Objetivos de la etapa

The research and theoretical articles comprising the sample reflect a wide spectrum of terms, themes and/or concepts related to burn wound assessment (Refer to Appendix R). It is vital that burn wounds are assessed accurately as it is an important determinant of the management and healing potential of the wound (Butcher & Swales, 2012: 50). The literature suggests that burn wound assessment should cover the size of the burn and the depth of the burn (Butcher & Swales, 2012: 50; Monstrey, Hoeksema, Verbelen, et al., 2008: 762; Miminas, 2007: 58), in other words burns must be classified.

142 A great deal of literature has been written on how burns should be classified. According to Mcquillan, et al., (2009: 866), burns are classified according to their depth and size. Likewise Roberts & Hedges (2010: 692), stated that burns are classified based on depth and size in addition to the source of the burn. Sheridan (2012: 33), included circumferential components along with size and depth. On the whole it can be concluded that the main criteria for classification of burn wounds are the depth of the burn and the size of the burn. The circumference will be included when the size of the burn is considered and will not be addressed as a separate topic in this thesis.

With respect to the classification of burns the depth of the burn and the size of the burn will be discussed separately.

Depth of the burn

The depth of the burn describes the tissue damage according to the anatomic thickness of the skin (Makik & Mann in Mcquillan, et al., 2009: 868). Burn depth assessment is not an exact science and is very subjective and is reliant on clinical assessment. On the other hand biopsy and histology are generally considered to be the gold standards for assessment of burn depth (Riordan, McDonough, Davidson, et al., 2003: 177–186). Although this may be true, biopsy and histology is invasive, painful, produces scars, is expensive, and requires an experienced pathologist and has therefore remained a research tool (Chatterjee, 2006: 123), and is therefore impractical for routine clinical use. According to Hettiaratchy & Papini (2004: 103), the extent and speed of capillary refill is considered the most useful clinical method to assess burn depth. However, testing for burn depth by using pinprick sensation might not be appropriate for all patients such as young children. Moreover, the accuracy of the test is limited (Bennett & Dingman, 1975: 261-272). It has been found that considerable variation between burn depth assessments performed by different clinicians occurred (Milseki, Atiles, Purdue, et al., 2003: 190), with clinical assessments found to only have accuracy rates of 60% to 70% (Monstrey, Hoeksema, Verbelen, et al., 2008: 761; Heimbach, Engrav, Grube, et al., 1983: 65–68; Engrav, Heimbach, Reus, et al., 1983: 1001–1004). This then is translated into up to 40% inaccuracy. In a patient with burns, size estimation informs management of the burn and it predicts outcomes (morbidity and mortality).

Newer technology such as Laser Doppler Imaging (LDI), transcutaneous microscopy, reflectance fluoroscopy, radioisotope studies, ultrasound and thermography promise more accuracy (Jaskille, Ramella-Roman, Shupet, et al., 2010). LDI provides an estimate of perfusion through the burn wound, the assumption being that a lower perfusion correlates with a deeper wound and, therefore, a longer time to heal according to Jaskille, et al., (2010: 152).

In a review done by Jaskille, et al., (2010: 151), it was argued that LDI is one of the most recent and most tested adjuvants to determine burn depth. Its quoted accuracy in predicting which wounds are

143 not expected to heal within three weeks is between 96% and 100%, and this is predicted in advance of clinical judgment by a median of two days. It is non-invasive, relatively fast, and seemingly simple to use according to Jaskille, et al., (2010: 151), and Monstrey, et al., (2008:7640). Devgan, Bhat, Aylward, et al., (2006: 10-11), were in agreement stating that the accuracy of Laser Doppler Flowmetry (LDF) and LDI ranges from 90% to 97% as compared to only 66% in a clinical evaluation. In a review by Jaskille, Shupp, Jordan, et al., (2009: 944), LDI is listed as Class II and Class III, which means evidence is supported by studies in which clearly reliable data is collected prospectively and/or retrospectively: such studies include observational studies, cohort studies, prevalence studies, and case-control studies for Class II and Class III evidence provided by clinical series, comparative studies, case reviews, case reports, and expert opinion. However, LDI is not without inherent limitations and technical difficulties including instrumental and pathophysiological causes such as the type of equipment used, scanning distance, curvature of tissues and appearance of the wound (Atiyeh, Gunn, & Hayek, 2005: 134). Despite technological advancements clinical assessment remains the most widely practiced method for burn wound depth estimation (Heimbach, Engrav, Grube, et al., 1992: 10 -15). Although more research is needed, LDI has brought technology closer to providing a reliable adjuvant to the clinical prediction of healing.

In light of this discussion, LDI appears to be the most accurate method of burn depth assessment. However, as these technologies are fairly new it is too early to provide strong levels of evidence at this stage. Furthermore is its feasibility in countries with limited financial resources like South Africa is questionable. To date it is not freely available or in use in clinical practice. Therefore, in the absence of LDI, clinical assessment will unfortunately have to suffice (Level V evidence).

