We would like to extend our gratitude to the Link&#246;ping staff of The Swedish Defense Agency (FOI) and the Center for disaster medicine and Traumatology (KMC) for their kind support.

The study described here followed the local ethic guidelines and was approved by the regional ethical review board in Link&#246;ping (permit number 2015/99-31).
1. Informed Consent and Screening
<ol>
	<li>Obtain informed consent from the subject.</li>
	<li>Screen according to inclusion/exclusion criteria. 
	NOTE: Inclusion criteria were: (i) Healthy adult &#62;18 years of age, (ii) Able to understand written and oral information, and (iii) Provides oral and written consent. Exclusion cr...

<ol>
	<li>Strehlow, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+identification+of+shock+in+critically+ill+patients.">Early identification of shock in critically ill patients.</a> Emerg Med Clin North Am. 28 (1), 57-66 (2010).</li><li>Advanced Life Support, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Acute Medical Emergencies. , 67-84 (2010).</li><li>Brasel, K. J., Guse, C., Gentilello, L. M., Nirula, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+rate:+is+it+truly+a+vital+sign?.">Heart rate: is it truly a vital sign?.</a> J Trauma. 62 (4), 812-817 (2007).</li><li>De Backer, D., Ortiz, J. A., Salgado, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coupling+microcirculation+to+systemic+hemodynamics.">Coupling microcirculation to systemic hemodynamics.</a> Curr Opin Crit Care. 16 (3), 250-254 (2010).</li><li>Mrgan, M., Rytter, D., Brabrand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+refill+time+is+a+predictor+of+short-term+mortality+for+adult+patients+admitted+to+a+medical+department:+an+observational+cohort+study.">Capillary refill time is a predictor of short-term mortality for adult patients admitted to a medical department: an observational cohort study.</a> Emerg Med J. 31 (12), 954-958 (2014).</li><li>Advanced Life Support, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Acute Medical Emergencies. , 55-65 (2010).</li><li>Lewin, J., Maconochie, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+refill+time+in+adults.">Capillary refill time in adults.</a> Emerg Med J. 25 (6), 325-326 (2008).</li><li>Lobos, A. T., Menon, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multidisciplinary+survey+on+capillary+refill+time:+Inconsistent+performance+and+interpretation+of+a+common+clinical+test.">A multidisciplinary survey on capillary refill time: Inconsistent performance and interpretation of a common clinical test.</a> Pediatr Crit Care Med. 9 (4), 386-391 (2008).</li><li>Otieno, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Are+bedside+features+of+shock+reproducible+between+different+observers?.">Are bedside features of shock reproducible between different observers?.</a> Arch Dis Child. 89 (10), 977-979 (2004).</li><li>Raju, N. V., Maisels, M. J., Kring, E., Schwarz-Warner, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+refill+time+in+the+hands+and+feet+of+normal+newborn+infants.">Capillary refill time in the hands and feet of normal newborn infants.</a> Clin Pediatr (Phila). 38 (3), 139-144 (1999).</li><li>Klupp, N. L., Keenan, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+evaluation+of+the+reliability+and+validity+of+capillary+refill+time+test.">An evaluation of the reliability and validity of capillary refill time test.</a> The Foot. 17, 15-20 (2007).</li><li>Gorelick, M. H., Shaw, K. N., Baker, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+ambient+temperature+on+capillary+refill+in+healthy+children.">Effect of ambient temperature on capillary refill in healthy children.</a> Pediatrics. 92 (5), 699-702 (1993).</li><li>Schriger, D. L., Baraff, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defining+normal+capillary+refill:+variation+with+age,+sex,+and+temperature.">Defining normal capillary refill: variation with age, sex, and temperature.