scholarly journals Perfusion Changes at the Forehead Measured by Photoplethysmography during a Head-Down Tilt Protocol

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 71
Author(s):  
Tomas Ysehak Abay ◽  
Kamran Shafqat ◽  
Panayiotis A. Kyriacou
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Venous Blood ◽  
Arterial Oxygen ◽  
Large Variability ◽  
Large Vein ◽  
The Subject ◽  
Induced Changes

Photoplethysmography (PPG) signals from the forehead can be used in pulse oximetry as they are less affected by vasoconstriction compared to fingers. However, the increase in venous blood caused by the positioning of the patient can deteriorate the signals and cause erroneous estimations of the arterial oxygen saturation. To date, there is no method to measure this venous presence under the PPG sensor. This study investigates the feasibility of using PPG signals from the forehead in an effort to estimate relative changes in haemoglobin concentrations that could reveal these posture-induced changes. Two identical reflectance PPG sensors were placed on two different positions on the forehead (above the eyebrow and on top of a large vein) in 16 healthy volunteers during a head-down tilt protocol. Relative changes in oxygenated ( Δ HbO 2 ), reduced ( Δ HHb) and total ( Δ tHb) haemoglobin were estimated from the PPG signals and the trends were compared with reference Near Infrared Spectroscopy (NIRS) measurements. Also, the signals from the two PPG sensors were analysed in order to reveal any difference due to the positioning of the sensor. Δ HbO 2 , Δ HHb and Δ tHb estimated from the forehead PPGs trended well with the same parameters from the reference NIRS. However, placing the sensor over a large vasculature reduces trending against NIRS, introduces biases as well as increases the variability of the changes in Δ HHb. Forehead PPG signals can be used to measure perfusion changes to reveal venous pooling induced by the positioning of the subject. Placing the sensor above the eyebrow and away from large vasculature avoids biases and large variability in the measurements.

scholarly journals Wearable Near-Infrared Spectroscopy as a Physiological Monitoring Tool for Seals under Anaesthesia

2021 ◽  
Vol 13 (18) ◽  
pp. 3553
Author(s):  
Eva-Maria Bønnelycke ◽  
Gordon Hastie ◽  
Kimberley Bennett ◽  
Jana Kainerstorfer ◽  
Ryan Milne ◽  
...  
Keyword(s):  
Heart Rate ◽  
Infrared Spectroscopy ◽  
Real Time ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Physiological Monitoring ◽  
Monitoring Tool ◽  
Concentration Changes

Chemical immobilisation of pinnipeds is a routine procedure in research and veterinary practice. Yet, there are inevitable risks associated with chemical immobilisation, and the physiological response to anaesthetic agents in pinnipeds remains poorly understood. The current study used wearable continuous-wave near-infrared spectroscopy (NIRS) data from 10 trials of prolonged anaesthesia (0.5 to 1.4 h) induced through ketamine and midazolam in five grey seals (Halichoerus grypus) involved in other procedures. The aim of this study was to (1) analyse the effect of each compound on heart rate, arterial oxygen saturation (SpO2), and relative concentration changes in oxygenated [ΔO2Hb] and deoxygenated haemoglobin [ΔHHb] in cerebral tissue and (2) to investigate the use of NIRS as a real-time physiological monitoring tool during chemical immobilisation. Average group responses of ketamine (n = 27) and midazolam (n = 11) administrations were modelled using generalised additive mixed models (GAMM) for each dependent variable. Following ketamine and midazolam administration, [ΔHHb] increased and [ΔO2Hb] remained relatively stable, which was indicative of apnoea. Periods of apnoea were confirmed from respiratory band data, which were simultaneously collected during drugging trials. Given that SpO2 remained at 97% during apnoea, we hypothesized that increasing cerebral [ΔHHb] was a result of venous congestion as opposed to decreased oxygen delivery. Changes in heart rate were limited and appeared to be driven by the individual pharmacological actions of each drug. Future research could include simultaneous measures of metabolic rate, such as the relative change in concentration of cytochrome-c-oxidase, to guide operators in determining when apnoea should be considered prolonged if changes in [ΔHHb] and [ΔO2Hb] occur beyond the limits recorded in this study. Our findings support the use of NIRS as real-time physiological monitoring tool during pinniped chemical immobilisation, which could assist veterinarians and researchers in performing safe anaesthetic procedures.

