442
`
`BRAVERMAN AND KEH-YEN
`
`Vol. 81, N0. 5
`
`8b
`
`
`
`
`
`FIG 8. Model of valve at junction of 3 veins. 0, View of free edges of valve cusps. b, Valve spread open to show cusps. c, Valve in situ at
`junction of 3 veins. Arrows indicate presumed direction of blood flow.
`
`REFERENCES
`
`1. Braverman IM, Keh-Yen A: Ultrastructure of the. human dermal
`microcirculation. III. The vessels in the mid- and lower dermis
`and subcutaneous fat. J Invest Dermatol 77:297—304, 1981
`2. Yen A, Braverman 1M: Ultrastructure of the human dermal micro-
`circulation: the horizontal plexus of the papillary dermis. J Invest
`Dermatol 65:131—142, 1976
`3. Braverman IM, Yen A: Microcirculation in psoriatic skin. J Invest
`Dermatol 62:493—502, 1974
`4. Landis EM: Micro-injection studies of capillary blood pressure in
`human skinJ—Ieart 152209—228, 1930
`5. Eichna LW, Bordley J III: Capillary blood pressure in man. Com-
`
`parison of direct and indirect methods of measurement. J Clin
`Invest 18:695—704, 1939
`6. Mahler F, Muheim MH, Intaglietta M, Bollinger A, Anliker M:
`Blood pressure fluctuations in human nailfold capillaries. Am J
`Physiol 2362H888—H893, 1979
`7. Bloom W, Fawcett DW: A Textbook of Histology, 10th ed. Phila—
`delphia, WB Saunders, 1975, pp 410—413
`8. Weiss L, Greep R0: Histology, 4th ed. New York, McGraw-Hill,
`1977, pp 415—420
`9. Braverman IM, Sibley J: Role of the microcirculation in the treat—
`ment and pathogenesis of psoriasis. J Invest Dermatol 78:12—17,
`1982
`
`
`
`0022-2()‘ZX/83/81()5-0442$02.00/0
`THE JOURNAL or INVESTIGATIVE DERMATOLOGY, 81:442—446, 1983
`Copyright ((3) 1983 by The Williams & Wilkins Co.
`
`Vol. 81, No. 5
`Printed in U.S.A.
`
`Basal Perfusion of the Cutaneous Microcirculation: Measurements as a
`Function of Anatomic Position
`
`ETHEL TUR, M.D.,* MOSHE TUR, PH.D.,'[‘ HOWARD I. MAIBACH, MD, AND RICHARD H. GUY, PH.D.
`
`Department of Dermatology, School 0/ Medicine (ET, HIM), and School 0/ Pharmacy (RHG), University of California Medical Center,
`San Francisco, California, USA.
`
`Noninvasive optical techniques of photopulse pleth-
`ysmography (PPG) and laser Doppler velocimetry
`(LDV) have been used to identify regional variations in
`the basal skin blood flow of humans. The procedures
`assess either the volume (PPG) or the volume-velocity
`product
`(LDV) of cutaneous blood vessel perfusion.
`Fifty-two anatomic positions have been studied in 10
`normal subjects resting horizontally. The mean perfu-
`sion levels were ranked to reveal the variations in cu-
`taneous blood flow as a function of body site. Groups of
`
`data were collected into cohorts and average perfusion
`values for the subjects within each cohort were com-
`pared by the Newman-Keuls multiple comparison test.
`Most transparently, the results reveal a collection of
`regions (fingers, palms, face, ears) for which cutaneous
`perfusion is much higher than all other positions. More
`subtle differences and some unexpected similarities,
`however, are also apparent and, in some cases, agree or,
`in others, conflict, with previously published informa-
`tion. With some exceptions, good general agreement
`between the two techniques was observed.
`
`Manuscript received April 19, 1983; accepted for publication June
`17, 1983.
`* Permanent address: Ichilov Medical Center, Dermatology Depart-
`ment, Tel Aviv, Israel.
`[Information Systems Laboratory, Stanford University, Stanford,
`California 94305.
`Reprint requests to: Richard H. Guy, Ph.D., School of Pharmacy (S—
`926), University of California, San Francisco, California 94143.
