Decrease in jugular venous oxygen saturation during normothermic cardiopulmonary bypass predicts short-term postoperative neurologic dysfunction in elderly patients

A Review of Monitoring Methods for Cerebral Blood Oxygen Saturation

In recent years, cerebral blood oxygen saturation has become a key indicator during the perioperative period. Cerebral blood oxygen saturation monitoring is conducive to the early diagnosis and treatment of cerebral ischemia and hypoxia. The present study discusses the three most extensively used clinical methods for cerebral blood oxygen saturation monitoring from different aspects: working principles, relevant parameters, current situations of research, commonly used equipment, and relative advantages of different methods. Furthermore, through comprehensive comparisons of the methods, we find that near-infrared spectroscopy (NIRS) technology has significant potentials and broad applications prospects in terms of cerebral oxygen saturation monitoring. Despite the current NIRS technology, the only bedside non-invasive cerebral oxygen saturation monitoring technology, still has many defects, it is more in line with the future development trend in the field of medical and health, and will become the main method gradually.

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.

Cerebral Perfusion and Brain Oxygen Saturation Monitoring with: Jugular Venous Oxygen Saturation, Cerebral Oximetry, and Transcranial Doppler Ultrasonography

Accumulating evidence indicates that cerebral desaturation in the perioperative period occurs more frequently than recognized. Combining monitoring modalities that reflect different aspects of cerebral perfusion status, such as near-infrared spectroscopy, jugular bulb saturation, and transcranial Doppler ultrasonography, may provide an extended window for prevention, early detection, and prompt intervention in ongoing hypoxic/ischemic neuronal injury and, thereby, improve neurologic outcome. Such an approach would minimize the impact of limitations of each monitoring modality, while individual components complement each other, enhancing the accuracy of acquired information. Current literature has failed to demonstrate any clear-cut clinical benefit of these modalities on outcome prognosis.

Risk Factors for Delirium and Cognitive Decline Following Coronary Artery Bypass Grafting Surgery: A Systematic Review and Meta-Analysis

Background

Coronary artery bypass grafting (CABG) is known to improve heart function and quality of life, while rates of surgery‐related mortality are low. However, delirium and cognitive decline are common complications. We sought to identify preoperative, intraoperative, and postoperative risk or protective factors associated with delirium and cognitive decline (across time) in patients undergoing CABG.

Methods and Results

We conducted a systematic search of Medline, PsycINFO, EMBASE, and Cochrane (March 26, 2019) for peer‐reviewed, English publications reporting post‐CABG delirium or cognitive decline data, for at least one risk factor. Random‐effects meta‐analyses estimated pooled odds ratio for categorical data and mean difference or standardized mean difference for continuous data. Ninety‐seven studies, comprising data from 60 479 patients who underwent CABG, were included. Moderate to large and statistically significant risk factors for delirium were as follows: (1) preoperative cognitive impairment, depression, stroke history, and higher European System for Cardiac Operative Risk Evaluation (EuroSCORE) score, (2) intraoperative increase in intubation time, and (3) postoperative presence of arrythmia and increased days in the intensive care unit; higher preoperative cognitive performance was protective for delirium. Moderate to large and statistically significant risk factors for acute cognitive decline were as follows: (1) preoperative depression and older age, (2) intraoperative increase in intubation time, and (3) postoperative presence of delirium and increased days in the intensive care unit. Presence of depression preoperatively was a moderate risk factor for midterm (1–6 months) post‐CABG cognitive decline.

Conclusions

This meta‐analysis identified several key risk factors for delirium and cognitive decline following CABG, most of which are nonmodifiable. Future research should target preoperative risk factors, such as depression or cognitive impairment, which are potentially modifiable.

Registration

URL: https://www.crd.york.ac.uk/prosp​ero/; Unique identifier: CRD42020149276.

Electroencephalography and Brain Oxygenation Monitoring in the Perioperative Period

Maintaining brain function and integrity is a pivotal part of anesthesiological practice. The present overview aims to describe the current role of the 2 most frequently used monitoring methods for evaluation brain function in the perioperative period, ie, electroencephalography (EEG) and brain oxygenation monitoring. Available evidence suggests that EEG-derived parameters give additional information about depth of anesthesia for optimizing anesthetic titration. The effects on reduction of drug consumption or recovery time are heterogeneous, but most studies show a reduction of recovery times if anesthesia is titrated along processed EEG. It has been hypothesized that future EEG-derived indices will allow a better understanding of the neurophysiological principles of anesthetic-induced alteration of consciousness instead of the probabilistic approach most often used nowadays.Brain oxygenation can be either measured directly in brain parenchyma via a surgical burr hole, estimated from the venous outflow of the brain via a catheter in the jugular bulb, or assessed noninvasively by near-infrared spectroscopy. The latter method has increasingly been accepted clinically due to its ease of use and increasing evidence that near-infrared spectroscopy-derived cerebral oxygen saturation levels are associated with neurological and/or general perioperative complications and increased mortality. Furthermore, a goal-directed strategy aiming to avoid cerebral desaturations might help to reduce these complications. Recent evidence points out that this technology may additionally be used to assess autoregulation of cerebral blood flow and thereby help to titrate arterial blood pressure to the individual needs and for bedside diagnosis of disturbed autoregulation.

Sex and genetic differences in postoperative cognitive dysfunction: a longitudinal cohort analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common postoperative complication experienced by patients aged 65 years and older, and these older adults comprise more than one third of the surgical patients in the USA. Because not everyone with a history of exposure to surgery and anesthesia develops POCD, there are likely major biological risk factors involved. There are important gaps in our knowledge regarding whether genetic makeup, biological sex, or other Alzheimer's disease risk factors predispose older adults to developing POCD. We set out to determine whether biological sex and Apolipoprotein E-ε4 (APOE4) carrier status increase the risk of developing POCD in older adults.

