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Biomedical subjects

John M Murkin

Publications and source records attributed to John M Murkin.

At least 19 recordsLinked to original sources
PubMed2007

Monitoring brain oxygen saturation during coronary bypass surgery: a randomized, prospective study.

BACKGROUND: Cerebral deoxygenation is associated with various adverse systemic outcomes. We hypothesized, by using the brain as an index organ, that interventions to improve cerebral oxygenation would have systemic benefits in cardiac surgical patients. METHODS: Two-hundred coronary artery bypass patients were randomized to either intraoperative cerebral regional oxygen saturation (rSO2) monitoring with active display and treatment intervention protocol (intervention, n = 100), or underwent blinded rSO2 monitoring (control, n = 100). Predefined clinical outcomes were assessed by a blinded observer. RESULTS: Significantly more patients in the control group demonstrated prolonged cerebral desaturation (P = 0.014) and longer duration in the intensive care unit (P = 0.029) versus intervention patients. There was no difference in overall incidence of adverse complications, but significantly more control patients had major organ morbidity or mortality (death, ventilation >48 h, stroke, myocardial infarction, return for re-exploration) versus intervention group patients (P = 0.048). Patients experiencing major organ morbidity or mortality had lower baseline and mean rSO2, more cerebral desaturations and longer lengths of stay in the intensive care unit and postoperative hospitalization, than patients without such complications. There was a significant (r(2) = 0.29) inverse correlation between intraoperative rSO2 and duration of postoperative hospitalization in patients requiring > or =10 days postoperative length of stay. CONCLUSION: Monitoring cerebral rSO2 in coronary artery bypass patients avoids profound cerebral desaturation and is associated with significantly fewer incidences of major organ dysfunction.

Adult↗
PubMed2006

Neurologic complications in noncardiac surgery.

In this article, the incidence of nervous system injuries associated with noncardiac surgery is reviewed briefly. In general, these can be divided into injuries that are clinically apparent (eg, stroke or peripheral nerve damage), which may generally be detectable on clinical examination, and more subtle forms of brain injury (eg, personality changes and postoperative cognitive dysfunction), injuries that are primarily detected by neuropsychological testing.

Anesthesia↗
PubMed2006

Pathophysiological basis of CNS injury in cardiac surgical patients: detection and prevention.

The current understanding of adverse central nervous system (CNS) events following cardiac surgery involves several identifiable, evidence-based mechanisms: atherosclerotic emboli, microgaseous and microparticulate emboli, and hypoperfusion. Secondary factors, including patient co-morbidities and inherent genetic susceptibilities, as well as systemic inflammatory processes and a suboptimal metabolic milieu may interact to potentiate the extent of injury. In this review a number of these factors and their potential interactions will be explored with a view towards developing a comprehensive management strategy to minimize CNS injury.

Cardiopulmonary Bypass↗
PubMed2006

Full-dose aprotinin use in coronary artery bypass graft surgery: an analysis of perioperative pharmacotherapy and patient outcomes.

BACKGROUND: Inappropriate activation of hemostasis and inflammation may contribute to postoperative morbidity and mortality. The serine protease inhibitor, aprotinin, has been shown to prevent tissue and organ injury in laboratory and animal studies. In this retrospective analysis, we evaluated the relationship of aprotinin therapy with organ dysfunction in humans undergoing coronary artery bypass graft surgery (CABG). METHODS: Data from prospective randomized, double-blind, placebo-controlled studies evaluating the safety and efficacy of full-dose aprotinin (2 million KIU load, 2 million KIU pump prime, and 0.5 million KIU/h continuous infusion) to reduce blood loss and transfusion requirements in patients undergoing CABG (placebo, n = 861; aprotinin, n = 862) were examined retrospectively. Primary end-points were death, adverse cerebrovascular outcome, myocardial infarction (MI), and pharmacological interventions (inotropic drugs, vasopressors, and antiarrhythmics). RESULTS: Univariate analysis showed that relative to placebo, full-dose aprotinin therapy was associated with significant effects on the incidence of adverse cerebrovascular outcome (odds ratio [OR] 0.42, 95% confidence interval [CI] 0.19-0.93; P = 0.03) and use of inotropic drugs (OR 0.79, 95% CI 0.65-0.97; P = 0.02), vasopressors (OR 0.74, 95% CI 0.61-0.90; P < 0.01), and antiarrhythmics (OR 0.79, 95% CI 0.65-0.96; P = 0.02), but not death (OR = 1.00, 95% CI 0.54-1.85; P = 1.0) or MI (OR 0.92, 95% CI 0.64-1.31; P = 0.6). Multivariate analysis confirmed results of univariate analysis. CONCLUSIONS: This retrospective analysis of data collected from prospective, randomized, placebo-controlled studies in CABG shows that full-dose aprotinin use was associated with a lower risk of adverse cerebrovascular outcomes and a reduced need for use of vasoactive drugs; the risk of death and perioperative MI was not affected by aprotinin therapy.

