Neurologic assessment and cardiac surgery

Timing of Recognition for Perioperative Strokes Following Cardiac Surgery

INTRODUCTION

More than half of reported perioperative strokes following cardiac surgery are identified beyond postoperative day one. The objective of our study was to determine preoperative and intraoperative factors that are associated with stroke following cardiac surgery and to identify factors that may contribute delayed recognition of perioperative stroke.

METHODS

Patients undergoing coronary artery bypass surgery or isolated valve surgery from January 2, 2015 to April 28, 2017 at an academic health system were identified from the Society of Thoracic Surgeons Registry. We determined preoperative and intraoperative factors associated with perioperative stroke. Two neurologists performed retrospective chart reviews on perioperative stroke patients to determine the last seen well time and the stroke cause.

RESULTS

During the study period, 2795 patients underwent coronary artery bypass surgery or isolated valve surgery (mean age 64 ± 11 years, 71% male, 72% Caucasian, 9% history of stroke), of which 43 (1.5%) had a perioperative stroke; 31 (72%) patients had an embolic mechanism of stroke based on neuroimaging. In multivariable analysis, perioperative strokes were independently associated with increasing age (OR 1.04, 95% 1.01-1.07), history of stroke (OR 2.73, 95% CI 1.47-5.06), and history of thoracic aorta disease (OR 3.36, 95% CI 1.16-9.71). Strokes were identified after postoperative day one in 32 (74%) patients of which 26 (81%) had a preoperative last seen well time.

CONCLUSION

Given the high frequency of preoperative last seen well time in perioperative stroke patients who are identified after postoperative day one, delayed stroke recognition may contribute to the bimodal distribution in timing of perioperative stroke. Frequent neurological monitoring within 24 hours after CABG or isolated valve surgery should be considered for all patients undergoing cardiac surgery, particularly elderly patients and those with a history of stroke or thoracic aorta disease, to improve early stroke recognition.

Neutrophil-lymphocyte ratio as a predictor of cognitive dysfunction in carotid endarterectomy patients

BACKGROUND

Systemic inflammation has been implicated in the development of cognitive dysfunction following carotid endarterectomy (CEA). Neutrophil-lymphocyte ratio (NLR) is a reliable measure of systemic inflammation. We hypothesize that patients with elevated preoperative NLR have increased risk of cognitive dysfunction 1 day after CEA.

METHODS

Five hundred fifty-one patients scheduled for CEA were enrolled at Columbia University in New York, NY from 1995 to 2012. NLR was retrospectively reviewed; only 432 patients had preoperative NLR values available within 2 weeks of CEA. NLR was analyzed as a continuous variable and categorically with a cutoff of ≥5 and <5 and equal tertiles, as done in previous studies.

RESULTS

Patients with cognitive dysfunction had significantly higher NLR than those without cognitive dysfunction (4.5 ± 4.0 vs 3.2 ± 2.6; P < .001). The incidence of cognitive dysfunction was significantly higher in patients with NLR ≥5 than NLR <5 (34.7% vs 12.8%; P < .001). Significantly fewer patients in the low tertile had cognitive dysfunction than in the high tertile (6.9% vs 25.9%; P <.001) and middle tertile (6.9% vs 17.4%; P = .006). In the final multivariate model, diabetes mellitus (odds ratio [OR], 2.03; 95% confidence interval [CI], 1.08-3.75; P = .03) and NLR ≥5 (OR, 3.38; 95% CI, 1.81-6.27; P < .001) were significantly associated with higher odds of cognitive dysfunction, while statin use was significantly associated with lower odds (OR, 0.48; 95% CI, 0.27-0.84; P = .01).

CONCLUSIONS

Preoperative NLR is associated with cognitive dysfunction 1 day after CEA. NLR ≥5 and diabetes mellitus are significantly associated with increased odds of cognitive dysfunction whereas statin use is significantly associated with decreased odds.

Role of surgical factors in strokes after cardiac surgery

Deficient neurological disorders after heart surgery are destructive and affect vital prognosis. They concern between 3% to 9% of patients and are related mainly to embolic episodes or brain perfusion defects. The causes of these mechanisms are numerous, but surgical procedures and cardiopulmonary bypass optimization reduce their occurrence significantly.

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.

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.

