Indian Journal of Paediatric Dermatology

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 22  |  Issue : 4  |  Page : 326--332

Measurement of epidermal hydration and skin ph in infants with atopic dermatitis before and after a bath


Pirabakaran Sivanesan1, Thulasi Weerasinghe1, Kavindra Nanayakkara1, Praneeth Ratnayake2, Sriyani Samaraweera1, Jayamini Seneviratne1,  
1 Department of Dermatology, Lady Ridgeway Hospital for Children, University of Colombo, Colombo, Sri Lanka
2 Department of Zoology and Environment Sciences, University of Colombo, Colombo, Sri Lanka

Correspondence Address:
Pirabakaran Sivanesan
Department of Dermatology, Lady Ridgeway Hospital for Children, Colombo
Sri Lanka

Abstract

Introduction: The skin barrier function resides primarily in the stratum corneum (SC). Defect in SC hydration and skin surface pH leads to barrier impairment causing atopic dermatitis (AD). We have noticed a clinical improvement in infants with AD after a bath. We aimed to assess barrier functions in infants with AD before and after a single bath. There are no large controlled studies that clarify the optimal parameters of bathing. However, there are few studies recommending bath in AD. We proposed a “twenty minutes immersion bath.” Materials and Methods: We conducted an interventional analytic study without comparison group. The main instruments used were the corneometer and skin pH meter. Results: The measured values of SC hydration were significantly higher on the lesional skin immediately after a bath (P < 0.001). The mean SC hydration dropped dramatically within one hour and gradually reduced further over the next three hours. However, healthy looking skin had short climb and slow drop of SC hydration. The measured values of skin pH were lower on the lesional skin after bathing (P = 0.026). Discussion: An immersion bath improves SC hydration and helps to maintain skin pH and warrants further evaluation in the context of atopic dermatitis.



How to cite this article:
Sivanesan P, Weerasinghe T, Nanayakkara K, Ratnayake P, Samaraweera S, Seneviratne J. Measurement of epidermal hydration and skin ph in infants with atopic dermatitis before and after a bath.Indian J Paediatr Dermatol 2021;22:326-332


How to cite this URL:
Sivanesan P, Weerasinghe T, Nanayakkara K, Ratnayake P, Samaraweera S, Seneviratne J. Measurement of epidermal hydration and skin ph in infants with atopic dermatitis before and after a bath. Indian J Paediatr Dermatol [serial online] 2021 [cited 2021 Dec 5 ];22:326-332
Available from: https://www.ijpd.in/text.asp?2021/22/4/326/327455


Full Text



 Introduction



Skin is primarily an organ of protection. It protects the interior milieu from a wide variety of external factors. Among these are microbes, allergens, chemicals, and ultraviolet radiation. Further it conserves water by preventing transepidermal evaporation. To achieve these functions, well-organized physical, biological, chemical, immunological, and structural adaptations are seen in the stratum corneum (SC). SC barrier function depends on several factors: SC hydration, acid mantle, cationic antimicrobial peptides (CAMPs), arrangement of corneocytes, amount, and composition of extracellular lipids. SC hydration and acid mantle are the essential components of the skin permeability barrier and to a lesser extent that of antimicrobial barrier.[1],[2] SC hydration occurs both exogenously and endogenously. The former mainly is by bathing and by the application of moisturisers. The later prevents water evaporation from the SC. Water imbibing capacity of SC mainly depends on the level of natural moisturizing factor (NMF). In addition, retention of water in SC depends on several other structural adaptations. An acid mantle covers the skin surface with a pH of 4.5–5.5. This is made up of sebum, products of sweat and products of corneocytes including NMF and free fatty acids. Defect in NMF causes dry skin and high skin pH as seen in ichthyosis vulgaris. An alkaline pH leads to alteration of skin microbiome and increased activity of serine proteases which leads to subsequent corneodesmolysis and excessive desquamation. An impaired epidermal barrier clinically presents with inflammation, dry skin, and scaling which are the hallmark features of atopic dermatitis (AD).

