Use of the Reamer/Irrigator/Aspirator Decreases Carotid and Cranial Embolic Events in a Canine Model.

Background: Approximately 2 million patients in the United States annually undergo total joint arthroplasty with reaming and placement of intramedullary nails, resulting in extravasation of bone marrow and fat into the circulatory system and potentially causing fat embolism syndrome. Acute and chronic changes in mental status documented after these procedures may be related to embolic events. The Reamer/Irrigator/Aspirator (RIA) device has been shown to decrease intramedullary pressure during reaming.

Longitudinal evaluation of neurobehavioral outcomes after carotid revascularization.

Background: Carotid revascularization, including carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS), is performed for stroke risk reduction but may also impact cognitive function. Cognitive outcomes observed after carotid revascularization have been inconsistent, and mechanistic relationships with procedural factors are poorly understood. To further explore associations between carotid revascularization and cognitive outcomes, a prospective longitudinal evaluation was conducted of patients undergoing elective CEA or CAS for hemodynamically significant carotid stenosis.

Cannula design reduces particulate and gaseous emboli during cardiopulmonary bypass for coronary revascularization.

Purpose: The incidence of neurocognitive deficits after coronary bypass surgery remains problematic, with atheroembolism being one of the major causes. External manipulation of aorta and the "sandblasting" effect of the high-velocity perfusion jet can cause dislodgement of atheromatous debris.

Description: A new arterial cannula features a tip configuration that diffuses the flow through multiple outlets, providing reduced velocity and shear with one central and three diverted flow streams.

Consensus statement: minimal criteria for reporting the systemic inflammatory response to cardiopulmonary bypass.

The lack of established cause and effect between putative mediators of inflammation and adverse clinical outcomes has been responsible for many failed anti-inflammatory interventions in cardiopulmonary bypass (CPB). Candidate interventions that impress in preclinical trials by suppressing a given inflammation marker might fail at the clinical trial stage because the marker of interest is not linked causally to an adverse outcome. Alternatively, there exist examples in which pharmaceutical agents or other interventions improve clinical outcomes but for which we are uncertain of any antiinflammatory mechanism.

Consensus statement: Defining minimal criteria for reporting the systemic inflammatory response to cardiopulmonary bypass.

The causal factors of the systemic inflammatory response to cardiopulmonary bypass (CPB) were correctly identified in the early 1990 s: "...

Statistical significance versus clinical significance.

Unfortunately, the data were statistically nonsignificant due to insufficient power and poor experimental design. Conversely, many large clinical trials obtain a high level of statistical significance with miniscule differences between groups, which are completely clinically irrelevant. However, with proper marketing, billions can be made from results of dubious clinical importance.

Twenty years trying to protect the brain: what do we know?

Thirty-five years ago at the Nixon Watergate hearings, a young attorney named Fred Thompson, current US presidential candidate, asked "What did the President know and when did he know it?" A couple of word changes and this question would be appropriate to ask any number of surgical specialties regarding negative neurologic outcomes. Even today, some specialties are in denial about impaired brain function after surgical intervention. Fortunately, the cardiac surgery community has been in the forefront in efforts to protect the brain.

Deformable emboli and inflammation: temporary or permanent damage?

Neurologic sequelae after cardiopulmonary bypass have a multi-factorial etiology. Although it is typically thought that a neurologic dysfunction means a focal lesion, symptoms of a brain disorder can be initiated by metabolic disruption such as from hyper- or hypoglycemia, hypercalcemia, renal and hepatic injury, fatigue, and anesthesia. However, one of the most important causes of acute neurologic dysfunction is edema.

Cannulae and cell saver design: do they make a difference?

In the evolution of cardiopulmonary bypass (CPB), it is becoming increasing obvious that minimizing microembolization is critical in protecting the brain. Every component of the CPB circuit and ancillary apparatus must be evaluated and, if necessary, re-engineered with the reduction of microemboli a major focus. Cardiotomy suction has been identified as a major source of lipid microemboli.

Coronary artery bypass grafting with single cross-clamp results in fewer persistent neuropsychological deficits than multiple clamp or off-pump coronary artery bypass grafting.

Background: In coronary artery bypass grafting (CABG) patients, neuropsychological deficits that are present from the time of the operation through 6 months postoperatively are considered permanent and represent organic brain damage related to the operation. We hypothesized that changes in our surgical method would reduce persistent deficits.

Methods: From 1999 to 2004, consenting CABG patients were randomly assigned to multiple aortic cross-clamp or single aortic cross-clamp technique.

Preliminary report: functional MRI of the brain may be the ideal tool for evaluating neuropsychologic and sleep complaints of patients with primary hyperparathyroidism.

Background: The incidence, pattern, and severity of sleep disturbance and cognitive dysfunction has not been well characterized for patients with primary hyperparathyroidism (PHPT). There is no agreement on the mechanism of the development or resolution of such symptoms, and in no previous study has cerebral activity been functionally assessed and change documented following surgical cure of patients with PHPT.

Methods: We undertook a prospective analysis to obtain pilot data on 6 patients with PHPT.

Single crossclamp improves 6-month cognitive outcome in high-risk coronary bypass patients: the effect of reduced aortic manipulation.