Aged↗
PubMed2005

Comparing on-pump and off-pump coronary artery bypass grafting: numerous studies but few conclusions: a scientific statement from the American Heart Association council on cardiovascular surgery and anesthesia in collaboration with the interdisciplinary working group on quality of care and outcomes research.

One of the most hotly debated and polarizing issues in cardiac surgery has been whether coronary artery bypass grafting (CABG) without the use of cardiopulmonary bypass or cardioplegia (off-pump CABG, or OPCAB) is superior to that performed with the heart-lung machine and the heart's being chemically arrested (standard CABG). Various clinical trials are reviewed comparing the 2 surgical strategies, including several large retrospective analyses, meta-analyses, and the randomized trials that address different aspects of standard CABG and OPCAB. Although definitive conclusions about the relative merits of standard CABG and OPCAB are difficult to reach from these varied randomized and nonrandomized studies, several generalizations may be possible. Patients may achieve an excellent outcome with either type of procedure, and individuals' outcomes likely depend more on factors other than whether they underwent standard CABG or OPCAB. Nevertheless, there appear to be trends in most studies. These trends include less blood loss and need for transfusion after OPCAB, less myocardial enzyme release after OPCAB up to 24 hours, less early neurocognitive dysfunction after OPCAB, and less renal insufficiency after OPCAB. Fewer grafts tend to be performed with OPCAB than with standard CABG. Length of hospital stay, mortality rate, and long-term neurological function and cardiac outcome appear to be similar in the 2 groups. To definitively answer the remaining questions of whether either strategy is superior and in which patients, a large-scale prospective randomized trial is required.

American Heart Association↗
PubMed2005

Neurocognitive outcomes: the year in review.

PURPOSE OF REVIEW: This review is a survey of the recent literature investigating the etiology and the relative incidence of postoperative neurological and cognitive dysfunction after cardiac surgery. RECENT FINDINGS: Several studies reviewed here have employed transcranial Doppler for detection of cerebral emboli and compared results between patients undergoing beating-heart versus conventional cardiopulmonary bypass. A transcranial Doppler device ostensibly discriminating between particulate and gaseous emboli has additionally been employed, yet despite a consistently lower incidence of cerebral emboli associated with avoidance of cardiopulmonary bypass, several groups have reported similar incidences of cognitive dysfunction across these procedures, suggesting other, potentially more important, factors. Two recent studies have focused on the hazards associated with perioperative anemia in both infants and older patients, and which can result in developmental delay or profound changes in cerebral blood flow. A further study has identified an adverse interaction with postoperative hypoxia. The use of intraortic filtration for capture and removal of particulate macroemboli has been associated with a reduction in the incidence of clinically apparent central-nervous-system injury and should be further investigated. Several other studies identify pre-existing levels of central-nervous-system impairment prior to surgery, underscoring the confounding issues introduced by the failure to include a non-surgical comparator group. SUMMARY: While further evidence of cerebral embolization continues to accrue, several studies suggest that other factors may be of equal or greater importance in cognitive dysfunction. Further investigations into the role of perioperative anemia, co-incident hypoxemia and other aspects of perioperative care, e.g. hyperglycemia and postoperative hyperthermia, are warranted.

Journal Article↗
PubMed2005

Applied neuromonitoring in cardiac surgery: patient specific management.