The human fetus develops within an aqueous environment in utero. Neonates are born with a developing epidermal barrier that is more permeable and more reactive to the environment. The barrier development continues during the first year of life.[3] AD begins around the third month of life. It can be reasonable to argue that barrier functions deteriorate gradually in a xeric environment. Infant skin has immature sebaceous glands and skin microbiome. These contribute to staphylococcal colonization with toxin production adding to dermal inflammation. Water is the most natural and biocompatible product for living tissues. It plays a vital role in the functions of all organs including the skin. Bathing a child with AD has many advantages. It not only improves epidermal hydration but also has a cleansing effect by reducing the number of pathogenic microbes and removing allergens, irritants, crust, and scale.

The inflammation of AD results from both inherited and acquired defects of the skin permeability and antimicrobial barrier. We have noticed a dramatic clinical improvement in infants with AD after a bath. It can be argued that bath is a simple, safe, and natural measure of barrier protection in AD. It also controls and prevents establishment of inflammation. Bathing improves healing process by barrier recovery in AD. AD individuals are more prone to get infection due to various mechanisms including reduced production of CAMPs. There are no large controlled studies that clarify the optimal duration and frequency of a bath, temperature of water, use of bath additives and soap substitute for infants with AD. However, there are few studies recommending daily bath. We propose a “twenty minutes immersion bath” for AD. It means immerse the child up to neck level, in mixture of lukewarm water and bath emollient, at least once a day with aqueous cream as a soap substitute and a mild antiseptic shampoo (1% cetrimide lotion).

We have noticed a dramatic clinical improvement in infants with AD after a immersion bath. We intend to test this observation scientifically that skin permeability barrier functions by measuring SC hydration (by corneometer) and skin surface PH (by skin-PH-meter) of lesional and nonlesional skin in infants with AD before and after the twenty minute immersion bath.

 Materials and Methods



This study was conducted to assess permeability barrier functions by measuring SC hydration and skin surface pH in infants with AD before and after the twenty minute immersion bath.

This study was designed as interventional analytic study. There was no comparison group.

Twenty minutes immersion bath was the main intervention of the study. The infants were immersed up to neck level, in a mixture of lukewarm water mixed with a bath emollient for a twenty minute duration. Aqueous cream was used as a soap substitute and mild antiseptic shampoo (1% cetrimide shampoo) was used in all infants. It was carried by parents or guardian. SC hydration and skin surface pH were measured on the lesional skin and healthy looking skin. The serial measurements were performed before a bath as well as immediately, one hour and four hours after an immersion bath. All measurements were taken from the same areas of the individual. All the measurements were taken in triplicate to minimize error. The measurements were performed by noninvasive bioengineering method. All measurements were performed under constant ambient conditions. The room conditions were a temperature of 20 degrees C and 40%–60% relative humidity. It was achieved by using air condition room with an ambient conditioned sensor RTH 100. Our infants were allowed to rest for ten minutes in that room, prior to the bath.

The main instruments used were the corneometer for SC hydration and skin pH meter. Corneometer (CM 825): The multi display device MDD 4 (Courage and Khazaka electronic GmbH, Germany) corneometer (CM 825) that measures electrical capacitance of the skin surface which is expressed as arbitrary units (AU). This is an indirect measurement of SC hydration. This measurement is not influenced by substances in the skin (for example, salts or residues of topical applications). It allows very quick measurement (1 second). It is important to avoid occlusion. The measurement depth is very small (10–20 μm) to avoid the influence of deeper skin layers and blood vessels. Spring in the probe head ensures contact pressure on the skin enabling exact, reproducible measurements. It accuracy has been evaluated in a broad multicentric study.[5]

Skin pH meter (pH 905): Skin surface pH was measured with a pH 905 (Courage and Khazaka electronic GmbH, Germany) skin pH meter with a flat glass electrode. Before starting the measurement, the probe was washed in distilled water. Excessive water was wiped off the probe and care was taken to prevent excessive dryness. The probe-head was applied closely on the skin surface. Measurements were taken by using the button at the side of the probe.

Ethical review committee, Lady Ridgeway hospital [LRH/DA/05/2017] has granted ethical clearance on 26.10.2017.

Inclusion criteria

Infants with newly diagnosed ADAge range in between one month and one year

Exclusion criteria

Infants with erythroderma. (>90% body surface area involvement)Infants with severe skin sepsisInfants with high fever.

Data were analyzed using SPSS (v.20) (International Business Machines Corporation [IBM] Armonk, New York, United states). Means, standard errors, and standard deviations were calculated. One-way analysis of variance test was used to assess the differences between the results of measurements on the lesional and nonlesional skin of AD infants, before and after the twenty minute immersion bath. A level of P < 0.05 was considered statistically significant.

