Clinical Reports

Adult Cardiac Surgery Clinical Reports and Abstracts

This section is intended to provide you clinical reports for the INVOS Cerebral Oximeter.
We will update this section with abstracts and other Clinical Reports, as they become available.

A link to the document is provided when available. These links may take you to
another site such as PubMed.

Adult Cardiac Surgery

Edmonds HL Jr, Ganzel BL, Austin EH 3rd. Cerebral oximetry for cardiac and vascular
surgery. Semin Cardiothorac Vasc Anesth. 2004;8:147-66. [Abstract] [PubMed]

Goldman S, Sutter Francis, Ferdinand F, Trace C. Optimizing intraoperative cerebral oxygen
delivery using noninvasive cerebral oximetry decreases the incidence of stroke for cardiac
surgical patients. Presented during the Cardiothoracic Techniques and Technologies Annual
Meeting, March 10-13, 2004, Miami Beach, Florida. [Abstract]

Murkin JM, Adams S, Schaefer B, Irwin B, Fox S. Monitoring cerebral oxygen saturation
significantly decreases stroke rate in CABG patients: A randomized blinded study. Presented
at the Outcomes 2004:The Key West Meeting, Florida, May 19-24, 2004. [Abstract]

Papadimos TJ, Marco AP. Cerebral oximetry and an unanticipated circulatory arrest.
Anaesthesia 2004;59:309-310. [Case Report]

Bar-Yosef S, Sanders EG, Grocott HP. Asymmetric cerebral near-infrared oximetric
measurements during cardiac surgery. J Cardiothorac Vasc Anesth 2003;6:773-774.
[Case Report]

Fukada J, Morishita K, Kawaharada, Yamauchi A, Hasegawa T, Satsu T, Abe T. Isolated
cerebral perfusion for intraoperative cerebral malperfusion in Type A aortic dissection.
Ann Thorac Surg 2003;75:266-8. [Case Report] [PubMed]

Iglesias I, Murkin JM, Bainbridge D, Adams S. Monitoring cerebral oxygen saturation
significantly decreases postoperative length of stay: A prospective randomized study.
Presented at Outcomes 2003: The Key West Meeting, Florida. Heart Surgery Forum
2003;6:204 [Abstract]

Janelle GM, Clark TD, Gravenstein N, Staples ED, Urdaneta F. Case report:Cerebral oxygen
desaturation during lung transplantation involving cardiopulmonary bypass: Evidence
for a new approach for managing patients with chronic hypercarbia. Anesth Analg
2003;96,SCA86. [Case Report]

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Semin Cardiothorac Vasc Anesth. 2004 Jun;8(2):147-66.

Cerebral oximetry for cardiac and vascular surgery.

Edmonds HL Jr, Ganzel BL, Austin EH 3rd.

Department of Anesthesiology and Perioperative Medicine, Division of
Cardiothoracic Surgery, University of Louisville School of Medicine, Louisville,
Kentucky.

The technology of transcranial near-infrared spectroscopy (NIRS) for the
measurement of cerebral oxygen balance was introduced 25 years ago. Until very
recently, there has been only occasional interest in its use during surgical
monitoring. Now, however, substantial technologic advances and numerous
clinical studies have, at least partly, succeeded in overcoming long-standing and
widespread misunderstanding and skepticism regarding its value. Our goals are to
clarify common misconceptions about near-infrared spectroscopy and acquaint
the reader with the substantial literature that now supports cerebral oximetric
monitoring in cardiac and major vascular surgery.

PMID: 15248000 [PubMed - in process]

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Presented at the Cardiothoracic Techniques and Technologies Annual Meeting,
March 10-13, 2004, Miami Beach, Florida.

Optimizing Intraoperative Cerebral Oxygen Delivery Using Noninvasive
Cerebral Oximetry Decreases the Incidence of Stroke for Cardiac Surgical
Patients

Scott Goldman, M.D., Francis Sutter, D.O., Francis Ferdinand, M.D. and
Candace Trace

Division of Thoracic and Cardiovascular Surgery, Main Line Health Heart Center -
The Lankenau Hospital and Institute for Medical Research, Wynnewood, PA USA.

