level, patient was positioned in prone position. All patients from both the groups were transferred to ward where they were monitored. The Postoperative pain was assessed using VAS (Visual Analog Scale) - score where ‘0’ score corresponds to no pain and ‘10’ to maximum or worst pain. Patients were given IV tramadol for pain relief in the Postoperative period every eight hourly in spinal group and when required in epidural group. Parameters evaluated in study groups E (Epidural) & S (Spinal) were patient characteristic and operative details, intra-op mean arterial blood pressure, intraoperative heart rate, time taken for surgery, intraoperative blood loss, the severity of postoperative pain for 24 hours using VAS score, Number of patients requiring postoperative analgesia, Intensity motor blockade using Bromage scale, incidence of side effects like nausea, vomiting, urinary retention and any other adverse events were noted. Patient satisfaction for pain relief and intraoperative patient comfort for prone position was asked in postoperative period on Visual Analogue Scale parameter [3].

Data was presented as mean (SD). Complete failure and unsatisfactory block (where even after giving block patient still had sensations of touch) were grouped together as failure and excluded from the study. Results of the study were observed and analysed statistically. Quantitative data was analysed using unpaired t-test and qualitative data was analysed using chi-square test. Statistical difference was considered significant if p< 0.05.

[Table/Fig-1] shows that patients in both the groups were comparable with respect to age, gender, ASA grade.

[Table/Fig-2] shows that patients in both the groups were comparable with respect to stone size, puncture site and duration of surgery.

[Table/Fig-3] shows that number of attempts were significantly higher in epidural group as compared to spinal group (p=0.04411). Mean time (min) required to achieve the level in group E and group S was 15.45±2.8 and 8.52±2.62 min respectively and difference was highly significant (p<0.0000001).

[Table/Fig-4] shows, baseline MAP was comparable in both the groups and difference was not significant (p= 0.1065). MAP at 5min (p=0.001372), 10min (p=0.000008587), 15min (p=0.0006086) were significantly lower in spinal group as compared to epidural group. After 30 minutes, differences were not significant but still MAP was lower in spinal group. After 1 hour 30 minutes, MAP was low in epidural group as compared to spinal group but differences were not significant. At 2 hours and 15 minutes MAP was lower in group E and difference was significant (p=0.006716).

[Table/Fig-5] shows that baseline Heart Rate (beats/min) was comparable in both the groups with insignificant difference (p=0.2390). But, after 30 minutes difference in heart rate between two groups was statistically significant and higher rate recorded in spinal group till the end of 3hours.

[Table/Fig-6] shows that Postoperative VAS score was significantly higher in spinal group and 4 hours onwards difference was highly significant.

[Table/Fig-7] shows that PONV Score was significantly higher in spinal group as compared to epidural group.

[Table/Fig-8] shows that patient satisfaction was greater in epidural group as compared to spinal group

In present study, we have compared the safety and efficacy of segmental epidural block versus spinal anaesthesia for PCNL. Epidural block was associated with more intraoperative haemodynamic stability, reduced Postoperative pain and lower Postoperative analgesic requirements for 24 hours than the spinal group. Number of attempts required for epidural placement of needle was higher as compared to spinal block which suggest that epidural block is technically more difficult than spinal block. Also time required to achieve the desired level is more in epidural group than the spinal group.

In a prospective randomized study comparing spinal epidural block vs. general anaesthesia Singh V et al., [4] reported lower VAS score, less need for analgesics and shorter hospital stay in spinal epidural group. Kuzgunbay et al., [2] compared general anaesthesia with spinal epidural anaesthesia with respect to operative time, Postoperative haemoglobin level, hospital stay, success rate and Postoperative complications and found no difference between two besides patient’s satisfaction which was reported more with spinal epidural block [5,6]. General Anaesthesia prone to complicate in terms of vascular, pulmonary and neurological issues, especially during changing patient’s position from lithotomy to prone [7]. Spinal Anaesthesia is usually associated with hypotension during changing into prone position [8,9].

Mehrabi et al., evaluated 160 patients who were submitted to PCNL in the prone position under spinal anaesthesia [7]. Six patients developed mild to moderate headache, dizziness and low back pain. Ten patients (6.3%) received blood transfusion. Among these patients, 18 patients had hypotension controlled by intravenous ephedrine. They concluded that PCNL under spinal anaesthesia is an alternative technique to GA. In contrast, several reports failed to found haemodynamic instability during changing the patient position from supine to prone [10].

In present study, intraoperative MAP was significantly lower in spinal group as compared to epidural group and was statistically highly significant. Also, heart rate was more in spinal group throughout the procedure suggesting that haemodynamic stability is better in epidural group. Postoperative VAS score was significantly higher in spinal group and 4hours onwards difference was highly significant. Less PONV score was noted in epidural group as compared to spinal group. Higher incidence of Postoperative nausea and vomiting in spinal group may be due to use of Tramadol (synthetic opoid) as analgesic. Greater patient satisfaction was noted in epidural group than spinal. This may be attributed to better Postoperative analgesia and mobility in Postoperative period and less PONV. One more advantage of epidural block is that patient can himself take prone position without much assistance. So, less Operative Theatre assistants were required for positioning of patients in epidural group.

Present study shows that segmental epidural anaesthesia is also a good alternative for PCNL. Epidural anaesthesia has the advantage of patient self-positioning for surgery, option of prolongation of anaesthesia time available, safer in high risk cardiac patients. But, our study was limited by the fact that only ASA grade 1 and 2 patients were included and patients with creatinine >3.5 mg % and serious co-morbidities were excluded. Also, number of patients was less.

From present study, it was concluded that for PCNL, segmental epidural block is better than spinal anaesthesia in terms of better haemodynamic stability, Postoperative analgesia, patient satisfaction, reduced incidence of PONV. Though both types of regional anaesthesia are safe and effective, epidural anaesthesia is difficult to execute and takes longer time to act as compared to spinal block; which limits its use.