|Year : 2021 | Volume
| Issue : 2 | Page : 103-109
Fluid resuscitation in adult burns
Ashish Kumar Gupta, Ebenezer Asirvatham, Komala Abhishek Reddy, Shashank Lamba
Department of Plastic Surgery, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Submission||13-Oct-2020|
|Date of Decision||20-Nov-2020|
|Date of Acceptance||15-Dec-2020|
|Date of Web Publication||15-Apr-2021|
Dr. Shashank Lamba
Department of Plastic and Reconstructive Surgery, Unit II, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Fluid replacement is an integral part of adult burn care, especially in patients with more than 20% total body surface area involvement. The fluid loss in burns has to be adequately replaced to maintain satisfactory tissue perfusion and prevent shock. Over these years, many different formulas and a variety of fluids have been used to resuscitate these patients. This article reviews the current trends and different approaches in fluid management.
Keywords: Brooke, burns, colloid, crystalloid, fluid resuscitation, parkland
|How to cite this article:|
Gupta AK, Asirvatham E, Reddy KA, Lamba S. Fluid resuscitation in adult burns. Curr Med Issues 2021;19:103-9
| Introduction|| |
The three landmark interventions that have decreased mortality in the acute phase of major burns are the three Fs – Fluids, Feeding, and Fillet (emergent surgery). Numerous formulas developed after the Cocoanut Grove Night Club fire of 1942 have significantly decreased the mortality and morbidity of burn shock. The main aim of fluid resuscitation is to give the minimum amount of fluid to maintain adequate urine output and simultaneously avoid the complication of both underperfusion or overperfusion.
The modern formulas were intended to decrease chances of oliguria, acute renal failure, and increase in burn percentage and depth due to under-resuscitation. Over time, the under-resuscitation problem was replaced by over-resuscitation.
Pruitt formulated the term “fluid creep” to describe the problem of over-resuscitation. Several strategies have been described to avoid over-resuscitation. Fluid resuscitation has moved full circle from insufficient to over the top and is now returning to adequate.
| Fluid Resuscitation|| |
Burns more than 20%–25% total body surface area (TBSA) are associated with a systemic response, causing an increased capillary leak in burned and nonburned regions making them prone to shock. These changes are more profound during the first 24 h. This leakage allows protein transudation from the intravascular compartment into the interstitial compartment which decreases the oncotic pressure in the intravascular compartment causing additional loss of fluid into the interstitial space. However, capillary permeability is significantly decreased in nonburned regions after 8–12 h. The quantum of edema is also be influenced by the quantity and type of fluid infused. Due to the above-mentioned reasons, intravenous fluid resuscitation is recommended in all adult burns exceeding more than 20% TBSA.
| Prehospital Fluid Management|| |
The early fluid requirement in burns differs from other types of trauma in which it develops slowly in comparison to massive hemorrhage. Prehospital intravenous fluid is indicated for burns more than 25% TBSA or in cases of delay of more than 1 h in shifting the patient to the hospital. However, establishing intravenous access must not delay the transport of the major burn patient.
As per the American Burn Association (ABA), the starting rate of RL can be calculated by:
Adults (40–80 Kg): TBSA × Weight (Kg)/8 = Rate (ml/h)
or by Rule of Ten (for adults weighing 40–80 Kg)–
Estimate burn size to nearest 10
TBSA ×10 = Rate in ml/hr.
For every 10 Kg, above 80 kg add 100 ml/h.
The Rule of Ten is the easiest to use as it includes only two variables in comparison to Modified Brooke's Formula (MBF) or Parkland Formula (PLF). On the other hand, MBF should be preferred over the Parkland (PLF) in calculating the starting rate.
In resource-poor countries, oral rehydration solution can be used to resuscitate burns up to 40% TBSA. The burn patient should be advised to drink approximately 50 mL every 5 min, with the aim of a liter per hour.
| Formulas for Fluid Resuscitation|| |
Multiple formulas have been devised to calculate fluid requirements in acute burn care [Table 1]. The first few formulas used only the burn size for calculation of fluid. Later, both the Evans' (1952) and Brooke's Formula (1953) used the size of burns and weight of the patient. These formulas eliminated the complication of acute renal failure due to inadequate fluid volume. They both used crystalloids and colloids in the ratio of 1:1 and 3:1, respectively.
|Table 1: List of commonly used resuscitation formulae with composition during the 1st and 2nd days|
Click here to view
The MBF recommended Ringer's Lactate (RL) at 2 ml/kg/% TBSA burns during the initial 24 h. In the following 24 h, the crystalloid is discontinued and the colloid is introduced at the rate of 0.3–0.5 ml/Kg/% TBSA. Among all of these formulae, the PLF is the most preferred because it is simple, safe, and least expensive. It recommends RL at a rate of 4 ml/kg/% TBSA burns during the first 24 h and colloids during the beginning of the second day.