Background: A recent study demonstrated that almost 75% of strokes after coronary
artery revascularization surgery occur in patients classified preoperatively as low to
medium risk. Thus, despite the use of risk classification, the majority of strokes can
occur when not expected. We hypothesized that optimization of cerebral oxygen
delivery variables using noninvasive cerebral oximetry could reduce the incidence of
stroke. Methods: Cerebral oximetry was used by all surgeons to monitor cerebral
oxygen saturation in all cardiac surgery patients beginning January 1, 2002 until
June 30, 2003 (18 months, treatment group). Cerebral oxygen delivery was optimized
during surgery by modifying oxygen delivery and consumption variables to maintain
oximetry values at or near the patient's pre-induction baseline. Stroke was defined
according to STS guidelines. The incidence of stroke in the treatment group was
compared to that for patients undergoing cardiac surgery between July 1, 2000 and
December 31, 2001 (18 months, control group) before cerebral oximetry was
incorporated. Results: Age and gender distribution were similar in the two groups. The
table provides stroke data for all cardiac surgeries as well as CABG only surgeries.
The total N and the number and percentage of strokes in each group are shown and
percentages are compared to the expected incidence derived from STS statistics.
Conclusions: The treatment group undergoing all cardiac surgeries with optimized
cerebral oxygen delivery utilizing cerebral oximetry monitoring demonstrated a
significant decrease in the incidence of stroke. The group with CABG only also
demonstrated a lower stroke rate but larger numbers are needed to show significance.

Control Group

Treatment Group

July 1, 2000 to Dec. 31, 2001

Jan. 1, 2002 to June 30, 2003

Category
N

Strokes (%)

STS %

N

Strokes (%)

STS %

All Cases
1245

25 (2.01%)

NA

1034

10 (0.97%)

NA

CABG only
832

12 (1.44%)

1.60%

664

5 (0.75%)

1.40%

* P<0.045 compared to control patients

Reference: Likosky DS et al., Ann Thor Surg 2003;76:428-35.

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Presented at the Outcomes 2004:The Key West Meeting, Florida, May 19-24, 2004.

Monitoring Cerebral Oxygen Saturation Significantly Decreases Stroke
Rate in CABG Patients: A Randomized Blinded Study.

Murkin JM, Adams S, Schaefer B, Irwin B, Fox S.

Department of Anesthesia and Perioperative Medicine, University of Western
Ontario, London, Ontario, Canada.

INTRODUCTION: Cerebral oxygen desaturation has been associated with
prolonged intensive care unit and total hospital lengths of stay.
This study prospectively evaluated the use of near-infrared spectroscopy
(NIRS) to monitor the impact of interventions to improve regional cerebral
oxygen saturation (rSO2) on postoperative outcome after coronary artery
bypass surgery. METHODS: After ethics board approval and written
informed consent, patients were age stratified and randomly assigned to
Control group (Group C) or Intervention group (Group I). Both groups had
bilateral frontal electrodes to measure rSO2 during the operation, in
Group I patients the monitor was visible and efforts to keep the rSO2 on
levels = 75% of preinduction value by sequentially increasing perfusion
pressure, pump flow, PaCO2 (if < 35 mmHg), FiO2, decrease temperature
(if > 370C), increase PaCO2 > 45 mmHg increase Hct (if < 20%); in
Group C patients the monitor was covered and the patient was managed
routinely. All patients were assessed by an independent observer for
adverse clinical outcomes including respiratory failure, CT or MRI confirmed
stroke, renal failure, Ml, or perioperative death, Statistical anaIysis was
performed using the Chi-square or Fishers exact test with p< 0.05 required
for significance. RESULTS: 186 patients were included in the study
(93 Group C, 93 Group I). 4 clinical stokes were detected in Group C vs 1
clinical stroke in Group I (p < 0.01). There were significantly fewer adverse
clinical outcomes in monitored vs control groups (p = 0.009).

