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Bowel Prep for Ambulatory Endoscopy
P E R I O P E R AT I V E GRAND ROUNDS Bowel Prep for Ambulatory Endoscopy The Case A 73-year-old woman asked her primary care physician for a referral for colonoscopy. Her physician referred her to a gastroenterologist whose practice consists of ambulatory endoscopy. In his practice, patients are not routinely seen in advance of their procedures, so the patient called the gastroenterologist’s office to be given instructions for her bowel prep. Because the patient is 4 ft 10 inches tall and weighs only 88 lbs, she inquired whether the “dose” of the prep needed adjustment given her small size. The nurse told her that this was the stan-
dard dose, and the nurse did not ask the patient any additional questions. The patient used the bowel prep as instructed. Her husband found her unresponsive on the morning of her scheduled colonoscopy, and she was taken to the hospital. She was found to have significant electrolyte abnormalities including hyponatremia, hypokalemia, hypophosphatemia, hypocalcemia, and hypomagnesemia, all believed to be complications of the bowel prep. She was rehydrated, her electrolytes were corrected, and she was discharged home after 48 hours.
Discussion In order for a gastroenterologist to perform a safe and accurate colonoscopy, the contents of the patient’s colon need to be evacuated. Polyethylene glycol electrolyte lavage solution (PEG-ELS) and oral sodium phosphate (NaP) are two major classes of colonoscopy preparations; each works by a different mechanism. The PEG-ELS preparations are osmotically balanced, nonabsorbable electrolyte solutions that cleanse the bowel by simple washout of ingested fluid without causing significant fluid and electrolyte shifts. Using this preparation requires that one gallon of the liquid be ingested during a two-hour period, which some patients may have difficulty completing, both because of the volume and the taste. If the patient is
unable to complete the preparation, the bowel will be inadequately prepped, but complications are rare. The major alternatives are hyperosmotic preparations containing NaP, which draw plasma water into the bowel lumen to achieve the fluid washout. The patient must drink other liquids to replace this fluid shift. Oral NaP preparations should not be used in patients with renal disease, congestive heart failure, or ascites.1 A meta-analysis of eight randomized trials comprising 1,286 participants suggested that PEG-ELS and NaP are largely equivalent, including for adverse reactions, although NaP may be better tolerated by patients.2 The specific bowel cleansing regimen given to the patient in this case is (continued on page 608)
This content is adapted from Morbidity & Mortality Rounds on the Web, Cases and Commentaries with permission from the Agency for Healthcare Research and Quality (http://www.webmm.ahrq.gov/case.aspx?caseID=67. Accessed August 24, 2009). The original commentary was written by Douglas B. Nelson, MD, and was adapted for this article by Nancy J. Girard, PhD, RN, FAAN.
628 • AORN JOURNAL • OCTOBER 2009, VOL 90, NO 4
© AORN, Inc, 2009
Perioperative Grand Rounds
OCTOBER 2009, VOL 90, NO 4
(continued from page 628)
Perioperative Grand Rounds
not stated, but the subsequent electrolyte disturbances reported have been associated with oral NaP-based preparations.3-6 Although the package insert for this over-the-counter medication does give a dosage range, it is not weight-based. The only reference to a lower dosage adjustment is for older adult patients, although clinically, it is rarely used. In fact, no dosage adjustment was made for age in any of the randomized trials mentioned above, and patient age ranged to as high as 90 years. In practice, the standard dose—45 mL given on two occasions before the procedure—is used routinely in nearly all patients. Unless this patient was unable to adequately drink fluids, it would be hard to state that an error was made here, except in retrospect. The failure of the nurse to inquire about other medical conditions that might contraindicate this bowel preparation is a potential source of error, although it is not stated that the patient had any of these conditions. Approximately 4 million to 5 million colonoscopy procedures are performed annually in the United States.7 Although the procedure is
relatively safe, there are risks that should be discussed with patients as part of the informed consent process. It is difficult to estimate the rate of complications from the bowel prep itself, and the fact that these are largely limited to case reports over the last 30 years, despite the tremendous volume of procedures performed annually, suggests that this is an extremely rare complication. The patient’s primary care provider should assess whether the patient’s overall medical condition would allow him or her to benefit from colorectal cancer screening. Before the colonoscopy, the endoscopist reviews the patient’s medical record to assess the patient’s risk. Adverse effects from PEG-ELS are virtually unheard of. If a NaP bowel prep is used, it may be beneficial to schedule a preprocedural visit to determine whether the patient has one of the medical conditions, such as renal insufficiency or heart failure, that would preclude the use of this agent. Preventing adverse events may be best accomplished by appreciating the relative contraindications of NaP preparations.