Quantification of adult cerebral hemodynamics by near-infrared spectroscopy

1994 ◽  
Vol 77 (6) ◽  
pp. 2753-2760 ◽  
Author(s):  
C. E. Elwell ◽  
M. Cope ◽  
A. D. Edwards ◽  
J. S. Wyatt ◽  
D. T. Delpy ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Cerebral Hemodynamics ◽  
Arterial Oxygen ◽  
The Mean

Near-infrared spectroscopy was used to measure global cerebral blood flow and volume in 10 healthy adult volunteers. High- and low-cerebral blood flow compartments were detected with mean flows for all 10 subjects of 59 +/- 21 (SD) and 11 +/- 4 ml.100 g-1.min-1, respectively. The mean cerebral blood volume of the group was 2.85 +/- 0.97 ml/100 g. Analysis of spontaneous changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin demonstrated strong correlations between respiratory rate and the oscillation frequency of cerebral oxyhemoglobin concentration (r = 0.99) and arterial oxygen saturation (SaO2) (r = 0.99). An estimate of the mean cerebral oxygen saturation for all subjects averaged 59.4 +/- 12.4% when their mean SaO2 was 91.8 +/- 2.4% (equivalent to 67.6 +/- 13.8% at a normoxic SaO2 of 98%). These results demonstrate that near-infrared spectroscopy can be used as a noninvasive bedside technique for both qualitative and quantitative evaluation of cerebral hemodynamics and oxygenation in adults.

Arterial and Venous Contributions to Near-infrared Cerebral Oximetry

2000 ◽  
Vol 93 (4) ◽  
pp. 947-953 ◽  
Author(s):  
H. Marc Watzman ◽  
C. Dean Kurth ◽  
Lisa M. Montenegro ◽  
Jonathan Rome ◽  
James M. Steven ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Frequency Domain ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Fixed Ratio ◽  
Cerebral Oximetry ◽  
Infrared Light ◽  
Arterial Oxygen

Background Cerebral oximetry is a noninvasive bedside technology using near-infrared light to monitor cerebral oxygen saturation (Sco2) in an uncertain mixture of arteries, capillaries, and veins. The present study used frequency domain near-infrared spectroscopy to determine the ratio of arterial and venous blood monitored by cerebral oximetry during normoxia, hypoxia, and hypocapnia. Methods Twenty anesthetized children aged < 8 yr with congenital heart disease of varying arterial oxygen saturation (Sao2) were studied during cardiac catheterization. Sco2, Sao2, and jugular bulb oxygen saturation (Sjo2) were measured by frequency domain near-infrared spectroscopy and blood oximetry at normocapnia room air, normocapnia 100% inspired O2, and hypocapnia room air. Results Among subject conditions, Sao2 ranged from 68% to 100%, Sjo2 from 27% to 96%, and Sco2 from 29% to 92%. Sco2 was significantly related to Sao2 (y = 0. 85 x -17, r = 0.47), Sjo2 (y = 0.77 x +13, r = 0.70), and the combination (Sco2 = 0.46 Sao2 + 0.56 Sjo2 - 17, R = 0.71). The arterial and venous contribution to cerebral oximetry was 16 +/- 21% and 84 +/- 21%, respectively (where Sco2 = alpha Sao2 + beta Sjo2 with alpha and beta being arterial and venous contributions). The contribution was similar among conditions but differed significantly among subjects (range, approximately 40:60 to approximately 0:100, arterial:venous). Conclusions Cerebral oximetry monitors an arterial/venous ratio of 16:84, similar in normoxia, hypoxia, and hypocapnia. Because of biologic variation in cerebral arterial/venous ratios, use of a fixed ratio is not a good method to validate the technology.

scholarly journals Cerebral perfusion and oxygenation are impaired by folate deficiency in rat: Absolute measurements with noninvasive near-infrared spectroscopy

2011 ◽  
Vol 31 (6) ◽  
pp. 1482-1492 ◽  
Author(s):  
Bertan Hallacoglu ◽  
Angelo Sassaroli ◽  
Sergio Fantini ◽  
Aron M Troen
Keyword(s):  
Cognitive Impairment ◽  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Hemoglobin Concentration ◽  
Microvascular Dysfunction ◽  
Common Finding ◽  
Arterial Oxygen