Various studies have demonstrated that over 50% of patients presenting for coronary revascularization surgery have evidence of extracranial or intracranial atherosclerotic disease. Although evidence is compelling that cerebral emboli are a major cause of perioperative central nervous system (CNS) morbidity in such patients, it is also apparent that alterations in cerebral perfusion pressure and blood flow can profoundly influence the extent of injury after an embolic insult. In this context, the recent studies demonstrating improved CNS outcomes with applied neuromonitoring in cardiac surgical patients can be understood as reflecting the optimization of CNS perfusion characteristics with potential amelioration of microembolic injury. This review critically evaluates and discusses the relevant characteristics of applied neuromonitoring techniques, including bispectral index (BIS), transcranial Doppler (TCD), and near infrared reflectance spectroscopy (NIRS) in the context of patients undergoing cardiac surgical procedures. Recent outcomes data regarding CNS and related morbidity and the influence of neuromonitoring in these groups are evaluated.

Brain Chemistry↗
PubMed2005

Applied neuromonitoring and improving CNS outcomes.

Despite an overall decrease in perioperative morbidity and mortality, evidence of some degree of central nervous system dysfunction associated with coronary artery bypass graft (CABG) surgery-with or without cardiopulmonary bypass-has steadily mounted. From preoperative studies of CABG patients, it is apparent that over 50% of patients who present for cardiac surgery have evidence of either extracranial or intracranial atherosclerotic disease. Patient-specific factors thus have a fundamental impact on the risks of a brain injury developing after CABG surgery. Cerebral embolization and/or ischemic hypoperfusion are the most likely etiologic mechanisms for perioperative brain injury associated with cardiac surgery, and these factors are closely interrelated. Various monitoring techniques can decrease risk of intraoperative cerebral embolization and hypoperfusion and are associated with improved outcomes. Ultrasound guided aortic instrumentation (epiaortic scanning) can markedly decrease atheroembolic load and risk of stroke. Unrecognized sources of microgaseous emboli, including air entrainment from surgical purse string sutures and perfusionist interventions, can be identified and reduced by transcranial Doppler monitoring. Cerebral hypoperfusion from unrecognized cerebral venous obstruction, inadequate mean arterial pressure, or from hypocapnic cerebral alkalosis can be identified by multimodality neuromonitoring using regional cerebral oxygen saturation and transcranial Doppler. Overall patient outcomes can be improved, and hospital length of stay shortened, by applied neuromonitoring techniques.

Central Nervous System Diseases↗
PubMed2004

Perioperative detection of brain oxygenation and clinical outcomes in cardiac surgery.

Awareness of the high incidence of subtle central nervous system dysfunction after cardiopulmonary bypass, when it leads to increased vigilance in monitoring and diagnosis, remains the most important factor in the detection of postoperative injury. Preliminary data from an ongoing prospective study indicates that the use of noninvasive cerebral oximetry may be associated with a decreased length of stay in patients who have had coronary artery bypass grafting.

Brain↗
PubMed2004

Perioperative multimodality neuromonitoring: an overview.

Neurologic damage after cardiac surgery remains an important cause of postoperative morbidity. In addition to a wide variety of procedural risks, patient-specific factors such as the presence of extracranial or intracranial atherosclerotic disease, either alone or together, have a fundamental impact on the risk of brain injury developing after cardiovascular surgery. A variety of neurophysiologic monitoring techniques have been used during cardiovascular surgery in hopes of averting neurologic injury. In this issue of Seminars, the strengths and weaknesses of each are discussed by a group of highly experienced clinical investigators. The ultrasound techniques of epiaortic scanning and continuous transcranial Doppler insonation of large intracranial arteries can alter perfusion management and surgical habits to markedly decrease the delivery of atherosclerotic, lipoidal, and gaseous microemboli to the brain and other vital organs. Cerebral hypoperfusion from unrecognized cerebral venous obstruction, inadequate mean arterial pressure, or hypocapnic cerebral alkalosis can be identified by transcranial near-infrared spectroscopy, electroencephalogram, and sensory evoked potentials. Compromise of spinal cord perfusion during the repair of thoracoabdominal aneurysms may be identified and corrected with the guidance provided by transcranial electric motor-evoked potentials. Quantitative electroencephalogram and auditory evoked potential indices also appear beneficial in producing objective measures of the hypnotic component of anesthesia. These neuromonitoring methods, particularly when used in concert, can improve overall patient outcome and reduce hospital length of stay.

