Part I – The Facts of the Case
I read the headlines, almost unbelieving. From all that disaster in Port-au-Prince, Haiti, in January 2010, a miracle occurred; someone was still alive, more than 2 weeks after the buildings collapsed around her. The paper reported that Darlene Etienne, a 17-year-old university student, was found in the rubble of a home near the university, very dehydrated, groaning weakly, but still conscious, with a very weak pulse and low blood pressure. Rescuers gave her oxygen and water and immediately evacuated her to a French military hospital ship for treatment.
“She was definitely within hours or perhaps minutes of death,” said one rescuer. “It’s exceptional that she managed to survive this long,” said another. “In fact, it is rare for anyone to survive more than 72 hours without water, and no survivors have been documented in any earthquake after 14 days.”
How did Darlene manage to survive? Was it due to her ability to conserve her body water, or did she somehow gain access to a meager supply of water while still buried?
Find websites with factual information about dehydration: Signs and Symptoms of Dehydration
- Title:___ Dehydration – Symptoms and causes _____ URL: http://www.mayoclinic.org/diseases-conditions/dehydration/symptoms-causes/dxc-20261072
- Title:____ Dehydration in adults ________ URL: http://www.webmd.com/a-to-z-guides/dehydration-adults#1
- Title:___ Dehydration __________ URL: _ http://www.medicinenet.com/dehydration/article.htm
Questions
- How many litres of water do you think you drink daily?
3.5 litres
- What do you think would happen to you first should you stop taking in water?
Pain in the throat
- How many litres of water do you think you express daily?
1 litre
- What are the physical signs and symptoms of progressive dehydration?
Dry mouth, nausea and vomiting, weakness, may stop sweating, muscle cramps
- What might Darlene have experienced since she was unable to move around?
Muscle cramps, dry mouth, may stop sweating, weakness
- What do we know so far about Darlene’s physiological responses to her prolonged ordeal?
Part II – Calculating Darlene’s Water Balance
The physiological consequences of Darlene’s entrapment in the earthquake rubble were dehydration, starvation, and potentially heat exposure from daytime temperatures near 35°C (95°F) and high humidity. However, let’s look first at just her ability to survive the dehydration of being buried for 15 days.
First, we should consider where water is “stored” in the body that could be tapped during Darlene’s prolonged entrapment.
Questions
- How is the hypothalamus involved in this case?
The hypothalamus governs the physiological functions like temperature, thirst, hunger, sleep, sex drive, mood etc. And releases the hormones into the body. This is related because it governs your thirst.
- Darlene was exposed to 35°C. What is the highest temperate you can recall you have been in?
40 degrees Celsius in California.
- Based on the diagram above, list the major water compartments of the body.
Cells, bones, tissue matter, fluids
- What is the 60-40-20 rule for body water?
60% of body weight is water, 40% is in the intracellular fluid, 20% is the extracellular fluid
- Assuming that Darlene did NOT have access to water during her entrapment, how would her body begin to lose water? She would probably sweat out most of the water due to the heat.
- What are the specific avenues of water loss?
Evaporation, urine, feces
- What is the function of vasopressin?
To retain water in the body and constrict blood vessels
- How much water is produced when fat is metabolized?
Around 100 grams of water per 100 grams of fat
- How might the body immediately begin to reduce those avenues of water loss in Question #4?
Metabolizing fat
- What important physiological reflexes would minimize the rate of water loss from those specific avenues?
Vasopressin would constrict blood vessels
- How would changes in blood flow to specific organs help Darlene resist dehydration? Consider how reduction of function in particular organ systems might help conserve water.
If certain systems that are unnecessary at the moment do less work than she will use less energy and focus on conserving more water
- Calculation of Darlene’s water loss—Enter answers in the spaces and table below as directed. 33kg/litre c. Data from published studies on women show that water loss varies as a function of age, weight, and environment. Values range from 2.7 L/day for young female adults (Sawha et al., 2005) to 3.3 L/day in active (but not exercising), young female students (Westerterp et al., 2010). How many days without water could Darlene survive at this rate of dehydration, assuming a maximum of 12% body water loss? Record your answer in the table below. f. At the absolute minimal rate of water loss (7e) and maximal tolerance of dehydration (20% of total body water from 7b), how many days without water could Darlene survive? Record your answer in the table below. 7b. 12% of total body water in litres _____________6.6litres__________________________
- 7b. 20% of total body water in litres ____________11litres___________________________
- 7a. Total body water in litres (55 kg human) _______33litres__________________________
- g. Now, based on these calculations, could Darlene have survived 15 days without water? Explain the basis for your answer.