Apart from the disagreement as to the methodology for measuring burn depth, the terminology used to describe the depth is also in dissensus. A variety of terms have been used to describe burn depth. In the past burn depth was described by degrees, specifically: first, second, third and fourth degree (Johnson in Richard & Staley, 1994: 29; Moncrief in Moncrief & Pruitt, 1979:23; Feller & Archambeault, 1973:5).

However, in recent literature there seems to be a shift in the terminology grounded on the anatomic thickness of the skin involved and is based on the increasing depth going from epidermal to

superficial partial thickness, deep partial thickness to full thickness burns (Devgan, et al., 2006: 7-15;

Watts, Tyler, Perry, et al., 2001:154).

And even more recently Monstrey, et al., (2008: 762), observed that burn depth is better defined by the time of healing which is linked to the risk of developing hypertrophic scarring; superficial wounds

144 healing by conservative treatment versus deep burn wound healing which requires surgical therapy. The variation in terminology can cause a variation in interpretation and miscommunication.

According to the criteria set out for inclusion in this review, the researcher included guidelines as the highest level of evidence. Guidelines are “systematically developed statements to assist practitioner

decisions about appropriate health care for specific clinical circumstances” (Thomas, 1999:2).

According to Thomas (1999:2), guidelines can be used to reduce inappropriate variations in practice and to promote the delivery of high quality, evidence-based health care; these may also provide a mechanism by which healthcare professionals can be held accountable for clinical activities.

The reviewed guidelines include the American Burn Association guidelines (2009: 11), which defines burn depth as epidermal (first-degree), partial-thickness (second-degree), or full-thickness (third-

degree). Burns extending beneath the subcutaneous tissues and involving fascia and/or muscle are

considered fourth-degree and burns causing such deep tissue destruction that they require amputation or loss of a body part, are termed fifth-degree. The Australian and New Zealand Burn Association (2007: 20), refer to burn depth according to anatomical structures involved, in other words epidermal,

superficial dermal, mid dermal, deep dermal and full thickness. The British Burn Association is

guided by the European Standards (2002), that clearly depicts the transition in terminology used to describe burn depth from first, second and third degree to the current epidermal, superficial partial

thickness, deep partial thickness, full thickness and full thickness plus. The South African Burn

Society (2012), defines burns as superficial, partial thickness or superficial dermal, partial thickness

deep or deep dermal and full thickness. The variation in terminology is more for theoretical value but,

due to the interconnectivity of health care professionals. It remains important that a form of standardisation exists so as to avoid misunderstanding.

The researcher noted that, although the different associations have guidelines in place, it could not be confirmed that the guidelines on burn depth were evidence informed as there is little reliable evidence on the assessment of burn depth and definitions used are solely from expert opinion. In the reviewed literature, no studies were found that validated the use of either terminology. Several articles were found using the different terminologies. However, all the literature consisted of essays. No randomised or non-randomised trials were found. The strength of evidence is, therefore, low as the choice of terminology is informed purely on the opinions of individuals. In view of this, the researcher decided to align herself with the most recent and frequently used terminology which is in line with the South African Burns Society (Level of evidence V).

On the other hand burn size reliability had been tested by Wachtel, Berry, Wachtel, et al., (2000), and will now be discussed as the second tier in burn wound classification.

145

Size (extent) of the burn

The extent of the burn refers to the total body surface area (TBSA) of injured tissue; calculated as a percentage of TBSA (Porth, 2011: 1190). The size of the burn is very important as it is used to establish the need for fluid resuscitation, the calculation of fluid requirements, nutritional support, evaluation of prognosis (in other words the morbidity and mortality) and monitoring the progress of healing (Miminas, 2007:58- 60; Wachtel, et al., 2000: 156; Scott-Conner, Coil, Conner, et al.,1986: 123-127; Zawacki , Azen, Imbus, et al., 1979: 1-5).To further understand the estimation of burn size, the methods of calculating the burn size will be expanded on.

Three methods of calculating the size of the burn are commonly discussed in the literature: Wallace

Rule of Nines, Lund & Browder and Palmar surface area. However, a fourth method which is not

typically mentioned in the literature is Berkow. According to Berkow (1924:148), the method for estimating the extensiveness of the burn in an adult, is founded on the ratio between the head, trunk, upper and lower extremities and the total body surface area; the lower extremities accounting for 38%, the trunk 38%, upper extremities 18% and the head 6%. Lund & Browder found that Berkow's tables were not applicable to all age groups as adult and paediatric body surface areas ratios differ (Lund & Browder, 1944:352- 358).

The Lund & Browder chart subdivides the body into segments and assigns a proportionate percentage to each area based on age, that is, it takes into account changes in the contribution of the head and legs from infancy to adulthood (Sheridan, 2012: 33; Lund & Browder, 1944:352- 358). For example a newborn baby’s head is proportionately larger than other parts of its body with the largest percentage allocated to its head. As the child grows the legs are allocated a bigger percentage with the head now being allocated a smaller proportion.

