Acid-base and electrolyte disorders after urinary diversion

Multidisciplinary management of people with spina bifida across the lifespan

The average worldwide prevalence of neural tube defects (NTDs) is 1.0 per 1000 births. Its development is multifactorial due to genetic and non-genetic factors. Spina bifida (SB) is one of main representatives of NTD. The spinal cord lesion level is the main determinant of the level of paralysis, numbness, and difficulties with bladder/bowel functions. Myelomeningocele prenatal repair reduces hydrocephalus and hindbrain herniation and improves motor function. The severity of hydrocephalus is associated with poorer neurodevelopmental outcomes whether operated on prenatally or after birth. People with SB tend to have a lower IQ and cognitive difficulties. Early diagnosis, proactivity, and lifelong multidisciplinary follow-up are key protective issues. Invasive urological interventions should be considered in selected patients after failure of conservative treatment. Transition to adult care should be well planned as it is challenging. Health literacy is directly associated with success at transition. Sexuality and fertility should be addressed before/during puberty. Overall, the rates of fecal and urinary continence and skin breakdown increase with age, whereas the ability to ambulate declines with age. Bowel and urinary incontinence are independent predictors of lower health-related quality of life (HRQoL) in adults with SB. Bowel incontinence has negative impact on HRQoL regardless of frequency or amount. Long-term caregiver support should be offered at diagnosis. Survival at a mean of 50 years is poor, at 32%, due to central nervous system deaths, cancer, urological disease, and sepsis. Challenges to implementation of recommended practices exist, especially in low and middle-income countries.

Stoma-related complications and emergencies

Stoma creations are common procedures in surgical specialties. They can be created either as a temporary or a permanent measure. Despite advancements in surgical technique and stoma care, complications are common. Patients experiencing stoma-related complications often present to the emergency department. Emergency physicians are not expected to be stoma experts, yet they are often the first point of contact for patients experiencing stoma-related complications. Accordingly, emergency physicians should be familiar with the types of stomas and complications and emergencies associated with them so that they can appropriately address the problems related to stomas. This article will provide a review of emergencies and complications associated with ileostomies, colostomies, and urostomies.

Neglected analytes in the 24-h urine: ammonium and sulfate

PURPOSE OF REVIEW

Evaluation of the kidney stone patient includes measurement of 24 h urine chemistries. This review summarizes the application of physiologic principles to the interpretation of urine chemistries, using sulfate and ammonium to estimate diet acid load, and the renal response.

RECENT FINDINGS

There has been increased recognition of the need to measure urine ammonium excretion in the clinical setting in order to understand renal acid excretion. Some 24 h urine kidney stone panels include ammonium measurements, providing an opportunity to apply this measurement to clinical practice. In order to better interpret ammonium excretion, one needs an estimate of dietary acid load to understand the driving forces for ammonium excretion. Sulfate is also included in some kidney stone panels and functions as an estimate of diet acid load. Combining these analytes with urine pH, the clinician can quickly estimate dietary stone risk as well as potential bowel disease, acidification disorders, and the presence of urease producing bacteria; all of which can affect stone risk.

SUMMARY

Measurement of ammonium and sulfate excretion along with urine pH provide important insights into the acid/alkali content of diet, presence and severity of bowel disease, presence of renal acidification disorders, and urinary infection.

Studying the electrolyte changes in ileal urine at the time of radical cystectomy and ileal conduit diversion

To the Editor, Radical cystectomy (RC) for bladder cancer is a life-changing surgery, associated with high morbidity and mortality rate. Ileal neobladder seems as an attractive way for urine management post cystectomy but would carry the risk of retaining urine in the ileal pouch for a long time, resulting in serum electrolyte changes, that may add to the patients' morbidity. EAU guidelines recommend against ileal neobladder for patients with liver and renal disorders, as well as for patients > 80 years old [...].

Use of Lactulose to Treat Hyperammonemia in ICU Patients Without Chronic Liver Disease or Significant Hepatocellular Injury

OBJECTIVES

To review ICU patients with elevated ammonia without a clear hepatic etiology, to compare outcomes between those who received lactulose and those who did not.

DESIGN

Retrospective observational study.

SETTING

Medical, surgical, and subspecialty intensive care units at Wake Forest Baptist Medical Center, Winston-Salem, North Carolina between December 2012 and August 2016.

PATIENTS

Adults with ammonia levels above 50 μmol/L, excluding those with known chronic liver disease, inborn error of metabolism, active use of valproic acid, total bilirubin ≥ 2 μmol/L, or alanine aminotransferase ≥ 100 units/L.

