Background/Objectives: Septic shock involves severe circulatory and microcirculatory dysfunction and often requires vasopressors to maintain adequate mean arterial pressure (MAP). Conventional monitoring mainly reflects macrocirculation and may not capture changes in vascular tone or microcirculation. Remote photoplethysmography (rPPG) is a contactless optical method that analyzes peripheral pulse waveforms and may offer additional physiological insight during vasopressor therapy. The aim of this study was to assess the feasibility of rPPG for detecting pulse waveform changes associated with norepinephrine administration in septic shock. Methods: Prospective case series included three adult patients (n = 3) with septic shock admitted to the intensive care unit at Pauls Stradins Clinical University Hospital, Riga, Latvia. All patients received standard sepsis treatment, including fluid resuscitation and titrated norepinephrine to maintain MAP ≥ 65 mmHg. Continuous invasive arterial pressure monitoring was performed alongside rPPG signal acquisition from the palmar skin surface under controlled lighting. From averaged rPPG waveforms, perfusion index (PI), dicrotic notch amplitude (c-wave), and diastolic wave amplitude (d-wave) were extracted. Correlations between norepinephrine dose, MAP, and rPPG parameters were explored. Results: Increasing norepinephrine doses were associated with higher MAP and PI in all patients. Dicrotic notch and diastolic wave amplitude decreased consistently. These changes occurred alongside macrocirculatory stabilization and are consistent with increased vascular tone and altered arterial compliance. Conclusions: rPPG demonstrated feasibility for detecting pulse waveform changes during norepinephrine therapy in septic shock; however, larger controlled studies are required for validation.

Background and Objectives: Septic shock is marked by profound circulatory and cellular dysfunction, with mortality rates of 25–40% despite guideline-based resuscitation. Normalization of macrohemodynamic variables often fails to restore tissue perfusion, a concept known as hemodynamic incoherence. Persistent microcirculatory dysfunction is associated with organ failure and poor outcomes, underscoring the limitations of systemic monitoring alone. This focused narrative review synthesizes current evidence on microcirculatory monitoring in septic shock, with emphasis on bedside and emerging optical technologies, and evaluates their role as adjuncts to traditional hemodynamic assessment for perfusion-targeted resuscitation. Materials and Methods: A concept-driven search of PubMed/MEDLINE (January 2015 to January 2026) was performed, incorporating MeSH and free-text terms for septic shock, microcirculation, hemodynamic coherence, and monitoring modalities. Foundational pre-2015 studies were included for context. Articles were screened using predefined inclusion/exclusion criteria to minimize bias, with thematic qualitative synthesis. A PRISMA-inspired flow diagram was used to summarize the study selection process. Results: Microcirculatory alterations in septic shock include reduced functional capillary density, perfusion heterogeneity, and impaired oxygen extraction, persisting despite macrohemodynamic correction. Bedside markers, such as capillary refill time (CRT) and mottling, track microvascular recovery more closely than lactate. When used to guide resuscitation, CRT-based strategies show a non-significant mortality trend in randomized evaluation, with later studies reporting benefit in composite clinical outcomes. Optical technologies offer non-invasive insights: photoplethysmography (PPG) and perfusion index (PI) show prognostic value and early detection of incoherence; automated CRT (aCRT) enhances reproducibility; advanced modalities, such as laser speckle contrast imaging (LSCI), near-infrared spectroscopy (NIRS), and sublingual videomicroscopy, provide detailed physiological data but face standardization challenges. Recent interventional evidence, including peripheral perfusion-targeted RCTs, supports improved outcomes, though large-scale trials remain limited. Conclusions: Microcirculatory monitoring provides complementary, physiologically relevant information to macrohemodynamic assessment in septic shock. Emerging bedside tools, such as PI and aCRT, are poised for routine use, while multimodal integration may enable personalized management. Future research should prioritize standardization, AI-driven analysis, and randomized trials to confirm outcome benefits.

This invited paper reviews recent results achieved by snapshot triple wavelength imaging of skin, a method ensuring high spectral and spatial resolution within sub-second imaging time, avoiding motion artefacts in the spectral image sets. Designs of the developed diagnostic equipment and the related image processing solutions are discussed along with outcomes of their clinical validation on volunteers with various skin malformations, including cancers. The initial contact technology for single skin lesion spectral imaging in the visible range has been extended to remote full body or large area multi-lesion image acquisition and analysis, including also near-infrared skin images. The potential of triple wavelength imaging for implementation in routine dermatological practice is discussed.

To ensure high spectral selectivity of whole-body skin diagnostics and early cancer screening, a prototype device for skin multispectral imaging at narrow 450/520/638/850/940 nm spectral bands has been developed and clinically validated. Skin images were captured by a high-resolution color camera with removed infrared cut-off filter under spectrally specific multi-laser or 940 nm LED illumination. The camera, surrounded by two side-emitting optical fiber spirals coupled with visible RGB laser and 850 nm near-infrared laser, could be moved up and down, while imaging of any diseased skin area was ensured by positioning the patient in front of camera. The system was clinically validated in Oncology Center of Latvia on 60 patients diagnosed with basal cell carcinoma, malignant melanoma or skin lesions suspected of malignancy. Analysis of clinical data confirmed promising potential of NIR imaging for skin cancer detection and screening. Details of the equipment design and image analysis procedure, as well as the results of patient measurements are presented.

