A case of superselective transcatheter embolization for injured renal segmental artery associated with percutaneous nephroureterolithotomy (PNL)

A case in which the renal segmental artery was injured due to percutaneous nephroureterolithotomy (PNL) and treated by superselective transcatheter embolization is reported. The patient was a 30-year-old man with left ureteral and bilateral renal calculi. The left renal and ureteral calculi were successfully removed by PNL and a 24Fr. nephrostomy catheter was placed for 8 days after PNL. A few minutes after removal of the nephrostomy catheter, arterial bleeding, which seemed to occur due to injury of renal segmental artery associated with PNL, began. The bleeding was stopped by replacement of a 24Fr. nephrostomy catheter and the patient received 5 units of packed red blood cells. Six days after hemorrhage, superselective transcatheter embolization was performed. No further bleeding occurred and the nephrostomy catheter was removed 2 days later without any incident. This interventional technique is safe and useful to control bleeding from renal segmental artery injured by PNL.     

Clinical results of extracorporeal shock-wave lithotripsy (ESWL) and percutaneous nephroureterolithotripsy (PNL) in combination

Forty-two (44 renal units) were treated by combination of ESWL and percutaneous nephrostomy or PNL. Staghorn calculi were found in 33, renal stones in 6 and ureter stones in 5. Residual stone rate was 18.2% in staghorn calculi. No severe complications were seen.     

Results of treatment of renal calculi with lower-pole fluoroscopically guided percutaneous nephrolithotomy

Objective:   To prospectively assess the clinical efficacy and safety of lower-pole fluoroscopically guided percutaneous nephrolithotomy (PNL).
Methods:   A total of 90 renal units in 87 patients underwent lower-pole fluoroscopically guided PNL for renal calculi. The average patient age was 56.0 years. Staghorn calculi were present in 41 renal units. There were 22 were upper pole, 54 middle pole, 76 lower pole, 70 pelvic and 18 ureteropelvic junction calculi. Patients without significant residual fragments greater than 3mm on postoperative day 2 were defined as primarily successful. Significant residual fragments were treated with shock wave lithotripsy (SWL) every other day from postoperative day 3.
Results:   Mean operative time was 129.5 min (SD, 49.0). Blood transfusion was required in four patients. Septic shock developed in three patients. Sixty-three percent of the patients (57 of 90 procedures) were primarily successful after PNL: 83.7% of non-staghorn patients (41 of 49 procedures) and 39.0% of staghorn patients (16 of 41 procedures). Of the 33 patients with significant residual fragments, 13 staghorn and six non-staghorn patients had residual fragments in their middle calyces. Of the preoperative variables, staghorn calculus and calculus in the middle calyx were significant predictors of significant residual fragments after PNL. After adjunctive SWL, the overall success rate was 94.5%.
Conclusions:   Our study suggests that lower-pole fluoroscopically guided PNL is a safe and effective therapy for patients with staghorn or non-staghorn calculi. In patients with staghorn calculi or calculi in the middle calyx, adjunctive treatment is sometimes required to treat significant residual fragments.     

Bilateral percutaneous nephrolithotomy in a patient with hemophilia A disorder

A 50-year-old man with hemophilia A presented with recurrent hematuria due to renal stone disease. He was receiving approximately 50,000 units of recombinant factor (rF) VIII concentrate every year due to hematuria. Between 1996 and 2002, his serum creatinine level increased from 0.7 to 1.2 ng/ml. In an effort to resolve the problems of excessive blood loss with transfusions, recurrent rF VIII replacements and deteriorating renal function, he was offered treatment with percutaneous nephrolithotomy (PNL) in conjunction with rF VIII administration. He underwent left PNL for left staghorn calculi in November 2002 with administration of 52,000 units rF VIII, and another PNL for the right kidney in April 2004 with the administration of 90,500 units rF VIII. A pneumatic lithotriptor was used in both operations. The serum creatinine level was 0.8 ng/ml upon completion of treatment and the patient was symptom and stone free at 10-month follow-up. He has not suffered from hematuria since that time. We conclude that bleeding disorders may not be a contraindication for PNL if corrected and monitored appropriately.     