INTERVENTIONS

Comparison in ICU length of stay (LOS), hospital LOS, in-hospital mortality, and mortality at 30 and 90 days.

MEASUREMENTS AND MAIN RESULTS

Criteria for inclusion were met in 103 cases. Mean ammonia level was 75 μmol/L, with undetermined etiology in the majority of subjects. Lactulose was given in 48 cases (46.6%), with a median of 9.5 doses given. There were no significant differences in outcomes between the lactulose and non-lactulose groups. Among subjects with multiple data points, lactulose did not have a dose-dependent effect on ammonia level, and was not associated with faster ammonia normalization compared to non-lactulose. When analyzed separately, patients with moderate hyperammonemia (60-99 μmol/L) who received lactulose had longer hospital and ICU length of stay compared to non-lactulose (417.8 hours vs. 208.4 hours, P = 0.003, and 229.2 hours vs. 104.7 hours, P = 0.025; respectively), though confounders were present.

CONCLUSIONS

Routine use of lactulose to treat mild to moderate hyperammonemia in this patient population was not associated with improved outcomes.

Hyperchloremic normal gap metabolic acidosis

Metabolic acidosis is defined as a pathologic process that, when unopposed, increases the concentration of hydrogen ions (H+) in the body and reduces the bicarbonate (HCO3-) concentration. Metabolic acidosis can be of a kidney origin or an extrarenal cause. Assessment of urinary ammonium excretion by calculating the urine anion gap or osmolal gap is a useful method to distinguish between these two causes. Extrarenal processes include increased endogenous acid production and accelerated loss of bicarbonate from the body. Metabolic acidosis of renal origin is due to a primary defect in renal acidification with no increase in extrarenal hydrogen ion production. This situation can occur because either the renal input of new bicarbonate is insufficient to regenerate the bicarbonate lost in buffering endogenous acid as with distal renal tubular acidosis (RTA) or the RTA of renal insufficiency, or the filtered bicarbonate is lost by kidney wasting as in proximal RTA. In either condition, because of loss of either NaHCO3 (proximal RTA) or NaA (distal RTA), effective extracellular volume is reduced and as a result the avidity for chloride reabsorption derived from the diet is increased and results in a hyperchloremic normal gap metabolic acidosis. The RTA of renal insufficiency is also characterized by a normal gap acidosis, however, with severe reductions in the glomerular filtration rate an anion gap metabolic acidosis eventually develops.

Directed differentiation of human induced pluripotent stem cells into mature stratified bladder urothelium

For augmentation or reconstruction of urinary bladder after cystectomy, bladder urothelium derived from human induced pluripotent stem cells (hiPSCs) has recently received focus. However, previous studies have only shown the emergence of cells expressing some urothelial markers among derivatives of hiPSCs, and no report has demonstrated the stratified structure, which is a particularly important attribute of the barrier function of mature bladder urothelium. In present study, we developed a method for the directed differentiation of hiPSCs into mature stratified bladder urothelium. The caudal hindgut, from which the bladder urothelium develops, was predominantly induced via the high-dose administration of CHIR99021 during definitive endoderm induction, and this treatment subsequently increased the expressions of uroplakins. Terminal differentiation, characterized by the increased expression of uroplakins, CK13, and CK20, was induced with the combination of Troglitazone + PD153035. FGF10 enhanced the expression of uroplakins and the stratification of the epithelium, and the transwell culture system further enhanced such stratification. Furthermore, the barrier function of our urothelium was demonstrated by a permeability assay using FITC-dextran. According to an immunohistological analysis, the stratified uroplakin II-positive epithelium was observed in the transwells. This method might be useful in the field of regenerative medicine of the bladder.

Use of Bowel in Reconstructive Urology: What a Colorectal Surgeon Should Know

Urologists routinely use bowel in the reconstruction of the urinary tract. With an increasing prevalence of urinary diversions, it is important for surgeons to have a basic understanding of varied use and configuration of bowel segments in urinary tract reconstruction that may be encountered during abdominal surgery. The aim of this review article is to provide an overview of the various reconstructive urological surgeries requiring bowel and to guide physicians on how to manage these patients with urinary diversions.

Long-term complications arising from bowel interposition in the urinary tract

After radical cystectomy or pathologies affecting the ureter(s), bowel segments can be employed to restore the natural urine flow or to create an external urinary diversion. Nevertheless, the interposition of bowel segments in the urinary tract is not devoid of complications. In fact, bowel's microstructure differs from the urothelium; specifically its mucosa is aimed at reabsorption, rather than storage. The aim of this paper is to revise the pathophysiology of complications related to bowel's mucosal properties. Those are: metabolic imbalance, malabsorption of vitamins, cholelitiasis, nephrolitiasis and infections. Their entity varies according to the segment used and to its length, which reflects the surface in contact with urine. Mostly, they occur on the long-term, but metabolic imbalances might occur soon after surgery as well.

