On the detection of peripheral cyanosis in individuals with distinct levels of cutaneous pigmentation

Development and validation of a case study to aid in the diagnostic reasoning of nursing students and nurses

PURPOSE

The aim of this study is to develop and validate a case study to aid in the diagnostic reasoning of nursing students and nurses.

METHODS

It is a validation study using a case study based on Lunney's method including (1) content validation of the case study by nurse experts through the Delphi technique, (2) identification of nursing diagnoses (NDs) in the case, (3) evaluation of diagnostic accuracy, and (4) establishment of a priority diagnosis by nurse experts.

FINDINGS

The case study was developed from the findings of a narrative literature review on the cues of the NDs with a prevalence > 50% in patients with peripheral arterial occlusive disease. Two rounds of expert evaluation were required to validate the case study. The experts identified 18 NDs with different degrees of accuracy. The highly accurate diagnoses most frequently identified by the experts were: Ineffective peripheral tissue perfusion (100%), impaired walking (83%), impaired comfort (50%), and chronic pain (50%). The diagnosis considered a priority by all experts was ineffective peripheral tissue perfusion.

CONCLUSIONS

The case study was developed and had its content validated. High-accuracy diagnoses were identified, and a priority was determined.

IMPLICATIONS FOR NURSING PRACTICE

The validated case study may be used by students and nurses to facilitate the development of diagnostic reasoning and critical thinking in practice, teaching or research.

In Silico Assessment of Tanning Masking Effects on Skin Chromatic Attributes Elicited by Anemia and Hyperbilirubinemia

Changes in skin appearance are among the most recognizable symptoms of a number of medical conditions. The interpretation of such changes, however, may be inadvertently biased by normal physiological processes affecting skin optical properties. In this paper, we assess the impact of one of the most common of these processes, tanning, on variations in skin chromatic attributes elicited by two ubiquitous and serious medical conditions, anemia and hyperbilirubinemia. We employ a first-principles investigation approach centered on the use of predictive computer simulations of light and skin interactions, and on well-established colorimetry methods. In our in silico experiments, we considered skin chromatic attributes resulting from distinct anemia severity levels and hyperbilirubinemia tox-icity stages. Our findings highlight qualitative and quantitative aspects that need to be considered in the visual screening and monitoring of these conditions, notably when they occur with the concomitant presence of tanning-induced changes in the cutaneous tissues' melanin pigmentation and thickness.

Tanning-Elicited Variations in the Ultraviolet Absorption Spectra of the Cutaneous Tissues: Skin Photobiology and Photomedicine Implications

When ultraviolet radiation is absorbed within the cutaneous tissues, it can trigger a number of phenomena that can have detrimental or beneficial consequences to an individual's health. Tanning is among the most visually noticeable of these phenomena. It may result in significant changes in skin pigmentation and thickness. These spectrally-dependent physiological responses, in turn, can elicit variations in the ultraviolet absorption profiles of the cutaneous tissues and, consequently, alter the occurrence of other ultraviolet-induced photobiological processes such as the breaking of DNA strands and the synthesis of previtamin D3. These tanning-elicited variations in the cutaneous tissues' absorption profiles is often tied to the increased presence of melanin throughout these tissues. However, during the tanning, shifts in the relative content of this pigment within certain skin layers can also be observed. In particular, the stratum basale, the innermost epidermal layer where melanogenesis takes place, can have its relative melanin content significantly reduced in comparison with other epidermal layers. Since the aforementioned photobiological phenomena are preferentially brought about within this layer, such pigmentation shifts may have a more pivotal role in skin photobiology than has been assumed to date. Accordingly, in this work, we investigate the impact of spectrally-dependent tanning-elicited physiological responses, with a particular focus on the inter-layer melanin distribution patterns, on the absorption profiles of the main cutaneous tissues. We also examine how variations in these absorption profiles may alter the outcomes of photo-triggered phenomena associated with the onset of different medical conditions. Our findings are expected to contribute to the advance of the current understanding about skin photobiology, which is indispensable for the success of photomedicine initiatives involving this highly complex organ.

