Dosing considerations in the use of sodium phosphate bowel preparations for colonoscopy

Randomized clinical trial evaluating the effect of a visual educational leaflet on the preparation of colonoscopies in hospitalized patients

BACKGROUND

the safety and diagnostic accuracy of colonoscopies depends on the quality of colon cleansing. Several factors have been reported that affect the quality of bowel cleansing, hospitalization being one of them.

AIMS

the aim of the study was to investigate whether a visual educational leaflet improved the level of cleanliness achieved in hospitalized patients undergoing a colonoscopy and to identify predictors of a poor bowel preparation.

METHODS

a prospective, single-center, endoscopist-blinded, randomized controlled trial was performed. The intervention group was given a visual educational leaflet and both groups received four liters of polyethylene glycol solution. Demographic data, personal history, reason for admission and indication for colonoscopy, work shift during which the procedure was performed and endoscopy findings were collected. The Boston Bowel Preparation Scale (BBPS) was used to assess the bowel preparation.

RESULTS

one hundred and thirty-six patients were included in the study; 51.5% were male, with a mean age of 64.3 ± 17.6 years. The educational leaflet did not result in a difference in the total BBPS obtained between the standard group and the intervention group (7 [6-9] vs 6 [5.7-9]; p = 0.17). According to the multivariable analysis, the only factors associated with a poor bowel cleansing were heart disease (OR 3.37 [1.34-8.46]; p = 0.010) and colorectal cancer (OR 3.82 [1.26-11.61]; p = 0.018).

CONCLUSION

the use of a visual educational leaflet for the preparation of colonoscopies did not provide a significant improvement in hospitalized patients in our health area. Heart disease was identified as the only predictor of poor preparation for colonoscopy.

Colorectal Cancer Screening and Surveillance Colonoscopy in Older Adults

PURPOSE OF REVIEW

The purpose of this chapter is to highlight current recommendations regarding colorectal cancer (CRC) screening and post-polypectomy surveillance colonoscopy in older adults and to review the available literature in order to help inform decision-making in this age group.

RECENT FINDINGS

Age is a risk factor for CRC; however, older adults with a history of prior screening are at lower risk for CRC compared to those who have never been screened. Decision-making for CRC screening and post-polypectomy surveillance colonoscopy in older adults is complex and several factors including age, screening history, comorbidities, functional status, bowel preparation, prior experiences, preferences, and barriers need to be considered when weighing risks and benefits. Recent guidelines have started to incorporate life expectancy and prior screening history into their recommendations; however, how to incorporate these factors into actual clinical practice is less clear. There are limited data on the relative benefits of screening and surveillance in older adults and therefore, at this time, decision-making should be individualized and incorporate patient preferences in addition to medical factors.

Bowel preparation for colonoscopy may decrease the levels of testosterone in Korean men

Although colonoscopy is commonly conducted for medical check-ups in Korea, investigations for the influence of bowel preparation on various health conditions are insufficient. This cross-sectional study investigated whether bowel preparation has an influence on serum levels of testosterone. A total of 1114 men were divided into the bowel preparation group and control groups. The median total and free testosterone levels were significantly lower in the bowel preparation group (14.89 and 0.26 nmol/L, respectively) than in the control groups (15.72 and 0.28 nmol/L, respectively). The level of total testosterone significantly increased with age in the bowel preparation group (r = 0.103). The differences in the levels of total and free testosterone between the 2 groups were more prominent in younger men than in older men. In multivariate regression models, bowel preparation was independently associated with the levels of total and free testosterone. In these models, the interaction between age and bowel preparation was significant for the levels of total and free testosterone. In conclusion, bowel preparation may independently decrease the serum levels of total and free testosterone. The decline in testosterone was more evident in younger men than in older men.

Optimizing bowel preparation for colonoscopy: a guide to enhance quality of visualization

Colonoscopy is an important screening and therapeutic modality for colorectal cancer. Unlike other screening tests, colonoscopy is dependent on pre-procedure bowel preparation. If the bowel preparation is poor, significant pathology may be missed. Many factors are known to improve bowel preparation. This review will highlight those factors that may optimize the bowel preparation, including choice of bowel preparation, grading or scoring of the bowel preparation, special factors that influence preparation, and diet prior to colonoscopy that affects bowel preparation. The aim of the review is to offer suggestions and guide endoscopists on how to optimize the bowel preparation for the patients undergoing colonoscopy.

