- Email: [email protected]
Brooke formula revisited
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burns 40 (2014) 1813–1821
Mohsen Rezaeian* Epidemiologist Social Medicine Department, Occupational Environmental Research Center, Rafsanjan Medical School, Rafsanjan University of Medical Sciences, Rafsanjan, Iran *Tel.: +98 3915234003; fax: +98 03915225209 E-mail address: [email protected] (M. Rezaeian) http://dx.doi.org/10.1016/j.burns.2014.08.023 0305-4179/# 2014 Elsevier Ltd and ISBI. All rights reserved.
Letter to the Editor Brooke formula revisited Sir, Improvements of survival after major burns have come to a standstill following perceived improvement of outcome from the early days. The improved outcome from burns can be attributed partly to the development of fluid resuscitation formulas in 1950s: Evans’ formula (1952), Brooke formula (1953). During 1943–1947 period 69% of total burn deaths occurred within first 48 h; this dropped sharply to 19% during 1952–1956 periods [1]. By this time Evans’ and Brooke formula alone were in use but not Parkland formula. Muir and Barclay formula and Parkland formula were introduced later in 1962 and 1968, respectively. Therefore it is quite clear that Evans’ and Brooke formulae, which use both colloids and crystalloids, were able to reduce burn deaths significantly. However the commonly practised fluid regime today is Parkland formula which uses crystalloids alone during the first 24 h. Brooke formula is almost never used. Have we achieved anything significant by shifting from Brooke to Parkland formula? The answer is probably ‘no’ because the mortality from burns is still as high as 34% in certain centres [2]. If there is any improvement of outcome in recent years this is because of the improvement of other modalities of management such as better intensive care, antibiotics, nutrition, wound care techniques etc. rather than the use of Parkland formula. Despite its unpopularity, Brooke formula seems to have many advantages over Parkland formula. Altogether Brooke formula uses 50% less fluid (1.5 mL/kg/%TBSA crystalloids +0.5 mL/kg/%TBSA colloids in first 24 h) than Parkland formula (4 mL/kg/%TBSA crystalloids in first 24 h). This has beneficial effects on limiting ‘resuscitation morbidity’, which include infective complications, compartment syndromes, ARDS and death. Secondly original Brooke formula uses colloids from the beginning of resuscitation; Parkland formula does not. When looked in to the pathophysiology of development of burn oedema and shock it is clear that the leakage of plasma proteins plays a prominent role as a result of increased capillary permeability. The protein loss starts soon (2 h) after the burn [3]. Intravascular hypovolemia and haemoconcentration reach to maximum levels within 12 h of injury [4], and persists for at least 24 h. The time at which the increased
protein leak stops has been variably assigned ranging from 5 to 24 h [4]. Recent studies have shown beneficial effects of giving less fluid and some colloids in burn resuscitation. Chung et al. found that using less fluid as estimated by modified Brooke formula (2 mL/kg/%TBSA) was not associated with any increase of morbidity or mortality when compared with giving more fluid using Parkland formula [5]. Cochrane et al. report decreased mortality when albumin is used in resuscitation of burns [6]. Atiyeh et al. also report the beneficial effects of colloids in limiting fluid creep [7]. O’Mara et al. demonstrated decreased overall fluid volumes and lower intra-abdominal pressures when fresh frozen plasma was used instead of crystalloids for resuscitation [8]. Therefore despite its unpopularity it looks like that the original Brooke formula does have a place in burn resuscitation. Parkland formula (4 mL/kg/%TBSA) uses only crystalloids and the volume also is as twice as the volume of Brooke formula. Giving both sodium and plasma proteins in moderation (Brooke formula) theoretically have advantages. The theoretical evidence comes from the research of Charles Baxter, who developed Parkland formula, itself. (1) Baxter found that the fluid leaking from the capillaries into the interstitial space after burns have a protein composition similar to that of plasma. Therefore leakage of proteins is a significant event in burns. This causes development of increased oncotic pressure in the interstitial space and the reduction of the same in the intravascular space. This shift of plasma proteins, therefore, promotes leakage of water from the intravascular space into the interstitial space contributing to development of oedema. However, colloids were not recommended during the first 24 h by Baxter because he thought supplemental proteins would leak into the interstitial space causing more oedema. (2) Another great discovery of Baxter and Shires was the concept of ‘‘cellular shock’’. The burn has systemic effects on the membrane associated ion channels leading to accumulation of sodium within the cells resulting in decreased transmembrane potential and increasing cellular oedema. Therefore the oedema would continue to build up when more fluid is given in the form of water and sodium. This is actually the case observed by many researchers recently in the form of ‘fluid creep’. When crystalloids alone are given the actual volume that goes to the patient to maintain urine output exceeds the volume estimated by either modified Brooke or Parkland formula (3.8 mL/kg/ %TBSA and 5.9 mL/kg/%TBSA, respectively, as opposed to the recommended 2 and 4 mL/kg/%TBSA, respectively) [5]. From the above facts it is evident that there was a discrepancy in thoughts of Baxter when colloids were not advised in early burn resuscitation. Noticing that there was leakage of plasma proteins it was advised to avoid plasma. But by noticing sodium leak into cells it was not advised to limit sodium and water. Therefore, it is irrational to use crystalloids generously and avoid colloids altogether during the first 24 h. C.P. Artz from the Army Burn Center in San Antonio devised the Brooke formula in 1953 as a modified version of Evans’ formula putting more emphasis on crystalloid resuscitation and less emphasis on colloid resuscitation [9]. Everett Idris Evans, in
burns 40 (2014) 1813–1821
1952, was the first to devise a burn resuscitation protocol based on TBSA burned and the body weight. The general agreement in his time was that the principle cause of burn shock was loss of circulating plasma and red cell components into the burn zone. Based on this Evans proposed to give normal saline at 1 mL/kg/% burn + colloids at 1 mL/kg/% burn + plus 2000 mL glucose in water in first 24 h: In second 24 h: one-half the first 24 h crystalloid and colloid requirements + the same amount of glucose in water as in the first 24 h. This formula was usefully applied in practice by many getting better results. In Artz’s modification he advocated to give a little more crystalloids and less colloids as follows: normal saline at 1.5 mL/kg/% burn + colloids at 0.5 mL/kg/% burn + plus 2000 mL glucose in water in first 24 h: In second 24 h: one-half the first 24 h crystalloid and colloid requirements + the same amount of glucose in water as in the first 24 h. The basis of this change by Artz was his observation that water and electrolytes lose into the burn wound at a greater rate than proteins do. The total volume of Brooke formula is as same as the total volume of Evans’ formula but the composition is slightly different. At a glance Brooke formula is impressive because it addresses both effects of leaking proteins into the interstitium and shifting sodium into the cells by giving both plasma and sodium. Most importantly Brooke formula limits crystalloids infusion, which is absent in Parkland formula, limiting development of cellular oedema. It also meets the recommendations of Baxter to limit colloids by giving colloids in moderate amounts. Please note that Brooke formula does not totally replenish the proteins that are lost in burns. The amount of plasma that is given in Brooke formula is much less than the amount of plasma lost in burns. The rate of plasma loss is 4 mL/ kg/h in a burn exceeding 30% TBSA [10]. Accordingly, a 75 kg man with 30% burns would lose 7200 mL of plasma in 24 h. In Brooke formula the rate of plasma infusion for a 30% burn in a 75 kg man is only 1125 mL in 24 h. This is much less (only 15% of the lost) than the total amount of plasma that the patient loses in first 24 h. Therefore although colloids are given in Brooke formula the idea is not to replenish all the lost plasma but to cautiously maintain a fine balance between the plasma oncotic pressure and interstitial oncotic pressure so that the development of interstitial and cellular oedema can be minimized. Not only Brooke and Evans’ formulas but also several other formulas recommend giving both crystalloids and colloids during the first 24 h. These include: 1. Slater formula: lactated Ringers 2000 mL plus fresh-frozen plasma at 75 mL/kg/24 h 2. Haifa formula: plasma at 1.5 mL/kg/% TBSA burn plus lactated Ringer’s at 1 mL/kg/% TBSA burn 3. Demling formula: Dextran40 in normal saline at 2 mL/kg/h for 8 h. Fresh-frozen plasma at 0.5 mL/kg/h starting at 8 h. Lactated Ringer’s should be given to maintain urine output.
1819
By looking at above formulas it is clear that Brooke formula has a fair balance of both crystalloids and colloids to partly replenish both plasma and sodium yet avoiding overtransfusion of the same. It replaces plasma cautiously. Brooke formula uses much less (only 37.5%) crystalloids than Parkland formula. Therefore Brooke formula seems to meet the physiological requirements in burn patients better.
