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EPUAP Guest Session: Support Surfaces, Microclimate and Skin Conditions
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Free Paper Session: Infection
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BIOMECHANICAL MODELING OF MICROCLIMATE FACTORS AND
THEIR EFFECT ON SKIN INTEGRITY
Amit Gefen 1
THE ROLE OF TOPICAL NEGATIVE PRESSURE FOR THE TREATMENT OF DEEP
STERNAL WOUND INFECTION: SINGLE CENTER EXPERIENCE FROM THE
NEONATAL AGE TO THE OCTOGENARIAN
1 Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University
(Tel Aviv, Israel).
Marisa De Feo 1 , Veronica D’oria 1 , Ester Della Ratta 1 , Giuseppe Petrone 1 ,
Andrea Petraio 2 , Fabio Ursomando 2 , Giuseppe Caianiello 2 , Alessandro Della Corte 1 ,
Pasquale Santè 1 , Gianantonio Nappi 1
Aim: Biomechanical models of skin in interaction with support surfaces were developed
to determine effects of wetness, ambient temperature and humidity, age, and wrinkles
on mechanical loads in skin in order to understand the effects of microclimate factors on
skin tolerance to superficial pressure ulcers (SPUs)
1 Dpt Cardiothoracic Science Second University of Naples (Naples, Italy);
2 Dpt Cardiovascular Surgery and Transplant, Monaldi Hospital Naples, Italy.
Aim: To review our experience in the treatment of deep sternal wound infections (DSWI)
with topical negative pressure.
Methods: We used mathematical and computational (finite element, FE) modeling. The
mathematical modeling included effects of wetness-related friction on skin shear
stresses and shear strength. Using FE, we further modeled young versus aged skin,
which differ in mechanical properties as well as in depth of wrinkles.
Results: The modeling identified the following factors as such that decrease the
tolerance of skin to SPUs: (i) increase in skin temperature, (ii) increase in ambient
temperature, (iii) increase in relative humidity, (iv) increase in skin/support contact
pressures, and (v) decrease in permeabilities of the materials contacting the skin or
being close to it, e.g. covering sheets of the support and clothing. Compression and
shear with wetness produced the highest skin surface loads. Volumetric exposure of
aged skin to potentially injurious shear stresses was 6-times greater than in the young
skin. Deeper wrinkles caused elevated loads in the stratum corneum (SC).
Methods: Between October 2004 and December 2012, 9903 patients underwent cardiac
surgery at our institution (7488 cases in the adults, 2415 cases in pediatric or neonatal
age). DSWI occurred in 84 patients (0.84%; 58 adults, 52 male, 32 female). Mean age
was 63±25 years (range 6 days-79 years). In adults, cardiac diseases leading to
operation included: 38 coronary artery disease, 9 aortic valve disease, 5 mitral valve
disease, 6 cardiomyopathies; in newborn/children: 8 transposition of the great arteries, 1
hypoplastic/single ventricle, 4 tetralogy of Fallot, 5 interventricular septum defect, 2 aortic
coartation. Diabetes and obesity coexisted in 34 adults. The mean interval between
operation and infection was 27±14 days. Most frequent pathogens were: Staphylococci
Aurei in 33%, Epidermidis 26%.
Conclusions: The modeling is consistent with relevant empirical findings and clinical
observations in the literature, explains them from a basic science aspect, and can be
further developed for designing interventions, safer patient clothing and supports that
consider optimization of microclimate factors. Our findings indicate that wetness, skin
aging, and/or skin wrinkling are all risk factors for SPUs.
Results: One adult and one pediatric patients died during DSWI treatment (2.4%
mortality). Causes of death were multi-organ failure and low output syndrome
respectively. The median healing time was 14±5.5 days in adults (range 7-30 days), 14±
2.3 in pediatric patients (range 11-18 days). DSWI did not recur following topical
negative pressure* treatment in any case. Mean hospital-stay was 29±12 days in the
adult, 29±11 in the pediatric age.
Conclusions: Negative-pressure wound therapy improves the prognosis of poststernotomy
DSWI, reduces the risk of reinfection and the time needed for wound healing.
It can be considered the first choise approach for poststernotomy DSWI.
* VAC
EPUAP GUEST SESSION: SUPPORT SURFACES, MICROCLIMATE AND SKIN CONDITIONS
EWMA 2013
COPENHAGEN
15-17 May · 2013
Danish Wound
Healing Society
31