Tubeless versus common minimally invasive percutaneous nephrolithotomy for renal stones under local anesthesia: analysis of clinical outcomes

Background: To compare the clinical outcomes of tubeless minimally invasive percutaneous nephrolithotomy (cid:0) mPCNL (cid:0) and common minimally invasive percutaneous nephrolithotomy under local anesthesia, and to explore the feasibility, safety and clinical ecacy of tubeless mPCNL under local anesthesia. Methods: Patients with PCNL who underwent local anesthesia from January 1, 2018 to November 30, 2018. The patients were divided into Group 1 (tubeless mPCNL: indwelling double J tube, no indwelling nephrostomy tube) and group 2 (common mPCNL: indwelling double J tube and nephrostomy tube). The intraoperative and postoperative parameters of the two groups were compared, including operation time, average postoperative hospital stay, puncture position, postoperative hemoglobin decline, postoperative visual analogue scale (VAS), analgesic use, postoperative fever and stone removal rate. Results: In group1,the VAS scores of 6 hours after surgery was 4.07±1.79 signicantly lower than that for group 2 (4.07±1.79 vs 6.24±1.33, P<0.05). and There was a statistically signicant difference in the use of analgesics between the two groups (cid:0) P<0.05 (cid:0) . The VAS scores of day 1 after surgery (2.50±1.76 vs 3.83±2.22 in group1 and group2) was signicantly lower in the tubeless mPCNL (P<0.05). The hospital stay for group 1 was signicantly shorter than group 2(3.15±1.42 vs 6.48±1.88 days, P<0.01)). There were no signicant differences in the operation time, puncture position, postoperative hemoglobin decline rate, VAS score on the day of discharge, postoperative fever, and stone removal rate between the two groups (P>0.05). Conclusion: Tubeless mPCNL is a simple, safe and effective technique under local anesthesia. It is worthy of clinical

group 2 (4.07±1.79 vs 6.24±1.33, P<0.05). and There was a statistically signi cant difference in the use of analgesics between the two groups P<0.05 . The VAS scores of day 1 after surgery (2.50±1.76 vs 3.83±2.22 in group1 and group2) was signi cantly lower in the tubeless mPCNL (P<0.05). The hospital stay for group 1 was signi cantly shorter than group 2(3.15±1.42 vs 6.48±1.88 days, P<0.01)). There were no signi cant differences in the operation time, puncture position, postoperative hemoglobin decline rate, VAS score on the day of discharge, postoperative fever, and stone removal rate between the two groups (P>0.05). Conclusion: Tubeless mPCNL is a simple, safe and effective technique under local anesthesia. It is worthy of clinical application. Tubeless mPCNL treatment for renal stones can signi cantly reduce postoperative pain and shorten hospital stays compared with common m PCNL. Background PCNL has now become one of the preferred treatments for renal stones and some of the upper ureteral calculi. The EAU Guidelines recommend PCNL as a rst-line treatment for renal stones larger than 20mm [1] . However, the drainage method after PCNL is still being improved and improved continuously [2] .
The traditional drainage method after PCNL is indwelling renal stula and ureteral stent. In recent years, tubeless PCNL (that is, only the ureteral stent tube is not placed after the operation) has attracted more and more people's attention. It has been published that tubeless PCNL can signi cantly reduce patient's postoperative pain and discomfort [3,4] . Besides, tubeless PCNL has the potential advantage of shorter hospital stay [3,4] . However, the surgical inclusion criteria are so strict that this method has not been widely accepted and popularized. for PCNL can be performed under both general anesthesia and local anesthesia. Recently, studies have reported that PCNL is superior in local anesthesia than in general anesthesia including lower dose requirements for analgesics [5,6] . In this study, the feasibility, e cacy and safety of tubeless PCNL under local anesthesia were studied by retrospective trials, providing further evidence-based medical evidence for the development of tubeless PCNL.

Patients selection
Between January 1, 2018 andNovember 30, 2018, 135 patients undergoing PCNL were incorporated into this retrospective study at our center, including 68 patients underwent tubeless PCNL (group 1, including 46 males and 22 females) and 67 patients common mPCNL (group 2, including 41 males and 26 females). The inclusion criteria were intravenous urography (IVU) or CT diagnosis of non-complex kidney stones. The stones diameter was 20 ~ 40 mm. The exclusion criteria were multi-channel PCNL, intraoperative aspiration system perforation, severe bleeding, urinary tract infection, renal empyema, renal stones with renal cortical thickness < 5 mm, residual stones requiring secondary PCNL, ureteral stricture or renal pelvis, stenosis of the ureteral junction, previous history of renal surgery, cardiopulmonary and pulmonary infections, mental disorders, coagulopathy, anesthesia allergy, spinal deformity. This study has been approved by the A liated ZhuZhou Hospital XiangYa Medical College CSU, a ethics number (NO:2017-08116). All participating patients have signed surgical consent, anesthesia informed consent and clinical research consent. This study was conducted in accordance with the Declaration of Helsinki and good clinical practice according to the International Conference on Harmonization guidelines.