ABA in 2008 published a consensus formula on fluid management for the first 24 h which recommends RL 2–4 ml/Kg/%TBSA burns incorporating both PLF and MBF. It suggests that fluid resuscitation should be started with 2 ml/Kg/% burns and if required, increased gradually.,
Monafo and Warden used hypertonic saline (HTS) for fluid resuscitation., The main advantage of HTS is its ability to rapidly move water from intracellular space to extracellular space which increases the intravascular volume. Warden recommends the use of RL with 50 mEq sodium during the first 8 h, whereas the Monafo formula uses a solution with 250 mEq sodium, 150 mEq lactate, and 100 mEq chloride for 24 h.
HTS therapy demands careful monitoring and has a much narrow therapeutic margin than the crystalloid. This therapy is to be used by an experienced physician with monitoring of plasma sodium measurements.
Demling recommended dextran 40 for resuscitation during the first 24 h. He has used dextran 40 for the first 8 h at a rate of 2 ml/kg/h with RL to maintain a urine output of 30 ml/h. After 8 h, fresh frozen plasma (FFP) at the rate of 0.5–1.0 ml/kg/% TBSA burn is started along with RL over the next 16 h.
The recently described Haifa formula used crystalloid RL 1 ml/Kg/% TBSA and plasma 1.5 ml/Kg/% TBSA in the first 24 h.
| Which is the Best Formula?|| |
The experts have no consensus on which formula or which fluid is the best. However, there is an agreement on two important principles. First, the minimum amount of fluid required to maintain organ perfusion should be used. Second, the fluid infused should be continuously titrated to avoid both under- and overperfusion. Most centers titrate fluid with urine output and clinical signs. A urine output of 0.5 ml/kg/h is considered adequate in adults. The fluid resuscitation formulas are useful as starting guidelines and not absolute protocols for resuscitation in burn shock. Burn depth, inhalation injury, patient age, delays in resuscitation, and increased opioid analgesics may increase fluid requirements during burn resuscitation.
The most common formula used in the world is the PLF (among 70% burn units). Seventy-eight percent of all units use the PLF in the UK.,
All the formulas can be divided into four categories depending on the fluid chosen for day 1:
- Mixed crystalloid and colloid formulas – Evan, Brooke, and Haifa formula
- Crystalloid only formulas – Modified Brooke and Parkland
- HTS Formulas – Monafo and Warden formula
- Dextran based-Demling Formula.
| Crystalloid-alone Resuscitation|| |
The advocates of crystalloid-alone resuscitation claim that crystalloids are inexpensive, easily available, and time tested. Safety and cost are very important from the perspective of health policy. The reasons for using only RL and not RL with colloid during the first 24 h are as follows: First, the fluid leaving the intravascular space is isotonic relative to plasma and second, capillary permeability in burned tissue remains high for more than 24 h.
RL is the most commonly used crystalloid. It is slightly hypotonic and contains 130 mEq/L sodium and 4 mEq of potassium. The lactate in RL is metabolized to bicarbonate; thus, the solution becomes alkaline in situ. This helps to decrease the chances of lactic acidosis that accompanies burn injuries. The composition of RL is also very similar to plasma and effectively corrects both hypovolemia and the extracellular sodium deficit.
Normal saline is not used in fluid resuscitation because in large volumes, it can cause hyperchloremic acidosis. The PLF is associated with extensive loss of fluid into the interstitial space. It has been found that after 30 min of crystalloid infusion only 16% of crystalloid stays in the intravascular compartment and thus worsens edema.
| Colloid in Burns Fluid Resuscitation|| |
The role of colloid is controversial in acute burn resuscitation. Supporters of colloid argue that colloids remain in the intravascular space longer, require less volume for shock correction, and cause less tissue edema.
In 1979, the NIH-sponsored conference on burn care did not include the use of colloid in the consensus statement. They suggested that the PLF only predicts fluid requirement for initial 24 h, without the use of plasma in the second 24 h. The use of colloids was dramatically decreased after the Cochrane injury group publication on the role of albumin in 1998 which inferred that there is no proof of reduction in mortality by the use of albumin in critically ill patients and suggested that it may on the other hand, increase it. Many centers have removed the plasma component from the original PLF.
| Type of Colloids|| |
Colloids used in burns are of two types: synthetic and biological. Some examples of synthetic colloids are hydroxyethyl starch solutions, gelatins, and dextran. Among biological colloids, FFP was originally used as a plasma expander. Parenteral human albumin (HA) is nowadays the most commonly used colloid in burns. HA is available as a 5% and 20% solution.
