Use of capnography in emergency department patients being sedated for procedures

Review question

Will carbon dioxide detection monitoring help reduce heart, lung, and airway complications for emergency department patients being sedated for painful procedures?


Medications are often used in order to reduce pain or awareness (or both) for patients having painful procedures. Sometimes, complications involving a patient's heart, lungs, or airway (breathing tubes) can occur due to these medicines (e.g. vomit inhaled by the lungs). Healthcare workers monitor heart rate, blood pressure, breathing rate, and blood oxygen content to help prevent complications.

Capnography (measuring carbon dioxide gas as a patient breathes out) use has been proposed to further increase the safety of sedating patients in the emergency department. This study was performed to determine if capnography makes a difference when added to standard monitoring.

Study characteristics

We searched for studies using multiple research databases, conference research abstracts, and by contacting experts in the field. The evidence is current to August 2016. We only considered studies with participants being sedated for procedures in the emergency department. We only included studies that compared capnography and standard monitoring to standard monitoring only.

The main outcomes involved events of low blood oxygen content, low blood pressure, and vomiting. We also recorded how many times the healthcare providers had to help the patient breathe easier. This could mean simple actions such as opening of the mouth to more serious manoeuvres such as mechanically breathing for the patient.

Three studies with 1272 people, containing moderate evidence, were included in our study.

Key results

There was no difference in heart, lung, or airway complications with the addition of capnography. When only adults were studied, healthcare providers performed more manoeuvres to help the patient breathe when capnography was used. This could be due to false alarms.

Quality of evidence

The level of evidence was determined to be moderate.

Authors' conclusions: 

There is a lack of convincing evidence that the addition of capnography to standard monitoring in ED PSA reduces the rate of clinically significant adverse events. Evidence was deemed to be of moderate quality due to population and outcome definition heterogeneity and limited reporting bias. Our review was limited by the small number of clinical trials in this setting.

Read the full abstract...

Procedural sedation and analgesia (PSA) is used frequently in the emergency department (ED) to facilitate painful procedures and interventions. Capnography, a monitoring modality widely used in operating room and endoscopy suite settings, is being used more frequently in the ED setting with the goal of reducing cardiopulmonary adverse events. As opposed to settings outside the ED, there is currently no consensus on whether the addition of capnography to standard monitoring modalities reduces adverse events in the ED setting.


To assess whether capnography in addition to standard monitoring (pulse oximetry, blood pressure and cardiac monitoring) is more effective than standard monitoring alone to prevent cardiorespiratory adverse events (e.g. oxygen desaturation, hypotension, emesis, and pulmonary aspiration) in ED patients undergoing PSA.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (2016, Issue 8), and MEDLINE, Embase, and CINAHL to 9 August 2016 for randomized controlled trials (RCTs) and quasi-randomized trials of ED patients requiring PSA with no language restrictions. We searched meta-registries (,, and for ongoing trials (February 2016). We contacted the primary authors of included studies as well as scientific advisors of capnography device manufacturers to identify unpublished studies (February 2016). We handsearched conference abstracts of four organizations from 2010 to 2015.

Selection criteria: 

We included any RCT or quasi-randomized trial comparing capnography and standard monitoring to standard monitoring alone for ED patients requiring PSA.

Data collection and analysis: 

Two authors independently performed study selection, data extraction, and assessment of methodological quality for the 'Risk of bias' tables. An independent researcher extracted data for any included studies that our authors were involved in. We contacted authors of included studies for incomplete data when applicable. We used Review Manager 5 to combine data and calculate risk ratios (RR) and 95% confidence intervals (CI) using both random-effects and fixed-effect models.

Main results: 

We identified three trials (κ = 1.00) involving 1272 participants. Comparing the capnography group to the standard monitoring group, there were no differences in the rates of oxygen desaturation (RR 0.89, 95% CI 0.48 to 1.63; n = 1272, 3 trials; moderate quality evidence) and hypotension (RR 2.36, 95% CI 0.98 to 5.69; n = 986, 1 trial; moderate quality evidence). There was only one episode of emesis recorded without significant difference between the groups (RR 3.10, 95% CI 0.13 to 75.88, n = 986, 1 trial; moderate quality evidence). The quality of evidence for the primary outcomes was moderate with downgrades primarily due to heterogeneity and reporting bias.

There were no differences in the rate of airway interventions performed (RR 1.26, 95% CI 0.94 to 1.69; n = 1272, 3 trials; moderate quality evidence). In the subgroup analysis, we found a higher rate of airway interventions for adults in the capnography group (RR 1.44, 95% CI 1.16 to 1.79; n = 1118, 2 trials; moderate quality evidence) with a number needed to treat for an additional harmful outcome of 12. Although statistical heterogeneity was reduced, there was moderate quality of evidence due to outcome definition heterogeneity and limited reporting bias. None of the studies reported recovery time.