Letters to the Editor
We thank Dr Sarkiss for her interest in our article,1 and the capnography. We have intentionally omitted from the original article some technical aspects of capnography monitoring due to word limit, keeping it as concise of an overview as possible. We appreciate this opportunity to highlight these issues.
Indeed there are some limitations to the use of capnography monitors. Dr Sarkiss has detailed potential limitations of 1 type of capnography monitoring cannula especially during the bronchoscopy. Incidentally, there are many different types of capnography cannulas available on the market. We share a picture of one where both the oxygen and the capnography limbs of the cannula are designed to serve both nostrils (Fig. 1). Such a design can be helpful during the bronchoscopy. There also exists a design that includes an oral limb for the mouth breathers. In our opinion, bronchoscopists should pick and choose the design that would work best for their patients.
Capnography recording might be interrupted by other factors such as sample line kink, accumulation of moisture in the line, or by loss of tidal volume through suctioning as explained by Dr Sarkiss. However, suctioning is not usually a continuous process, and neither losing the capnography wave form during the very brief seconds of suctioning nor for the other reasons mentioned above should deter bronchoscopists from using capnography during bronchoscopy.
The purpose of capnography is to attract more attention toward respiratory monitoring during conscious sedation. If a disordered breathing/apnea wave form is observed during the procedure, the bronchoscopy team can promptly evaluate the patient for any need for intervention and to rule out waveform artifacts. If artifacts are encountered too frequently, then a proper securing of the cannula, a change in the design of the cannula, and/or a better moisture trap might be required to avoid alarm fatigue.
That said, we totally agree with Dr Sarkiss that before any major practice change is contemplated in monitoring the patient, a thorough analysis of the newer technology related to its cost-effectiveness, accuracy, and risk/benefit ratio should be carried out. Indeed, that is what has taken place among the stake holders of the anesthesiology and other subspecialty societies.2–6 These organizations have either already adopted or strongly supported such monitoring practice. In our opinion, time has come for the bronchoscopy community to consider subscribing to capnography monitoring.
Basem Abdelmalak, MD*
Juan Wang, MD†
Atul C. Mehta, MD, FACP, FCCP‡
*Center for Sedation, Anesthesiology Institute, Cleveland Clinic
‡Respiratory Institute, Cleveland Clinic, Cleveland, OH
†Department of Pulmonary Diseases, Beijing Tian Tan Hospital, Capital Medical University, Beijing, China
1. Abdelmalak B, Wang J, Mehta A. Capnography monitoring in procedural sedation for bronchoscopy. J Bronchol Interv Pulmonol. 2014;21:188–191.
4. Merchant R, Chartrand D, Dain S, et al.. Guidelines to the practice of anesthesia revised edition 2012. Can J Anaesth. 2012;59:63–102.
5. Baerlocher MO, Nikolic B, Silberzweig JE, et al.. Society of Interventional Radiology position statement on recent change to the ASA’s moderate sedation standards: capnography. J Vasc Interv Radiol. 2013;24:939–940.