Evaluation of neurologic assessment and outcomes in cardiac surgical patients

It is well recognized that cardiac surgery with cardiopulmonary bypass can potentially induce a wide spectrum of central nervous system (CNS) sequelae. Our awareness of the prevalence of these CNS complications is dependent on the validity of the available diagnostic methods. Current assessment methods designed to detect both focal and diffuse cerebral ischemia include neurologic examination, imaging techniques, biochemical markers, neuropsychologic assessment, and patient perceived outcomes. These techniques vary in their sensitivity and specificity, as well as feasibility for use in everyday clinical practice. There are currently only limited standardized methodologic guidelines for the assessment of CNS complications after cardiac surgery, which has resulted in considerable interstudy variability in the identification and reporting of outcomes. The application of clearly definable endpoints for reporting of CNS outcomes would be beneficial. The wealth of available data suggests that the incidence of overt CNS injury such as stroke has declined since the 1980s and is now approximately 2%, whereas evidence suggests that up to one third of cardiac surgery patients experience postoperative cognitive deficits. One of the clear strengths of the current era is the recognition of CNS injury associated with cardiac surgery, and the quest to improve our understanding of these outcomes. The application of more uniform assessment and reporting practices is surely vital to the continued advancement of cardiac surgery.

Neurophysiologic monitoring and outcomes in cardiovascular surgery

The first step to make in improving neurologic outcome is to recognize and accept neurologic injury occurs in all patient groups undergoing CPB. Fortunately, that stage has now been passed. Accurate detection and documentation of the incidence of brain injury is the next progression. At the same time, the cause of the injury needs to be established. Since the introduction of CPB, numerous improvements and refinements have been achieved, making it the acceptable, everyday clinical tool that has enabled the development of cardiac surgery. Despite these improvements, CPB-related morbidity persists. The advent of new technologic advances drives the quest for new techniques. New protective strategies for many end organs, including the heart, kidney, and brain, are evolving. No organ system should be viewed in isolation; otherwise, organ-specific protective strategies may arise in conflict. A strategy that confers absolute myocardial protection would be ideal, but at what cost to the protection of the kidneys, intestines, and brain? A neuroprotective strategy would ideally eliminate brain injury and be beneficial for all organs. The only way to continue to make progress is by the scientific evaluation of new techniques. The use of appropriate monitoring and outcome measures is fundamental to this process.

Neurobehavioural sequelae of cardiopulmonary bypass

The development of coronary artery bypass grafting (CABG) and its effect on angina is the product of a series of technical and scientific advances. Despite these advances, however, adverse neurobehavioural outcomes continue to occur. Stroke is the most serious complication of CABG, but studies that have identified demographic and medical risk factors available before surgery are an important advance. Short-term cognitive deficits are common after CABG, but may not be specific to this procedure. However, deficits in some cognitive areas such as visuoconstruction persist over time, and may reflect parieto-occipital watershed area injury secondary to hypoperfusion or embolic factors. Risk factors for cognitive decline may be time dependent, with short-term studies identifying factors that differ from those of long-term studies. Patients with depression before surgery are likely to have persistent depression afterwards. However, depression does not account for the cognitive decline after CABG. Since CABG is increasingly done in older patients with more comorbidity, the challenge is to identify patients at risk of adverse neurocognitive outcomes and to protect them by modification of the surgical procedure or by effective medical therapy.

Cerebral dysfunction after coronary artery bypass grafting done with mild or moderate hypothermia

OBJECTIVE

Ninety-nine patients undergoing elective coronary artery bypass grafting were enrolled in a prospective, randomized study to evaluate the incidence of cerebral dysfunction after "mild" or "moderate" hypothermia during cardiopulmonary bypass.

METHODS

Patients were evaluated before and after operation before hospital discharge and in some cases at follow-up at least 6 weeks later with a complete neurologic examination (85 patients) and a battery of standard neuropsychometric tests (86 patients).

RESULTS

Postoperative changes detected by neurologic examination consisted of the appearance of new primitive reflexes in both groups. No statistically significant differences in incidence were found. The neuropsychometric performances of the two groups were statistically similar by either event-rate or group-rate analysis.

CONCLUSIONS

There is no detectable difference in postoperative cerebral dysfunction in patients undergoing coronary artery bypass grafting who are supported by cardiopulmonary bypass with either mild or moderate hypothermia.