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Transmission-mode pulse oximetry, the optical method for determining oxygen saturation in blood, is limited to only tissues that can be transilluminated, such as the earlobes and the fingers. The existing sensor configuration provides only singlepoint measurements, lacking 2D oxygenation mapping capability. Here, we demonstrate a flexible and printed sensor array composed of organic light-emitting diodes and organic photodiodes, which senses reflected light from tissue to determine the oxygen saturation. We use the reflectance oximeter array beyond the conventional sensing locations. The sensor is implemented to measure oxygen saturation on the forehead with 1.1% mean error and to create 2D oxygenation maps of adult forearms under pressure-cuff–induced ischemia. In addition, we present mathematical models to determine oxygenation in the presence and absence of a pulsatile arterial blood signal. The mechanical flexibility, 2D oxygenation mapping capability, and the ability to place the sensor in various locations make the reflectance oximeter array promising for medical sensing applications such as monitoring of real-time chronic medical conditions as well as postsurgery recovery management of tissues, organs, and wounds.

Brain activity during a verbal fluency task (VFT) has been the target of many functional imaging studies. Most studies using near-infrared spectroscopy (NIRS) have reported major activation in the frontal pole, but those using PET or fMRI have not. This led us to hypothesize that changes in the NIRS signals measured in the forehead during VFT were due to changes in skin blood flow. To test this hypothesis, we measured NIRS signals and the Doppler tissue blood flow signals in the foreheads of 50 participants. The measurements were performed while each participant produced words during two 60-s periods with an interval of 100s. In addition to a conventional optode separation distance of 30mm (FAR channels), we used a short distance – 5mm (NEAR channels) – to measure NIRS signals that originated exclusively from surface tissues. The oxygenated hemoglobin (oxyHb) concentration in the FAR and NEAR channels, as well as the Doppler blood flow signal, increased in a similar manner during the two periods of word production; the signal increase in the first period was twice as high as that in the second period. Accordingly, the mean changes in oxyHb concentration in the FAR channels were correlated closely with the changes in the NEAR channels (R2=0.91) and with the integrated Doppler skin blood flow signal (R2=0.94). Furthermore, task-related NIRS responses disappeared when we blocked skin blood flows by pressing a small area that covered a pair of optodes. Additionally, changes in the FAR channel signals were correlated closely with the magnitude of pulsatile waves in the Doppler signal (R2=0.92), but these signals were not highly correlated with the pulse rate (R2=0.43). These results suggest that a major part of the task-related changes in the oxyHb concentration in the forehead is due to task-related changes in the skin blood flow, which is under different autonomic control than heart rate. ► NIRS signals on the forehead are due to the VFT-related changes in skin blood flow. ► Pulsatile magnitude in Doppler signal can explain NIRS response. ► Pulsatile rate in Doppler signal did not correlate well with the NIRS response. ► The VFT-related NIRS signals would be under different autonomic control than HR.

Background Botulinum neurotoxin (BoNT) and filler injections into the highly vascularized glabellar region for aesthetical purposes are extremely common. Injections into the glabellar region without precise anatomical knowledge of its vascular and muscular topography may pose the risk of severe complications. Objectives We aimed to improve the safety and efficacy of the glabellar injections by mapping the regional muscles and vasculature in relation to the medial canthus and the defined reference lines. Methods Meticulous dissection was performed to reveal glabellar region muscles and arteries under surgical microscope, in 16 hemifaces of whom arteries are injected with red-dyed latex. Location of the angular artery (AA) along with its branches was noted in relation to glabellar muscles. Results The AA was always located superficial to the levator labii superioris alaeque nasi muscle (LLSAN) and then coursed toward the medial canthus to anastomose with the supratrochlear artery deep to the origin of the depressor supercilii (DS). The AA gave subcutaneously located central and paracentral branches coursing close to the mid-face line in 14 out of 16 hemifaces. Variable muscular connections were also present between the LLSAN, the DS and the procerus (P) muscles. No arteries were detected at the base of the medial eyebrow to which the DS, the P, and the frontalis (F) inserted. Conclusions This study provides a detailed map of muscular and vascular anatomy of the glabellar region to facilitate safe and efficient filler and BoNT injections without complications. No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Skin microcirculation provides essential insights in clinical practice. However, the specific characteristics and distribution patterns of dermal microarterioles and microvenules remain insufficiently explored. This study aimed to analyze their structural differences and distribution in the human forehead skin using an innovative intravascular dual perfusion technique combined with immunofluorescence staining to distinguish microvessel types within the dermis. Using two post-mortem cadaver specimens, lead oxide-gelatin perfusion was applied to label microarterioles, and latex was used for microvenules. Tissue sections underwent hematoxylin and eosin and immunofluorescence staining, with cluster of differentiation 31 (CD31) serving as a general vascular marker and monocarboxylate transporter 1 (MCT1) as a venule-specific marker. The analysis revealed significant structural differences between dermal layers: vessels in the deep dermis had larger diameters and thicker walls than those in the superficial layer, while microvessel density was higher in the superficial dermis. These findings demonstrate distinct patterns and significant differences in microvessel distribution between the superficial and deep dermal layers, reflecting their layer-specific functional demands. Furthermore, MCT1 was identified as a specific marker for microvenules, and a novel method combining CD31 and MCT1 immunofluorescent staining was introduced to differentiate dermal microarterioles from microvenules. These results offer valuable implications for surgical planning, skin grafting, and diagnostics related to microcirculation.