Conflict of interest statement The author declares that there is no conflict of interest.
references
[1] Clark AG, Hanson JH. Mortality rates in patients with burns. Calif Med 1958;89(3):210–4. [2] Brusselaers N, Monstrey S, Vogelaers D, Hoste E, Blot S. Severe burn injury in Europe: a systematic review of the incidence, aetiology, morbidity, and mortality. Crit Care 2010;14(5):R188. [3] Vlachou E, Gosling P, Moiemen NS. Microalbuminuria: a marker of endothelial dysfunction in thermal injury. Burns 2006;32:1009–16. [4] Haberal M, Abali ES, Karakayali H. Fluid management in major burn injuries. Indian J Plast Surg 2010;43(1):29–36. [5] Chung KK, Wolf SE, Cancio LC, Alvarado R, Jones JA, McCorcle J, et al. Resuscitation of severely burned military casualties: fluid begets more fluid. J Trauma 2009;67:231–7. [6] Cochran A, Morris SE, Edelman LS, Saffle JR. Burn patient characteristics and outcome following resuscitation with albumin. Burns 2007;33(1):25–30. [7] Atiyeh BS, Dibo SA, Zgheib ER. Acute burn resuscitation and fluid creep: it is time for colloid rehabilitation. Ann Burns Fire Disasters 2012;25(2):59–65. [8] O0 Mara MS, Slater H, Goldfalb W, Caushaj PF. A prospective, randomized evaluation of intra-abdominal pressures with crystalloid and colloid resuscitation in burn patients. J Trauma 2005;58:1011–8. [9] Evans EI, Purnell OJ, Robinett PW, Batchelor A, Martin M. Fluid and electrolyte requirements in severe burns. Ann Surg 1952;135(6):804–17. [10] Ibrahim AE, Sarhane KA, Goverman J. Renal dysfunction in burns: a review. Ann Burns Fire Disasters 2013;26(1):16–25.
B. Sri Harsha Indrasena* Kandy General Hospial (Teaching), Sri Lanka *Correspondence to: No. 529, Balagolla, Kengalla 20186, Sri Lanka. Tel.: +94 0718713457 E-mail address: [email protected] (B.S.H. Indrasena) http://dx.doi.org/10.1016/j.burns.2014.09.016 0305-4179/# 2014 Elsevier Ltd and ISBI. All rights reserved.
burns 40 (2014) 1813–1821
Mohsen Rezaeian* Epidemiologist Social Medicine Department, Occupational Environmental Research Center, Rafsanjan Medical School, Rafsanjan University of Medical Sciences, Rafsanjan, Iran *Tel.: +98 3915234003; fax: +98 03915225209 E-mail address: [email protected] (M. Rezaeian) http://dx.doi.org/10.1016/j.burns.2014.08.023 0305-4179/# 2014 Elsevier Ltd and ISBI. All rights reserved.
Letter to the Editor Brooke formula revisited Sir, Improvements of survival after major burns have come to a standstill following perceived improvement of outcome from the early days. The improved outcome from burns can be attributed partly to the development of fluid resuscitation formulas in 1950s: Evans’ formula (1952), Brooke formula (1953). During 1943–1947 period 69% of total burn deaths occurred within first 48 h; this dropped sharply to 19% during 1952–1956 periods [1]. By this time Evans’ and Brooke formula alone were in use but not Parkland formula. Muir and Barclay formula and Parkland formula were introduced later in 1962 and 1968, respectively. Therefore it is quite clear that Evans’ and Brooke formulae, which use both colloids and crystalloids, were able to reduce burn deaths significantly. However the commonly practised fluid regime today is Parkland formula which uses crystalloids alone during the first 24 h. Brooke formula is almost never used. Have we achieved anything significant by shifting from Brooke to Parkland formula? The answer is probably ‘no’ because the mortality from burns is still as high as 34% in certain centres [2]. If there is any improvement of outcome in recent years this is because of the improvement of other modalities of management such as better intensive care, antibiotics, nutrition, wound care techniques etc. rather than the use of Parkland formula. Despite its unpopularity, Brooke formula seems to have many advantages over Parkland formula. Altogether Brooke formula uses 50% less fluid (1.5 mL/kg/%TBSA crystalloids +0.5 mL/kg/%TBSA colloids in first 24 h) than Parkland formula (4 mL/kg/%TBSA crystalloids in first 24 h). This has beneficial effects on limiting ‘resuscitation morbidity’, which include infective complications, compartment syndromes, ARDS and death. Secondly original Brooke formula uses colloids from the beginning of resuscitation; Parkland formula does not. When looked in to the pathophysiology of development of burn oedema and shock it is clear that the leakage of plasma proteins plays a prominent role as a result of increased capillary permeability. The protein loss starts soon (2 h) after the burn [3]. Intravascular hypovolemia and haemoconcentration reach to maximum levels within 12 h of injury [4], and persists for at least 24 h. The time at which the increased