Perioperative Points
•
• •
The nurse should be aware of basic information regarding a new patient referred for a colonoscopy and be sure the patient understands preprocedural instructions. The nurse should notify the endoscopist and primary care provider of potential patientrelated risk factors. The nurse must be knowledgeable about the
•
prep solutions and their effects in order to more effectively inform patients. Although PEG-ELS is remarkably safe, it is sometimes poorly tolerated. Sodium phosphate is easier to tolerate, but can cause electrolyte shifts. If prescreening is deemed necessary, the patient’s referring care provider should share vital information with the gastroenterologist.
References 1. Nelson DB, Barkun AN, Block KP, et al. Technology Status Evaluation report. Colonoscopy preparations. May 2001. Gastrointest Endosc. 2001;54(6):829-832. 2. Hsu CW, Imperiale TF. Meta-analysis and cost comparison of polyethylene glycol lavage versus sodium phosphate for colonoscopy preparation. Gastrointest Endosc. 1998;48(3):276-282. 3. Fass R, Do S, Hixson LJ. Fatal hyperphosphatemia following Fleet Phospho-Soda in a patient with colonic ileus. Am J Gastroenterol. 1993;88(6):929-932. 4. Vukasin P, Weston LA, Beart RW. Oral Fleet Phospho-Soda laxative-induced hyperphosphatemia and hypocalcemic tetany in an adult: report of a case.
608 • AORN JOURNAL
Dis Colon Rectum. 1997;40(4):497-499. 5. Boivin M, Kahn SR. Symptomatic hypocalcemia from oral sodium phosphate: a report of two cases. Am J Gastroenterol. 1998;93(12):2577-2579. 6. Beloosesky Y, Grinblat J, Weiss A, Grosman B, Gafter U, Chagnac A. Electrolyte disorders following oral sodium phosphate administration for bowel cleansing in elderly patients. Arch Intern Med. 2003; 163(7):803-808. 7. Winawer SJ, Zauber AG, Ho MN, et al. Prevention of colorectal cancer by colonoscopic polypectomy. The national polyp study workgroup. N Engl J Med. 1993;329(27):1977-1981.
dard dose, and the nurse did not ask the patient any additional questions. The patient used the bowel prep as instructed. Her husband found her unresponsive on the morning of her scheduled colonoscopy, and she was taken to the hospital. She was found to have significant electrolyte abnormalities including hyponatremia, hypokalemia, hypophosphatemia, hypocalcemia, and hypomagnesemia, all believed to be complications of the bowel prep. She was rehydrated, her electrolytes were corrected, and she was discharged home after 48 hours.
Discussion In order for a gastroenterologist to perform a safe and accurate colonoscopy, the contents of the patient’s colon need to be evacuated. Polyethylene glycol electrolyte lavage solution (PEG-ELS) and oral sodium phosphate (NaP) are two major classes of colonoscopy preparations; each works by a different mechanism. The PEG-ELS preparations are osmotically balanced, nonabsorbable electrolyte solutions that cleanse the bowel by simple washout of ingested fluid without causing significant fluid and electrolyte shifts. Using this preparation requires that one gallon of the liquid be ingested during a two-hour period, which some patients may have difficulty completing, both because of the volume and the taste. If the patient is
unable to complete the preparation, the bowel will be inadequately prepped, but complications are rare. The major alternatives are hyperosmotic preparations containing NaP, which draw plasma water into the bowel lumen to achieve the fluid washout. The patient must drink other liquids to replace this fluid shift. Oral NaP preparations should not be used in patients with renal disease, congestive heart failure, or ascites.1 A meta-analysis of eight randomized trials comprising 1,286 participants suggested that PEG-ELS and NaP are largely equivalent, including for adverse reactions, although NaP may be better tolerated by patients.2 The specific bowel cleansing regimen given to the patient in this case is (continued on page 608)
This content is adapted from Morbidity & Mortality Rounds on the Web, Cases and Commentaries with permission from the Agency for Healthcare Research and Quality (http://www.webmm.ahrq.gov/case.aspx?caseID=67. Accessed August 24, 2009). The original commentary was written by Douglas B. Nelson, MD, and was adapted for this article by Nancy J. Girard, PhD, RN, FAAN.
