Question 26

A 54-year-old previously healthy male was admitted to the ICU within one hour after sustaining burns to 45% total body surface area. He had been pulled out of his garden shed, unconscious, by the fire brigade and intubated at the scene of the incident by the paramedics.

a) Describe your initial fluid resuscitation plan for this patient including type of fluid, rationale for your choice and estimation of the fluid requirements. (60% marks)

Three hours after presentation, despite adequate fluid resuscitation, the patient remains haemodynamically unstable.

Heart rate 125 beats/min

Blood pressure 85/45 mmHg (on noradrenaline 30 mcg/min and vasopressin 0.04 units/min)

Arterial blood gas result is as follows:

Parameter	Patient Value	Normal Adult Range
Fi02	0.5
pH	7.21*	7.35 - 7.45
PC02	22 mmHq (2.9 kPa)*	35 - 45 (4.6 - 6.0)
P02	90 mmHq (11.8 kPa)
Bicarbonate	8 mmol/L*	22 - 28
Base excess	-15 mmol/L*	-2 - +2

b) List the possible causes for this clinical picture. (40% marks)

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College answer

a) Type of fluid:
Fluid resuscitation of patient with moderate to severe burns consists of an isotonic crystalloid solution, such as Hartmann‟s solution or plasmalyte. Large volumes of 0.9% NaCl may be associated with hyperchloremic metabolic acidosis.
The colloids (albumin) are more expensive, and do not improve survival, compared to crystalloids.
The use of hypertonic saline does not provide better outcomes than isotonic saline.

Estimating fluid requirements:
No formula provides a precise method for determining the burn victim's fluid requirements; the formulas described provide only a starting point and guide to initial fluid resuscitation. Patient age, severity of burns and co-morbidities can substantially alter the actual fluid requirements of individual patients.
Parkland (or Baxter or consensus) Formula (most widely used):
Fluid requirement (ml) = 4 x body weight x percentage of burns. (Only deep)
One half of the calculated fluid is given over the first eight hours and the remaining over the next 16 hours.
The rate of infusion should be as constant as possible; sharp decrease in infusion rates can cause vascular collapse and increase in edema.
Modified Brooke Formula: Fluid requirement (ml) over the initial 24 hours = 2 x body weight x percentage of burns.
This formula may reduce the total volume used in fluid resuscitation without causing harm.
Following initial resuscitation, IV fluids are administered to meet baseline fluid needs and maintain urine output.
Care should be taken to avoid fluid overload, as associated with pulmonary edema, peripheral edema leading to compartment syndrome.
Inadequate resuscitation suggested by poor urine output should be managed by judicious fluid boluses and an increase in the infusion rate.

b) List the diagnostic possibilities
Cardiogenic Shock (severe myocardial suppression caused by burns, pre-existing myocardial dysfunction)
Cyanide toxicity
Compartment Syndrome, including abdominal compartment
Carbon monoxide poisoning
Blast injury
Ingestion of toxins (ethylene glycol, methanol, salicylates)
Acute Liver Failure

Additional Examiners' Comments:
Most of the candidates answered this question very well. Candidates who did not pass showed knowledge gaps, poor synthesis of knowledge and poorly structured answers.

Discussion

This question closely resembles Question 21 from the first paper of 2014, with the exception of the fact that this time an ABG was also offered.The ABG does not add very much to the process of answering this question, and therefore the discussion section for Question 21 is reproduced here with minimal modification.A detailed dissection of fluid resuscitation for the burns patient is performed in the Required Reading section. Physiologic consequences of burns is also covered there. The ABG looks like a metabolic acidosis, which would accompany any sort of shock state - and so the "Causes of Shock in the Acute Burns Patient" table was still relevant here.

In brief:

Fluid resuscitation end point:

urine output of 0.5-1.0 ml/kg/hr (Paratz et al, 2014)
MAP >65mmoHg

Choice of fluids:

Resuscitation should use a balanced solution to avoid hyperchloraemic acidosis (Walker et al, 2001)
Most formulae recommend Ringer's Lactate; the locally available version is Hartmanns
The disadvantage of crystalloid is the potential need for massive volume
Historically, significantly more fluid is given to burns patients then is predicted by any formula (Mitra et al, 2006). This is known as "fluid creep" and is associated with significant complications, of which the most serious is abdominal compartment syndrome.
Colloid (eg. albumin) is also recommended by many of the formulae
The advantage of colloid is that it may alleviate "fluid creep" and achieve haemodynamic goals more rapidly and with less volume
There is no evidence that albumin improves survival or organ dysfunction (Melinyshyn et al, 2013)
The theoretical advantage of hypertonic saline is earlier achievement of haemodynamic goals and the avoidance of burns-associated hypernatremia. However, hypertonic saline solutions were associated with a fourfold increase in the risk of renal failure and a twofold increase in the risk of death (Huang et al, 1995)