Optimizing bowel cleansing for colonoscopy

Adequate bowel cleansing is essential for complete examination of the colon mucosa during colonoscopy. Suboptimal bowel preparation has potential adverse consequences, such as missed pathologic abnormalities, the need for repeated procedures, and increased procedure-related complications. Several factors can predict individuals at increased risk for inadequate bowel preparation. If predictors of inadequate bowel preparation are identified, then education should be intensified and a more aggressive bowel regimen recommended. On completion of this article, you should be able to (1) define the frequency of inadequate colon preparations, (2) identify predictors of poor bowel preparation, and (3) use a more aggressive bowel regimen when clinically indicated.

Evaluation of intestinal phosphate binding to improve the safety profile of oral sodium phosphate bowel cleansing

Prior to colonoscopy, bowel cleansing is performed for which frequently oral sodium phosphate (OSP) is used. OSP results in significant hyperphosphatemia and cases of acute kidney injury (AKI) referred to as acute phosphate nephropathy (APN; characterized by nephrocalcinosis) are reported after OSP use, which led to a US-FDA warning. To improve the safety profile of OSP, it was evaluated whether the side-effects of OSP could be prevented with intestinal phosphate binders. Hereto a Wistar rat model of APN was developed. OSP administration (2 times 1.2 g phosphate by gavage) with a 12h time interval induced bowel cleansing (severe diarrhea) and significant hyperphosphatemia (21.79 ± 5.07 mg/dl 6h after the second OSP dose versus 8.44 ± 0.97 mg/dl at baseline). Concomitantly, serum PTH levels increased fivefold and FGF-23 levels showed a threefold increase, while serum calcium levels significantly decreased from 11.29 ± 0.53 mg/dl at baseline to 8.68 ± 0.79 mg/dl after OSP. OSP administration induced weaker NaPi-2a staining along the apical proximal tubular membrane. APN was induced: serum creatinine increased (1.5 times baseline) and nephrocalcinosis developed (increased renal calcium and phosphate content and calcium phosphate deposits on Von Kossa stained kidney sections). Intestinal phosphate binding (lanthanum carbonate or aluminum hydroxide) was not able to attenuate the OSP induced side-effects. In conclusion, a clinically relevant rat model of APN was developed. Animals showed increased serum phosphate levels similar to those reported in humans and developed APN. No evidence was found for an improved safety profile of OSP by using intestinal phosphate binders.

Endoscopy in the elderly: risks, benefits, and yield of common endoscopic procedures

There has been limited research examining the risks, benefits, and use of common endoscopic procedures in the elderly. Furthermore, gastroenterology training programs do not routinely incorporate elderly concerns when dealing with common gastrointestinal issues. There exists a broad array of endoscopic procedures with varying inherent risks that must be weighed with each elderly patient in mind. This article discusses the benefits and drawbacks of the most common procedures and indications for endoscopy including upper endoscopy, colonoscopy, endoscopic retrograde cholangiopancreatography, endoscopic ultrasound, percutaneous endoscopic gastrostomy, and deep enteroscopy.

Colonoscopy preparation-induced disorders in renal function and electrolytes

Colonoscopy and flexible sigmoidoscopy are commonly used mainly for colon cancer screening and detection, but also in several other situations such as inflammatory bowel disease (for diagnosis and follow up) and gastrointestinal hemorrhage. Bowel cleansing preparations mainly include polyethylene glycol and oral sodium phosphate solutions, with the later being most frequently used due to better toleration from patients. Despite their favourable safety profile these agents have been associated with renal function deterioration and electrolyte disorders, some of which were serious or even fatal. The present paper discusses the complications associated with colonoscopy preparation agents.

The modern bowel preparation in colonoscopy

Adequate bowel preparation is essential for optimal colonoscopy. Suboptimal bowel preparation occurs in 25% to 40% of cases and is associated with canceled procedures, prolonged procedure time, incomplete examination, increased cost, and missed pathology. There are several effective formulations for colon cleansing with a good safety profile. Split dosing should be implemented whenever possible in an effort to enhance tolerance and adherence, and improve mucosal visibility and overall quality of the examination. In this review, modern bowel preparations are discussed including their mechanism of action, mode of use, safety, and how to optimize outcomes.