Purpose Near-infrared spectroscopy (NIRS) is widely used to investigate cerebral oxygenation and/or neural activation during physiological conditions such as exercise. However, NIRS-determined cerebral oxygenated hemoglobin (O 2 Hb) may not necessarily correspond to intracranial blood flow during dynamic exercise. To determine the selectivity of NIRS to assess cerebral oxygenation and neural activation during exercise, we examined the influence of changes in forehead skin blood flow (SkBF head ) on NIRS signals during dynamic exercise. Methods In ten healthy men (age: 20 ± 1 years), middle cerebral artery blood flow velocity (MCA V mean , via transcranial Doppler ultrasonography), SkBF head (via laser Doppler flowmetry), and cerebral O 2 Hb (via NIRS) were continuously measured. Each subject performed 60 % maximum heart rate moderate-intensity steady-state cycling exercise. To manipulate SkBF head , facial cooling using a mist of cold water (~4 °C) was applied for 3 min during steady-state cycling. Results MCA V mean significantly increased during exercise and remained unchanged with facial cooling. O 2 Hb and SkBF head were also significantly increased during exercise; however, both of these signals were lowered with facial cooling and returned to pre-cooling values with the removal of facial cooling. The changes in O 2 Hb correlated significantly with the relative percent changes in SkBF head in each individual ( r  = 0.71–0.99). Conclusions These findings suggest that during dynamic exercise NIRS-derived O 2 Hb signal can be influenced by thermoregulatory changes in SkBF head and therefore, may not be completely reflective of cerebral oxygenation or neural activation.

Purpose Pulse oximetry (SpO 2 ) measured at finger site via transmission mode may fail in situations of hypoperfusion. Forehead sensors using reflectance technology might be useful in these circumstances. We hypothesized that reflectance SpO 2 would be more accurate than finger SpO 2 in patients with severe shock. Methods A prospective observational study was conducted in an intensive care unit of a university hospital of patients in shock who were treated with high norepinephrine and/or epinephrine doses (≥0.1 μg kg −1  min −1 ). When blood gas determinations were requested, forehead SpO 2 and finger SpO 2 values were simultaneous recorded. Agreement between SpO 2 measurements with arterial saturation (SaO 2 ), obtained by blood analysis with a co-oximeter, was assessed using the Bland–Altman method. The number of outliers, defined by the formula SaO 2  − SpO 2  > ±3 %, indicated the proportion of measurements considered to be clinically unacceptable. Results Thirty-two patients were enrolled in the study. With the forehead sensor no reading failure occurred, and 140 paired data sets (forehead SpO 2 vs. SaO 2 ) were obtained. Bias and precision were +1.0 and +2.5 %, respectively, and the limits of agreement ranged from −4.0 to 6.0 %. The finger sensor failed to give a value in four cases, thus providing 136 paired data sets (finger SpO 2 vs. SaO 2 ) for analysis. Bias and precision were +1.4 and +4.8 %, respectively, and the limits of agreement ranged from −8.0 to 10.9 %. There were 21 (15 %) outliers for the forehead sensor and 43 (32 %) for the finger sensor ( P  < 0.001). Conclusions Forehead SpO 2 measurements were more accurate than finger SpO 2 when compared with SaO 2 in critically ill patients requiring high-dose vasopressor therapy and should therefore be the preferred method considered.

