Respiratory support with nasal high flow without supplemental oxygen in patients undergoing endoscopic retrograde cholangiopancreatography under moderate sedation: a prospective, randomized, single-center clinical trial.

BACKGROUND: Nasal high flow (NHF) may reduce hypoxia and hypercapnia during an endoscopic retrograde cholangiopancreatography (ERCP) procedure under sedation. The authors tested a hypothesis that NHF with room air during ERCP may prevent intraoperative hypercapnia and hypoxemia. METHODS: In the prospective, open-label, single-center, clinical trial, 75 patients undergoing ERCP performed with moderate sedation were randomized to receive NHF with room air (40 to 60 L/min, n = 37) or low-flow O2 via a nasal cannula (1 to 2 L/min, n = 38) during the procedure. Transcutaneous CO2, peripheral arterial O2 saturation, a dose of administered sedative and analgesics were measured. RESULTS: The primary outcome was the incidence of marked hypercapnia during an ERCP procedure under sedation observed in 1 patient (2.7%) in the NHF group and in 7 patients (18.4%) in the LFO group; statistical significance was found in the risk difference (-15.7%, 95% CI -29.1 - -2.4, p = 0.021) but not in the risk ratio (0.15, 95% CI 0.02 - 1.13, p = 0.066). In secondary outcome analysis, the mean time-weighted total PtcCO2 was 47.2 mmHg in the NHF group and 48.2 mmHg in the LFO group, with no significant difference (-0.97, 95% CI -3.35 - 1.41, p = 0.421). The duration of hypercapnia did not differ markedly between the two groups either [median (range) in the NHF group: 7 (0 - 99); median (range) in the LFO group: 14.5 (0 - 206); p = 0.313] and the occurrence of hypoxemia during an ERCP procedure under sedation was observed in 3 patients (8.1%) in the NHF group and 2 patients (5.3%) in the LFO group, with no significant difference (p = 0.674). CONCLUSIONS: Respiratory support by NHF with room air did not reduce marked hypercapnia during ERCP under sedation relative to LFO. There was no significant difference in the occurrence of hypoxemia between the groups that may indicate an improvement of gas exchanges by NHF. TRIAL REGISTRATION: jRCTs072190021 . The full date of first registration on jRCT: August 26, 2019.

Fully covered metallic stents for anastomotic biliary strictures after living donor liver transplantation.

Objectives: Anastomotic biliary strictures (ABSs) are common complications following living donor liver transplantation (LDLT). We evaluated the feasibility of a novel removable, intraductal, fully covered, self-expandable metallic stent (FCSEMS) for the treatment of ABSs following LDLT. Methods: Nine patients with duct-to-duct ABSs that developed following LDLT were prospectively enrolled in this study. We placed a short FCSEMS with a long lasso and middle waist formation in each patient's ABS above the papilla and removed it 16 weeks later. Results: The FCSEMS placements were successful in all nine cases. Four patients experienced mild cholangitis, which was resolved with conservative treatment. Additionally, there was one case of distal migration. The FCSEMSs were successfully removed from all the patients, and the clinical success rate was 100%. Stricture recurrence occurred in one (11.1%) patient during the follow-up period. Limitations: The small number and lack of comparison with other types of FCSEMSs and plastic stents. Conclusions: Intraductal placement of FCSEMSs is useful for treating refractory ABSs after LDLT, although further studies are required with larger sample sizes.

Study on prevention of hypercapnia by nasal high flow in patients undergoing endoscopic retrograde cholangiopancreatography during intravenous anesthesia.

BACKGROUND: For relatively invasive upper gastrointestinal endoscopy procedures, such as an endoscopic retrograde cholangiopancreatography (ERCP), and also lower gastrointestinal endoscopy procedures, intravenous anesthesia is routinely used to reduce patient anxiety. However, with the use of intravenous anesthesia, even at mild to moderate depth of anesthesia, there is always a risk of upper airway obstruction due to a relaxation of the upper airway muscles.With the advent of nasal high flow (NHF) devices that allow humidified high flow air through the nasal cavity, can be used as a respiratory management method in the context of anesthesia. AIRVO is commonly used for patients with obstructive sleep apnea and other respiratory disorders. This device uses a mild positive pressure load (several cmH2O) that improves carbon dioxide (CO2) washout and reduces rebreathing to improve respiratory function and therefore is widely used to prevent hypoxemia and hypercapnia.This study aims to maintain upper airway patency by applying NHF with air (AIRVO) as a respiratory management method during intravenous anesthesia for patients undergoing an ERCP. In addition, this study investigates whether the use of an NHF device in this context can prevent intraoperative hypercapnia and hypoxemia. METHODS/DESIGN: This study design employed 2 groups of subjects. Both received intravenous anesthesia while undergoing an ERCP, and 1 group also used a concurrent nasal cannula NHF device. Here we examine if the use of an NHF device during intravenous anesthesia can prevent hypoxemia and hypercapnia, which could translate to improved anesthesia management.Efficacy endpoints were assessed using a transcutaneous CO2 monitor (TCM). This device measured the changes in CO2 concentration during treatment. Transcutaneous CO2 (PtcCO2) concentrations of 60 mm Hg or more (PaCO2 > 55 mm Hg) were considered marked hypercapnia. PtcCO2 concentrations of 50 to 60 mm Hg or more (equivalent to PaCO2 > 45 mm Hg) were considered moderate hypercapnia.Furthermore, the incidence of hypoxemia with a transcutaneous oxygen saturation value of 90% or less, and whether the use of NHF was effective in preventing this adverse clinical event were evaluated. DISCUSSION: The purpose of this study was to obtain evidence for the utility of NHF as a potential therapeutic device for patients undergoing an ERCP under sedation, assessed by determining if the incidence rates of hypercapnia and hypoxemia decreased in the NHF device group, compared to the control group that did not use this device. TRIAL REGISTRATION: The study was registered in the jRCTs 072190021.URL https://jrct.niph.go.jp/en-latest-detail/jRCTs072190021.