Adverse events with non-anesthesiologist administration of propofol: what you see is what you get but getting (the right standard monitors) is how you see

We congratulate Dumonceau et al. on their recently published guideline on non-anesthesiologist administration of propofol for gastrointestinal (GI) endoscopy [1]. This is a well-crafted treatise with excellent current literature references that support their statements and recommendations.

We would like to recommend a much stronger emphasis on ventilation monitoring for the next iteration of their guideline: from “consideration of capnography” to, instead, its requirement. Propofol exhibits a narrow therapeutic window for moderate to deep sedation to general anesthesia, and there is patient intervariability in terms of dose-related effects on respiratory drive. Safe use requires provider training, experience, and attention to objective real-time data from patient monitors. Dominceau et al. cite references that document safe use of propofol for endoscopic sedation without capnography, and some (Swiss and German) without routine blood pressure or electrocardiographic (ECG) monitors. Yet other European papers [2,3] suggest that serious, preventable anesthetic complications go significantly underreported.

Our American experience provides insight into such higher potential risk of adverse events with propofol sedation for endoscopy when ventilation monitoring is not used. A study of the American Society of Anesthesiology Closed Claims Database confirmed that respiratory complications, specifically inadequate oxygenation and ventilation, occurred at nearly twice the rate in nonoperating room (NORA) locations, which include GI endoscopy, as it did in the main operating room where capnography is absolutely mandatory [4]. The GI suite was the source of 32 % of all NORA claims. The margin by which injury was considered preventable was 4:1 comparing NORA with the operating room, with deficiencies in pulse oximetry and/or capnography monitoring cited [4]. As NORA malpractice monetary awards in the USA run to double those of the main operating room, capnography seems to be a wise investment. With regard to European endoscopy practices that choose to forego blood pressure and/or ECG monitors for their propofol-sedated endoscopy patients, the acquisition and use of capnography monitoring would provide beneficial information about the adequacy of their patients’ blood pressure and cardiac output.

For endoscopy practices with insufficient resources to invest in capnography monitors, we strongly counsel strict avoidance of supplemental oxygen. It is well proven that supplemental oxygen can mislead the practitioner by supporting excellent pulse oximetry saturation readings in the absence of effective ventilation [5]. As little as 2 L/min of nasal cannula oxygen flow maintains high oxygen saturation in the presence of dangerous levels of arterial carbon dioxide and significant respiratory acidosis. When using room air instead, the pulse oximeter becomes a much more sensitive and reliable indicator of hypoventilation [5].

In summary, we would strongly encourage routine use of capnography in all cases of non-anesthesiologist administration of propofol for GI endoscopy. We advocate the same standard for anesthesiologist-administered propofol. In situations where capnography is not available, the use of continuous supplemental oxygen should be discouraged because it can conceal significant compromise in ventilation.

• References

• 1 Dumonceau JM, Riphaus A, Schreiber F et al. Non-anesthesiologist administration of propofol for gastrointestinal endoscopy: European Society of Gastrointestinal Endoscopy, European Society of Gastroenterology and Endoscopy Nurses and Associates Guideline – Updated June 2015. Endoscopy 2015; 47: 1175-1189
• 2 Hove L, Christoffersen J. Closed claims from Switzerland: an important contribution to improving patient safety in anaesthesia. Eur J Anaesthesiol 2011; 28: 77
• 3 Cook T, Bland L, Miahi R et al. Litigation related to anaesthesia: an analysis of claims against the NHS in England 1995–2007. Anaesthesia 2009; 64: 706-718
• 4 Metzner J, Posner K, Lam M et al. The risk and safety of anesthesia at remote locations: the US closed claims analysis. Curr Opin Anaesthesiol 2009; 22: 502-508
• 5 Fu E, Downs J, Schweiger J et al. Supplemental oxygen impairs detection of hypoventilation by pulse oximetry. Chest 2004; 126: 1552-1558