Endovascular embolization is the preferred treatment for carotid-cavernous fistulas (CCFs), but failure to catheterize the cavernous sinus may occur as a result of tortuosity, hypoplasia, or stenosis of the normal venous routes. In these cases, direct operative cannulation of the arterialized superior ophthalmic vein (SOV) offers an excellent alternative approach. We reviewed the records of patients who underwent surgical cannulation of the SOV in preparation for embolization and identified 10 patients with indirect CCF, all of whom presented with ocular signs and symptoms. All had previously undergone unsuccessful endovenous attempts at treatment at our institution. In the operating room, the SOV was catheterized under microscopic magnification through an eyelid or eyebrow incision, and the patients were taken directly to the angiographic suite for embolization. In 9 of 10 patients, embolization of the CCF was complete with clinical improvement. In 1 case, navigation of the catheter into the SOV proved difficult, and the procedure was aborted because of contrast extravasation after partial embolization. One patient required a small orbital osteotomy to localize the SOV. There were no clinical complications and no known recurrences. Cosmetic results were excellent in all patients. Surgical access to the superior ophthalmic vein for embolization of a CCF is an excellent and definitive alternative treatment when traditional endovenous routes are inaccessible. The operative approach to the SOV is straightforward and can be performed safely and expeditiously by the neurovascular team.

Introduction: Superficial temporal artery aneurysms (STAAs) occur in 1% of arterial aneurysms; mostly (95%) are pseudoaneurysms following trauma; true aneurysms are rare (5%); forty-five cases are reported. Aim: To report a rare case of a congenital STAAA. Case Report: A67-year-old patient recalled the existence of a true-histologically evidenced- aneurysm of the right superficial temporal artery since his childhood denying any head injury; it was resected through a horizontal skin incisure. Brain arteriesÂ’ magnetic imaging was negative. Conclusion: Spontaneous or congenital STAAs have to be removed respecting forehead lines. Intracranial vasculature must be investigated.

We aimed to assess the relationship between the clinical and biochemical parameters of perfusion and superior vena cava (SVC) flow in a prospective observational cohort study of very low birth weight (VLBW) infants. Newborns with congenital heart disease were excluded. Echocardiographic evaluation of SVC flow was performed in the first 24 h of life. Capillary refill time (forehead, sternum and toe), mean blood pressure, urine output and serum lactate concentration were also measured simultaneously. Thirty-eight VLBW infants were examined. Eight patients (21%) had SVC flow less than 40 ml/kg/min. There was a poor correlation between the capillary refill time (in all sites), mean blood pressure, urine output and SVC flow. The correlation coefficient for the serum lactate concentration was r  = −0.28, p  = 0.15. The median serum lactate concentration was 3.5 (range 2.8–8.5) vs. 2.7 (range 1.2–6.9) mmol/l ( p  = 0.01) in low flow versus normal flow states. A serum lactate concentration of >2.8 was 100% sensitive and 60% specific for detecting a low flow state. Combining a capillary refill time of >4 s with a serum lactate concentration of >4 mmol/l had a specificity of 97% for detecting a low SVC flow state. Serum lactate concentrations are higher in low SVC flow states. A capillary refill time of >4 s combined with serum lactate concentrations >4 mmol/l increased the specificity and positive and negative predictive values of detecting a low SVC flow state.

Superficial temporal artery aneurysms are rare; when they do occur, they are usually associated with head trauma. Spontaneous true aneurysms of the superficial temporal artery are extremely rare. They are classified as true aneurysms when all three layers of the vessel are found to be involved on histologic examination. Therapeutic options include conservative management, image-guided embolization, and surgical excision. We report a case of an extracranial spontaneous aneurysm of the frontal branch of the superficial temporal artery. A 20-year-old man presented with an asymptomatic, pulsatile, 1-cm forehead mass that had gradually increased in size. The aneurysm was evaluated by clinical examination and three-dimensional computed tomographic angiography. Complete resection was performed with local anesthesia. Histologic examination revealed that the aneurysm involved all three layers of the blood vessel: the tunica intima, tunica media, and tunica adventitia. No atherosclerotic changes or inflammatory cells were found. To the best of our knowledge, this is only the third reported case of a histologically verified spontaneous aneurysm of the frontal branch of the superficial temporal artery. Awareness of this rare pathology in the differential diagnosis of a forehead mass may facilitate diagnosis and prevent complications.