A 37-year-old male has been admitted to your ICU following an explosion in his garage. He has suffered a mixture of partial and deep burns estimated at 35% total body surface area, and he has been intubated in the Emergency Department. After one hour of resuscitation in your unit he remains hypotensive with a blood pressure of 80/50 mmHg.
List the potential causes and outline how you would diagnose and manage them.
College answer
- Spurious
- Damped or poorly functioning, zeroed, arterial line
- Inappropriate sized cuff
- Check line, cuff size
- Measure second site, alternative modality
- Hypovolemia
- Review volumes of administered fluids to date
- Confirm size and depth of burn
- Check calculations for fluid resuscitation are correct
- Rising haematocrit, ECHO findings
- Increase fluid resuscitation rate
- Bleeding from occult/missed injury
- Review/repeat trauma imaging
- Blood product resuscitation, correction of coagulopathy
- Operative/Interventional radiology interventions to treat cause
- Review/repeat trauma imaging
- Sepsis
- Too early for burn sepsis – possible intraabdominal or thoracic blast injury
- Broad spectrum antibiotics and source control
- Too early for burn sepsis – possible intraabdominal or thoracic blast injury
- Distributive
- High cervical spine injury
- Review imaging, vasopressors
- Anaphylaxis to drugs
- Review history, examine for rash/bronchospasm, adrenaline
- Cyanide toxicity
- Mixed venous oxygen, empirical antidote administration
- High cervical spine injury
- Cardiogenic
- Takustubo, underlying cardiac disease, blast injury, myocardial toxins
- ECHO, ECG, Inotropic support
- Takustubo, underlying cardiac disease, blast injury, myocardial toxins
- Obstructive
- Tension pneumothorax
- CXR, drainage
- Abdominal compartment syndrome
- Bladder pressure, escharotomies, laparotomy/laparostomy
- Tamponade
- Echo and pericardiocentesis
- Tension pneumothorax
Examiners Comments:
Frequently poorly structured answer, with a list of causes of hypotension, then repeated with diagnosis and management. Worked better when candidates classified each category of shock, then described individual diagnosis and management within each category. Often the question had not been carefully read, and the time already spent in ED and ICU was ignored; then a simplistic EMST initial approach to trauma was given.
Discussion
This question resembles Question 26 from the second paper of 2016, except the patient is not unconscious and there is no ABG to interpret.
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
If one were to offer more detail, one would have to tabulate one's answer, which would handily answer complaints about a lack of structure, because nothing says "structure" like a table.
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 |
|
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