Colorectal cancer screening and surveillance in the elderly patient

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in the United States. Older age is associated with a rise in colorectal cancer and adenomas, necessitating the need for CRC screening in older patients. However, decisions about CRC screening and surveillance in older adults are often difficult and challenging. The decision requires an individualized assessment that incorporates factors unique to performing colonoscopy in older adults in order to weigh the risks and benefits for each patient according to their overall health and preferences. This review addresses the factors unique to colorectal cancer and performing colonoscopy in older adults that are relevant in weighing the risks and benefits of screening and surveillance in this population.

Intermediate bioelectrolyte changes after phospho-soda or polyethylene glycol precolonoscopic laxatives in a population undergoing health examinations

BACKGROUND

Colonoscopy is a common procedure for diagnosing and screening colon cancer and other bowel-related diseases. Many studies have pointed out that using phospho-soda as a bowel preparation can cause obvious electrolyte abnormalities or acute kidney injury. Nonetheless, there are few studies related to its prevalence and risk factors in the population undergoing health examinations. Our aim was to compare the biochemical and electrolyte changes after using two commonly used bowel preparation regimens in this population.

METHODS

In this retrospective study, we collected data about participants who, before a screening colonoscopy, used oral phospho-soda laxatives in 2006, and those who used polyethylene glycol-based laxatives in 2005. Several serum biochemical and electrolyte profiles were compared between the two groups. Additional risk factors of hyperphosphatemia, a well-known side effect of phospho-soda, were also derived.

RESULTS

We enrolled a total of 2270 participants (1321 in 2005; 1449 in 2006). The basic demographic data of the two groups were not statistically different. Nonetheless, between the two groups, some serum biochemical and electrolytic data differed significantly: in those using oral phospho-soda laxatives, we found a higher prevalence of hyperuricemia, hypocalcemia, hypokalemia, hypernatremia and hyperphosphatemia. Further analyses showed that using oral phospho-soda laxatives was a risk factor for hyperphosphatemia; conversely, being male was a protective factor.

CONCLUSION

Oral phospho-soda laxatives indeed influence the biochemical and electrolyte profiles of persons undergoing health examinations. One should be careful when interpreting bioelectrolytic data while using phospho-soda as a bowel preparation.

Development and validation of a novel patient educational booklet to enhance colonoscopy preparation

OBJECTIVES

The success of colonoscopy depends on high-quality bowel preparation by patients; yet inadequate preparation is common. We developed and tested an educational booklet to improve bowel preparation quality.

METHODS

We conducted patient cognitive interviews to identify knowledge and belief barriers to colonoscopy preparation. We used these interviews to create an educational booklet to enhance preparatory behaviors. We then prospectively randomized patients scheduled for outpatient colonoscopy at a VA Medical Center to receive usual instructions vs. the booklet before colonoscopy. Patients in both groups received standard pharmacy instructions for single-dose bowel preparation; the protocol did not specify which purgatives to prescribe. The primary outcome was preparation quality based on blinded ratings using the validated Ottawa score. We performed bivariate analyses to compare mean scores between groups using a t-test, and logistic regression to measure the booklet effect on preparation quality, adjusting for potential confounders.

RESULTS

A total of 436 patients were randomized between arms. In an intention-to-treat analysis of the primary outcome, mean Ottawa scores were superior in patients allocated to booklet vs. controls (P=0.03). An intention-to-treat analysis of the secondary outcome revealed a "good" preparation in 68 vs. 46% of booklet and control patients, respectively (P=0.054). In a per-protocol analysis limited to patients who actually received the booklet, preparation was good in 76 vs. 46% patients, respectively (P<0.00001). Regression analysis revealed that booklet receipt increased the odds of good preparation by 3.7 times (95% confidence interval=2.3-5.8).

CONCLUSIONS

Provision of a novel educational booklet considerably improves preparation quality in patients receiving single-dose purgatives. The effect of the booklet on split-dose purgatives remains untested and will be evaluated in future research.

Magnesium citrate with a single dose of sodium phosphate for colonoscopy bowel preparation

AIM

To evaluate the efficacy and acceptability of magnesium citrate and a single dose of oral sodium phosphate (45 mL) solution for morning colonoscopy bowel preparation.

