Continuous Compartment Pressure Monitoring for Compartment Syndrome in VA-ECMO Patients

Acute compartment syndrome (ACS) is a surgical emergency that can develop in patients on extracorporeal membrane oxygenation (ECMO). ACS is a type of limb ischemia, which means that the limb, such as the arm or leg, loses blood flow. Patients on ECMO can develop this condition for many reasons, but most commonly from the ECMO procedure itself. This most commonly involves the leg. Key symptoms of ACS include severe pain, loss of pulses, loss of feeling, and inability to move the limb. However, because patients on ECMO are often sedated, ACS is difficult to diagnose as patients can not report symptoms. As a result, the only available tool for diagnosing ACS may be measurement of pressures in the limb. This is normally done with a needle-device, which is inserted into the leg for a single measurement. However, a recently developed device, called the MY01 Continuous Compartment Pressure Monitor, allows for continuous pressure readings instead of a single measurement. Multiple measurements may allow for much greater accuracy in diagnosing ACS, which may result in faster time to surgery and potentially save more limbs than single measurements. This device may also be less invasive than an older method of continuous pressure measuring, which uses a needle and tubing that is 14-gauge in size. Therefore, this study aims to compare 3 different types of methods for diagnosing ACS in patients on ECMO, which are 1) Standard of Care, 2) Standard of Care and MY01, and 3)Standard of Care and 14-gauge slit catheter.

Acute compartment syndrome (ACS) is a surgical emergency that threatens limb viability and can develop in patients on extracorporeal membrane oxygenation (ECMO). ACS typically develops as a complication secondary to peripheral arterial cannulation and is more common in patients on peripheral veno-arterial (VA) ECMO. The pathophysiologic mechanism of ACS implicates a dramatic increase in compartmental pressures due to the non-compliance of the surrounding osteofascial structures. Without sufficient time for compensatory angiogenesis, the marked fluid extravasation and inflammation within the rigid compartment persists. This increase in pressure leads to compression of neurovascular structures, causing or further perpetuating any pre-existing limb ischemia. The underlying cause of the increased compartmental pressures may be due to a variety of causes in these ECMO patients without a history of trauma, such as ischemia and rhabdomyolysis due to direct disruption of arterial flow (i.e. arterial thromboembolism), obstruction of venous flow (i.e. deep vein thrombosis), direct hemorrhage into the compartment from coagulopathy, or reperfusion injury due to calcium overload and microvascular dysfunction. The treatment of ACS is timely (less than 6 hours from diagnosis) fasciotomy, which is limb-saving.

In awake patients, ACS is a clinical diagnosis relying on medical history, visual examination, palpation of pulses, and symptoms of pallor, paresthesia, out-of-proportion pain with passive stretch, and paresis. Though more technically demanding perhaps, duplex/doppler ultrasound may also be employed as an imaging technique to visualize blood flow and characterize the extent of any obstruction underlying the ischemia. Since the mainstay of diagnosis remains to be the subjective pain of the patient, the diagnosis of ACS in ECMO patients is challenged by the fact that patients on ECMO are typically intubated and receiving sedative medications. Thus, compartment pressure measurements \>30 mmHg may be the only available diagnostic finding in addition to clinical suspicion based on history and tense muscular compartments for diagnosing ACS.

Traditionally, the standard of care for measuring intracompartmental pressure has been using a needle compartment pressure measuring device (Ex. Stryker needle). Some institutions also use a continuous compartment pressure measuring device in the form of a 14-gauge slit catheter attached to a pressure transducer. The main drawback with utilizing the needle compartment measuring device is that it only provides a single time point recording and is difficult to employ for repetitive use. While using the 14-gauge catheter and transducer offers continuous monitoring, this method creates an additional line to manage for patients on ECMO and runs the risk of failing due to clot formation, especially in patients without anticoagulative measures. In summary, diagnosis of ACS in ECMO patients is challenging, and clinicians currently lack a method for accurate, reliable, and continuous measurement of intracompartmental pressure that is well-tolerated.

Employing digital micro sensing technology, the MY01 Continuous Compartmental Pressure Monitor (NXTSens Inc., Montreal, Canada) is a high-precision, implantable device that can continuously measure intracompartmental pressure. Having shown over 600% improved accuracy when compared to standard compartment pressure measuring devices, this advanced sensory microsystem can provide pressures with an accuracy of ±0.008 mmHg, which are then relayed to a cloud storage database as well as the MY01 mobile application for easy accessibility. With such reliable and real-time continuous pressure monitoring, MY01 may be the optimal diagnostic tool for ACS in patients on ECMO and lead to more prompt, limb-saving surgical fasciotomies.

Therefore, the investigators hypothesize that the MY01 device in conjunction with current standard of care will help identify which patients on VA-ECMO have ACS more precisely than current standard of care alone, which includes physical exam findings and single timepoint needle compartment measurement. Additionally, the investigators hypothesize that the MY01 device will be less invasive and easier to use than previously described methods of continuous compartment pressure monitoring utilizing a 14-gauge slit catheter.

Eligibility Criteria:
Inclusion Criteria:

* Adults ≥18 years of age
* Peripheral Venoarterial-Extracorporeal membrane oxygenation
* Sedated

Exclusion Criteria:

* Any limb ischemia diagnosis prior to ECMO cannulation
* Any severe extremity trauma that precludes insertion of device
* Very poor prognosis (survival \>72 hours is unlikely), which also includes severe coagulopathy. Severely coagulopathic patients are at risk for severe hemorrhage and thus may not survive fasciotomy.