Anesthesiologists
24 years of experience
Video profile
Accepting new patients
University City
3400 Spruce St
Philadelphia, PA 19175
215-662-7500
Locations and availability (4)

Education ?

Medical School Score Rankings
University of Pennsylvania (1986)
  • Currently 4 of 4 apples
Top 25%

Awards & Distinctions ?

Appointments
University of Pennsylvania
Assistant Professor of Anesthesiology and Critical Care
Associations
American Board of Anesthesiology

Affiliations ?

Dr. Floyd is affiliated with 8 hospitals.

Hospital Affilations

Score

Rankings

  • Hospital of the University of PA
    3400 Spruce St, Philadelphia, PA 19104
    • Currently 4 of 4 crosses
    Top 25%
  • Stony Brook University Hospital
    100 Nicolls Rd, Stony Brook, NY 11794
    • Currently 4 of 4 crosses
    Top 25%
  • Pennsylvania Hospital University PA Health System
    800 Spruce St, Philadelphia, PA 19107
    • Currently 4 of 4 crosses
    Top 25%
  • University of PA Medical Center/Presbyterian
    51 N 39th St, Philadelphia, PA 19104
    • Currently 3 of 4 crosses
    Top 50%
  • Clinical Practices of the University of Pennsylvania
  • Pennsylvania Hospital
  • Presbyterian Medical Center Of The University Of Pennsylvania Health System
  • University Hospital
  • Publications & Research

    Dr. Floyd has contributed to 28 publications.
    Title An Organized, Comprehensive, and Security-enabled Strategic Response to the Haiti Earthquake: a Description of Pre-deployment Readiness Preparation and Preliminary Experience from an Academic Anesthesiology Department with No Preexisting International Disaster Response Program.
    Date January 2011
    Journal Anesthesia and Analgesia
    Excerpt

    On Tuesday, January 12, 2010 at 16:53 local time, a magnitude 7.0 M(w) earthquake struck Haiti. The global humanitarian attempt to respond was swift, but poor infrastructure and emergency preparedness limited many efforts. Rapid, successful deployment of emergency medical care teams was accomplished by organizations with experience in mass disaster casualty response. Well-intentioned, but unprepared, medical teams also responded. In this report, we describe the preparation and planning process used at an academic university department of anesthesiology with no preexisting international disaster response program, after a call from an American-based nongovernmental organization operating in Haiti requested medical support. The focus of this article is the pre-deployment readiness process, and is not a post-deployment report describing the medical care provided in Haiti.

    Title Sex, Aging, and Preexisting Cerebral Ischemic Disease in Patients with Aortic Stenosis.
    Date October 2010
    Journal The Annals of Thoracic Surgery
    Excerpt

    Patients undergoing cardiac surgery have a high frequency of preexisting cerebral ischemic lesions, the presence of which appears to predict cognitive sequelae. Patients undergoing aortic valve replacement for aortic stenosis (AS) incur an exceptionally high risk for perioperative cerebral ischemia. The extreme risk in this subgroup may arise from the preexisting burden of cerebral ischemic disease. We tested the hypotheses that increasing age, female sex, coronary artery disease, and the severity of AS are predictive of the severity of preexisting cerebral ischemic lesions.

    Title Acute Anemia Elicits Cognitive Dysfunction and Evidence of Cerebral Cellular Hypoxia in Older Rats with Systemic Hypertension.
    Date October 2010
    Journal Anesthesiology
    Excerpt

    Postoperative cognitive dysfunction occurs frequently after cardiac, major vascular, and major orthopedic surgery. Aging and hypertensive cerebrovascular disease are leading risk factors for this disorder. Acute anemia, common to major surgery, has been identified as a possible contributor to postoperative cognitive dysfunction. The effect of hypoxia upon cognition and the cellular and molecular processes involved in learning and memory has been well described. Cerebrovascular changes related to chronic hypertension may expose cells to increased hypoxia with anemia.

    Title Evaluation of Cuff-induced Ischemia in the Lower Extremity by Magnetic Resonance Oximetry.
    Date March 2010
    Journal Journal of the American College of Cardiology
    Excerpt

    The aim of this study was to evaluate vascular function in the lower extremities by making direct time-course measurement of oxygen saturation in the femoral/popliteal arteries and veins during cuff-induced reactive hyperemia with magnetic resonance imaging-based oximetry.

