Point of Care Ultrasound Bladder Volume Calculation on the Acute Medical Unit.

Nursing staff, healthcare assistants (HCAs) and other healthcare professionals on the Acute Medical Unit (AMU) at Royal Berkshire Hospital (RBH) were taught a Point of Care Ultrasound (POCUS) skill during a twenty minute session. Practitioners learned how to take bladder volume measurements with the Butterfly iQ, a portable ultrasound device which provides a visually-aided method of volume measurement. A Likert scale was used to measure the confidence that staff had in performing volume measurements with the AMU automated scanners, and with the semi-automated Butterfly iQ. After the teaching session, confidence reported by practitioners in using the semi-automated visual method was significantly higher than confidence reported in using the automated non-visual scanners (t < 0.001). Minimal time and expense was required to teach practitioners how to perform this skill. Training nurses in POCUS for bladder visualisation and bladder volume calculation is easy and practicable.

Electromagnetic interference from lasers and intense light sources in the treatment of patients with artificial pacemakers and other implantable cardiac devices.

Measurements of the electric and magnetic field strengths surrounding six laser systems and one intense pulsed light system were carried out. The results were compared to exposure limits published by cardiac device manufacturers to assess the risk of electromagnetic interference to implantable cardiac devices such as pacemakers or implantable cardioverter defibrillators. The majority of lasers assessed in this study were found to produce electric and magnetic field strengths below the published exposure limits for cardiac devices. However, the low-frequency electric field and static magnetic field of both the CO2 laser and the ruby laser were found to exceed these limits. Ensuring that a small separation is maintained at all times between the laser unit and any patient with a pacemaker or implantable cardioverter defibrillator appears to be a sensible expedient in avoiding overexposure of an implantable cardiac device to electromagnetic interference. Due to the single-shot fast discharge nature of the intense pulsed light system, changes in electromagnetic field strength were too fast for some of the measuring equipment used in this study to register accurate readings during operation.

Laser therapy and photosensitive medication: a review of the evidence.

In the 2009 guidelines from the BMLA, the use of non-essential aesthetic lasers was contraindicated in patients receiving medication that causes whole-body photosensitisation as well as those causing local light sensitisation. Following this and anecdotal advice, many laser centres refuse to treat patients who are on known photosensitive medication. Therefore, specific patient cohorts that would benefit from laser therapy are being denied because of medications, such as long-term antibiotics for chronic facial acne. This article reviews the published literature on lasers and photosensitive medications, the mechanisms of photosensitivity and the role of laser in its production. The aim is to analyse the available evidence regarding adverse reactions to laser treatment related to photosensitive medication. A PubMed review of published article titles and abstracts was performed using the search term Laser with each of the following terms individually: photosensitive, photosensitiser, photosensitizer, phototoxicity, photoallergy, complications, case-report, tetracycline, minocycline, amiodarone, nitrofurantoin and medication. Four publications were identified, none of which reported any complication in the use of laser in patients taking photosensitising medication. As there are no published accounts of adverse effects of laser in patients with photosensitive medication, we performed a review of the mechanism of photosensitivity by compiling a list of photosensitive medication and the peak wavelength of radiation required to activate the drug. We recommend a national database of drugs and the wavelengths causing photosensitive reactions of each which a laser department can access prior to treatment.

Finite element analysis of thermal and acoustic processes during laser tattoo removal.

BACKGROUND AND OBJECTIVE: Q-switched laser therapy is commonly used for the removal of tattoos. However, despite ever increasing demand for this intervention, a better understanding of the mechanisms that result in pigment reduction is required in order to optimise outcomes and reduce the number of treatment episodes. STUDY DESIGN: A finite element analysis computer simulation was developed to model the fragmentation response of ink granules during irradiation of a professional black tattoo using a Q-switched Nd:YAG laser. Thermal and acoustic mechanisms were considered, allowing the optimal laser settings to be predicted throughout the course of treatment. Changes in the thermal properties of the ink during heating were taken into account to improve the reliability of the results obtained. RESULTS: The simulated results are in close agreement with clinical observations. Thermal fragmentation was shown to be the dominant mechanism in pigment reduction when using a 6 nanoseconds pulse at 1,064 nm. In order to provide maximum clearance whilst maintaining acceptable levels of tissue thermal damage, later treatments were shown to benefit from higher fluence levels than initial treatments. Larger spot diameters were also preferable throughout the course of treatment. CONCLUSIONS: The results from the simulation build upon previous work carried out in the field, applying ink thermal coefficients which vary with temperature for the first time. These results compliment clinical knowledge, suggesting that a proactive increase in fluence during a course of treatments is likely to improve the response to laser therapy.