Resuscitation formulae

Formulae to Estimate Fluid Resuscitation Requirements in Adult Burns
Formula	First 24 hours		Next 24 hours
Formula	Choice of fluid	Volume	Choice of fluid	Volume
Parkland	Ringer's Lactate	4ml/kg/% first half in 8 hrs second half in 16 hr	Colloids only. No more crystalloids.	20–60% of calculated plasma volume.
Modified Parkland	Ringer's Lactate	4ml/kg/% first half in 8 hrs second half in 16 hr	5% albumin	0.3–1 ml/kg/% burn/16 per hour
Brooke	Ringer's Lactate	1.5 ml/kg/%	Ringer's Lactate	1.5 ml/kg/%
	Colloids	0.5 ml/kg/%	Colloids	0.25 ml/kg/%
	Dextrose 5%	2000ml	Dextrose 5%	2000ml
Modified Brooke	Ringer's Lactate	2 ml/kg/%	Colloids	0.3–0.5 ml/kg/%
Evans	Crystalloid	1 ml/kg/%	Crystalloid	0.5 ml/kg/% burn
	Colloid	1 ml/kg/%	Colloid	0.5 ml/kg/% burn
	Dextrose 5%	2000ml
Monafo	250 mEq Na 150 mEq lactate 100 mEq Cl.	titrate to u/o	250 mEq Na 150 mEq lactate 100 mEq Cl.	titrate to u/o
Monafo	250 mEq Na 150 mEq lactate 100 mEq Cl.	titrate to u/o	1/3 saline	titrate to u/o

It is probably worth adding that this patient is at high risk of inhalational injury. He was unconscious, and sharing a small enclosed space with his fire. Naver et al (1985) demonstrated that patients with smoke inhalation injury and airway burns require a larger volume of fluid resuscitation. The total volume is increased up to 35% - 65%.

Causes of shock in the unconscious burns patient with metabolic acidosis

Let this be an exercise in generating differentials.

Wrong BP measurement (eg. arterial line is not zeroed)
Cardiogenic shock
- Due to cytokine storm of severe burns
- Due to carbon monoxide toxicity (i.e. severe tissue hypoxia)
- Due to cyanide toxicity (i.e. mitochondrial failure)
- Due to a myocardial infarction (due to increased myocardial oxygen consumption in context of burns, on top of pre-existing ischaemic heart disease)
Abdominal compartment syndrome (over-resuscitation)
Tension pneumothorax (explosion)
Spinal injury neurogenic shock (unrecognised due to unconsciousness)
Blood loss from some internal injury or due to DIC
Under-resuscitated burns shock (i.e. fluid shifts)
SIRS vasoplegia
Anaphylaxis to some drug given in hospital

In more detail:

Causes of Shock in the Acute Burns Patient
Type of shock	Cause	Diagnostic strategy	Management
Artifact of measurement	Arterial blood pressure measurement is inaccurate	Compare with non-invasive measurement and physical examination	Re-zero and recalibrate the arterial line Resite arterial line or change the transducer
Cardiogenic	Cytokine-induced myocardial dysfunction Alternatively, cardiac dysfunction can be associated with cyanide and carbon monoxide toxicity	TTE, ECG, cardiac output measurement by PiCCO or PA catheter	Fluid resuscitation Commence inotrope infusion Correct rhythm if in AF
	Myocardial infarction	TTE, ECG, cardiac enzymes	Consider IABP Thrombolysis or anticoagulation likely contraindicated given the potential need for escharotomy or debridement
Obstructive	Abdominal compartment syndrome	Measure the intra-abdominal pressure; calculate total fluid resuscitation (it is associated with over-resuscitation)	Maintain MAP with vasopressors Consider opening the abdomen Consider diuresis (although, at this stage the urine output is limited by poor renal perfusion)
	Massive pulmonary embolism (unlikely - too early - more likely in the chronic recovery from burns)	TTE, CVP trace, ECG, CTPA	Consider emergency embolectomy Thrombolysis or anticoagulation likely contraindicated given the potential need for escharotomy or debridement
	Tension pneumothorax (likely, if there the patient was in some sort of explosion)	Physical examination; CXR	Emergency decompression Chest drain
Neurogenic	Spinal injury due to fall; may have gone unrecognised given that the patient was found unconscious	Physical examination features, CT, MRI	Commence vasopressor infusion
Hypovolemic	Blood loss	Examination of the patient, FBC, DIC screen	Replace blood products and red cells Fluid resusiciation Maintain normal acid-base balance and normothermia Correct coagulopathy
	Under-resuscitated burns shock	Compare fluid resuscitation with predicted expectations as based on the formulae	Replace appropriate volume Aim for urine output 0.5-1.0ml/kg Consider albumin, and to hell with the evidence
Distributive	Vasoplegia due to SIRS	SVRI measurements by PiCCO	commence vasopressor infusion; consider methylene blue
	Anaphylaxis	Physical examination findings suggestive of angioedema	Adrenaline IM or as infusion Withdrawal of the trigger substance Corticosteroids and antihistamines
Cytotoxic	Cyanide toxicity due to smoke inhalation	Lactate levels; cyanide levels	hydroxycobalamin dicobalt edetate sodium thiosulfate methaemoglobinaemia

