Cerebral oxygen availability by NIR spectroscopy during transient hypoxia in humans

1990 ◽  
Vol 69 (3) ◽  
pp. 907-913 ◽  
Author(s):  
N. B. Hampson ◽  
E. M. Camporesi ◽  
B. W. Stolp ◽  
R. E. Moon ◽  
J. E. Shook ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Volume ◽  
Near Infrared ◽  
Cerebral Blood Volume ◽  
Minute Ventilation ◽  
Nir Spectroscopy ◽  
Redox Status ◽  
Total Blood ◽  
Arterial Ph

The effects of mild hypoxia on brain oxyhemoglobin, cytochrome a,a3 redox status, and cerebral blood volume were studied using near-infrared spectroscopy in eight healthy volunteers. Incremental hypoxia reaching 70% arterial O2 saturation was produced in normocapnia [end-tidal PCO2 (PETCO2) 36.9 +/- 2.6 to 34.9 +/- 3.4 Torr] or hypocapnia (PETCO2 32.8 +/- 0.6 to 23.7 +/- 0.6 Torr) by an 8-min rebreathing technique and regulation of inspired CO2. Normocapnic hypoxia was characterized by progressive reductions in arterial PO2 (PaO2, 89.1 +/- 3.5 to 34.1 +/- 0.1 Torr) with stable PETCO2, arterial PCO2 (PaCO2), and arterial pH and resulted in increases in heart rate (35%) systolic blood pressure (14%), and minute ventilation (5-fold). Hypocapnic hypoxia resulted in progressively decreasing PaO2 (100.2 +/- 3.6 to 28.9 +/- 0.1 Torr), with progressive reduction in PaCO2 (39.0 +/- 1.6 to 27.3 +/- 1.9 Torr), and an increase in arterial pH (7.41 +/- 0.02 to 7.53 +/- 0.03), heart rate (61%), and ventilation (3-fold). In the brain, hypoxia resulted in a steady decline of cerebral oxyhemoglobin content and a decrease in oxidized cytochrome a,a3. Significantly greater loss of oxidized cytochrome a,a3 occurred for a given decrease in oxyhemoglobin during hypocapnic hypoxia relative to normocapnic hypoxia. Total blood volume response during hypoxia also was significantly attenuated by hypocapnia, because the increase in volume was only half that of normocapnic subjects. We conclude that cytochrome a,a3 oxidation level in vivo decreases at mild levels of hypoxia. PaCO is an important determinant of brain oxygenation, because it modulates ventilatory, cardiovascular, and cerebral O2 delivery responses to hypoxia.

Quantitation of cerebral blood volume in human infants by near-infrared spectroscopy

1990 ◽  
Vol 68 (3) ◽  
pp. 1086-1091 ◽  
Author(s):  
J. S. Wyatt ◽  
M. Cope ◽  
D. T. Delpy ◽  
C. E. Richardson ◽  
A. D. Edwards ◽  
...  
Keyword(s):  
Blood Volume ◽  
Near Infrared ◽  
Cerebral Blood Volume ◽  
Arterial Oxygen Saturation ◽  
Newborn Infants ◽  
Nir Spectroscopy ◽  
Hemoglobin Concentration ◽  
Large Vessel ◽  
Arterial Oxygen ◽  
Human Infants

Current methods for measuring cerebral blood volume (CBV) in newborn infants are unsatisfactory. A new method is described in which the effect of a small change (5-10%) in arterial oxygen saturation (SaO2) on cerebral oxyhemoglobin [HbO2] and deoxyhemoglobin [Hb] concentration is observed by near-infrared (NIR) spectroscopy. Previous experiments in which the NIR absorption characteristics of HbO2 and Hb and the pathlength of NIR light through the brain were defined allowed changes in [HbO2] and [Hb] to be quantified from the Beer-Lambert law. It is shown here that CBV can then be derived from the expression CBV = (delta[HbO2] - delta[Hb])/(2. delta SaO2.H.R.), where H is the large vessel total hemoglobin concentration and R to the cerebral-to-large vessel hematocrit ratio. Observations on 12 newborn infants with normal brains, born at 25-40 wk of gestation and aged 10-240 h, gave a mean value for CBV of 2.22 +/- 0.40 (SD) ml/100 g, whereas mean CBV was significantly higher 3.00 +/- 1.04 ml/100 g in 10 infants with brain injury born at 24 to 42 wk of gestation and aged 4-168 h (P less than 0.05).