Ureolytic Citrobacter freundii infection of the urine as a cause of dissolution of cystine renal calculi

We report a case of cystinuria with staghorn renal lithiasis in a solitary right kidney and chronic renal failure. Right nephropyelolithotomy was performed and although 29 renal calculi were extracted many stones remained in situ. A permanent nephrostomy was left in the kidney. Several months later the urine was infected chronically with a ureolytic Citrobacter freundii bacteria and urinary pH oscillated between 8.0 and 9.2. Spontaneous dissolution of the cystine calculi was observed and many tiny fragments of cystine were expulsed through the nephrostomy, following which renal function improved. Despite the conditions favoring struvite calculi, formation did not occur.     

Primary extracorporeal shock wave lithotripsy of staghorn renal calculi.

186 patients with partial and 55 patients with complete renal staghorn calculi were treated with primary extracorporeal shock wave lithotripsy (ESWL) at the Department of Urology, University of Würzburg Medical School. Partial staghorn calculi required an average of 1.4, complete staghorn calculi an average of 2.2 treatment sessions using the Dornier HM 3 lithotriptor. 55% of all patients and 46% of the patients with complete staghorn calculi were rendered stone-free within 1 year after ESWL. Pretreatment urinary tract infections present in 50.6% of all patients could be reduced to 22.5% 1 year after ESWL. The most frequent complications after ESWL were ureteral obstruction caused by 'steinstrasse' (41.4%), fever (38.4%), and renal colics (29.4%). Severe complications needing open operative procedures or blood transfusions did not occur. 50% of all patients underwent auxiliary procedures (e.g. insertion of indwelling ureteral stents: 25.3%, percutaneous nephrostomy: 20.3%, percutaneous nephrolithotripsy: 2.9%). Pretreatment insertion of an indwelling ureteral stent was found to reduce posttreatment complications as well as the need for percutaneous nephrostomy only in patients with partial staghorn calculi. The data presented in this study demonstrate that primary ESWL therapy can be safely and successfully performed in the majority of patients with renal staghorn calculi. In patients requiring complete removal of all stone fragments, a percutaneous lithotripsy can be performed following ESWL.     

The influence of percutaneous nephrolithotomy on renal function evaluated by 99m-Tc-DTPA renoscintigram

The influence of percutaneous nephrolithotomy (PNL) on renal function was evaluated by 99m-Tc-DTPA renoscintigraphy. The renoscintigram was recorded and regions of interest of both kidneys (R) and background (BKG) were settled. Renal uptake ratio was calculated by the following formula. Renal uptake ratio = (formula; see text). The renal uptake ratio of 50 patients were compared before and up to 6 months after PNL. Most cases showed an increase or no change in post-PNL renal uptake ratio in operated kidney. Five cases (10%) showed decreased renal uptake ratio of post-PNL. No risk factors for the renal damage caused by PNL such as age, sex, stone size, number of nephrostomy and course of PNL were detected when compared with increased or no change groups. In cases of complete staghorn calculi in the decreased renal uptake ratio group, compensatory hypertrophy of contralateral kidney PNL course might occur, and the function of the operated kidney might not have recovered. More during cases and longer follow-up is necessary for the recovery of renal function.     

三种经皮肾穿刺取石术治疗上尿路结石对照分析

目的：比较李氏肾镜与标准经皮肾镜及微创经皮肾输尿管镜治疗上尿路结石的有效性与安全性,提高上尿路结石的治疗水平.方法：2005年1月～2009年1月,三种经皮肾穿刺取石术治疗上尿路结石132例,其中包括肾结石87例（包括肾脏单发及多发结石56例,鹿角型结石31例）,输尿管上段结石45例.标准经皮肾镜取石术34例,年龄34～78岁,平均57岁;结石大小2.3～5.8 cm,平均3.5 cm;鹿角型结石14例.微创经皮肾输尿管镜取石术52例,年龄31～77岁,平均51岁;结石大小2.1～5.0 cm,平均3.3 cm;鹿角型结石8例.经皮李氏肾镜取石术46例,年龄29～81岁,平均55岁;结石大小2.0～5.5 cm,平均3.0 cm;鹿角型结石9例.对三组患者手术时间、留置造瘘管时间、I期结石清除率及手术出血进行比较.结果：李氏肾镜治疗输尿管上端结石（L4）手术时间（56±5）min,治疗上尿路结石I期手术清除率为80.43%,出血量为（156±38）ml,输血率2.17%,与标准经皮肾镜及微创经皮肾输尿管镜比较,差异均有统计学意义（P＜0.05）.对李氏肾镜治疗6例肾盂单发结石患者实行＂无管化＂,均恢复较好,无一例发生出血、漏尿及感染.结论：李氏肾镜在微造瘘经皮肾手术中较标准肾镜和输尿管镜代肾镜具有操作更简化、手术效率更高、剩余结石更少、并发症减少等优点.     

