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Spectral Reflectance as a Unique Tissue Identifier in Healthy Humans and Inhalation Injury Subjects
Tracheal intubation is the preferred method of airway management, a common emergency trauma medicine problem. Currently, methods for confirming tracheal tube placement are lacking, and we propose a novel technology, spectral reflectance, which may be incorporated into the tracheal tube for verification of placement. Previous work demonstrated a unique spectral profile in the trachea, which allowed differentiation from esophageal tissue in ex vivo swine, in vivo swine, and human cadavers. The goal of this study is to determine if spectral reflectance can differentiate between trachea and other airway tissues in living humans and whether the unique tracheal spectral profile persists in the presence of an inhalation injury. Reflectance spectra were captured using a custom fiber-optic probe from the buccal mucosa, posterior oropharynx, and trachea of healthy humans intubated for third molar extraction and from the trachea of patients admitted to a burn intensive care unit with and without inhalation injury. Using ratio comparisons, we found that the tracheal spectral profile was significantly different from buccal mucosa or posterior oropharynx, but the area under the curve values are not high enough to be used clinically. In addition, inhalation injury did not significantly alter the spectral reflectance of the trachea. Further studies are needed to determine the utility of this technology in a clinical setting and to develop an algorithm for tissue differentiation.
Journal Article
Dressing up : fashion week NYC
Lee Friedlander (b. 1934) is one of the most renowned photographers of his generation. Through Friedlander's lens, people in their everyday environments are transformed into arresting portraits, and the banal features of roadsides, storefronts, and city streets become vivid scenery. In Dressing Up, Friedlander ventures into new territory, turning his eye to the rarefied world of fashion and revealing precisely what is commonplace about it: behind the glamorous spectacle of the runway are many people hard at work. The photographs, commissioned by the New York Times Magazine, were taken in 2006 during New York Fashion Week, when the artist spent time backstage at the Marc Jacobs, Donna Karan, Calvin Klein, Zac Posen, Oscar de la Renta, and Proenza Schouler shows. The resulting images, many of which are published here for the first time, depict a flurry of toiling stylists, dressers, makeup artists, photographers, and models-all of them preparing, but not quite prepared, for an image to be taken. Lovers of photography and high-end fashion will be surprised and intrigued by this inside glimpse into the world of runway design.
BOOK
Spectral Reflectance Can Differentiate Tracheal and Esophageal Tissue in the Presence of Bodily Fluids and Soot
Endotracheal intubation is a common life-saving procedure implemented in emergency care to ensure patient oxygenation, but it is difficult and often performed in suboptimal conditions leading to high rates of patient complications. Undetected misplacement in the esophagus is a preventable complication that can lead to fatalities in 5–10% of patients who undergo emergency intubation. End-tidal carbon dioxide monitoring and other proper placement detection methods are useful, yet the problem of misplacement persists. Our previous work demonstrated the utility of spectral reflectance sensors for differentiating esophageal and tracheal tissues, which can be used to confirm proper endotracheal tube placement. In this study, we examine the effectiveness of spectral characterization in the presence of saline, blood, “vomit”, and soot in the trachea. Our results show that spectral properties of the trachea that differentiate it from the esophagus persist in the presence of these substances. This work further confirms the potential usefulness of this novel detection technology in field applications.
Journal Article
Ralph Lemon
Ralph Lemon (born 1952) is one of the most significant figures to emerge from New Yorks downtown dance and performance world in the past 40 years. A polymath and shape-shifter, Lemon combines dance and theater with drawing, film, writing and ethnography in works presented on the stage, in publications and in museums. He builds his politically resonant and deeply personal projects in collaboration with dance makers and artists from New York, West Africa, South and East Asia, and the American South. Lemon, who was born in Cincinnati and raised in Minneapolis, describes his explorations as a \"search for the forms of formlessness.\" Absorbing and transmuting fractured mythologies, social history and dance techniques from multiple geographies and decades, Lemons genre-transcending works perform an alchemy of past and present, reality and fantasy. This book, the first monograph on the artist, features a wide range of texts by scholars and performers, an original photo essay by Lemon and an extensive chronology.
