The Association of High Jugular Bulb Venous Oxygen Saturation with Cognitive Decline After Hypothermic Cardiopulmonary Bypass

Neuromonitoring and Neurocognitive Outcomes in Cardiac Surgery: A Narrative Review

Neurocognitive dysfunction after cardiac surgery can present with diverse clinical phenotypes, which include postoperative delirium, postoperative cognitive dysfunction, and stroke, and it presents a significant healthcare burden for both patients and providers. Neurologic monitoring during cardiac surgery includes several modalities assessing cerebral perfusion and oxygenation (near-infrared spectroscopy, transcranial Doppler and jugular venous bulb saturation monitoring) and those that measure cerebral function (processed and unprocessed electroencephalogram), reflecting an absence of a single, definitive neuromonitor. This narrative review briefly describes the technologic basis of these neuromonitoring modalities, before exploring their use in clinical practice, both as tools to predict neurocognitive dysfunction, and with a bundle of interventions designed to optimize cerebral oxygen supply, with the aim of reducing postoperative delirium and cognitive dysfunction following cardiac surgery.

Effects of obstructive sleep apnoea severity on neurocognitive and brain white matter alterations in children according to sex: a tract-based spatial statistics study

OBJECTIVES

To investigate alterations in neurocognitive, attention, paediatric sleep questionnaire (PSQ) scores and whole brain white matter (WM) integrity between children with mild and severe obstructive sleep apnoea (OSA) according to sex and whether these changes are associated with OSA severity.

METHODS

Fifty-seven children (36 males and 21 females) diagnosed with OSA were recruited for this study. Children of both sexes were divided into mild (male-MG, female-MG) and severe (male-SG, female-SG) groups according to OSA severity. Polysomnography (PSG), neurocognitive, attention and PSQ tests were compared between groups by one-way samples analysis of variance (ANOVA) F test. Diffusion tensor imaging (DTI) was scanned using a 3T GE MRI scanner and analysed by Tract-based Spatial Statistics (TBSS). Spearman correlation was calculated between DTI Eigenvalues and clinical characteristics.

RESULTS

Compared to mild OSA patients, severe OSA patients presented greater severity of obstructive apnoea hypopnea index (OAHI), neurocognition, PSQ and attention tests in both male and female patients. Brain WM integrity in the male-SG, compared to the male-MG, demonstrated significantly reduced fractional anisotropy (FA) values in the right middle frontal gyrus and the right frontal sub-gyral regions and increased axial diffusivity (AD) values in the right inferior frontal gyrus, left parietal angular gyrus and sub-gyral regions, while no differences were found between the female-MG and female-SG. Alterations in male-SG brain regions were observably correlated with severity in male OSA patients.

CONCLUSIONS

The integrity of WM, which regulates autonomic, cognitive, and attention functions, is impaired in male, but not female, children with severe OSA.

Chronic Thromboembolic Pulmonary Hypertension and Pulmonary Thromboendarterectomy

Chronic thromboembolic pulmonary hypertension results from incomplete resolution of a pulmonary embolus or from recurrent pulmonary emboli. Its incidence is underappreciated, and it is currently an undertreated phenomenon. Pulmonary thromboendarterectomy is currently the safest and most effective treatment for this condition. The surgery involves midline sternotomy, profound hypothermic circulatory arrest, and complete endarterectomy of the pulmonary vascular tree. Success depends on effective coordination of multiple medical teams, including pulmonary medicine, anesthesiology, and surgery. This review, based on the past 30 years of experience at University of California San Diego Medical Center, includes information about the clinical history, diagnostic workup, anesthesia, surgical approach, and postoperative care. Outcome data are discussed, as are avenues for future research.

Perioperative hyperglycemia is associated with postoperative neurocognitive disorders after cardiac surgery

OBJECTIVE

Neurocognitive disorders commonly occur following cardiac surgery. However, the underlying etiology of these disorders is not well understood. The current study examined the association between perioperative glucose levels and other risk factors and the onset of neurocognitive disorders in adult patients following coronary artery bypass and/or valvular surgery.