Third-generation starches can be used in resource-poor countries in a desperate situation because current evidence is not enough to avoid their use in burns., At the moment, colloids are expensive and they have not clearly proven better than the isotonic crystalloids.
| Colloid Timing|| |
At present, there are three approaches: (1) no colloids during the first 24 h, (2) colloids during the first 24 h, (3) and colloids after 24 h.
Baxter recommended plasma during the fourth 8-hr period. Recent surveys showed that an increasing number of clinicians have included colloids during the first 24 h.,
| Indications of Colloid Use|| |
Chung used 5% albumin in patients whose 24-h projected fluid requirement exceeds 6 ml/Kg/%TBSA. Another indication for colloid infusion is when albumin levels are below 1.2–1.5 g/dl.,
| Fluid Rate|| |
The initial step in fluid resuscitation is the calculation of burn size by using Rule of Nines, Lund–Browder Chart, and Rule of Palm. In the burns' unit, the size should be calculated by Lund–Browder Chart because Rule of Nines often overestimates burn size. Overestimation of burn size will overestimate the fluid requirement. It is important to note that only second- and third-degree burns are included for the calculation of fluids.
The second step is the calculation of fluid by some formula. Fifty percent of the calculated fluid is infused in the first 8 h and the rest in the remaining 16 h. ABA recommends starting fluid at 2 ml/kg/% TBSA. Research has shown that if resuscitation is begun at 4 ml/kg/%TBSA, then patients will need more fluid.
Example: An adult with 50% TBSA burns who weighs 60 kg will require:
2 ml RL × 60(Kg) × 50 (% TBSA) = 6000 ml RL in the first 24 h.
3000 ml (half) is infused in the first 8 h and the remaining 3000 ml in the remaining 16 h.
The fluid requirement is calculated from the time of injury rather than the time of starting fluids, for example, if fluid resuscitation is delayed by 2 h, then fluid calculated for the first 8 h should be infused in the next 6 h. If fluid resuscitation is delayed by more than 6 h, then the most appropriate approach for catch up fluid should be discussed with burns clinician. Bolus infusion should be avoided.
The third step is the titration of fluid and monitoring. The formula only provides the starting rate. Volume infused should always be titrated and adjusted as per the patient response. Rigid adherence to the formula is counterproductive. The mantra to avoid over- or under-resuscitation is titrate, titrate, and titrate. It is easier to give more fluid during resuscitation than remove excess fluid. The most readily available and reliable method to judge the adequacy of fluid resuscitation is by measuring urine output with an indwelling catheter. The optimal urine output that has been suggested in the adult is 0.3–0.5 ml/kg/hr. Urine outputs below these level within the first 48 h almost always represent inadequate fluid resuscitation. Recently, computer programs are used to adjust the fluid infusion rates to urine output every 10 min or less. Both PLF and MBF recommend a sudden reduction in the fluid by 50% at the end of the 8th h. This sudden reduction is ill advised. Fluid should be slowly decreased.
Many protocols are described to adjust the fluid rate as per urine output and simple clinical parameters [Figure 1].
Traditional markers of successful resuscitation such as urine output, pulse rate, and blood pressure may lead to suboptimal resuscitation and are now questioned. Suboptimal fluid resuscitation prolongs the period of shock and can increases burn depth. An increasing number of studies are published on the role of invasive monitoring in burn shock. Invasive monitoring includes central venous pressure measurement, transesophageal echocardiogram, and pulmonary artery catheterization. Most of the centers providing burn care are not equipped for invasive monitoring. A recent meta-analysis showed lower mortality in the invasive monitoring group compared to the noninvasive group, but the difference was not significant. Invasive hemodynamic monitoring is of value in selected high-risk patients.
| Second Day Fluid Management|| |
Evans, Brooke, Modified Brooke, and PLFs have described fluid management for the full 48 h. At present, fluid resuscitation is considered complete if the urine output is maintained on the calculated maintenance rate for 2 h and the patient is no <24 h post burn. Then, they are started on maintenance fluid.
Maintenance fluid in burns is calculated by normal maintenance fluid plus evaporative loss from the burned skin using the following formula:
(1500 ml × BSA) + (25 + %TBSA) × BSA × 24 = Maintenance fluid in 24 h.
Maintenance fluid can be given by either intravenous route (D5/0.45 NaCl + 20 mEq KCl/liter) or with enteral feeds.
| Fluid Creep and Over-Resuscitation|| |
Modern formulas almost eliminate acute renal failure, but the complication of underperfusion got replaced by overperfusion. Baxter reported that more than 79% of adults were favorably resuscitated with 3.7–4.3 mL/kg/% TBSA of RL. He also claimed that in 70% of adult patients, the formula was accurate, 18% required less, and 12% required more fluid.