Metabolic and Electrolyte Abnormalities Related to Use of Bowel in Urologic Reconstruction

Many urologic reconstructive techniques involve the use of autologous bowel for urinary diversion and bladder augmentation. The resection of bowel and its reimplantation into the urinary system often comes with a variety of metabolic and electrolyte derangements, depending on the type of bowel used and the quantity of urine it is exposed to in its final anatomic position. Clinicians should be aware of these potential complications due to the serious consequences that may result from uncorrected electrolyte disturbances. This article reviews the common electrolyte complications related to both bowel resection and the interposition of bowel within the urinary tract.

Is chronic alkali therapy in orthotopic ileal neobladders necessary? A prospective controlled study

PURPOSE

To evaluate the necessity of chronic alkali therapy in non-complicated orthotopic ileal neobladders with normal renal function.

MATERIALS AND METHODS

This is a prospective study that included 200 male patients who underwent radical cystectomy and ileal W neobladder for invasive bladder carcinoma between January 1993 and December 2013. The studied patients included 100 consecutive patients who were maintained on regular alkali therapy since surgery and 100 consecutive patients who stopped the use of alkali treatment after initial 3 months postoperative with minimum postoperative observation time of 1 year. All patients had satisfactory function of the reservoirs with normal upper tract. The patients were subjected to blood analysis for creatnine, electrolytes, pH and bicarbonate and urine chemical analysis. The study also included 40 healthy male age-matched volunteers who served as a control group.

RESULTS

Both groups were comparable as regard age, BMI, follow-up period and surgical technique. There were no significant differences between both groups as regard serum creatnine, electrolytes blood pH and bicarbonate and the mean values were within normal range; however, the neobladder patients are still toward the acidotic side in comparison to healthy volunteers. Also there were no significant differences between both groups of patients as regard urine pH and excretion of electrolytes, calcium, phosphorus and creatnine.

CONCLUSION

Patients with non-complicated ileal neobladders with normal upper tract who were not maintained on alkali prophylaxis for long period have a compensated acid base status. Therefore, the prolonged alkali prophylaxis is not mandatory.

Production of urothelium from pluripotent stem cells for regenerative applications

As bladder reconstruction strategies evolve, a feasible and safe source of transplantable urothelium becomes a major consideration for patients with advanced bladder disease, particularly cancer. Pluripotent stem cells, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are attractive candidates from which to derive urothelium as they renew and proliferate indefinitely in vitro and fulfill the non-autologous and/or non-urologic criteria, respectively, that is required for many patients. This review presents the latest advancements in differentiating urothelium from pluripotent stem cells in vitro in the context of current bladder tissue engineering strategies.

Regenerative medicine in urology

Repair and reconstruction of damaged tissues and organs has been a major issue in the medical field. Regenerative medicine and tissue engineering, as rapid evolving technologies, may offer alternative treatments and hope for patients with serious defects and end-stage diseases. Most urologic diseases could benefit from the development of regenerative medicine and tissue engineering. This article discusses the role of cells and materials in regenerative medicine, as well as the status of current role of regenerative medicine for the generation of specific urologic organs.

Metabolic consequences after urinary diversion

Metabolic disturbances are well-known, but sometimes neglected immediate consequences or late sequelae following urinary diversion (UD) using bowel segments. Whereas subclinical disturbances appear to be quite common, clinically relevant metabolic complications, however, are rare. Exclusion of bowel segments for UD results in loss of absorptive surface for its physiological function. Previous studies demonstrated that at least some of the absorptive and secreting properties of the bowel are preserved when exposed to urine. For each bowel segment typical consequences and complications have been reported. The use of ileal and/or colonic segments may result in hyperchloremic metabolic acidosis, which can be prevented if prophylactic treatment with alkali supplementation is started early. The resection of ileal segments may be responsible for malabsorption of vitamin B12 and bile acids with subsequent neurological and hematological late sequelae as well as potential worsening of the patient's bowel habits. Hence, careful patient and procedure selection, meticulous long-term follow-up, and prophylactic treatment of subclinical acidosis is of paramount importance in the prevention of true metabolic complications.

Urinary diversion--approaches and consequences

BACKGROUND

Bladder cancer is not a rare disease: In 2010, there were more than 70 000 affected patients in the United States. Radical cystectomy for the treatment of muscle invasive bladder cancer necessitates urinary diversion.