`Abbreviations:
`LDV: laser Doppler velocimetry
`PPG: photopulse plethysmography
`Page 1
`
`Regional variations in skin blood supply have been recog-
`nized for many years and numerous investigators have em-
`ployed a variety of techniques to estimate skin perfusion [1].
`This high level of study is understandable in terms of the
`physiologic importance of an efficient skin blood supply. For
`example, the cutaneous blood flow has a major thermoregula-
`tory function [2], it has an obvious nutritional role [3], it has
`been identified as crucial
`in the successful healing of skin
`wounds [4], and its dysfunction may be implicated in a number
`VALENCELL EXHIBIT72012, IPR2017-00321
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`

`Nov. 1983
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`BASAL CUTANEOUS BLOOD FLOW AS A FUNCTION OF ANATOMIC POSITION
`
`443
`
`Of clinically significant situations (e.g., Raynaud’s disease [5],
`chronic ulcers [6]). Apparent from the literature are clear
`differences in cutaneous blood supply to different anatomic
`regions and it is the further detailed probing of this dependence
`which this paper addresses.
`Hertzman and associates [5,7,8] provided the earliest esti-
`mates of regional differences in skin blood flow. They used a
`photoelectric plethysmograph and concluded that flow to the
`skin of the trunk, arms, and legs was essentially equal, and
`much less than that to the palmar and plantar surfaces, and
`that in the skin of the face and head. In addition to these
`qualitative observations, an attempt was made to quantify the
`various perfusion levels in terms of a volume per unit area per
`unit time. Such a quantification has been the goal of much
`work, which has been well summarized [1]. Many different
`procedures have been employed, including plethysmography,
`venous occlusion methodology, radioactive tracer clearance
`techniques, and local heat loss [1,3]. Absolute comparisons
`among anatomic sites are awkward, however, because of the
`variety of detection means and the inconsistencies in the sub-
`ject population and measurement conditions. Some studies,
`though, do allow certain relative regional skin blood flow as—
`sessments to be made. For example, Buchanan et a1 [9] used
`the clearance of 2“Na“ as an index of local circulatory efficiency
`and found (i) that skin blood flow was noticeably faster in the
`forehead than in the leg, and (ii) that symmetrical areas of
`pretibial skin in normal subjects at rest had equal blood flow.
`The latter conclusion has also been substantiated elsewhere
`[10]
`in a more complete study. Sejrsen [11] employed the
`washout of radioactive “”Xe (delivered both by intracutaneous
`injection and by nontraumatic epicutaneous application) to
`measure skin blood flow in humans. Perfusion was estimated
`to be about 6 ml/100 g/min in the leg, 5 nil/100 g/min in the
`arm, slightly less in the abdomen, and 2—3 times greater in the
`cheek. Lundberg and Smedegard [2] have determined regional
`differences in skin blood flow using radioactive microspheres
`in rat and monkey animal models and have found that skin
`blood flows were significantly higher in the thoracic region than
`in the lumbar and sacral regions.
`In this paper, relative assessments of basal regional skin
`blood flow in humans are presented. Data have been obtained
`at 52 different anatomic positions in 10 subjects using 2 tech-
`niques. The methods employed are photopulse plethysmogra—
`phy (PPG) [12,13] and laser Doppler velocimetry (LDV) [14—
`18]. Both these optical procedures are noninvasive and collect
`the perfusion information via small sensors positioned directly
`on the skin surface. The procedures do not quantitate skin
`blood perfusion (as a volume/weight of tissue/unit time) and it
`is questionable whether they can do so even with an indepen-
`dent “calibration.” They do, however, produce outputs known
`to be related to fundamental skin perfusion characteristics, i.e.,
`volume and flow rate (how much and how fast). They also
`generate this information in situ in humans with vanishingly
`small
`tissue perturbation. As such,
`it has been possible to
`perform some accurate, controlled comparisons of regional skin
`blood flow to a much larger number of sites on the human body
`than has been attempted before.
`
`MATERIALS AND METHODS
`
`Photopulsc Plcthysmography (PPG)
`Descriptions of this procedure have appeared previously [12,13]. An
`infrared light emitting diode directs radiation into the skin. The wave-
`length range of the source (800—940 nm) spans a region for which the
`tissue is relatively transparent; on the other hand, hemoglobin absorbs
`strongly in this part of the spectrum and hence the backseattered
`radiation, which is measured with a phototransistor, contains infor-
`mation about the volume of blood in the skin site under observation.
