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Papers by jenny freeman

Introduction: Flow-volume loops (FVLs) are used to diagnose and monitor the progression and treat... more Introduction: Flow-volume loops (FVLs) are used to diagnose and monitor the progression and treatment of lung disorders such as COPD and asthma. The gold standard for generating FVLs is a spirometry-based forced vital capacity test, which requires the use of a mouthpiece or facemask and patient cooperation to generate maximum effort breaths. These tests cannot be performed by young children and adults unable to follow instructions. For these patients, the use of tidal breathing flow-volume loops (TBFVLs) has been proposed but has not been widely adopted due to lack of a reliable, non-invasive, technological solution. An impedance-based respiratory volume monitor (RVM) non-invasively measures minute ventilation and can be used to generate TBFVLs. The objectives of this study were: 1) to use a spirometer to evaluate TBFVLs measured by the RVM in healthy volunteers and 2) to monitor TBFVLs in post-operative patients using only the RVM over an extended period of time.

Trauma, 2014

Background Respiratory decompensation is common after traumatic thoracic injuries such as multipl... more Background Respiratory decompensation is common after traumatic thoracic injuries such as multiple rib fractures and pulmonary contusions. A continuous, non-invasive, impedance-based respiratory volume monitor generates right and left tidal volume measurements, reflecting air exchange in the lungs and derives an instantaneous respiratory rate. The feasibility of using unilateral respiratory volume monitor–based tidal impedance measurements to monitor respiratory status in trauma patients is evaluated. Methods Three intensive care unit patients with three or more rib fractures following blunt trauma had continuous respiratory volume monitor measurements with a novel non-invasive impedance-based device (ExSpiron, Respiratory Motion Inc., Waltham, MA) and corresponding clinical data to permit analysis. Tidal impedance measurements were collected from both the injured and non-injured sides and converted into bilateral respiratory volume monitor measurements using advanced algorithms. Re...

Journal of clinical medicine research, 2017

Patients who have undergone cardiac surgery are generally mechanically ventilated postoperatively... more Patients who have undergone cardiac surgery are generally mechanically ventilated postoperatively. Early postoperative extubation is currently recommended in anesthesia guidelines. No current technology can accurately, non-invasively, measure respiratory competence after extubation. Pulse oximetry has been helpful, but this is a late indicator of respiratory compromise. A novel, non-invasive, respiratory volume monitor (RVM) has been shown to deliver accurate continuous, real-time minute ventilation (MV), tidal volume (TV) and respiratory rate (RR) measurements and provide an objective measure of respiratory competence. The RVM will accurately reflect MV, TV and RR in cardiac surgery patients before and after extubation. RVM traces were recorded from patients before and after cardiac surgery. Continuous monitoring began on admission to the unit and was ended at 24 h after extubation. RVM-based MV, TV and RR were calculated from 30-s segments. MV, TV and RR were also continuously rec...

Diabetes Technology & Therapeutics, 2003

Hyperspectral imaging (HSI) has been useful in monitoring several medical conditions, which to da... more Hyperspectral imaging (HSI) has been useful in monitoring several medical conditions, which to date have generally involved local changes in skin oxygenation of isolated regions of interest such as skin flaps or small burns. Here, by contrast, we present a study in which HSI was used to assess the local cutaneous manifestations of significant systemic events. HSI of the ventral surface of the lower jaw was used to monitor changes in skin oxygenation during hypovolemic shock induced by hemorrhage with additional pulmonary contusion injury in a porcine model, and to monitor the subsequent recovery of oxygenation with resuscitation. Quantitative and qualitative changes were observed in the level of skin oxygenation during shock and recovery. Quantitative values were obtained by fitting reference spectra of oxyhemoglobin and deoxyhemoglobin to sample spectra. Qualitative changes included changes in the observed spatial distribution or pattern of skin oxygenation. A mottled pattern of oxygen saturation was observed during hemorrhagic shock, but not observed during hypovolemic shock or following resuscitation. Historically, the assessment of skin color and mottling has been an important, albeit inexact, component of resuscitation algorithms. Now, it is possible to analyze these variables during shock and resuscitation in an objective manner. The clinical utility of these advances needs to be determined.

The Lancet, 2005

Background Changes in the large vessels and microcirculation of the diabetic foot are important i... more Background Changes in the large vessels and microcirculation of the diabetic foot are important in the development of foot ulceration and subsequent failure to heal existing ulcers. We investigated whether oxygen delivery and muscle metabolism of the lower extremity were factors in diabetic foot disease.

