This prospective, single-centre, randomized controlled trial evaluates whether high-flow nasal oxygen (HFNO) reduces hypoxaemia compared with conventional low-flow oxygen therapy (COT) during endoscopic retrograde cholangiopancreatography (ERCP) performed under sedation in geriatric and adult patients.

One hundred ASA I-III patients undergoing ERCP were stratified by age (<65 and ≥65 years) and randomized to receive HFNO or COT. The primary outcome is the incidence of hypoxaemia (SpO₂ ≤90%). Secondary outcomes include hypotension, haemodynamic changes, sedative consumption, and recovery time.

Endoscopic retrograde cholangiopancreatography (ERCP) is a complex gastrointestinal endoscopic procedure frequently performed under deep sedation. Due to the prone position, prolonged procedural duration, and sedative-induced respiratory depression, ERCP is associated with an increased risk of cardiopulmonary complications, particularly hypoxaemia and haemodynamic instability. These risks are more pronounced in geriatric patients because of age-related reductions in respiratory reserve, impaired ventilatory response to hypercapnia, and diminished cardiovascular compensatory mechanisms.

Conventional oxygen therapy (COT) delivered via low-flow nasal cannula is routinely used during sedated ERCP. However, low-flow systems may provide inconsistent inspired oxygen concentrations and do not generate positive airway pressure. High-flow nasal oxygen (HFNO) delivers heated and humidified oxygen at high flow rates, allowing for stable fractional inspired oxygen (FiO₂) delivery, nasopharyngeal dead space washout, and generation of a low level of positive end-expiratory pressure (PEEP). These physiological effects may improve oxygenation and reduce hypoxaemic events during procedural sedation.

The present study was designed as a prospective, single-centre, age-stratified, parallel-group randomized controlled trial to compare HFNO and COT in adult (<65 years) and geriatric (≥65 years) patients undergoing ERCP under sedation.

A total of 100 ASA physical status I-III patients scheduled for ERCP were enrolled. Patients were stratified by age and randomized in a 1:1 ratio within each stratum to receive either HFNO or COT, resulting in four groups:

Adult + HFNO Geriatric + HFNO Adult + COT Geriatric + COT Sedation was standardized across groups. All patients received pre-procedural midazolam and topical lidocaine anesthesia. Sedoanalgesia was achieved using fentanyl and propofol, followed by maintenance with a ketofol infusion (ketamine-propofol mixture). Drug dosages were adjusted according to age and clinical response. Standard intra-procedural monitoring included heart rate, non-invasive blood pressure, peripheral oxygen saturation (SpO₂), and end-tidal carbon dioxide (EtCO₂).

HFNO was delivered at a flow rate of 50 L/min with FiO₂ of 0.50 and temperature of 37°C. In cases of desaturation, flow was increased up to 60 L/min and FiO₂ up to 100% if required. Conventional oxygen therapy consisted of 4 L/min oxygen via nasal cannula.

Inclusion Criteria:

• Age ≥18 years
• Patients scheduled for elective endoscopic retrograde cholangiopancreatography (ERCP)
• Planned sedation with monitored anesthesia care
• ASA physical status I-III
• Ability to provide written informed consent
• Adult group: 18-64 years
• Geriatric group: ≥65 years

Exclusion Criteria:

• Severe cardiac, pulmonary, renal, neurological, or hepatic disease
• Baseline hypotension (systolic arterial pressure <90 mmHg) or uncontrolled hypertension (systolic arterial pressure >170 mmHg, diastolic pressure >100 mmHg)
• Pre-existing hypoxaemia (SpO₂ <90%)
• Known hypersensitivity to study medications or a history of sedation-related adverse events
• Use of sedative medication within 24 hours prior to the procedure
• Refusal to participate