Clinical results of percutaneous nephroureterolithotripsy

Thirty-five patients (37 renal units) were treated by PNL. Nine had complete staghorn calculi, 2 multiple reno-ureteral stones, 12 solitary renal stone, and 14 upper ureteral stone. The success rate was 94.6%. No severe complications were seen.     

经皮肾镜联合不同软镜治疗鹿角形肾结石的研究

目的：评价单通道经皮肾镜联合不同软镜下钬激光碎石治疗鹿角形肾结石的手术效果。方法：B超引导穿刺,单通道经皮肾镜联合膀胱软镜和输尿管软镜,行钬激光碎石治疗鹿角形。肾结石93例。结石直径2．6～5．4cm。结果：93例均采用单通道经皮。肾镜联合软镜下钬激光碎石,一期手术平均手术时间为108min,完全清除率为83．9％（78／93）,二期手术平均手术时间为43min,结石完全清除率87．5％（7／8）。全部病例均无肾盂穿孔、气胸、腹腔内脏器官损伤等严重并发症发生。结论：单通道经皮。肾镜联合不同软镜下钬激光碎石治疗鹿角形肾结石具有碎石成功率和结石排净率高、创伤小、手术时间短、并发症少、周围脏器损伤风险小等优点,是一种治疗鹿角状肾结石的理想方法。     

Percutaneous nephrolithotomy. With emphasis on large renal stones

With utilization of safety guide wire, dilator (up to 36F), and Mazzariello-Caprini forceps, percutaneous removal of renal stone was successfully performed in 18 cases, including 5 cases with staghorn calculus, although parts of the staghorn calculus were left in 4 cases. Attempts at stone extraction were performed on the day nephrostomy was made. All of the renal stones excluding staghorn calculi were removed without disruption followed by satisfactory postoperative renal function. Unexpectedly Kocher forceps was found to be a useful and relatively safe instrument for quick fragmentation and removal of staghorn calculi.     

Retrograde nephrostomy for percutaneous nephrolithotomy

Between June, 1985 and November, 1986, 25 patients at our institute underwent retrograde nephrostomy placement to provide percutaneous access to the kidney for percutaneous nephrolithotomy (PNL) of renal or upper ureteral calculi. Overall, retrograde nephrostomy was successfully completed through the desired calyx in 80% of the patients and calculi were successfully removed by the subsequent PNL. There were 5 failures primarily due to wrong indication and inexperience with the technique. The procedures had been done without significant complications in this series including unsuccessful cases. On the basis of our experiences, it is practically important for successful retrograde nephrostomy to fix the tip of the catheter firmly in the desired calyx until the puncture wire is advanced into the renal parenchyma. It is also important to aim the puncture wire at the skin in a favorable direction to avoid adjacent visceral penetration. Retrograde nephrostomy is a useful aid for percutaneous calculus removal particularly in patients with nondilated intrarenal collecting systems, because this new technique allows precise tract placement to the kidney required for efficient calculus manipulation with less risk than that associated with conventional percutaneous nephrostomy.     

Changes in the management of urolithiasis: endourologic treatment of calculi in the upper urinary tract