METHODS

A total of 159 patients were randomly assigned to receive two split doses of 90 mg of sodium phosphate (Group I, n = 79) or magnesium citrate (250 mL, the day before the procedure) followed by 45 mL of sodium phosphate (the day of procedure, Group II, n = 80). The quality of bowel cleansing and the acceptability of each regimen were compared, including the satisfaction, taste, willing to repeat and adverse effects of each regimen.

RESULTS

The quality of bowel cleansing of Group II was as good as that of Group I (An Aronchick scale score of good or excellent: 70.9% vs 81.0%, respectively, P = 0.34; the Ottawa system score: 4.4 ± 2.6 vs 3.8 ± 3.0, respectively, P = 0.76). There was no statistically significant difference between both groups with regard to acceptability, including the satisfaction, taste and willingness to repeat the regimen. A significantly greater number of older patients (over 65 years old) in Group II graded the overall satisfaction as satisfactory (48.1% vs 78.1%, respectively; Group I vs Group II, P = 0.01). There were no significant adverse reactions.

CONCLUSION

Magnesium citrate and a single dose of sodium phosphate was as effective and tolerable as the conventional sodium phosphate regimen and is a satisfactory option.

Mechanism of action and toxicities of purgatives used for colonoscopy preparation

IMPORTANCE OF THE FIELD

In developed countries, colonoscopy volume has increased dramatically over the past 15 years and is the principle method used to screen for colon cancer. Preparations used for colon cleaning have evolved over the past 30 years. Some preparations have been shown to be unsafe and are now used on a limited basis. There has been progress on limiting the volume required and on taste improvement.

AREAS COVERED IN THIS REVIEW

This review provides an account of preparations used from 1980 when PEG-based preparations became widely available, until the present day. The review highlights their mechanism of action and principle toxicities. The handling of solutes and solute-free fluid by the colon is also reviewed.

WHAT THE READER WILL GAIN

The reader will gain a perspective on the factors considered in developing colonic purgatives and the rationale for choosing selected preparations based on patient factors such as age, co-morbidities and concomitant medications.

TAKE HOME MESSAGE

Although generally safe and effective, colonic purgatives have both acute and permanent toxicities. The safest preparations utilize PEG combined with a balanced electrolyte solution. Limitations of this preparation center on the volume required and poor taste. Alternative formulations are now available; however, those using sodium phosphate have fallen out of favor due to a risk of renal toxicity.

Split-dose bowel preparation for colonoscopy and residual gastric fluid volume: an observational study

BACKGROUND

Split-dose bowel preparations for colonoscopy are more effective and better tolerated than preparations given entirely the day or evening before the procedure; however, some resistance to split-dose preparation stems from concerns about an increased risk of aspiration with same-day preparation.

OBJECTIVE

We sought to evaluate residual gastric volumes in patients after split-dose bowel preparations.

DESIGN

Prospective measurement of residual gastric volumes in patients undergoing same-day EGD and colonoscopy after split-dose bowel preparations, patients undergoing EGD alone, or patients undergoing EGD and colonoscopy after bowel preparation given entirely the evening before the procedure.

SETTING

Tertiary care hospital-based endoscopy unit.

PATIENTS

This study involved 712 patients, including 254 in the split-dose bowel preparation group, 411 in the EGD-only group, and 47 in the evening-before-procedure bowel preparation group.

INTERVENTION

Measurement of residual gastric volume before endoscopic procedures.

MAIN OUTCOME MEASUREMENTS

Residual gastric volume.

RESULTS

The mean residual gastric volume in patients receiving split-dose bowel preparation (19.7 mL) was higher than in patients undergoing EGD alone (14.6 mL) but not different from that in patients receiving bowel preparation the evening before the procedure (20.2 mL). Within the split-dose preparation group, there was no association between the interval from last actual fluid ingestion and procedure start time and the residual gastric volume. The range of residual gastric volumes between study arms was similar.

LIMITATIONS

Nonrandomized study. The number of inpatients undergoing split-dose bowel preparation was small.

CONCLUSION

These data support the safety of split-dose bowel preparation for outpatients undergoing colonoscopy.

