Evaluation of serial application of capillaroscopy, photoplethysmography, and dermothermometry in diagnosis and prevention of radiolesions of peripheral microvessels

Nailfold Capillaroscopic Findings in an Orthopedic Surgeon: Reversible Abnormalities after the Cessation of Radiation Exposure

Interventional fluoroscopy is a leading source of occupational ionizing radiation exposure for medical personnel. For example, orthopedic surgeons represent one occupation where the risk of exposure is large. This occupational hazard is the result of a cumulative dose of radiation over time. Adverse health effects induced by low-dose radiation exposure can arise from daily procedures performed over an entire career. Many of the radiation-induced effects that may develop are transient erythema, permanent epilation, dry desquamation, dermal necrosis and telangiectasia; these effects have occurred on the skin of fingers of interventionalists. Nailfold videocapillaroscopy (NVC) is a non-invasive technique useful for early detection of radiation-induced effects on microcirculation of fingernails. Here we report on a case of an orthopedic surgeon exposed to radiation for 30 years during his professional career. He performed NVC before and after the end of his professional career, and regression of the microcirculatory abnormalities were documented after cessation of radiation exposure. To our knowledge, this is the first published work in which the regression of chronic low-dose radiation-induced alterations of finger microvessels have been described and documented.

Effects of chronic low-dose exposure to ionizing radiation on physician microvascular structure revealed by nail fold capillaroscopy

The aim of this study was to assess the long-term asymptomatic effects of low-dose radiation on microvascular structure among interventional physicians, whose hands are exposed to ionizing radiation during daily practice. The study, approved by the national ethics committee, included 186 radiation-exposed (surgeons, cardiologists, radiologists) and 35 unexposed physicians, all of whom had provided written consent. The subjects completed a questionnaire describing their current and past daily practice, from which tentative estimates of current and cumulative radiation exposure estimates were computed. Subject dermal microcirculation state was assessed by capillaroscopy of the nail fold of eight fingers (thumbs excluded) based on photographs. Two quantitative scores characterizing extravasation and morphological abnormalities based on seven semiquantitative indices were obtained from post hoc coding of the photographs by five capillaroscopists. These evaluations were randomized and blind to the exposure. The effect of the radiation exposure on both abnormality scores was modelled using multilevel proportional odds regression adjusted for potential confounders. The proportion of physicians for which the most frequent act is close to the radiation source was highest among surgeons, but with fewer weekly acts. The median duration of exposure was highest among radiologists and cardiologists. No exposure effect could be detected on the extravasation score. The morphological anomaly score increased significantly with duration of exposure and estimated cumulative exposure among surgeons and interventional radiologists, unlike cardiologists among whom no effect could be detected. It is concluded that the shown effects of chronic low-dose exposure to ionizing radiation on physician microvascular structure reveal the importance of increased exposure monitoring and prevention.

Management of Ionizing Radiation Injuries and Illnesses, Part 5: Local Radiation Injury

This final article in the series on the medical management of ionizing radiation injuries and illnesses focuses on the effects of acute ionizing radiation exposure to one of the largest organ systems of the body—the skin. These injuries may extend beyond the skin into deeper tissues and cause local radiation injury. There are numerous causes of these injuries, ranging from industrial incidents to medical procedures. In the present article, the authors characterize the clinical course, pathophysiologic process, sources of injury, diagnosis, and management of local radiation injury and describe a clinical scenario. This information is important for primary care physicians, to whom patients are likely to initially present with such injuries. J Am Osteopath Assoc. 2014;114(11):840-848 doi: 10.7556/jaoa.2014.170