References

Mitra, Biswadev, et al. "Fluid resuscitation in major burns." ANZ journal of Surgery 76.1‐2 (2006): 35-38.

Haberal, Mehmet, A. Ebru Sakallioglu Abali, and Hamdi Karakayali. "Fluid management in major burn injuries." Indian journal of plastic surgery: official publication of the Association of Plastic Surgeons of India 43.Suppl (2010): S29.

Fodor, Lucian, et al. "Controversies in fluid resuscitation for burn management: Literature review and our experience." Injury 37.5 (2006): 374-379.

Bak, Zoltan, et al. "Hemodynamic changes during resuscitation after burns using the Parkland formula." Journal of Trauma and Acute Care Surgery 66.2 (2009): 329-336.

Blumetti, Jennifer, et al. "The Parkland formula under fire: is the criticism justified?." Journal of burn care & research 29.1 (2008): 180-186.

Baxter, Charles R., and Tom Shires. "Physiological response to crystalloid resuscitation of severe burns." Annals of the New York Academy of Sciences 150.3 (1968): 874-894.

Saffle, Jeffrey R. "The phenomenon of “fluid creep” in acute burn resuscitation." Journal of burn care & research 28.3 (2007): 382-395.

Naver, P. D., J. R. Saffle, and G. D. Warden. "Effect of inhalation injury on fluid resuscitation requirements after thermal injury." Plastic and Reconstructive Surgery 78.4 (1986): 550.

Arlati, S., et al. "Decreased fluid volume to reduce organ damage: a new approach to burn shock resuscitation? A preliminary study." Resuscitation 72.3 (2007): 371-378.

Bittner, Edward A., et al. "Acute and Perioperative Care of the Burn-Injured Patient." Survey of Anesthesiology 59.3 (2015): 117.

Melinyshyn, Alex, et al. "Albumin supplementation for hypoalbuminemia following burns: unnecessary and costly!." Journal of Burn Care & Research 34.1 (2013): 8-17.

Cooper, Andrew B., et al. "Five percent albumin for adult burn shock resuscitation: lack of effect on daily multiple organ dysfunction score." Transfusion 46.1 (2006): 80-89.

Wilkes, NICHOLAS J. "Hartmann's solution and Ringer's lactate: targeting the fourth space." Clinical Science 104.1 (2003): 25-26.

MONAFO, WILLIAM W. "The treatment of burn shock by the intravenous and oral administration of hypertonic lactated saline solution." Journal of Trauma and Acute Care Surgery 10.7 (1970): 575-586.

Huang, Peter P., et al. "Hypertonic sodium resuscitation is associated with renal failure and death." Annals of surgery 221.5 (1995): 543.

Sun, Ye-Xiang, et al. "Effect of 200 mEq/L Na+ hypertonic saline resuscitation on systemic inflammatory response and oxidative stress in severely burned rats." Journal of Surgical Research 185.2 (2013): 477-484.

Paratz, Jennifer D., et al. "Burn Resuscitation—Hourly Urine Output Versus Alternative Endpoints: A Systematic Review." Shock 42.4 (2014): 295-306.

Walker, Steven C., et al. "Balanced Electrolyte Solution Reduces Acidosis as Compared to Normal Saline in the Resuscitation of Perioperative Burn Patients." Anesthesiology 95 (2001): A375

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