METHODS

We performed a cohort analysis of 1033 participants of prospective longitudinal aging studies. Participants underwent regular cognitive test batteries and we compared the annual rate of change over time in various cognitive measures in the women exposed to surgery and general anesthesia compared to the men exposed to surgery and general anesthesia. Mixed-effects statistical models were used to assess the relationship between biological sex, APOE4 carrier status, surgery and anesthesia exposure, and the rate of change in cognitive test scores.

RESULTS

When comparing all men (n = 89) and women (n = 164) who had surgery, there were no significant sex differences in postoperative cognitive outcomes. However, men with an APOE4 allele performed significantly worse on cognitive testing following surgery and anesthesia than women APOE4 carriers, even after adjusting for age, education level, and comorbidities.

CONCLUSIONS

Older men with APOE4 allele may be more vulnerable to postoperative cognitive dysfunction than older women with APOE4 allele.

Temperature Variation After Rewarming from Deep Hypothermic Circulatory Arrest Is Associated with Survival and Neurologic Outcome

Therapeutic hypothermia is recommended by international guidelines after cardio-circulatory arrest. However, the effects of different temperatures during the first 24 hours after deep hypothermic circulatory arrest (DHCA) for aortic arch surgery on survival and neurologic outcome are undefined. We hypothesize that temperature variation after aortic arch surgery is associated with survival and neurologic outcome. In the period 2010-2014, a total of 210 consecutive patients undergoing aortic arch surgery with DHCA were included. They were retrospectively divided into three groups by median nasopharyngeal temperature within 24 hours after rewarming: hypothermia (<36°C; n = 65), normothermia (36-37°C; n = 110), and hyperthermia (>37°C; n = 35). Multivariate stepwise logistic and linear regressions were performed to determine whether different temperature independently predicted 30-day mortality, stroke incidence, and neurologic outcome assessed by cerebral performance category (CPC) at hospital discharge. Compared with normothermia, hyperthermia was independently associated with a higher risk of 30-day mortality (28.6% vs. 10.9%; odds ratio [OR] 2.8; 95% confidence interval [CI], 1.1-8.6; p = 0.005), stroke incidence (64.3% vs. 9.1%; OR 9.1; 95% CI, 2.7-23.0; p = 0.001), and poor neurologic outcome (CPC 3-5) (68.8% vs. 39.6%; OR 4.8; 95% CI, 1.4-8.7; p = 0.01). No significant differences were demonstrated between hypothermia and normothermia. Postoperative hypothermia is not associated with a better outcome after aortic arch surgery with DHCA. However, postoperative hyperthermia (>37°C) is associated with high stroke incidence, poor neurologic outcome, and increased 30-day mortality. Target temperature management in the first 24 hours after surgery should be evaluated in prospective randomized trials.

A comparative analysis of the effects of sevoflurane and propofol on cerebral oxygenation during steep Trendelenburg position and pneumoperitoneum for robotic-assisted laparoscopic prostatectomy

Purpose

Steep Trendelenburg position and pneumoperitoneum during robotic-assisted laparoscopic prostatectomy (RALP) increase intracranial pressure (ICP) and may alter cerebral blood flow (CBF) and oxygenation. Volatile anesthetics and propofol have different effects on ICP, CBF, and cerebral metabolic rate and may have different impact on cerebral oxygenation during RALP. In this study, we measured jugular venous bulb oxygenation (SjO₂) and regional oxygen saturation (SctO₂) in patients undergoing RALP to evaluate cerebral oxygenation and compared the effects of sevoflurane and propofol. We also verified whether SctO₂ may be an alternative to SjO₂.

Methods

Fifty patients scheduled for RALP were randomly assigned to undergo sevoflurane (group S) or propofol (group P) anesthesia. SjO₂, SctO₂, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), central venous pressure (CVP), partial pressures of arterial oxygen (PaO₂) and carbon dioxide (PaCO₂), hemoglobin concentration (Hb), Bispectral Index (BIS) and nasopharyngeal temperature (BT) were recorded 5 min before surgery commencement, 5 min after pneumoperitoneum, 5, 30, 60, 90, and 120 min after pneumoperitoneum in a Trendelenburg position, and after desufflation in a supine position.

Results

SjO₂ was significantly higher in group S than in group P at all measurement points [group S vs. group P: 77 % (11) vs. 65 % (13), mean of all measurement points (1SD); p < 0.01]. Linear regression analysis (β = 0.106; r² = 0.065; p = 0.004) shows a weak relationship between SjO₂ and SctO₂.

Conclusions

Sevoflurane maintains higher SjO₂ levels than propofol during RALP. SctO₂ does not accurately reflect SjO₂.

Effect of slow versus rapid rewarming on jugular bulb oxygen saturation in adult patients undergoing open heart surgery

BACKGROUND

A debate has appeared in the recent literature about the optimum rewarming strategy (slow vs. rapid) for the best brain function. This study was designed to compare the effect of slow versus rapid rewarming on jugular bulb oxygen saturation (SjO2) in adult patients undergoing open heart surgery.

MATERIALS AND METHODS

A total of 80 patients undergoing valve and adult congenital heart surgery were randomly allocated equally to rapid rewarming group 0.5 (0.136)°C/min and slow rewarming group 0.219 (0.055)°C/min in jugular bulb sampling was taken before, during and after surgery. Surgery was done at cardiopulmonary bypass (CPB) temperature of 28-30°C and rewarming was performed at the end of the surgical procedure.