protein leak stops has been variably assigned ranging from 5 to 24 h [4]. Recent studies have shown beneficial effects of giving less fluid and some colloids in burn resuscitation. Chung et al. found that using less fluid as estimated by modified Brooke formula (2 mL/kg/%TBSA) was not associated with any increase of morbidity or mortality when compared with giving more fluid using Parkland formula [5]. Cochrane et al. report decreased mortality when albumin is used in resuscitation of burns [6]. Atiyeh et al. also report the beneficial effects of colloids in limiting fluid creep [7]. O’Mara et al. demonstrated decreased overall fluid volumes and lower intra-abdominal pressures when fresh frozen plasma was used instead of crystalloids for resuscitation [8]. Therefore despite its unpopularity it looks like that the original Brooke formula does have a place in burn resuscitation. Parkland formula (4 mL/kg/%TBSA) uses only crystalloids and the volume also is as twice as the volume of Brooke formula. Giving both sodium and plasma proteins in moderation (Brooke formula) theoretically have advantages. The theoretical evidence comes from the research of Charles Baxter, who developed Parkland formula, itself. (1) Baxter found that the fluid leaking from the capillaries into the interstitial space after burns have a protein composition similar to that of plasma. Therefore leakage of proteins is a significant event in burns. This causes development of increased oncotic pressure in the interstitial space and the reduction of the same in the intravascular space. This shift of plasma proteins, therefore, promotes leakage of water from the intravascular space into the interstitial space contributing to development of oedema. However, colloids were not recommended during the first 24 h by Baxter because he thought supplemental proteins would leak into the interstitial space causing more oedema. (2) Another great discovery of Baxter and Shires was the concept of ‘‘cellular shock’’. The burn has systemic effects on the membrane associated ion channels leading to accumulation of sodium within the cells resulting in decreased transmembrane potential and increasing cellular oedema. Therefore the oedema would continue to build up when more fluid is given in the form of water and sodium. This is actually the case observed by many researchers recently in the form of ‘fluid creep’. When crystalloids alone are given the actual volume that goes to the patient to maintain urine output exceeds the volume estimated by either modified Brooke or Parkland formula (3.8 mL/kg/ %TBSA and 5.9 mL/kg/%TBSA, respectively, as opposed to the recommended 2 and 4 mL/kg/%TBSA, respectively) [5]. From the above facts it is evident that there was a discrepancy in thoughts of Baxter when colloids were not advised in early burn resuscitation. Noticing that there was leakage of plasma proteins it was advised to avoid plasma. But by noticing sodium leak into cells it was not advised to limit sodium and water. Therefore, it is irrational to use crystalloids generously and avoid colloids altogether during the first 24 h. C.P. Artz from the Army Burn Center in San Antonio devised the Brooke formula in 1953 as a modified version of Evans’ formula putting more emphasis on crystalloid resuscitation and less emphasis on colloid resuscitation [9]. Everett Idris Evans, in
burns 40 (2014) 1813–1821
1952, was the first to devise a burn resuscitation protocol based on TBSA burned and the body weight. The general agreement in his time was that the principle cause of burn shock was loss of circulating plasma and red cell components into the burn zone. Based on this Evans proposed to give normal saline at 1 mL/kg/% burn + colloids at 1 mL/kg/% burn + plus 2000 mL glucose in water in first 24 h: In second 24 h: one-half the first 24 h crystalloid and colloid requirements + the same amount of glucose in water as in the first 24 h. This formula was usefully applied in practice by many getting better results. In Artz’s modification he advocated to give a little more crystalloids and less colloids as follows: normal saline at 1.5 mL/kg/% burn + colloids at 0.5 mL/kg/% burn + plus 2000 mL glucose in water in first 24 h: In second 24 h: one-half the first 24 h crystalloid