`As with LDV, PPG is believed to monitor the microcirculation to a
`depth of 1—2 mm [13,14]. Again, radiation is transmitted to the skin
`and received back via a small probe (housing the diode and phototran-
`sistor) held in position by double-sided adhesive tape. Processing of
`
`Page 2
`
`the blood volume fluctuations is performed by a photoplethysmograph
`(Medasonics, Mountain View, California). Increases in perfusion are
`registered by an enhancement Othe amplitude of the output pulsations
`[8,12,13}.
`
`Laser Doppler Velocimctry (LD V)
`A laser Doppler velocimeter [14»18] (LD5000, Medpacific Inc., Se-
`attle, Washington) was used. Light at (‘f 2.8 nm from a 5 mW He—Ne
`laser is transmitted to the skin through an optical fiber. Doppler»
`shifted backscattered light from mobile red blood cells is collected by a
`similar optical fiber which guides the radiation back to the instrument.
`The detected signal
`is processed to produce an output which is a
`complicated function of the blood velocity and the effective blood
`volume within the field of view of the 2 fibers. Cardiac pulsations
`appear in the recorded waveform, but it
`is the envelope of these
`pulsations that is the quantity of interest. Physical support to the fibers
`at the point where they interface with the skin is provided by a small
`cylindrical probe which is attached to the application site using a
`double—sided adhesive perforated disc.
`
`Experimental
`Ten subjects were studied. The volunteers were healthy, young (20—
`30 years) men. Measurements were made in a single, well-ventilated
`room under reasonably constant temperature and humidity conditions
`(T = 23 : 2°C, RH = 504096), to which the subjects were acclimatized
`for 15 min prior to the acquisition of PFC and LDV data. Measure-
`ments were taken from nude subjects in either a supine or prone
`position. Recordings from the 52 anatomic sites investigated (see Fig
`1) were obtained consecutively over a 3- to 4-h period. Readings at any
`particular site were averaged over about 3 min by analyzing the recorded
`output. At each position, PPG and LDV measurements were made
`within 10 min of one another. Recordings were taken specifically from
`positions to the left of or on the midline. In a limited number of
`examples studied, bilateral measurements were indistinguishable. Be—
`fore any perfusion readings were rnade by PPG, the plethysmograph
`was calibrated with an Oscillating reflection device which provides a
`constant signal for equalization of the PPG sensor's sensitivity. Prior
`to the measurement of blood flow by LDV, the capillary perfusion
`monitor was zeroed using its internal circuitry.
`
`7
`3
`
`11
`
`9
`
`32
`a
`21
`22
`2
`
`1
`2
`
`3
`h
`5
`in.
`,5
`,6
`17
`18(hee1)
`19
`20(toe)
`
`I"
`
`25
`26
`
`\
`27
`Za\ '
`\"
`29
`3‘
`no
`t,
`“2
`#3
`
`so
`31
`12
`is
`
`35
`as
`37
`as39
`
`NS
`
`“A
`146
`
`51(postaur1cular)
`
`/
`I/ 5°(back of car)
`‘
`w
`k9
`MB
`
`
`
`52
`
`FIG 1. Anatomic positions identified by site number, for which basal
`cutaneous perfusion measurements were performed by PPG and LDV.
`
`Page 2
`
`

`

`L10
`
`AVERAGE PPG -
`ASSESSED
`PERFUSlON (MM)
`
`Vol. 81, No. 5
`
`”9
`x
`
`48
`X
`
`L,
`)8
`
`”7
`X
`
`50
`X
`
`J)?
`
` 0
`
`35
`
`70
`
`AVERAGE LDV - ASSESSED PERFUSION (MM)
`
`FIG 4. Plot of mean PPG perfusion measurement (1 mm = 10 mV)
`vs the corresponding LDV mean (1 mm = 20 mV) for the 52 anatomic
`positions studied. The sites of high PPG and LDV assessed perfusion
`values are indicated by number on the graph.