RESULTS

CPB time, rewarming period were significantly longer in the slow rewarming group. Significant difference was observed in the number of the desaturated patients (SjO2 ≤ 50%) between the two groups; 14 (35%) in rapid rewarming versus 6 (15%) in the slow rewarming group; P = 0.035 by Fisher's exact test.

CONCLUSIONS

Slow rewarming could reduce the incidence of SjO2 desaturation during rewarming in adult patients undergoing open heart surgery.

Milrinone, a phosphodiesterase III inhibitor, prevents reduction of jugular bulb saturation during rewarming from hypothermic cardiopulmonary bypass

Introduction: Inadequate cerebral oxygen balance during cardiopulmonary bypass may cause neuropsychological dysfunction. Milrinone, a phosphodiesterase III inhibitor, augments cerebral blood flow by direct vasodilatation. We conducted a prospective, randomized study in patients undergoing cardiac surgery with cardiopulmonary bypass to clarify the clinical efficacy of milrinone in the imbalance of cerebral oxygen supply and demand during the rewarming period of cardiopulmonary bypass.

Methods: This is a prospective, randomized and placebo-controlled study. After anesthesia, a 5.5 F fiberoptic oximeter catheter was inserted into the right jugular bulb retrogradely for monitoring the jugular venous oxyhemoglobin saturation (SjO2). Patients were randomly assigned to two groups, one receiving a continuous infusion of milrinone, 0.5 µg/kg/min during hypothermic cardiopulmonary bypass, and the other receiving saline as control.

Results: Milrinone significantly prevented the reduction of the jugular venous oxyhemoglobin saturation at 10 minutes from the start of rewarming compared with the control group, but did not do so from 10 to 20 minutes after rewarming.

Conclusion: Milrinone suppresses the reduction of SjO2 and improves the balance of cerebral oxygen supply and demand during the early rewarming period of hypothermic cardiopulmonary bypass.

Association between cerebrovascular carbon dioxide reactivity and postoperative short-term and long-term cognitive dysfunction in patients with diabetes mellitus

PURPOSE

Our intent was to identify whether cerebrovascular CO(2) reactivity in diabetic patients is a risk factor for postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery.

METHODS

One hundred twenty-four diabetic patients undergoing elective CABG were studied and analyzed. Diabetic patients were divided into three groups: normal CO(2) reactivity group (above 5%/mmHg), medium CO(2) reactivity group (between 5 and 3%/mmHg), or impaired CO(2) reactivity group (below 3%/mmHg). After the induction of anesthesia and before the start of surgery, cerebrovascular CO(2) reactivity was measured for all patients. Hemodynamic parameters (arterial and jugular venous blood gas values) were measured during cardiopulmonary bypass. All patients underwent a battery of neurological and neuropsychological tests the day before surgery, 7 days after surgery, and 6 months after surgery.

RESULTS

At 7 days, the rate of cognitive dysfunction in the impaired CO(2) group was higher than in the other three groups (normal, 30%; medium, 25%; impaired, 57%; *P < 0.01 compared with the other groups). In contrast, at 6 months postoperatively, no significant difference in the rate of cognitive dysfunction was found among the three groups. Age, hypertension, CO(2) reactivity, the duration for which jugular venous oxygen saturation (SjvO(2)) was less than 50%, ascending aorta atherosclerosis, diabetic retinopathy, and insulin therapy were independent predictors of short-term cognitive dysfunction in diabetic patients, and HbA1c, diabetic retinopathy, and insulin therapy were independent predictors of long-term cognitive dysfunction in diabetic patients.

CONCLUSIONS

We found that impaired cerebrovascular CO(2) reactivity was associated with postoperative short-term cognitive dysfunction in diabetic patients.

Effect of olprinone, a phosphodiesterase III inhibitor, on balance of cerebral oxygen supply and demand during cardiopulmonary bypass

Neuropsychological dysfunction with cardiopulmonary bypass (CPB) may be facilitated by inadequate cerebral oxygen balance during CPB. Olprinone, a phosphodiesterase III inhibitor, augments cerebral blood flow by a direct vasodilator effect on cerebral arteries. We conducted the present randomized study in patients undergoing cardiac surgery with CPB to investigate whether olprinone improved the balance of cerebral oxygen supply and demand during the rewarming period of CPB. After anesthesia, a 5.5 F fiberoptic oximeter catheter was inserted into the right jugular bulb retrogradely for monitoring the jugular venous oxyhemoglobin saturation (SjO2), and a probe of transcranial near-infrared spectroscopy was placed over the forehead for monitoring the bilateral regional cerebral oxygen saturation (rSO2). Patients were randomly assigned to 3 groups, and olprinone was administered at 0, 0.2, or 0.4 μg·kg(-1)·min(-1) after establishment of hypothermic CPB. Olprinone significantly prevented the reduction of the SjO2 at 5 and 10 minutes after the start of rewarming, although it did not alter rSO2. Furthermore, there was a minor reduction of the bilateral rSO2 at low doses of olprinone (0.2 μg·kg(-1)·min(-1)). We conclude that olprinone prevents the decrease of the SjO2 at the rewarming period and improves the balance of cerebral oxygen supply and demand during the rewarming period of CPB. In addition, a future extended study may be required to elucidate the effect of low dose of olprinone.