METHODS

Adult patients who underwent their first cardiac surgery at a large tertiary care medical center were identified and those with neurocognitive disorders prior to surgery were excluded. Demographic, perioperative, and postoperative neurocognitive outcome data were extracted from the Society for Thoracic Surgery database, and from electronic medical records, between January 2004 and June 2009. Multiple clinical risk factors and measures associated with insulin resistance, such as hyperglycemia, were assessed. Multivariable Cox competing risk survival models were used to assess hyperglycemia and postoperative neurocognitive disorders at follow up, adjusting for other risk factors and confounding variables.

RESULTS

Of the 855 patients included in the study, 271 (31.7%) had new onset neurocognitive disorders at follow-up. Age, sex, New York Heart Failure (NYHF) Class, length of postoperative intensive care unit stay, perioperative blood product transfusion, and other key factors were identified and assessed as potential risk factors (or confounders) for neurocognitive disorders at follow-up. Bivariate analyses suggested that new onset neurocognitive disorders were associated with NYHF Class, cardiopulmonary bypass, history of diabetes, intraoperative blood product use, and number of diseased coronary vessels, which are commonly-accepted risk factors in cardiac surgery. In addition, higher first glucose level (median =116 mg/dL) and higher peak glucose >169 mg/dL were identified as risk factors. Male sex and nonuse of intra-operative blood products appeared to be protective. Controlling for potential risk factors and confounders, multivariable Cox survival models suggested that increased perioperative first glucose measured in 20 unit increments, was significantly associated with the onset of postoperative neurocognitive disorders at follow-up (hazard ratio [HR] =1.16, P<0.001) and that women had an elevated risk for this outcome (HR =4.18, P=0.01).

CONCLUSION

Our study suggests that perioperative hyperglycemia was associated with new onset of postoperative neurocognitive disorders in adult patients after cardiac surgery, and that men tended to be protected from these outcomes. These findings may suggest a need for the revision of clinical protocols for perioperative insulin therapy to prevent long-term neurocognitive complications.

Determinants of regional cerebral oxygenation in children with sleep-disordered breathing

RATIONALE

An association between neurocognitive deficits and pediatric sleep-disordered breathing has been suggested; however, weak correlations between disease severity and functional outcomes underscore the lack of knowledge regarding factors modulating cognitive morbidity of sleep-disordered breathing.

OBJECTIVES

To identify the parameters affected by sleep-disordered breathing that modulate cerebral oxygenation, an important determinant of cognition. A further objective was to use these parameters with demographic data to develop a predictive statistical model of pediatric cerebral oxygenation.

METHODS

Ninety-two children (14 control subjects, 32 with primary snoring, and 46 with obstructive sleep apnea) underwent polysomnography with continuous monitoring of cerebral oxygenation and blood pressure. Analysis of covariance was used to relate the blood pressure, sleep diagnostic parameters, and demographic characteristics to regional cerebral oxygenation.

MEASUREMENTS AND MAIN RESULTS

To account for anatomic variability, an index of cerebral oxygenation during sleep was derived by referencing the measurement obtained during sleep to that obtained during wakefulness. In a repeated measures model predicting the index of cerebral oxygenation, mean arterial pressure, rapid eye movement (REM) sleep, female sex, age, and oxygen saturation had a positive effect on cerebral oxygenation levels, whereas arousal index and non-REM (NREM) sleep had a negative effect.

CONCLUSIONS

Increasing mean arterial pressure, age, oxygen saturation, and REM sleep augment cerebral oxygenation, while sleep-disordered breathing, male sex, arousal index, and NREM sleep diminish it. The proposed model may explain the sources of variability in cognitive function of children with sleep-disordered breathing.