The Lund & Browder calculation method was followed by Wallace’s “Rule of Nines” (Wallace, 1951: 501-504). The Rule of Nines uses a rough estimate that assumes adult body proportions divide the body into seven areas that represent multiples of 9%. In other words, the head and neck are roughly 9%, the anterior and posterior chest are 9% each, the anterior and posterior abdomen are 9% each, each upper extremity is 9%, each thigh is 9%, each leg and foot is 9% and the remaining 1% represents the genitalia (Sheridan, 2012: 33; Watchel, et al., 2000:157; Wallace, 1951: 501-504).

The fourth method of calculation is the palmar surface of the hand (Sheridan, Petras, Basha, et al., 1995: 605-606). The palmar surface of the patient’s hand (without the fingers) is approximately 1% of their body surface over all age groups; visualizing the patient’s hand covering the burn wound

146 approximates the percentage of body surface area involved (Sheridan, 2012: 33; Butcher & Swales, 2012: 50; Sheridan, et al., 1995: 262).

According to Hettiaratchy & Papini (2004: 101), when calculating the burn size erythema should not be included; this might take a few hours and some size overestimation is inevitable if the burn is measured acutely. For this reason several studies advocate assessment of burns after 48 hours only (Chatterjee, 2006: 123; Hemington-Gorse, 2005: 151-153; Renkielska, Nowakowski, Kaczmark, et al., 2005: 768-775). However, the initial assessment can change after the initial oedema and inflammatory reaction have settled and could present as an increase in severity and depth over the first few days, particularly in areas of poor circulation or infection.

Whilst reviewing the literature, it was found that the American Burn Association uses the Rule of Nines to assess the size of the burn (American Burn Association referral criteria, 2006). The Australian and New Zealand Burn Association (2010:38), and the South African Burns Association (2012), advocate the use of the Lund & Browder chart, the European Burns Association (2002) also uses the Lund & Browder chart supplemented by the palmar surface method.

The evidence suggests that the Lund & Browder charts are more accurate than either the Rule of Nines or palm size in identifying TBSA (Hettiaratchy & Papini, 2004: 101). Inter-rater reliability refers to the ability of a chart to produce similar values of TBSA for the same patient when assessed by different individuals; if these values correlate for a number of patients, then the inter-rater reliability is high (Minimas, 2007: 62). Only one observational study was identified which aimed to assess inter-rater reliability of the Lund & Browder chart and this assessment concluded that the Lund & Browder chart was the most accurate method of assessing burn size (Wachtel, et al., 2000: 168). Estimates from the Rule of Nine's diagrams were the least precise and it was established that the use of charts based on the Rule of Nine's consistently led to a 3% larger burn estimate (Wachtel, et al., 2000: 166). In the Watchel, et al., (2000), study concurrent validity was not tested statistically. In contrast to the Watchel, et al., (2000), study a review by Miminas (2007:58- 60), evaluated the liability, concurrent and construct validity, acceptability and readability and weaknesses of the Lund & Browder chart. The review concluded that the importance in various aspects of the management of patients with burns, established primarily through the longevity of the instrument and its relative ease of use, cannot be underestimated.

However the age of the data upon which Lund & Browder is based and the flaws identified, especially in relation to the instruments suitability for everyone, raises issues that can only be resolved with the application of scientific principals and defined protocols both of which needed to be viewed by a team of experts in a more formal approach (Miminas, 2007).

147 No guidelines or systematic reviews were found on accuracy of the Rule of Nines assessment method. Five observational studies were found comparing the Rule of Nines burn area chart with other methods of estimating burn surface area. The Rule of Nines has been found to provide reasonable estimates for burned body surface area for most children and adults (Kanthraj, Srinivas, Shenoi, et al., 1997:922-923).

However the accuracy of this method decreased for obese patients. Livingston & Lee (2000: 106- 110), proposed that for obese patients or those weighing more than 80kg (BMI >30), a Rule of Fives be used. Furthermore, it was proposed that a modification to the Lund & Browder chart be used in larger breasted women as breast burns on these women could be underestimated by as much as 5% (Hidvegi, Nduka, Myers, et al., 2004: 1591- 1597).

The practice of using a person’s hand size to approximate 1% body area is a common method used for assessment of burn size, but this method has not been well validated (Amirsheybani, Crecelius, Timothy, et. al., 2001: 726-733; Berry, Evison & Roberts, 2001: 591-594; Perry, Moore, Morgan, et al., 2000: 1338; Nagel & Schunk, 1997: 254-255; Sheridan, et al., 1995: 605-606). Six studies were identified that explored the palmar surface method for determining the size of the burn with each study’s mean hand ratio to TBSA found to be around 0.8% (Agarwal & Sahu, 2010: 49-53; Amirsheybani, et. al., 2001: 726-733; Berry, et al., 2001: 591-594; Perry, et al., 2000: 1338; Nagel & Schunk, 1997: 254-255; Sheridan, et al., 1995: 605-606). Agarwal & Sahu (2010: 52), most recently concluded that palmar surface estimation might overestimate the size of the burn and was not an accurate assessment method.

From the above it is clear that Lund & Browder’s chart is the most accurate method to determine the size of the burn and is therefore the recommended method from this review (Level of evidence II). The next guiding question examines the assessment of burns at micro level, in other words, it takes a more intimate look at the burn wound.