Determination of the thermal and physical properties of black tattoo ink using compound analysis.

Despite the widespread use of laser therapy in the removal of tattoos, comparatively little is known about its mechanism of action. There is a need for an improved understanding of the composition and thermal properties of the tattoo ink in order that simulations of laser therapy may be better informed and treatment parameters optimised. Scanning electron microscopy and time-of-flight secondary ion mass spectrometry identified that the relative proportions of the constituent compounds of the ink likely to exist in vivo are the following: carbon black pigment (89 %), carvacrol (5 %), eugenol (2 %), hexenol (3 %) and propylene glycol (1 %). Chemical compound property tables identify that changes in phase of these compounds lead to a considerable reduction in the density and thermal conductivity of the ink and an increase in its specific heat as temperature increases. These temperature-dependent values of density, thermal conductivity and specific heat are substantially different to the constant values, derived from water or graphite at a fixed temperature, which have been applied in the simulations of laser therapy as previously described in the literature. Accordingly, the thermal properties of black tattoo ink described in this study provide valuable information that may be used to improve simulations of tattoo laser therapy.

Simulating light transport through skin for color prediction of port wine stain lesions: a review.

A survey of the literature is presented regarding the simulation of port wine stain (PWS) skin color. Knowledge of PWS features, such as the depths and diameters of affected vessels, is essential for informing laser treatment. These may be determined through the inverse application of a skin model. The techniques which have been applied to achieve this are analyzed in detail. Radiative transfer (RT) is found to be the preferred method of simulation. By far the most common approximations to RT are the diffusion approximations, which have been applied successfully in the past and Monte Carlo techniques, which are now the methods of choice. As the requirements for improvement of laser treatment on an individual basis continues, the needs for further work towards accurate estimations of individual optical coefficients and robust, flexible simulation techniques are identified.

Optical properties of human skin.

A survey of the literature is presented that provides an analysis of the optical properties of human skin, with particular regard to their applications in medicine. Included is a description of the primary interactions of light with skin and how these are commonly estimated using radiative transfer theory (RTT). This is followed by analysis of measured RTT coefficients available in the literature. Orders of magnitude differences are found within published absorption and reduced-scattering coefficients. Causes for these discrepancies are discussed in detail, including contrasts between data acquired in vitro and in vivo. An analysis of the phase functions applied in skin optics, along with the remaining optical coefficients (anisotropy factors and refractive indices) is also included. The survey concludes that further work in the field is necessary to establish a definitive range of realistic coefficients for clinically normal skin.

Adverse effects following Q-switched ruby laser treatment of pigmented lesions.

A retrospective study was conducted to investigate the incidence of adverse effects following Q-switched ruby laser treatment of pigmented lesions at the Wessex Specialist Laser Centre. Sixty-one patients received a total of 151 treatments between January 2006 and January 2008. This is the largest series to date of patients on whom adverse effects have been reported following Q-switched ruby laser treatment of an assortment of pigmented lesions. Patients with traumatic or decorative tattoos were excluded from this study. Two of the treatments (1.3%) resulted in adverse effects. One patient developed hyperpigmentation and the other experienced scabbing and subsequent textural change following abrasion of the scab. No predisposing medical or other factors were observed in either patient. This low incidence of adverse effects is consistent with the highly selective absorption of ruby laser light by melanin. The presence of these adverse effects highlights the importance of test patch treatments, the necessity for patients to follow good post-treatment advice and the case for vigilance in monitoring the quality of the laser output.

Spectrophotometers for the clinical assessment of port-wine stain skin lesions: a review.

Reflectance spectrophotometry is the most established and widely used objective technique for the assessment of port-wine stain (PWS) skin, and has been applied extensively in other dermatological applications. To date, no review has been published regarding the different spectrophotometric devices used on PWS skin. This paper comprises such a review, introducing the reader to the relevant background material and then discussing scanning, narrow-band and tristimulus spectrophotometers in turn. Scanning spectrophotometry is the most versatile of the three methods but it is noted that considerable expertise is required to interpret the acquired data. Narrow-band and tristimulus devices are available at a much lower price and can be considerably simpler to use. They do, however, provide limited information that does not account for the complex effects of melanin and other chromophores within the skin. Although scanning spectrophotometers would be the preferred choice for most investigations, cheaper, simpler and equally reliable options are available and may better suit the needs of some research projects.