Surgery methods
Intramuscular injection of meperidine hydrochloride 75 mg and promethazine hydrochloride 25 mg was given 30 min before surgery. 10 ml of 1% lidocaine hydrochloride was pushed through the urethra with a syringe at lithotomy position. After 5 minutes, the 5F ureteral catheter was retrogradely inserted from the ureter to the renal pelvis under the ureteroscope. The ureteral catheter was connected with saline to establish arti cial hydronephrosis, and the catheter was indwelled and xed. With the patient in a prone position, the point and direction of puncture under the 11th intercostal space or the 12th rib were determined under ultrasonic positioning. Local anesthesia was performed with 10 ~ 40 ml of 1% lidocaine hydrochloride. For the estimated longer operation time, 0.1 ml of epinephrine was added per 10 ml of 1% lidocaine hydrochloride, and the amount of an aesthetic was not more than 40 ml. After successful anesthesia, under the guidance of B-ultrasound, the correct position of 18G puncture needle was con rmed, Ultrasonography-guided percutaneous punctures with an 18G puncture needle were made into the designed calix. After the urine e ux was seen, a guidewire (PTFE-coated guidewire; Coloplast, Humlebaek, Denmark) was inserted into the collecting system. A 1-cm skin incision was made, use dilation stepwise system to expand to 18F in turn, and a 18F working sheath was placed directly as the percutaneous tract. Under direct nephroscope (8.5/11.5F) (Karl Storz GmbH Co.KG,Tuttlingen Germany)vision, the stone was fragmented by holmium laser. The stone fragments were pushed out by an endoscopic pulsed perfusion pump or taken out by lithotomy forceps. A kidney ultrasound and X-ray was performed a second time to con rm the clearance of the stone before the end of the operation. Finally, a 5F double-J stent was inserted in the ureter, and a nephrostomy tube (18F) was placed in all patients of group 2.

Patients records
The patient's age, gender, height, weight, stone size, operation time, the average postoperative hospital stay, puncture location, postoperative hemoglobin decline, postoperative visual analogue scale (VAS), postoperative fever, and stone removal rate were observed in this study. A comparative study was performed on the parameters of the two groups of patients.

Statistical analysis methods
Statistical analysis was performed using the SPSS 22.0 statistical software package. The continuous variables were expressed as mean ± standard deviation ( ±s). The measurement data were analyzed by t test. The qualitative data were analyzed by chi-square test. P < 0.05 was considered statistically signi cant.

Comparison of demographic data and stone characteristics of the two groups
The general conditions and stone characteristics of the two groups were shown in Table 1. There were no signi cant differences in age, gender, BMI, stone size and stone position between the two groups (P > 0.05).

Comparison of intraoperative and postoperative related indexes between the two groups
The intraoperative and postoperative conditions of the two groups were shown in Table 2. There were no signi cant differences in the operation time, puncture position, hemoglobin decline, VAS score on the day − x of discharge, postoperative fever rate, and clear stone rate. No blood transfusion and interventional hemostasis were performed in either group. All patients had no pneumothorax or delayed bleeding. The stones under the guidance of B-ultrasound during surgery were completely removed. With respect to stone removal rates, differences between the two groups were not statistically signi cant (P > 0.05) after the rst operation. The maximum diameter of all the residual stones was less than 4 mm. The average postoperative hospital stay in group 2 was signi cantly longer than in group 1 (P = 0.004). There were signi cant differences in VAS scores between the two groups at 6 h postoperatively (P = 0.035) and on the rst postoperative day (P = 0.034). However, there was no signi cant difference in VAS scores on the day of discharge (P = 0.211). And the two groups of patients were statistically signi cant in the use of analgesic drugs (P = 0.042).