Bowel preparation for pediatric colonoscopy procedures

Colonoscopy is a routinely performed procedure in children and adolescents. Proper visualization of the intestinal mucosa, completion of the procedure, including examination of the terminal ileum, detection of pathological lesions, and therapeutic maneuvers, all are highly dependent on the quality of the bowel preparation. A significant proportion of patients, in some reports up to one third, are inadequately prepared for the examination, which leads to extended procedure time, incomplete examination, or need for repeat procedure. Aside from efficacy and safety, the most important aspects of colon preparation in pediatrics are ease of administration, palatability, dietary restriction, and minimization of disruption of daily routine. An ideal preparation does not exist and a wide variety of regimens are being used. Several of these have been investigated in pediatric clinical trials. This article reviews the published literature with an emphasis on the most commonly used agents, their mechanism of action, efficacy and ease of use, and safety.

Efficacy of morning-only compared with split-dose polyethylene glycol electrolyte solution for afternoon colonoscopy: a randomized controlled single-blind study

OBJECTIVES

Administering a purgative close to the time of colonoscopy is optimal for cleansing. The aim of this study was to compare the efficacy and tolerability of morning-only (AM-only) polyethylene glycol electrolyte solution (PEG-ELS) to split-dose (PM/AM) PEG-ELS for afternoon colonoscopy.

METHODS

This was a single-center, prospective, randomized, investigator-blinded, non-inferiority study comparing AM-only to PM/AM PEG-ELS for afternoon outpatient colonoscopy. The primary end point was whole colon prep adequacy. Tolerance and polyp detection were secondary outcomes.

RESULTS

Overall, 125 patients were randomized and 9 withdrew without taking any prep. Of 116 analyzed, 62 received AM-only prep and 54 received PM/AM prep. The whole colon prep was adequate in 92% in the AM-only group vs. 94% in the PM/AM group (95% lower confidence limit, LCL, for the difference=-11.3%, non-inferiority P=0.013), whereas the right colon prep was adequate in 93 and 92%, respectively (95% LCL=-7.8%, non-inferiority P=0.003). Polyp detection was greater, and not inferior, in the AM-only group (mean=1.57 vs. 0.94 polyps/patient, non-inferiority P=0.007). The overall incidence of adverse events was not significantly different between the two groups (P=0.273), but the AM-only group had lower incidence of abdominal pain (P=0.024). The AM-only group also had better sleep quality (P=0.007) and less interference with the previous workday (P=0.019).

CONCLUSIONS

AM-only and PM/AM PEG-ELS are clinically equivalent with respect to cleansing efficacy and polyp detection. AM-only prep was associated with a lower incidence of abdominal pain, superior sleep quality, and less interference with workday before colonoscopy.

Sudden hypotensive syncope and significant iatrogenic maxillofacial trauma following administration of oral sodium phosphate purgative solution

Oral sodium phosphate (NaP) solution is used globally as a bowel preparation for colonoscopy, surgery and medical-imaging (Balaban 2008). We present a case of a patient who suffered sudden hypotensive syncope and iatrogenic mandibular fractures within an hour of ingesting a NaP solution. We discuss the uses of these medicines and highlight the need to warn patients of possible adverse side effects to avoid patient harm and subsequent litigation.

Endoscopy in the elderly: a review of the efficacy and safety of colonoscopy, esophagogastroduodenoscopy, and endoscopic retrograde cholangiopancreatography

Gastrointestinal endoscopy including colonoscopy, esophagogastroduodenoscopy, and endoscopic retrograde cholangiopancreatography (ERCP) are safe and efficacious in elderly patients. Screening colonoscopies have little efficacy in patients over 80 years. Colonoscopies performed for bleeding or iron-deficiency anemia have a higher yield in elderly patients. Colonic preparations were well tolerated and colonoscopic success rates are high in elderly patients. However, poor colonic preparation is more likely in these patients. Esophagogastroduodenoscopy is a high-yield procedure with no significant increase in adverse events in patients over 80 years with symptoms including dyspepsia and dysphagia. ERCP in the elderly carries a high degree of success with low complication rates. Elderly patients undergoing ERCP carry similar risks of bleeding and perforation and a lower risk of pancreatitis compared with younger patients. Advanced age should not be regarded as an absolute contraindication to any gastrointestinal endoscopy procedure.

