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Split-dose sodium picosulfate–magnesium citrate colonoscopy preparation achieves lower residual gastric volume with higher cleansing effectiveness than a previous-day regimen

Gastrointest Endosc. 2016;83(3):566-73

Background and Aims

It is known that sodium picosulfate–magnesium citrate (SPMC) bowel preparations are effective, well tolerated and safe, and that split-dosing is more effective for colon cleansing than previous-day regimens. Anesthetic guidelines consider that residual gastric fluid is independent of clear liquid fasting times. However, reluctance to use split-dosing persists. This may be due to limited data on residual gastric fluid volumes (RGFVs) and split-dosing bowel preparations, and that these may not be perceived as standard clear liquids. Furthermore, no studies are available on RGFV/residual gastric fluid pH (RGFpH) and SPMC. We aimed to evaluate the cleansing effectiveness and the RGFV/RGFpH achieved after an SPMC split-dosing regimen compared with a SPMC previous-day regimen.


This was a single-center observational study. A total of 328 outpatients scheduled for simultaneous EGD and colonoscopy and following a split-dosing or previous-day regimen of SPMC were included. We prospectively measured colon cleanliness by using the Ottawa Bowel Preparation Scale, RGFV, and RGFpH.


Ottawa Bowel Preparation Scale scores for overall, right, mid-colon, and colon fluid were significantly better in the split-dosing group. In the split-dosing group, the 3- to 4-hour fasting time consistently achieved the best cleansing quality. RGFV was significantly lower in the split-dosing group (11.09 vs 18.62, P < .001). No significant differences in RGFpH were detected.


Split-dosing SPMC provides higher colon cleansing quality with lower RGFVs than previous-day SPMC regimens. SPMC in split-dosing acts exactly as a standard clear liquid acts, and thus anesthetic guidelines on this issue may be applied with no concerns.

Abbreviations: FT - fasting time, NaP - sodium phosphate, OBPS - Ottawa Bowel Preparation Scale, PEG - polyethylene glycol, PPI - proton pump inhibitor, RGFpH - residual gastric fluid pH, RGFV - residual gastric fluid volume, SPMC - sodium picosulfate–magnesium citrate.


Colonoscopy is currently the criterion standard test for both colorectal cancer screening and investigation of both colon and terminal ileum diseases.1, 2, and 3 To achieve a successful examination of the entire colon mucosa, the effectiveness and tolerability of bowel preparations are essential.4 and 5 Inadequate colon preparation results in longer procedures6; decreased cecal intubation rate6; decreased detection of small, large, and flat polyps6, 7, and 8; and increased patient discomfort and costs,4 and 9 whereas large-volume or unpalatable agents are poorly tolerated and decrease patient adherence to recommendations (and therefore efficacy) and willingness to repeat the procedure.4, 5, 10, and 11

To increase efficacy and compliance, new laxative agents and different doses and regimens are being developed and compared. Citrafleet (Laboratorios Casen Recordati SLU, Utebo-Zaragoza, Spain) is a small-volume preparation based on oral sodium picosulfate and magnesium citrate (SPMC) with a combined osmotic and stimulant effect. SPMC has been widely used in Europe for many years and is considered an effective, well-tolerated, and safe bowel preparation for colonoscopy.11, 12, 13, 14, and 15 On the other hand, there is extensive evidence that split-dosing regimens, which consist of the administration of at least 1 portion of the preparation on the evening before the procedure and the rest on the morning of the examination, are more effective for colon cleansing2, 16, 17, and 18 and adenoma detection19 than previous-day regimens, when either polyethylene glycol (PEG) or sodium phosphate (NaP) are prescribed. Recent studies have also demonstrated that split-dosing is more effective than previous-day preparations when SPMC is used.20 and 21 Based on this evidence, split-dosing is recommended as the standard preparation by the American College of Gastroenterology1 and different guidelines.5 and 22 Specifically, a SPMC split regimen is recommended by the European Society of Gastroenterology as a valid alternative to a standard 4-L PEG split regimen.23