`
`TABLE I. Multiple comparisons of cutaneous perfusion measurements“
`for the anatomic position groups designated cohort A: trunk, upper
`
`limb, lower limb, foot, hand,’1 and face
`Lower
`Upper
`
`limb
`limb
`Foot
`Hand
`Face
`N
`N
`N
`**
`**
`Trunk
`N
`N
`**
`**
`Upper limb
`N
`**
`**
`Lower limb
`**
`**
`Fout’
`
`Hand *, N
`" Where 2 entries appear in the Table, PPG assessment is given first,
`then LDV; otherwise, PPG and LDV agree.
`” Palmar surface only.
`The groups have been multiply compared using the Newman-Keuls
`statistical test [19] and differences have been assessed at the p = 0.05
`and p = 0.01 levels of significance. The entry N in the Table means
`that perfusion of the 2 groups compared is not significantly different.
`The entry of 1 (p = 0.05) or 2 (p = 0.01) asterisks means that the group
`in the left-hand column has significantly lower perfusion than the
`paired group in the top row of the Table.
`
`TABLE II. Multiple comparisons of cutaneous perfusion
`measurements" for cohort B: side of the trunk, lower leg, upper leg,
`arm, lower trunk, upper trunk
`W 1'
`er
`
`Ls,“
`A...
`”it?
`143...:
`133%].
`**
`**
`an
`an
`**
`Side
`N
`N
`N
`H, *
`Lower leg
`N
`N
`N, *
`Arm
`N
`N
`Upper leg
`
`Lower trunk N, *
`
`“ Where 2 entries appear in the Table, PPG assessment is given first,
`then LDV; otherwise, PPG and LDV agree.
`The methods of comparison and Table entries are as described for
`Table I.
`.
`
`TABLE III. Multiple comparisons of cutaneous perfusion
`measurements“ for cohort C: hand,” finger, postauricular region (PAR),
`
`back of ear, ear lobe, and face
`Back of
` PAR Finger Face ear Earlobe
`
`
`
`
`Hand
`N
`*, N
`N
`**, N
`**, N
`PAR
`N
`N
`H, N
`**, N
`Finger
`N
`N
`N
`Face
`N
`N
`
`Back of ear N
`
`" Where 2 entries appear in the Table, PPG assessment is given first,
`then LDV; otherwise, PPG and LDV agree.
`" Palmar surface only.
`The methods of comparison and Table entries are as described for
`Table I.
`
`444
`
`TUR ET AL
`
`RESULTS
`
`The experimental data, as measured by the PPG and LDV
`techniques respectively, are summarized in Figs 2 and 3. These
`graphs show the ranked means, together with their respective
`SD, for the 52 anatomic sites studied. In Fig 4, a scatter plot of
`mean PPG measurement vs mean LDV determination is pre-
`sented. The anatomic sites having high PPG and LDV assessed
`perfusion values are identified by number on the graph.
`To statistically address the perfusion measurements, a simple
`first step is to compare the ranked means in pairs by a repeated
`measures test
`[19]. This is a dubious procedure, however,
`because, although the results may be used to compare perfusion
`at any pair of sites with the prescribed level of significance,
`comparisons among several different pairs are less significant
`[20]. Therefore, we have divided the various sites into groups
`and ranked up to 6 group means using the Newman-Keuls
`multiple comparison test [19]. The statistical results for the 3
`groupings chosen are presented in Tables I—III. The point
`should be made that each set of comparisons (i.e., each individ-
`ual Table) must be interpreted individually and that conclu-
`sions drawn by comparing statistical differences in 2 different
`Tables are less significant.
`60
`
`RANKING
`(l=LOHEST,
`52=HlGHEST)
`
`30
`
`JD
`DATA
`BASAL CUTANEOUS PERFUSION (MM).
`ARE [MEAN + S.D. J ASSESSED BY 2%.
`FIG 2. Basal cutaneous perfusion measurements assessed by PPG.
`The sites are ranked according to the mean values obtained and are
`presented with their respective SD. PPG units are signal amplitude
`magnitude in mm (1 mm is equivalent to 10 mV).
`60
`
`an
`
`RANK l NG
`(1=LOHESI,
`52 =H l GHEST)
`
`JD
`
`DATA
`BASAL CUTANEOUSGEERFUSlON (MM).
`ARE [MEAN + 8.1]. ] ASSESSED BY L01.
`
`120
`
`FIG 3. Basal cutaneous perfusion measurements assessed by LDV.
