Utility of monitoring capnography, pulse oximetry, and vital signs in the detection of airway mishaps: A hyperoxemic animal model

doi:10.1016/S0735-6757(98)90125-5

The American Journal of Emergency Medicine

Volume 16, Issue 4, July 1998, Pages 350-352

https://doi.org/10.1016/S0735-6757(98)90125-5 Get rights and content

Abstract

This study was undertaken to determine the time interval for changes in end-tidal CO₂, oxygen saturation (Sao₂), heart rate (HR), and blood pressure (BP) in response to an acute airway obstruction or hypopharyngeal extubation in a hyperoxemic model. Complete and partial airway obstructions were simulated with complete and partial cross-clamping of an endotracheal (ET) tube in five anesthetized, nonparalyzed, mechanically ventilated Yorkshire minipigs with initial Pao₂ of >400 mm Hg. Placement of the ET tube into the hypopharynx was performed to simulate accidental extubation. Both sidestream (SS) and mainstream (MS) capnography were used. Continuous pulse oximetry monitored Sao₂, femoral arterial catheter monitored systolic BP, and electrocardiograph monitored HR. The time intervals for the capnograph wave to flatten and for the monitor to display zero were recorded after each airway alteration. The time interval to a change in the initial HR of 10 beats/min, a change of initial systolic BP of 10 mm Hg, and a change of initial Sao₂ of 5% were recorded. Experiments were carried out for 180 seconds, and 25 trials were performed. HR, systolic BP, and Sao₂ did not change for the 180-second duration of the trials. Complete obstruction produced a flattening of the SS and MS waveform in 8 ± 2 seconds and 6 ± 2 seconds, respectively. The SS and MS monitors displayed zero in 19 ± 1 seconds and 68 ± 7 seconds, respectively. Partial obstruction did not produce flattening of the wave or a monitor displaying zero. Hypopharyngeal extubation produced a flattening of the SS and MS waveform in 7 ± 1 seconds and 7 ± 2 seconds, respectively. The SS and MS monitors displayed zero in 18 ± 3 seconds and 76 ± 16 seconds, respectively. Continuous end-tidal CO₂ capnography detects acute airway obstruction and hypopharyngeal extubation more rapidly than does pulse oximetry or vital sign monitoring in a hyperoxemic porcine model.

References (9)

MS Bhende et al.
Validity of a disposable end-tidal CO₂ detector in verifying endotracheal tube position in infants and children
Ann Emerg Med
(1992)
I Murat et al.
Ventilatory response to carbon dioxide in children during nitrous oxide-halothane anaesthesia
Br J Anaesth
(1985)
H Owen et al.
Toward safer transport of sick and injured children
Anaesth Intens Care
(1983)
RK Kanter et al.
Adverse events during interhospital transport: Physiologic deterioration associated with pretransport severity of illness
Pediatrics
(1989)

There are more references available in the full text version of this article.

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Citation Excerpt :
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 [1–3].
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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.
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Supported by the Division of Emergency Medicine, Children's Hospital Medical Center, Cincinnati, OH.

Presented at The Pediatric Academic Societies Meeting, May 10, 1996, Washington, DC.

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Original contributionUtility of monitoring capnography, pulse oximetry, and vital signs in the detection of airway mishaps: A hyperoxemic animal model☆

Abstract

Ann Emerg Med

Br J Anaesth

Toward safer transport of sick and injured children

Anaesth Intens Care

Adverse events during interhospital transport: Physiologic deterioration associated with pretransport severity of illness

Pediatrics

Original contribution
Utility of monitoring capnography, pulse oximetry, and vital signs in the detection of airway mishaps: A hyperoxemic animal model☆