Long-Term Donor Site Morbidity and Flap Perfusion Following Radial versus Ulnar Forearm Free Flap-A Randomized Controlled Prospective Clinical Trial.

This clinical prospective randomized controlled study aimed to investigate the differences between Radial (RFFF) and Ulnar (UFFF) Forearm Free Flap in terms of success, performance, and donor site morbidity. Thirty patients with reconstruction of the head and neck region were included. For the first time, this study assessed flap-perfusion characteristics, donor-site-wound-healing dynamics and hand perfusion using hyperspectral imaging. Further, subjective (Likert-scale, DASH-score) and objective (grip/pinch-strength) parameters of donor site morbidity were analysed. Postoperative follow-up was performed until 6 months after index surgery. With 100% of patients, RFFF and UFFF were equally successful. Compared to surrounding reference, UFFF revealed significant lower tissue oxygenation saturation (StO2) than RFFF. Compared with UFFF, blood flow in both the thenar and hypothenar region were significantly reduced 6 months following RFFF transfer. After four weeks, 27% more patients demonstrated impaired wound healing following RFFF transfer. After 6 months, epithelial-surface continuity was restored in all patients of both groups. After 6 months, overall rates of both subjective and objective donor site morbidity were comparable between RFFF and UFFF. RFFF and UFFF both demonstrate similar success rates and HSI-perfusion dynamics following transfer. After 4 weeks, wound-healing disorder appeared significantly more often in RFFF than in UFFF; however, they became equal after 6 months. RFFF and UFFF can be considered as mutual alternatives.

Bleeding disorders in implant dentistry: a narrative review and a treatment guide.

PURPOSE: Considering a high prevalence of congenital and especially acquired bleeding disorders, their heterogeneity and the multitude of possible treatments strategies, a review of the scientific data on this topic is needed to implement a treatment guide for healthcare professionals. METHODS: A selective literature review was performed via PubMed for articles describing oral surgery / dental implant procedures in patients with congenital and acquired bleeding disorders. Out of the existing literature, potential treatment algorithms were extrapolated. RESULTS: In order to assess the susceptibility to bleeding, risk stratification can be used for both congenital and acquired coagulation disorders. This risk stratification, together with an appropriate therapeutic pathway, allows for an adequate and individualized therapy for each patient. A central point is the close interdisciplinary cooperation with specialists. In addition to the discontinuation or replacement of existing treatment modalities, local hemostyptic measures are of primary importance. If local measures are not sufficient, systemically administered substances such as desmopressin and blood products have to be used. CONCLUSIONS: Despite the limited evidence, a treatment guide could be developed by means of this narrative review to improve safety for patients and practitioners. Prospective randomized controlled trials are needed to allow the implementation of official evidence-based guidelines.

New Approach to the Old Challenge of Free Flap Monitoring-Hyperspectral Imaging Outperforms Clinical Assessment by Earlier Detection of Perfusion Failure.

In reconstructive surgery, free flap failure, especially in complex osteocutaneous reconstructions, represents a significant clinical burden. Therefore, the aim of the presented study was to assess hyperspectral imaging (HSI) for monitoring of free flaps compared to clinical monitoring. In a prospective, non-randomized clinical study, patients with free flap reconstruction of the oro-maxillofacial-complex were included. Monitoring was assessed clinically and by using hyperspectral imaging (TIVITA™ Tissue-System, DiaspectiveVision GmbH, Pepelow, Germany) to determine tissue-oxygen-saturation [StO2], near-infrared-perfusion-index [NPI], distribution of haemoglobin [THI] and water [TWI], and variance to an adjacent reference area (Δreference). A total of 54 primary and 11 secondary reconstructions were performed including fasciocutaneous and osteocutaneous flaps. Re-exploration was performed in 19 cases. A total of seven complete flap failures occurred, resulting in a 63% salvage rate. Mean time from flap inset to decision making for re-exploration based on clinical assessment was 23.1 ± 21.9 vs. 18.2 ± 19.4 h by the appearance of hyperspectral criteria indicating impaired perfusion (StO2 ≤ 32% OR StO2Δreference > -38% OR NPI ≤ 32.9 OR NPIΔreference ≥ -13.4%) resulting in a difference of 4.8 ± 5 h (p < 0.001). HSI seems able to detect perfusion compromise significantly earlier than clinical monitoring. These findings provide an interpretation aid for clinicians to simplify postoperative flap monitoring.

Hyperspectral imaging and artificial intelligence to detect oral malignancy - part 1 - automated tissue classification of oral muscle, fat and mucosa using a light-weight 6-layer deep neural network.