BOOK
Effects of a novel acetaminophen analog on cardiorespiratory compensatory responses and survival in a male rat model of traumatic hemorrhage
When pain is associated with traumatic hemorrhage, medics must be concerned about secondary effects of analgesics on cardiorespiratory systems. A novel analog of acetaminophen, D‐112, was developed to circumvent liver toxicity and improve analgesic efficacy. D‐112 causes dose‐related inhibition of formalin‐induced licking. The objective of this study was to test the effects of D‐112 on survival and cardiorespiratory variables following hemorrhage and extremity trauma (ET). We hypothesized that D‐112 would significantly change cardiorespiratory responses to HEM and thereby decrease survival. Male rats received either vehicle (lactated Ringer's) or D‐112 (50 mg/kg) after conscious hemorrhage of either 37% ( n = 10, vehicle and D‐112) or 50% ( n = 8, vehicle; n = 11, D‐112) of blood volume following ET, which consisted of soft tissue injury and fibula fracture. Rats were observed for 4 h after the start of hemorrhage. Neither survival times (37% hemorrhage: p = 0.474; 50% hemorrhage: p = 0.306) nor survival curves (37% hemorrhage: p = 0.146; 50% hemorrhage: p = 0.280) differed between treatments. Mean arterial pressure did not differ between treatments (37% hemorrhage: p = 0.742; 50% hemorrhage: p = 0.521). D‐112 transiently elevated minute ventilation ( p < 0.001) after both hemorrhages. D‐112 does not alter cardiorespiratory responses to the point of depressing survival, suggesting that D‐112 could be an appropriate analgesic following traumatic hemorrhage.
Journal Article
Autonomic mechanisms associated with heart rate and vasoconstrictor reserves
Introduction
Hemorrhage is accompanied by baroreflex-mediated tachycardia and vasoconstriction. The difference between baseline and maximum responses is defined as the heart rate (HR) and vasoconstrictor ‘reserve’.
Objective
To test the hypothesis that higher HR and vasoconstrictor reserves in subjects with high tolerance (HT) to central hypovolemia is associated with greater reserve for sympathoexcitation and vagal withdrawal compared with low tolerant (LT) subjects.
Methods
R–R intervals (RRI), systolic arterial pressure (SAP), estimated stroke volume, and muscle sympathetic nerve activity (MSNA) were measured during lower body negative pressure (LBNP) designed to induce pre-syncope. Subjects with tolerance ≤60 mmHg LBNP were classified as LT (
n
= 22) while subjects who tolerated LBNP levels >60 mmHg were classified as HT (
n
= 56). Spontaneous cardiac baroreflex sensitivity (BRS) was assessed via RRI-SAP down–down sequences.
Results
HR reserve in HT subjects (+52 ± 2 bpm) was twofold greater (
P
< 0.001) than that in LT subjects (+27 ± 3 bpm). Vasoconstrictor reserve in the HT group (+3.4 ± 0.5 pru) was greater (
P
= 0.04) than that of the LT group (+1.9 ± 0.3 pru). HT subjects demonstrated greater (
P
≤ 0.03) BRS reserve (−14.2 ± 1.8 ms/mmHg) and MSNA reserve (+41 ± 2 bursts/min) compared with LT subjects (−7.4 ± 1.7 ms/mmHg and +26 ± 7 bursts/min).
Interpretation
Our data support the hypothesis that greater physiological reserve capacity for tachycardia and vasoconstriction related to high tolerance to central hypovolemia is associated with greater reserves for sympathoexcitation and cardiac vagal withdrawal.
Journal Article
Platelet Activation after Presyncope by Lower Body Negative Pressure in Humans
Central hypovolemia elevates hemostatic activity which is essential for preventing exsanguination after trauma, but platelet activation to central hypovolemia has not been described. We hypothesized that central hypovolemia induced by lower body negative pressure (LBNP) activates platelets. Eight healthy subjects were exposed to progressive central hypovolemia by LBNP until presyncope. At baseline and 5 min after presyncope, hemostatic activity of venous blood was evaluated by flow cytometry, thrombelastography, and plasma markers of coagulation and fibrinolysis. Cell counts were also determined. Flow cytometry revealed that LBNP increased mean fluorescence intensity of PAC-1 by 1959±455 units (P<0.001) and percent of fluorescence-positive platelets by 27±18%-points (P = 0.013). Thrombelastography demonstrated that coagulation was accelerated (R-time decreased by 0.8±0.4 min (P = 0.001)) and that clot lysis increased (LY60 by 6.0±5.8%-points (P = 0.034)). Plasma coagulation factor VIII and von Willebrand factor ristocetin cofactor activity increased (P = 0.011 and P = 0.024, respectively), demonstrating increased coagulation activity, while von Willebrand factor antigen was unchanged. Plasma protein C activity and tissue-type plasminogen activator increased (P = 0.007 and P = 0.017, respectively), and D-dimer increased by 0.03±0.02 mg l(-1) (P = 0.031), demonstrating increased fibrinolytic activity. Plasma prothrombin time and activated partial thromboplastin time were unchanged. Platelet count increased by 15±13% (P = 0.014) and red blood cells by 9±4% (P = 0.002). In humans, LBNP-induced presyncope activates platelets, as evidenced by increased exposure of active glycoprotein IIb/IIIa, accelerates coagulation. LBNP activates fibrinolysis, similar to hemorrhage, but does not alter coagulation screening tests, such as prothrombin time and activated partial thromboplastin time. LBNP results in increased platelet counts, but also in hemoconcentration.