`The sites are ranked according to the mean values obtained and are
`presented with their respective SD. LDV units are signal magnitude in
`mm (1 mm is equivalent to 20 mV).
`
`, Pages
`
`Page 3
`
`

`

`Nov. 1983
`
`BASAL CUTANEOUS BLOOD FLOW AS A FUNCTION OF ANATOMIC POSITION
`
`445
`
`DISCUSSION
`
`The extensive data gathered in this study can be used to
`compare the degree of perfusion at various anatomic sites over
`most surfaces of the body, as well as to investigate the corre-
`lation between the results of 2 measuring techniques, namely,
`PPG and LDV.
`The means and SD at the various sites as obtained by the 2
`methods appear in Figs 2 and 3, respectively. As a first approx-
`imation those figures identify 2 broad groups: (a) a large number
`of sites with “low" skin blood perfusion, and (b) a collection of
`positions with elevated microcirculation. We note that the
`variation in the latter (as measured by the SD) is much greater
`than the former.
`This broad division can be observed also in Fig 4, where the
`results of the PPG and LDV correlate fairly well only for those
`Sites with low readings. The body positions not associated with
`the low PPG—low LDV cluster are found on the head, face,
`ears, fingers, and palms. It is appropriate to note that these are
`the same anatomic positions associated with large and complex
`cutaneous arteriovenous shunts [21].
`To facilitate a statistically significant comparison of the large
`number of experimental results that has been obtained, it was
`decided to group together parts of the data and then compare
`the mean perfusion levels of the chosen groups. The selection
`of the various groups is, by necessity, somewhat arbitrary, and,
`in the examples presented, has been performed anatomically.
`Multiple comparisons among groups have been performed by
`the Newman-Keuls statistical test [19] and differences have
`been assessed at both the p = 0.05 and p = 0.01 levels of
`significance.
`The first set of groups (cohort A) considered was: trunk,
`upper limb,
`lower limb, feet, hands, and face. The multiple
`comparisons for the PPG results and LDV data are given in
`Table I. Cohort A contains regions of 2 distinct characteristics.
`The hands and the face represent anatomic regions of high
`cutaneous perfusion relative to all other sites on the body.
`Within this cohort, positions on the body excluding the hands
`and face are not distinguishable from one another. PPG and
`LDV are in complete agreement in comparing this cohort with
`the minor exception that PPG finds the face more highly
`perfused than the hands (at p = 0.05) whereas LDV suggests
`no difference.
`Results for cohort B (side of the trunk, lower legs, upper legs,
`arms, lower trunk, and upper trunk) are statistically ranked in
`Table I]. Once again, apart from a few discrepancies at the p =
`0.05 level of significance, PPG and LDV are in good agreement.
`Within these groups, it is observed that the sides of the body
`are relatively poorly perfused compared to all other regions.
`Interestingly, it is found that the blood supply to the lower leg
`is significantly less than that to the upper trunk, whereas
`perfusion to the upper leg is not statistically different than that
`to the upper trunk. It may be suggested, therefore, that there
`is some indication in these comparisons (despite the statistical
`equivalence between upper and lower legs) of a contributory
`factor as to why wounds on the lower leg heal more slowly than
`elsewhere [22].
`Cohort C (Table III) comprises 6 “high” blood flow groups:
`hand, finger, postauricular region, back of ear, ear lobe, and
`face. Multiple comparisons of the PPG information in this
`cohort are clearly different from those of the LDV data. LDV
`does not distinguish among any of the groups, and finds, at the
`levels of significance tested, that blood flow to all these regions
`is similar. It is possible that, because of the large SD associated
`with the LDV values for these sites, the subject group studied
`may not have been sufficiently large to allow any real differ-
`ences to be found. PPG, however, identifies the back of the ear
`and the ear lobe as much more highly perfused regions than
`either the palm or the postauricular region (p = 0.01). At a
`lower level of significance (p = 0.05), the palmar surface of the
`finger is identified as more highly perfused than the palm.
`
`Page 4
`
`These results are consistent with known characteristics of
`human facial flushing [23].