Hyperphosphatemia after sodium phosphate laxatives in low risk patients: prospective study

AIM

To establish the frequency of hyperphosphatemia following the administration of sodium phosphate laxatives in low-risk patients.

METHODS

One hundred consecutive ASA I-II individuals aged 35-74 years, who were undergoing colonic cleansing with oral sodium phosphate (OSP) before colonoscopy were recruited for this prospective study.

EXCLUSION CRITERIA

congestive heart failure, chronic kidney disease, diabetes, liver cirrhosis, intestinal obstruction, decreased bowel motility, increased bowel permeability, and hyperparathyroidism. The day before colonoscopy, all the participants entered a 24-h period of diet that consisted of 4 L of clear fluids with sugar or honey and 90 mL (60 g) of OSP in two 45-mL doses, 5 h apart. Serum phosphate was measured before and after the administration of the laxative.

RESULTS

The main demographic data (mean +/- SD) were: age, 58.9 +/- 8.4 years; height, 163.8 +/- 8.6 cm; weight, 71 +/- 13 kg; body mass index, 26 +/- 4; women, 66%. Serum phosphate increased from 3.74 +/- 0.56 to 5.58 +/- 1.1 mg/dL, which surpassed the normal value (2.5-4.5 mg/dL) in 87% of the patients. The highest serum phosphate was 9.6 mg/dL. Urea and creatinine remained within normal limits. Post-treatment OSP serum phosphate concentration correlated inversely with glomerular filtration rate (P < 0.007, R(2) = 0.0755), total body water (P < 0.001, R(2) = 0.156) and weight (P < 0.013, R(2) = 0.0635).

CONCLUSION

In low-risk, well-hydrated patients, the standard dose of OSP-laxative-induced hyperphosphatemia is related to body weight.

Increased serum phosphate levels and calcium fluxes are seen in smaller individuals after a single dose of sodium phosphate colon cleansing solution: a pharmacokinetic analysis

BACKGROUND

Sodium phosphate containing colonoscopy preparations may cause electrolyte disturbances and calcium-phosphate nephropathy. Decreased body weight is an unexplored risk factor for complications with sodium phosphate ingestion.

AIM

To perform a pharmacokinetic analysis of a single dose of Fleet Phospho-Soda in smaller and larger individuals.

METHODS

Seven subjects weighing <55 kg (Group I) and six weighing >100 kg (Group II) consumed 45 mL Fleet Phospho-Soda. Serum electrolytes were measured. Hydration was closely maintained by monitoring weight, fluid intake and total body water.

RESULTS

Marked increases in serum phosphate were seen in Group I compared to Group II. For example, mean serum phosphate at 120 min was 7.8 +/- 0.5 mg/dL in Group I and 5.1 +/- 0.8 mg/dL in Group II (P < 0.001). Normalized area under the phosphate vs. time curve for Group I was 1120 +/- 190 mg/dL*min and 685 +/- 136 mg/dL*min for Group II (P < 0.001). Twelve-hour urine calcium was lower in Group I (16.4 +/- 7.6 mg) than in Group II (39.2 +/- 7.8 mg, P < 0.001).

CONCLUSIONS

Increased serum phosphate occurs in smaller individuals after ingestion of sodium phosphate preparations, even with strict attention to fluid intake. Smaller body weight poses a potential risk for calcium-phosphate nephropathy.

Colon cleansing before colonoscopy: does oral sodium phosphate solution still make sense?

Oral sodium phosphate (NaP) solution has been withdrawn from the market in the United States but remains available for over-the-counter purchase for bowel preparation for colonoscopy in Canada. The present review summarizes recent data regarding the renal toxicity of oral NaP as well as its efficacy and tolerability relative to other preparations. Given the availability of effective alternatives to NaP solution, its use for colonoscopy preparation in Canada should be limited. Candidate patients for oral NaP solution should be assessed for eligibility and preparation instructions should adhere to the current recommendations for maximizing the safety of oral NaP.

Bowel preparations for colonoscopy: a review

PURPOSE

The mechanisms of action, clinical efficacy, tolerability, and safety of two major classes of bowel purgatives, poly-ethylene glycol- electrolyte lavage solutions (PEG-ELSs) and sodium phosphate preparations, are reviewed.