Preoperative depression is a risk factor for postoperative short-term and long-term cognitive dysfunction in patients with diabetes mellitus

PURPOSE

To identify whether the presence of preoperative depression in patients with diabetes mellitus is a risk factor for postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery.

METHODS

Data from 90 patients with diabetes mellitus undergoing elective CABG were analyzed. Hemodynamic data (arterial and jugular venous blood gas values) were measured during cardiopulmonary bypass. Preoperatively, all patients were given the 21-item Beck depression inventory to identify the presence of depression. In addition, all patients underwent a battery of neurological and neuropsychological tests the day before surgery, 7 days after surgery, and 6 months after surgery.

RESULTS

The rate of cognitive dysfunction was 50% at 7 days and 23% at 6 months after surgery. Age, hypertension, presence of depression, duration of SjvO(2) ≤ 50%, ascending aorta atherosclerosis, diabetic retinopathy, and insulin therapy were independent predictors of short-term cognitive dysfunction, whereas HbA1c, diabetic retinopathy, insulin therapy, and presence of depression were independent predictors of long-term cognitive dysfunction.

CONCLUSIONS

We found that the presence of depression preoperatively is associated with short-term and long-term postoperative cognitive dysfunction in patients with diabetes mellitus.

Anesthetic considerations in diabetic patients. Part I: preoperative considerations of patients with diabetes mellitus

Diabetes mellitus is an increasingly common disease that affects people of all ages, resulting in significant morbidity and mortality. Diabetic patients require perioperative care more frequently than their nondiabetic counterparts. The major risk factors for diabetics undergoing surgery are the associated end-organ diseases: cardiovascular disease, autonomic neuropathy, joint collagen tissue, and immune deficiency. Physicians need to pay extra attention to preoperative and preprocedure evaluation and treatment of these diseases to ensure optimal perioperative management.

Phenylephrine but not ephedrine reduces frontal lobe oxygenation following anesthesia-induced hypotension

BACKGROUND

Vasopressor agents are used to correct anesthesia-induced hypotension. We describe the effect of phenylephrine and ephedrine on frontal lobe oxygenation (S(c)O(2)) following anesthesia-induced hypotension.

METHODS

Following induction of anesthesia by fentanyl (0.15 mg kg(-1)) and propofol (2.0 mg kg(-1)), 13 patients received phenylephrine (0.1 mg iv) and 12 patients received ephedrine (10 mg iv) to restore mean arterial pressure (MAP). Heart rate (HR), MAP, stroke volume (SV), cardiac output (CO), and frontal lobe oxygenation (S(c)O(2)) were registered.

RESULTS

Induction of anesthesia was followed by a decrease in MAP, HR, SV, and CO concomitant with an elevation in S(c)O(2). After administration of phenylephrine, MAP increased (51 +/- 12 to 81 +/- 13 mmHg; P < 0.001; mean +/- SD). However, a 14% (from 70 +/- 8% to 60 +/- 7%) reduction in S(c)O(2) (P < 0.05) followed with no change in CO (3.7 +/- 1.1 to 3.4 +/- 0.9 l min(-1)). The administration of ephedrine led to a similar increase in MAP (53 +/- 9 to 79 +/- 8 mmHg; P < 0.001), restored CO (3.2 +/- 1.2 to 5.0 +/- 1.3 l min(-1)), and preserved S(c)O(2).

CONCLUSIONS

The utilization of phenylephrine to correct hypotension induced by anesthesia has a negative impact on S(c)O(2) while ephedrine maintains frontal lobe oxygenation potentially related to an increase in CO.

Diabetes mellitus does not affect jugular bulb oxygen saturation in patients undergoing off-pump coronary artery bypass graft surgery

BACKGROUND

Diabetes mellitus (DM) is associated with the impairment of cerebral oxygenation during cardiac surgery. The aim of the present study was to investigate the effects of DM on cerebral oxygenation assessed by jugular bulb oxygen saturation (SjvO2) in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB) in a prospective controlled trial.

METHODS AND RESULTS

Twenty-three diabetic patients with glycosylated hemoglobin above 7.0% (DM group) and 23 non-diabetic patients (control group) undergoing OPCAB with no-touch aortic technique were included. A fiberoptic oximetry catheter was inserted into the jugular bulb. The lowest SjvO2 and the number of patients with cerebral desaturation, defined as SjvO2 less than 50% over 5 min, were recorded during coronary grafting. Three neurocognitive tests were done before surgery and at postoperative day 2 and 7. There were no differences in SjvO2 between the groups. Furthermore, the number of patients with cerebral desaturation and all neurocognitive test scores were similar between the 2 groups. None of the patients developed neurocognitive dysfunction.

CONCLUSIONS

Cerebral oxygenation in diabetic patients was similar to that of non-diabetic patients and well maintained above the critical level without resulting in clinically significant postoperative neurocognitive dysfunction during OPCAB with no-touch aortic technique.

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.

Assessment of moderate to severe abdominal blood loss using peripheral to central blood oxygen saturation

PURPOSE

There are various definitions and monitoring modalities for hemodynamic status. Each of them has its own advantages and shortcomings. A new hemodynamic index is proposed in this study. This index can be calculated by placing the measured hemoglobin saturation in a formula. Blood samples for this measurement are taken from arterial, antecubital and central venous blood.

MATERIAL AND METHODS

We calculated this index in three different groups undergoing laparatomy. The control group consisted of patients who underwent elective surgery. The case group with acute internal abdominal bleeding was divided into two groups. Those with more than 20 ml/kg of blood in their abdominal cavity were designated as the severe case group, while those bleeding less were categorized as moderate. Blood samples were taken from ten patients in each group in stable and unstable conditions.