CONCLUSION: Monitoring and maintaining rSO2 above 75% of pre-induction values
was associated with a significant decrease in perioperative stroke rate and overall
number of adverse clinical outcomes.

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Anaesthesia, 2004, 59, pages 309-310 Correspondence

Cerebral Oximetry and an Unanticipated Circulatory Arrest

T. J. Papadimos, A. P. Marco

Medical College of Ohio, Toledo, Ohio 43614, USA

Cerebral oximetry is used at our institution on patients undergoing coronary artery bypass
grafting (CABG). This device (INVOS, Somanetics) monitors changes in the regional
oxygen saturation (rSO2) in the cerebral cortex. Sequential determinations are made of
the average regional haemoglobin oxygen saturation (trended rSO2 index in percent)
allowing recognition of dysoxia [1-3]. (Dysoxia is a more specific term (than hypoxia)
that signifies hypoxia severe enough to cause functional abnormalities). The use of such a
monitoring system has been reported to reduce neurological injuries, renal failure, and
hospital length of stay in cardiac surgery patients [4,5]. A 20% rSO2 decrease from
baseline during the case is within acceptable limits with a minimal acceptable reading of
45% [6,7]. We report the correction of a potentially critical event (dysoxia) detected with
use of this device that otherwise would have been unrecognised. A 78 year-old women
with aortic stenosis, coronary artery disease and unstable angina, congestive heart failure,
and a myocardial infarction three months previously was scheduled for aortic valve
replacement and three vessel coronary artery bypass grafting. Her past medical history
also included hypertension, noninsulin dependent diabetes mellitus,
hypercholesterolaemia, obesity, renal insufficiency and seizures. Preoperative
transthoracic echocardiography indicated mild left ventricular hypertrophy, moderate left
ventricular diastolic dysfunction, severe aortic stenosis (valve area 0.6 cm2), and a left
ventricular ejection fraction of 35%. The maximum blood velocity in the aortic root was
4.9 ms)1 and the maximum pressure gradient across the aortic valve was 94 mmHg with
a mean gradient to 59 mmHg. Carotid duplex scans revealed bilateral, scattered,
heterogenous plaques. After induction of anaesthesia, the cerebral oximeter indicated
initial rSO2 readings of left (L) 48% and right (R) 66%. Anaesthesia was maintained with
3% desflurane in oxygen with fentanyl. Immediatley prior to aortic crossclamping the L
rSO2 was 50% and the R rSO2 was 95%. Arterial blood gas analysis at this time revealed
pH 7.43, PaCO2 4.9 kPa, PaO2 56 kPa, and HCO3 24 mmol l)1. At the initiation of
cardiopulmonary bypass (CPB) the L rSO2 decreased to 28% while the right side showed
no change, indicating possible impairment of perfusion in the distribution of the left
carotid artery. The peripheral arterial blood saturation at this time was 100% on 100%
inspired oxygen and a mean arterial pressure of 63 mmHg. To reduce the potential for
a poor neurological outcome the following interventions were performed: (1) the head
was adjusted to the right in case decreased flow through the left carotid artery was due to
positioning, (2) the mean arterial pressure was increased using phenylephrine, (3)
cerebral blood flow was increased by decreasing the sweep speed on the oxygen . carbon
dioxide exchanger resulting in an increase in the PaCO2 from 4.4 kPa to 6.9 kPa, and (4)
the blood oxygen carrying capacity was increased by giving two units of packed red
blood cells (the haemoglobin was < 9 g.dl)1). These maneuvers increased the L
rSO2)52%. Three hours and 28 min after aortic cross-clamping it was determined that a
circulatory arrest was necessary to complete an unexpected aortic root replacement. The
circulatory arrest lasted 40 min and was followed by resumption of CPB (total bypass
time was 311 min). The patient was separated from CPB without incident, and transferred
to the intensive care unit. She was extubated two days later, at which time she was
cognitively and neurologically intact. Until the advent of cerebral oximetry there was no
method for assessing cerebral oxygenation. Cerebral oximetry allowed us to identify
cerebral dysoxia and intervene. This may have been pivotal in our patient, especially in
view of the necessity of a circulatory arrest and a prolonged CPB time. An rSO2 of 50%
would represent a PaO2 of 3.2 kPa and an rSO2 of 28% corresponds to a PaO2 of
2.5 kPa. While the decrease in PaO2 may seem small it may have made an important
impact on oxygen delivery to the brain because the patient was on the steep part of the
oxyhaemoglobin dissociation curve (especially if her brain was ischaemic or in a state of
compensated hypoperfusion). We have associated cerebral blood flow with rSO2, but it
may actually be more accurate to state that cerebral oximetry measures cerebral
haemoglobin oxygen saturation and the balance between supply and demand [10]. Using
absolute values of INVOS devices has been criticised, but monitoring the dynamic
changes has value [8]; such value has been demonstrated during cerebral hypoxia in a
rapidly expanding neck haematoma necessitating immediate surgical intervention [9].
Further work indicates that neurophysiologic monitoring in cardiac surgery done in a
multimodal fashion with cerebral oximetry used in conjunction with
electroencephalography and transcranial Doppler ultrasonography is safe, clinically
beneficial and cost-effective [11]. However, of all the invasive and noninvasive
technologies currently available cerebral oximetry may have the largest potential for
further improvement [12]. Cerebral oximetry provides a realtime objective measurement
of cerebral oxygenation that can provide the cardiac anaesthetist with an early warning
regarding dysoxia thus allowing timely interventions that may reduce complications and
promote cost savings to hospitals and insurers.