Discussion
With the concept of rapid rehabilitation surgery [7] , minimally invasive surgery has gradually been valued by surgeons. The choice of anesthesia is also an important part of rapid rehabilitation surgery. The kidney and ureter are subject to sympathetic and parasympathetic innervation. The sensory nerves follow the sympathetic and parasympathetic branches. The kidneys and ureters are not sensitive to cauterization and cutting. They are mainly sensitive to traction and increased ureteral pressure in the renal pelvis. The pain is generally dull, which may be associated with sympathetic stimulation, such as bloating, nausea, vomiting and so on. Because of these characteristics of the distribution of urinary nervous system, local anesthesia can meet the surgical requirements. Most hospitals use epidural anesthesia or general anesthesia for surgery. However, compared with epidural and general anesthesia, local anesthesia has the lowest complication and mortality [8] in our hospital. Most patients underwent PCNL under local anesthesia, except for infants and young children. The results of this study show that PCNL under local anesthesia has the following advantages: Firstly, PCNL can avoid the bad impact on cardiopulmonary function of patients under local anesthesia. Secondly, pethidine hydrochloride has a good effect on internal organs pain, and lidocaine has a good effect on the pain caused by puncture [9] . Communicating with the patient during the operation can relieve the patient's nervousness and anxiety in time so that the patient can better tolerate and cooperate with the operation. In epidural anesthesia, due to visceral re ex pain, anesthesiologists are accustomed to use sedative drugs. Patients are often prone to restlessness, position changes which affect surgical operations. Thirdly, patients do not need enema and fasting before surgery and can eat immediately after surgery; Last but not least, PCNL under local anesthesia can reduce treatment costs and hospital stays. The results of this study show that PCNL has a wide range of indications under local anesthesia, and patients can tolerate except for infants and young children. The minimum age of this group is 20 years old and the maximum age is 78 years old. All patients have successfully completed the operation. Some patients who cannot use epidural anesthesia and general anesthesia can also perform PCNL in local anesthesia. In this group of,2 patients aged 78 years old were completed by PCNL under local anesthesia The contraindications for PCNL under local anesthesia in addition to infants and young children are the same as conventional PCNL.
PCNL is the preferred method for the treatment of kidney stones and partial ureteral stones which were larger than 2 cm in diameter. In recent years, studies have reported the use of new technologies and improved protocols, such as minimally invasive PCNL, tubeless PCNL, and PCNL under local anesthesia to reduce postoperative analgesia and hospital stay [10,11] . The tubeless PCNL was rst proposed by Bellman et al [12] in 1997. Since then, research reports on the safety and effectiveness of tubeless PCNL have emerged. There are some advantages of tubeless PCNL group over traditional PCNL including faster recovery, shorter hospital stays, lower hospitalization costs, less postoperative pain, less analgesic drugs usage [13] . But there was no difference between the two groups in postoperative complication. Recently, Shen and Zhong et al [14,15] compared the tubeless PCNL with the common PCNL by meta-analysis, which con rmed that the postoperative analgesia requirement of the tubeless PCNL was lower and the hospital stay was shorter. And in recent years, the application of tubeless PCNL has become more and more extensive, including bilateral kidney stones and isolated kidney stones [16,17] .
The results of this study showed that the operation time of group 2 was slightly longer than the group 1, which mainly because it took a certain time to place and x the stula. But the operation time between the two groups was not signi cantly different. In the postoperative hospital stay, group 2 was signi cantly longer than group 1, which was consistent with the current study results. The postoperative pain VAS score of group 2 was signi cantly higher than group 1. The reasons are as follows: First, the sputum tube stimulates the intercostal or subcostal nerve; Second, The stula tube produces irritation to the renal pelvis and renal pelvis wall. Pain after PCNL is generally mild, and most of them can be relieved without treatment or non-steroidal drugs. Only a small number of patients required narcotic analgesia. Group 2 patients with narcotic analgesic drugs were signi cantly more than group 1, the difference was statistically signi cant, and which was consistent with the VAS score. The reason why the postoperative hospital stay of group 1 was signi cantly shorter than that of group 2 was mainly because we routinely indwelled the stula for 4 ~ 5 days. Furthermore, after extubation, patients were generally observed after 1 day and then discharged. However, patients with untreated PCNL are usually discharged on the third day after surgery if they are asymptomatic. The removal of the renal stula was generally performed without the fever, pain and urine leakage after the clamped tube, so the VAS score at the time of discharge was not signi cantly different between the two groups. There were no blood transfusion, interventional hemostasis, pneumothorax and delayed bleeding in all patients. With respect to puncture site, hemoglobin decline, postoperative fever rate between the two groups were not signi cantly different.
No blood transfusion and interventional hemostasis were performed in either group, and no pneumothorax or delayed bleeding occurred in all patients.
In this study, 135 patients underwent mPCNL under local anesthesia with no serious complications and rapid postoperative recovery. This study showed that PCNL surgery under local anesthesia is simple, safe and effective, and worthy of clinical application. Tubeless mPCNL treatment of kidney stones can signi cantly reduce postoperative pain and discomfort and shorten hospital stays. But it is a retrospective study with possible selection bias, it is necessary to avoid some syndromes, such as intraoperative bleeding, ureteral obstruction, severe perforation of the collection system and residual stones.

Conclusion
Tubeless mPCNL is a simple, safe and effective technique under local anesthesia. It is worthy of clinical application. Tubeless mPCNL treatment for renal stones can signi cantly reduce postoperative pain and shorten hospital stays compared with common m PCNL.