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Capnographic monitoring unhelpful for routine endoscopy
Last Updated: 2016-03-04
By Marilynn Larkin
NEW YORK (Reuters Health) - Capnographic monitoring offers no additional safety benefit in healthy patients who receive moderate sedation during routine endoscopic procedures such as esophagogastroduodenoscopy (EGD) and colonoscopy, researchers report.
In 2010, the American Society of Anesthesiologists (ASA) updated its standards by requiring the use of capnographic monitoring for all procedures done under moderate sedation. Capnography monitoring measures the CO2 concentration throughout the respiratory cycle, which allows for real-time evaluation of various respiratory events, including respiratory depression and apnea.
The new requirements "presented an important change to the standard of monitoring care for many medical specialists who use moderate sedation for inpatient and ambulatory procedures, as the ASA standards dictate hospital, ambulatory surgical, and endoscopy center sedation privilege credentialing in the United States. The (capnography) devices also come with increased cost due to specialized equipment and training personnel to learn how to interpret alarms and pseudo-alarms that can occur during the procedures," the authors explain in an article online February 23 in the American Journal of Gastroenterology.
To investigate the potential benefit of the new standard, Dr. John Vargo of Cleveland Clinic in Ohio and colleagues randomly assigned 452 healthy patients (ASA Physical Classification l and ll) undergoing routine outpatient EGD (218 patients) or colonoscopy (234 patients) under moderate sedation to a blinded capnography alarm or open capnography alarm group. Standard cardiopulmonary monitoring devices were used in both groups, in addition to capnographic monitoring.
In the open arm, an independent observer signaled all respiratory abnormalities -- for example, hypoventilation, disordered respirations, pseudo-apnea -- on the capnography monitor. In the blinded arm, no signals were given for any ventilatory abnormalities, although for patient safety the endoscopy team would be alerted if a patient experienced apnea lasting 30 seconds or more. The endoscopy team was blinded to the capnography findings in both arms.
There was no significant difference in rates of hypoxemia between the blinded and open capnography arms, and the authors concluded that "capnographic monitoring in routine EGD or colonoscopy for ASAPS l and ll patients does not reduce the incidence of hypoxemia."
Dr. Vargo, chairman of the department of gastroenterology and hepatology at Cleveland Clinic, told Reuters Health by email that the study "is the first of its kind to look at the safety and benefit of using capnography monitoring in healthy patients receiving moderate sedation during ambulatory endoscopy procedures."
"The benefit of capnography monitoring in patients with anesthesiologist-directed sedation has been documented. But I couldn't find any data for moderate sedation, so we designed this study to answer this important question," he explained.
"The regulatory implications (of the findings) can be far reaching," Dr. Vargo continued. "Capnography monitoring involves financial resources, including the cost of equipment and training. This study can help regulatory entities further refine the requirements" for those who should receive such monitoring.
In an email comment, Dr. David Greenwald, director of clinical gastroenterology and endoscopy at The Mount Sinai Hospital in New York City, said the study "is important because it demonstrates no additional detection of hypoxemia through the use of capnography in relatively low-risk patients undergoing endoscopy and colonoscopy with moderate sedation, typically through the use of a narcotic and benzodiazepine combination."
"As ASA 1 and ASA 2 patients comprise the majority of those undergoing outpatient GI endoscopy, the findings provide a rationale for saying that capnographic monitoring is without benefit and burdensome in this group of patients. In an era of appropriate continued concern about the cost of delivering endoscopic care, this study provides a rationale for cost containment," said Dr. Greenwald, who was not involved in the research.
"Additional studies might lead to consideration of a revision of the anesthesiology standards for the use of capnography in gastrointestinal endoscopy," he added. "However, it is also important to note that capnography measures apnea more reliably than does pulse oximetry, and so the use of capnography may provide benefit in some high-risk populations, particularly in obese patients undergoing colonoscopy. More studies are needed to show the benefit of capnography in those higher risk patients."
Dr. Vargo has embarked on such research, noting in his email that his current work "is on identifying the safety benefit of using capnography monitoring in patients with sleep apnea and morbid obesity who are undergoing routine endoscopic procedures."
Am J Gastroenterol 2016.