`When the results of this study are compared with those in
`the literature, there are areas of agreement and discrepancy. In
`the former case,
`the early, careful work of Hertzman and
`colleagues [5,7,8] is confirmed qualitatively and is statistically
`proved for a larger subject population. The identification of the
`facial region as a skin area much better perfused than the
`majority of the rest of the body is consistent with the half-lives
`for 2“Na* clearance, forehead skin vs tibial skin, observed by
`Buchanan et a] [9]. Fig 4, furthermore, provides more justifi—
`cation for this conclusion. The existence of a group of regions
`(face, ears, fingers, palms) with high LDV and PPG readings
`suggests that the residence time of a unit volume of cutaneous
`blood at these sites is short relative to the other anatomic
`positions. Consequently, the clearance of injected radiolabel
`into these highly perfused areas is expected (and is found) to
`be relatively rapid. [Of course, one may envisage clinical situ-
`ations (e.g., full or partial venous occlusion) for which total
`volume can be increased and flow decreased thereby yielding
`discrepancy between PPG and LDV assessed perfusion]
`Disagreement between the investigation reported here and
`that performed by Lundberg and Smedegard [2] is apparent.
`Whereas these authors found that thoracic skin blood flow
`exceeded lumbar and sacral perfusion, no such differentiation
`was detected by LDV and PPG. However, this recent work was
`carried out in rats and monkeys, for which comparable nonin-
`vasive blood flow assessments are not currently available, and
`thus direct comparisons are somewhat tenuous.
`In conclusion, the basal perfusion of the cutaneous microcir-
`culation has been measured comprehensively as a function of
`anatomic position by 2 noninvasive optical techniques. Statis—
`tical assessment of the results has revealed important similar-
`ities and differences in resting skin blood flow. Because the
`detecting methodologies operate on different principles, there
`is potential in further experimentation to probe more closely
`the characteristics and origins of variable levels of regional
`cutaneous perfusion.
`
`The authors. thank Mrs Johanna Hunt and Dr. Moshe Polak for
`helpful discussions. We are also indebted to Dr. Herschel Zackheim
`whose interest in skin blood flow catalyzed the performance of this
`study.
`
`REFERENCES
`
`10
`
`1. Altman PL, Dittmer DS: Respiration and Circulation. Bethesda,
`Md, Federation of American Society for Experimental Biology,
`1971, pp 431—434
`. Lundberg C, Smedegard G: Regional differences in skin blood flow
`as measured by radioactive micrOSpheres. Acta Physiol Scand
`111:491—496, 1981
`3. Greenfield ADM, Whitney RJ, Mowbray JF: Methods for the
`iliééegstigation of peripheral blood flow. Br Med Bull 19:101—109,
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`5. Hertzman AB: The blood supply of various skin areas as estimated
`1:3;th photoelectric plethysmograph. Am J Physiol 124:323—340,
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`8. Hertzman AB, Randall WC: Regional differences in the basal and
`maximal rates of blood flow in the skin. J Appl Physiol 1:234~
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`9. Buchanan TJ, Walls EW, Williams ES: Studies in radiosodium
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`Page 4
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`

`

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`TUR ET AL
`
`Vol. 81, No. 5
`
`vol 1. Edited by P Rolfe. London, Academic Press, 1979, pp 125—
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`13. Tur E, Guy RH, Tur M, Maibach HI: Noninvasive assessment of
`local nicotinate pharmacodynamics by photoplethysmography. J
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`14. Guy RH, Wester RC, Tur E, Maibach HI: Non-invasive assess—
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`15. Holloway GA, Watkins DW: Laser Doppler measurement of cuta-
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`18. Bonner RF, Chen TR, Bowen PD, Bowman RL: Laser—Doppler
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`19. Winer BJ: StatisticalvPrinciples in Experimental Design, 2nd Ed.
`New York, McGraw-Hill, 1971, chap 3
`20. Klugh HE: Statistics: The Essentials for Research, 2nd Ed. New
`York, John Wiley & Sons, 1974, chap 11
`21. Hamilton WF, Dow P: Handbook of Physiology, sec. 2: Circulation.
`vol II. Washington DC, American Physiological Society, 1963,
`p 1252—1253
`22. Samitz MH: Cutaneous Disorders of the Lower Extremities, 2nd
`Ed. Philadelphia, JB Lippincott, 1981, pp 1—3
`23. Wilkin JK: Flushing reactions, Recent Advances in Dermatology,
`vol VI. Edited by A Rook, HI Maibach. London, Churchill
`Livingstone, 1983, in press
`
`
`
`0022-202X/8:1/s105-1)446$02.(>0/0
`’I‘nr. JOURNAL or INVESTIGATIVE DERMATOLOGY, 81:446—448. 1983
`Copyrightlilr 1983 by The Williams & Wilkins Co.