 Results



A total of 30 infants with AD were included in this study. The mean age of the cases was 4.33 months, and male-to-female ratio was 2:3. The mean measured SC hydration in infants with AD was 54.332 AU on lesional skin, before a bath. The measured values of SC hydration were significantly higher on the lesional skin when compared with the levels immediately after a bath and before bathing (P < 0.001). In addition, mean SC hydration dropped dramatically within one hour and gradually dropped in next three hours. However, the drop did not dip below the prebath level at four hours [Figure 1]. In infants with AD, the mean value of measured SC hydration was 75.147 AU on healthy looking skin before a bath. The measured values of SC hydration were significantly higher on the healthy looking skin when compared with immediately after a bath versus before bath (P < 0.001). In addition, mean SC hydration dropped dramatically within one hour and gradually dropped in next three hours. There were no significant differences among three values of before, one hour and four hours after bathing [Figure 2].{Figure 1}{Figure 2}

The mean skin surface pH value measured in infants with AD was 5.89 on lesional skin when measured before bath. The measured values of skin surface pH were significantly lower on the lesional skin immediately, one hour and four hours after bathing (P = 0.026). There was no significant difference among three values of immediate, one hour and four hours after bath. It is important to note that the skin surface pH drop persisted after bath over 4 h [Figure 3]. The mean skin surface pH value measured in infants with AD was 5.52 on healthy looking skin when before bath. There is a significant difference of skin pH values (P < 0.1: Confidence interval [CI] 90%) before bath and the value after four hours of bathing. Therefore, there is a significant reduction of skin pH before and after bath in healthy looking skin. In contrast, there is a significant (P < 0.05: CI 95%) reduction of skin pH immediately after bath in lesional skin [Figure 4]. The estimated marginal mean of SC hydration in lesional skin is significantly reduced in comparison with SC hydration in healthy looking skin before a bath. This pattern is maintained after a bath. However, lesional skin is more dynamic than healthy looking skin [Figure 5]. The estimated marginal mean of skin surface pH in lesional skin is significantly higher in comparison with skin surface pH in healthy looking skin. This pattern is maintained in after bath [Figure 6].{Figure 3}{Figure 4}{Figure 5}{Figure 6}

 Discussion



Skin is the crucial protective barrier between milieu interior and milieu exterior. This function resides primarily with the SC. The permeability barrier prevents ingress of allergens and antigens, while antimicrobial barrier protects from a plethora of microbes. For optimal protective functions, many structural adaptations have occurred in the SC. For example, protein-rich corneocytes are embedded in lipid-rich lamellar bilayers. This makes it an impenetrable layer for organisms and allergens. Apart from many similar structural adaptations, adequate hydration of SC and acid mantle is essential for its functional integrity. Defect in the above two leads to barrier impairment leading to inflammation, leading to AD. A Hydration of SC is the main aim in barrier-related management in AD. The prevalence of AD is as high as 15%–20% in children globally and continues to rise.[6] There are various studies providing correlation between the reduced level of SC hydration associated with increased transepidermal water loss (TEWL) and skin surface pH in AD.[7],[8],[9],[10],[11] However, few studies have a contradicted end results about TEWL and SC hydration.[12] Therefore, this study was done to assess skin barrier function by measuring SC hydration and skin surface pH. For example, a study of 21 AD patients and 21 healthy controls that measured SC hydration and skin surface pH, found skin barrier functions impairment in AD patients which is significantly expressed in lesional skin versus healthy looking skin.[7] Bathing was first proposed as a treatment for itchy and scaly skin conditions by Hippocrates 2500 year ago.[13] But later, clinicians questioned its efficacy.[13] The bathing practices in AD of children have been recommended in various accepted management guidelines. However, strength of recommendation and level of evidence varies among these guidelines. For example, bathing is suggested as the part of treatment and maintenance of AD in the American Academy of Dermatology 2014 guidelines, (level of evidence III and strength of recommendation C).[14] The European guideline for the treatment of AD in adult and children-2018 indicates the use of bath emollient and soap substitutes at the level of recommendations 3b/C.[15] However, duration and frequency of bathing are not clearly defined or vary in many guidelines.