However, there is still some reluctance to use split-dosing regimens in daily clinical practice. The main reason seems to be the speculation that a shortened fasting period before colonoscopy sedation would imply higher amounts of residual gastric liquid and consequently a higher risk of pulmonary aspiration. To date, we have no evidence of increased risk of pulmonary aspiration when a split-dosing regimen is prescribed; however, data are scarce and studies rely on surrogate indicators of aspiration risk, such as gastric volume and pH. These studies have demonstrated that residual gastric fluid and pH are independent of the clear liquids fasting period,24, 25, 26, and 27 and thus, most anesthetic guidelines support a clear liquids fasting period of 2 to 3 hours before elective procedures requiring general anesthesia, regional anesthesia, or sedation/analgesia.28 and 29 If some resistance to using split-dosing regimens still persists, this may be because clinicians do not perceive colon preparations as a standard clear liquid. In fact, the previously mentioned studies explicitly refer to limited volumes of water, coffee, tea, isotonic, or carbohydrate drinks and clear juices.26 However, none specifically mention bowel preparations. Furthermore, conflicting results exist on whether the high volume and particular osmotic characteristics of these preparations may alter gastric emptying.30 and 31

The only previous published study addressing this issue demonstrated that residual gastric volume of patients prepared with split-dosing regimens of PEG or NaP was similar to those prepared with previous-day regimens by using the same agents.32 However, no similar studies have been carried out with other common agents such as SPMC, and we do not know how the split-dosing regimen of a bowel preparation could modify residual gastric fluid pH.

The aim of the study is to assess the effectiveness and safety profile of a split-dosing regimen with SPMC, comparing colon-cleansing efficacy, residual gastric fluid volume (RGFV), and residual gastric fluid pH (RGFpH) between an SPMC split-dosing regimen and an SPMC previous-day bowel preparation.


Between October 2012 and May 2014, we prospectively recruited consecutive patients 18 to 80 years of age scheduled for an elective outpatient EGD and colonoscopy on the same day at our hospital (Clínica Universidad de Navarra, Pamplona, Spain). Exclusion criteria included suspected or known acute colon disease, ileus, bowel obstruction or pseudo-obstruction, known gastroparesis, gastric outlet obstruction, or known hiatal hernia larger than 4 cm. Patients with a history of upper GI surgery that could interfere with gastric emptying or bowel motility (such as an intestinal bypass or a gastric or bowel resection) or any colorectal surgery (excluding appendectomy or hemorrhoid surgery) were excluded. Patients with renal insufficiency (defined as a creatinine level higher than normal range for age and sex), congestive heart failure, uncontrolled hypertension, American Society of Anesthesiologists class IV, pregnant or lactating women, or those patients unable to comprehend the nature of the study or give their consent were also excluded. The study was approved by the local and regional ethics committee (EO 10/2012) and by the institutional review board on April 2012 (ICT-PIC-2012-01). Written informed consent was obtained from all participants.

At the time of acceptance into the study, patients were interviewed by a dedicated nurse who collected their demographic data and baseline characteristics and assigned patients to a previous-day bowel preparation group or the split-dosing group based on the hour of the first medical visit appointment. Patients who visited from 9:00 am to 12:00 pm were assigned to the split-dosing group, whereas those who visited from 12:00 pm to 3:00 pm received instructions for a previous-day schedule. Opioids and oral iron were discontinued if possible at the time of the medical visit or at least 48 hours before the procedure, as is usually done in our daily medical practice. Benzodiazepines, tricyclic antidepressants, prokinetics, and proton pump inhibitors (PPIs) were maintained as prescribed until the initiation of the preparation. The nurse carefully explained the instructions, indicating the need to observe a low-fiber diet 2 days before the procedures and giving oral and written information about the forbidden foods and the importance of adequate colon cleansing for the purpose of the procedure, as is usually done in our daily clinical practice. All patients were instructed to have a light low-fiber breakfast and lunch the day before the procedure. Citrafleet consists of 2 sachets, each containing 10 mg of sodium picosulfate, 3.5 g of light magnesium oxide, and 10.97 g of anhydrous citric acid. Patients in each group were instructed to follow the directions shown in Table 1. Patients in the previous-day regimen group were allowed to ingest clear liquids until 11:30 pm of the day before the procedure, whereas patients in the split-dosing group were allowed to ingest clear liquids until 7:30 am of the same day of the procedure. Procedures could take place from 9:30 am to 3:00 pm. The minimum fasting time was set at 2 hours. Just before beginning the colonoscopy, the same dedicated nurse reinterviewed the patient, collecting the following data: the exact time that the sachets were ingested, the exact time of the last liquid intake, the exact start time of the EGD, and compliance with the prescribed instructions. It was established that patients had successfully completed the instructions when they had taken the 2 doses of the product and more than 75% of the liquids indicated. All colonoscopists were blinded to the preparation used. At the beginning of the EGD, immediately after passing through the cardia, all the accumulated liquid in the stomach was suctioned. The aspirated liquid was collected in a volume-graded receptacle, which was connected to the suctioning system, and disconnected when the fluid was completely removed. The volume was measured and recorded by using the meniscus of the upright fluid container. Once this was done, a sample of the liquid was taken to measure its pH by using a digital pH meter (portable pH meter pH25+; Crison, Barcelona, Spain). Bowel cleansing quality was assessed by the colonoscopist at the end of the procedure by using the Ottawa Bowel Preparation Scale (OBPS)33 and 34 (Table 2). OBPS was analyzed as a continuous variable after confirmation of normal distribution. Fasting time (FT) was defined as the interval between the last fluid ingestion and the beginning of the procedure. All of the procedures were performed in our hospital by 7 experienced staff colonoscopists having performed more than 5000 colonoscopies. All colonoscopies were performed with the intention of reaching the cecum. All colonoscopies were performed with patients under sedation with intravenous propofol, administered by or directly supervised by an anesthesiologist.

