Cerebral Oximetry and Neurological Outcomes in Aortic Arch Surgery Patients
Condition: Postoperative Cognitive Dysfunction
MeSH terms: Postoperative Cognitive Complications; Cognitive Dysfunction
Study type: Interventional
Phase: Phase 3

Summary: 
      The investigators hypothesize that early intervention to optimize regional cerebral
      oxygenation detected by cerebral oximetry monitoring during deep hypothermic circulatory
      arrest (DHCA) for patients undergoing aortic surgery will decrease the incidence of transient
      and permanent neurological dysfunction and improve neurocognitive impairment.
    

Detailed description: 
      Permanent or transient neurologic dysfunction is a frequent complication in patients
      undergoing aortic arch surgery.

      Two basic methods of brain protection are currently used concomitantly with these complex
      surgical procedures: deep hypothermic circulatory arrest (DHCA) with or without retrograde
      cerebral perfusion (RCP)and selective antegrade hypothermic cerebral perfusion. Hypothermic
      circulatory arrest provides an optimal bloodless operative field, but the incidence of
      neurological dysfunction increases when the duration of DHCA exceeds 45-50 minutes. Antegrade
      cerebral perfusion is accomplished by means of direct differential cannulation of the common
      carotid and right subclavian arteries. Because this technique of brain protection requires a
      separate perfusion circuit, vigilant monitoring of perfusion pressure and flow rate is of
      utmost importance. Multiple studies have demonstrated that antegrade selective cerebral
      perfusion is a well established technique used for cerebral protection during aortic surgery
      requiring longer periods of DHCA with favorable results in hospital mortality and neurologic
      outcome. The permanent neurological dysfunction was noted to be 3.8% and the transient
      neurologic dysfunction to be 7.1% for patients that received antegrade selective cerebral
      perfusion.

      Similarly, neurocognitive studies of DHCA with antegrade cerebral perfusion for patients
      undergoing aortic arch operations demonstrated 9 % transient neurocognitive impairment for 2
      days postoperatively that lasted up to 3 weeks thereafter. Consistent with current surgical
      practice, the University of Michigan uses antegrade selective cerebral perfusion for all
      patients undergoing aortic arch surgery requiring DHCA with or without RCP.

      A number of monitoring modalities have been used for detecting cerebral malperfusion during
      aortic surgery or carotid surgery, including transcranial Doppler ultrasound and near
      infrared spectroscopy (NIRS).

      The impact of these monitoring modalities on clinical (neurologic) outcome has not been
      clearly established. Currently, NIRS has gained considerable attention and acceptance as a
      non-invasive monitor of cerebral oxygenation. One study showed that a sustained drop in the
      regional oxygen saturation (rSO2) below 55% for over 5 minutes using cerebral oximetry is
      closely related to the occurrence of neurological events following aortic surgery. Another
      study strongly supported that rSO2 should not drop > 20% from baseline to prevent neurologic
      compromise. In a cohort of elective coronary artery bypass graph (CABG) patients,
      intervention for cerebral desaturations did show significantly less major organ morbidity or
      mortality (death, ventilation > 48 h, stroke, myocardial infarction, return for
      re-exploration. Whether NIRS can be used as a monitor to provide rapid detection and
      prevention of cerebral ischemia by early intervention that may improve neurological outcome
      in patients undergoing aortic surgery requiring DHCA with or without RCP is currently
      unknown.
    

Intervention name(s): INVOS Somanetics Cerebral Oximeter; INVOS Somanetics Cerebral Oximeter
Intervention type(s): Device; Device
Intervention description(s): Sequence of Interventions To Increase Cerebral Oxygen Saturation
Check head and cannula position
Increase mean arterial pressure
Increase pump flow
Increase systemic oxygenation
Increase PaCO2 > 45
Increase anesthetic depth by increasing volatile anesthetic or by administering propofol boluses
Consider PRBC transfusion for Hct < 21%; INVOS Cerebral Oximetry blinded monitoring with no deviation in surgical procedures or standard of care in anesthesia.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Supportive Care
Keywords: Aortic Surgeries; Deep Hypothermic Circulatory Arrest