Objective: We hypothesized that a strategy that reduced aortic manipulation would reduce the incidence of cognitive deficits in patients undergoing coronary artery bypass grafting compared with the "traditional" approach and that neurobehavioral outcomes with the reduced aortic manipulation strategy would approach those obtained with off-pump coronary artery bypass surgery.

Methods: Consenting high-risk patients (those with older age, diabetes, or hypertension) scheduled for coronary artery bypass grafting and cardiopulmonary bypass were randomly assigned to 1 of 2 aortic management protocols: (1) a traditional approach in which distal anastomoses were accomplished while the aorta was crossclamped but in which proximal anastomoses were sewn while a partial occlusion clamp was applied to the aorta (multiple aortic clamping group) or (2) a reduced aortic manipulation approach in which the aorta was clamped a single time with a reduced-pressure clamp (single aortic clamping group) and the partial occlusion clamp was not used. A contemporaneous group of patients undergoing off-pump coronary artery bypass surgery without cardiopulmonary bypass was also enrolled.

Issues in regulatory guidelines for data monitoring committees.

As clinical trials have emerged as the major research method for evaluating new interventions, the process for monitoring intervention safety and benefit has also evolved. The Data Monitoring Committee (DMC) has become the standard approach to implement this responsibility for many Phase III trials. Recent draft guidelines on the operation of DMCs by the Food and Drug Administration (FDA) have raised issues that need further clarification or discussion, especially for industry sponsored trials.

Liability issues for data monitoring committee members.

In randomized clinical trials, a data monitoring committee (DMC) is often appointed to review interim data to determine whether there is early convincing evidence of intervention benefit, lack of benefit or harm to study participants. Because DMCs bear serious responsibility for participant safety, their members may be legally liable for their actions. Despite more than three decades of experiences with DMCs, the issues of liability and indemnification have yet to receive appropriate attention from either government or industry sponsors.

Attempted control of hyperglycemia during cardiopulmonary bypass fails to improve neurologic or neurobehavioral outcomes in patients without diabetes mellitus undergoing coronary artery bypass grafting.

Objective: Hyperglycemia worsens outcomes in critical illness. This randomized, double-blind, placebo-controlled clinical trial tested whether insulin treatment of hyperglycemia during cardiopulmonary bypass would reduce neurologic, neuro-ophthalmologic, and neurobehavioral outcomes after coronary artery bypass grafting.

Methods: Three hundred eighty-one nondiabetic patients undergoing isolated coronary artery bypass grafting were given infusions of insulin or placebo when their blood glucose concentration exceeded 100 mg/dL during cardiopulmonary bypass.

Primary hyperparathyroidism, cognition, and health-related quality of life.

Objective: To provide a rigorous and critical review of studies in which formal neuropsychological (NP) testing and measurement of health-related quality of life (HRQL) were conducted pre- and post-parathyroidectomy for primary hyperparathyroidism (PHPT). These data contribute to the discussion on the utility of surgical intervention for nonclassic PHPT.

Summary Background Data: PHPT is a complex endocrinopathy involving calcium metabolism and a potent hormone made by the parathyroid glands.

Embolic factors associated with cardiac surgery.

Macro and microemboli can both cause significant neurologic dysfunction. The traditional belief in cardiac surgery was that the damage perpetrated by an embolus was caused by the occlusion of an arterial branch, resulting in an ischemic event and subsequent infarction. However, ongoing research has demonstrated that the mere passage of a deformable embolus (air, lipid, or semi-solid clot) will disrupt the endothelium as it is extruded through the vessel.

Noncardiac surgery brain injury: etiologic factors and prevention.

EXCERPT: During total joint arthroplasty, showers of bony spicules, marrow fat, and clot are carried by venous blood to the lungs, creating conditions not unlike those present in patients who have suffered traumatic long bone fractures. There is recent evidence that, like the fat embolism syndrome (FES), which often has a component of neurologic dysfunction, total joint arthroplasty and femoral nailing are associated with intraoperative brain embolization as determined by transcranial Doppler ultrasonography, and magnetic resonance brain imaging. Although there are good data demonstrating that intraoperative brain embolization occurs during total joint arthroplasties, the makeup and, even more importantly, the clinical significance of these emboli remain speculative.

Does vacuum-assisted venous drainage increase gaseous microemboli during cardiopulmonary bypass?

Background: Vacuum-assisted venous drainage enables adequate drainage through small-diameter cannulas but concerns are that it results in more gaseous microemboli delivered to the patient.

Methods: Five identical embolus detectors monitored the propagation of entrained air through a cardiopulmonary bypass (CPB) model. The ability of the CPB circuit to remove gaseous microemboli was studied with vacuum-assisted venous drainage and gravity siphon venous drainage using different pump speeds and rates of gaseous microemboli delivery.

Dexmedetomidine-induced sedation in volunteers decreases regional and global cerebral blood flow.

Unlabelled: Dexmedetomidine is a selective alpha(2)-agonist approved for sedation of critically ill patients. There is little information on the effects of dexmedetomidine on cerebral blood flow (CBF) or intracranial hemodynamics, despite considerable other pharmacodynamic data. We hypothesized that therapeutic doses of dexmedetomidine would decrease CBF.