Journal Article
Rhabdomyolysis After Prolonged Tourniquet Application Is Associated with Reversible Acute Kidney Injury (AKI) in Rats
Extremity trauma, including ischemia (e.g., prolonged tourniquet application or crush), is common among battlefield injuries. Injured muscle releases toxins leading to rhabdomyolysis and, potentially, acute kidney injury (AKI). The goal of this study was to characterize sequelae of ischemic extremity injury over 72 h, focusing on time courses of rhabdomyolysis and AKI. Male Sprague Dawley rats were placed into two groups. Ischemic injury was produced in anesthetized rats using bilateral tourniquets (TK; n = 10) for 5 h; control (CON; n = 9) rats were treated identically without TK application. Indicators of rhabdomyolysis and renal function were measured in conscious rats 1 day preinjury (baseline, BL) and then at 1.5, 24, 48, and 72 h post-TK release. Prolonged TK application produced necrosis in both muscle and bone marrow but not in kidney. The wet/dry weights indicated edema in injured limbs at 72 h (4.1 (0.5) (TK) vs. 2.9 (0.1) (CON); p < 0.001). TK rats exhibited a 100-fold increase in creatine kinase activity compared to CON at 1.5 h (20,040 (7265) U/L vs. 195 (86) U/L (mean (SD); p < 0.0001). TK decreased the mean glomerular filtration rate (GFR; p < 0.001) at 1.5 h, but these values recovered by 24 h in concert with elevated urinary flow and alkalinization. Prolonged ischemic extremity injury therefore produced severe rhabdomyolysis without irreversible renal damage.
Journal Article
Testing of novel spectral device sensor in swine model of airway obstruction
Loss of a patent airway is a significant cause of prehospital death. Endotracheal intubation is the gold standard of care but has a high rate of failure and complications, making development of new devices vital. We previously showed that tracheal tissue has a unique spectral profile which could be utilized to confirm correct airway device placement. Therefore, the goals of this study were twofold: 1‐ to develop an airway obstruction model and 2‐ use that model to assess how airway compromise affects tissue reflectance. Female swine were anesthetized, intubated, and instrumented. Pigs were allowed to breathe spontaneously and underwent either slow‐ or rapid‐onset obstruction until a real‐time pulse oximeter reading of ≤50%. At baseline, 25%, 50%, 75%, and 100% obstruction, a fiber‐optic reflection probe was inserted into the trachea and esophagus to capture reflectance spectra. Both slow‐ and rapid‐onset obstruction significantly decreased arterial oxygen concentration (sO2) and increased partial pressure of CO2 (pCO2). The presence of the tracheal‐defining spectral profile was confirmed and remained consistent despite changes in sO2 and pCO2. This study validated a model of slow‐ and rapid‐airway obstruction that results in significant hypoxia and hypercapnia. This is valuable for future testing of airway device components that may improve airway management. Additionally, our data support the ability of spectral reflectance to differentiate between tracheal and esophageal tissues in the presence of a clinical condition that decreases oxygen saturation. Endotracheal intubation is the gold standard of care but requires confirmation of correct placement. We hypothesized that white‐light reflectance may be used as a technique to confirm placement in the trachea. Our data confirm that spectral reflectance can distinguish tracheal from esophageal tissue even in the face of changing levels of oxygen and carbon dioxide during airway obstruction.
Journal Article