RESULTS

This index differed significantly between dissimilar hemodynamic conditions. The pre-anesthesia value of this index in the control group showed a mean +/- SD of 8.5 +/- 3.2 vs. 1.6 +/- 0.4 in the moderate case group vs. 0.7 +/- 0.08 in the case group with severe hemodynamic changes (p < .001). The index approximated to the control values as the circumstances improved. After compensation for volume loss, pre-extubation values were not significantly different. These were 9.6 +/- 2 in the control group vs. 8 +/- 2 in the case group with moderate hemodynamic change vs. 8 +/- 1.8 in the severe case group. The likelihood ratio of bleeding increased as this index decreased.

CONCLUSION

As the hemodynamic condition deteriorates, this index decreases significantly. This index is an accurate indicator for predicting hemodynamic changes compared to some other modalities. Further investigations are needed into the prognostic and therapeutic advantages of this index.

Increased cerebral and renal endothelial nitric oxide synthase gene expression after cardiopulmonary bypass in the rat

OBJECTIVE

Hemodilution and endothelial nitric oxide synthase genetic polymorphism may contribute to cerebral and renal injury after cardiopulmonary bypass. This study tested the hypothesis that cardiopulmonary bypass and anemia stimulate an increase in cerebral and renal endothelial nitric oxide synthase gene expression in an experimental model of cardiopulmonary bypass.

METHODS

Anesthetized rats underwent a sham procedure without cardiopulmonary bypass (sham, n = 5), normothermic bypass for 1 hour (CPB, n = 7), or bypass plus hemodilutional anemia (CPB anemia, n = 9). After 24 hours of recovery, RNA was extracted from the cerebral cortex, renal cortex, and renal medulla. Quantitative reverse transcriptase polymerase chain reaction was used to assess endothelial nitric oxide synthase messenger RNA levels in brain and kidney tissues.

RESULTS

The hemoglobin concentration of anemic CPB rats was significantly lower than that of nonanemic rats on bypass (64 +/- 5 vs 99 +/- 8 g x L(-1), P < .001). Cerebral cortical endothelial nitric oxide synthase messenger RNA levels were increased after cardiopulmonary bypass relative to those of the sham group (11.2 +/- 4.2 vs 6.3 +/- 1.5 fg, P = .031), without a further increase in anemic rats. Renal medullary endothelial nitric oxide synthase messenger RNA levels were significantly higher in the CPB anemia group than in the sham and CPB groups (7.1 +/- 4.4 fg vs 1.8 +/- 0.4 fg vs 3.0 +/- 0.6 fg, P < .001). Renal cortical endothelial nitric oxide synthase messenger RNA levels did not change significantly.

CONCLUSIONS

Normothermic cardiopulmonary bypass was associated with higher endothelial nitric oxide synthase messenger RNA levels in kidney and brain than was the sham procedure 24 hours after cardiopulmonary bypass. Anemia accentuated the increase in renal medullary, but not cerebral cortical, endothelial nitric oxide synthase expression. These data provide an approach for exploring potential mechanisms by which endothelial nitric oxide synthase may contribute to renal and cerebral dysfunction after cardiopulmonary bypass and anemia.

Factors associated with postoperative cognitive dysfunction in patients undergoing cardiac surgery

PURPOSE

Central nervous system complications continue to be major causes of morbidity and mortality after cardiac surgery. The purpose of this study was to identify the risk factors for postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery.

METHODS

Eighty-eight patients scheduled for elective CABG were studied. After the induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb for the continuous monitoring of jugular venous oxygen hemoglobin saturation (SjvO(2)). The hemodynamic parameters and arterial and jugular venous blood gases were measured during cardiopulmonary bypass (CPB). All patients underwent a battery of neurological and neuropsychological tests one day before the operation and at 6 months after the operation.

RESULTS

The incidence of a cognitive decline at 6 months was 24/88 (27.3%). Greater age (P = 0.04), the presence of renal failure (P < 0.001), and diabetes mellitus (P < 0.001) were more frequent in the patients with postoperative cognitive dysfunction at 6 months after the operation than in patients without cognitive dysfunction. Age (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.0-1.7; P = 0.04), diabetes mellitus (OR, 1.8; 95% CI, 1.2-2.4; P < 0.01), and presence of renal failure (OR, 2.8; 95% CI, 2.4-4.3; P < 0.01) were associated with cognitive impairment at 6 months postoperatively. However, there was no relationship between the presence of atherosclerosis in the ascending aorta and postoperative cognitive dysfunction after CABG surgery.

CONCLUSIONS

A greater age, diabetes mellitus, and renal failure were found to be risk factors for development of cognitive impairment at 6 months after CABG with CPB.

Lower limits of hematocrit and mixed venous oxygen saturation ensuring sufficient cerebral oxygenation during hemodilution in rabbits

OBJECTIVES

We have assessed clinically systemic tissue oxygenation by monitoring mixed venous oxygen saturation (SvO2) in addition to hematocrit (Hct) during cardiopulmonary bypass. Based on results of experimental studies together with clinical experience, we previously defined the lower limits of the critical range as an Hct of 12% and an SvO2 of 46%. However, these values do not provide direct information about cerebral oxygenation. This study was performed to identify critical values for these variables that would be able to ensure sufficient jugular venous oxygen saturation (SjO2), which reflects global cerebral oxygenation.

METHODS

Normovolemic hemodilution was performed in ten rabbits. Hct, SvO2 and SjO2 were measured every 7 minutes. The safety limit for cerebral oxygenation was defined as an SjO2 of 50% based on studies of Croughwell et al. and Cook et al. The limit point was defined as 7 minutes before the time that the SjO2 decreased below 50% for the first time.

