Hy 2213 Thanks for responding to heatstroke, it is SO high yield…
It is so common, esp. if you “match” along the southern U.S. or in urban setting where proper air conditioning may not be found. If you are presented in the ER with a patient (peds, elderly, or median age), do you know just how to treat him/her? I heard this is a popular favorite question because it demonstrates such a common chief complaint…esp. as we approach warmer weather!!! Again, how do you treat a heatstroke patient? Think of the original workup, tests, and as I mentioned, what types of fluids? (Again, choose NS as the answer for the fluid part)
a) Think first of how the patient will present:
Orthostatic pulse and blood pressure changes
Assume that any patient presenting with an elevated temperature, signs of CNS dysfunction, and a history of heat exposure has heatstroke and treat immediately.
CNS dysfunction includes seizure, coma, delirium, bizarre behavior, opisthotonus, hallucinations, decerebrate rigidity, cerebellar dysfunction, oculogyric crisis, and fixed and dilated pupils.
Coagulation disorders include disseminated intravascular coagulation (DIC) and result in signs such as purpura, conjunctival hemorrhage, melena, bloody diarrhea, hemoptysis, hematuria, myocardial bleeding, and CNS hemorrhage.
Skin findings may range from warm and dry to diaphoretic. Many individuals with temperatures higher than 41°C are sweating diffusely. Anhydrosis typically is a late finding in heatstroke and is more common in classic than in exertional heatstroke.
Respiratory symptoms include tachypnea, alkalosis, and respiratory decompensation secondary to acute respiratory distress syndrome (ARDS).
Genitourinary symptoms include hematuria, oliguria, or anuria that may occur as signs of acute renal failure.
Unlike malignant hyperthermia and neuroleptic malignant syndrome, heatstroke is not characterized by muscular rigidity. Muscle cramps or flaccidity may be noted.
As we discussed above, the primary cause is failure of thermoregulation due to heat stress. But always KEEP IN MIND the “weird” stuff, like MALIGNANT HYPERTENSION and THYROID STORM. Boards can DEFINITELY fool you if you do not know these COLD.
If they ask you what LABS you would order, what will you say? Think again ORGANIZED and SYSTEM based:
As Dr Goljan said to me, the liver “does everything”. So get hepatic transaminases: These are elevated almost universally in heatstroke. Reconsider the diagnosis of heatstroke if aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels are within the reference ranges.
CBC, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and platelets: These tests may provide evidence of coagulation disorders and hemoconcentration.
Electrolytes, BUN, and creatinine: Evaluate for acute renal failure, acid-base disorders, uremia, and hyperkalemia.
Blood glucose: Hypoglycemia may occur because of increased use of glucose or hepatic damage leading to impaired gluconeogenesis.
Creatine kinase (CK): The CK level is elevated in rhabdomyolysis, especially in exertional heatstroke.
Arterial blood gases (ABGs): These measurements are useful to evaluate acid-base status, pulmonary function, and tissue oxygenation. Nonexertional cases typically have respiratory alkalosis, while exertional cases may have both respiratory alkalosis and lactic acidosis.
Do NOT forget a Urinalysis
Proteinuria, hematuria, myoglobinuria, or granular casts provide evidence of acute renal failure or rhabdomyolysis.
Urine specific gravity typically is increased. Did you know as Dr. Goljan said to me how important a urine analysis is????
Do NOT forget to get a chest radiography
Perform chest radiography (CXR) to evaluate for ARDS, aspiration, and pneumonia.
CXR may be useful in excluding differential diagnoses (eg, thermal myocardial dysfunction, which may result in a pulmonary edema pattern on CXR film despite dehydration).
Also, the brain is definitely affected… so get or “pick” a CT scan of the head
Evaluate for CNS edema and hemorrhage.
This test is important to exclude differential diagnoses in patients with altered level of consciousness.
Do not forget also a rectal thermometer probe for constant core temperature monitoring.
As far as meds go, they may ask you what meds NOT to give. Think about it. First thing is “eliminate” the anti-cholinergics! Do you really want to STOP sweating in a patient with hyperthermia??? Use your common sense too.. Avoid several drugs, including those anticholinergics (decrease sweating), alpha-adrenergic agonists (increase peripheral resistance without increasing cardiac output), and antipyretics.
There are a lot of management questions like giving them an “ice bath” and stuff, but that is more Step 2 than Step 1. But listen carefully, Board is heavy on Most Commons, D5 (Dextrose in water), as Dr. Goljan said to me, is basically giving them only water…95% is pure H20. Since tonicity is the problem too, the best choice is Normal Saline. OK? It is so readily available, you do not have to do calculations, and it WILL work, and you will see in clinics when YOU ALL become a doctor, that NS is used. I know others “could” be used, but normal saline is in every single hospital room and you will see it hanging on just about everyone’s bed. Yeah, yeah, I know Lactate Ringer’s could work, but usually pick that when you are given a case of like someone in an abdominal surgical trauma, where pH is more important. Again, NS is the best answer. Trust me on this…
Now, what the boards MAY FOOL you on is, HOW MUCH normal saline is needed. It is a Step 1 question, not only for Step 2. In fact, I will admit that I PERSONALLY on my own test got a “How much Normal Saline in liters?” needed to be given to a patient, and I had to consider the Total Body Water, Intracellular place, Extracellular space, etc. KNOW fluids COLD. Recall, we are mostly “fluids.”… eh? J Love, Tommy