`
`Vol. 81, No. 5
`Printed in (1.8.14.
`
`Effect of a Skin Moisturizer on the Water Distribution in Human
`
`Stratum Corneum
`
`MAW—SHENG Wu, PH.D., DIANA J. YEE, B.S., AND MAUREEN E. SULLIVAN, B.S.
`Personal Care Division, The Gillette Company, Boston, Massachusetts, USA.
`
`The effect of a skin moisturizer on the water content
`distribution in human stratum corneum was examined
`from the rate of water loss from the skin surface. An
`increase of 9% in the water content was calculated from
`the water loss data. This increase was not evenly dis-
`tributed across the tissue. Most of the increase occurred
`near the skin surface. In the first one-tenth of the stra-
`tum corneum the increase was estimated to be about
`100%.
`
`Water is known to be a good plasticizer for stratum corneum
`[1]. The occlusive effect of a skin moisturizer on the water
`content in stratum corneum may be evaluated from the changes
`in the rate of transepidermal water loss (TEWL).
`In this paper, we report the quantitative Changes in the water
`concentration profile across the thickness of the stratum cor—
`neum calculated from the changes in the TEWL rates before
`and after the application of a skin moisturizer.
`
`METHODS
`
`Female subjects were recruited for the study. Prior to testing, the
`panelists washed their forearms with a mild detergent, rinsed with
`warm water, and patted dry. The washing procedure was followed by a
`'30 min equilibration period in a room that was maintained at a constant
`humidity (3%1 RH) and temperature (22" C). This period allowed the
`panelists to adjust to the conditions of the testing environment. One
`site was delineated on each forearm, and the rate of water loss was
`determined at each site After the measurements were taken, one of
`the sites (randomly selected) was treated with 0.03 ml of a moisturizer
`
`Manuscript received March 9,1983; accepted for publication May
`25, 1983.
`Reprint requests to: Maw~Sheng Wu, Ph.D., Personal Care Division,
`The Gillette Company, Gillette Park, Boston, Massachusetts 02106
`Abbreviations:
`RH: relative humidity
`TEWL: transepidermal water loss
`
`on a 16 cm2 area. The water loss measurements were repeated on both
`sites at (1'0, 90, and 120 min posttreatment.
`The Evaporimeter EP 1 (Servomed, Sweden) was used to obtain the
`rate of water loss [2]. The output from the instrument was interfaced
`with an Apple II computer. The computer was programmed to acquire
`1 data point per 4 s for 4 min and to perform a statistical analysis at
`the end of the measurement.
`
`RESULTS AND DISCUSSION
`
`It is known that the rate of water loss is affected by environ-
`mental factors. Therefore, the measurements were made in a
`room that was maintained at a constant humidity and temper-
`ature. The air current in the room was also minimized during
`the measurement. Another major factor influencing the rate of
`water loss15 the physiologic state of the panelist. To alleviate
`the possibility of this interference, each panelist was asked to
`rest in the testing room for 30 min before actual testing began.
`The possible site-to—site variation was eliminated by the ran—
`dom selection of the treated sites.
`The instrument used to obtain the TEWL rates measures
`the water vapor gradient on the skin surface. Therefore, theo-
`retically, the measurements are instantaneous. However, the
`readings on the instrument can fluctuate very fast, making
`accurate readings difficult. By carefully controlling the envi-
`ronment during the measurements and by using a microcom-
`puter to acquire the data, this difficulty may be eliminated.
`With each measurement, 2400 data points were collected from
`the Evaporimeter and analyzed statistically by the computer.
`It was found that the standard deviation in each measurement
`was about 15%.
`The pretreatment value obtained here (7.95 i 3.63 g/m2 h)
`was in the same range as those reported by other investigators
`using different techniques [3,4]. Table I shows the effect of a
`moisturizer on the rate of water loss. It can be seen that the
`rate was reduced after the application of the moisturizer. To
`avoid possible effects caused by the time differences in the
`measurements, the results were obtained using the ratios of the
`
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