Effective bowel cleansing before colonoscopy : a randomized study of split vs. non-split dosage regimens of high vs. low-volume polyethylene glycol solutions Riccardo Marmo, MD, Gianluca Rotondano, MD, Giovanni Riccio, MD Armando Marone, MD, Maria Antonia Bianco, MD, Italo Stroppa, MD Polla, Torre del Greco, Rome, Italy GASTROINTESTINAL ENDOSCOPY 2010 : VOL 72 : 313~320 R3 박지영

BACKGROUND  Accuracy and safety of colonoscopy Depend on the quality of colon cleansing  Inadequate bowel preparation  Missed lesions, aborted procedures, complication rates↑  The ideal preparation for colonoscopy Reliably and rapidly empty the colon of all fecal material No gross or histologic alteration of the colonic mucosa Discomfort ↓, shifts in fluid or electrolyte balances ↓  Polyethylene glycol (PEG) : non-absorbable solution  Pass through the bowel without net absorption or secretion  Significant fluid and electrolyte balance shifts ↓

BACKGROUND  Large volumes (4 L) In divided doses : as effective, better tolerated than the bolus  High molecular weight PEG + ascorbic acid Cathartic effects of ascorbic acid : due to its absorption mechanism Excess ascorbic acid  not absorbed  remains in the bowel  exerts an osmotic effect  acting synergistically with PEG Reduces the volume patients have to drink  The role of split-dosage intake and the optimal duration of the interval between the completion of bowel preparation for low-volume PEG solutions  No available data

OBJECTIVES To evaluate the degree of colon cleansing in patients undergoing colonoscopy, comparing the modality of administration (split vs. non-split dosage) of two different volumes of PEG (low vs. high) To identify predictors of poor bowel cleansing

METHODS  Single-blind, active control, prospective, randomized study  Adult patients undergoing routine elective colonoscopy  Exclusion criteria Pregnant or lactating women, <18 years old Significant gastroparesis, gastric outlet obstruction, ileus Severe chronic renal failure (Ccr<30 mL/min) Severe congestive heart failure (NYHA class III or IV) Dehydration, severe acute inflammatory disease Uncontrolled hypertension (sBP ≥170 mmHg, dBP ≥100 mm Hg) Toxic colitis, megacolon

METHODS  High volume solution PEG electrolytes (sodium sulphate, sodium bicarbonate, sodium chloride, potassium chloride) Diluted into 4 L of plain water  Low volume solution Macrogol electrolytes (sodium sulphate, sodium chloride, potassium chloride) g ascorbic acid Diluted into 2 L of plain water

METHODS  Non-split-dosage schedule Entire dose in the evening of the day before the colonoscopy 1L /2hours for low volume, 2L/2hours for high volume  Split-dosage schedule Half the dose : in the afternoon before the day of the colonoscopy Half the dose : early in the morning on the day of the colonoscopy

METHODS  Bowel cleansing : assessed by colonoscopists  Segmental scoring scale of 1 ~ 4 by using an inverted Ottawa scale ScaleThe degree of Bowel cleansing 4 (excellent)empty and clean 3 (good)clear liquid, easy to aspirate 2 (fair)brown liquid or small amounts of semisolid residual stool, partially removable by suction 1 (poor)large amounts of fecal residue, not removable

METHODS  Standardized questionnaire Compliance, tolerance, additional fluid intake, acceptability Any adverse events related to bowel preparation (nausea, vomiting, bloating, abdominal pain, headache)  Primary endpoint The degree of colon cleansing

RESULTS

Figure 3. Degree of colon cleansing according to the volume of PEG and intake schedules

Figure 4. Degree of colon cleansing according to the time elapsed from the last fluid intake and colonoscopy (2-hour intervals)

RESULTS  Low-volume PEG + ascorbic acid group Significantly superior palatability Taste : good or acceptable - 54% (47% the standard PEG solution group)  Cecal intubation failed in 47 patients (5.4%) 41/354 patients (11.7%) : fair/poor bowel cleansing 6/513 patients (1.2%) : good/excellent bowel cleansing  The degree of bowel cleansing associated with the cecal intubation rate

RESULTS  Polyp detection rate in 201 of 868 patients (23.1%) fair/good (57/209, 27.3%) or good/excellent (126/512, 24.6%) > poor/fair (18/ 147, 12.2%) (P.001).  Independent predictors of poor bowel cleansing Male sex (OR 1.45 [95% CI, ], P=.014) Non-split-dosage intake schedule (OR 2.08 [ ], P=.0001)  Constipation : not an independent predictor of poor bowel cleansing (OR 1.12 [95% CI, ], P=1.65)

CONCLUSIONS  A split-dosage intake schedule provides the most effective bowel cleansing, especially in the right colon segments, irrespective of the PEG volume (low or high)  The split-dosage intake schedule likely enhances the cecal intubation and polyp detection rates  Low- volume PEG plus ascorbic acid is as effective and is tolerated as well as high-volume PEG, but it has improved palatability  Colonoscopies should be performed within a maximum of 6 to 8 hours of the last fluid intake