Table 1

Patient instructions for split-dosing and previous-day regimen groups


Day −2 Day −1 Day −1
Day −1
Day −1
Day −1
Day 0
Day 0
Day 0
Group 1: split-dosing regimen Low-fiber diet Light breakfast and lunch First SPMC sachet Second SPMC sachet Finish liquid ingestion Procedures
Group 2: previous-day regimen Low-fiber diet Light breakfast and lunch First SPMC sachet Second SPMC sachet Finish liquid ingestion Procedures

SPMC, Sodium picosulfate–magnesium citrate.

Table 2

Ottawa Bowel Preparation Scale


Cleanliness Fluid quantity
Right colon Mid-colon Rectosigmoid
0, no liquid; 1, minimal liquid; no suction; 2, suction required; 3, wash and suction; 4, solid stools; not washable 0, no liquid; 1, minimal liquid; no suction; 2, suction required; 3, wash and suction; 4, solid stools; not washable 0, no liquid; 1, minimal liquid; no suction; 2, suction required; 3, wash and suction; 4, solid stools; not washable 0, minimal; 1, moderate; 2, large

Total score = cleanliness of the right colon + cleanliness of the mid-colon + cleanliness of the rectosigmoid colon + fluid quantity.

Scores range from 0 (excellent preparation) to 14 (solid stools in each colon segment and with large amounts of fluid).

Based on previous studies, a sample size of 120 individuals in each arm was estimated to be necessary to detect a 10-mL difference in mean RGFV, with an SD of 20.0, with a 2-sided α value of .05 and a statistical power of 80%. The means of continuous variables that satisfied normality criteria were compared by using the Student unpaired-samples t test. Variables that did not meet normality criteria were compared by using the nonparametric Mann-Whitney U test. The χ2 test was used for comparison of categorical variables. Analysis of variance was used to compare variables between different FT interval groups. Statistical significance was established at P < .05. Factors statistically significant on univariate analysis were included in multivariate analysis. Backward stepwise multivariate linear regression analysis was used to assess factors affecting RGFV. The model was adjusted for those variables theoretically affecting gastric emptying that reached nearly significant differences (P < .02) between the split-dosing and the previous-day groups. Continuous variables were reported as mean ± SD, whereas categorical variables were presented as percentages. Data analysis was performed per protocol. To collect and process data, we used SPSS version 15.0 (IBM, Armonk, NY).


A total of 328 patients were enrolled in the study between October 2012 and May 2014. Of these, 23 patients were excluded: 1 patient in the previous-day regimen group due to withdrawal of consent, 7 patients in the previous-day regimen group and 5 in the split-dosing group due to personal delays in the procedure date, and the remaining 10 because of concomitant disorders found during the medical examination between the inclusion visit and the procedure date, which placed them in American Society of Anesthesiologists class IV (6 in the previous-day regimen group and 4 in the split-dosing group). Finally, 305 patients were included: 148 in the previous-day regimen group and 157 in the split-dosing group.

No differences in compliance with instructions were detected between groups (99.3% in split-dosing vs 98.7% in previous-day); 100% of patients had a complete colonoscopy. No adverse events related to the preparation or the procedure or pulmonary aspirations were recorded during the study.

Demographics and baseline characteristics were similar in the 2 groups (Table 3).