The Journal of Trauma: Injury, Infection, and Critical Care, 2006

Background: Skin color changes and mottling are frequently described signs of hemorrhagic shock (... more Background: Skin color changes and mottling are frequently described signs of hemorrhagic shock (HEM). Based on this, we developed a noninvasive, noncontact hyperspectral imaging system (HSI), which quantifies and depicts the surface tissue saturation of oxygen (S HSI O 2) for each pixel in a region of interest (ROI). Our purpose was to assess HSI in a porcine HEM model. We hypothesized that HEM would cause decreases in S HSI O 2 of the skin. Methods: The HyperMed HSI system employs a spectral separator to vary the wavelength of light admitted to a digital camera. During image acquisition, a "hypercube" of images, each at a separate wavelength, is generated (at 5-nm intervals, from 500 to 600 nm). Then, the visible light spectrum for each pixel in the hypercube is compared by linear regression to standard spectra for oxyhemoglobin (OxyHb) and deoxyhemoglobin (DeoxyHb). The resulting fit coefficients for OxyHb and DeoxyHb are used to calculate S HSI O 2 values for each pixel in the ROI. The mean values for OxyHb, DeoxyHb, and S HSI O 2 across the ROI are calculated. Grayscale S HSI O 2 pictures of the ROI are also generated, in which the brightness of each pixel is proportional to its value. Seventeen pigs, 36.4 ؎ 0.11 kg, underwent standard preparation, and were maintained on ketamine and isoflurane. Normothermia was maintained (37°C to 39°C). The hemorrhage group (HEM, n ‫؍‬ 9) underwent three blood withdrawals, each 10 mL/kg, with 15 minutes between withdrawals. After the third withdrawal, animals were resuscitated with lactated Ringer's and then shed blood. The control group (CTRL, n ‫؍‬ 8) received intravenous fluids at 100 mL/h. HSI images were obtained of the inner hindlimb throughout. Results: All HEM animals showed linear decreases in both mean S HSI O 2 and OxyHb values with blood loss, which were reversed by resuscitation. These changes were evident on the grayscale S HSI O 2 pictures, but not to the naked eye, and paralleled those of invasively obtained arterial base excess and mixed venous oxygen saturation. Conclusions: HSI is a promising noninvasive and noncontact tool for quantifying changes in skin oxygenation during HEM and resuscitation.

Cancer Biology & Therapy, 2007

Introduction. Adequate evaluation of breast tumor resection at surgery continues to be an importa... more Introduction. Adequate evaluation of breast tumor resection at surgery continues to be an important issue in surgical care, as over 30% of postoperative tumors recur locally unless radiation is used to destroy remaining tumor cells in the field. Medical Hyperspectral Imaging (MHSI) delivers near-real time images of biomarkers in tissue, providing an assessment of pathophysiology and the potential to distinguish different tissues based on spectral characteristics. Methods. We have used an experimental DMBA-induced rat breast tumor model to examine the intraoperative utility of MHSI, in distinguishing tumor from normal breast and other tissues. Rats bearing tumors underwent surgical exposure and MHSI imaging, followed by partial resection of the tumors, then MHSI imaging of the resection bed, and finally total resection of tumors and of grossly normal-appearing glands. Resected tissue underwent gross examination, MHSI imaging, and histopathological evaluation. Results. An algorithm based on spectral characteristics of tissue types was developed to distinguish between tumor and normal tissues. Tissues including tumor, blood vessels, muscle, and connective tissue were clearly identified and differentiated by MHSI. Fragments of residual tumor 0.5-1 mm in size intentionally left in the operative bed were readily identified. MHSI demonstrated a sensitivity of 89% and a specificity of 94% for detection of residual tumor, comparable to that of histopathological examination of the tumor bed (85% and 92%, respectively). Conclusion. We conclude that MHSI may be useful in identifying small residual tumor in a tumor resection bed and for indicating areas requiring more extensive resection and more effective biopsy locations to the surgeon. AbbreviAtions BCT, breast-conserving treatment; CCD, charge-coupled device; DMBA, 1, 2-dimethyl benz(a)anthracene; HSI, Hyperspectral imaging; MHSI, Medical Hyperspectral Imaging introduction And bAckground Hyperspectral imaging (HSI) is a remote-sensing spectroscopic method that generates a map of a region of interest based on local biomarkers. In essence, HSI is a method of "imaging spectroscopy" combining the chemical specificity of spectroscopy with the spatial resolution of imaging. 1 Light is separated into narrow wavelength bands using a spectral separator and collected on a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) sensor as an image. A two-dimensional image is created with spectral data inherent in each pixel. The spectrum of each pixel can be correlated with biomarkers, such as oxyhemoglobin and deoxyhemoglobin. These data can then be interpreted as a "gradient map" of these biomarkers located near the tissue surface. HSI has long been used in non-medical applications, including satellite investigation to indicate areas of chemical weapons production and to assess the condition of agricultural fields. Biological tissues also have optical signatures that reflect their chemical characteristics, and HSI has recently been applied to the investigation of physiologic and pathologic changes in living tissue in animal and human studies, to provide information as to the health or disease of tissue. As a non-contact, camera-based, near-real time tool, HSI is able to interface with patients in a wide variety of settings, and in a range of medical arenas, including application as a diagnostic or a monitoring tool during surgery. For example, HSI has been shown to accurately predict viability and survival of tissue deprived of adequate perfusion, 2-4 by measuring systemic, local and regional microvascular changes that occur with diabetes, 5 and with cancer. 6-8