- e. The absolute bare minimum water loss possible for humans, with all compensating mechanisms in force, is about 1.2–1.4 L/day (approximately 6 cups of liquid). How many days could Darlene survive at this rate of water loss? Record your answer in the table below.
- d. Are these water loss values (in 7c) of any use in predicting how much water Darlene might have lost per day? Justify your answer.
- 11litres
- b. Most humans can withstand only a 12% loss of total body water before they progress to clinical shock. The lethal body water loss for humans is 20% of total body water. Based on these estimates, how many litres of body water can Darlene afford to lose? Record your answer below.
- a. Let’s assume that Darlene weighs about 55 kg (~120 lb). Based on the 60-40-20 rule, how much total body water (in litres) does Darlene have? Record your answer below.
| Condition | Rate of water loss | Survival time in days |
| 7c. Average water loss for young adult females, 12% total body water loss
|
2.7 L/day | 3 days |
| 7c. Average water loss during summer for European women (55 kg), 12% total body water loss
|
3.3 L/day | 2 days |
| 7e. Absolute minimal water loss possible in humans, 12% total body water loss
|
1.2-1.4 L/day | 5 days |
| 7f. Absolute minimal water loss possible in humans, 20% total body water loss
|
1.2-1.4 L/day | 8.5 days |
Part III – Finding other Explanations for Darlene’s Survival
Darlene’s survival was indeed miraculous, but was it based in part on who she was, where she lived (Haiti), and the particular conditions to which she was exposed? Survival can sometimes depend on the smallest of advantages.
Questions
- Would a middle-aged, northern European (or Canadian) male tourist in Haiti have fared as well as Darlene? No he would not because males have less fat compared to females and his body wouldn’t be used to the temperature in Haiti.
- Are there physiological advantages of being a young female, born and raised in Haiti? Describe how these characteristics might have given her an advantage. In answering this question, consider the following: Darlene’s survival? Explain how. Yes because her being there her whole life she is used to the harsh conditions and temperature of Haiti, so her body is already prepared for this type of situations. Yes. The younger you are the better your body functions and is better prepared to survive. If you were fat than you would have more fat to metabolize. If you were male you would have less fat on you and therefore survive for less time than a female. d. Would Darlene’s sweat have more or less salt than you? Less because your blood vessels would be constricted to conserve water using
- f. Being a female, how does menstruation effect plasma volume?
- e. Would your blood to the surface of your skin be less or more?
- More salt because there would be less water in her sweat
- Because she was born in Haiti, her body is used the conditions and temperature of Haiti and her body is used to storing water quite often due to less water and more heat
- c. Does the fact that Darlene was born and raised in Haiti matter? Describe the role that heat acclimation might play in her water balance.
- b. Does age, weight, or sex affect water loss or water requirements (see Sawha et al., 2005)?
- a. Could being buried in rubble in the warm, humid environment of Haiti have been an advantage for
- Darlene survived a prolonged period of starvation, an additional physiological challenge for her body. Paradoxically, starvation might actually offset and/or minimize some water loss. How?
Part IV – An Answer?
Some residents thought that Darlene had been trapped in a bathroom, where she was showering at the time of the earthquake. Darlene told rescuers she had a little Coca-Cola with her when the earthquake struck – but was there enough precious liquid for her to survive 15 days? From the newspaper article at the beginning of the case, we know that Darlene probably did not exhibit the maximal dehydration that would have resulted in her losing consciousness (i.e., >12% body water loss).
Questions
- Based on your calculations above, how much water would Darlene have needed to consume daily to reduce the rate of her dehydration such that she lost a maximum of only 10% of her body water after 15 days?
- If you were Darlene, what would you have preferred instead of Coca Cola? Why?
A bottle of water because there is no better liquid than water
- How might this story be different if it was in Vancouver in the summer?
it depends on who it happened to. If Darlene was in Vancouver at the time I think it would have been easier for her to survive. If it was a Vancouverite than I don’t think they would survive because they are not used o shortage of water and the heat all the time