    Title Con: Tight Perioperative Glycemic Control.
    Date February 2010
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Title Detection of Lactate with a Hadamard Slice Selected, Selective Multiple Quantum Coherence, Chemical Shift Imaging Sequence (hdmd-selmqc-csi) on a Clinical Mri Scanner: Application to Tumors and Muscle Ischemia.
    Date February 2010
    Journal Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine
    Excerpt

    Lactate is an important metabolite in normal and malignant tissues detectable by NMR spectroscopy; however, it has been difficult to clinically detect the lactate methyl resonance because it is obscured by lipid resonances. The selective homonuclear multiple quantum coherence transfer technique offers a method for distinguishing lipid and lactate resonances. We implemented a three-dimensional selective homonuclear multiple quantum coherence transfer version with Hadamard slice selection and two-dimensional phase encoding (Hadamard encoded-selective homonuclear multiple quantum coherence transfer-chemical shift imaging) on a conventional clinical MR scanner. Hadamard slice selection is explained and demonstrated in vivo. This is followed by 1-cm(3) resolution lactate imaging with detection to 5-mM concentration in 20 min on a 3-T clinical scanner. An analysis of QSel gradient duration and amplitude effects on lactate and lipid signal is presented. To demonstrate clinical feasibility, a 5-min lactate scan of a patient with a non-Hodgkin's lymphoma in the superficial thigh is reported. The elevated lactate signal coincides with the T(2)-weighted image of this tumor. As a test of selective homonuclear multiple quantum coherence transfer sensitivity, a thigh tourniquet was applied to a normal volunteer and an increase in lactate was detected immediately after tourniquet flow constriction. In conclusion, the Hadamard encoded-selective homonuclear multiple quantum coherence transfer-chemical shift imaging sequence is demonstrated on a phantom and in two lipid-rich, clinically relevant, in vivo conditions.

    Title Accuracy and Precision of Mr Blood Oximetry Based on the Long Paramagnetic Cylinder Approximation of Large Vessels.
    Date October 2009
    Journal Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine
    Excerpt

    An accurate noninvasive method to measure the hemoglobin oxygen saturation (%HbO(2)) of deep-lying vessels without catheterization would have many clinical applications. Quantitative MRI may be the only imaging modality that can address this difficult and important problem. MR susceptometry-based oximetry for measuring blood oxygen saturation in large vessels models the vessel as a long paramagnetic cylinder immersed in an external field. The intravascular magnetic susceptibility relative to surrounding muscle tissue is a function of oxygenated hemoglobin (HbO(2)) and can be quantified with a field-mapping pulse sequence. In this work, the method's accuracy and precision was investigated theoretically on the basis of an analytical expression for the arbitrarily oriented cylinder, as well as experimentally in phantoms and in vivo in the femoral artery and vein at 3T field strength. Errors resulting from vessel tilt, noncircularity of vessel cross-section, and induced magnetic field gradients were evaluated and methods for correction were designed and implemented. Hemoglobin saturation was measured at successive vessel segments, differing in geometry, such as eccentricity and vessel tilt, but constant blood oxygen saturation levels, as a means to evaluate measurement consistency. The average standard error and coefficient of variation of measurements in phantoms were <2% with tilt correction alone, in agreement with theory, suggesting that high accuracy and reproducibility can be achieved while ignoring noncircularity for tilt angles up to about 30 degrees . In vivo, repeated measurements of %HbO(2) in the femoral vessels yielded a coefficient of variation of less than 5%. In conclusion, the data suggest that %HbO(2) can be measured reproducibly in vivo in large vessels of the peripheral circulation on the basis of the paramagnetic cylinder approximation of the incremental field.

    Title Skeletal Muscle Microvascular Flow in Progressive Peripheral Artery Disease: Assessment with Continuous Arterial Spin-labeling Perfusion Magnetic Resonance Imaging.
    Date July 2009
    Journal Journal of the American College of Cardiology
    Excerpt

    We present the novel application of continuous arterial spin-labeling (CASL) magnetic resonance imaging (MRI) for the measurement of calf muscle perfusion in subjects with progressive peripheral arterial disease (PAD).

    Title Retrospective Correction for Induced Magnetic Field Inhomogeneity in Measurements of Large-vessel Hemoglobin Oxygen Saturation by Mr Susceptometry.
    Date June 2009
    Journal Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine
    Excerpt

    MR susceptometry-based blood oximetry relies on phase mapping to measure the difference in magnetic susceptibility between intravascular blood and surrounding tissue. The main source of error in MR susceptometry is the static field inhomogeneity caused by an interface between air and tissue or between adjacent tissue types. High-pass filtering has previously been used in conjunction with shimming to reduce the effect of low spatial-frequency modulations of the phase caused by large-scale induced magnetic fields. We demonstrate that high-pass filtering is not optimum for MR susceptometry because the results are sensitive to filter size. We propose an alternative method that acquires data without scanner-implemented default shimming, and fits, after appropriate weighting and masking, the static field inhomogeneity to a second-order polynomial. Compared to shimming the retrospective correction technique improved agreement between hemoglobin saturations measured in different segments of a vessel (femoral versus popliteal artery and vein) from three standard errors to less than one.

    Title Transit Delay and Flow Quantification in Muscle with Continuous Arterial Spin Labeling Perfusion-mri.
    Date September 2008
    Journal Journal of Magnetic Resonance Imaging : Jmri
    Excerpt

    PURPOSE: To test the hypothesis that flow measurements using continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI) in muscle depend upon transit delay, and examine the repeatability of CASL measurements. MATERIALS AND METHODS: A total of 23 healthy subjects underwent CASL imaging of the calf, foot, and forearm with varying postlabeling delay (PLD = 1000, 1500, and 1900 msec). Experiments were conducted on a 3.0T system. An orthopedic tourniquet system was employed to create a five-minute period of ischemia followed by a transient hyperemic flow. Imaging commenced two minutes prior to cuff inflation and ended three minutes after cuff release. RESULTS: CASL was found able to well resolve the time course of the hyperemic flow pattern with an effective TR of 16 seconds, although we were unable to establish that a plateau had been reached in the flow measurements even at a PLD as long as 1900 msec. Peak hyperemic flow measurements compared favorably with those obtained with contrast-enhanced (CE) MRI following a similar period of ischemia. Region-of-interest (ROI)-based repeated measurements varied by approximately 20% over a period of one hour. CONCLUSION: In all anatomic regions studied, flow measurements were found to increase with PLD, suggesting the prolonged transit delay in muscle.

    Title Hyperemic Flow Heterogeneity Within the Calf, Foot, and Forearm Measured with Continuous Arterial Spin Labeling Mri.
    Date June 2008
    Journal American Journal of Physiology. Heart and Circulatory Physiology
    Excerpt

    Arterial spin labeling (ASL) is a noninvasive magnetic resonance imaging (MRI) technique for microvascular blood flow measurement. We used a continuous ASL scheme (CASL) to investigate the hyperemic flow difference between major muscle groups in human extremities. Twenty-four healthy subjects with no evidence of vascular disease were recruited. MRI was conducted on a 3.0 Tesla Siemens Trio whole body system with a transmit/receive knee coil. A nonmagnetic orthopedic tourniquet system was used to create a 5-min period of ischemia followed by a period of hyperemic flow (occlusion pressure = 250 mmHg). CASL imaging, lasting from 2 min before cuff inflation to 3 min after cuff deflation, was performed on the midcalf, midfoot, and midforearm in separate sessions from which blood flow was quantified with an effective temporal resolution of 16 s. When muscles in the same anatomic location were compared, hyperemic flow was found to be significantly higher in the compartments containing muscles known to have relatively higher slow-twitch type I fiber compositions, such as the soleus muscle in the calf and the extensors in the forearm. In the foot, the plantar flexors exhibited a slightly delayed hyperemic response relative to that of the dorsal compartment, but no between-group flow difference was observed. These results demonstrate that CASL is sensitive to flow heterogeneity between diverse muscle groups and that nonuniform hyperemic flow patterns following an ischemic paradigm correlate with relative fiber-type predominance.

    Title Clinically Silent Cerebral Ischemic Events After Cardiac Surgery: Their Incidence, Regional Vascular Occurrence, and Procedural Dependence.
    Date September 2007
    Journal The Annals of Thoracic Surgery
    Excerpt

    BACKGROUND: The reported frequency of stroke after coronary artery bypass grafting varies between 1.5% and 6%, approaches 10% after aortic valve replacement, and may occur in between 40 to 70% in high-risk groups. Clinically silent infarction may be far more frequent and could contribute to long-term cognitive dysfunction in patients after cardiac procedures. Using diffusion-weighted magnetic resonance imaging we document the occurrence, vascular distribution, and procedural dependence of silent infarction after cardiac surgery with cardiopulmonary bypass. We also document the association of preexisting white matter lesions with new postoperative ischemic lesions. METHODS: Thirty-four patients underwent T2-weighted fluid attenuated inversion recovery and diffusion-weighted magnetic resonance imaging before and after cardiac surgery with cardiopulmonary bypass for coronary artery bypass grafting, aortic valve replacement, and mitral valve repair or replacement surgery. Images were evaluated by experienced neuroradiologists for number, size, and vascular distribution of lesions. RESULTS: Mean age of participants was 67 +/- 15 years. Imaging occurred before and 6 +/- 2 days after surgery. New cerebral infarctions were evident in 6 of 34 patients (18%), were often multiple, and in 67% of patients were clinically silent. The occurrence of new infarctions by surgical procedure was as follows: aortic valve replacement (2 of 6), coronary artery bypass grafting and aortic valve replacement (3 of 8), aortic valve replacement with root replacement (1 of 1), coronary artery bypass grafting and mitral valve repair or replacement (0 of 4), mitral valve repair or replacement (0 of 2), and isolated coronary artery bypass grafting (0 of 13). New infarction occurred in 6 of 15 (40%) of all procedures involving aortic valve replacement. The severity of preexisting white matter lesions trended toward predicting the occurrence of new lesions (p = 0.055). CONCLUSIONS: Diffusion-weighted imaging reveals new cerebral infarctions in nearly 40% of patients after aortic valve replacement.

    Title Integrity of the Cerebral Blood-flow Response to Hyperoxia After Cardiopulmonary Bypass.
    Date July 2007
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Excerpt

    OBJECTIVE: In this study, the hypothesis that cardiopulmonary bypass (CPB) alters the cerebral blood flow (CBF) vasoconstrictive response to hyperoxia was tested. DESIGN: A prospective, observational study was conducted. SETTING: The study was conducted at a single university hospital. PARTICIPANTS: Subjects were patients who presented for cardiac surgery with CPB. INTERVENTIONS: CBF was measured before and after CPB in 12 subjects while breathing 21% O(2) and 100% O(2). CBF was measured by using continuous arterial spin labeling (CASL) perfusion magnetic resonance imaging. Arterial pO(2) (mmHg), pCO(2) (mmHg), hemoglobin (Hgb), and oxygen content (CaO(2)) were also measured. MEASUREMENTS AND MAIN RESULTS: Mean age of the 12 subjects was 63 +/- 16 years. Hgb decreased from 12.0 (+/-2.4) g/dL to 9.2 (+/-2.9) g/dL postoperatively (p = 0.008). CBF increased by 39%, from 37.2 (+/-10.8) mL/100 g/min to 49.2 (+/-14.3)mL/100 g/min postoperatively (p = 0.01). In response to the hyperoxic challenge CBF decreased by 8.0 (+/-7.1) mL/100 g/min (21%) preoperatively and by 9.4 (+/-6.4) mL/100 g/min (19%) postoperatively (p = 0.58). By using multiple regression, the contribution of CPB to the hyperoxic CBF response (DeltaCBF) was evaluated, while controlling for other potentially important covariates known to influence CBF, including age, baseline CBF on 21% O(2), and changes in arterial pO(2), pCO(2), and CaO(2). CPB state was not found to be a significant covariate in controlling the CBF response to hyperoxia. CONCLUSIONS: CPB does not impair the CBF response to hyperoxia.

    Title Recurrence of Stroke After Cardiac Surgery: Insight into Pathogenesis Via Diffusion-weighted and Continuous Arterial Spin Labeling Perfusion Magnetic Resonance Imaging.
    Date April 2007
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Title Echocardiography in Suspected Acute Type a Aortic Dissection: Detection and Definitive Management of a False-positive Presentation.
    Date March 2007
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Title Aging: Impact Upon Local Cerebral Oxygenation and Blood Flow with Acute Isovolemic Hemodilution.
    Date May 2006
    Journal Journal of Neurosurgical Anesthesiology
    Excerpt

    Data from the neurosurgical critical care arena demonstrate a correlation between cerebral oxygenation, survival, and cognitive function. Transfusion may increase and hemodilution decrease cerebral oxygenation. Both acute and chronic anemia have been associated with cognitive dysfunction. Aggressive blood conservation protocols have been instituted across all age groups without conclusive evidence for their impact upon outcome. Aged subjects are at the greatest risk of cognitive sequelae after major surgery associated with significant blood loss. We hypothesize that cerebral physiologic changes associated with "normal" aging may compromise cerebral oxygenation in the presence of severe anemia.Fischer 344 rats, the NIH National Institute of Aging normal aging rat model, underwent a stepwise isovolemic hemodilution protocol. Age groups (Age Grp) studied were as follows: Age Grp-A (3 months), n=14; Age Grp-B (9 to 12 months), n=14; and Age Grp-C (24 months), n=14. Brain oxygen tension (PBrO2), laser Doppler flow, and mean arterial pressure were measured. Final hemoglobin averaged 6.1+/-0.9 g/dL. PBrO2 levels decreased from a baseline of 18.1+/-4.1 to 17.5+/-6.8 mm Hg (P=0.49), and laser Doppler flow increased by 18+/-20% (P<0.0001) after hemodilution. Employing repeated measures multiple regression, Age Grp (P=0.30) was not a significant controlling covariate of PBrO2 in response to isovolemic hemodilution. PBrO2 levels were actually higher in Age Grp-C animals at all time points of the hemodilution protocol, although this was not statistically significant. Aged animals were also fully capable of mounting a robust local cerebral hyperemic response to the anemic challenge that was not separable from the response of younger animals.

    Title Rapid and Rational Echocardiographic-assisted Management of Cardiogenic Shock After Coronary Artery Bypass Surgery.
    Date March 2006
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Title Major Clinical Outcomes in Adults Undergoing Thoracic Aortic Surgery Requiring Deep Hypothermic Circulatory Arrest: Quantification of Organ-based Perioperative Outcome and Detection of Opportunities for Perioperative Intervention.
    Date December 2005
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Excerpt

    OBJECTIVE: The purpose of this study was to describe clinical outcome after adult thoracic aortic surgery requiring standardized deep hypothermic circulatory arrest (DHCA), to determine mortality and length of stay, neurologic outcome, cardiorespiratory outcome, and hemostatic and renal outcome after DHCA. DESIGN: Retrospective and observational. SETTING: Cardiothoracic operating rooms and intensive care unit (ICU). PARTICIPANTS: All adults requiring thoracic aortic repair with DHCA. INTERVENTIONS: None. The study was observational. MAIN RESULTS: The cohort size was 110. All patients received an antifibrinolytic. The mortality rate was 8.2%. The mean length of stay was 6.8 days (ICU) and 14.0 days (hospital). The incidence of stroke was 8.1% and postoperative delirium was 10.9%. The rate of postoperative atrial fibrillation was 43.6%; 19.1% required postoperative mechanical ventilation longer than 72 hours. Chest tube drainage was 931 mL for the first 24 hours. Postoperative dialysis was required in 1.8% of patients. Renal dysfunction occurred in 40% to 50% of patients, depending on the definition. CONCLUSIONS: The protocol for DHCA at the authors' institution is associated with superior or equivalent perioperative outcomes to those reported in the literature. This study identified the need for further quantification of the clinical outcomes after DHCA in order to prioritize outcome-based hypothesis-driven prospective intervention in DHCA.

    Title Independent Cerebral Vasoconstrictive Effects of Hyperoxia and Accompanying Arterial Hypocapnia at 1 Ata.
    Date July 2004
    Journal Journal of Applied Physiology (bethesda, Md. : 1985)
    Excerpt

    Breathing 100% O2 at 1 atmosphere absolute (ATA) is known to be associated with a decrease in cerebral blood flow (CBF). It is also accompanied by a fall in arterial Pco2 leading to uncertainty as to whether the cerebral vasoconstriction is totally or only in part caused by arterial hypocapnia. We tested the hypothesis that the increase in arterial Po2 while O2 was breathed at 1.0 ATA decreases CBF independently of a concurrent fall in arterial Pco2. CBF was measured in seven healthy men aged 21-62 yr by using noninvasive continuous arterial spin-labeled-perfusion MRI. The tracer in this technique, magnetically labeled protons in blood, has a half-life of seconds, allowing repetitive measurements over short time frames without contamination. CBF and arterial blood gases were measured while breathing air, 100% O2, and 4 and 6% CO2 in air and O2 backgrounds. Arterial Po2 increased from 91.7 +/- 6.8 Torr in air to 576.7 +/- 18.9 Torr in O2. Arterial Pco2 fell from 43.3 +/- 1.8 Torr in air to 40.2 +/- 3.3 Torr in O2. CBF-arterial Pco2 response curves for the air and hyperoxic runs were nearly parallel and separated by a distance representing a 28.7-32.6% decrement in CBF. Regression analysis confirmed the independent cerebral vasoconstrictive effect of increased arterial Po2. The present results also demonstrate that the magnitude of this effect at 1.0 ATA is greater than previously measured.

    Title Precision of the Casl-perfusion Mri Technique for the Measurement of Cerebral Blood Flow in Whole Brain and Vascular Territories.
    Date March 2004
    Journal Journal of Magnetic Resonance Imaging : Jmri
    Excerpt

    PURPOSE: To analyze the precision of cerebral blood flow (CBF) measurements made with continuous arterial spin labeling(CASL) perfusion magnetic resonance imaging (MRI) over experimentally relevant intervals. MATERIALS AND METHODS: CASL perfusion MRI measurements of CBF on a 1.5-T GE Signa magnet were repeated in young healthy male and female subjects at one hour and one week. Precision of the measurement was evaluated at both time intervals. RESULTS: CASL perfusion MRI measurements of CBF yielded within-subject coefficients of variation (wsCV) of 5.8% for global and 13% for individual vascular regions when measurements were repeated within one hour. Differences in these values represent the error in post-processing. Global and regional CBF measurements over one week yielded wsCVs of 13% and 14%, respectively. At one week, error secondary to physiologic variability affected global and regional measurements to the same degree and masked the software post-processing error seen at one hour. The magnitude of the difference in repeated measures correlated with the magnitude of the measurement. CONCLUSION: CASL perfusion MRI CBF measurements are accurate and precise. Variability over longer periods of time appears attributable to physiologic factors. Repeatability of the CASL measurement is sensitive to the magnitude of the measurement. This should be taken into account when studies requiring repeated measures involve subjects with significant variability in CBF.

    Title Perioperative Changes in Cerebral Blood Flow After Cardiac Surgery: Influence of Anemia and Aging.
    Date January 2004
    Journal The Annals of Thoracic Surgery
    Excerpt

    BACKGROUND: Stroke occurs in 2% to 5% and cognitive dysfunction occurs acutely in 60% to 80% of patients early after cardiac surgery. Both may have long-term consequences. Research into mechanisms behind these sequelae has been focused intraoperatively, although there is little reason to believe that injury is limited to this period. Aging prominently increases the incidence of these sequelae. Anemia with cardiac surgery is acute and severe, should cause an increase in cerebral blood flow (CBF), and may impact stroke and cognitive function in this setting. To better understand changes in perioperative CBF physiology we have measured changes in CBF and the influence of anemia and aging on these changes. METHODS: Cerebral blood flow was measured using the noninvasive continuous arterial spin labeling perfusion magnetic resonance imaging method. Cerebral blood flow, mean arterial pressure, hemoglobin, hemoglobin oxygen saturation, and cardiopulmonary bypass time were recorded in 12 subjects before and 6 +/- 2 days after cardiac surgery. RESULTS: Cerebral blood flow increased from 44.6 +/- 15.6 mL100 g(-1)min(-1) to 64.4 +/- 20.1 mL100 g(-1)min(-1) after cardiac surgery, or 49.1% +/- 26.7%, (p < 0.0001). The absolute change in CBF (DeltaCBF) was predicted by the following regression model: DeltaCBF = -55 + 0.64(Age) + 0.53(CBF(Pre)) -3.3(DeltaHgb); R(2) = 0.81; p = 0.003, where CBF(Pre) is the baseline preoperative CBF and DeltaHgb is the change in hemoglobin from preoperative to postoperative periods. CONCLUSIONS: Cerebral blood flow increases after cardiac surgery, and anemia appears to be an important cause. Age appears also to be an important covariate, with advancing age further increasing the magnitude of this hyperemia. The interrelationship of aging and anemia, in determining perioperative changes in CBF, and potentially cerebral oxygenation, may have important implications for the understanding of perioperative stroke and cognitive dysfunction after cardiac surgery.

    Title Functional Mri and Its Applications to the Clinical Neurosciences.
    Date August 2001
    Journal The Neuroscientist : a Review Journal Bringing Neurobiology, Neurology and Psychiatry
    Excerpt

    Functional magnetic resonance imaging (fMRI) is an emerging methodology for studying regional brain function in vivo at relatively high spatial and temporal resolution. Because MRI methods are comparatively inexpensive and entirely noninvasive, fMRI has rapidly become one of the most popular approaches for brain mapping in cognitive and systems neuroscience. There has also been great interest in using fMRI to assist in clinical diagnosis and management, with promising demonstrations of feasibility in a number of applications. Both resting and task-specific regional brain activity can be measured, primarily utilizing alterations in regional cerebral blood flow (CBF) as a surrogate marker for neural function. This article reviews the biophysical and physiological bases of fMRI and its applications to the clinical neurosciences, with particular attention to potential challenges of fMRI under pathophysiological conditions. Carefully controlled prospective evaluation of clinical fMRI in its various potential applications will be required for fMRI to be validated as a clinically useful tool. Because the technology for fMRI is widely available, its impact could be substantial.

    Title Postoperative Neurologic Assessment and Management of the Cardiac Surgical Patient.
    Date January 2001
    Journal Seminars in Thoracic and Cardiovascular Surgery
    Excerpt

    The neurologic evaluation of patients in the immediate postoperative period and postanesthetic state is unique and challenging. Neurologic assessment is complicated by the lingering residual effects of anesthetics as well as by the effects of narcotic analgesics, anxiolytics, and muscle relaxants, especially in ventilated patients. In this review we examine the suspected causes, clinical manifestations, diagnostic options, and intervention schemes for the common neurologic syndromes seen after cardiac operations.

    Title Intestinal Ischemia: Treatment by Peritoneal Lavage with Oxygenated Perfluorochemical.
    Date April 1988
    Journal Journal of Pediatric Surgery
    Excerpt

    Though the delivery of elemental oxygen to tissues ravaged by anaerobic infection may be useful, little data exists that suggests that such therapy may benefit ischemic tissue. We report the development of a model to test the question that peritoneal lavage with an oxygen containing solution may favorably influence occlusive intestinal ischemia. Adult Sprague-Dawley rats with Nembutal (sodium pentobarbital) anesthesia underwent midline laparotomy; a microvascular clamp was applied to the superior mesenteric artery (SMA); and an inflow and outflow lavage catheter was placed. Treatment groups included control rats undergoing SMA occlusion only without lavage, rats lavaged with albumin during SMA occlusion (medium control), and rats lavaged during SMA occlusion with oxygenated perfluorochemical FC-47 emulsified in albumin (O2-FC-47). The increase in serum L-lactate following occlusion was used as an index of intestinal injury whether the perfusate was maintained at room temperature (28 degrees C) or body temperature (37 degrees C). Beginning with time O, which corresponded to the time of unclamping, subsequent samples were collected at 15, 30, and 60 minutes after a 30-minute SMA occlusion. Sequential lactates in 13 control rats were 4.18, 4.10, 3.88, and 4.52 mmol/L. Albumin lavaged animals had values at 28 degrees C of 2.23, 1.35, 1.8, and 2.44 mmol/L and values at 37 degrees C of 2.22, 1.40, 2.07, and 3.21 mmol/L, respectively. With O2-FC-47 lavage the respective lactates were 1.89, 1.09, 1.32, and 1.44 mmol/L at 28 degrees C and 2.14, 2.19, 2.50, and 2.1 mmol/L at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