Chronic AT1-receptor blockade does not alter cerebral oxygen supply/demand ratio during cardiopulmonary bypass in hypertensive patients

BACKGROUND

The angiotensin II receptor type 1 antagonist candesartan has been hypothesized to alter vasopressor requirements and brain-blood flow by changing cerebrovascular autoregulation. Therefore, we assessed the effects of a pre-anaesthetic treatment course with candesartan on cerebral arterial-jugular bulb oxygen content difference, middle cerebral artery blood velocity, and vasopressor requirements in hypertensive patients undergoing elective on-pump coronary artery bypass graft surgery.

METHODS

In a randomized, double-blind, placebo-controlled study, we evaluated the effects of candesartan (8 mg po/d, given for 6-8 days before surgery) in 35 hypertensive patients. The mean arterial pressure was maintained above 60 mmHg by bolus administration of phenylephrine, if required, and dosages were recorded.

RESULTS

Candesartan did not significantly alter oxygen content difference across the cerebral circulation, mean middle cerebral artery blood velocity during cardiopulmonary bypass, or phenylephrine requirements either before (0.0067 microg/kg/min+/-0.0042 vs. 0.0056 microg/kg/min+/-0.0049, P=0.48) or during cardiopulmonary bypass (0.0240 microg/kg/min+/-0.0240 vs. 0.0250 microg/kg/min+/-0.0190, P=0.97) compared with placebo.

CONCLUSION

Thus, a 6-8-day treatment course with candesartan does not alter global cerebral perfusion and oxygen supply/demand ratio during cardiopulmonary bypass, or vasopressor requirements in hypertensive patients undergoing on-pump coronary artery bypass graft surgery, and no deleterious consequences of AT1-receptor blockade were detected.

Clinical evaluation of time-resolved spectroscopy by measuring cerebral hemodynamics during cardiopulmonary bypass surgery

We developed a three-wavelength time-resolved spectroscopy (TRS) system, which allows quantitative measurement of hemodynamics within relatively large living tissue. We clinically evaluated this TRS system by monitoring cerebral circulation during cardiopulmonary bypass surgery. Oxyhemoglobin, deoxyhemoglobin, total hemoglobin and oxygen saturation (SO(2)) were determined by TRS on the left forehead attached with an optode spacing of 4 cm. We also simultaneously monitored jugular venous oxygen saturation (SjvO(2)) and arterial blood hematocrit (Hct) using conventional methods. The validity and usefulness of the TRS system were assessed by comparing parameters obtained with the TRS and conventional methods. Although the changes in SO(2) were lower than those in SjvO(2), SO(2) obtained by TRS paralleled the fluctuations in SjvO(2), and a good correlation between these values was observed. The only exceptions occurred during the perfusion period. Moreover, there was a good correlation between tHb and Hct values (r(2)=0.63). We concluded that time-resolved spectroscopy reflected the conditions of cerebral hemodynamics of patients during surgical operations.

Anesthesia for pulmonary endarterectomy

Anesthetic care for patients undergoing pulmonary endarterectomy represents one of the most challenging tasks in cardiac anesthesia. Chronic thromboembolic pulmonary hypertension with its concomitant right ventricular failure may cause hemodynamic instability during anesthetic induction and the precardiopulmonary bypass (CPB) period, and the associated comorbidities (pulmonary, hepatic) may affect the actions and metabolism of anesthetic drugs. During the CPB period, proper perfusion patterns, cerebral oxygenation, and adequate hypothermia for deep hypothermic circulatory arrest must be achieved. During the post-CPB period the anesthesiologist must be prepared to treat residual pulmonary hypertension, pulmonary edema, pulmonary bleeding, right ventricular failure, and various metabolic and cardiovascular sequelae of hypothermic circulatory arrest. This review highlights the main issues the anesthesiologist faces during pulmonary endarterectomy, as well as suggests approaches to their management.

Is Depth of Anesthesia, as Assessed by the Bispectral Index, Related to Postoperative Cognitive Dysfunction and Recovery?