BACKGROUND: Hyperspectral imaging (HSI) is a promising non-contact approach to tissue diagnostics, generating large amounts of raw data for whose processing computer vision (i.e. deep learning) is particularly suitable. Aim of this proof of principle study was the classification of hyperspectral (HS)-reflectance values into the human-oral tissue types fat, muscle and mucosa using deep learning methods. Furthermore, the tissue-specific hyperspectral signatures collected will serve as a representative reference for the future assessment of oral pathological changes in the sense of a HS-library. METHODS: A total of about 316 samples of healthy human-oral fat, muscle and oral mucosa was collected from 174 different patients and imaged using a HS-camera, covering the wavelength range from 500 nm to 1000 nm. HS-raw data were further labelled and processed for tissue classification using a light-weight 6-layer deep neural network (DNN). RESULTS: The reflectance values differed significantly (p < .001) for fat, muscle and oral mucosa at almost all wavelengths, with the signature of muscle differing the most. The deep neural network distinguished tissue types with an accuracy of > 80% each. CONCLUSION: Oral fat, muscle and mucosa can be classified sufficiently and automatically by their specific HS-signature using a deep learning approach. Early detection of premalignant-mucosal-lesions using hyperspectral imaging and deep learning is so far represented rarely in in medical and computer vision research domain but has a high potential and is part of subsequent studies.

Hyperspectral Imaging to Study Dynamic Skin Perfusion after Injection of Articaine-4% with and without Epinephrine-Clinical Implications on Local Vasoconstriction.

This study aimed to investigate the dynamic skin perfusion via hyperspectral imaging (HSI) after application of Articaine-4% ± epinephrine as well as epinephrine only. After the subcutaneous injection of (A100) Articaine-4% with epinephrine 1:100,000, (A200) Articaine-4% with epinephrine 1:200,000, (Aw/o) Articaine-4% without epinephrine, and (EPI200) epinephrine 1:200,000, into the flexor side of the forearm in a split-arm design, dynamic skin perfusion measurement was performed over 120 min by determining tissue oxygen saturation (StO2) using HSI. After injection, all groups experienced a reactive hyperaemia. With A200, it took about three min for StO2 to drop below baseline. For Aw/o and EPI200, perfusion reduction when compared to baseline was seen at 30 min with vasoconstriction >120 min. A100 caused vasodilation with hyperaemia >60 min. After three minutes, the perfusion pattern differed significantly (p < 0.001) between all groups except Aw/o and EPI200. The vasoactive effect of epinephrine-containing local anaesthetics can be visualised and dynamically quantified via StO2 using HSI. Aw/o + epinephrine 1:100,000 and 1:200,000 leads to perfusion reduction and tissue ischaemia after 30 min, which lasts over 120 min with no significant difference between both formulations. When using Aw/o containing epinephrine in terms of haemostasis for surgical procedures, a prolonged waiting time before incision of 30 or more min can be recommended.

Weekly COVID-19 testing with household quarantine and contact tracing is feasible and would probably end the epidemic.

The COVID-19 epidemic can probably be ended and normal life restored, perhaps quite quickly, by weekly SARS-CoV-2 RNA testing together with household quarantine and systematic contact tracing. Isolated outbreaks could then be contained by contact tracing, supplemented if necessary by temporary local reintroduction of population testing or lockdown. Leading public health experts have recommended that this should be tried in a demonstration project in which a medium-sized city introduces weekly testing and lifts lockdown completely. The idea was not considered by the groups whose predictions have guided UK policy, so we have examined the statistical case for such a study. The combination of regular testing with strict household quarantine, which was not analysed in their models, has remarkable power to reduce transmission to the community from other household members as well as providing earlier diagnosis and facilitating rapid contact tracing.

Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NO x.

The concentration of nitrogen oxides (NO x) plays a central role in controlling air quality. On a global scale, the primary sink of NO x is oxidation to form HNO3. Gas-phase HNO3 photolyses slowly with a lifetime in the troposphere of 10 days or more. However, several recent studies examining HONO chemistry have proposed that particle-phase HNO3 undergoes photolysis 10-300 times more rapidly than gas-phase HNO3. We present here constraints on the rate of particle-phase HNO3 photolysis based on observations of NO x and HNO3 collected over the Yellow Sea during the KORUS-AQ study in summer 2016. The fastest proposed photolysis rates are inconsistent with the observed NO x to HNO3 ratios. Negligible to moderate enhancements of the HNO3 photolysis rate in particles, 1-30 times faster than in the gas phase, are most consistent with the observations. Small or moderate enhancement of particle-phase HNO3 photolysis would not significantly affect the HNO3 budget but could help explain observations of HONO and NO x in highly aged air.

Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets.

Speciated particle-phase organic nitrates (pONs) were quantified using online chemical ionization MS during June and July of 2013 in rural Alabama as part of the Southern Oxidant and Aerosol Study. A large fraction of pONs is highly functionalized, possessing between six and eight oxygen atoms within each carbon number group, and is not the common first generation alkyl nitrates previously reported. Using calibrations for isoprene hydroxynitrates and the measured molecular compositions, we estimate that pONs account for 3% and 8% of total submicrometer organic aerosol mass, on average, during the day and night, respectively. Each of the isoprene- and monoterpenes-derived groups exhibited a strong diel trend consistent with the emission patterns of likely biogenic hydrocarbon precursors. An observationally constrained diel box model can replicate the observed pON assuming that pONs (i) are produced in the gas phase and rapidly establish gas-particle equilibrium and (ii) have a short particle-phase lifetime (∼2-4 h). Such dynamic behavior has significant implications for the production and phase partitioning of pONs, organic aerosol mass, and reactive nitrogen speciation in a forested environment.