Brain↗
PubMed2004

The use of 3D epiaortic scanning to enhance evaluation of atherosclerotic plaque in the ascending aorta: a case series.

Transesophageal echocardiography (TEE) is becoming the standard of practice for cardiopulmonary bypass (CPB) surgery. Unfortunately, large sections of the ascending aorta are not visible on TEE, and epiaortic scanning has proven superior to TEE and aortic palpation in determining the extent of plaque in the ascending aorta. The recently introduced x4 3-dimensional (3D) ultrasound probe allows both real time 3D imaging and gated acquisition sequences. We present a case series in which 3D ultrasound was used for epiaortic imaging in patients undergoing elective cardiac surgery, and we discuss the benefits and limitations of this imaging modality.

Aged↗
PubMed2003

Inflammatory responses and CNS injury: implications, prophylaxis, and treatment.

EXCERPT: Early detection of perioperative stroke is essential if there is to be any opportunity to improve outcome. If there is suspicion of cerebral embolic stroke, scanning with computerized tomography can rule out acute hemorrhage and demonstrate diagnostic changes in a majority of patients within 5 hours of onset of symptoms. Strategies for reperfusion of ischemic tissue may include intraarterial thrombolysis in select patients with acute ischemic stroke even after recent cardiac operation. In one series, 13 patients with acute ischemic stroke within 12 days of cardiac operation underwent intraarterial thrombolysis within 6 hours of stroke symptom onset. Recanalization was complete in 1 patient and partial in 5, and 7 patients had low flow. Neurologic improvement occurred in 5 patients (38%). One patient needed a chest tube for hemothorax; 2 others received transfusions for low hemoglobin. No operative intervention for bleeding was necessary. In addition to thrombolysis, mechanical clot removal may be attempted. Thromboaspiration requires favorable anatomy and a fresh nonadhesive clot. It reduces the time for recanalization, has no hemorrhagic risk, and may prevent distal clot migration. Thromboaspiration may be attempted as an adjunct or alternative to intraarterial fibrinolysis for basilar artery recanalization. If massive cerebral gas embolism is suspected and hyperbaric facilities are available, confirmation can be obtained by early single-photon emission tomography (SPET) and hyperbaric oxygen therapy instituted. This process was successfully undertaken in a case of paradoxical air embolism in a patient undergoing percutaneous nephrolithotripsy in the prone position and presenting with blindness and neurological deficits 8 hours later. Treatment with hyperbaric oxygen therapy was successful in this case.

Animals↗
PubMed2002

Hemodynamic changes during cardiac manipulation in off-CPB surgery: relevance in brain perfusion.

The recent introduction of various cardiac stabilization and positioning devices, alone or in combination with deep pericardial traction sutures, has greatly increased the ability to perform beating heart surgery to accomplish multi-vessel coronary revascularization without the need for cardiopulmonary bypass (CPB), with its associated risks. However, positioning the heart for anastomosis of the circumflex (Cx) and the posterior descending artery poses a risk of inducing hypotension, impaired cardiac output, and generalized hemodynamic instability with risk of cerebral compromise. This report discusses clinical studies suggesting that compromised right ventricular diastolic filling as a result of direct ventricular compression, rather than impaired contractility or ischemia, may be the primary mechanism for producing hemodynamic instability during OPCAB surgery. Foremost among measures to minimize ventricular compression is optimal placement of the myocardial stabilization device. Secondary measures include steep Trendelenburg positioning, fluid loading, right-sided pleuro-pericardial window that allows rotation of the heart by partial herniation into the right pleural cavity, and possibly certain pharmacological agents. This report also analyzes the effect that variable degrees of hemodynamic disturbance accompanying displacement of the heart for OPCAB surgery has on endorgan perfusion and considers the effects of hypotensive agents, direct cerebral dilators, and patient-specific factors on cerebral blood flow. The role of the partial aortic occlusion clamp and risk of stroke is also considered. We conclude that for cardiac surgery patients considered at increased risk of adverse central nervous system events, direct monitoring of cerebral function and avoidance of aortic manipulation is strongly recommended.

Brain↗