RESULTS

Minimal values for Hct and SvO2 to maintain SjO2 at 50% or more during normovolemic normothermic hemodilution, expressed as the 95% confidence interval, were Hct of 7.4% to 10.0% and SvO2 of 41.8% to 51.4%.

CONCLUSION

Adopting the higher values of these pairs, safety limits for cerebral oxygenation would be an Hct of 10.0% and an SvO2 of 51.4%. In conclusion, our experiments in rabbits suggest new safety limits during normovolemic normothermic hemodilution of Hct of 12% and SvO2 of 52%, taking both whole-body and cerebral oxygenation into consideration.

Analysis of the factors related to a decrease in jugular venous oxygen saturation in patients with diabetes mellitus during normothermic cardiopulmonary bypass

PURPOSE

We sought to examine what factors, including cerebrovascular carbon dioxide (CO(2)) reactivity, are related to a decrease in internal jugular venous oxygen saturation (SjvO(2)) during normothermic cardiopulmonary bypass (CPB) in patients with diabetes mellitus.

METHODS

Twenty-three diabetic patients scheduled to undergo elective coronary artery bypass grafting were studied. As a control, 27 age-matched control patients without diabetes mellitus were also examined. After the induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to continuously monitor SjvO(2). Arterial and jugular venous blood gases were measured during CPB. The cerebrovascular CO(2) reactivity was measured after the induction of anesthesia and before the start of surgery using a 2.5-MHz pulsed transcranial Doppler probe.

RESULTS

The SjvO(2) values in the diabetic group were lower than those in the control group at the initiation of CPB and at 20, 40, and 60 min after the start of CPB. The values for pre- and post-CO(2) reactivity in the control group did not significantly differ (pre-CPB: 4.8% +/- 2.3% mmHg(-1); post-CPB: 5.9% +/- 4.4% mmHg(-1)). In contrast, the values for CO(2) reactivity were lower post CPB than pre-CPB in the diabetic group (Pre-CPB: 6.3% +/- 2.9% mmHg(-1); post-CPB: 4.7% +/- 2.6% mmHg(-1); P < 0.05). In the diabetic group, glycosylated hemoglobin A1c (HbA1c) is considered to be a factor related to a decrease in SjvO(2) during CPB.

CONCLUSIONS

Cerebrovascular CO(2) reactivity in diabetic patients decreased after the cessation of CPB but not in the control patients. In addition, HbA1c is also thought to be a factor related to a decrease in SjvO(2) in diabetic patients.

Changes in jugular bulb oxygen saturation during off-pump coronary artery bypass graft surgery

BACKGROUND

The effect of haemodynamic derangement during coronary artery anastomosis in off-pump coronary artery bypass surgery on cerebral blood flow has not been elucidated. Jugular bulb oxygen saturation is a useful indicator of cerebral blood flow provided that the cerebral metabolic rate is constant. This study was designed to evaluate the changes in jugular bulb oxygen saturation during off-pump coronary artery bypass surgery.

METHODS

With IRB approval, 48 patients were included. After anaesthesia, an 18-G catheter was introduced into the jugular bulb. Haemodynamic variables and oxygen profiles from gas analysis of jugular bulb blood and arterial blood were obtained: after sternotomy (baseline); at 5 min after the beginning of the anastomosis of the left anterior descending artery, obtuse marginal artery, and right coronary artery; and after sternal closure.

RESULTS

Cardiac index and mixed venous oxygen saturation decreased significantly during anastomosis of all three arteries compared to the baseline value. Although the changes in jugular bulb oxygen saturation during anastomosis were statistically significant compared to its baseline value, jugular bulb oxygen saturation remained within normal limit throughout the study.

CONCLUSIONS

Jugular bulb oxygen saturation, which represents the global cerebral oxygenation, was well maintained during the anastomosis of all coronary arteries despite significant haemodynamic changes during off-pump coronary artery bypass (OPCAB).

Risk factors for cognitive dysfunction after coronary artery bypass graft surgery in patients with type 2 diabetes

OBJECTIVES

The mechanisms of postoperative cognitive dysfunction in patients with diabetes after coronary artery bypass grafting are not fully understood. We sought to determine which type 2 diabetes-related factors contributed to postoperative cognitive dysfunction at 7 days and 6 months after coronary artery bypass grafting.

METHODS

One hundred eighty patients with type 2 diabetes who were scheduled for elective coronary artery bypass grafting were studied. As a control group, 100 patients without diabetes mellitus matched for age, sex, and educational level were examined. Hemodynamic parameters (arterial and jugular venous blood gas values) were measured during cardiopulmonary bypass. All patients underwent a battery of neurologic and neuropsychologic tests the day before surgery, 7 days after surgery, and 6 months after surgery.

RESULTS

Age (odds ratio 1.5, 95% confidence interval 1.3-1.8, P = .03), presence of hypertension (odds ratio 1.8, 95% confidence interval 1.3-2.0, P = .01), jugular venous oxygen saturation less than 50% time (odds ratio 1.5, 95% confidence interval 1.1-2.0, P = .045), presence of ascending aorta atherosclerosis (odds ratio 1.5, 95% confidence interval 1.1-2.6, P = .01), diabetic retinopathy (odds ratio 2.0, 95% confidence interval 1.3-3.0, P = .01), and insulin therapy (odds ratio 2.0, 95% confidence interval 1.3-3.0, P = .05), were associated with cognitive impairment at 7 days. Insulin therapy (odds ratio 2.0, 95% confidence interval 1.3-3.8, P = .01), diabetic retinopathy (odds ratio 1.3, 95% confidence interval 1.2-2.9, P < .01), and hemoglobin A 1c (odds ratio 1.9, 95% confidence interval 1.3-3.1, P = .047) were associated with cognitive impairment at 6 postoperative months.

