Use of Capnography in EGD and Colonoscopy With Moderate Sedation.

The majority of gastrointestinal endoscopic procedures currently performed in the United
States are done under moderate sedation, primarily utilizing the combination of an opioid
and benzodiazepine. The endoscopy team administers the medications, most commonly the
endoscopy nursing team at the discretion of the endoscopist, with careful cardiopulmonary
monitoring during the procedure. The use of sedation can lead to serious unplanned adverse
events. Cardiopulmonary events related to the use of sedation in GI endoscopy include
hypotension, hypoxia, and hypopnea/apnea. The most common of these adverse events is
hypoxia, which can occur in 10-70% of patients. Although most of these events are transient
and respond to supplemental oxygenation, studies have shown electrocardiographic signs of
cardiac ischemia in patients with no known preexisting heart disease. Pulse oximetry can
help detect hypoxia related to perfusion deficits (cardiac) or ventilation factors
(respiratory) however, it is not designed to detect ventilator precursors of alveolar
hypoventilation, which primarily present as decreased respiratory rate or hypopnea/apnea.

Capnography utilizes the near-infrared spectrophotometric absorption spectrum of carbon
dioxide (CO2) at 420 nm to provide graphic assessment of the ventilation status via the
partial pressure of carbon dioxide during the respiratory cycle. Previous studies have shown
it to improve safety by detecting early indicators of hypoxia and/or signs of alveolar
hypoventilation. Studies have shown that when targeting deep sedation in advanced endoscopic
procedures utilizing capnography was superior to pulse oximetry alone in detecting
respiratory depression. There is also evidence that shows utilizing capnography in advanced
endoscopic procedures significantly decreased the incidence of hypoxia versus standard
monitoring with the procedural team blinded to the capnographic data (132 blinded vs. 49
open, P<.001) and rates of hypoxia (69% blinded vs. 46% open, P<.001) were significantly
lower with capnography monitoring.

Routine esophagogastroduodenoscopy (EGD) and colonoscopy with moderate sedation is safe with
rates of sedation associated adverse events occurring in 8 per 100,000 cases. Lightdale and
colleagues showed in a prospective, double blinded randomized controlled trial in a
pediatric population undergoing routine EGD or colonoscopy targeting moderate sedation with
opioid-benzodiazepine combinations that patients in the intervention capnography arm were
less likely (4% vs. 20%, P<.03) to have an intra-procedural episodes of hypoxia (defined as
SpO2<95% for >5sec). No adverse events related to episodes of hypoxia were reported in this
trial, but it was underpowered to evaluate this outcome. To our knowledge, there is no data
on use of capnography in adult patients undergoing EGD and colonoscopy targeting moderate
sedation with the combination of an opioid and benzodiazepine.

The American Society of Anesthesiology (ASA) has recently updated their standards for basic
anesthetic monitoring to now state that during moderate sedation all patients should have
capnographic monitoring. This was updated from the previous standards for basic monitoring
that stated capnography could be used during these levels of sedation. This is a significant
change in the practice model for monitoring patients undergoing routine endoscopy with
moderate sedation and, as the standards for basic monitoring are often used as a basis for
regulatory guidelines applied to hospital or ambulatory care centers, the addition of
requiring capnographic monitoring changes the landscape of procedural sedation for
gastrointestinal endoscopy across the United States. The evidence cited for this update in
monitoring guidelines included the Lightdale pediatric endoscopy study and our groups study
that utilized capnography in advanced endoscopic procedures. There was no data available in
adult patients undergoing routine EGD or colonoscopy at the time of the updated guidelines.
The extrapolation of advanced endoscopic procedures to routine endoscopy is of limited use
as the procedures are targeting different levels of sedation (deep vs. moderate,
respectively) and the length of the procedures is significantly different.

The rationale for not using capnography in moderate sedation arises from its ability to lead
to false alarms, such as pseudo-apnea secondary to swallowing or failure to monitor both the
oral and nasal airways for respiratory activity, as some patients will transition to nasal
or mouth breathing during sedation. These alarms during a procedure may lead to
interruption, delay, or early termination. Increased costs for capnography equipment and
having appropriately trained endoscopy team members to interpret capnography results will be
difficult to accomplish with no patient data supporting the effectiveness of its use in
routine EGD and colonoscopy.

Inclusion Criteria:

- >18yrs with full decision making capacity

- Scheduled for elective upper endoscopy or colonoscopy with moderate sedation

Exclusion Criteria:

- ASAPS class III or higher.

- History of a demonstrated allergy or intolerance to a benzodiazepine or opioid

- Patients scheduled for both upper endoscopy and colonoscopy during the same endoscopy
day