Table 3

Demographic and baseline characteristics


Characteristics Split-dosing group Previous-day regimen group P value
No. 157 148
Age, y 52.65 ± 13.34 55.66 ± 11.70 .08 (NS)
Male patients 78 (52.70) 70 (47.29) .67 (NS)
BMI 25.43 ± 4.10 25.33 ± 4.14 .82 (NS)
Obese patients 19 (12.10) 20 (13.51) .71 (NS)
Diabetes mellitus 3 (1.91) 5 (3.37) .41 (NS)
Bowel movements
 Constipation 11 (7.08) 11 (7.43) .88 (NS)
 Diarrhea 21 (13.37) 14 (9.45) .28 (NS)
PPI use 55 (35.03) 61 (41.21) .26 (NS)
Prokinetics 4 (2.54) 10 (6.75) .07 (NS)
Benzodiazepines 22 (14.01) 27 (18.24) .31 (NS)
Opiates 1 (0.63) 5 (3.37) .08 (NS)
Tricyclic antidepressants 18 (11.46) 14 (9.45) .56 (NS)
Fasting time, h
 Mean ± SD 3.36 ± 0.97 11.05 ± 1.86
 Median 3 11 < .001
 Range 2-6 6-18

Values are mean ± SD or number (%).

Obese patients: BMI >30 kg/m2.

NS, Not significant; BMI, body mass index; PPI, proton pump inhibitor.

The mean OBPS scores are shown in Table 4. The mean overall OBPS score and the right and mid-colon components of the OBPS were significantly better in the split-dosing group than in the previous-day regimen group. The mean rectosigmoid OBPS score was also better in the split-dosing group, but these differences were not statistically significant. The total amount of colon fluid was significantly greater in the previous-day regimen group than in the split-dosing group. No statistically significant differences in the distribution of factors related to deficient colon preparations35, 36, 37, and 38 such as male sex, chronic constipation, use of constipating medications (opioids or tricyclic antidepressants), obesity, or diabetes mellitus were detected in the 2 groups.

Table 4

Colon cleanliness quality


Split-dosing group Previous-day regimen group P value
OBPS global 3.36 ± 2.24 4.47 ± 2.34 < .001
OBPS right colon 1.17 ± 0.77 1.72 ± 0.80 < .001
OBPS mid-colon 0.86 ± 0.76 1.18 ± 0.84 < .01
OBPS rectosigmoid 0.87 ± 0.84 0.94 ± 0.85 .48 (NS)
OBPS fluid 0.48 ± 0.59 0.64 ± 0.58 < .05

Data are mean ± SD.

OBPS, Ottawa Bowel Preparation Scale; NS, not significant.

Obviously, the FT was shorter for the split-dosing group than for the previous-day regimen group (3.36 hours vs 11.24 hours, P < .001).

Figure 1 shows the association between the mean overall OBPS score and the FT when specifically studying the split-dosing group. In this group, colonoscopies performed within 3 to 4 hours of the FT consistently had the best overall and per-segment cleansing quality, as well as the smallest amount of colon liquid. With the exception of the 2- to 3-hour FT interval, a trend toward worse preparation quality as the hour intervals increased was also observed in all the components of the OBPS.


Figure 1

Fasting time influence on colon cleansing quality. Fasting time expressed as hour intervals from last liquid ingestion to the beginning of the procedure. Colon cleansing quality expressed as overall mean OBPS score. Data are mean (SD). *Interconnected columns = P < .05. OBPS, Ottawa Bowel Preparation Scale.


With respect to RGFV and RGFpH, the main results are shown in Figure 2. The RGFV was significantly lower in the split-dosing group than in the previous-day regimen group (11.09 ± 7.86 vs 18.62 ± 12.73, P < .001). Univariate analysis showed the lower RGFV to be significantly associated not only with the split-dosing regimen, but also the use of PPIs and nonobesity. However, RGFV was not affected by sex, age, the presence of diabetes mellitus, or the use of prokinetics, opioids, benzodiazepines, or antidepressants. Multivariate analysis was performed to identify factors independently involved in RGFV levels. In addition to those variables with significant differences on univariate analysis, we also included in the model those variables that are known to affect gastric emptying and were distributed with nearly significant differences (P < .02) between the split-dosing and the previous-day groups (age, prokinetics, opiates, benzodiazepines). Again, only the split-dosing regimen, the use of PPIs, and obesity were found to be independently correlated (Table 5). No significant differences in RGFpH between the split-dosing and previous-day preparations were detected (1.96 ± 1.58 vs 1.80 ± 1.20, P = .77). Only the use of PPIs was significantly associated with a higher RGFpH. No significant differences in RGFV or RGFpH between the different FTs were detected when data from the split-dosing group were analyzed separately (Fig. 3).


