EtCO2 Monitoring for procedural sedation

21 Aug

Potential complications of procedural sedation include hypoventilation, aspiration, and respiratory failure capnowith hypoxic brain injury.

Capnography -> the non-invasive measurement of the partial pressure of carbon dioxide in exhaled breath.

Capnometer -> a device that displays what numeric value for end tidal carbon dioxide (ETCO2).

 

Hypoventilation always precedes hypoxia during procedural sedation, either due to airway obstruction or diminished respiratory drive.

ETCO2 monitoring provides an early warning signal to provide time to intervene before the onset of hypoxia.

 

The evidence:

132 subjects undergoing procedural sedation with Propofol (1 mg/kg then 0.5 mg/kg boluses using ideal body weight) were randomized to intervention (standard monitoring + capnography measuring ETCO2 via nasal cannula using the Capnostream 20™) or control (standard monitoring alone) groups.

All patients received 3L/minute oxygen and 0.5 μg/kg fentanyl or 0.05 mg/kg of morphine at least 30-minutes prior to the procedure.

The primary outcome was hypoxia, as defined by an oximetry reading of ≤ 93%. Respiratory depression was defined as ETCO2 ≥ 50 mm Hg, an absolute increase or decrease from baseline ETCO2 ≥ 10%, or loss of the waveform for > 15 seconds.

Capnography-defined respiratory depression was 100% sensitive and 64% specific in predicting hypoxia with the loss of a waveform being the most likely finding to precede hypoxia.

In patients with hypoxia, the median time from onset of respiratory depression to hypoxia was 60 seconds (range 5 to 240 seconds). 



 

A few things to consider:

-insufficient demographic variables were identified (history of obstructive sleep apnea, comorbidities, etc.)

-the Capnostream 20™ costs $4,950 per unit

 

Submitted by Kelly Estes.

 

Reference: Dietch K, Miner J, Chudnofsky CR, et al. Does end tidal CO2 monitoring during emergency department sedation and analgesia with Propofol decrease the incidence of hypoxic events? A randomized, controlled trial. Ann Emerg Med 2010; 55: 258-264.

Picture: covidien.com

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