    Title Oxygen-sensitive 19f Nmr Imaging of the Vascular System in Vivo.
    Date November 1987
    Journal Magnetic Resonance Imaging
    Excerpt

    The fluorine nuclear magnetic resonance spin-lattice relaxation rate (1/T1) of the perfluorochemical blood substitute perfluorotripropylamine (FTPA) is very sensitive to oxygen tension. This presents the possibility of measuring blood oxygen tension by 19F MR imaging. We obtained oxygen-sensitive 19F NMR images of the circulatory system of rats infused with emulsified FTPA. Blood oxygenation was assessed under conditions of both air- and 100% O2-breathing. T1 relaxation times were derived from MR images using a partial saturation pulse sequence. The T1 times were compared with a phantom calibration curve to calculate average blood pO2 values in the lung, liver, and spleen. The results showed marked, organ-specific increases in blood oxygen tension when the rat breathed 100% O2 instead of air.

    Title Morbidity and Mortality of Short-bowel Syndrome Acquired in Infancy: an Update.
    Date February 1985
    Journal Journal of Pediatric Surgery
    Excerpt

    The advent of total parenteral nutrition (TPN) has made survival beyond infancy possible for large numbers of patients who have sustained massive small intestinal loss due to a variety of intraabdominal catastrophes. However, the quantity and quality of life have been limited by the development of late sequelae due both to the protracted use of TPN and the long-term complications of foreshortening of the gut. To determine to what extent the morbidity and mortality of short-bowel syndrome (SBS) may have improved over the last 10 years, we reviewed our experience since 1973 with patients losing more than 50% of total small intestinal mass in infancy. The etiologies of SBS in the 16 study patients were necrotizing enterocolitis (6), midgut volvulus (5), multiple atresias (3), gastroschisis (1), and congenital SBS (1). Overall survival was 81%; total small intestinal length (SIL) at the time of diagnosis was 44.2 +/- 7.9 cm in survivors and 30.3 +/- 7.8 cm in nonsurvivors, probability values not significant. Although no patient survived without an ileocecal valve whose total SIL was greater than 20 cm, the three deaths in this series were not related directly to the SIL, but to end-stage liver disease resulting from TPN-associated cholestasis. Among the survivors, adaptation to enteral feedings required 13.8 +/- 2.5 mo, during which time weaning from TPN occurred; weight at adaptation was 6.87 +/- 1.32 kg.(ABSTRACT TRUNCATED AT 250 WORDS)

    Title Antiphospholipid Syndrome: Intraoperative and Postoperative Anticoagulation in Cardiac Surgery.
    Date
    Journal Journal of Cardiothoracic and Vascular Anesthesia
    Title Validation of Diffuse Correlation Spectroscopy for Muscle Blood Flow with Concurrent Arterial Spin Labeled Perfusion Mri.
    Date
    Journal Optics Express
    Excerpt

    Calf blood flow was measured simultaneously in healthy human subjects (n = 7) during cuff inflation and deflation using near-infrared diffuse correlation spectroscopy (DCS) and arterial spin labeled perfusion MRI (ASL-MRI). The DCS and ASL-MRI data exhibited highly correlated absolute and relative dynamic flow responses in each individual (p < 0.001). Peak flow variations during hyperemia were also significantly correlated, though more for relative (p = 0.003) than absolute (p = 0.016) flow. Repeated measurement variation was less than 8% for both modalities. The results provide much needed quantitative blood flow validation of the diffuse optical correlation method in humans.


    Similar doctors nearby

    Dr. Julie Drobish

    Anesthesiology
    Philadelphia, PA

    Dr. W Dunkman

    Anesthesiology
    Philadelphia, PA

    Dr. Nikhil Chawla

    Anesthesiology
    Philadelphia, PA

    Dr. Sy-Yeu Chern

    Anesthesiology
    Philadelphia, PA

    Dr. Rachel Dada

    Anesthesiology
    Philadelphia, PA

    Dr. Heather Graver

    Anesthesiology
    Philadelphia, PA
    Search All Similar Doctors