On the Sensitivity of Skin Spectral Responses to Variations in the Thickness of the Cutaneous Tissues

A wide range of devices are being routinely used in the noninvasive screening and monitoring of medical conditions through the analysis of skin spectral responses. The correct interpretation of these responses often depends on the availability of high-fidelity characterization datasets for the selected specimens. More specifically, the higher their fidelity, the more effective the quantification of changes observed in a given biophysical variable of interest. Skin thickness is among the most relevant of these parameters since it plays a pivotal role in the attenuation (scattering and absorption) of light traversing the cutaneous tissues. Transient and permanent physiological processes, such as tanning and ageing, can result in significant time-dependent thickness variations. These, in turn, can introduce biases in the comparison of skin spectral responses obtained at different time instances. In this paper, we investigate the impact of thickness variations on skin reflectance with respect to different regions of light spectrum. Our findings are expected to contribute to the mitigation of interpretation errors and, thus, to the enhancement of noninvasive screening and monitoring procedures based on skin spectral responses.

On the Effective Differentiation and Monitoring of Variable Degrees of Hyperbilirubinemia Severity Through Noninvasive Screening Protocols

The presence of abnormal amounts of bilirubin in the blood stream and skin, usually referred to as hyperbilirubinemia, is associated with a wide range of pathologies that can pose considerable risks for human health. The early and effective screening of the severity degrees of this medical condition can play an important role on the selection of the appropriate treatment for the associated pathologies. This, in turn, can minimize the need for more aggressive and costly therapeutic interventions which can themselves pose considerable risks for morbidity and mortality. The current noninvasive protocols used to differentiate these severity degrees, however, are hindered by the relatively limited knowledge about the impact of different amounts of extravascular bilirubin on skin spectral responses and on the onset of jaundice, the resulting yellow-tinted skin appearance. In this paper, we address this open problem through controlled in silico experiments supported by measured data provided in the related literature. Our experimental findings bring biophysically-based insights to bear on the clarification of this biomedical entanglement, and unveil optical features that can potentially lead to more effective screening protocols for the noninvasive differentiation and monitoring of variable degrees of hyperbilirubinemia severity.

Unveiling the Impact of Distinct Melanosome Arrangements on the Attenuation of Cancer-Inducing Ultraviolet Radiation

The exposure of human skin to ultraviolet radiation (UVR) can trigger a wide array of biological responses, including photocarcinogenesis. Melanin, either in colloidal form or encapsulated into melanosomes, is known to be the main UVR attenuation substance acting within the cutaneous tissues. Although many studies have addressed the protective role of this pigment against the harmful effects of UVR exposure, the impact of different melanosome arrangements on the mitigation of these effects remains to be quantitatively verified. The difficulties to resolve this open question can be mainly attributed to the intrinsic practical limitations of in vivo and in vitro experiments involving skin specimens. In this paper, we describe controlled in silico experiments that allowed us to overcome such limitations and provide quantitative evidence for the clarification of this question. Besides contributing to a more robust understanding of the physiological parameters associated with cutaneous UVR attenuation, our findings can be incorporated into the development of more effective strategies for the evaluation of individuals' susceptibility to UVR exposure. Such strategies are essential for the prevention of UVR-induced pathologies, particularly skin cancer.

Elucidating the contribution of Rayleigh scattering to the bluish appearance of veins

The bluish appearance of veins located immediately beneath the skin has long been a topic of interest for biomedical optics researchers. Despite this interest, a thorough identification of the specific optical processes responsible for this phenomenon remains to be achieved. We employ controlled in silico experiments to address this enduring open problem. Our experiments, which are supported by measured data available in the scientific literature, are performed using first-principles models of light interaction with human skin and blood. Using this investigation approach, we quantitatively demonstrate that Rayleigh scattering caused by collagen fibrils present in the papillary dermis, a sublayer of the skin, can play a pivotal role in the bluish appearance of veins as suggested by previous works in this area. Moreover, also taking color perception aspects into account, we systematically assess the effects of variations in fibril radius and papillary dermis thickness on the coloration of veins under different illuminants. Notably, this assessment indicates that Rayleigh scattering elicited by reticulin fibrils, another type of fibril found in the papillary dermis, is unlikely to significantly contribute to the bluish appearance of veins. By strengthening the current understanding of light attenuation mechanisms affecting the appearance of skin and blood, our investigation contributes to the development of more effective technologies aimed at the noninvasive measurement of the physiological properties of these tissues.