We randomized 74 patients to either a lower Bispectral Index (BIS) regimen (median BIS, 38.9) or a higher BIS regimen (mean BIS, 50.7) during the surgical procedure. Preoperatively and 4-6 wk after surgery, the patients' cognitive status was assessed with a cognitive test battery consisting of processing speed index, working memory index, and verbal memory index. Processing speed index was 113.7 +/- 1.5 (mean +/- se) in the lower BIS group versus 107.9 +/- 1.4 in the higher BIS group (P = 0.006). No difference was observed in the other two test battery components. Somewhat deeper levels of anesthesia were therefore associated with better cognitive function 4-6 wk postoperatively, particularly with respect to the ability to process information.

A comparison of postoperative cognitive function and pain relief with fentanyl or tramadol patient-controlled analgesia

STUDY OBJECTIVE

The use of different opioids for patient-controlled analgesia (PCA) may affect postoperative cognitive function differently. Patient-controlled analgesia fentanyl has been shown to preserve cognitive function better than morphine. The effect of PCA tramadol on cognitive function is unknown. This study aims to compare postoperative cognitive function and analgesia of PCA fentanyl or tramadol.

DESIGN

Prospective randomized double-blinded study.

SETTING

Metropolitan teaching hospital.

PATIENTS

30 ASA physical status I, II, and III patients undergoing lower abdominal operations.

INTERVENTIONS

Patients received standard general anesthesia for their operations. Postoperatively, patients received either fentanyl (group F, 10 mug bolus, n = 17) or tramadol (group T, 20 mg bolus, n = 13) for PCA. Group F patients also received fentanyl boluses and group T patients received tramadol boluses intraoperatively.

MEASUREMENTS

Cognitive function was measured using Mini-Mental State Examination and Benton Visual Retention Test (BVRT) preoperatively and on days 1 and 2. Pain was measured by numerical rating scale.

RESULTS

No differences were found in postoperative Mini-Mental State Examination or BVRT scores, but significantly fewer (29.4%; 95% confidence interval [CI], 13.3%-53.1%) group F patients were able to complete BVRT compared with group T patients (84.6%; 95% CI, 57.8%-95.7%; 95% CI of difference, 19.4%-74.8%) (P = 0.010) on day 1. In the first 24 hours, group F and group T patients had similar analgesia at rest, but group T patients had better analgesia during cough (mean Numeric Rating Scale, 7.6; 95% CI, 7.0-8.2 vs 6.0; 95% CI, 4.8-7.2, group F vs group T) (P = 0.018; 95% CI of difference, 0.4-2.8). No differences were found in frequency of side effects or patient satisfaction.

CONCLUSIONS

Tramadol or fentanyl PCA has similar cognitive effects on days 1 and 2; however, patients receiving tramadol PCA are more motivated to undergo cognitively demanding tasks and have slightly better analgesia on postoperative day 1.

Jugular bulb desaturation during coronary artery surgery: a comparison of off-pump and on-pump procedures † †Presented in part at the annual Outcomes Meeting at Key West, FL, USA, 2001. ‡ ‡This article is accompanied by the Editorial

BACKGROUND

Conventional coronary artery bypass surgery has been associated with cerebral injury attributed to cardiopulmonary bypass (CPB) and surgical manipulation of the ascending aorta. Off-pump coronary artery surgery avoids these factors and could prevent cerebral injury. However, moving the heart from its natural position affects the circulation and could compromise cerebral oxygenation and perfusion. We set out to compare episodes of poor global cerebral oxygenation, defined as a jugular bulb saturation less than 50%, between patients randomized to off-pump or (conventional) on-pump coronary artery surgery.

METHODS

One hundred and eighty-seven patients were assigned randomly to off-pump or on-pump coronary artery surgery. Oxygen saturation in the jugular bulb (SjO2) was measured during revascularization of the three main coronary vessels in the off-pump group, and at the start of CPB, before rewarming, and after rewarming in the on-pump group. We compared samples with jugular bulb with desaturation (SjO2) < or = 50%) between treatment groups.