Effects of rapid mannitol infusion on cerebral blood volume

1986 ◽  
Vol 64 (1) ◽  
pp. 104-113 ◽  
Author(s):  
Patrick Ravussin ◽  
David P. Archer ◽  
Jane L. Tyler ◽  
Ernst Meyer ◽  
Mounir Abou-Madi ◽  
...  
Keyword(s):  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Human Subjects ◽  
Venous Pressure ◽  
Hemoglobin Concentration ◽  
Rapid Infusion ◽  
Total Blood ◽  
Content Type ◽  
Positron Emission

✓ Positron emission tomography was used to study the effect of a rapid infusion of mannitol on cerebral blood volume (CBV) in five dogs and in three human subjects. The ability of mannitol to reduce intracranial pressure (ICP) has always been attributed to its osmotic dehydrating effect. The effects of mannitol infusion include increased osmolality, total blood volume, central venous pressure (CVP), and cerebral blood flow, and decreased hematocrit, hemoglobin concentration, serum sodium level, and viscosity. Mannitol's ability to dilate the cerebral vasculature, either directly or indirectly, and thus to transiently increase ICP, is a subject of controversy. By in vivo labeling of red cells with carbon-11, the authors were able to demonstrate an early increase in CBV in dogs of 20%, 27%, and 23% (mean increase, p < 0.05) at 1, 2, and 3 minutes, respectively, after an infusion of 20% mannitol (2 gm/kg over a 3-minute period). The animals' muscle blood volume increased by 27% (mean increase, p < 0.05) 2 minutes after infusion. In the human subjects, lower doses and a longer duration of infusion (1 gm/kg over 4 minutes) resulted in an increase in CBV of 8%, 14% (p < 0.05), and 10% at 1, 2, and 3 minutes, respectively, after infusion. In dogs, ICP increased by 4 mm Hg (mean increase, p < 0.05) 1 minute after the infusion, before decreasing sharply. The ICP was not measured in the human subjects. Hematocrit, hemoglobin, sodium, potassium, osmolality, heart rate, mean arterial pressure (MAP), and CVP were measured serially. Results of these measurements, as well as the significant decrease in MAP that occurred after mannitol infusion, are discussed. This study demonstrated that rapid mannitol infusion increases CBV and ICP. The increase in muscle blood volume, in the presence of a decreased MAP and an adequate CVP, suggests that mannitol may have caused vasodilation in these experiments.

MR-GUIDED PULSE OXIMETRY IMAGING OF BREAST IN VIVO

2011 ◽  
Vol 04 (02) ◽  
pp. 199-208
Author(s):  
ZHIQIU LI ◽  
SHUDONG JIANG ◽  
VENKATARAMANAN KRISHNASWAMY ◽  
SCOTT C. DAVIS ◽  
SUBHADRA SRINIVASAN ◽  
...  
Keyword(s):  
Breast Tissue ◽  
Near Infrared ◽  
Imaging System ◽  
Structural Information ◽  
Human Subjects ◽  
Nir Spectroscopy ◽  
Tomography System ◽  
Finger Pulse ◽  
Lock In

A near-infrared (NIR) tomography system with spectrally-encoded sources in two wavelength bands was built to quantify the temporal oxyhemoglobin and deoxyhemoglobin contrast in breast tissue at a 20 Hz bandwidth. The system was integrated into a 3 T magnetic resonance (MR) imaging system through a customized breast coil interface for simultaneous optical and MRI acquisition. In this configuration, the MR images provide breast tissue structural information for NIR spectroscopy of adipose and fibro-glandular tissue in breast. Spectral characterization performance of the NIR system was verified through dynamic phantom experiments. Normal human subjects were imaged with finger pulse oximeter (PO) plethysmogram synchronized to the NIR system to provide a frequency-locked reference. Both the raw data from the NIR system and the recovered absorption coefficients of the breast at two wavelengths showed the same frequency of about 1.3 Hz as the PO output. The frequency lock-in approach provided a practical platform for MR-localized recovery of small pulsatile variations of oxyhemoglobin and deoxyhemoglobin in the breast, which are related to the heartbeat and vascular resistance of the tissue.

scholarly journals Biocellulose Masks as Delivery Systems: A Novel Methodological Approach to Assure Quality and Safety

Cosmetics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 66 ◽  
Author(s):  
Paola Perugini ◽  
Mariella Bleve ◽  
Fabiola Cortinovis ◽  
Antonio Colpani
Keyword(s):  
Light Scattering ◽  
Bacterial Cellulose ◽  
Near Infrared ◽  
Gas Permeability ◽  
Methodological Approach ◽  
Safety Evaluation ◽  
Nir Spectroscopy ◽  
Quality And Safety ◽  
Multiple Light Scattering

Bacterial cellulose (BC) has become of great interest in recent years, as a delivery system in several areas of application, including food, drugs, and cosmetics, thanks to its exclusive advantages, such as high biocompatibility, water holding capacity, and good gas permeability. The novel approach of the authors has led to a protocol for checking the quality and safety of bacterial cellulose matrices in the manufacture of cosmetic masks. Two non-destructive techniques, near-infrared spectroscopy (NIR) and multiple light scattering (MLS), were used to verify different parameters affecting the quality of BC sheets, allowing cellulose masks to be checked over time. NIR spectroscopy allowed for discovering changes in the water content, depending on filling/packaging procedures, like flat-folding. Multiple light scattering was used to ascertain the stability of solutions in contact with masks. From a clinical standpoint, the cutaneous tolerability of biocellulose masks, and their effect on skin parameters, were evaluated through some specific “in vivo” tests. Also, a safety evaluation during application was conducted through different studies: a short-term one after single application, and a long-term one upon continued use.

