PuO2 in RenalGuard Pilot Study (PURE)

Effects on Urine Oxygenation of Forced Diuresis with Neutral Fluid Balance During Cardiac Surgery, a Randomized Controlled Trial

The PuO2 in RenalGuard (PURE) study is planned as a single center, randomized controlled pilot study comparing renal oxygenation during cardiac surgery with cardiopulmonary bypass (CPB) with or without balanced forced diuresis using the RenalGuard (RG) system.

Renal oxygenation will be assessed by urine oxygen tension, continuously measured by optodes placed through the urine catheter. Measurements will start after induction of anesthesia and continue for 24 hours.

In total, 30 patients will be randomized 1:1 to RG or standard of care (SOC) during cardiac surgery with CPB. In the RG group, the forced diuresis with neutral fluid balance will be maintained from before the start of surgery until 3 hours after weaning from CPB.

The primary endpoint is the group difference (RG vs SOC) in delta PuO2, defined as the change in mean PuO2 from baseline to the last 5-minute period at 45 minutes after start of CPB.

The secondary endpoints include

1. Group difference in mean PuO2 before, during and after CPB
2. Group difference in time weighted area under the curve for PuO2
3. Group differences in renal near infrared spectroscopy (NIRS) before, during and after CPB
4. Group difference in urine and blood biochemistry including renal biomarkers
5. Group difference in urine output and fluid balance during surgery and first postoperative day
6. Group differences in postoperative AKI according to the KDIGO criteria
7. Time (minutes) with puO2 ≤ 15 and ≤ 10 mmHg during and after CPB
8. Dynamics of PuO2 during the early postoperative phase

Patients ≥18 years scheduled for cardiac surgery with CPB with estimated glomerular filtration rate ≥50 ml/min are eligible for inclusion. Exclusion criteria include patients on higher doses of furosemide, patients with AKI or under renal replacement therapy.

Patients will be analyzed according to study group. In patients where hemofiltration has been used during CPB, control group patients who has received furosemide and patients in the RG group who do not reach target urine flow will be excluded from the main analysis but will be included in a separate analysis.

Study Overview

• Status: Not yet recruiting
• Conditions: Cardiac Surgery Subjects
• Intervention / Treatment: Device: RenalGuard Therapy

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Lukas Lannemyr Lannemyr, MD, PhD; Phone Number: 0046 708350971; Email: lukas.lannemyr@vgregion.se

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Patients ≥18 years of age
• scheduled for cardiac surgery with normothermic CPB
• Estimated glomerular filtration rate ≥50 ml/min as assessed by the CKD-EPI formula

Exclusion Criteria:

• Patient receiving furosemide at a dose>100 mg/day orally (or the equivalent dose of an alternative loop diuretic) in the last week
• Patient who cannot be urethrally catheterized for any reason
• Patient already dialysis dependent
• Known or suspected AKI (KDIGO criteria) at the time of screening
• Any condition which, in the judgement of the investigator, might increase the risk to the patient

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: RenalGuard (RG); The RG system is used to ensure neutral (0) fluid balance while maintaining a urine flow >200 ml/hour. Urine output is replaced 1:1 with Plasmolyte solution. In patients randomized to RG, therapy is initiated after baseline measurements but before the start of surgery. If baseline urine flow is < 200 ml/hour, a bolus dose of furosemide (20 mg iv) is given, and additional furosemide bolus and/or titration of continuous furosemide infusion may be given to maintain urine flow rate >200ml/hour. After completed surgery, RG therapy continues until 3 hours after weaning from CPB	Device: RenalGuard Therapy; Fluid management system, which weighs urine and controls intravenous administration of crystalloid solution.
No Intervention: Standard of Care; Conduct of cardiopulmonary bypass will be done according to local clinical practice

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Delta PuO2	The primary endpoint is the group difference (RG vs controls) in delta PuO2, defined as the change in mean PuO2 from baseline to the last 5-minute period at 45 minutes after start of cardiopulmonary bypass (CPB) (or the last 5 minutes if cross clamp release is done before)	Baseline (before start of surgery) to 45 minutes after start of CPB

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Repeated PuO2	Group difference in mean PuO2 at specified times	baseline, 30, 45 minutes on CPB and at 30, 60 and 240 minutes after CPB
PuO2 AUC	Group difference in time weighted area under the curve (AUC) for PuO2 during CPB and until removal of the PuO2 measurement	From baseline before start of surgery until 4 hours after CPB
PuO2 sub threshold	Time (minutes) with puO2 ≤ 15 and ≤ 10 mmHg during and after CPB	From baseline before surgery until 4 hours after CPB
Diuresis and fluid balance	Diuresis and net fluid balance (incorporating fluids given and lost) during surgery and during the first 24 hours.	24 hours

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dynamics of PuO2 during the early postoperative phase	Repeated measurements of PuO2 during the first postoperative 24 hours.	24 hours
Urine Nephrocheck	Urine IGFBP2*TIMP2 at 4 hours after Cardiac surgery	4 hours after CPB
Renal near-infrared spectroscopy (NIRS)	Group differences in renal NIRS at baseline, 30 minutes on CPB and at 30, 60 and 240 minutes after CPB	From baseline before surgery until 4 hours after CPB
Creatinine	Development of serum creatinine from baseline and daily for up to seven postoperative days	7 days

Collaborators and Investigators

• Sponsor: Sahlgrenska University Hospital
• Investigators: Principal Investigator: Lukas Lannemyr Lannemyr, MD, PhD, Institute of Clinical Sciences, Dept of Anesthesia and Intensive Care, Sahlgrenska Academy, Gothenburg University. Gothenburg, Sweden

Study record dates

Study Major Dates

• Study Start (Estimated): March 17, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: March 10, 2025
• First Submitted That Met QC Criteria: March 14, 2025
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: March 14, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: furosemide; renal oxygenation; urine oxygen tension; balanced diuresis
• Other Study ID Numbers: PUREstudy

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Parts of the data may be analyzed in other projects

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes