Scholars@Duke
David Brett MacLeod

David Brett MacLeod

Associate Professor of Anesthesiology
Anesthesiology, Regional
david.macleod@duke.edu
Box 3094 Med Ctr, Durham, NC
2301 Erwin Road, 5695 HAFS Building, Durham, NC 27708

Selected Publications

Lactate accumulates in the cerebrospinal fluid after prolonged exercise.

Journal Article J Cereb Blood Flow Metab · December 7, 2025 The resting brain is fuelled by glucose with a small release of lactate. During exercise, the brain switches to extracting lactate from blood and this increases brain carbohydrate uptake in great excess to that of oxygen. The fate of this excess carbohydra ... Full text Link to item Cite

Brain glucose extraction is fixed at 10% despite twofold variability in resting cerebral blood flow in healthy humans.

Journal Article J Cereb Blood Flow Metab · December 7, 2025 In the resting, non-stimulated brain, metabolic demands are met exclusively by the delivery and extraction of glucose and oxygen at an ~6:1 ratio. Amongst healthy people at rest, there is marked variability in resting global cerebral blood flow (CBF) yet r ... Full text Link to item Cite

Cerebral oxygen extraction across different exercise intensities: Role of arterial P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_2}}}$.

Journal Article Exp Physiol · December 1, 2025 Stability in cerebral oxygen extraction fraction (OEF) is typically determined by alterations in cerebral blood flow (CBF). At rest, arterial partial pressure of carbon dioxide ( P aC O 2 ${P_{{\mathrm{aC}}{{\mathrm{O}}_2}}}$ ) and OEF exhibit a strong ... Full text Link to item Cite

Exercise and hypoxia independently stimulate platelet liberation of brain-derived neurotrophic factor and platelet factor 4.

Journal Article J Physiol · November 3, 2025 Brain-derived neurotrophic factor (BDNF) is an essential mediator of exercise-induced neuroplasticity. The majority of BDNF in circulation (∼99%) is stored bound to platelets. Platelet activation by exercise stimulates the release of their contents, repres ... Full text Link to item Cite

Preferential lactate metabolism in the human brain during exogenous and endogenous hyperlactataemia.

Journal Article J Physiol · November 2025 At rest, glucose serves as the brain's primary oxidative substrate; however, when circulating lactate is elevated, lactate oxidation increases. Whether this glucose-sparing effect differs when lactate is elevated via passive infusion versus exercise remain ... Full text Link to item Cite

Characterizing the physiology of circulatory arrest in humans.

Journal Article Nat Med · October 2025 The dying process from circulatory arrest is an underexplored domain in humans and has transdisciplinary pertinence. Here we conducted a prospective, observational cohort study of the dying process in 39 adults, with a multimodal assessment of cerebrovascu ... Full text Link to item Cite

Non-contact (touchless) monitoring of respiratory rate in a challenging anesthesia setting using a depth camera.

Journal Article J Clin Monit Comput · July 10, 2025 AIM: We have developed a non-contact ("touchless") system based on depth-sensing camera technology for continuous monitoring of respiratory activity. Previous work from our group has demonstrated high accuracy of the system in monitoring a wide range of re ... Full text Link to item Cite

Cerebrospinal fluid pH in chronic respiratory acidosis.

Journal Article J Appl Physiol (1985) · July 1, 2025 In this article, we extracted arterial and cerebrospinal fluid (CSF) acid-base data from 16 published articles concerning chronic respiratory acidosis. Using a traditional narrative review style literature search, we sought published research articles wher ... Full text Link to item Cite

Incidence of transient neurologic symptoms in patients receiving lidocaine spinal anesthesia for outpatient joint arthroplasty.

Journal Article Reg Anesth Pain Med · April 29, 2025 BACKGROUND: Spinal anesthesia is commonly administered for lower limb total joint arthroplasty, but the prolonged motor and sympathetic block associated with bupivacaine can delay recovery. In contrast, lidocaine, with its swift onset and intermediate dura ... Full text Link to item Cite

Cerebral Blood Flow in Orthostatic Intolerance.

Journal Article J Am Heart Assoc · February 4, 2025 Cerebral blood flow (CBF) is vital for delivering oxygen and nutrients to the brain. Many forms of orthostatic intolerance (OI) involve impaired regulation of CBF in the upright posture, which results in disabling symptoms that decrease quality of life. Be ... Full text Link to item Cite

Intense exercise at high altitude causes platelet loss across the brain in humans.

Journal Article J Physiol · November 2024 Platelets are known primarily for their role in blood clotting; however, it is becoming clear that they play diverse roles beyond that of haemostasis. Exercise has been shown to activate platelets and stimulate neurogenesis, neuroplasticity and improve cog ... Full text Link to item Cite

Severe hypoxaemic hypercapnia compounds cerebral oxidative-nitrosative stress during extreme apnoea: Implications for cerebral bioenergetic function.

Journal Article J Physiol · November 2024 We examined the extent to which apnoea-induced extremes of oxygen demand/carbon dioxide production impact redox regulation of cerebral bioenergetic function. Ten ultra-elite apnoeists (six men and four women) performed two maximal dry apnoeas preceded by n ... Full text Link to item Cite

Evidence for direct CO2 -mediated alterations in cerebral oxidative metabolism in humans.

Journal Article Acta Physiol (Oxf) · September 2024 AIM: How the cerebral metabolic rates of oxygen and glucose utilization (CMRO2 and CMRGlc, respectively) are affected by alterations in arterial PCO2 (PaCO2) is equivocal and therefore was the primary question of this study. METHODS: This retrospective ana ... Full text Link to item Cite

Feasibility of a Novel Augmented 6-Minute Incremental Step Test: A Simplified Cardiorespiratory Fitness Assessment Tool.

Journal Article JACC Adv · August 2024 BACKGROUND: The cardiopulmonary exercise test (CPET) is considered a gold standard in assessing cardiorespiratory fitness (CRF) but has limited accessibility due to competency requirements and cost. Incorporating portable sensor devices into a simple bedsi ... Full text Open Access Link to item Cite

Identifying Frailty Using Point-of-Care Ultrasonography: Image Acquisition and Assessment.

Journal Article J Vis Exp · July 26, 2024 Frailty is a significant predictor of a range of adverse outcomes in surgical patients, including increased mechanical ventilation time, longer hospital stays, unplanned readmissions, stroke, delirium, and death. However, accessible tools for screening in ... Full text Link to item Cite

Selected and shared hematological responses to apnea in elite human free divers and northern elephant seals (Mirounga angustirostris).

Journal Article Am J Physiol Regul Integr Comp Physiol · July 1, 2024 Despite elite human free divers achieving incredible feats in competitive free diving, there has yet to be a study that compares consummate divers, (i.e. northern elephant seals) to highly conditioned free divers (i.e., elite competitive free-diving humans ... Full text Link to item Cite

Shining a light on cerebral autoregulation: Are we anywhere near the truth?

Journal Article J Cereb Blood Flow Metab · June 2024 The near-infrared spectroscopy (NIRS)-derived cerebral oximetry index (COx) has become popularized for non-invasive neuromonitoring of cerebrovascular function in post-cardiac arrest patients with hypoxic-ischemic brain injury (HIBI). We provide commentary ... Full text Link to item Cite

Intravenous Ganaxolone: Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability in Healthy Adults.

Journal Article Clin Pharmacol Drug Dev · March 2024 Ganaxolone, a neuroactive steroid anticonvulsant that modulates both synaptic and extrasynaptic γ-aminobutyric acid type A (GABAA ) receptors, is in development for treatment of status epilepticus (SE) and rare epileptic disorders, and has been approved in ... Full text Link to item Cite

Prognostic significance of muscle fasciculations in critically Ill COVID-19 patients under mechanical ventilation

Journal Article Frontiers in Anesthesiology · January 1, 2024 Introduction: The COVID-19 pandemic brought unprecedented challenges to healthcare systems worldwide, particularly the often challenging physical recovery from critical illness. Among the myriad complications faced by these patients, ICU-acquired weakness ... Full text Cite

A novel ultrasound approach in assessing IMAT in critically ill patients

Journal Article Frontiers in Anesthesiology · January 1, 2024 Background: Muscle wasting is a common finding in critically ill patients associated with increased days of mechanical ventilation in the ICU. Muscle wasting and associated morphological changes are hallmarks of ICU-acquired weakness. Muscle wasting can be ... Full text Cite

Hemoglobin and cerebral hypoxic vasodilation in humans: Evidence for nitric oxide-dependent and S-nitrosothiol mediated signal transduction.

Journal Article J Cereb Blood Flow Metab · September 2023 Cerebral hypoxic vasodilation is poorly understood in humans, which undermines the development of therapeutics to optimize cerebral oxygen delivery. Across four investigations (total n = 195) we investigated the role of nitric oxide (NO) and hemoglobin-bas ... Full text Link to item Cite

Cerebral O2 and CO2 transport in isovolumic haemodilution: Compensation of cerebral delivery of O2 and maintenance of cerebrovascular reactivity to CO2.

Journal Article J Cereb Blood Flow Metab · January 2023 This study investigated the influence of acute reductions in arterial O2 content (CaO2) via isovolumic haemodilution on global cerebral blood flow (gCBF) and cerebrovascular CO2 reactivity (CVR) in 11 healthy males (age; 28 ± 7 years: body mass index; 23 ± ... Full text Link to item Cite

A pilot study to assess the feasibility of a remotely monitored high-intensity interval training program prior to allogeneic hematopoietic stem cell transplantation.

Journal Article PLoS One · 2023 INTRODUCTION: Although allogeneic hematopoietic stem cell transplantation (HCT) can be a curative therapy for hematologic disorders, it is associated with treatment-related complications and losses in cardiorespiratory fitness and physical function. High-i ... Full text Link to item Cite

Hypoxemia increases blood-brain barrier permeability during extreme apnea in humans.

Journal Article J Cereb Blood Flow Metab · June 2022 Voluntary asphyxia imposed by static apnea challenges blood-brain barrier (BBB) integrity in humans through transient extremes of hypertension, hypoxemia and hypercapnia. In the present study, ten ultra-elite breath-hold divers performed two maximal dry ap ... Full text Link to item Cite

Global REACH 2018: Characterizing Acid-Base Balance Over 21 Days at 4,300 m in Lowlanders.

Journal Article High Alt Med Biol · June 2022 Steele, Andrew R., Philip N. Ainslie, Rachel Stone, Kaitlyn Tymko, Courtney Tymko, Connor A. Howe, David MacLeod, James D. Anholm, Christopher Gasho, and Michael M. Tymko. Global REACH 2018: characterizing acid-base balance over 21 days at 4,300 m in lowla ... Full text Link to item Cite

Trans-cerebral HCO3- and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans.

Journal Article J Cereb Blood Flow Metab · April 2022 This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3-]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 ... Full text Link to item Cite

GLOBAL REACH 2018: intra-arterial vitamin C improves endothelial-dependent vasodilatory function in humans at high altitude.

Journal Article J Physiol · March 2022 High altitude-induced hypoxaemia is often associated with peripheral vascular dysfunction. However, the basic mechanism(s) underlying high-altitude vascular impairments remains unclear. This study tested the hypothesis that oxidative stress contributes to ... Full text Link to item Cite

Nitric oxide contributes to cerebrovascular shear-mediated dilatation but not steady-state cerebrovascular reactivity to carbon dioxide.

Journal Article J Physiol · March 2022 Cerebrovascular CO2 reactivity (CVR) is often considered a bioassay of cerebrovascular endothelial function. We recently introduced a test of cerebral shear-mediated dilatation (cSMD) that may better reflect endothelial function. We aimed to determine the ... Full text Link to item Cite

Acid-base balance at high altitude in lowlanders and indigenous highlanders.

Journal Article J Appl Physiol (1985) · February 1, 2022 High-altitude exposure results in a hyperventilatory-induced respiratory alkalosis followed by renal compensation (bicarbonaturia) to return arterial blood pH (pHa) toward sea-level values. However, acid-base balance has not been comprehensively examined i ... Full text Link to item Cite

Patient- and Ventilator-Specific Modeling to Drive the Use and Development of 3D Printed Devices for Rapid Ventilator Splitting During the COVID-19 Pandemic

Conference Lecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2022 In the early days of the COVID-19 pandemic, there was a pressing need for an expansion of the ventilator capacity in response to the COVID19 pandemic. Reserved for dire situations, ventilator splitting is complex, and has previously been limited to patient ... Full text Cite

Metabolic flexibility in patients undergoing Radical Cystectomy

Conference ANESTHESIA AND ANALGESIA · 2022 Cite

Prolonged progressive hypermetabolism during COVID-19 hospitalization undetected by common predictive energy equations.

Journal Article Clin Nutr ESPEN · October 2021 BACKGROUND & AIMS: Indirect calorimetry (IC) is the gold-standard for determining measured resting energy expenditure (mREE) in critical illness. When IC is not available, predicted resting energy expenditure (pREE) equations are commonly utilized, which o ... Full text Link to item Cite

The influence of hemoconcentration on hypoxic pulmonary vasoconstriction in acute, prolonged, and lifelong hypoxemia.

Journal Article Am J Physiol Heart Circ Physiol · October 1, 2021 Hemoconcentration can influence hypoxic pulmonary vasoconstriction (HPV) via increased frictional force and vasoactive signaling from erythrocytes, but whether the balance of these mechanism is modified by the duration of hypoxia remains to be determined. ... Full text Link to item Cite

Regulation of cerebral blood flow by arterial PCO2 independent of metabolic acidosis at 5050 m.

Journal Article J Physiol · July 2021 KEY POINTS: We investigated the influence of arterial PCO2 (PaCO2 ) with and without experimentally altered pH on cerebral blood flow (CBF) regulation at sea level and with acclimatization to 5050 m. At sea level and high altitude, we assessed stepwise alt ... Full text Link to item Cite

Influence of iron manipulation on hypoxic pulmonary vasoconstriction and pulmonary reactivity during ascent and acclimatization to 5050 m.

Journal Article J Physiol · March 2021 KEY POINTS: Iron acts as a cofactor in the stabilization of the hypoxic-inducible factor family, and plays an influential role in the modulation of hypoxic pulmonary vasoconstriction. It is uncertain whether iron regulation is altered in lowlanders during ... Full text Link to item Cite

The 2018 Global Research Expedition on Altitude Related Chronic Health (Global REACH) to Cerro de Pasco, Peru: an Experimental Overview.

Journal Article Exp Physiol · January 2021 NEW FINDINGS: What is the central question of this study? Herein, a methodological overview of our research team's (Global REACH) latest high altitude research expedition to Peru is provided. What is the main finding and its importance? The experimental ob ... Full text Link to item Cite

Implications for Neuromodulation Therapy to Control Inflammation and Related Organ Dysfunction in COVID-19.

Journal Article J Cardiovasc Transl Res · December 2020 COVID-19 is a syndrome that includes more than just isolated respiratory disease, as severe acute respiratory syndrome-coronavirus 2 (SARS-CoV2) also interacts with the cardiovascular, nervous, renal, and immune system at multiple levels, increasing morbid ... Full text Open Access Link to item Cite

Nitric oxide is fundamental to neurovascular coupling in humans.

Journal Article J Physiol · November 2020 KEY POINTS: Preclinical models have demonstrated that nitric oxide is a key component of neurovascular coupling; this has yet to be translated to humans. We conducted two separate protocols utilizing intravenous infusion of a nitric oxide synthase inhibito ... Full text Link to item Cite

Validation of a Noninvasive Assessment of Pulmonary Gas Exchange During Exercise in Hypoxia.

Journal Article Chest · October 2020 BACKGROUND: Pulmonary gas exchange efficiency, determined by the alveolar-to-arterial Po2 difference (A-aDo2), progressively worsens during exercise at sea-level; this response is further elevated during exercise in hypoxia. Traditionally, pulmonary gas ex ... Full text Link to item Cite

Acute reductions in haematocrit increase flow-mediated dilatation independent of resting nitric oxide bioavailability in humans.

Journal Article J Physiol · October 2020 Changes in haematocrit influence nitric oxide signalling through alterations in shear stress stimuli and haemoglobin scavenging of nitric oxide; these two regulatory factors have not been assessed simultaneously Isovolumic haemodilution led to a marked inc ... Full text Link to item Cite

Reply to Drs. Wang et al.

Journal Article J Appl Physiol (1985) · October 1, 2020 Full text Link to item Cite

A methodology to explore ventilatory chemosensitivity and opioid-induced respiratory depression risk.

Journal Article J Appl Physiol (1985) · September 1, 2020 Reported incidence of postoperative opioid-induced respiratory depression (OIRD) ranges from 0.5-41% and is not reliably predicted by traditional risk factors. This study tests a new methodology to investigate ventilatory chemosensitivity as a new potentia ... Full text Link to item Cite

Rapid Ventilator Splitting During COVID-19 Pandemic Using 3D Printed Devices and Numerical Modeling of 200 Million Patient Specific Air Flow Scenarios.

Journal Article Res Sq · August 12, 2020 There has been a pressing need for an expansion of the ventilator capacity in response to the recent COVID19 pandemic. To address this need, we present a system to enable rapid and efficacious splitting between two or more patients with varying lung compli ... Full text Link to item Cite

Perioperative Quality Initiative (POQI) consensus statement on fundamental concepts in perioperative fluid management: fluid responsiveness and venous capacitance.

Journal Article Perioper Med (Lond) · 2020 BACKGROUND: Optimal fluid therapy in the perioperative and critical care settings depends on understanding the underlying cardiovascular physiology and individualizing assessment of the dynamic patient state. METHODS: The Perioperative Quality Initiative ( ... Full text Open Access Link to item Cite

Assessment of a Non Invasive Brain Oximeter in Volunteers Undergoing Acute Hypoxia.

Journal Article Med Devices (Auckl) · 2020 INTRODUCTION: Research in traumatic brain injury suggests better patient outcomes when invasive oxygen monitoring is used to detect and correct episodes of brain hypoxia. Invasive brain oxygen monitoring is, however, not routinely used due to the risks, co ... Full text Link to item Cite

UBC-Nepal Expedition: Haemoconcentration underlies the reductions in cerebral blood flow observed during acclimatization to high altitude.

Journal Article Exp Physiol · December 2019 NEW FINDINGS: What is the central question of this study? The aim was to evaluate the degree to which increases in haematocrit alter cerebral blood flow and cerebral oxygen delivery during acclimatization to high altitude. What is the main finding and its ... Full text Link to item Cite

Global REACH 2018: High Blood Viscosity and Hemoglobin Concentration Contribute to Reduced Flow-Mediated Dilation in High-Altitude Excessive Erythrocytosis.

Journal Article Hypertension · June 2019 Excessive erythrocytosis (EE; hemoglobin concentration [Hb] ≥21 g/dL in adult males) is associated with increased cardiovascular risk in highlander Andeans. We sought to quantify shear stress and assess endothelial function via flow-mediated dilation (FMD) ... Full text Link to item Cite

UBC-Nepal expedition: phenotypical evidence for evolutionary adaptation in the control of cerebral blood flow and oxygen delivery at high altitude.

Journal Article J Physiol · June 2019 KEY POINTS: Sherpa have lived in the Nepal Himalaya for 25-40 thousand years and display positive physiological adaptations to hypoxia. Sherpa have previously been demonstrated to suffer less negative cerebral side effects of ascent to extreme altitude, ye ... Full text Link to item Cite

Validation of a noninvasive monitor to continuously trend individual responses to hypovolemia

Journal Article Russian Journal of Pediatric Surgery Anesthesia and Intensive Care · January 1, 2019 Background. Humans are able to compensate for significant blood loss with little change in traditional vital signs, limiting early detection and intervention. We hypothesized that the Compensatory Reserve Index (CRI), a new hemodynamic parameter that trend ... Full text Cite

UBC-Nepal expedition: upper and lower limb conduit artery shear stress and flow-mediated dilation on ascent to 5,050 m in lowlanders and Sherpa.

Journal Article Am J Physiol Heart Circ Physiol · December 1, 2018 The study of conduit artery endothelial adaptation to hypoxia has been restricted to the brachial artery, and comparisons with highlanders have been confounded by differences in altitude exposure, exercise, and unknown levels of blood viscosity. To address ... Full text Link to item Cite

Physiology of static breath holding in elite apneists.

Journal Article Exp Physiol · May 1, 2018 NEW FINDINGS: What is the topic of this review? This review provides an up-to-date assessment of the physiology involved with extreme static dry-land breath holding in trained apneists. What advances does it highlight? We specifically highlight the recent ... Full text Link to item Cite

A validation method for near-infrared spectroscopy based tissue oximeters for cerebral and somatic tissue oxygen saturation measurements.

Journal Article J Clin Monit Comput · April 2018 We describe the validation methodology for the NIRS based FORE-SIGHT ELITE® (CAS Medical Systems, Inc., Branford, CT, USA) tissue oximeter for cerebral and somatic tissue oxygen saturation (StO2) measurements for adult subjects submitted to the United Stat ... Full text Link to item Cite

Competitive apnea and its effect on the human brain: focus on the redox regulation of blood-brain barrier permeability and neuronal-parenchymal integrity.

Journal Article FASEB J · April 2018 Static apnea provides a unique model that combines transient hypertension, hypercapnia, and severe hypoxemia. With apnea durations exceeding 5 min, the purpose of the present study was to determine how that affects cerebral free-radical formation and the c ... Full text Link to item Cite

Reduced left ventricular filling following blood volume extraction does not result in compensatory augmentation of cardiac mechanics.

Journal Article Exp Physiol · April 1, 2018 NEW FINDINGS: What is the central question of this study? A reduction in left ventricular (LV) filling, and concomitant increase in heart rate, augments LV mechanics to maintain stroke volume (SV); however, the impact of reduced LV filling in isolation on ... Full text Link to item Cite

UBC-Nepal Expedition: An experimental overview of the 2016 University of British Columbia Scientific Expedition to Nepal Himalaya.

Journal Article PLoS One · 2018 The University of British Columbia Nepal Expedition took place over several months in the fall of 2016 and was comprised of an international team of 37 researchers. This paper describes the objectives, study characteristics, organization and management of ... Full text Link to item Cite

Influence of lung volume on the interaction between cardiac output and cerebrovascular regulation during extreme apnoea.

Journal Article Exp Physiol · October 1, 2017 What is the central question of this study? Does the reduction in cardiac output observed during extreme voluntary apnoea, secondary to high lung volume, result in a reduction in cerebral blood flow, perfusion pressure and oxygen delivery in a group of eli ... Full text Link to item Cite

Hypercapnia is essential to reduce the cerebral oxidative metabolism during extreme apnea in humans.

Journal Article J Cereb Blood Flow Metab · September 2017 The cerebral metabolic rate of oxygen (CMRO2) is reduced during apnea that yields profound hypoxia and hypercapnia. In this study, to dissociate the impact of hypoxia and hypercapnia on the reduction in CMRO2, 11 breath-hold competitors completed three apn ... Full text Link to item Cite

Intra-Target Microdosing - A Novel Drug Development Approach: Proof of Concept, Safety, and Feasibility Study in Humans.

Journal Article Clin Transl Sci · September 2017 Intra-Target Microdosing (ITM) is a novel drug development approach aimed at increasing the efficiency of first-in-human (FIH) testing of new molecular entities (NMEs). ITM combines intra-target drug delivery and "microdosing," the subpharmacological syste ... Full text Link to item Cite

A novel paraplegia model in awake behaving macaques.

Journal Article J Neurophysiol · September 1, 2017 Lower limb paralysis from spinal cord injury (SCI) or neurological disease carries a poor prognosis for recovery and remains a large societal burden. Neurophysiological and neuroprosthetic research have the potential to improve quality of life for these pa ... Full text Link to item Cite

Forced vital capacity and not central chemoreflex predicts maximal hyperoxic breath-hold duration in elite apneists.

Journal Article Respir Physiol Neurobiol · August 2017 The determining mechanisms of a maximal hyperoxic apnea duration in elite apneists have remained unexplored. We tested the hypothesis that maximal hyperoxic apnea duration in elite apneists is related to forced vital capacity (FVC) but not the central chem ... Full text Link to item Cite

Validation of a noninvasive monitor to continuously trend individual responses to hypovolemia.

Journal Article J Trauma Acute Care Surg · July 2017 BACKGROUND: Humans are able to compensate for significant blood loss with little change in traditional vital signs, limiting early detection and intervention. We hypothesized that the Compensatory Reserve Index (CRI), a new hemodynamic parameter that trend ... Full text Link to item Cite

β1-Blockade increases maximal apnea duration in elite breath-hold divers.

Journal Article J Appl Physiol (1985) · April 1, 2017 We hypothesized that the cardioselective β1-adrenoreceptor antagonist esmolol would improve maximal apnea duration in elite breath-hold divers. In elite national-level divers (n = 9), maximal apneas were performed in a randomized and counterbalanced order ... Full text Link to item Cite

Surviving Without Oxygen: How Low Can the Human Brain Go?

Journal Article High Alt Med Biol · March 2017 Bailey, Damian M., Christopher K. Willie, Ryan L. Hoiland, Anthony R. Bain, David B. MacLeod, Maria A. Santoro, Daniel K. DeMasi, Andrea Andrijanic, Tanja Mijacika, Otto F. Barak, Zeljko Dujic, and Philip N. Ainslie. Surviving without oxygen: how low can t ... Full text Link to item Cite

Effects of Acute, Profound Hypoxia on Healthy Humans: Implications for Safety of Tests Evaluating Pulse Oximetry or Tissue Oximetry Performance.

Journal Article Anesth Analg · January 2017 Extended periods of oxygen deprivation can produce acidosis, inflammation, energy failure, cell stress, or cell death. However, brief profound hypoxia (here defined as SaO2 50%-70% for approximately 10 minutes) is not associated with cardiovascular comprom ... Full text Link to item Cite

Cerebral oxidative metabolism is decreased with extreme apnoea in humans; impact of hypercapnia.

Journal Article J Physiol · September 15, 2016 KEY POINTS: The present study describes the cerebral oxidative and non-oxidative metabolism in man during a prolonged apnoea (ranging from 3 min 36 s to 7 min 26 s) that generates extremely low levels of blood oxygen and high levels of carbon dioxide. The ... Full text Link to item Cite

Pain Phenotypes and Associated Clinical Risk Factors Following Traumatic Amputation: Results from Veterans Integrated Pain Evaluation Research (VIPER).

Journal Article Pain Med · January 2016 OBJECTIVE: To define clinical phenotypes of postamputation pain and identify markers of risk for the development of chronic pain. DESIGN: Cross-sectional study of military service members enrolled 3-18 months after traumatic amputation injury. SETTING: Mil ... Full text Open Access Link to item Cite

Role of cerebral blood flow in extreme breath holding.

Journal Article Transl Neurosci · 2016 The role of cerebral blood flow (CBF) on a maximal breath-hold (BH) in ultra-elite divers was examined. Divers (n = 7) performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg) ... Full text Link to item Cite

Peripheral chemoreflex inhibition with low-dose dopamine: new insight into mechanisms of extreme apnea.

Journal Article Am J Physiol Regul Integr Comp Physiol · November 1, 2015 The purpose of this study was to determine the impact of peripheral chemoreflex inhibition with low-dose dopamine on maximal apnea time, and the related hemodynamic and cerebrovascular responses in elite apnea divers. In a randomized order, participants pe ... Full text Link to item Cite

Individual-Specific, Beat-to-beat Trending of Significant Human Blood Loss: The Compensatory Reserve.

Journal Article Shock · August 2015 Current monitoring technologies are unable to detect early, compensatory changes that are associated with significant blood loss. We previously introduced a novel algorithm to calculate the Compensatory Reserve Index (CRI) based on the analysis of arterial ... Full text Link to item Cite

End tidal-to-arterial CO2 and O2 gas gradients at low- and high-altitude during dynamic end-tidal forcing.

Journal Article Am J Physiol Regul Integr Comp Physiol · June 1, 2015 We sought to characterize and quantify the performance of a portable dynamic end-tidal forcing (DEF) system in controlling the partial pressure of arterial CO2 (Pa(CO2)) and O2 (Pa(O2)) at low (LA; 344 m) and high altitude (HA; 5,050 m) during an isooxic C ... Full text Link to item Cite

The contribution of arterial blood gases in cerebral blood flow regulation and fuel utilization in man at high altitude.

Journal Article J Cereb Blood Flow Metab · May 2015 The effects of partial acclimatization to high altitude (HA; 5,050 m) on cerebral metabolism and cerebrovascular function have not been characterized. We hypothesized (1) increased cerebrovascular reactivity (CVR) at HA; and (2) that CO2 would affect cereb ... Full text Link to item Cite

Regulation of brain blood flow and oxygen delivery in elite breath-hold divers.

Journal Article J Cereb Blood Flow Metab · January 2015 The roles of involuntary breathing movements (IBMs) and cerebral oxygen delivery in the tolerance to extreme hypoxemia displayed by elite breath-hold divers are unknown. Cerebral blood flow (CBF), arterial blood gases (ABGs), and cardiorespiratory metrics ... Full text Link to item Cite

Influence of high altitude on cerebral blood flow and fuel utilization during exercise and recovery.

Journal Article J Physiol · December 15, 2014 We examined the hypotheses that: (1) during incremental exercise and recovery following 4-6 days at high altitude (HA) global cerebral blood flow (gCBF) increases to preserve cerebral oxygen delivery (CDO2) in excess of that required by an increasing cereb ... Full text Link to item Cite

Impact of hypocapnia and cerebral perfusion on orthostatic tolerance.

Journal Article J Physiol · December 1, 2014 We examined two novel hypotheses: (1) that orthostatic tolerance (OT) would be prolonged when hyperventilatory-induced hypocapnia (and hence cerebral hypoperfusion) was prevented; and (2) that pharmacological reductions in cerebral blood flow (CBF) at base ... Full text Link to item Cite

The accuracy of a near-infrared spectroscopy cerebral oximetry device and its potential value for estimating jugular venous oxygen saturation.

Journal Article Anesth Analg · December 2014 BACKGROUND: An intriguing potential clinical use of cerebral oximeter measurements (SctO2) is the ability to noninvasively estimate jugular bulb venous oxygen saturation (SjvO2). Our purpose in this study was to determine the accuracy of the FORE-SIGHT(®) ... Full text Link to item Cite

Effects of elevated oxygen and carbon dioxide partial pressures on respiratory function and cognitive performance.

Journal Article J Appl Physiol (1985) · August 15, 2014 Hyperoxia during diving has been suggested to exacerbate hypercapnic narcosis and promote unconsciousness. We tested this hypothesis in male volunteers (12 at rest, 10 at 75 W cycle ergometer exercise) breathing each of four gases in a hyperbaric chamber. ... Full text Link to item Cite

Stability of cerebral metabolism and substrate availability in humans during hypoxia and hyperoxia.

Journal Article Clin Sci (Lond) · May 2014 Characterization of the influence of oxygen availability on brain metabolism is an essential step toward a better understanding of brain energy homoeostasis and has obvious clinical implications. However, how brain metabolism depends on oxygen availability ... Full text Link to item Cite

Regional cerebral blood flow in humans at high altitude: gradual ascent and 2 wk at 5,050 m.

Journal Article J Appl Physiol (1985) · April 1, 2014 The interindividual variation in ventilatory acclimatization to high altitude is likely reflected in variability in the cerebrovascular responses to high altitude, particularly between brain regions displaying disparate hypoxic sensitivity. We assessed reg ... Full text Link to item Cite

Resting pulmonary haemodynamics and shunting: a comparison of sea-level inhabitants to high altitude Sherpas.

Journal Article J Physiol · March 15, 2014 The incidence of blood flow through intracardiac shunt and intrapulmonary arteriovenous anastomoses (IPAVA) may differ between Sherpas permanently residing at high altitude (HA) and sea-level (SL) inhabitants as a result of evolutionary pressure to improve ... Full text Link to item Cite

Accuracy of the Lifebox pulse oximeter during hypoxia in healthy volunteers.

Journal Article Anaesthesia · December 2013 Pulse oximetry is a standard of care during anaesthesia in high-income countries. However, 70% of operating environments in low- and middle-income countries have no pulse oximeter. The 'Lifebox' oximetry project set out to bridge this gap with an inexpensi ... Full text Link to item Cite

The in-vivo oxyhaemoglobin dissociation curve at sea level and high altitude.

Journal Article Respir Physiol Neurobiol · March 1, 2013 Animals native to hypoxic environments have adapted by increasing their haemoglobin oxygen affinity, but in-vitro studies of the oxyhaemoglobin dissociation curve (ODC) in humans show no changes in affinity under physiological conditions at altitudes up to ... Full text Link to item Cite

Development and validation of a cerebral oximeter capable of absolute accuracy.

Journal Article J Cardiothorac Vasc Anesth · December 2012 OBJECTIVE: Cerebral oximetry may be a valuable monitor, but few validation data are available, and most report the change from baseline rather than absolute accuracy, which may be affected by individuals whose oximetric values are outside the expected rang ... Full text Link to item Cite

Inhaled fentanyl aerosol in healthy volunteers: pharmacokinetics and pharmacodynamics.

Journal Article Anesth Analg · November 2012 BACKGROUND: Rapid delivery of potent opioid to the systemic circulation is an important feature for the effective treatment of acute and acute-on-chronic breakthrough pain. The delivery of different opioids by the pulmonary route has been inconsistent, usu ... Full text Link to item Cite

Regional brain blood flow in man during acute changes in arterial blood gases.

Journal Article J Physiol · July 15, 2012 Despite the importance of blood flow on brainstem control of respiratory and autonomic function, little is known about regional cerebral blood flow (CBF) during changes in arterial blood gases.We quantified: (1) anterior and posterior CBF and reactivity th ... Full text Link to item Cite

Surgical capacity building in Uganda through twinning, technology, and training camps.

Journal Article World J Surg · June 2011 BACKGROUND: Neurosurgical capacity is extremely deficient in East African countries where 27 neurosurgeons serve more than 250 million people. To build capacity, the Duke University Medical Center and New Mulago Hospital in Uganda applied a two-pronged twi ... Full text Link to item Cite

Acoustic Radiation Force Impulse (ARFI) imaging-based needle visualization.

Journal Article Ultrason Imaging · January 2011 Ultrasound-guided needle placement is widely used in the clinical setting, particularly for central venous catheter placement, tissue biopsy and regional anesthesia. Difficulties with ultrasound guidance in these areas often result from steep needle insert ... Full text Link to item Cite

On the feasibility of imaging peripheral nerves using acoustic radiation force impulse imaging.

Journal Article Ultrason Imaging · July 2009 Regional anesthesia is preferred over general anesthesia for many surgical procedures; however, challenges associated with poor image guidance limit its widespread acceptance as a viable alternative. In B-mode ultrasound images, the current standard for gu ... Full text Link to item Cite

The novel use of computer-generated virtual imaging to assess the difficult pediatric airway.

Journal Article Anesth Analg · May 2007 In a patient with a known difficult airway, history and examination may be of limited use in formulating a management plan for subsequent tracheal intubation. Further detailed and descriptive review of the airway is necessary. Virtual imaging is a recent a ... Full text Link to item Cite

Changes in hematocrit based on incremental blood sampling: mathematical models perform poorly.

Journal Article Can J Anaesth · April 2005 Featured Publication PURPOSE: Excessive blood sampling, with its inherent risks, is of growing concern among clinicians. We performed this study to measure the changes in hematocrit (Hct) during a laboratory investigation where multiple blood samples are collected. The perform ... Full text Link to item Cite

The desaturation response time of finger pulse oximeters during mild hypothermia.

Journal Article Anaesthesia · January 2005 Featured Publication Pulse oximeters may delay displaying the correct oxygen saturation during the onset of hypoxia. We investigated the desaturation response times of pulse oximeter sensors (forehead, ear and finger) during vasoconstriction due to mild hypothermia and vasodil ... Full text Link to item Cite

Dexmedetomidine pharmacodynamics: Part II: Crossover comparison of the analgesic effect of dexmedetomidine and remifentanil in healthy volunteers.

Journal Article Anesthesiology · November 2004 Featured Publication BACKGROUND: Dexmedetomidine is a highly selective alpha2-adrenoceptor agonist used for short-term sedation of mechanically ventilated patients. The analgesic profile of dexmedetomidine has not been fully characterized in humans. METHODS: This study was des ... Full text Link to item Cite

Dexmedetomidine pharmacodynamics: part I: crossover comparison of the respiratory effects of dexmedetomidine and remifentanil in healthy volunteers.

Journal Article Anesthesiology · November 2004 Featured Publication BACKGROUND: Dexmedetomidine, a highly selective alpha2-adrenoceptor agonist used for short-term sedation of mechanically ventilated patients, has minimal effect on ventilation. METHODS: This study compared the respiratory effect of dexmedetomidine to that ... Full text Link to item Cite

Dexmedetomidine infusion for sedation during fiberoptic intubation: a report of three cases.

Journal Article J Clin Anesth · March 2004 We report three patients undergoing cervical spine surgery who required awake fiberoptic intubation, and in whom sedation was provided using a dexmedetomidine infusion. Dexmedetomidine was used to provide a moderate level of sedation without causing respir ... Full text Link to item Cite

Infectious complications.

Journal Article Reg Anesth Pain Med · 2004 Full text Link to item Cite

Variability in determination of point of needle insertion in peripheral nerve blocks: a comparison of experienced and inexperienced anaesthetists.

Journal Article Anaesthesia · July 2003 Accurate identification of surface landmarks is essential for the successful performance of peripheral nerve blocks. The variability between experienced and inexperienced practitioners in identifying anatomical landmarks has not been studied previously. An ... Full text Link to item Cite

A study of anesthetic drug utilization in different age groups.

Journal Article J Clin Anesth · May 2003 STUDY OBJECTIVE: To determine anesthetic drug utilization in different age groups. DESIGN: Retrospective, automated, intraoperative database study. SETTING: Tertiary care medical center. MEASUREMENTS: 30,842 noncardiac general anesthesia case records betwe ... Full text Link to item Cite

Central nervous system toxicity following the administration of levobupivacaine for lumbar plexus block: A report of two cases.

Journal Article Reg Anesth Pain Med · 2003 BACKGROUND AND OBJECTIVES: Central nervous system and cardiac toxicity following the administration of local anesthetics is a recognized complication of regional anesthesia. Levobupivacaine, the pure S(-) enantiomer of bupivacaine, was developed to improve ... Full text Link to item Cite

Severe phantom leg pain in an amputee after lumbar plexus block.

Journal Article Reg Anesth Pain Med · 2003 OBJECTIVES: To describe the onset of phantom leg pain in an amputee with the performance of a lumbar plexus block and the subsequent alleviation after the performance of a sciatic nerve block. CASE REPORT: A 72-year-old American Society of Anesthesiologist ... Full text Link to item Cite

Knotted peripheral nerve catheter.

Journal Article Reg Anesth Pain Med · 2003 Full text Link to item Cite

A new teaching model for resident training in regional anesthesia.

Journal Article Anesth Analg · November 2002 Featured Publication UNLABELLED: The adequacy of resident education in regional anesthesia is of national concern. A teaching model to improve resident training in regional anesthesia was instituted in the Anesthesiology Residency in 1996 at Duke University Health System. The ... Full text Link to item Cite

Magnesium: Physiology and pharmacology (multiple letters) [10]

Journal Article British Journal of Anaesthesia · December 9, 1999 Cite

Magnesium: physiology and pharmacology.

Journal Article Br J Anaesth · December 1999 Link to item Cite

Three-dimensional magnetic resonance imaging of thoracic and lumbar paravertebral space in human cadavers

Journal Article Regional Anesthesia and Pain Medicine · January 1, 1999 INTRODUCTION: Several investigators have attempted to spatially visualize the paravertebral space (PVS) in humans. Most 3D models of the PVS are illustrations based on standard anatomical textbooks. Two-dimensional models of the PVS have been reconstructed ... Full text Cite