</a> Ann Emerg Med. 17 (9), 932-935 (1988).</li><li>Pandey, A., John, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+refill+time.+Is+it+time+to+fill+the+gaps?.">Capillary refill time. Is it time to fill the gaps?.</a> Med J Armed Forces India. 69 (1), 97-98 (2013).</li><li>Strozik, K. S., Pieper, C. H., Roller, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+refilling+time+in+newborn+babies:+normal+values.">Capillary refilling time in newborn babies: normal values.</a> Arch Dis Child Fetal Neonatal Ed. 76 (3), F193-F196 (1997).</li><li>Doherty, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sub-epidermal+imaging+using+polarized+light+spectroscopy+for+assessment+of+skin+microcirculation.">Sub-epidermal imaging using polarized light spectroscopy for assessment of skin microcirculation.</a> Skin Res Technol. 13 (4), 472-484 (2007).</li><li>Noguchi, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+caffeine+contained+in+a+cup+of+coffee+on+microvascular+function+in+healthy+subjects.">Effect of caffeine contained in a cup of coffee on microvascular function in healthy subjects.</a> J Pharmacol Sci. 127 (2), 217-222 (2015).</li><li>Reus, W. F., Robson, M. C., Zachary, L., Heggers, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+effects+of+tobacco+smoking+on+blood+flow+in+the+cutaneous+micro-circulation.">Acute effects of tobacco smoking on blood flow in the cutaneous micro-circulation.</a> Br J Plast Surg. 37 (2), 213-215 (1984).</li><li>Lenasi, H., Strucl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+regular+physical+training+on+cutaneous+microvascular+reactivity.">Effect of regular physical training on cutaneous microvascular reactivity.</a> Med Sci Sports Exerc. 36 (4), 606-612 (2004).</li><li>Anderson, B., Kelly, A. M., Kerr, D., Clooney, M., Jolley, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+patient+and+environmental+factors+on+capillary+refill+time+in+adults.">Impact of patient and environmental factors on capillary refill time in adults.</a> Am J Emerg Med. 26 (1), 62-65 (2008).</li><li>John, R. T., Henricson, J., Nilsson, G. E., Wilhelms, D., Anderson, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reflectance+spectroscopy:+to+shed+new+light+on+the+capillary+refill+test.">Reflectance spectroscopy: to shed new light on the capillary refill test.</a> J Biophotonics. , (2017).</li><li>Blaxter, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+automated+quasi-continuous+capillary+refill+timing+device.">An automated quasi-continuous capillary refill timing device.</a> Physiological measurement. 37, 83-99 (2016).</li><li>Bordoley, A., Irwin, R., Kalyani, V., MacDonald, C., Standish, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> D1GIT: Automated, temperature-calibrated measurement of capillary refill time. , (2012).</li><li>Kviesis-Kipge, E., Curkste, E., Spigulis, J., Eihvalde, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+analysis+of+skin+capillary-refill+processes+using+blue+LED.">Real-time analysis of skin capillary-refill processes using blue LED.</a> Proc. of SPIE. 771523, (2010).</li><li>Shavit, I., Brant, R., Nijssen-Jordan, C., Galbraith, R., Johnson, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+imaging+technique+to+measure+capillary-refill+time:+improving+diagnostic+accuracy+for+dehydration+in+young+children+with+gastroenteritis.">A novel imaging technique to measure capillary-refill time: improving diagnostic accuracy for dehydration in young children with gastroenteritis.</a> Pediatrics. 118 (6), 2402-2408 (2006).</li><li>Cohen, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitor+to+Measure+Dermal+Blood+Flow+in+Critically+Ill+Patients:+Study.">Monitor to Measure Dermal Blood Flow in Critically Ill Patients: Study.</a> International Scholarly Research Notices. 578316, e578316 (2013).</li></ol>