CONCLUSIONS

Insulin therapy, diabetic retinopathy, and hemoglobin A 1c were factors in cognitive impairment at 7 days and 6 months after coronary artery bypass grafting in patients with type 2 diabetes.

Cerebrovascular carbon dioxide reactivity with propofol anesthesia in patients with previous stroke

STUDY OBJECTIVE

To examine whether patients with previous stroke have impaired cerebrovascular carbon dioxide (CO2) reactivity when receiving propofol anesthesia.

DESIGN

Prospective, controlled study.

SETTING

University hospital.

PATIENTS

34 consecutive patients, 17 of whom had previous stroke and were scheduled for elective cardiac surgery, and 17 control age-matched patients without previous stroke who were also scheduled for cardiac surgery.

INTERVENTIONS

Anesthesia was induced and a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window. Mean blood flow velocity of the middle cerebral artery (Vmca) was measured continuously.

MEASUREMENTS

After establishing baseline Vmca, arterial blood gases and cardiovascular hemodynamic values, partial pressure of end-tidal CO2 (PETCO2) was increased by changing the ventilatory frequency by 2 to 5 breaths/min. The measurements were repeated when PETCO2 increased and remained stable for 5 to 10 minutes.

MAIN RESULTS

Values for absolute CO2 reactivity in the control patients and in those with previous stroke were 2.6 +/- 0.5 and 2.9 +/- 0.7 cm/sec/mmHg, respectively, a nonsignificant difference in these values. Values for relative CO2 reactivity in control patients and in patients with previous stroke were 6.4 +/- 1.4 and 6.1 +/- 1.4%/mmHg, respectively, with no significant difference noted.

CONCLUSIONS

Cerebrovascular CO2 reactivity in patients with previous stroke is normal during propofol anesthesia.

Cerebral oxygen desaturation is associated with early postoperative neuropsychological dysfunction in patients undergoing cardiac surgery

OBJECTIVE

To evaluate the relationship between cerebral oxygen saturation and neuropsychological dysfunction after cardiac surgery.

DESIGN

Prospective and observational study.

SETTING

Operating room and cardiac floor of a university hospital.

PARTICIPANTS

One hundred one patients undergoing elective cardiac surgery with cardiopulmonary bypass

INTERVENTION

Bilateral noninvasive cerebral oxygen saturations were monitored over the forehead. The anesthetic and surgical techniques were performed as usual, and no interventions were attempted based on the monitor. Neuropsychological outcome was assessed by the Mini-Mental State Examination (MMSE) and the antisaccadic eye movement test (ASEM).

MEASUREMENTS AND MAIN RESULTS

Preoperative baseline values of cerebral oxygen saturation (rSO(2)) were 58.6% +/- 10.2%. Patients with the nadir rSO(2) <35% had significantly higher incidences of postoperative ASEM and MMSE impairments than those with rSO(2) always above 35% (44% and 33% v 12% and 9%, respectively). Patients with areas of rSO(2) <40% for more than 10 minutes . % presented with a significantly higher incidence of postoperative ASEM and MMSE impairments than those with areas of rSO(2) <40% for less than 10 minutes . % (42% and 32% v 13% and 10%, respectively). Patients with postoperative ASEM or MMSE impairment had significantly lower nadir rSO(2) and significantly larger areas of rSO(2) <40%, <45%, and <50% than those with normal postoperative neuropsychological outcome. However, multivariate logistic regression analysis showed that areas of rSO(2) <40% were the only predictor for both postoperative ASEM and MMSE impairments.

CONCLUSIONS

Intraoperative cerebral oxygen desaturation is associated with early postoperative neuropsychological dysfunction in patients undergoing cardiac surgery with cardiopulmonary bypass. However, it remains to be determined whether interventions to maintain adequate cerebral oxygenation may improve neuropsychological outcome.

Prevention of Cerebral Hyperthermia During Cardiac Surgery by Limiting On-Bypass Rewarming in Combination with Post-Bypass Body Surface Warming: A Feasibility Study

Cerebral hyperthermia is common during the rewarming phase of cardiopulmonary bypass (CPB) and is implicated in CPB-associated neurocognitive dysfunction. Limiting rewarming may prevent cerebral hyperthermia but risks postoperative hypothermia. In a prospective, controlled study, we tested whether using a surface-warming device could allow limited rewarming from hypothermic CPB while avoiding prolonged postoperative hypothermia (core body temperature <36 degrees C). Thirteen patients undergoing primary elective coronary artery bypass grafting surgery were randomized to either a surface-rewarming group (using the Arctic Sun thermoregulatory system; n = 7) or a control standard rewarming group (n = 6). During rewarming from CPB, the control group was warmed to a nasopharyngeal temperature of 37 degrees C, whereas the surface-warming group was warmed to 35 degrees C, and then slowly rewarmed to 36.8 degrees C over the ensuing 4 h. Cerebral temperature was measured using a jugular bulb thermistor. Nasopharyngeal temperatures were lower in the surface-rewarming group at the end of CPB but not 4 h after surgery. Peak jugular bulb temperatures during the rewarming phase were significantly lower in the surface-rewarming group (36.4 degrees C +/- 1 degrees C) compared with controls (37.7 degrees C +/- 0.5 degrees C; P = 0.024). We conclude that limiting rewarming during CPB, when used in combination with surface warming, can prevent cerebral hyperthermia while minimizing the risk of postoperative hypothermia[corrected].