References
1 Jobsis FE. Noninvasive infrared monitoring of cerebral and myocardial oxygen
sufficiency and circulatory parameters. Science 1977; 198: 1264-7.
2 McCormick PW, Stewart M, Goetting MG, Dujovy M, Lewis G, Ausman JI.
Noninvasive cerebral optic spectroscopy for monitoring cerebral oxygen delivery and
hemodynamics. Critical Care Medicine 1999; 19: 89-97.

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Heart Surgery Forum 2003;6:204

Monitoring Cerebral Oxygen Saturation Significantly Decreases Postoperative
Length of Stay: A Prospective Randomized Blinded Study

Iglesias I, Murkin JM, Bainbridge D, Adams S

Department of Anesthesia and Perioperative Medicine, University of Western Ontario,
London, Ontario, Canada.

INTRODUCTION: Cerebral oxygen desaturation has been associated with prolonged
intensive care unit and total hospital lengths of stay. This study evaluated the use of
near-infrared spectroscopy (NIRS) to monitor the impact of interventions to improve
regional cerebral oxygen saturation (rSO2) on postoperative outcome after coronary
artery bypass surgery.
METHODS: After ethics board approval and written informed consent, patients were
age stratified and randomly assigned to Control group (Group C) or Intervention
group (Group I). Both groups had bilateral frontal electrodes to measure rSO2 during
the operation, in Group I patients the monitor was visible and efforts to keep the rSO2
on levels > or = to 75% of preinduction value by sequentially increasing perfusion
pressure, pump flow, PaCO2 (if < 35 mmHg), FiO2, decrease temperature (if > 37°C),
increase PaCO2 > 45 mmHg, increase Hct (if <20%); in Group C patients the monitor
was covered and the patient was managed routinely. Statistical analysis was performed
using the Wilcoxon Rank Sums (WRS) for asymmetrical distributions with p<0.05
required for significance.
RESULTS: 98 patients were included in the study (54 Group C, 44 Group I), neurological
complications were detected in 6 patients from the Group C [3 strokes] and in 5 patients
in Group I [no strokes], and were not statistically significant. When comparing Length of
Stay-LOS-between the groups there was a significantly shorter LOS in the Group I with
odds ratio in the control group for a 10 or more days length of stay in hospital of 7.58 (p=0.03)

CONCLUSION: Monitoring and maintaining rSO2 above 75% of pre-induction
values was associated with a decreased length of stay in patients undergoing
uncomplicated CAB surgery.

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