Background: Peripheral nerve blocks in regional anesthesia are operator-dependent and are not always successful, leading to patient discomfort and postoperative pain. Current methods for assessing block failure rely on subjective patient reports of sensory and motor loss, which take time to appear and can be misleading. This study evaluates thermography as an objective, quantitative method for determining nerve block success and discusses its practical implications for clinical practice. Methods: This study was conducted at the Hospital of Traumatology and Orthopedics in Riga and included 55 patients undergoing sciatic nerve block with equipotent doses of different local anesthetics. Three local anesthetics—lidocaine, bupivacaine, and ropivacaine—were used in equipotent doses. After the block, the anesthetized region was imaged with a thermographic camera for 45 min to detect temperature changes. Results: Analysis showed no clinically significant differences among the local anesthetics in the timing or magnitude of skin temperature changes. At least 15 min must elapse before using thermography to judge nerve block success. Thermography is less reliable in acute bone fractures. Additionally, lower initial skin temperature was associated with a faster observable temperature increase, proving a strong negative correlation.

This study applies Monte Carlo simulation to model the spectral images of skin lesions in the visible and near-infrared ranges. By simulating the spatial distribution of backscattered light, we analyze the correlation between its optical properties and spectral features.

This study examines remote photoplethysmography (rPPG) waveform changes during the Passive Leg Raising Test to assess fluid responsiveness non-invasively. Results suggest rPPG-derived reflection index (RI) correlates with hemodynamic changes, offering a potential alternative to invasive monitoring. (c) 2025 The Author(s)

Spectral imaging - acquisition of images within specific spectral intervals - is a powerful tool for optical diagnostics, able to provide objective data on various clinical parameters, e.g. abnormal content of biomolecules in pathologic tissues. Performance of diagnostics depends on the spectral selectivity of imaging; from this point, ultra-narrowband spectral line imaging appears well-suited for diagnostic applications. Two prototype devices for triple laser line imaging have been developed and tested in laboratory and clinical environments. Large area or whole-body skin spectral imaging device comprises vertically movable high-resolution camera coupled with a specific illumination unit - side-emitting optical fiber spiral that emits simultaneously three laser spectral lines at the wavelengths 450 nm, 520 nm and 628 nm. In the other device, conventional white broadband endoscopic illumination has been replaced by a combined three spectral line white illumination from a low power RGB laser-fiber system attached to the lighting channel of intranasal endoscope. Both prototypes undergo clinical validation; their design details and preliminary test results are reported and discussed.

Multispectral imaging can provide objective quantitative data on various clinical pathologies, e.g., abnormal content of bio-substances in human skin. Performance of diagnostics increases with decreased spectral bandwidths of imaging; from this point, ultra-narrowband laser spectral line imaging is well suited for diagnostic applications. In this study, 40 volunteers participated in clinical validation tests of a newly developed prototype device for triple laser line whole-body skin imaging. The device comprised a vertically movable high-resolution camera coupled with a specific illumination unit—a side-emitting optical fiber spiral that emits simultaneously three RGB laser spectral lines at the wavelengths 450 nm, 520 nm, and 628 nm. The prototype’s design details, skin spectral image processing, and the obtained first clinical data are reported and discussed.

Background and Objectives: Sepsis, a leading global health challenge, accounts for around 20% of deaths worldwide. The complexity of sepsis, especially the difference between bacterial and viral etiologies, requires an effective assessment of microcirculation during resuscitation. This study aimed to evaluate the impact of infusion therapy on microcirculation in patients with sepsis, focusing on bacterial- and COVID-19-associated sepsis using remote photoplethysmography (rPPG) and the automated capillary refill time (aCRT). Materials and Methods: This single-center prospective study was conducted in the ICU of Pauls Stradins Clinical University Hospital, including 20 patients with sepsis/septic shock. The patients were selected based on hemodynamic instability and divided into COVID-19 and Bacterial Septic Shock groups. Fluid responsiveness was assessed using the Passive Leg Raising Test (PLRT). Systemic hemodynamics and microcirculation were monitored through MAP CRT, rPPG, and serum lactate levels. Statistical analyses compared responses within and between the groups across different stages of the protocol. Results: The Bacterial group exhibited higher initial serum lactate levels and more pronounced microcirculatory dysfunction than the COVID-19 group. rPPG was more sensitive in detecting perfusion changes, showing significant differences between the groups. The automated CRT demonstrated greater sensitivity compared to the manual CRT, revealing significant differences during PLRT stages between bacterial- and COVID-19-associated sepsis. Both groups had a transient hemodynamic response to PLRT, with subsequent stabilization upon fluid infusion. Conclusions: When managing patients with sepsis in intensive care, monitoring microcirculation is of paramount importance in infusion therapy. Our study highlights the potential of rPPG and aCRT as tools for this purpose. These techniques can be used in conjunction with routine parameters, such as lactate levels and systemic hemodynamic parameters, to provide a comprehensive assessment of a patient’s condition.