METHODS

We present the current options for urinary diversion and their different indications on the basis of a selective search for pertinent literature in PubMed and our own clinical experience.

RESULTS

When bladder cancer is treated with curative intent, continence-preserving orthotopic urinary bladder replacement is preferred. For heterotopic urinary bladder replacement, a reservoir is fashioned from an ileal or ileocecal segment. Urine is diverted to the rectum by way of the sigmoid colon. When bladder cancer is treated with palliative intent, non-continence-preserving cutaneous urinary diversion is usually performed: The creation either of a renal-cutaneous fistula or a self-retaining ureteral stent is a purely palliative procedure. In these interventions, the resorptive surface of the bowel segment used can no longer play its original physiological role in the gastrointestinal tract, even though its absorptive and secretory functions are still intact. This has metabolic consequences, because the diverted urine here comes into contact with a large area of bowel epithelium. Early preventive treatment must be provided against potentially serious complications such as metabolic acidosis and loss of bone density. The resection of ileal segments can also lead to malabsorption. The risk of secondary malignancy is elevated after either continence-preserving anal urinary diversion (>2%) or bladder augmentation (>1%).

CONCLUSION

There are four options for urinary diversion after cystectomy that can be performed when surgery is performed with either curative or palliative intent. There are also a number of purely palliative interventions.

Tissue engineering for the oncologic urinary bladder

Urinary diversion after radical cystectomy in patients with bladder cancer normally takes the form of an ileal conduit or neobladder. However, such diversions are associated with a number of complications including increased risk of infection. A plausible alternative is the construction of a neobladder (or bladder tissue) in vitro using autologous cells harvested from the patient. Biomaterials can be used as a scaffold for naturally occurring regenerative stem cells to latch onto to regrow the bladder smooth muscle and epithelium. Such engineered tissues show great promise in urologic tissue regeneration, but are faced with a number of challenges. For example, the differentiation mesenchymal stem cells from various sources can be difficult and the smooth muscle cells formed do not precisely mimic the natural cells.

[Metabolic long-term complications after urinary diversion]

Metabolic long-term complications and consequences after urinary diversion are somewhat neglected. Subclinical metabolic disturbances are quite common; however, complications are rare. The absorptive surface of the bowel segment is lost for the physiological function of the gastrointestinal tract. Some studies demonstrated that at least some of the absorbent and secreting properties of the bowel are preserved if exposed to urine. For each bowel segment typical complications are reported. Using ileal and/or colon segments, hyperchloremic metabolic acidosis may occur. Studies demonstrated that metabolic effects are not as severe as suspected and could be prevented if a prophylactic treatment is started early.The resection of ileal segments is responsible for malabsorption of vitamin B(12) and bile acid; when using colonic segments, electrolyte disturbances are more common. Careful patient selection, meticulous follow-up and prophylactic treatment are crucial to prevent metabolic complications.

Bladder augmentation and urinary diversion in patients with neurogenic bladder: non-surgical considerations

Segments from almost all parts of the bowel have been used for urinary diversion. As a result, the available absorptive surface area of the bowel is reduced, and the incorporation of bowel segments into the urinary tract may have metabolic consequences. This is an area somewhat neglected in the literature. Metabolic complications are rare, but sub-clinical metabolic disturbances are quite common. Several studies have demonstrated that some of the absorbent and secreting properties of the bowel tissue are preserved after incorporation into the urinary tract. Hyperchloraemic metabolic acidosis can occur if ileal and/or colon segments are used, as well as malabsorption of vitamin B(12) and bile acid after the use of ileal segments. These metabolic effects are not as severe as may be suspected and can be prevented by prophylactic substitution. Secondary malignancies can develop as a long-term consequence of bladder augmentation. Using colonic segments, tumours are most likely to occur at the ureteral implantation site. To prevent metabolic complications, careful patient selection and meticulous and lifelong follow up, as well as prophylactic treatment, are mandatory. Endoscopy for early detection has been recommended, starting 10 years postoperatively for patients who underwent surgery for a benign condition.

Exstrophy bladder: Effect of sigmoid colocystoplasty on physical growth and bone mineral density

Background and Aims:

Introduction of intestinal tissue in the urinary tract results in numerous metabolic changes. This study investigates the effects of augmentation sigmoid colocystoplasty on the physical growth and bone mineralization in bladder exstrophy patients.