Brain microvascular pathology is a common finding in Alzheimer's disease and other dementias. However, the extent to which microvascular abnormalities cause or contribute to cognitive impairment is unclear. Noninvasive near-infrared spectroscopy (NIRS) can address this question, but its use for clarifying the role of microvascular dysfunction in dementia has been limited due to theoretical and practical considerations. We developed a new noninvasive NIRS method to obtain quantitative, dynamic measurements of absolute brain hemoglobin concentration and oxygen saturation and used it to show significant cerebrovascular impairments in a rat model of diet-induced vascular cognitive impairment. We fed young rats folate-deficient (FD) and control diets and measured absolute brain hemoglobin and hemodynamic parameters at rest and during transient mild hypoxia and hypercapnia. With respect to control animals, FD rats featured significantly lower brain hemoglobin concentration (72±4 μmol/L versus 95±6 μmol/L) and oxygen saturation (54%±3% versus 65%±2%). By contrast, resting arterial oxygen saturation was the same for both groups (96%±4%), indicating that decrements in brain hemoglobin oxygenation were independent of blood oxygen carrying capacity. Vasomotor reactivity in response to hypercapnia was also impaired in FD rats. Our results implicate microvascular abnormality and diminished oxygen delivery as a mechanism of cognitive impairment.

scholarly journals The speed of reinfusion affects the vascular system during ozone major autohemotherapy

Ozone Therapy ◽  
2017 ◽  
Vol 1 (3) ◽  
pp. 56 ◽  
Author(s):  
Daniele Rimini ◽  
Filippo Molinari ◽  
William Liboni ◽  
Vincenzo Simonetti ◽  
Marianno Franzini
Keyword(s):  
Infrared Spectroscopy ◽  
Side Effects ◽  
Near Infrared Spectroscopy ◽  
Transcranial Doppler ◽  
Near Infrared ◽  
Vascular System ◽  
Venous Blood ◽  
Blood Drawing

Ozone major autohemotherapy (O-MAHT) is a way of ozonetherapy administration consisting of drawing patient’s venous blood, mixing with oxygen/ozone, and reinfusing it into the vein. Some ozone therapists reported side effects during the O-MAHT, but the origin has not been described yet. We investigated the effect of blood drawing velocity during O-MAHT to see its effects on the vascular system and symptomatology. We administered O-MAHT to 11 subjects, and we interleaved fast and slow reinfusions. We monitored cerebral macrocirculation with transcranial Doppler (TCD) and tissue microcirculation with near-infrared spectroscopy (NIRS). Annoying symptoms appeared just during the fast reinfusion periods. NIRS and TCD parameters revealed vasoconstriction during fast reinfusion and improved metabolism during slow reinfusion. Overall, our investigation well discriminated fast from slow reinfusion velocity.

Noninvasive measurement of forearm blood flow and oxygen consumption by near-infrared spectroscopy

1994 ◽  
Vol 76 (3) ◽  
pp. 1388-1393 ◽  
Author(s):  
R. A. De Blasi ◽  
M. Ferrari ◽  
A. Natali ◽  
G. Conti ◽  
A. Mega ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Healthy Subjects ◽  
Near Infrared ◽  
Forearm Blood Flow ◽  
Vascular Occlusion ◽  
Venous Occlusion ◽  
The Subject

We applied near-infrared spectroscopy (NIRS) for the simultaneous measurement of forearm blood flow (FBF) and oxygen consumption (VO2) in the human by inducing a 50-mmHg venous occlusion. Eleven healthy subjects were studied both at rest and after hand exercise during vascular occlusion. FBF was also measured by strain-gauge plethysmography. FBF measured by NIRS was 1.9 +/- 0.8 ml.100 ml-1.min-1 at rest and 8.2 +/- 2.9 ml.100 ml-1.min-1 after hand exercise. These values showed a correlation (r = 0.94) with those obtained by the plethysmography. VO2 values were 4.6 +/- 1.3 microM O2 x 100 ml-1.min-1 at rest and 24.9 +/- 11.2 microM O2 x 100 ml-1.min-1 after hand exercise. The scatter of the FBF and VO2 values showed a good correlation between the two variables (r = 0.93). The results demonstrate that NIRS provides the particular advantage of obtaining the contemporary evaluation of blood flow and VO2, allowing correlation of these two variables by a single maneuver without discomfort for the subject.

A Review of Process near Infrared Spectroscopy: 1980–1994

1993 ◽  
Vol 1 (4) ◽  
pp. 221-245 ◽  
Author(s):  
Jerry Workman
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Literature Search ◽  
Near Infrared ◽  
Process Analysis ◽  
The State ◽  
Chronological Order ◽  
Measurement Scheme ◽  
The Subject

For this review, papers on NIR process analysis were categorised according to their overall configuration and measurement scheme. This analyser taxonomy was chosen to demonstrate the state of the current use of process analyser terms and to allow the reader to access a broad range of applications by referring to the specific measuring characteristics of the analyser. The basis for this review was a literature search covering the period from January 1980 to January 1994 on the subject of Process NIR and FT-NIR analysis. Each section is in chronological order to allow the reader to observe the development (and refinement) of process NIR from 1980 to the present.

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