Presently, gastrointestinal endoscopic procedures (GIEPs) are mostly performed under sedation. In a few patients, general anaesthesia remains necessary due to procedure invasiveness or patient characteristics.[1,2] Benzodiazepines combined with opioids, usually referred to as traditional sedative agents, are widely used for sedation by anaesthesia care providers and gastroenterologists in the US and elsewhere. However, randomised studies have evaluated pharmacological alternatives for procedural sedation and have shown that propofol (Baxter International Inc., Deerfield, IL), compared with the use of traditional agents, has a rapid onset of action, provides predictable sedation depth and recovery times, and improves patient satisfaction rates.[4–6] Nonetheless, and despite its beneficial pharmacokinetic profile, propofol has a narrow therapeutic window and no antidote, highlighting the fact that it should be administered by certified health professionals using precise administration techniques to avoid critical events.
Worldwide, the safety profiles of different models of propofol administration have been analysed, such as nurse- and gastroenterologist-performed sedation, patient-controlled and computer-assisted methods, and anaesthetist-managed propofol sedation using intermittent boluses.[8–10] Among the studied models, propofol administration using target-controlled infusion (TCI) systems is emerging as an attractive alternative for anaesthetist-managed sedation. The current propofol TCI systems are pre-programmed with the Marsh and Schnider pharmacokinetic models. The rate constants in the Marsh model are fixed, whereas compartment volumes and clearances are weight proportionally; the Schnider model has several fixed values, whereas others are adjusted according to total weight, lean body mass, and height. One major benefit of the Schnider model is that it adjusts the doses and infusion rates according to patient age. Through the use of microprocessor-controlled infusion pumps, the infusion rate is dynamically titrated to achieve plasmatic or effect site 'targeted' concentrations. Over the past 5 years at our institution most gastrointestinal endoscopies have been performed under propofol TCI sedation administered by anaesthetists. Although this technique has proven to be effective, few investigations have reported the incidence of unplanned cardiovascular and respiratory adverse events during anaesthetist-managed propofol TCI sedation for GIEPs. Therefore, sufficient evidence for improved safety over other anaesthetic strategies is lacking.
The primary aim of this historical cohort study was to describe the incidence of significant adverse events (cardiovascular and respiratory) in adult patients scheduled for elective outpatient GIEPs under anaesthetist-performed propofol TCI sedation and nasal cannula oxygenation. The secondary aim was to investigate associations between hypotension and oxygen desaturation events and potentially related variables (procedure type and duration, opioid administration, and total propofol dose among others) through multivariate analysis.
BMC Anesthesiol. 2020;20(195) © 2020 BioMed Central, Ltd.