Biomedical subjects

Jangwoen Lee

Publications and source records attributed to Jangwoen Lee.

4 recordsLinked to original sources

PubMed2007

Potential interference by hydroxocobalamin on cooximetry hemoglobin measurements during cyanide and smoke inhalation treatments.

STUDY OBJECTIVE: Concentrated aqueous solutions of hydroxocobalamin (OHCob) are administered intravenously for cyanide poisoning victims, many of whom also have concurrent smoke inhalation. Because of its intense light absorbance in visible wavelengths (absorption peak at 532 nm), we investigate potential interference effects of OHCob on total hemoglobin concentration (tHb), carboxyhemoglobin (COHb), methemoglobin (MetHb), and oxyhemoglobin (Hb-O2) cooximetry measurement values in blood. METHODS: In vivo cooximetry measurements were conducted with 3 specific pathogen-free white New Zealand rabbits (3.80+/-0.21 kg) during the intravenous infusion of OHCob (625 mg during a 100-minute period). Resultant changes in tHb, Hb-O2, COHb, and MetHb values were measured and correlated with respect to estimated in vivo OHCob concentrations. In vitro measurements were conducted with rabbit blood to confirm in vivo measurements. RESULTS: The introduction of OHCob clearly interfered with the cooximetry measurements of each of the hemoglobin component fractions in whole blood and resulted in altered measurement values from the baseline values. The presence of OHCob in blood interferes with cooximetry measurements of COHb, MetHb, and Hb-O2. The increase in measured COHb fraction with increasing concentrations of OHCob was most notable. CONCLUSION: The presence of OHCob in blood interferes with cooximetry measurements of COHb, MetHb, and Hb-O2. These effects need to be considered during OHCob treatment of cyanide poisoning, particularly in smoke inhalation victims with potential for concurrent carbon monoxide exposure, because it may lead to potentially erroneous reported COHb levels.

Animals↗

PubMed2006

Broadband diffuse optical spectroscopy measurement of hemoglobin concentration during hypovolemia in rabbits.

Serial blood draws for the assessment of trauma patients' hemoglobin (sHgb) and hematocrit (sHct) is standard practice. A device that would allow for continuous real-time, non-invasive monitoring of hemoglobin and tissue perfusion would potentially improve recognition, monitoring and resuscitation of blood loss. We developed a device utilizing diffuse optical spectroscopy (DOS) technology that simultaneously measures tissue scattering and near-infrared (NIR) absorption to obtain non-invasive measurements of oxy- (Hb-O(2)), deoxyhemoglobin (Hb-R) concentrations and tissue hemoglobin concentration (THC) in an animal model of hypovolemic shock induced by successive blood withdrawals. Intubated New Zealand White rabbits (N = 16) were hemorrhaged via a femoral arterial line every 20 min until a 20% blood loss (10-15 cc kg(-1)) was achieved to attain hypovolemia. A broadband DOS probe placed on the inner thigh was used to measure muscle concentrations of Hb-O(2) and Hb-R, during blood withdrawal. THC and tissue hemoglobin saturation (S(T)O(2)) were calculated from DOS [Hb-O(2)] and [Hb-R]. Broadband DOS-measured values were compared against traditional invasive measurements: systemic sHgb, arterial oxygen saturation (S(a)O(2)) and venous oxygen saturation (S(v)O(2)) drawn from arterial and central venous blood. DOS and traditional invasive measurements versus blood loss were closely correlated (r(2) = 0.96) showing a decline with removal of blood. S(T)O(2) and [Hb-O(2)] followed similar trends with hemorrhage, while [Hb-R] remained relatively constant. These measurements may be limited to some extent by the inability to distinguish between hemoglobin and myoglobin contributions to DOS signals in tissue at this time. Broadband DOS provides a potential platform for reliable non-invasive measurements of tissue oxygenated and deoxygenated hemoglobin and may accurately reflect the degree of systemic hypovolemia and compromised tissue perfusion.

Animals↗

PubMed2005

Noninvasive in vivo monitoring of methemoglobin formation and reduction with broadband diffuse optical spectroscopy.

We present noninvasive, quantitative in vivo measurements of methemoglobin formation and reduction in a rabbit model using broadband diffuse optical spectroscopy (DOS). Broadband DOS combines multifrequency frequency-domain photon migration (FDPM) with time-independent near infrared (NIR) spectroscopy to quantitatively measure bulk tissue absorption and scattering spectra between 600 nm and 1,000 nm. Tissue concentrations (denoted by brackets) of methemoglobin ([MetHb]), deoxyhemoglobin ([Hb-R]), and oxyhemoglobin ([HbO2]) were determined from absorption spectra acquired in "real time" during nitrite infusions in nine pathogen-free New Zealand White rabbits. As little as 30 nM [MetHb] changes were detected for levels of [MetHb] that ranged from 0.80 to 5.72 microM, representing 2.2 to 14.9% of the total hemoglobin content (%MetHb). These values agreed well with on-site ex vivo cooximetry data (r2= 0.902, P < 0.0001, n = 4). The reduction of MetHb to functional hemoglobins was also carried out with intravenous injections of methylene blue (MB). As little as 10 nM changes in [MB] were detectable at levels of up to 150 nM in tissue. Our results demonstrate, for the first time, the ability of broadband DOS to noninvasively quantify real-time changes in [MetHb] and four additional chromophore concentrations ([Hb-R], [HbO2], [H2O], and [MB]) despite significant overlapping spectral features. These techniques are expected to be useful in evaluating dynamics of drug delivery and therapeutic efficacy in blood chemistry, human, and preclinical animal models.

Animals↗

PubMed2002

Three-dimensional fluorescence enhanced optical tomography using referenced frequency-domain photon migration measurements at emission and excitation wavelengths.

The ultimate success of near-infrared optical tomography rests on the precise measurement of light propagation within tissues or random media, the accurate prediction of these measurements from a light propagation model, and an efficient three-dimensional solution of the inverse imaging problem. To date, optical tomography algorithms have focused on frequency-domain photon migration (FDPM) measurements of phase-delay and amplitude attenuation, which are reported relative to the incident light, even though phase-delay and amplitude of incident light are nearly impossible to measure directly. In this contribution, we examine referenced, fluorescence-enhanced frequency-domain photon migration measured at excitation and/or emission wavelengths and report on a measurement strategy to minimize measurement and calibration error for efficient coupling of data to a distorted Born iterative imaging algorithm. We examine three referencing approaches and develop associated inversion algorithms for (1) normalizing detected emission FDPM data to the predicted emission wave arising from a homogeneous medium, (2) referencing detected emission FDPM data to that detected at a reference point, and (3) referencing detected emission FDPM data to detected excitation FDPM data detected at a reference point. Our results show the latter approach to be practical while reducing the nonlinearity of the inverse problem. Finally, in light of our results, we demonstrate the method for eliminating the influence of source strength and instrument functions for effective fluorescence-enhanced optical tomography using FDPM.

Computer Simulation↗