Figure 2

A, Residual gastric fluid volume in sodium picosulfate–magnesium citrate (SPMC) split-dosing group was significantly lower than in the previous-day SPMC group. B, No differences in residual gastric fluid pH were observed in the 2 groups.


Table 5

Multivariate linear regression analysis of residual gastric liquid volume


B 95% CI P value
Split-dosing regimen −7.99 −10.38 to 5.61 .000
Obesity 4.10 0.53 to 7.66 .024
PPI use −2.72 −5.35 to 0.10 .042
Age −0.75 −0.17 to 0.02 .144
Prokinetics −4.24 −10.00 to 1.51 .148
Opiates 0.68 −7.77 to 9.13 .874
Benzodiazepines 0.98 −2.31 to 4.28 .556

CI, Confidence interval; PPI, proton pump inhibitor.


Figure 3

Fasting time influence on residual gastric fluid volume (RGFV). No differences were found between any of the groups. Fasting time expressed as hour intervals from last liquid ingestion to the beginning of the procedure. Data are mean (SD).



SPMC-based cleansing agents have demonstrated to be effective, well-tolerated, and safe bowel preparations for colonoscopy.11, 12, 13, 14, and 15 Furthermore, there is extensive evidence that split-dosing bowel preparations are more effective than previous-day regimens when PEG,2 and 17 NaP,17 and 18 oral sulfate solutions,39 and SPMC solutions20 and 21 are used.

In our study, cleansing quality was significantly better in the split-dosing group than in the previous-day regimen group (overall mean OBPS score, 3.36 vs 4.47; P < .001). This is in line with 2 previous studies comparing this issue with the same agent as the primary outcome.20 and 21 This 1.11 difference between the 2 groups should be highlighted because, as suggested in a previous study,20 differences when using this scale are not usually greater than 1. The mean OBPS score in the split-dosing group was slightly but consistently better than that obtained in similar studies evaluating split-dosing regimens with different cleansing agents.12, 34, and 40 When analyzing the different segments, statistically significant differences were obtained in the right colon and mid-colon and for total colon fluid. The highest and most statistically significant differences between the 2 regimens were obtained in the right colon. This should be highlighted as it is in the right colon where preparations are usually less efficient, and more interval cancers and flat polyps are found,41 but, as previously demonstrated, where splitting the preparation achieves a higher yield.7, 12, 20, and 21

Various studies have previously described higher overall and right colon cleansing efficacy with shorter preparation-to-colonoscopy intervals,7, 34, 40, and 42 and therefore, European Society of Gastroenterology guidelines consider that the delay between the last dose of preparation and the colonoscopy should not be longer than 4 hours.23 We attempted to confirm whether this inverse association between FT and cleansing efficacy persisted when the split-dosing group was specifically studied. Excluding the 2- to 3-hour FT interval, we observed a trend toward a worse colon quality preparation as the hour intervals increased, suggesting that a 3- to 4-hour FT interval should be the most efficient interval. Recent studies from Seo et al34 and Manes et al21 obtained similar results with PEG and SPMC preparations, respectively.

Despite the body of evidence supporting the use of split-dosing, some resistance to the implementation of this regimen is still found in an attempt to ensure an adequate precolonoscopy sedation fasting period, which theoretically would guarantee lower residual liquid volumes in the stomach and consequently lower risk of pulmonary aspiration. This reluctance to follow anesthesia guidelines may not be necessarily due to ignorance, but to differences in interpretation. On one hand, the most recently updated guidelines from the American Society of Anesthesiologists28 advocate a clear liquid fasting period of 2 to 3 hours before elective procedures requiring anesthesia or sedation/analgesia. Although the guidelines do not explicitly mention colon cleansing preparations, they emphasize that clear liquids are not limited to the usual examples and that the volume of liquid ingested is less important than its quality. On the other hand, the studies on which these guidelines are based refer to limited volumes of water, coffee, tea, isotonic or carbohydrate drinks, and clear juices,26 rarely exceeding 500 mL, whereas colon preparations usually involve the ingestion in a short period of time of 1.5 or 2 L of liquids with osmotic particularities and controversial effects on gastric emptying.30 and 31 Faced with the doubt, it is understandable that clinicians opt for the most theoretically safe option, thus relegating split-dosing as a method to be used only as an exception.

To our knowledge, there is only 1 previous published study addressing the issue of RGFV in split-dosing bowel preparations. Huffman et al32 demonstrated that RGFV of patients undergoing same-day EGD and colonoscopy after a split-dosing regimen of NaP or PEG was not significantly different from that obtained after a previous-day regimen with the same agents.

