Capnography during conscious or procedural sedation -What is the present concern?

    Bhavani Shankar Kodali MD  

 

Propofol and other sedatives, although administered in good faith to produce conscious or light sedation, can often result in inadvertent deep sedation comparable to general anesthesia.(1,2) in a study by Ramsay etal, the authors observed that 74% of their patients crossed into general anesthesia as indicated by patient state index levels (PSI) below 70 measure by PSA 4000 that measures sedation depth. This can result in putting patients at significant risk for possible complications that includes respiratory depression. Therefore, it is rational, or even may be mandatory, to monitor oxygenation and ventilation. Since hypoventilation, airway obstruction and apnea precede the actual development of hypoxia, capnography plays a significant role in detecting these precursors. This enables corrective measures to be initiated and thus avoiding hypoxia.  There is considerable debate in the literature regarding the safety of propofol administration outside of the operating rooms for sedation  Some consider it is safe, whereas others think it is not. These concerns are illustrated  in a debate in the American Journal of Gastroenterology. (3) Under these circumstances, it is wise to monitor ventilation and oxygenation as adequately as one can, and also be proficiently trained in taking care of sedated patients.

Hypoventilation and apnea generally occur before hypoxia

 

 

Capnography helps to facilitate identification of apnea and enable corrective measures to be instituted

 

 

1 Ramsay E etal. ASA Annual Meeting 2004. Abstract - A 68.

2. Nurse administered propofol puts patients at risk. Anesthesiology News 2005;31:3:1.

3. Debate on the use of propofol by Non anesthesiologists. Am J Gastroenterology 2004;99:7:1207-11