Detecting Tissue Ischemia in Reconstruction Flaps by a Novel CO2 Biosensor (DIMENSION-study) (DIMENSION)

Detecting Tissue Ischemia in Reconstruction Flaps by a Novel CO2 Biosensor (DIMENSION-study); An Open, Prospective, Intervention Study

The investigators will test if changes in CO2 is detected postoperatively in ischemic tissue in a reconstructed flap.

IscAlert is measuring continuously CO2 in muscular and subcutaneous tissue. IscAlert is inserted distal to the operative field into normal muscle and/or subcutaneous tissue in the reconstructed flap. Local tissue CO2 and temperature will be monitored continuously postoperatively until maximal 10 days.

If a reduced or totally obstructed blood flow appear (thrombosis), an increase in tissue CO2 and a lower local temperature will emerge rapidly as a sign of ischemia. This will be detected by the sensor which will alarm the investigators.

This will lead to assessment of the reconstructed flap and if restricted blood flow is diagnosed, a reoperation or other intervention will be performed. 56 patients will be enrolled to undergo the procedures. The IscAlert will be removed from the patient before the patient is discharged from the hospital or a maximum of 10 days (the event that occurs first). 360 devices are planned to be used in this clinical study.

Study Overview

• Status: Active, not recruiting
• Conditions: Ischemia; Surgery; Blood Circulation Disorder; Biosensing Techniques
• Intervention / Treatment: Device: IscAlert

Detailed Description

This is an open, prospective, interventional, single-center clinical investigation designed to examine the feasibility and safety of the IscAlert™ device in patients scheduled for reconstructive flap surgery. 56 will be enrolled to undergo the procedures using a total of 350 devices depending on the injuries. IscAlert is 0.8 mm in diameter and in vitro testing, shows stable and accurate measurements of pCO2. More than 200 animal experiments have been done with the sensor. The experiments have shown that the sensor detects ischemia (Increased CO2-measurements) in real time in the following organs and tissues: Brain, heart, liver, kidneys, pancreas, intestines, musculature and subcutaneous tissue. Sensitivity and specificity are close to 100%. The sensors are inserted into tissue by a split needle technique. The split needle is the size of a 3-gauge peripheral venous catheter. In animal studies, no complications have been detected when using the sensor. The IscAlert sensors are connected to an electronics unit that is fixed to the skin with an adhesive plaster or glue outside the sterile area. The electrical signals are redirected to a PC approved for clinical use which continuously records tissue pressures of CO2. IscAlert is inserted into normal muscle and/or subcutaneous tissue distal on the reconstructed flap to be operated at the end of surgery. The insertion is far away from the operating field. The insertion is done under sterile conditions in accordance with standard sterility criteria at the hospital. No pain during insertion will occur because of insertion is performed during general anesthesia. Also, the insertion can be compared to an intramuscular injection. Postoperatively, the IscAlert sensor will continuously monitoring tissue CO2 and temperature. If ischemia occur, for examples caused by a thrombus, an increase in tissue CO2 and a lower temperature will evolve. This will be detected by the sensor which will alarm the investigators. This will lead to assessment of the reconstructed flap and if restricted blood flow is diagnosed, a reoperation or other intervention will be performed. The IscAlert will be removed from the patient before the patient is discharged from the hospital or a maximum of 10 days (the event that occurs first). Approximately 360 devices are planned to be used in this clinical study. One of the sensors will be used as a control inserted into neighboring tissue.

The primary objective is to compare CO2-levels in the reconstructed flap in individuals who has undergone reconstructed flap surgery and investigate if CO2-level is different in patient diagnosed with obstructed blood flow vs. patients with sufficient blood flow in the reconstructed flap.