He identified the group of patients who regularly required more fluids – like patients with inhalation burn injuries and electrical injuries and those who received delayed resuscitation. Later, two more conditions were added, patients requiring a large dose of opioid and alcohol abuse. Recent publications have reported fluid creep in 30%–80% of patients. The complications of over-resuscitation are extremity compartment syndromes, swelling in the face and airway, abdominal compartmental syndrome, pleural effusions, increased intraocular pressure, and respiratory and cardiac failure. Abdominal compartment syndrome, the most dreadful complication of over-resuscitation, is associated with a mortality rate of 78%. Fluid requirements usually are fairly close to formulas during the first 8–12 h. Increasing fluid requirements over and above the predicted fluid values may be appropriate in few patients with large burns. However, if fluid requirement continues to rise after this time, one should be alert about the clinical chance of fluid creep. Due to all these issues, monitoring of bladder pressure in patients who require resuscitation volumes above 6 ml/kg/%TBSA or Ivy Index of 250 ml/kg should be made a routine.
| Causes of Fluid Creep|| |
Several reasons have been suggested for fluid creep like overestimation of the burn size, overzealous prehospital fluid administration, failure to meticulously titrate fluid volume to urine output, excessive use of opioids, and goal-directed resuscitation.
Overestimation of burn size can significantly increase the fluid requirement, especially if PLF is used for fluid estimation. Chung et al. found that patients who started on PLF required more fluid than patients who started on MBF. They concluded, “Fluid begets more fluid.”
The use of fluid boluses also adds to the increased fluid during the early period of resuscitation. Saffle suggested that the modern clinician is not aggressively titrating fluid to urine output. According to him, the aim is to keep urine output close to 0.5 ml/h and does not allow it to go beyond 1 ml/h. ISBI Practice Guidelines for Burn Care (2016) recommend a urine output in the range of 0.3–0.5 ml h. Cancio et al. found that clinicians were reluctant to reduce fluid infusion if urine output is high. The use of a high dose of opioid agonist blunts the response to fluid infusion because of the vasodilatory effect of opioids., The goal-directed resuscitation using four times more fluid volume by intensive care specialist has not proved better than traditional resuscitation and is associated with fluid creep and abdominal compartment syndrome. Many strategies are suggested to prevent fluid creep like starting fluid resuscitation with small volume, titration of fluid to urine output using algorithms or computer program, use of colloid as rescue, Vitamin C infusion, and plasmapheresis.
| Adjuncts to Resuscitation|| |
Vitamin C is an effective antioxidant and reactive oxygen species scavenger. In patients who can develop fluid overload, a high dose of Vitamin C can be a useful adjunct.
Therapeutic plasma exchange (TPE) or plasmapheresis is an uncommon treatment for refractory burn shock. TPE is empirically used as a rescue maneuver at some centers on a clinical trial basis only.
| Fluid in High-Voltage Electric Injuries|| |
Fluid resuscitation of patients with high-voltage electric injuries (HVEI) is more difficult than thermal burns. HVEI causes deep injuries. These deep para osseous injuries are not calculated in standard fluid resuscitation formulas. Only cutaneous burns are included in standard formulas. Myonecrosis because of HVEI can result in rhabdomyolysis, causing renal damage. Therefore, HVEI patients require more fluid volumes than patients with thermal burns. The use of cutaneous burn only in formulas can underestimate fluid requirement in HVEI patients.
The 1st-day fluid requirement in HVEI is calculated as RL 4 ml/Kg/% of TBSA burn. The fluid is administered at a rate to maintain a urine output of 1–1.5 ml/kg/h and pigment-free clear urine. Use of diuretics is not recommended because the urine output cannot be used as a measure to monitor adequate fluid resusucitation. The fluid rate is decreased when adequate urine output is maintained and urine is clear.
| Fluid in Obese|| |
Effects of obesity on fluid resuscitation after burn are not properly understood. The use of actual body weight in burns formula overestimates the fluid requirement.
NHS guidelines of Scotland recommend that fluid requirements should be calculated according to actual body weight and urine output ranges should use ideal body weight.
Rosenthal et al. suggested that the patient's ideal weight and computerized program adjusting the fluid with urine output may be better in obese patients.
| Conclusion|| |
Burn resuscitation is progressing, new trends develop, and old protocols are revisited. Future fluid resuscitation is likely to look like resuscitation of 1970 or 1980. Majority of burn occur in resource-poor countries and is not treated in a technologically enriched environment. However, we must remember Brown and Muller words in the 2003 editorial that burns' fluid management is not resource dependent. Future research should be directed to find an accurate indicator of adequate resuscitation in burns and the role of colloid solutions such as FFP and albumin in acute fluid management.
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