Case Study: The Hot Tub Mystery

This case study describes how Clint & Roma Underhill were discovered dead in their hot tub. The day of their death was described as unusually cool (though it was only ~15ºC… must be nice to live in Desert Palm... ). Empty wine bottles were surrounding the couple, and when the ambulance personnel arrived they observed that the hot tub was very hot - 115ºF. Mr. Underhill had also been taking a drug known as Lasix.

The following are the facts submitted by the medical examiner:

  • BAL (blood alcohol level) of the couple was 0.20
  • Roma weighed 120 lbs; Clint weighed 160 lbs
  • There was a therapeutic amount of Lasix present in Mr. Underhill’s blood, but none in Mrs. Underhill’s.
  • The couples’ hot tub was unusually hot (should not be over 109ºC)

Determining the cause of death:

There are many pieces to this puzzle and when attempting to determine the cause of death for the couple, you must consider the following physiological affects:

Lasix:

  • Diuretic used to treat congestive heart failure, edema (swelling of tissues) and hypertension (high blood pressure)
  • Increases circulation of blood through kidneys lowers blood pressure

Blood alcohol level (BAL):

  • Concentration of alcohol in a person’s blood (mass per unit volume)
  • BAL ≥ 0.2% represents serious intoxication (over 0.08% is too drunk to drive!)

Alcohol effects:

  • Include diuretic (increasing kidney output lower blood pressure) leading to dehydration, and impaired judgment

Metabolism of alcohol:

  • Ethanol →acetaldehyde→pyruvate
  • 88 % metabolized, beginning immediately after ingestion
  • 10% excreted in urine within 40 minutes
  • ~2% evaporated (i.e. in breath)

Heat stroke (hyperthermia):

  • The result of the body’s inability to regulate internal temperature as a response to high environmental temperatures (failure of homeostasis)
  • Usually precipitated by low blood pressure

Cause of Death:

The deaths of Mr. & Mrs. Underhill are likely due to a combination of multiple factors. Firstly, the extreme heat of the hot tub will put pressure on the couples’ homeostatic heat mechanisms. Normally, thermoregulation mechanisms would kick in and lower the body temperature (through opening up sweat glands and increased heat exchange with the air). However, several factors prevent this:

  • Heat exchange is more difficult with water than in air
  • The couple had consumed so much alcohol that they were unable to metabolize it quickly enough, resulting in a high BAL
  • The BAL of the couple indicates that their judgement was likely impaired (perhaps a reason they stayed in the tub so long)
  • The high BAL will also lower the blood pressures of the couple.
  • An external environment with a high temperature, coupled with the low blood pressures of the couple indicate that heat stroke was a likely cause of death for Mr. & Mrs. Underhill
  • Though Mr. Underhill weighs more, and thus his BAL would have less of an effect, the fact that he was taking Lasix, which also lowers blood pressure, likely contributed to his death.