Materials and Methods:

Physical growth, serum biochemistry and bone mineral density were assessed pre and post augmentation in 34 of 54 patients who were treated by staged sigmoid colocystoplasty for classical bladder exstrophy during the period 1985–2007. Physical growth was determined by comparing the height and weight for age with standard growth charts. Serum biochemistry included calcium, phosphate and alkaline phosphatase levels. Bone mineral density (BMD) was determined at the femoral head using the dual energy X-ray absorptiometry (DEXA) scan at 15 ± 4.5 months after the augmentation. The DEXA scan findings were compared with 22 normal Indian children who served as controls and 18 unaugmented patients with bladder exstrophy. In 13 augmented patients, the DEXA scan could be repeated after an interval of six months.

Results:

The mean percentile height and weight were comparable in the pre and post-augmentation period with no statistically significant difference (P=0.135 for height and P=0.232 for weight). Biochemical parameters of bone metabolism also did not show any statistically significant changes after colocystoplasty. The BMD was 0.665 ± 0.062 g/cm² in the controls and 0.612 ± 0.10 g/cm² in the unaugmented bladder exstrophy patients. In the augmented patients, the BMD was 0.645 ± 0.175 g/cm² and six months later it was 0.657 ± 0.158 g/cm². These differences were not statistically significant.

Conclusions:

In our study, no significant effects on the physical growth and bone mineral metabolism were observed in exstrophy bladder patients following sigmoid colocystoplasty.

Urologic assessment of decreasing renal function

The discussion of renal failure as it relates to urology is largely a discussion of obstructive uropathy. Obstructive uropathy has been identified in multiple series to account for approximately 10% of all cases of renal failure. On a total population scale, autopsy series have shown the prevalence of hydronephrosis in 3% of men and women who are younger than 65 years and 6% of men older than 65 years. When benign prostatic hypertrophy and renal stone disease are considered, obstructive uropathy is also one of the most common indications for surgery. In this review, the different causes of obstructive renal insufficiency and management options available are discussed.

The updated EAU guidelines on muscle-invasive and metastatic bladder cancer

CONTEXT

New data regarding diagnosis and treatment of muscle-invasive and metastatic bladder cancer (MiM-BC) has emerged and led to an update of the European Association of Urology (EAU) guidelines for MiM-BC.

OBJECTIVE

To review the new EAU guidelines for MiM-BC.

EVIDENCE ACQUISITION

A comprehensive workup of the literature obtained from Medline, the Cochrane central register of systematic reviews, and reference lists in publications and review articles was developed and screened by a group of urologists, oncologists, and radiologist appointed by the EAU Guideline Committee. Previous recommendations based on the older literature on this subject were taken into account. Levels of evidence and grade of guideline recommendations were added, modified from the Oxford Centre for Evidence-based Medicine Levels of Evidence.

EVIDENCE SYNTHESIS

The diagnosis of muscle-invasive bladder cancer (BCa) is made by transurethral resection (TUR) and following histopathologic evaluation. Patients with confirmed muscle-invasive BCa should be staged by computed tomography (CT) scans of the chest, abdomen, and pelvis, if available. Adjuvant chemotherapy is currently only advised within clinical trials. Radical cystectomy (RC) is the treatment of choice for both sexes, and lymph node dissection should be an integral part of cystectomy. An orthotopic bladder substitute should be offered to both male and female patients lacking any contraindications, such as no tumour at the level of urethral dissection. Multimodality bladder-preserving treatment in localised disease is currently regarded only as an alternative in selected, well-informed, and compliant patients for whom cystectomy is not considered for clinical or personal reasons. An appropriate schedule for disease monitoring should be based on (1) natural timing of recurrence, (2) probability of disease recurrence, (3) functional deterioration at particular sites, and (4) consideration of treatment of a recurrence. In metastatic disease, the first-line treatment for patients fit enough to sustain cisplatin is cisplatin-containing combination chemotherapy. Presently, there is no standard second-line chemotherapy.

CONCLUSIONS

These EAU guidelines are a short, comprehensive overview of the updated guidelines of (MiM-BC) as recently published in the EAU guidelines and also available in the National Guideline Clearinghouse.

Principles of anaesthesia in urological surgery

Anaesthesia for urological surgery poses particular challenges for the anaesthetist related to the patient population and procedure type. The aim of this article is to cover the general principles of anaesthesia, with dedicated sections relevant to practising urological surgeons. This represents vast amounts of knowledge that cannot be covered in one article. We will focus upon preoperative preparation for surgery and anaesthesia, perioperative management including monitoring and analgesia, and postoperative management including fluid balance, critical care and recovery. Significant proportions of urological surgical patients have some degree of renal failure and this may be related to the surgery required. Anaesthetic care of patients with chronic renal impairment and transplant surgery will be covered in a future review.