Diabetes Care, 2007

OBJECTIVE—Foot ulceration is a serious complication of diabetes, and new techniques that can pred... more OBJECTIVE—Foot ulceration is a serious complication of diabetes, and new techniques that can predict wound healing may prove very helpful. We tested the ability of medical hyperspectral technology (HT), a novel diagnostic scanning technique that can quantify tissue oxy- and deoxyhemoglobin to predict diabetic foot ulcer healing. RESEARCH DESIGN AND METHODS—Ten type 1 diabetic patients with 21 foot ulcer sites, 13 type 1 diabetic patients without ulcers, and 14 nondiabetic control subjects were seen up to 4 times over a 6-month period. HT measurements of oxyhemoglobin (HT-oxy) and deoxyhemoglobin (HT-deoxy) were performed at or near the ulcer area and on the upper and lower extremity distant from the ulcer. An HT healing index for each site was calculated from the HT-oxy and -deoxy values. RESULTS—Hyperspectral tissue oxygenation measurements observed changes in tissue immediately surrounding the ulcer when comparing ulcers that heal and ulcers that do not heal (P < 0.001). The se...

Journal of Clinical Monitoring and Computing, 2014

Continuous respiratory assessment is especially important during post-operative care following ex... more Continuous respiratory assessment is especially important during post-operative care following extubation. Respiratory depression and subsequent adverse outcomes can arise due to opioid administration and/or residual anesthetics. A non-invasive respiratory volume monitor (RVM) has been developed that provides continuous, real-time, measurements of minute ventilation (MV), tidal volume (TV), and respiratory rate (RR) via a standardized set of thoracic electrodes. Previous work demonstrated accuracy of the RVM versus standard spirometry and its utility in demonstrating response to opioids in postoperative patients. This study evaluated the correlation between RVM measurements of MV, TV and RR to ventilator measurements during general anesthesia (GA). Continuous digital RVM and ventilator traces, as well as RVM measurements of MV, TV and RR, were analyzed from ten patients (mean 62.6 ± 7.4 years; body mass index 28.6 ± 5.2 kg/m 2) undergoing surgery with GA. RVM data were compared to ventilator data and bias, precision and accuracy were calculated. The average MV difference between the RVM and ventilator was-0.10 L/min (bias:-1.3 %, precision: 6.6 %, accuracy: 9.0 %. The average TV difference was 40 mL (bias: 0.4 %, precision: 7.3 %, accuracy: 9.1 %). The average RR difference was-0.22 breaths/ minute (bias:-1.8 %, precision: 3.7 % accuracy: 4.1 %). Correlations between the RVM traces and the ventilator were compared at various points with correlations[0.90 throughout. Pairing the close correlation to ventilator measurements in intubated patients demonstrated by this study with previously described accuracy compared to spirometry in nonintubated patients, the RVM can be considered to have the capability to provide continuity of ventilation monitoring post-extubation This supports the use of real-time continuous