SUMMARY

PEG-ELSs are osmotically balanced preparations that promote bowel cleansing through the ingestion of nonabsorbable fluid. Sodium phosphate preparations are hyperosmotic purgatives that promote bowel cleansing by osmotically drawing fluid into the bowel lumen for evacuation. Studies suggest that 2-L PEG-ELS regimens are generally as effective as and more tolerable than full-volume PEG-ELS preparations. Studies have also found that sodium phosphate tablets may provide a more tolerable alternative to PEG-ELS regimens and traditional sodium phosphate products without compromising bowel cleansing efficacy. Proper renal function plays a particularly important role in avoiding potential safety issues related to sodium phosphate-induced shifts in the fluid and electrolyte balance. Preventing dehydration in patients undergoing bowel preparation can prevent severe adverse events, regardless of the purgative administered. Optimizing the process of bowel preparation involves administering proper purgative choices in appropriate patient populations. Moreover, patient education and compliance with preparation instructions, including correct dosing and adequate hydration, may reduce the risk of adverse events and serious complications.

CONCLUSION

Although next-generation PEG-ELS and sodium phosphate products are well tolerated and preferred by patients over traditional bowel preparation regimens, safety issues remain a concern for both purgative classes. Sodium phosphate preparations are generally more effective and better tolerated than PEG-ELS formulations but should be administered with caution in patients with preexisting or at an increased risk for electrolyte disturbances.

Pico-salax plus two-day bisacodyl is superior to pico-salax alone or oral sodium phosphate for colon cleansing before colonoscopy

OBJECTIVES

This study examined whether Pico-Salax alone or Pico-Salax plus bisacodyl tablets for two nights before colonoscopy afford superior efficacy, patient tolerance, and safety compared with oral sodium phosphate.

METHODS

Patients undergoing outpatient colonoscopy were randomized to receive either Pico-Salax at 5 and 10 PM the night before colonoscopy plus bisacodyl 10 mg at 5 PM in the two earlier evenings (n=105), Pico-Salax alone at 5 and 10 PM the night before colonoscopy (n=109), or oral sodium phosphate at 5 and 10 PM the night (n=101) before colonoscopy. All groups were encouraged to drink 3-4 l of Gatorade or other clear fluids the night before the colonoscopy.

RESULTS

Global scoring of cleansing efficacy using the Ottawa scale did not reveal differences among groups, but Pico-Salax plus bisacodyl was superior in cleansing the right colon compared with the other regimens (P=0.003), providing almost 50% improvement over oral sodium phosphate. Patient tolerance of Pico-Salax plus bisacodyl did not differ from Pico-Salax alone but was much better than oral sodium phosphate (P<0.0001). Hemodynamic and biochemical monitoring of patients on Pico-Salax plus bisacodyl suggests this regimen has a very strong safety profile. It does not differ from Pico-Salax alone, which lacks the hyperphosphatemia and hypocalcemia associated with oral sodium phosphate.

CONCLUSIONS

Together, these data suggest that Pico-Salax plus bisacodyl provides enhanced colon cleansing in the right colon compared with Pico-Salax alone or oral sodium phosphate, but this finding does not compromise the much greater tolerability or the safety profile of Pico-Salax alone.

Duration of the interval between the completion of bowel preparation and the start of colonoscopy predicts bowel-preparation quality

BACKGROUND

Recent studies suggest that colonoscopies done in the morning have better-quality bowel preparations than those done in the afternoon.

OBJECTIVE

We aimed to determine how the duration of the interval between the end of the preparation and the start of the colonoscopy affects preparation quality.

DESIGN

We prospectively studied consecutive outpatients who had colonoscopies performed at our hospital within a 3-month period. The time of day when the colonoscopy started and the time interval from the last dose of preparation agent to the start of the colonoscopy were recorded. The endoscopist graded the quality of the preparation in the right side of the colon by using a 5-point visual scale.

PATIENTS

We studied 378 patients (96% men, mean age 62.2 years) who received preparations of polyethylene glycol electrolyte-based (PEG) and sodium phosphate (SP) solution (71%), oral PEG and magnesium citrate (23%), or SP alone (6%).

RESULTS

Compared with patients whose preparations were graded as 2/3/4 (fair/poor/inadequate), those whose preparations were graded as 0/1 (excellent/good) had a significantly shorter interval between the time of the last preparation agent dose and the start of the colonoscopy (P = .013).