Our study is the first to analyze RGFV and RGFpH in the use of SPMC bowel preparations. When comparing the RGFV obtained after an SPMC split-dosing regimen or an SPMC previous-day regimen, we concluded that patients in the first group had statistically significantly less liquid in the stomach, with no significant differences in pH. The observation that permitting a patient to drink clear fluids 90 to 180 minutes preoperatively may result in even lower gastric fluid volumes has been previously described,24, 26, and 27 but, to our knowledge, not with bowel preparations. We have no fully comprehensive explanation for this finding, but it could be speculated that in the split-dosing regimen, the procedure is performed at a point when gastric peristalsis secondary to the stimulant effect of the liquid is still present, independent of whether gastric emptying is slightly delayed by the higher osmotic pressure of the SPMC on the duodenum. The mean RGFV levels obtained in our study are in line with those of previous studies on FT and clear liquids.25, 26, 27, and 32 Furthermore, the RGFV difference between split-dosing and previous-day regimen groups (7 mL) is almost similar to that obtained in studies comparing standard versus shortened fasts from water before elective surgeries.26 Thus, we may conclude that SPMC in a split-dosing regimen behaves as standard clear liquid.

Multivariate analysis showed that in addition to shorter FT intervals, lower RGFV was independently associated with the use of PPIs and nonobesity. Different studies have previously described that preoperative use of PPIs decreases gastric fluid volume.43, 44, 45, and 46 With regard to obesity, previous studies have demonstrated a delay in the emptying of solids, but not of clear liquids.47 In fact, the latest European guidelines on preoperative fasting from the European Society of Anesthesiology29 explicitly state that general recommendations for clear liquids also apply to patients with obesity. Thus, our results are not in line with previous observations, suggesting that in obese patients, unlike nonobese patients, a low-volume bowel preparation such as SPMC administered in split-dosing does not behave as a clear liquid. A more extensive study focusing on this finding should be performed to clarify this point.

When the split-dosing group was studied separately, we found no statistically significant differences in RGFV or RGFpH between the different FT intervals. Both variables remained stable, and no trend was apparent. The same conclusion was obtained by Huffman et al32 in their study based on PEG and NaP. The absence of an evident “sweet spot interval” of lowest gastric content may allow us to consider that fasting intervals should be managed exclusively in terms of colon cleansing efficacy when the split-dosing regimen of SPMC is used, and thus, a 3- to 4-hour FT interval may be prescribed if not contraindicated by other issues.

Several limitations to this study should be mentioned. First, it was not a randomized multicenter study but rather an observational single-center study, which may allow the interference of confounding factors and limit the generalizability of the results. However, we believe that, although not strictly randomized, the assigning of patients to each group exclusively depending on the hour of the medical visit ensures a random distribution, limiting the presence of confounding factors. Second, the results cannot be extrapolated to inpatients as the study exclusively included outpatients. The same is obviously true for those patients with conditions listed in the exclusion criteria. Finally, we should highlight the role of the exclusively dedicated nurse. Patient education has been shown to be an important factor for the successful outcome of colonoscopy,4, 48, and 49 and we believe that this is the key factor behind the high percentage of compliance and adequate preparations.

In summary, when SPMC is used, colon-cleansing quality is significantly better with a split-dosing regimen than with a previous-day regimen. This improvement is greater in the right colon. Once a split-dosing SPMC regimen is prescribed, a 3- to 4-hour FT interval seems to be the most effective, with the highest colon cleansing quality and lowest quantity of colon fluid. Compared with a previous-day regimen, the RGFV is significantly decreased when SPMC in a split-dosing regimen is prescribed. No differences in RGFpH are detected. Split-dosing, PPI use, and nonobesity are independent factors contributing to a lower GRFV. As such findings are consistent with results reported in previous studies comparing traditional and shortened fasting periods for clear liquids (with the exception of nonobesity), we can conclude that SPMC administered in a split-dosing regimen behaves as a standard clear liquid, and thus anesthesia guidelines on this issue may be applied with no significant concerns.


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1 Gastroenterology Department, Clínica Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, Pamplona, Spain

2 Anesthesiology Department, Clínica Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, Pamplona, Spain

Reprint requests: César Prieto de Frías, MD, PhD, Servicio de Digestivo, Clínica Universidad de Navarra, 31008 Pamplona, Spain.

DISCLOSURE: All authors disclosed no financial relationships relevant to this publication.

© 2016 by the American Society for Gastrointestinal Endoscopy

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