and colloid requirements + the same amount of glucose in water as in the first 24 h. The basis of this change by Artz was his observation that water and electrolytes lose into the burn wound at a greater rate than proteins do. The total volume of Brooke formula is as same as the total volume of Evans’ formula but the composition is slightly different. At a glance Brooke formula is impressive because it addresses both effects of leaking proteins into the interstitium and shifting sodium into the cells by giving both plasma and sodium. Most importantly Brooke formula limits crystalloids infusion, which is absent in Parkland formula, limiting development of cellular oedema. It also meets the recommendations of Baxter to limit colloids by giving colloids in moderate amounts. Please note that Brooke formula does not totally replenish the proteins that are lost in burns. The amount of plasma that is given in Brooke formula is much less than the amount of plasma lost in burns. The rate of plasma loss is 4 mL/ kg/h in a burn exceeding 30% TBSA [10]. Accordingly, a 75 kg man with 30% burns would lose 7200 mL of plasma in 24 h. In Brooke formula the rate of plasma infusion for a 30% burn in a 75 kg man is only 1125 mL in 24 h. This is much less (only 15% of the lost) than the total amount of plasma that the patient loses in first 24 h. Therefore although colloids are given in Brooke formula the idea is not to replenish all the lost plasma but to cautiously maintain a fine balance between the plasma oncotic pressure and interstitial oncotic pressure so that the development of interstitial and cellular oedema can be minimized. Not only Brooke and Evans’ formulas but also several other formulas recommend giving both crystalloids and colloids during the first 24 h. These include: 1. Slater formula: lactated Ringers 2000 mL plus fresh-frozen plasma at 75 mL/kg/24 h 2. Haifa formula: plasma at 1.5 mL/kg/% TBSA burn plus lactated Ringer’s at 1 mL/kg/% TBSA burn 3. Demling formula: Dextran40 in normal saline at 2 mL/kg/h for 8 h. Fresh-frozen plasma at 0.5 mL/kg/h starting at 8 h. Lactated Ringer’s should be given to maintain urine output.
1819
By looking at above formulas it is clear that Brooke formula has a fair balance of both crystalloids and colloids to partly replenish both plasma and sodium yet avoiding overtransfusion of the same. It replaces plasma cautiously. Brooke formula uses much less (only 37.5%) crystalloids than Parkland formula. Therefore Brooke formula seems to meet the physiological requirements in burn patients better.
Conflict of interest statement The author declares that there is no conflict of interest.
references
[1] Clark AG, Hanson JH. Mortality rates in patients with burns. Calif Med 1958;89(3):210–4. [2] Brusselaers N, Monstrey S, Vogelaers D, Hoste E, Blot S. Severe burn injury in Europe: a systematic review of the incidence, aetiology, morbidity, and mortality. Crit Care 2010;14(5):R188. [3] Vlachou E, Gosling P, Moiemen NS. Microalbuminuria: a marker of endothelial dysfunction in thermal injury. Burns 2006;32:1009–16. [4] Haberal M, Abali ES, Karakayali H. Fluid management in major burn injuries. Indian J Plast Surg 2010;43(1):29–36. [5] Chung KK, Wolf SE, Cancio LC, Alvarado R, Jones JA, McCorcle J, et al. Resuscitation of severely burned military casualties: fluid begets more fluid. J Trauma 2009;67:231–7. [6] Cochran A, Morris SE, Edelman LS, Saffle JR. Burn patient characteristics and outcome following resuscitation with albumin. Burns 2007;33(1):25–30. [7] Atiyeh BS, Dibo SA, Zgheib ER. Acute burn resuscitation and fluid creep: it is time for colloid rehabilitation. Ann Burns Fire Disasters 2012;25(2):59–65. [8] O0 Mara MS, Slater H, Goldfalb W, Caushaj PF. A prospective, randomized evaluation of intra-abdominal pressures with crystalloid and colloid resuscitation in burn patients. J Trauma 2005;58:1011–8. [9] Evans EI, Purnell OJ, Robinett PW, Batchelor A, Martin M. Fluid and electrolyte requirements in severe burns. Ann Surg 1952;135(6):804–17. [10] Ibrahim AE, Sarhane KA, Goverman J. Renal dysfunction in burns: a review. Ann Burns Fire Disasters 2013;26(1):16–25.
B. Sri Harsha Indrasena* Kandy General Hospial (Teaching), Sri Lanka *Correspondence to: No. 529, Balagolla, Kengalla 20186, Sri Lanka. Tel.: +94 0718713457 E-mail address: [email protected] (B.S.H. Indrasena) http://dx.doi.org/10.1016/j.burns.2014.09.016 0305-4179/# 2014 Elsevier Ltd and ISBI. All rights reserved.