The addition of capnography monitoring to standard of care during procedural sedation for endoscopic procedures provides a patient safety benefit, a study has found. According to the study, capnography reduced the proportion of patients experiencing greater than one adverse event (AE) by more than 27%.
“Reductions in adverse events result in a reduced cost of procedure that more than accounts for the purchase price of the monitor and disposables,” said Rhodri Saunders, DPhil, health economist at Ossian Health Economics and Communications in Basel, Switzerland. “Cost concerns regarding capnography are likely to be unfounded, and it may be time to reopen guideline discussions.”
As Dr. Saunders reported at the 2015 annual meeting of the American Society of Anesthesiologists (abstract A4163), sedation and analgesia are commonly used to improve patient acceptance and comfort during outpatient procedures, but these methods come with risks. Adverse events, for example, such as severe desaturation, occur in 6% to 20% of GI endoscopy procedures (Scand J Gastroenterol 2013;48:1222-1223).
“Standard of care monitoring is pulse oximetry and visual assessment,” said Dr. Saunders, “but capnography monitors exhaled carbon dioxide and allows for real-time evaluation of patient ventilation.”
Despite these comprehensive measurements, however, the procedure remains underutilized, Dr. Saunders noted, because of concerns about costs and clinical utility.
Economics of Capnography
In order to test the economic viability of capnography, researchers developed a decision tree model of sedation, including AEs, interventions, outcomes and costs. The model compared outcomes using standard of care versus standard of care plus capnography during GI endoscopy. Patients were theoretically exposed to the risk of each AE, the rates of which were determined from randomized controlled trials and large studies.
The cost of interventions and staffing was derived from an analysis of the Premier database. Capnography monitoring, Dr. Saunders reported, costs $4,000 per monitor and an average of $16 per procedure for disposables.
In addition, training was assumed to take four times as long for capnography than for standard of care.
“In short,” said Dr. Saunders, “we performed a literature search for randomized controlled trials and prospective studies to inform this health economic model of procedural sedation. We also did a second search to look for costs associated with all of the adverse events that can happen.”
Reduced Adverse Events
According to the model, 34.18% of patients experienced an AE with standard of care compared with only 24.89% with capnography monitoring. The number needed to treat to avoid one AE was seven, and the most commonly avoided AE was apnea.
“Reduced adverse events led to reduced incidence of adverse outcomes,” said Dr. Saunders, “and increased patient safety led to a mean cost savings with capnography of $85 per procedure ($156 vs. $241 with standard of care).”
A sensitivity analysis comprising 5,000 simulations confirmed the findings of the initial model: Researchers found that the mean cost savings was actually $75, fluctuating from only $10 lost to over $300 saved.
“If you’re unlucky at your hospital,” said Dr. Saunders, “2% to 3% of the time you might see that capnography is going to increase the cost of doing procedures, but it’s a rare and negligible sum.
“Overall, capnography doesn’t seem to be more expensive,” he concluded. “You’re most likely saving money.”
Supplemental Oxygen Confounds
Moderator of the session, Julian M. Goldman, MD, an anesthesiologist specializing in clinical care and pain medicine at Massachusetts General Hospital, in Boston, said the research demonstrates the community need to solve a very challenging problem.
“The meta-message,” said Dr. Goldman, “is that we still have studies being formed, investigations being performed and questions being asked about what is the best way to monitor patients for respiratory depression in a way that would provide early warning of significant respiratory depression. That’s what the community is looking for, and you’re seeing that expressed in this presentation.”
The problem is complicated, Dr. Goldman explained, by supplemental oxygen, which raises the arterial oxygen levels so that a patient may have to stop breathing for longer periods of time before desaturation.
“As the researchers pointed out, supplemental oxygen confounds a number of ways of measuring. Patients may stop breathing briefly, but they don’t desaturate because they start breathing on their own, maybe because their carbon dioxide is building up.
“If this were a solved problem, you wouldn’t continue to see posters and research,” Dr. Goldman concluded, “but it’s still a challenging issue.”
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