Postoperative High-flow Nasal Oxygenation After High-risk Surgery in the Frail Adult (Hi-POP)

High flow nasal oxygen (HFNO) in the immediate postoperative period has been demonstrated to reduce the risk of postoperative pulmonary complications (PPC) after cardiothoracic surgery. In specific groups of patients such as the obese and after upper abdominal surgery the results are contradictive. However, there is lack of evidence if HFNO in the general high-risk patient after abdominal and non-cardiac thoracic surgery can reduce the prevalence of PPC, hypoxaemia and escalation of therapy. Therefore, the investigators aim to compare the use of HFNO with conventional oxygen therapy (COT) in high-risk patients after abdominal and non-cardiac thoracic surgery regarding postoperative pulmonary complications.

Study Overview

• Status: Recruiting
• Conditions: Postoperative Pulmonary Complications (PPCs)
• Intervention / Treatment: Combination product: High Flow Oxygen; Combination product: Oxygen

• Study Type: Interventional
• Enrollment (Estimated): 200
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Ida-Maria Forsberg, PhD; Phone Number: +46704381445; Email: ida-maria.forsberg@regionstockholm.se

Study Locations

• Sweden
  • Stockholm, Sweden
    • Recruiting
    • Karolinska university Hospital
    • Contact: Ida-Maria Forsberg, Consultant, PhD; Phone Number: + 46 8 5177 0000; Email: ida-maria.forsberg@regionstockholm.se

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Adults (≥18 years old) scheduled for elective abdominal (laparotomy or laparoscopy), open abdominal vascular or non-cardiac thoracic surgery under general anaesthesia with an estimated duration over 3 hours.

AND

Meeting at least two of the following criteria:

• Age > 65 years
• BMI >30
• Preoperative SpO2 <95 %
• Scheduled for lobectomy or pulmonary segment resection
• Respiratory tract infection the last month
• Preoperative anaemia (Hb <100) or severe hypoalbuminemia (<20 g/L)
• Current smoker or previous smoker with >30 packyears
• Pulmonary disease or OSAS
• Heart failure
• Clinical frailty (CFS 4)

Exclusion Criteria:

• Not suitable for postoperative HFNO, as decided by a study member or the anaesthetist in charge (such as total nasal obstruction, skull fracture, facial injuries)
• Pregnancy
• Not able to understand the study information or sign an informed consent.
• Not able to participate with the treatment postoperatively
• Planned for delayed extubation in the intensive care
• Preoperative non-invasive ventilation due to respiratory failure or a higher level of care than a regular ward

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: HFNO; Group of patients receiving HFNO postoperatively	Combination product: High Flow Oxygen; High flow nasal oxygen will be administered in the intervention group
Active Comparator: Conventional oxygen therapy (COT); Group of patients receiving conventional oxygen therapy postoperatively	Combination product: Oxygen; Oxygen delivered by nasal cannula or oxymask

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Frequency of postoperative pulmonary complications (PPC) the first seven days after high-risk abdominal or non-cardiac thoracic surgery in high-risk patients with high-flow nasal oxygen or conventional oxygen therapy in the immediate postoperative period	Up to 7 days after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Lowest SpO2 the first 2 and 24 h after randomisation	Lowest oxygen saturation registered in the chart during the first 2 and 24 h after randomisation	24 hours after randomisation
Desaturation (SpO2 <90%) the first 2 or 4 and under 24 hours after randomisation	Proportion of patients that has a registered oxygen saturation under 90% 2, 4 and 24 hours after randomisation	First 24 hours after randomisation
Lowest PaO2/FiO2 ratio during the intervention period	Comparison of the lowest PaO2 and FiO2 (fraction of inspired oxygen) during the intervention period ( i e 2 or 4 hours depending of the result from the air test)	Maximum 4 hours after start of intervention postoperatively
Subjective patient comfort (visual scale 0-10)	Patients will report their comfort with each method, HFNO or COT after the intervention	Maximum 4 hours after start of intervention
Length of stay (LOS) in the postoperative unit	The duration of stay in the postoperative unit will be registered and compared between the groups	Up to 7 days after surgery
Length of stay in hospital	The length of stay in hospital after surgery will be recorded and compared	From surgery up until 30 days after surgery
Mortality in hospital	Mortality during hospital admission after surgery	Up until 30 days after surgery
30-days mortality	30-days mortality, number and proportion of patients between the groups	30 days after surgery
Healthy days at home 30 days after surgery	Number of healthy days at home 30 days after surgery compared between the groups	30 days postoperatively

Collaborators and Investigators

• Sponsor: Region Stockholm
• Collaborators: Karolinska Institutet

Study record dates

Study Major Dates

• Study Start (Actual): April 20, 2026
• Primary Completion (Estimated): March 9, 2028
• Study Completion (Estimated): March 9, 2029

Study Registration Dates

• First Submitted: February 19, 2026
• First Submitted That Met QC Criteria: March 9, 2026
• First Posted (Actual): March 11, 2026

Study Record Updates

• Last Update Posted (Actual): May 14, 2026
• Last Update Submitted That Met QC Criteria: May 11, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: High flow nasal oxygen; HFNO; Postoperative pulmonary complication
• Additional Relevant MeSH Terms: Inorganic Chemicals; Elements; Chalcogens; Gases; Oxygen
• Other Study ID Numbers: 2026-00273-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No