Our hypotheses are:

1. The IscAlert™ device will be able to detect the presence of ischemia in the reconstructed flap by increased pCO2 levels and decrease in tissue temperature, measured by IscAlert™.
2. By using the IscAlert™ device monitoring ischemic events, an early treatment for ischemia could lead to higher incidence of reconstructed flap survival rates, and less revision surgery caused by thrombosis.
3. No clinically significant bleeding or infection will occur using IscAlert™ in this clinical study.

• Study Type: Interventional
• Enrollment (Estimated): 160
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Norway
  • Oslo, Norway, 0424
    • Oslo University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients must be scheduled for reconstructive flap surgery
• surgery
• Patients must be ≥ 18 years
• Patients must be able to give written signed informed consent

Exclusion Criteria:

• Another study interfering with current study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Patients with reconstructed flap monitored by tissue CO2; Patients scheduled for reconstructive flap surgery are monitored postoperatively with IscAlert biosensor measuring local tissue CO2 and temperature in the reconstructed flap	Device: IscAlert; Insertion of a CO2- and temperature sensor(s) in the reconstructed flap.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tissue CO2-level	Tissue CO2-level (kPa) during insertion period	10 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Bleeding	Amount of blood from insertion site (ml)	10 days
Infection	Infection from insertion site at the discretion of the investigator (yes or no)	30 days
Length of stay at hospital	Number of days from end of initial operation to primary hospital discharge + Number of days from transfer from primary hospital to discharge from secondary hospital.	30 days
Time to reduced blood flow in reconstructed flap	Number of days and hours from primary surgery end to obstructed blood flow is diagnosed	30 days
Number of re-operations	Number of reoperations caused by replant necrosis/ischemia in the reconstructed flap	30 days

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of pack-years	Smoking habit; number of pack-years by participants	30 days
Warm ischemia time	Intraoperative ischemia time of the flap (minutes)	12 hours
Intravenous fluid	Intravenous fluid given during surgery (ml)	12 hours
Vasoactive drugs	Vasoactive drugs given during surgery (microgram)	12 hours
Arterial CO2 level	Arterial blood gass analysis of CO2 during hospital stay (kPa)	10 days
Arterial PH level	Arterial blood gass analysis of PH during hospital stay (kPa)	10 days
Arterial lactate level	Arterial blood gass analysis of lactate during hospital stay (kPa)	10 days
Arterial HCO3 level	Arterial blood gass analysis of HCO3 during hospital stay (kPa)	10 days
End-tidal level of CO2	End-tidal level of CO2 during hospital stay (kPa)	10 days
IscAlert functionality	Number of hours with a well-functioning sensor (giving CO2- and temperature data)	10 days
Physical examination of the reconstructed flap - capillary filling	Time of capillary filling (seconds)	10 days
Physical examination of the reconstructed flap - color	Color of reimplanted extremity (Red or Pale)	10 days
Physical examination of the reconstructed flap - SpO2	SpO2 of reimplanted extremity (%)	10 days
Physical examination of the reconstructed flap - temperature	Temperature of reimplanted extremity (degrees Celsius)	10 days
SpO2	SpO2 measured at a finger (%)	10 days
Examination of the reconstructed flap - Doppler	Doppler flowmeter monitoring flow velocity in vascular flap bed (mL/min)	10 days

Collaborators and Investigators

• Sponsor: Oslo University Hospital
• Collaborators: Sensocure AS
• Investigators: Principal Investigator: Magne Røkkum, MD, Ph.D, Oslo University Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 13, 2023
• Primary Completion (Actual): May 30, 2025
• Study Completion (Estimated): October 20, 2027

Study Registration Dates

• First Submitted: August 2, 2022
• First Submitted That Met QC Criteria: August 2, 2022
• First Posted (Actual): August 4, 2022

Study Record Updates

• Last Update Posted (Actual): May 1, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Surgery; Ischemia; Carbon dioxide; Biosensor; Flap; Reconstructive
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Ischemia
• Other Study ID Numbers: DIMENSION

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: No plan to share IPD to other researchers

Drug and device information, study documents

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