Early Discovery of Ischemia After Replantation Surgery of the Extremities

Investigators will test if changes in CO2 is detected postoperatively in ischemic tissue in a replanted extremity of a traumatically amputated upper or lower extremity. 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 replanted extremity. Local tissue CO2 and temperature will be monitored continuously postoperatively for the next 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 replanted extremity and if restricted blood flow is diagnosed, a reoperation will be performed. After reoperation new sensors will be implanted for another ten days if applicable. Sixty 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). 500 devices is planned to be used in this clinical study.

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 extremity replant surgery. Sixty patients will be enrolled to undergo the procedures using a total of 400 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 catheters 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 replanted limb to be operated at the end of surgery or immediate postoperatively. 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 anesthesia (general or regional). 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 replanted extremity and if restricted blood flow is diagnosed or suspected, a reoperation will be performed.

Sixty 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). Approximately 500 devices in 80 injured extremities is planned to be used in this clinical study.

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

Our hypotheses are:

1. The IscAlert™ device will be able to detect the presence of ischemia in the extremity replant 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 replantation survival rates, and less revision surgery caused by replantation thrombosis.
3. No clinically significant bleeding or infection will occur using IscAlert™ in this clinical study.

Eligibility Criteria:
Inclusion Criteria:

* Patients must be in need of extremity replantation surgery
* Subject must be ≥ 18 years
* Able to give written signed informed consent

Exclusion Criteria:

* None