Three hundred seventy cases with calculi in upper urinary tract were treated by endourology, 210 cases were subjects of percutaneous nephrolithotripsy (PNL) and 160 cases of transurethral ureterolithotripsy (TUL), in Nara Medical University Hospital and 13 affiliated hospitals. Of the PNL cases, PNL was completed in 184 cases (87.6%) and not completed in 16 cases (12.4%). 168 cases (80.0%) had successful results by PNL alone, stone-free or stone fragments less than 5 mm, in spite of the stone location and size. No serious adverse effect was experienced throughout the study. However, changes like a scar formation or fibrosis around the nephrostomy tract were revealed as a late complication by excretory urography, computed tomography and renal scanning. Of the 160 TUL cases, TUL was successful in 132 cases (82.5%) and unsuccessful in 28 cases (17.5%). The results of TUL for the calculi above the upper iliac cresta were not favorable, success rate for stone 6-10 mm in diameter was 70.3% and that for stones larger than 11 mm 37.5%. However, the results of TUL for the calculi below the upper ileac cresta were favorable, the success rate for the 6-10 mm calculi was 91.5% and for the calculi larger than 11 mm 88.4%. Of 28 TUL failures, 7 cases underwent PNL and 21 cases received open surgery. Throughout our endourologic treatments, the most problematic stone was calculi impact in the ureter. The indication of endourology for the calculi in upper urinary tract is discussed with consideration of ESWL which is becoming the main stream of stone treatment.     

Beyond prone position in percutaneous nephrolithotomy: a comprehensive review

Context

Percutaneous nephrolithotomy (PNL) is traditionally performed with the patient in the prone position.

Objective

To assess the efficacy and safety of the prone and supine positions, particularly in obese patients and in those with staghorn calculi.

Evidence acquisition

A Medline search was conducted for articles published during the last 10 yr related to PNL in the prone and supine positions.

Evidence synthesis

This search revealed 9 published studies for supine and 25 for prone PNL. None of the supine PNL studies reported visceral injuries, while transfusion rates were 0.0–9.4% and stone-free rates were 69.6–95.0%. One study of supine PNL evaluated a significant proportion of obese patients. Prone PNL studies in obese patients report transfusion rates of 3.2–8.8% and stone-free rates of 79.0–89.2%.In the only randomized study, excluding obese patients and staghorn calculi, operative time favors the supine position. A nonrandomized comparative study demonstrated similar complication rates with insignificant improvement in treatment success for supine PNL; however, when comparing series with similar proportions of staghorn calculi cases, there are slightly improved outcomes for prone PNL. Moreover, comparison of weighted means favors prone PNL.

Conclusions

For obese patients and staghorn calculi, prone PNL appears to be associated with decreased operative times with similar bleeding rates and slightly better stone-free rates than supine PNL.     

Critical analysis of supracostal access for percutaneous renal surgery

PURPOSE: Percutaneous renal surgery is currently performed for complex renal calculi as well as for various other endourological indications. In many patients an upper pole nephrostomy tract allows direct access to most of the intrarenal collecting system. Upper pole percutaneous access may be obtained via the supracostal or subcostal approach. The preferred route depends on the location and size of the specific stone or lesion. Previously others have cautioned against the supracostal approach above the 12th rib and many have discouraged an approach above the 11th rib due to concern about the increased risk of intrathoracic complications. We retrospectively assessed the morbidity associated with supracostal percutaneous renal surgery and compared and analyzed the morbidity of the supracostal and subcostal approaches. MATERIALS AND METHODS: The records of all patients who underwent upper pole percutaneous renal surgery between November 1993 and July 1999 were retrospectively reviewed. A total of 240 patients underwent percutaneous renal procedures, including 225 for managing symptomatic renal or ureteral stones, that is nonstaghorn calculi in 157, staghorn calculi in 41, proximal ureteral calculi in 12, calculi within a caliceal diverticulum in 6, calculi associated with primary ureteropelvic junction obstruction in 5 and calculi associated with a retained ureteral stent in 4. An additional 15 procedures were done for ureteropelvic junction obstruction (7), intrarenal collecting system tumors (5), a caliceal diverticulum without stones (1), a retained ureteral stent (1) and a ureteral stricture (1). RESULTS: A total of 300 nephrostomy tracts were placed to obtain access to the intrarenal collecting system via the supracostal approach in 98 (32.7%) cases and the subcostal approach in 202 (67.3%). Of the supracostal approaches 72 (73.5%) tracts were above the 12th and 26 (26.5%) were above the 11th rib. The overall complication rate irrespective of percutaneous approach was 8.3% (16.3% for supracostal and 4.5% for subcostal access). Complications included blood transfusion in 7 patients, intraoperative hemothorax/hydrothorax in 5, sepsis/bacteremia in 3, atrial fibrillation in 2, delayed nephropleural fistula in 2, renal artery pseudoaneurysm in 2, deep venous thrombosis/pulmonary embolus in 2, pneumothorax in 1 and subcapsular hematoma in 1. Seven of 8 intrathoracic complications (87.5%) developed in supracostal cases. CONCLUSIONS: Percutaneous renal surgery remains an important option for managing complex renal calculi and other upper urinary tract lesions. In our experience it is generally associated with low morbidity. The supracostal approach is often preferred for obtaining intrarenal access to complex renal and proximal ureteral pathology. Because supracostal access tracts are associated with significantly higher intrathoracic and overall complication rates compared to subcostal access tracts, this approach must be used with caution when no other alternatives are available.     

