Pam Harrison

October 21, 2014

PHILADELPHIA — Capnographic monitoring to detect early changes in breathing during routine colonoscopy does not capture more episodes of hypoxemia in moderately sedated healthy adults, the first randomized controlled trial evaluating the technology suggests.

"We know moderate sedation for colonoscopy is extremely safe; it's been used on millions of patients," said Paresh Mehta, MD, a former fellow at the Cleveland Clinic, and currently with the Gastroenterology Consultants of San Antonio.

"Does adding a device that costs more money, that requires extra training, that we are not sure even works in patients who may not need it worth it?," he asked.

"I believe this study provides initial evidence that some patient populations, especially healthy adults who are American Society of Anesthesiologists [ASA] physical classification I or II, can safely undergo these procedures without capnographic monitoring, at least when looking at hypoxemia as an outcome," he told Medscape Medical News.

The finding, presented here at the American College of Gastroenterology 2014 Annual Scientific Meeting, counters the recently updated ASA practice guidelines that require capnography when moderate sedation is used during colonoscopy or other procedures.

Dr Mehta and colleagues studied 234 adults scheduled for routine outpatient colonoscopy. Patients were given midazolam for sedation and either fentanyl or meperidine for pain control.

Does adding a device that costs more money, that requires extra training, that we are not sure even works in patients who may not need it, worth it?

The adults were randomized to either an open or blinded capnography alarm group. Both groups were well matched, and there were no significant differences in body mass index or in patient history of heart or pulmonary disease. In addition to capnographic monitoring, standard cardiopulmonary monitoring devices were used in both groups.

The primary end point of the study was the incidence of hypoxemia, defined as a drop in oxygen saturation to below 90% for at least 10 seconds over a 1-minute period.

Secondary end points included the incidence of severe hypoxia, defined as a drop in oxygen saturation to below 85% at any time during the procedure, the incidence of apnea, disordered respiration, hypotension, bradycardia, and early procedure termination for any cause.

The incidence of severe hypoxia occurred more frequently in the blinded alarm group than in the open alarm group (18.3% vs 6.0%; = .004). There were no differences in the primary or the other secondary end points between the two groups.

Table. Outcomes in the Two Groups

Outcome Open Alarm Group (%) Blinded Alarm Group (%)
Hypoxemia 53.8 54.8
Apnea 56.4 64.4
Hypoventilation 56.4 63.5
Hypotension 11.1 14.8
Bradycardia 18.8 14.8
Pseudo apnea 22.2 16.5


Capnographic monitoring is still important for the detection of early changes in breathing patterns when deeper sedation, such as propofol, is being used, or when patients need to be placed under general anesthesia, the researchers note.

"The difference here," Dr Mehta explained, is that you’ve mandated something without any evidence of benefit with moderate sedation. Yet capnography increases the cost of colonoscopy because all endoscopy centers have to purchase these devices and specialized nasal cannulas. In addition, "you have to train your staff how to use the device because not everybody is familiar with looking at waves forms and making decisions off that," he pointed out.

Before labelling a lot of newer technologies as standard of care, "I think we need to see clear signs of benefit," said Ashwin Ananthakrishnan, MD, from Massachusetts General Hospital in Boston.

This added technology "did not seem to make a difference in detecting hypoxemia," he told Medscape Medical News. "In at least this population of patients, we need to know the minimum acceptable level of monitoring, and then we need to tailor monitoring guidelines to patients more likely to have complications, rather than insisting that every unit have this technology and that it be used for every procedure."

Dr Mehta and Dr Ananthakrishnan report no relevant financial relationships.

American College of Gastroenterology (ACG) 2014 Annual Scientific Meeting: Abstract 6. Presented October 20, 2014.


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