A near-infrared reversible fluorescent probe for real-time imaging of redox status changes in vivo

2013 ◽  
Vol 4 (3) ◽  
pp. 1079 ◽  
Author(s):  
Kehua Xu ◽  
Mingming Qiang ◽  
Wen Gao ◽  
Ruixian Su ◽  
Na Li ◽  
...  
Keyword(s):  
Real Time ◽  
Fluorescent Probe ◽  
Near Infrared ◽  
Redox Status ◽  
Real Time Imaging

scholarly journals Cerebrovascular responses of the rat brain to noxious stimuli as examined by functional near-infrared whole brain imaging

2012 ◽  
Vol 107 (10) ◽  
pp. 2853-2865 ◽  
Author(s):  
Ji-Wei He ◽  
Fenghua Tian ◽  
Hanli Liu ◽  
Yuan Bo Peng
Keyword(s):  
Brain Imaging ◽  
Near Infrared ◽  
Small Animal ◽  
Nir Spectroscopy ◽  
Brain Regions ◽  
Anterior Cingulate ◽  
Hemodynamic Changes ◽  
Whole Brain ◽  
Brain Hemodynamics

While near-infrared (NIR) spectroscopy has been increasingly used to detect stimulated brain activities with an advantage of dissociating regional oxy- and deoxyhemoglobin concentrations simultaneously, it has not been utilized much in pain research. Here, we investigated and demonstrated the feasibility of using this technique to obtain whole brain hemodynamics in rats and speculated on the functional relevance of the NIR-based hemodynamic signals during pain processing. NIR signals were emitted and collected using a 26-optodes array on rat's dorsal skull surface after the removal of skin. Following the subcutaneous injection of formalin (50 μl, 3%) into a hindpaw, several isolable brain regions showed hemodynamic changes, including the anterior cingulate cortex, primary/secondary somatosensory cortexes, thalamus, and periaqueductal gray ( n = 6). Time courses of hemodynamic changes in respective regions matched with the well-documented biphasic excitatory response. Surprisingly, an atypical pattern (i.e., a decrease in oxyhemoglobin concentration with a concomitant increase in deoxyhemoglobin concentration) was seen in phase II. In a separate group of rats with innocuous brush and noxious pinch of the same area ( n = 11), results confirmed that the atypical pattern occurred more likely in the presence of nociception than nonpainful stimulation, suggesting it as a physiological substrate when the brain processes pain. In conclusion, the NIR whole brain imaging provides a useful alternative to study pain in vivo using small-animal models. Our results support the notion that neurovascular response patterns depend on stimuli, bringing attention to the interpretation of vascular-based neuroimaging data in studies of pain.

scholarly journals Can Cerebral Blood Volume Be Measured Reproducibly with an Improved near Infrared Spectroscopy System?

2001 ◽  
Vol 21 (2) ◽  
pp. 110-113 ◽  
Author(s):  
Marjo J. T. Van de Ven ◽  
Willy N. J. M. Colier ◽  
Marco C. van der Sluijs ◽  
Diederik Walraven ◽  
Berend Oeseburg ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Infrared Spectroscopy ◽  
Blood Volume ◽  
Near Infrared Spectroscopy ◽  
Healthy Subjects ◽  
Baseline Level ◽  
Near Infrared ◽  
Cerebral Blood Volume ◽  
Spectroscopy System

In some circumstances, cerebral blood volume (CBV) can be used as a measure for cerebral blood flow. A new near infrared spectroscope was used for determining the reproducibility of CBV measurements assessed by the O2-method. Twenty-seven healthy subjects were investigated. An intrasubject coefficient of variation (CV) was calculated, based on four identical episodes of desaturation–resaturation (O2-method) procedures for CBV measurements. Two trials were performed, with (trial 1) and without (trial 2) disconnecting the equipment. A mean CV of 12.6% and 10.0% was found in trial 1 and 2, respectively. Cerebral blood volume values yield 3.60 ± 0.82 mL 100 g−1. Cerebral blood volume could be measured reproducible in adults using near infrared spectroscopy, if the arterial desaturation is limited to approximately 5% from baseline level.

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