Journal of Trauma and Acute Care Surgery, 2014

BACKGROUND: Opioid-induced respiratory depression (OIRD) and postoperative apnea (POA) can lead t... more BACKGROUND: Opioid-induced respiratory depression (OIRD) and postoperative apnea (POA) can lead to complications after surgery or traumatic injury. Previously, real-time monitoring of respiratory insufficiency and identification of apneic events have been difficult. A noninvasive respiratory volume monitor (RVM) that reports minute ventilation (MV), tidal volume, and respiratory rate is now available. The RVM was used to report the effect of opioids on respiratory status as well as demonstrate apneic breathing patterns in a hospital postanesthesia care unit. METHODS: RVM traces were collected from 132 patients. Predicted MV (MV PRED) for each patient was used to calculate and the ''percent predicted'' MV (MV MEASURED / MV PRED Â 100%) before opioid administration. Patients were stratified patients into two categories: ''at risk,'' MV of less than 80% MV PRED , and ''not at risk,'' MV of 80% MV PRED or greater. After opioid dosing, patients with MV of less than 40% MV PRED were categorized as ''unsafe.'' POA was defined as more than five apneic or hypopneic events per hour. RESULTS: Of the 132 patients, 50 received opioids. Baseline MV was 7.2 T 0.5 L/min. The MV-based protocol classified 18 of 50 patients as at risk before opioid administration. After the first opioid dose administration, at-risk patients experienced an average MV decrease (36.7% T 8.5% MV PRED) and 13 of 18 decreased into unsafe; the 32 not at-risk patients experienced a lesser average MV decrease (76.9% T 6.3% MV PRED). Only 1 of 32 not at-risk patients had a decrease in MV to unsafe. The proposed protocol had a sensitivity of 93% and a specificity of 86%. Of the 132 patients, 26 displayed POA. Of the 26 patients, 12 experienced POA without receiving opioids. Of the 26 patients with POA, 14 also received opioids, and of those, 6 were classified as unsafe. CONCLUSION: This investigation indicates that at risk and unsafe respiratory patterns occur frequently after procedure. RVM provides continuous noninvasive objective measurements of OIRD and POA. The RVM may prove a useful tool in opioid dosing and in recognition and management of POA and strong potential value in the rapid detection of OIRD and apnea in the contemporary combat casualty environment.

CHEST Journal, 2014

ABSTRACT Critical Care Posters ISESSION TYPE: Poster PresentationsPRESENTED ON: Saturday, March 2... more ABSTRACT Critical Care Posters ISESSION TYPE: Poster PresentationsPRESENTED ON: Saturday, March 22, 2014 at 01:15 PM - 02:15 PMPURPOSE: Opioid-induced respiratory depression (OIRD) and post-operative apnea (POA), can lead to increased post-operative complications. Identification of OIRD and POA remains difficult with current monitoring technology. A novel, non-invasive, Respiratory Volume Monitor (RVM) that provides continuous, real-time, measurements of minute ventilation (MV), tidal volume (TV) and respiratory rate (RR), is now available. The RVM was utilized to detect the effect of opioids on respiratory status and apneic breathing patterns. Digital respiratory traces were collected from 132 patients. The predicted MV (MVPRED) for each patient was calculated based on BSA. The MV measured, prior to opioid administration, by the RVM (MVMEASURED) was used to calculate the "Percent Predicted" MV (MVMEAS /MVPRED x100%). Patients were then stratified into two categories: "At-Risk", MV <80% MVPRED and "Not-at-Risk", MV >80% MVPRED. After opioid dosing, patients with MV less than 40% MVPRED were categorized as "Un-Safe". POA was defined as >5 apneic or hypopneic events (no detected breaths; or a TV reduction > 50% lasting >10 seconds) per hour. 50/132 patients received opioids. Baseline MV was 7.2±0.5 L/min, (93.1%±6.1% MVPRED). A MV-based protocol classified 18 of the 50 patients as "At-Risk" prior to opioid. After the first opioid dose "At-Risk" patients experienced an average MV decrease to 36.7%±8.5% of MVPRED whereas 32 "Not-at-Risk" patients experienced an average MV decrease to 76.9%±6.3% of MVPRED. In 13 of the 18 patients classified as "At-Risk", MV decreased into the "Un-Safe" range after opioid. Only 1/32 patients identified as "Not-at-Risk" had a decrease in MV to "Un-Safe". The protocol had a sensitivity of 93%, specificity of 86% and negative predictive value of 97%. 26 of the 132 patients displayed POA. 14 of the 26 patients with POA also received opioids; 6 of these 14 demonstrated an "Un-Safe" MV after opioid administration. Twelve patients experienced POA without receiving opioids. This study demonstrates that "At-Risk" and "Un-Safe" respiratory patterns occur frequently in the PACU and have the potential to continue once patients are transferred to the floor. RVM provides continuous non-invasive measurements that quantify respiration in patients and objectively report OIRD and POA. The use of RVM can aid in decision-making regarding opioid use recognition and management of apnea, with the potential for decreasing complications and cost and improving patient safety. Diane Ladd: Employee: Repiratory Motion, Inc Jenny Freeman: Employee: Respiratory Motion, Inc., Shareholder: Respiratory Motion, Inc. The following authors have nothing to disclose: Edward GeorgeNo Product/Research Disclosure Information.

CHEST Journal, 2012

PURPOSE: Respiratory monitoring in recently extubated patients is suboptimal. There is no clinica... more PURPOSE: Respiratory monitoring in recently extubated patients is suboptimal. There is no clinically useful leading indicator of impending respiratory failure. A Respiratory Volume Monitor (RVM) has been developed to deliver continuous, realtime respiratory volume and rate data. This study aims to test the accuracy of the RVM monitor over a 24 hour period in a cohort of adult subjects.