RESULTS

One hundred and seventy-five patients (81 in the off-pump group [93%] and 94 in the on-pump group [94%]) had complete jugular oxygen saturation data. Thirty-nine patients in the off-pump group (48%) and 25 patients in the on-pump group (27%) had one or more samples with desaturation during revascularization or CPB (odds ratio after adjustment for other factors, 0.39; 95% confidence interval, 0.21-0.73, P<0.01).

CONCLUSION

Jugular bulb desaturation occurs more frequently during off-pump coronary artery surgery than during conventional coronary artery surgery.

Jugular Bulb Oxygen Saturation Under Propofol or Sevoflurane/Nitrous Oxide Anesthesia During Deliberate Mild Hypothermia in Neurosurgical Patients

Sevoflurane and propofol have been widely used as anesthetic agents for neurosurgery. Recent evidence has suggested that the influence of these anesthetics on cerebral oxygenation may differ. In the present study, the authors investigated jugular bulb oxygen saturation (SjO2) during propofol and sevoflurane/nitrous oxide anesthesia under mildly hypothermic conditions. After institutional approval and informed consent, 20 patients undergoing elective craniotomy were studied. Patients were randomly divided to the group S/N2O (sevoflurane/nitrous oxide/fentanyl anesthesia) or the group P (propofol/fentanyl anesthesia). After induction of anesthesia, the catheter was inserted retrograde into the jugular bulb and SjO2 was analyzed. During the operation, patients were cooled and tympanic membrane temperature was maintained at 34.5 degrees C. SjO2 was measured at normocapnia during mild hypothermia and at hypocapnia during mild hypothermia. There were no statistically significant differences in demographic variables between the groups. During mild hypothermia, SjO2 values were significantly lower in group P than in group S/N2O. The incidence of SjO2 less than 50% under mild hypothermic-hypocapnic conditions was significantly higher in group P than in group S/N2O. These results suggest that hyperventilation should be more cautiously applied during mild hypothermia in patients anesthetized with propofol and fentanyl versus sevoflurane/nitrous oxide/fentanyl.

Increasing mean arterial pressure improves jugular venous oxygen saturation in patients with and without preexisting stroke during normothermic cardiopulmonary bypass

STUDY OBJECTIVE

To examine whether increasing mean arterial pressure (MAP) with the administration of phenylephrine would improve internal jugular venous oxygen saturation (SjvO2) during normothermic cardiopulmonary bypass (CPB) in patients with preexisting stroke.

DESIGN

Prospective, controlled study.

SETTING

Cardiovascular center and university hospital.

PATIENTS

17 patients with preexisting stroke who were scheduled for elective coronary artery bypass graft (CABG) surgery, and a control group of 17 age-matched patients without preexisting stroke.

INTERVENTIONS

After the induction of anesthesia, a fiberoptic oximetry catheter was inserted into the right jugular bulb to monitor SjvO2. After measuring the baseline partial pressure of the arterial and jugular venous blood gases and cardiovascular hemodynamic values immediately before the start of the study protocol, MAP was increased by the repeated administration of a 10 microg bolus of phenylephrine, until it reached 200% of baseline values.

MEASUREMENTS

Partial pressure of the arterial and jugular venous blood gases and cardiovascular hemodynamic values before and after the treatment were recorded.

MAIN RESULTS

There was no significant difference between the groups in SjvO2 values at baseline (Mann-Whitney U test: p = 0.22). SjvO2 values in both groups were increased after the administration of phenylephrine (SjvO2 values in the control group: 60 +/- 5%, SjvO2 values in the stroke group: 57 +/- 5%). There was no significant difference between the stroke and control groups in SjvO2 values after the administration of phenylephrine (Mann-Whitney U test: p = 0.08).

CONCLUSIONS

Increasing MAP improves SjvO2 in patients with or without preexisting stroke during normothermic CPB.