The effect of diabetes on the interrelationship between jugular venous oxygen saturation responsiveness to phenylephrine infusion and cerebrovascular carbon dioxide reactivity

In this study, we examined whether cerebrovascular carbon dioxide (CO(2)) reactivity was related to the response of jugular venous oxygen saturation (SjvO(2)) to phenylephrine infusion in diabetic patients during cardiopulmonary bypass. Forty diabetic patients scheduled for coronary artery bypass graft surgery were studied, and 40 age-matched nondiabetic cardiopulmonary bypass patients served as controls. Cerebrovascular CO(2) reactivity was measured continuously using transcranial Doppler. Mean arterial blood pressure (MAP) was increased by repeated phenylephrine infusion until reaching 100% of baseline values. There was a significant difference in absolute CO(2) reactivity between the diabetic and control groups (controls, 2.8 +/- 0.7 cm. s(-1). mm Hg(-1); diabetics, 2.2 +/- 1.1 cm. s(-1). mm Hg(-1); P = 0.02). Among the diabetics, absolute CO(2) reactivity in insulin-dependent patients was less than that in noninsulin-dependent patients (diet therapy group, 3.2 +/- 0.7; glibenclamide group, 2.6 +/- 0.7; insulin-dependent group, 1.0 +/- 0.7; P < 0.01). There was a correlation between absolute CO(2) reactivity and the mean slope of SjvO(2) versus MAP for increasing MAP (r = 0.54; P < 0.0001). In conclusion, we found that the interrelationship between SjvO(2) responsiveness to phenylephrine infusion and cerebrovascular CO(2) reactivity, as well as impaired cerebrovascular autoregulation, were associated with previous hyperglycemia.

Gender influence on cognitive function after cardiac operation

BACKGROUND

Women are at higher risk than men for stroke after cardiac operation. The purpose of this study was to evaluate for gender influences on the more common postoperative neurologic complication, cognitive dysfunction.

METHODS

A standard battery of neuropsychological tests was administered to 117 patients (79 men and 38 women) the day before and again 4 to 6 weeks after cardiac operation. The battery assessed a broad array of cognitive domains, including attention, memory, executive function, and psychomotor processing speed. Analysis was performed only on patients with data from both testing sessions. Data were analyzed to assess for a dichotomous definition of postoperative cognitive impairment and to evaluate for factors influencing test results for specific cognitive domains.

RESULTS

The frequency of one standard deviation decline on two or more cognitive tests compared with preoperative results (women, 10.7 % versus men, 9.9 %; p = 0.527), no decline, or one standard deviation improvement on each test postoperatively was no different between genders. After adjusting for age, gender, preexisting medical conditions, level of attained education, preoperative cognitive tests results, type of operation, and duration of cardiopulmonary bypass, female gender was independently associated with poorer performance postoperatively on visuospatial tasks. Other variables significantly related to postoperative cognitive function varied among the specific cognitive domains.

CONCLUSIONS

These data suggest that, although the frequency of cognitive dysfunction after cardiac operation is similar for women and men, women appear more likely to suffer injury to brain areas subserving visuospatial processing. Risk factors for postoperative cognitive impairment vary depending on cognitive domain, suggesting multiple etiologies for this form of perioperative neurologic injury.

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.

Increasing mean arterial blood pressure has no effect on jugular venous oxygen saturation in insulin-dependent patients during tepid cardiopulmonary bypass

Preexisting diabetes mellitus is one of the major factors related to adverse postoperative neurological disorders after cardiac surgery. In previous reports, we found that diabetic patients more often experienced cerebral desaturation than nondiabetic patients during normothermic cardiopulmonary bypass (CPB). The purpose of this study was to examine the effects of increasing mean arterial blood pressure (MAP) by the administration of phenylephrine on internal jugular venous oxygen hemoglobin saturation (SjvO2) during tepid CPB in diabetic patients. We studied 20 diabetic patients scheduled for elective coronary artery bypass graft surgery and, as a control, 20 age-matched nondiabetic patients. 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, MAP was increased by the repeated administration of a 10-microg bolus of phenylephrine until it reached 100% of baseline values. There was a significant difference in SjvO2 value between the Diabetic and CONTROL GROUPs after the administration of phenylephrine (Diabetic group, 56% +/- 6%;

CONTROL GROUP

60% +/- 4%) (P < 0.05). There was a significant difference in the arterial-jugular oxygen content difference value between the Diabetic and CONTROL GROUPs after the administration of phenylephrine (diabetic group, 4.9% +/- 0.6%; CONTROL GROUP, 4.5% +/- 0.4%) (P < 0.05). We subdivided the Diabetic group into three groups (Diet Therapy group [n = 4], Glibenclamide group [n = 10], and Insulin-Dependent group [n = 6]). There was a significant difference in the mean slopes of SjvO2 versus cerebral perfusion pressure for increasing cerebral perfusion pressure between the Insulin-Dependent group and the other groups (Dunnett test: P = 0.04). Increasing MAP had no effects on the SjvO2 value in insulin-dependent patients during tepid CPB.

IMPLICATIONS

We examined the effects of increasing mean arterial blood pressure (MAP) by the administration of phenylephrine on internal jugular venous oxygen saturation (SjvO2) during tepid cardiopulmonary bypass in diabetic patients and found that increasing MAP had no effect on the SjvO2 value in insulin-dependent patients.

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.