Sedation spectrum in endoscopic retrograde cholangiopancreatography: Continuous adaptation is the way forward.

In the modern era, endoscopic retrograde cholangiopancreatography (ERCP) is routinely performed in any gastroenterology endoscopic setup and it is valuable in diagnosing various biliary and pancreatic conditions. The therapeutic indications of ERCP include stone extraction from the bile duct and stenting of biliary or pancreatic duct.[1] Laparoscopic choledochotomy and magnetic resonance cholangiopancreatography are slowly but surely replacing ERCP in some situations.[2]

Patients undergoing ERCP generally belong to the high-risk group. Besides advanced age, they frequently have associated medical conditions such as cardiac issues and diabetes. Sedation in these patients in prone or semi-prone position with minimal respiratory assistance is a challenge in itself. Adequate sedation, patient cooperation, and an immobile patient is the mainstay for the successful outcome of an ERCP procedure. Sedation is a continuum and deeper planes sometimes lead to desaturation requiring ventilatory support.

Various sedatives and narcotics are used to anesthetize the patients undergoing ERCP. Propofol in bolus doses or a continuous infusion forms the backbone of various sedation protocols. It has a short half-life and exhibits a dose dependent activity. Chen et al.[3] reported that propofol provided superior patient cooperation thus reducing the procedure duration. Opioids along with midazolam have also been found to provide satisfactory sedation.[4] Among various drugs used for sedation, propofol has been reported to have faster recovery times and a lower incidence of post-procedural hypoxemia.[5]

In the present issue of this journal, Goudra et al. have published a study on the anesthetic management of patients undergoing ERCP.[6] A review of 653 patients has been presented, describing the anesthesia practice. At induction, patients are ventilated with 100% oxygen through mapleson C breathing system, with a tightly held inflatable face mask at a flow rate of 12-15 L/min. Any breath holding because of propofol bolus is concurrently managed. Further, during this period the nasal trumpet and the gastroscope are also introduced. This novel concept of ventilation tides over any initial apneic spells.

Induction is carried out with boluses of propofol and fentanyl until adequate jaw relaxation is achieved. Propofol infusion is used for maintenance hence, avoiding sudden increase in plasma propofol levels due to boluses, which may lead to apnea. Respiratory monitoring is carried out with EtCO2, impedance pneumogram, and visualization of chest excursions. Though, 60% of the patients in their study group were American Society of Anaesthesiologists grade III/IV, emergency intubation or disruption of procedure was never required. Further, they found no correlation between Mallampati grade or body mass index and increased incidence of intubation. Periods of desaturation were managed with assisted breaths from the mapleson circuit attached to a nasal trumpet or other airway conduit.

The incidence of cardiopulmonary complications has been reported to be 0.01-5.4/1000 endoscopic procedures.[7] General anesthesia is often preferred in some cardiac patients where hypoxia coupled with hypotension can be catastrophic. This article has delineated how to maintain airway patency using different devices and to swiftly tackle respiratory depression. Endoscopic suites can incorporate some of these techniques in their setup and ascertain whether there is definite reduction in incidence of desaturation and the number of cases requiring general anesthesia. However, some factors like patient cooperation, endoscopist's preference and duration of ERCP vary from center-to-center and are vital in defining the anesthesia protocol. The study could have been strengthened by discussing the hemodynamic parameters, which are of vital importance in ASA grade III and IV patients.