No financial support from WheelsBridge AB was involved in the conduct of the study. The author JH is employed by the &#214;sterg&#246;tland County Council but has a royalty agreement with WheelsBridge AB. The senior author CDA has a full-time academic position but also limited involvement in WheelsBridge AB.

In order to get the best results with the system, variability caused by environmental factors must be controlled. All ambient light must be turned off. The camera must be positioned in vertical alignment with the measurement area. In order to ensure a constant measurement area, subjects should not move or talk during measurement. For the same reason, the camera is preferably mounted on a stand to avoid movement and to maintain a constant distance to the measurement area. Test subjects should avoid caffeine<sup class="xre...

Assessment and triage of the critically ill patient centers on the classical vital signs blood pressure (BP), heart rate (HR), respiratory rate (RR), oxygen saturation, and body temperature1. Changes in these parameters appear relatively late in the course of circulatory deterioration. For instance, in hemorrhage, a decrease in BP will not occur until blood loss becomes moderate to severe2, and HR increase can also be an insensitive and unspecific marker3.
The capillary refill test (CR test) may offer an earlier indication of incipient circulatory collapse, as the refill time is believed to change prior to the vital signs as well as clinical appearance of cold, clammy, and mottled skin1,4,5. The capillary refill test is typically performed by application and then release of a firm blanching pressure to the skin with timing (in seconds) of the return of blood to the blanched area. According to guidelines, refill should occur within 2 seconds after release of 5 seconds of firm pressure (e.g., by the physician&#39;s finger) in the normal healthy supine patient6. The rationale for the test is that a slower refill time would indicate poor skin perfusion, possible caused by one of a number of critical events such as sepsis, blood loss, acute heart failure, or hypothermia.
At present, there is no consensus on a state of the art method for performing the CR test6,7,8,9,10. Contentious issues include lack of standardization of the actual blanching maneuver and the dependence on subjective (i.e., naked eye) assessments of the refill endpoint7,9,11. Furthermore, there are indications that gender influences CR time12,13. The temperature, both ambient and skin, is known to affect the capillary refill time, but to what extent is not clear. Lastly, the use of different measurement sites, peripheral or central, is probably a further cause of variability in results with few studies in this area14,15.
In the present work, we used an optical bioengineering system to record the course of return of blood and the subsequent hyperemic response seen during the CR test. The system utilizes diffuse polarization spectroscopy to quantify and describe, in more detail than possible with the naked eye, the time and course of the capillary refill. The system comprises a standard digital camera, fitted with an external light ring with 92 white LEDs, and specially developed software. The lens and the two polarization filters, attached orthogonally in front of the LEDs, block light that has been directly reflected from the skin surface allowing only light that has become depolarized in the tissue to reach the camera. This generates a &#34;sub-epidermal&#34; image of the tissue to a depth of approximately 0.5 mm. The image is divided into its color planes and the red and green content for every pixel is calculated, generating a value which corresponds to the tissue concentration of red blood cells16. In video mode, the temporal resolution of the system is 0.02 s.

<table>
	<tbody>
		<tr>
			<td>TiVi701 Camera</td>
			<td>WheelsBridge AB</td>
			<td>TiVi701 Camera, version 1.5.1</td>
			<td>Software</td>
		</tr>
		<tr>
			<td>TiVi700</td>
			<td>WheelsBridge AB</td>
			<td>TiVi700 Analysis, version 1.2.9</td>
			<td>Software</td>
		</tr>
		<tr>
			<td>Canon EOS 700D</td>
			<td>Canon U.S.A., inc.</td>
			<td>Canon EOS 700D</td>
			<td>Digital SLR Camera</td>
		</tr>
		<tr>
			<td>Camera stand</td>
			<td>Manfrotto</td>
			<td>681B</td>
			<td>Modified camera stand to hold the digital camera in position</td>
		</tr>
		<tr>
			<td>Camera stand</td>
			<td>Disa Denmark</td>
			<td>9020B</td>
			<td>Modified camera stand to hold the digital camera in position</td>
		</tr>
	</tbody>
</table>

diffuse reflectance spectroscopy: getting the capillary refill test under one's thumb

The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill should occur within 2 s after releasing 5 s of firm pressure (e.g., by the physician&#39;s finger) in the normal healthy supine patient. A slower refill time indicates poor skin perfusion, which can be caused by conditions including sepsis, blood loss, hypoperfusion, and hypothermia. Since its introduction, the clinical usefulness of the test has been debated. Advocates point out its feasibility and simplicity and claim that it can indicate changes in vascular status earlier than changes in vital signs such as heart rate. Critics, on the other hand, stress that the lack of standardization in how the test is performed and the highly subjective nature of the naked eye assessment, as well as the test&#39;s susceptibility to ambient factors, markedly lowers the clinical value. The aim of the present work is to describe in detail the course of the refill event and to suggest potentially more objective and exact endpoint values for the capillary refill test using diffuse polarization spectroscopy.

Filming the course of the capillary refilling generates vast amounts of data not possible to obtain by naked eye assessment. We suggest here new endpoints to further improve the usability of the CR test as an early indicator of deterioration in circulatory status. We call these endpoints: &#34;Baseline,&#34;&#160;&#34;Blood Zero&#34; (or &#34;BZ&#34;), &#34;Time to Return to Baseline 1&#34; (or &#34;tRtB1&#34;), &#34;Time to Peak&#34; or &#34;Tpk.&#34;&#160;The &#34;Baseline&#34; value is...

Watch this Scientific Journal Video about Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb at JoVE.com

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb

This protocol describes how the use of diffuse polarization spectroscopy can improve the clinical usefulness of the capillary refill test. We suggest a more detailed analysis of the course of the capillary refill in healthy volunteers using diffuse reflectance spectroscopy videos and new informatic endpoints.

The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill ...

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9.0K visualizações.  Region Östergötland. Este protocolo descreve como o uso da espectroscopia de polarização difusa pode melhorar a utilidade clínica do teste capilar. Sugerimos uma análise mais detalhada do curso do reenchimento capilar em voluntários saudáveis, usando vídeos de espectroscopia de reflectância difusa e novos pontos de extremidade de informáticos.