628 • AORN JOURNAL • OCTOBER 2009, VOL 90, NO 4
© AORN, Inc, 2009
Perioperative Grand Rounds
OCTOBER 2009, VOL 90, NO 4
(continued from page 628)
Perioperative Grand Rounds
not stated, but the subsequent electrolyte disturbances reported have been associated with oral NaP-based preparations.3-6 Although the package insert for this over-the-counter medication does give a dosage range, it is not weight-based. The only reference to a lower dosage adjustment is for older adult patients, although clinically, it is rarely used. In fact, no dosage adjustment was made for age in any of the randomized trials mentioned above, and patient age ranged to as high as 90 years. In practice, the standard dose—45 mL given on two occasions before the procedure—is used routinely in nearly all patients. Unless this patient was unable to adequately drink fluids, it would be hard to state that an error was made here, except in retrospect. The failure of the nurse to inquire about other medical conditions that might contraindicate this bowel preparation is a potential source of error, although it is not stated that the patient had any of these conditions. Approximately 4 million to 5 million colonoscopy procedures are performed annually in the United States.7 Although the procedure is
relatively safe, there are risks that should be discussed with patients as part of the informed consent process. It is difficult to estimate the rate of complications from the bowel prep itself, and the fact that these are largely limited to case reports over the last 30 years, despite the tremendous volume of procedures performed annually, suggests that this is an extremely rare complication. The patient’s primary care provider should assess whether the patient’s overall medical condition would allow him or her to benefit from colorectal cancer screening. Before the colonoscopy, the endoscopist reviews the patient’s medical record to assess the patient’s risk. Adverse effects from PEG-ELS are virtually unheard of. If a NaP bowel prep is used, it may be beneficial to schedule a preprocedural visit to determine whether the patient has one of the medical conditions, such as renal insufficiency or heart failure, that would preclude the use of this agent. Preventing adverse events may be best accomplished by appreciating the relative contraindications of NaP preparations.
Perioperative Points
•
• •
The nurse should be aware of basic information regarding a new patient referred for a colonoscopy and be sure the patient understands preprocedural instructions. The nurse should notify the endoscopist and primary care provider of potential patientrelated risk factors. The nurse must be knowledgeable about the
•
prep solutions and their effects in order to more effectively inform patients. Although PEG-ELS is remarkably safe, it is sometimes poorly tolerated. Sodium phosphate is easier to tolerate, but can cause electrolyte shifts. If prescreening is deemed necessary, the patient’s referring care provider should share vital information with the gastroenterologist.
References 1. Nelson DB, Barkun AN, Block KP, et al. Technology Status Evaluation report. Colonoscopy preparations. May 2001. Gastrointest Endosc. 2001;54(6):829-832. 2. Hsu CW, Imperiale TF. Meta-analysis and cost comparison of polyethylene glycol lavage versus sodium phosphate for colonoscopy preparation. Gastrointest Endosc. 1998;48(3):276-282. 3. Fass R, Do S, Hixson LJ. Fatal hyperphosphatemia following Fleet Phospho-Soda in a patient with colonic ileus. Am J Gastroenterol. 1993;88(6):929-932. 4. Vukasin P, Weston LA, Beart RW. Oral Fleet Phospho-Soda laxative-induced hyperphosphatemia and hypocalcemic tetany in an adult: report of a case.
608 • AORN JOURNAL
Dis Colon Rectum. 1997;40(4):497-499. 5. Boivin M, Kahn SR. Symptomatic hypocalcemia from oral sodium phosphate: a report of two cases. Am J Gastroenterol. 1998;93(12):2577-2579. 6. Beloosesky Y, Grinblat J, Weiss A, Grosman B, Gafter U, Chagnac A. Electrolyte disorders following oral sodium phosphate administration for bowel cleansing in elderly patients. Arch Intern Med. 2003; 163(7):803-808. 7. Winawer SJ, Zauber AG, Ho MN, et al. Prevention of colorectal cancer by colonoscopic polypectomy. The national polyp study workgroup. N Engl J Med. 1993;329(27):1977-1981.