A 54-year-old previously healthy male was admitted to the ICU after 45% total body surface area burns. He was pulled out of his garden shed, unconscious, by the fire brigade and was intubated at the scene of the incident by ambulance personnel. He was admitted to the ICU within one hour of injury.
a) Describe your initial fluid resuscitation plan for this patient, including the type of fluid, the rationale for your choice and how you would estimate the fluid requirements.
Three hours later, the patient remains hemodynamically unstable:
Heart rate 125 beats per minute
Blood pressure 85/45 mmHg (on noradrenaline 30 μg/min and vasopressin 0.04 units/min)
b) What are the diagnostic possibilities?
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. Patient response to fluid therapy needs careful monitoring and
adjustment as clinically indicated
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 multiple co-morbidities.
b)
Unidentified blood loss / inadequate fluid resuscitation
Distributive shock with large fluid shifts
Cyanide toxicity
Compartment Syndrome, including abdominal compartment
Cardiogenic Shock (severe myocardial suppression caused by burns)
Carbon monoxide poisoning
Ingestion of toxins (ethylene glycol, methanol, salicylates)
Additional Examiners’ Comments:
Candidates omitted discussion on rationale for choice of fluid
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.
In brief:
Fluid resuscitation end point:
Choice of fluids:
Resuscitation formulae
Formula | First 24 hours | Next 24 hours | ||
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 |
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:
Let this be an exercise in generating differentials.
In more detail:
Type of shock | Cause | Diagnostic strategy | Management |
Artifact of measurement | Arterial blood pressure measurement is inaccurate | Compare with non-invasive measurement and physical examination |
|
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 |
|
Myocardial infarction | TTE, ECG, cardiac enzymes |
|
|
Obstructive | Abdominal compartment syndrome | Measure the intra-abdominal pressure; calculate total fluid resuscitation (it is associated with over-resuscitation) |
|
Massive pulmonary embolism (unlikely - too early - more likely in the chronic recovery from burns) |
TTE, CVP trace, ECG, CTPA |
|
|
Tension pneumothorax (likely, if there the patient was in some sort of explosion) |
Physical examination; CXR |
|
|
Neurogenic | Spinal injury due to fall; may have gone unrecognised given that the patient was found unconscious | Physical examination features, CT, MRI |
|
Hypovolemic | Blood loss | Examination of the patient, FBC, DIC screen |
|
Under-resuscitated burns shock | Compare fluid resuscitation with predicted expectations as based on the formulae |
|
|
Distributive | Vasoplegia due to SIRS | SVRI measurements by PiCCO |
|
Anaphylaxis | Physical examination findings suggestive of angioedema |
|
|
Cytotoxic | Cyanide toxicity due to smoke inhalation | Lactate levels; cyanide levels |
|
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