LIMITATIONS

We used a nonvalidated scale to assess the quality of bowel preparation.

CONCLUSIONS

Bowel-preparation quality varies inversely with the duration of the interval between the last dose of the bowel-preparation agent and the start of colonoscopy. This interval appears to be a better predictor of bowel-preparation quality than the time of day when colonoscopy is performed.

Comparação entre as soluções orais de manitol a 10% e bifosfato de sódio no preparo mecânico do cólon

OBJETIVO: Comparar o uso das soluções orais de manitol a 10% e de bifosfato de sódio no preparo mecânico do cólon quanto a qualidade da limpeza, a tolerabilidade e as alterações hidroeletrolíticas e da osmolaridade plasmática. MÉTODO: Foram analisados 60 pacientes de modo randomizado, duplo-cego e prospectivo, com indicação de colonoscopia. A qualidade da limpeza intestinal foi analisada pelo examinador através da classificação de Beck. A tolerabilidade à ingestão baseou-se na pesquisa do gosto, presença ou não de desconforto, aparecimento de efeitos adversos e a quantidade da solução ingerida. Foram dosados o sódio, potássio, cálcio, magnésio, fósforo, uréia, creatinina, glicose, hematócrito, hemoglobina e calculado a osmolaridade plasmática, antes e após a ingestão da solução oral de preparo inestinal. RESULTADOS: Ambas as soluções atingiram qualidade de preparo classificado como bom ou superior em mais de 80% dos pacientes. O uso do bifosfato de sódio determinou menor desconforto e melhor tolerância, apesar de não ter sido superior ao manitol quanto à análise do gosto e presença de efeitos adversos. O bifosfato induziu ao aumento e o manitol a uma redução da osmolaridade, reflexo do que ocorreu com o sódio plasmático nos dois grupos respectivamente. O bifosfato ainda determinou alteração significativa dos níveis séricos de fósforo, cálcio, magnésio e potássio, sem repercussões clínicas. CONCLUSÃO: Ambos os tipos de preparo intestinal determinaram qualidade de limpeza adequada. O bifosfato de sódio, apesar de melhor tolerado, determina maior quantidade de alterações hidroeletrolíticas.

Is bowel preparation before colonoscopy a risky business for the kidney?

Acute phosphate nephropathy after bowel preparation with oral sodium phosphate (OSP) for colonoscopy has emerged as an important clinical entity. In 2004, five cases of nephrocalcinosis and irreversible renal failure after bowel preparation with OSP were reported. More recently, several retrospective studies have shown that the incidence of acute kidney injury after OSP use is in the range of 1-4%, similar to the incidence of contrast nephropathy in the general population. The degree of renal failure is not generally as severe as in the first reported cases, but irreversible damage can still occur. Millions of people worldwide undergo screening colonoscopies for colon and rectal cancer after the age of 50, so careful patient selection and monitoring for possible complications is essential when OSP is used. In addition to educating patients about the possibility of renal damage, physicians should routinely watch for considerable weight loss during bowel preparation and correct the fluid deficit as needed. Carrying out a renal function panel, which includes serum phosphorus level, is prudent after colonoscopy. Alternative bowel cleansing agents are needed because calcium phosphate precipitation is inevitable after OSP use even in the normal kidney.

Adverse renal and metabolic effects associated with oral sodium phosphate bowel preparation

Colorectal cancer can be prevented by the removal of adenomatous polyps during screening colonoscopy, but adequate bowel preparation is required. Oral sodium phosphate (OSP), an effective bowel purgative, is available over the counter and requires a substantially lower volume than polyethylene glycol-based preparative agents. Accumulating reports implicate OSP in electrolyte disturbances as well as acute kidney injury (AKI) in a syndrome termed phosphate nephropathy (a form of nephrocalcinosis). Despite published case reports and case series, the actual incidence, risk factors, and natural history of phosphate nephropathy remain largely undefined. Several recent observational studies have provided new information on these important issues while supporting a link between OSP and acute phosphate nephropathy as well as the development of chronic kidney disease in elderly patients, many of whom had a normal serum creatinine at the time of OSP ingestion. This review summarizes current knowledge about the renal complications of OSP, risk factors for its development, and the pathophysiology of acute and chronic kidney damage in nephrocalcinosis.