Photoplethysmography and its application in clinical physiological measurement

Photoplethysmography (PPG) is a simple and low-cost optical technique that can be used to detect blood volume changes in the microvascular bed of tissue. It is often used non-invasively to make measurements at the skin surface. The PPG waveform comprises a pulsatile ('AC') physiological waveform attributed to cardiac synchronous changes in the blood volume with each heart beat, and is superimposed on a slowly varying ('DC') baseline with various lower frequency components attributed to respiration, sympathetic nervous system activity and thermoregulation. Although the origins of the components of the PPG signal are not fully understood, it is generally accepted that they can provide valuable information about the cardiovascular system. There has been a resurgence of interest in the technique in recent years, driven by the demand for low cost, simple and portable technology for the primary care and community based clinical settings, the wide availability of low cost and small semiconductor components, and the advancement of computer-based pulse wave analysis techniques. The PPG technology has been used in a wide range of commercially available medical devices for measuring oxygen saturation, blood pressure and cardiac output, assessing autonomic function and also detecting peripheral vascular disease. The introductory sections of the topical review describe the basic principle of operation and interaction of light with tissue, early and recent history of PPG, instrumentation, measurement protocol, and pulse wave analysis. The review then focuses on the applications of PPG in clinical physiological measurements, including clinical physiological monitoring, vascular assessment and autonomic function.

Capillary blood flow during severe hemodilution observed by a noninvasive transcutaneous technique using flash epi-illumination

Capillary red blood cell (RBC) flow in the skin of rat tail during an extreme hemodilution with albumin was microscopically observed with a completely noninvasive transcutaneous technique using flash epi-illumination. This illumination with a filter (center wavelength, 550 nm) caused RBC to become darker and contrast well with the background tissue since the light was absorbed by hemoglobin inside the RBC. The recorded videotape showed a clear image of RBC without tailing because of flash (strobe light) illumination, and this allowed accurate analysis of the RBC flow rate and capillary hematocrit. During hemodilution up to a 50% level of blood exchange, the functional capillary density remained unchanged and it started to decline significantly at the 60% level of blood exchange and reached 37 +/- 32% of the basal value at the 80% level of blood exchange. The RBC flow rates monotonously increased up to 294 +/- 110% of the basal value at the 60% level of blood exchange, which was in contrast to the abdominal aortic blood flow increase to 148 +/- 20%. Capillary hematocrit did not appear to fall in the same proportion as the systemic hematocrit, which coincided with the previous observations. These results indicate that microhemodynamic properties during hemodilution can be transcutaneously analyzed with this new technique without surgical preparation of the skin.

[Evaluation of late radiation-induced changes in superficial microcirculation after acute beta-irradiation. II. Prognostic importance of cutaneous Doppler laser]

OBJECTIVE

The changes that occur in the tissular microcirculation after accidental acute irradiation account for some of the early effects of such irradiation, especially at the cutaneous level. The prognostic importance of the cutaneous laser doppler was tested in an experimental model of acute beta-irradiation.

METHODS

Ten pigs were given beta-irradiation with a high single localized dose of 90Sr/90Y (32 or 64 Gy, 7 mg/cm2) delivered to the flank, and were evaluated 2, 7, 14, 21 and 28 days thereafter. Each individual was its own control. The local microcirculation was measured in the resting state and during thermal stimulation at 42 degrees C, using a Periflux cutaneous Doppler laser with p413 probes. Three periods of six minutes each were continuously recorded: period 1 (P1) represented basal resting cutaneous perfusion, with the slope p corresponding to the increase in perfusion when two minutes of thermal stimulation at 42 degrees C began; P2 to plateau perfusion during this stimulation; and P3 to perfusion on the return to equilibrium.

RESULTS

After acute beta-irradiation in the pig, all the cutaneous microcirculation parameters measured (P1, p, P2 and P3) had risen at day 2 in the irradiated area by a factor of 2 to 4, depending on the dose (p < 0.001), compared to the adjacent control area. On the other hand, as from day 7, the resting and the stimulated microcirculation varied little, except for a reduction of the slope p by a factor of 2 (p < 0.05) after the strongest radiation dose.

CONCLUSION

After acute irradiation, the increase in the resting cutaneous microcirculation may correspond to immediate but transitory capillary vasodilatation that accompanies the initial erythema in accidental irradiation. The absence of vascular response to thermal stimulation seems to be a good means of reaching an early diagnosis of delayed cutaneous radiation necrosis.