Abstract Diseases of the nasal mucosa are common in clinical practice; on average, every third ENT (ear, nose, throat) patient complains of nasal mucosa problems. Mucosa pathologies change the structure and composition of tissue; the presence of different cells, variation in biochemical composition and dilation or constriction of blood vessels lead to mucosa colour changes that help setting the diagnosis. However, experience and colour vision vary between doctors, so a more objective mucosa colour examination could be helpful. The aim of this study was to investigate whether colour analysis of camera-captured endoscopic images can distinguish healthy from pathological nasal mucosa and how specific such analysis could be for various diseases. A total of 66 participants (four groups, including healthy volunteers) underwent anterior nasal endoscopy, and the taken photos and videos were further analysed using self-developed Matlab software. The procedure involved selection of the region of interest (inferior nasal turbinate), segmentation and averaging the colour parameters over selected areas, exploiting the RGB and L * a * b colour scales. Allergic, chronic hyperplastic and inflamed (chronic and acute) nasal mucosa conditions in comparison with healthy mucosa were studied in this work. A relatively wide spread of colour parameter values was observed in the healthy volunteer group as well as in all patient groups. The most sensitive colour parameters for each of the pathology groups were identified.

The origin of blood pulse waveform is mainly affected by various factors, such as vascular age, lifestyle, and ability of vascular disorders. Non-contact optical measurements of blood volume pulse in microvascular tissue were performed by remote photoplethysmography. This work aims to classify subjects into a specific vascular health condition based on a given pulse waveform using network-based machine learning models. For this reason, we trained our models by 9000 waveforms taken from palm’s dorsal side of 18 subjects (14 healthy, age 21-54 yrs. and 4 patients affected by septic shock and taking vasopressors, aged 45-81 yrs.). To get variant waveforms, we employed a bilateral thigh supra-systolic occlusion test in healthy subjects to temporarily compromise leg blood supply, potentially altering vascular resistance. To train and validate our models we used five relevant hemodynamic parameters which are related to reflected waves from the periphery. The classification model validation tests showed the following best accuracy taken from five classes: true-positive 98.8 % and false-negative 1.2%. The neural network-based approach could be valuable for prediction of vascular health state from blood pulse waveform in cases when the signal is weak and noisy.

Occlusion in limbs, arising from conditions like peripheral arterial disease or certain postures, significantly affects blood flow and vascular health. Our study examined the impact of bilateral thigh occlusion on systemic and local hemodynamics using remote photoplethysmography (PPG) waveform in 18 healthy subjects. By employing a supra-systolic occlusion protocol, we assessed changes in heart rate (HR), mean arterial pressure (MAP), and total peripheral resistance (TPR), along with PPG signal alterations at 540 nm. Results showed that occlusion led to temporary fluctuations in MAP, HR, and TPR, followed by notable increases in these parameters and the PPG waveform parameter RI. Post-occlusion, we observed substantial declines in MAP, TPR, and RI. These findings underline the significance of thigh occlusion in altering systemic hemodynamics and suggest the potential of palmar PPG in evaluating vascular resistance. However, the complex relationship between central hemodynamics and local cutaneous microcirculation responses, influencing the PPG signal, require further research.

Sepsis is a life-threatening organ dysfunction caused by dysregulation of host response to infection (e.g. bacterial, viruses etc.).1 Sepsis can cause septic shock with reduction of microcirculation. Assessments of microcirculation during fluid resuscitation mostly rely on serum lactate level and manual capillary refill time. New techniques for evaluation of microcirculation monitoring have been developed—remote photoplethysmography (rPPG) and automated objective capillary refill time measurement technique (aCRT).

Spectral imaging – acquisition of images at specific spectral intervals - is a powerful tool for optical diagnostics, providing objective quantitative data on various clinical parameters, e.g. abnormal content and distribution of chromophores in pathologic tissues. The narrower are spectral bands of imaging, the better is performance of diagnostics; from this point, triple laser line illumination has a potential to ensure excellent spectral selectivity of imaging. This study aims at development and validation of RGB laser-fiber based technologies for high performance spectral imaging of skin and mucosa malformations. Our previous knowledge on skin malformation's spectral line imaging is extended to the whole-body spectral imaging and endoscopic narrowband imaging of mucosa. Design features of two demo-setups ensuring simultaneous illumination of the target tissues by laser lines 450 nm, 520 nm and 638 nm are discussed. Results of laboratory measurements confirm applicability of RGB laser line spectral imaging technology for improved optical diagnostics in dermatology and endoscopy.