Slow rewarming improves jugular venous oxygen saturation during rewarming

BACKGROUND

There have been many studies regarding the etiology of postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery. Although its etiology remains unresolved, one possible factor related to postoperative cognitive dysfunction is a reduced internal jugular venous oxygen hemoglobin saturation (SjvO2) during the rewarming period. The purpose of this study was to examine the effect of rewarming rates on SjvO2 during rewarming.

METHODS

One-hundred patients scheduled for elective CABG surgery were randomly divided into two groups; control group (0.48 +/- 0.09 degrees C, n = 50), slow rewarming group (0.24 +/- 0.09 degrees C, n = 50). After the induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to monitor SjvO2 continuously. Hemodynamic parameters, arterial and jugular venous blood gases were measured at nine time-points.

RESULTS

Cerebral desaturation (defined as a SjvO2 value below 50%) during rewarming was more frequent in the control group than in the slow group. Cerebral desaturation time (duration when SjvO2 was less than 50%) and the ratio of the cerebral desaturation time to the total CPB time in the control group differed significantly from those in the slow group (control group: 17 +/- 11 min, 12 +/- 4%, slow group: 10 +/- 8 min, 7 +/- 4%, respectively, P < 0.05). There was no significant difference in mini-mental state examination on the day before the operation nor at 1 month after the surgery among four values (the day before the operation: control group; 48 +/- 8, slow group; 48 +/- 7, at one month after the surgery: control group; 46 +/- 7, slow group; 45 +/- 9).

CONCLUSIONS

A slow rewarming rate could reduce the chance of a decrease in SjvO2 during rewarming.

Comparative effects of propofol versus fentanyl on cerebral oxygenation state during normothermic cardiopulmonary bypass and postoperative cognitive dysfunction

BACKGROUND

The purpose of this study was to examine the comparative effects of propofol and fentanyl on cerebral oxygenation during normothermic cardiopulmonary bypass and postoperative cognitive dysfunction.

METHODS

One hundred eighty patients scheduled for elective coronary artery bypass grafting were randomly divided into two groups: propofol group (n = 90) and fentanyl group (n = 90). After induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to monitor jugular venous oxygen hemoglobin saturation continuously. Hemodynamic measurements and arterial and jugular venous blood gases were measured at seven time points. All patients underwent a battery of neurologic and neuropsychological tests on the day before the operation and at 6 months after the operation.

RESULTS

Cerebral desaturation (defined as a jugular venous oxygen hemoglobin saturation value less than 50%) during cardiopulmonary bypass was more frequent in the fentanyl group than in the propofol group. Cerebral desaturation time (duration when jugular venous oxygen hemoglobin saturation was less than 50%) and the ratio of cerebral desaturation time to total cardiopulmonary bypass time in the fentanyl group differed significantly from those in the propofol group (fentanyl group: 27 +/- 14 minutes, 20% +/- 9%; propofol group: 18 +/- 11 minutes, 14% +/- 7%, respectively, p < 0.05). There was no significant difference in postoperative cognitive dysfunction at 6 months after operation between the two groups (propofol group: 5 of 77, 6%; fentanyl group: 5 of 75, 7%).

CONCLUSIONS

Propofol preserved cerebral oxygenation state estimated by jugular venous oxygenation during cardiopulmonary bypass compared with the fentanyl group. However, propofol did not affect postoperative cognitive dysfunction.