Chemolysis of cystine calculi incarcerated in the ureter by the alkaline organic amine, tromethamine-E

We dissolved the cystine calculi incarcerated in the ureter by irrigation with tromethamine-E via percutaneous nephrostomy. Case 1: A 25-year-old man with a past history of cystinuria and staghorn calculi in the right kidney, suffered from obstructive renal failure caused by the incarceration of a stone (18 x 15 mm) in the left middle ureter. After recovering promptly from renal failure by left percutaneous nephrostomy, he received continuous irrigation with tromethamine-E through an angiographic catheter percutaneously placed in the ureter. The ureteral calculus was reduced by 70% in size after the irrigation for 35 days, and then extracted percutaneously. Case 2: A 3-year-old child had multiple cystine calculi in the right renal pelvis and ureter. Although a calculus in the renal pelvis was extracted by the percutaneous ultrasound lithotripsy, two calculi incarcerated in the middle ureter were impossible to remove by a percutaneous approach. The irrigation with tromethamine-E was initiated through the catheter placed percutaneously in the right ureter. Both calculi completely dissolved 47 days later. The chemolysis by irrigation with tromethamine-E was greatly valuable in the treatment of cystine calculi. This dissolution could be an alternative to surgery especially in the treatment of ureteral cystine calculi, which might be difficult to be extracted by the percutaneous or transurethral approach.     

Extracorporeal shock wave lithotripsy of staghorn stones in solitary kidney]

Extracorporeal shock wave lithotripsy (ESWL) has been established as noninvasive treatment of choice for the great majority of upper urinary tract stones. However the management of staghorn stones in solitary kidney still deserves special consideration. We reviewed retrospectively 11 patients with staghorn stones in solitary kidney treated mainly with the Dornier HM-3 lithotripter during the period between December 1984 and December 1989 at the Sagamidai Hospital. The contralateral kidneys of the 8 patients were nephrectomized or nonfunctioning due to stone disease and those of 3 patients were nephrectomized due to tuberculosis. They were consisted of 6 males and 5 females with average ages of 60.0 years and 48.6 years respectively. The size of the stones ranged from 30 x 30 mm to 85 x 40 mm in KUB. ESWL was the first treatment for all the cases except for one patient a cystine stone. In that patient, ESWL was preceded by percutaneous nephrolithotripsy (PNL). In three patients the treatment was successfully by ESWL alone without any obvious complication. In 6 patients percutaneous nephrostomy was required and in two patients PNL was performed as an auxiliary procedure. Seven patients developed high fever (over 38.5 degrees C) and two of them became septic during the course of treatment. In five patients serum creatinine elevated over 2.0 mg/dl, but returned to within normal limits postoperatively. Extracorporeal shock wave lithotripsy can play a major role in the patient of the staghorn stones in solitary kidney.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical experience of extracorporeal shock wave lithotripsy for cystine calculi