There are few studies which determined best bathing practices in AD, with contradictory results. They provided evidence for the benefits, risks, or no effect of bathing in the treatment of AD. Most of these studies were assessed clinically. Few studies have objectively assessed skin barrier function by measuring SC hydration, TEWL and skin surface pH. However, all these studies had been done in adults, neonates, and children,[16],[17] None of the studies were done in infants, the group most commonly affected. Benefits were reported only in dead sea salt solution and acidic water bathing.[16],[18] Adverse outcome to bathing in AD was reported in one randomized controlled trial (RCT) but had a small sample size (5 AD individuals and 5 healthy controls) and bathing was without an emollient.[19] No effect of bathing in AD was reported in a few RCTs. One RCT had objective measurement of skin barrier function and they assessed between neonates with and without a family history of eczema. Here all, neonates were full-term healthy and had normal skin.[17] There were no controlled studies to suggest best bathing practice.[20],[21],[22] Bath additives such as rice starch and oatmeal or bleach baths may provide symptom relief in AD, but there appears to be no proven benefit in the treatment of AD. In addition, there is a lack of data about bathing and AD in pigmented skin. Some clinicians are reluctant to use bathing as an initial barrier-related treatment method in AD.[23]

Various methods are used for the measurement of epidermal barrier function. The most popular noninvasive methods are the measurement of SC hydration (by corneometer), skin surface PH (by skin-PH-meter), and transepidermal water loss (TEWL by Tewameter). Results of our study show the mean measured SC hydration value in infants with AD was 54.332 AU on lesional skin and 75.147 AU on healthy looking skin before a bath. SC hydration of the lesional skin was significantly reduced in comparison with healthy looking skin in infants with AD. This result is compatible with previous studies in AD.[7] The measured values of SC hydration were significantly higher on the lesional skin when compared immediately after a bath versus before a bath (P < 0.001). similar result was seen in healthy looking skin as well [Figure 1] and [Figure 2]. This indicates that a twenty minute immersion bath significantly hydrates the SC. In addition, mean SC hydration was noted to decline gradually in the next four hours. However, this did not reach the basal level. There were no significant differences between the values before and four hours after a bath. Similar pattern is shown in healthy looking skin as well [Figure 1] and [Figure 2]. Therefore, to maintain the hydration of SC for a long period, additional measures are needed. For example, this can be achieved by immediate application of emollients.

The mean skin surface pH value measured in infants with AD was 5.89 on lesional skin and 5.52 on healthy looking skin before a bath. This shows that pH of lesional skin was significantly increased in comparison with healthy looking skin in infants with AD. This result is compatible with previous studies in AD.[7] There was a significant (P < 0.05: CI 95%) reduction of skin pH immediate after a bath in lesional skin. There was no significant difference among three values of immediately, one hour and four hours after a bath. It is important to note that in lesional skin the skin surface pH reduction persisted after a bath up to four hours [Figure 3]. There was a significant difference of skin pH values (P < 0.1: CI 90%) before bathing and the four hours after a bath in healthy looking skin. It is important to note that the skin surface pH decline continued up to four hours after bath in healthy looking skin [Figure 4].

Before a bath, SC hydration in lesional skin as well as healthy looking skin was significantly reduced in infants with AD. This pattern was maintained in all three measurements following a bath. However, lesional skin was more dynamic than healthy looking skin with regard to SC hydration [Figure 5]. Skin surface pH in lesional skin was significantly higher in comparison with skin surface pH in healthy looking skin. This pattern was maintained in all three measurements following a bath [Figure 6]. Before and immediately after a bath, both SC hydration and skin surface pH show similar patterns in both lesional and healthy skin.

Conclusion

In conclusion, it can be said that an immersion bath improves SC hydration and helps to maintain skin pH. This at least partly proves our observation that infants with AD show some improvement in their clinical condition after a bath [Figure 7]. However, as mentioned above, there are some limitations. A better outcome could be obtained with continuous measurements following subsequent baths which will reflect the summation effect. Larger scale randomized controlled trials may be helpful to address these limitations.{Figure 7}

Limitations

Measurements were taken only up to four hoursNo control group includedMeasurements were taken only after a single bath.

Acknowledgments

The authors would like to thank Dr. Saman Gunasekara, (Former President, Sri Lanka College of Dermatologists) for providing a corneometer and skin pH meter and medical officers and nursing staff of Dermatology unit, Lady Ridgeway Hospital for technical help.

Declaration of consent

The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s) of the patient. In the form the parent(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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