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[George Miklos]

We are thinking of introducing this monitor for cardiac surgery soon. Does anyone have any experience with it? Does it have a practical value (rather than just a theoretical one)?

Here is the blurb from the company (and, no, I am not associated with them  )

The INVOS Cerebral Oximeter

The INVOS® Cerebral Oximeter is the first and only patient monitoring system commercially available in the U.S. that noninvasively and continuously monitors changes in the regional oxygen saturation of the blood in the brain.

The INVOS Cerebral Oximeter system consists of disposable, single-patient use SomaSensors, an INVOS monitor display and associated accessories.

The INVOS Cerebral Oximeter system monitors changes in regional saturation of oxygen, or rSO2, within a sample of blood in the cerebral cortex. Changes in INVOS (In Vivo Optical Spectroscopy) values monitor the critical balance between oxygen delivery and cerebral consumption.

The INVOS Cerebral Oximeter measurement is made by noninvasively transmitting and detecting harmless, low intensity and near infrared light through SomaSensors that are placed on both sides of a patient's forehead.

Use of the patient monitoring system allows medical professionals to monitor changes in cortical blood oxygen saturation and take corrective action. Recent research and clinical experience indicates that such action can prevent or reduce neurological injuries associated with surgery and other critical cares situations, and therefore, reduce the cost of care.

The INVOS Cerebral Oximeter system is now available for adult and pediatric monitoring in the US and in many international markets.

[gasman]

A quick Google search found this:

Objectives:
The timing of bifrontal decompressive craniectomy (BDC) in patients with intractable intracranial hypertension (IH) is crucial, and the decision to do surgery is based primarily on invasive neuromonitoring. In this report the authors show the efficacy of a non-invasive, near infrared transcranial cerebral oximeter (TCCO) in the management of a patient with post-traumatic IH.

Clinical Presentation:
A 14-year-old male patient who had severe head injury following road traffic accident (RTA). His Glasgow Come Score (GCS) was 6/15. Brain computerized tomography (CT) scan showed multiple brain contusions and diffuse brain edema. He developed a state of IH that did not respond to standard medical treatment. We have used TCCO for neuromonitoring, its readings showed marked difference between the two cerebral hemispheres and this correlated well with the clinical and radiological findings.

Intervention:
Because of the decreasing trend of cerebral oxygen saturation and pupillary changes (anisocoria) BDC was performed. The timing of surgery was appropriate as no brain infarction occurred. Following surgery, TCCO readings were normal and the patient recovery was dramatic and relatively quick.

Conclusion:
TCCO may be an efficient Neuromonitoring tool in determining the time for surgical interference in patients with IH following RTA.

Citation:
Sherif El-Watidy, Abdelazeem El-Dawlatly, Zain A. Jamjoom, Essam El-Gamal: Use of Transcranial Cerebral Oximeter as Indicator for Bifrontal Decompressive Craniectomy. The Internet Journal of Anesthesiology. 2004. Volume 8 Number 2.

But also This:

Crit Care Med. 1997 Jul;25(7):1252-4.

Failure of the INVOS 3100 cerebral oximeter to detect complete absence of cerebral blood flow.

Gomersall CD, Joynt GM, Gin T, Freebairn RC, Stewart IE.

Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT.

[gasman]

And more:

The Utility of Cerebral Oximetry in Critically Ill Patients
Susan Marlow, Ken Parsons, Violet Miller and Brian J O'Neil
Saint John Hospital: Detroit, MI

ABSTRACT

Objective:
Jugular bulb oxygen saturation has been correlated to the adequacy of resuscitation and neurologic outcomes in critically ill patients. Regional cerebral oximetry (rSO2) provides a continuous, non-invasive method to monitor cerebral oxygen saturation in the frontal lobes, which is highly correlated with jugular bulb oxygenation. Our aim is to study the utility of rSO2 in the resuscitation of critically ill patients in the emergency department (ED).

Hypothesis:
Cerebral oximetry predicts the adequacy of resuscitation and neurologic outcomes.

Methods:
A prospective observational study was performed on a convenience sample of critically ill patients with altered mental status at a community hospital ED. The INVOS cerebral oximeter was used to detect rSO2. Cerebral oximetry, vital signs, acid—base status, lactates interventions, creatine kinase—BB (CK-BB), and neurologic status at hospital discharge were recorded. Outcome measures were neurologic outcome, defined by the Glasgow Outcome Scale, and adequacy of resuscitation (AOR), defined by base deficit and lactate levels. Data were analyzed utilizing descriptive statistics and Pearson correlation.

Results:
Twelve subjects were enrolled. Five patients either maintained or were quickly resuscitated to rSO2 levels between 50% and 80% and all displayed both adequate resuscitation and returned to normal activity. Five patients had rSO2 outside the above range, 4 below (all with inadequate resuscitation), and 1 above, (large frontal bleed), all 5 of whom died. Two patients had rSO2 within normal ranges; both had intracranial bleeding in the posterior circulation and poor neurologic outcomes. The rSO2 had positive predictive values (PPVs) of 100% and 57% and negative predictive values (NPVs) of 40% and 100% for neurologic outcome and AOR, respectively.

Conclusion:
In critically ill patients, cerebral oximetry has excellent positive and negative predictive values for neurologic outcome and adequacy of resuscitation, respectively. This study is limited by the small sample size.

And this link is also interesting:

Sudden Severe Hypotension During Induction Of Anesthesia For Carotid Endarterctomy (CEA):
The Utility Of NIRS. A Case Report.

[Bucky]

One locum tenens site where I worked a week uses this monitor during carotid endarterectomies.  They swear by it.  Looks efficacious from what I could see of its use.

[Matthew Parsons]

How much does it cost (onc-off cost and ongoing disposables)?

As with a lot of new technologies, it often comes down to cost-benefit ratios.

[combest]

Very recently introduced into my practice.  I am still learning a bit more about these;  my pet peeve so far is that the perfusionist tells me that the reading can be influenced by patient's skin tone, but does not put the sensor on until after general anesthesia has been induced.  So is that lower-that-expected reading because I am not controlling hemodynamics to provide adequate perfusion or is the darker skin tone altering the readings?  Seems to me that he should put the sensor on before significant sedation is given in order to see what the baseline reading is, esp on my patients with darker skin tones.  Need to do this next time.