Thirty patients (16 men and 14 women) with cystine urinary stones were treated by extracorporeal shock wave lithotripsy (Dormer HM-3) from December 1984 through October 1989. The average patient age was 35.2 years with a range of 14 to 59 years. Seventy per cent of these subjects had had previous open surgical operations for stones. The cases consisted of 7 ureteral stones and 37 renal stones, including 15 staghorn calculi. An average of 1.3 session of ESWL was carried out to treat ureteral stones. Thirty-seven renal units with renal stone required 96 sessions of lithotripsy (average 2.6 sessions per unit). Seven patients with ureteral stones required auxiliary procedures, i.e., one transurethral lithotripsy (TUL), two percutaneous nephrostomies (PNS) and one open surgery. Thirty-seven renal stones, including staghorn calculi was treated by ESWL and auxiliary treatment of 21 TUL procedures, one PNS, 16 PNL procedures and one chemical chemolysis. Successful fragmentation (residual debris less than or equal to 4 mm) was achieved in 85.7% of ureteral stones, 90.9% of renal stones and 73.3% of staghorn calculi. The stone free rates of patients with ureteral stones, renal stones and staghorn calculi were 71.4%, 50.0% and 53.5%, respectively, at 3 months after ESWL. No serious complications were seen in this series. Fever above 38.5 degrees C was the most common complications (13.5%). Ureteral perforation was encountered once in TUL procedures. Transfusion and selective arterial embolization were needed for one case treated by PNL procedures. Although cystine stone is harder to be fragmented by ESWL than other stone composition, ESWL and endourology may be effective and safe procedures for cystine stone patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Combined percutaneous and retrograde approach to staghorn calculi with application of the ureteral access sheath to facilitate percutaneous nephrolithotomy

PURPOSE: We describe our technique and clinical experience with application of the ureteral access sheath for single access ablation of staghorn and partial staghorn calculi. MATERIALS AND METHODS: We retrospectively reviewed our experience with 9 patients who underwent percutaneous nephrolithotomy for staghorn (6) or partial staghorn (3) renal calculi using a combined antegrade and retrograde approach. Patient data, operative parameters, efficacy of stone ablation and convalescence parameters were reviewed. RESULTS: Mean operative time for the primary procedure was 3.1 hours with a mean estimated blood loss of 290 ml. Postoperatively, the mean analgesic requirement was 33.2 mg. MSO(4) equivalents. Hospital stay was 3.2 days. There were no major and 4 minor (44%) complications. No patient required transfusion. Complete stone clearance was achieved in 7 of the 9 cases (78%) using a single percutaneous nephrostomy tract. CONCLUSIONS: Our preliminary clinical experience using the ureteral access sheath during percutaneous nephrolithotomy for simultaneous antegrade and retrograde stone treatment has been favorable. A large renal stone burden can be successfully managed with a single percutaneous access and limited blood loss.     

PERCUTANEOUS NEPHROLITHOTOMY IN THE PEDIATRIC POPULATION

PURPOSE: Percutaneous nephrolithotomy is an established technique used in children with renal calculi. We review our experience with percutaneous nephrolithotomy for treating nephrolithiasis in childhood. MATERIALS AND METHODS: We retrospectively reviewed the records of children who underwent percutaneous nephrolithotomy procedures for renal calculi from 1985 to 1996. Antegrade percutaneous access was obtained in all patients and the tract was dilated to 24F. Grasper forceps, ultrasound and/or electrohydraulic lithotripsy was used to remove and disintegrate stones. In all patients a nephrostomy tube was placed intraoperatively, and a plain abdominal x-ray and nephrostogram were done postoperatively. The nephrostomy tube was removed after ensuring free drainage down the ureter and no untoward effects from clamping. Complete anatomical and metabolic evaluation was performed in all cases. Patients were followed 2 to 6 weeks, and 3 and 6 months postoperatively with a plain abdominal x-ray and excretory urography or renal ultrasound. RESULTS: In 5 boys and 3 girls (9 renal units) 4 to 11 years old (mean age 6.4) a total of 10 percutaneous nephrolithotomy procedures were performed. At presentation 6 children had flank and/or abdominal pain, 5 gross hematuria and 3 urinary tract infection. Three patients had associated metabolic abnormalities. One patient with a staghorn calculus had hydronephrosis and multiple infundibular stenoses. No underlying urological anatomical abnormalities were noted in the remaining cases. Four renal units that were obstructed at presentation required initial nephrostomy tube insertion. Average operative time was 131.8 minutes (range 58 to 240). An 87.5% stone-free rate was achieved using percutaneous nephrolithotomy monotherapy. Percutaneous nephrolithotomy was not successful for eradicating a staghorn stone in 1 patient. Hypothermia developed in 2 patients in whom operative time exceeded 150 minutes. No blood transfusions were required. CONCLUSIONS: Percutaneous nephrolithotomy is safe and effective in children, and should be considered a viable management option. However, staghorn calculi may require alternative management, particularly in the setting of underlying anatomical abnormalities. Children with renal calculi should undergo a complete anatomical and metabolic assessment with the institution of medical therapy, as appropriate.