Comparison of alpha-stat and pH-stat cardiopulmonary bypass in relation to jugular venous oxygen saturation and cerebral glucose-oxygen utilization

Jugular venous oxygen saturation (SJVO(2)) reflects the balance between cerebral blood flow and metabolism. This study was designed to compare the effects of two different acid-base strategies on jugular venous desaturation (SJVO(2) <50%) and cerebral arteriovenous oxygen-glucose use. We performed a prospective, randomized study in 52 patients undergoing cardiopulmonary bypass (CPB) at 27 degrees C with either alpha-stat (n = 26) or pH-stat (n = 26) management. A retrograde internal jugular vein catheter was inserted, and blood samples were obtained at intervals during CPB. There were no differences in preoperative variables between the groups. SJVO(2) was significantly higher in the pH-stat group (at 30 min CPB: 86.2% +/- 6.1% versus 70.6% +/- 9.3%; P < 0.001). The differences in arteriovenous oxygen and glucose were smaller in the pH-stat group (at 30 min CPB: 1.9 +/- 0.82 mL/dL versus 3.98 +/- 1.12 mL/dL; P < 0.001; and 3.67 +/- 2.8 mL/dL versus 10.1 +/- 5.2 mL/dL; P < 0.001, respectively). All episodes of desaturation occurred during rewarming, and the difference in the incidence of desaturation between the two groups was not significant. All patients left the hospital in good condition. Compared with alpha-stat, the pH-stat strategy promotes an increase in SJVO(2) and a decrease in arteriovenous oxygen and arteriovenous glucose differences. These findings indicate an increased cerebral supply with pH-stat; however, this strategy does not eliminate jugular venous desaturation during CPB.

IMPLICATIONS

A prospective, randomized study in 52 patients during cardiopulmonary bypass revealed that pH-stat increased jugular venous oxygen saturation and decreased arteriovenous oxygen-glucose differences. There was no difference in the incidence of jugular venous desaturation. These findings suggest an increased cerebral blood flow with no protection against jugular venous desaturation during pH-stat.

Slow rewarming has no effects on the decrease in jugular venous oxygen hemoglobin saturation and long-term cognitive outcome in diabetic patients

The purpose of this study was to examine the effects of rewarming rate on internal jugular venous oxygen hemoglobin saturation (SjvO(2)) during the rewarming period, and long-term cognitive outcome in diabetic patients. We studied 30 diabetic patients scheduled for elective coronary artery bypass graft surgery. As a control, 30 age-matched nondiabetic patients were identified. The diabetic patients were randomly divided into two groups: the Slow Rewarming group (n = 15) (mean rewarming speed: 0.22 degrees +/- 0.07 degrees C/min, mean +/- SD) or the Standard Rewarming group (Standard group) (n = 15) (mean rewarming speed: 0.46 degrees +/- 0.09 degrees C/min, mean +/- SD). After the induction of anesthesia, a fiberoptic oximetry catheter was inserted into the right jugular bulb to monitor SjvO(2) continuously. Hemodynamic variables and arterial and jugular venous blood gases were measured at nine time points. All patients underwent a battery of neurologic and neuropsychologic tests on the day before the operation and at 4 mo after surgery. The SjvO(2) values in the Standard group were decreased during the rewarming period compared with at the induction of anesthesia (P < 0.05). There was a significant difference in the SjvO(2) value in the Control group between standard rewarming and slow rewarming during rewarming periods (Standard Control group: 51% +/- 8%, Slow Control groups: 58% +/- 5%) (P < 0.05). However, there was no difference in the SjvO(2) value in diabetic patients between standard rewarming and slow rewarming during the rewarming period. The rewarming rates (odds ratio: 0.8; 95% confidence interval: 0.5-1.3; P = 0.6) had no correlation with cognitive impairment at 4 mo after the surgery. Diabetes (odds ratio: 1.6; 95% confidence interval: 0.9-2.6; P = 0.04) was a factor in relation to cognitive impairment at 4 mo after the surgery. We concluded that a slow rewarming rate had no effects on the reduction in SjvO(2) value and long-term cognitive outcome in diabetic patients.

IMPLICATIONS

We examined the effects of rewarming rate on internal jugular venous oxygen hemoglobin saturation in diabetic and nondiabetic patients during the rewarming period and long-term cognitive outcome. Slow rewarming could not prevent the frequency of the reduction in internal jugular venous oxygen hemoglobin saturation and adverse cognitive outcome in diabetic patients.