Original Contribution
A randomized controlled trial of capnography during sedation in a pediatric emergency setting☆,☆☆,★

https://doi.org/10.1016/j.ajem.2014.09.050Get rights and content

Abstract

Objective

Data suggest that capnography is a more sensitive measure of ventilation than standard modalities and detects respiratory depression before hypoxemia occurs. We sought to determine if adding capnography to standard monitoring during sedation of children increased the frequency of interventions for hypoventilation, and whether these interventions would decrease the frequency of oxygen desaturations.

Methods

We enrolled 154 children receiving procedural sedation in a pediatric emergency department. All subjects received standard monitoring and capnography, but were randomized to whether staff could view the capnography monitor (intervention) or were blinded to it (controls). Primary outcome were the rate of interventions provided by staff for hypoventilation and the rate of oxygen desaturation less than 95%.

Results

Seventy-seven children were randomized to each group. Forty-five percent had at least 1 episode of hypoventilation. The rate of hypoventilation per minute was significantly higher among controls (7.1% vs 1.0%, P = .008). There were significantly fewer interventions in the intervention group than in the control group (odds ratio, 0.25; 95% confidence interval [CI], 0.13-0.50). Interventions were more likely to occur contemporaneously with hypoventilation in the intervention group (2.26; 95% CI, 1.34-3.81). Interventions not in time with hypoventilation were associated with higher odds of oxygen desaturation less than 95% (odds ratio, 5.31; 95% CI, 2.76-10.22).

Conclusion

Hypoventilation is common during sedation of pediatric emergency department patients. This can be difficult to detect by current monitoring methods other than capnography. Providers with access to capnography provided fewer but more timely interventions for hypoventilation. This led to fewer episodes of hypoventilation and of oxygen desaturation.

Introduction

Capnography, or continuous end-tidal carbon dioxide (ETCO2) monitoring, is a sensitive indicator of ventilation that can alert a provider to hypoventilation more often and earlier than other modalities [1], [2], [3]. In nonintubated patients, it is measured passively via a nasal-oral cannula in a continuous and objective manner [4], [5]. Capnography can detect hypoventilation and apnea before it becomes apparent by clinical examination or pulse oximetry, yet is infrequently used in monitoring children during sedation in an outpatient or pediatric emergency department (PED) setting despite promotion by agencies such as the Joint Commission [2], [6], [7], [8], [9], [10], [11], [12], [13]. The detection of apnea or hypoventilation can be significantly delayed by use of pulse oximetry alone, particularly if patients receive supplemental oxygen [1], [14], [15], [16], [17], [18].

Children in the PED frequently need medications for procedural sedation, which induces a state of attenuated pain, anxiety and motion to facilitate procedures such as fracture reduction or drainage of abscesses [19], [20], [21]. Although sedation is generally safe, it may lead to hypoventilation due to alterations in a patient's respiratory rate or tidal volume. Although the normal respiratory rate varies by age, providers may follow trends with impedance plethysmography or clinical examination. However, tidal volume is less easy to quantify. Hypopnea, a decline in tidal volume, is not detectable by monitoring either respiratory rate or other standard parameters and is difficult to detect on physical examination. However, hypopnea commonly occurs during sedation and often precedes hypoxemia [2], [7], [22], [23].

This is the first randomized trial to examine the effects of capnography on detecting hypoventilation and preventing hypoxemia during sedation among children in the PED. We hypothesized that the addition of capnography to standard monitoring would significantly improve recognition of hypoventilation by providers caring for sedated children. This improved recognition might increase the rate of interventions to prevent continued hypoventilation and reduce the rate of oxygen desaturations, thus improving patient safety.

Section snippets

Study design and setting

This was a randomized, controlled trial of capnography in a PED within an urban, tertiary care academic center from September 1, 2011, to January 31, 2013. The PED is staffed by 13 pediatric emergency medicine attendings, 6 fellows, and approximately 50 registered nurses.

Population

Children aged 1 to 20 years given intravenous medications to induce sedation were eligible for inclusion. Exclusion criteria included intubation, administration of baseline supplemental oxygen without preceding hypoxemia, and

Results

There were 194 children approached for enrollment. Twenty-seven potential subjects were excluded: 18 refused to participate, 4 were not sedated or study personnel were unavailable, 3 did not tolerate the cannula, and cannula interfered with the procedure in 2 (eg, nasal laceration). Thirteen patients were excluded after randomization (7 controls, 6 cases): 11 for crying during greater than 20% of the sedation, 1 was younger than 1 year, and 1 used a pacifier which obstructed the cannula.

Discussion

This is the first randomized trial in children to assess the impact of the addition of capnography to standard monitoring during sedation in a PED. We found that capnography benefited patients by reducing the rate of hypoventilation in subjects over time, improving the timeliness of interventions, and impacting the frequency of oxygen desaturations when timely interventions were performed.

It is important to note that all episodes of hypoventilation in this study were caused by hypopnea. The low

Limitations

There are several potential limitations to our study. Our primary outcome was a pulse oximetry reading less than 95%, with a reading less than 90% as a secondary measure. Although the direct patient morbidity associated with oxygen desaturations is unknown, the administration of supplemental oxygen without the ability to continuously monitor a patient's ventilatory status can mask continued respiratory depression and can lead to respiratory arrest. Similarly, a consensus panel on pediatric

Conclusions

In summary, hypopneic hypoventilation is common among children receiving sedation in a PED and is difficult to detect other than by capnography. Providers with access to capnography during sedation provided fewer, but more timely interventions for hypoventilation. This was associated with fewer episodes of hypoventilation and fewer episodes of oxygen desaturation. Although larger studies are needed to assess the impact of capnography on more serious adverse events, capnography may improve the

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    ☆

    Source of support: This publication was made possible, in part, by Clinical and Translational Science Award Grant Nos. UL1 TR000142 and KL2 TR000140 from the National Center for Advancing Translational Science, components of the National Institutes of Health (NIH), and NIH roadmap for Medical Research. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NIH.

    ☆☆

    Clinical Trials Registration: Name: Using Capnography to Reduce Hypoxia During Pediatric Sedation, Registration No: NCT01463527.

    ★

    Presentations: Data were presented from this study in platform format at both the Eastern Society of Pediatric Research in Philadelphia, PA, March 2013, and the Pediatric Academic Society meeting in Washington, DC, May 2013.

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