Submersion and Environmental Injuries

Question 1

Define drowning

Answer 1

Drowning is defined by respiratory failure due to submersion (airway below the liquid) or immersion (airway above the liquid ie. face down in a bath) in a liquid.

Question 2

When is it estimated that hypercapnia overrides your ability to hold your breath?

Answer 2

55 mmhg (typically around 2 minutes)

Question 3

In up to 15% of drownings, the patient aspirates no water. Why?

Answer 3

Prior to LOC gasping and coughing can occur causing large amounts of water to be swallowed.
Once water enters the pharynx and/or trachea the pt will suffer from laryngospasm, and this can be permanent or temporary.
If the spasm is permanent there will be no aspiration.

Question 4

In drownings where laryngospasm is temporary, what happens?

Answer 4

When temporary, fluid begins to enter the lungs which further compounds hypercapnia and hypoxia causing cardiac arrest.

Question 5

How long after loss of consciousness does brain damage occur?

Answer 5

Between 4-6 minutes after LOC.

Question 6

What is the typical progression of heart rhythms during drowning deaths?

Answer 6

Tachy, brady, PEA, and asystole.

Question 7

What should we note about the water in drownings that is important to patient treatments and outcomes?

Answer 7

How polluted the water is, whether it was muddy or clear, or if there was sewage present in the water that was aspirated.

Question 8

There is no difference in survivability between saltwater and freshwater drownings, but what is one difference in presentation that could arise?

Answer 8

If large amounts are consumed in the non-fatal drowning fresh water has lower osmolarity, therefore an increase blood volumes causing the breakdown of red blood cells (hemolysis). This doesn’t occur with salt water because the osmolarity is relatively equal.

Question 9

What is the mammalian diving reflex?

Answer 9

Triggered by cool water. Causes bradycardia, peripheral vasoconstriction, and reduced 02 demand.
This protective reflex is more pronounced in pediatrics who also have greater o2 carrying capacity, and also cool much faster due to larger body surface area.

Question 10

When might we expect to see ARDS in a drowning pt?

Answer 10

In later stages due to surfactant washout.

Question 11

Drownings can cause complications for patients up to 8 hours after the original emergency. Why?

Answer 11

Smalls amounts of aspirated water can either be reabsorbed in vasculature or can cause decrease in lung compliance, loss of surfactant, atelectasis and hypoxia. This can be immediate or delayed 4-8 hours

Question 12

What is ARDS and why is it bad?

Answer 12

A cascade of processes impacting alveoli/capillaries causing increased capillary permeability, leading to non-cardiogenic pulmonary edema (from loss of protein) and decreased surfactant.
This transitions to atelectasis, decreased lung capacity, ventilation/perfusion mismatch (if only one lung is impacted it will not be ventilated but still perfused), and hypoxia.

Question 13

How long can pts typically survive in warm water?

Answer 13

<30 min

Question 14

How long can pts typically survive in cold water?

Answer 14

<60 minutes, but there are case studies of patients, normally kids submerged for longer than 60 minutes in cold water.

Remember, they’re not dead until they’re warm and dead.

Question 15

What is atmospheric pressure at sea level?

Answer 15

760 mmhg / 1 atmosphere absolute (ATA)

Question 16

When diving, how many feet down equals an increase of 1 ATA in pressure?

Answer 16

A decrease in depth causes an increase in pressure, which is 1 ATA per 33 foot descent.

Question 17

What is Boyle’s Law?

Answer 17

At a constant temperature, the volume of gas is inversely proportional to its pressure.

Example: Syringe - if you put your thumb over a syringe and push the plunger, it will get pushed back because volume decreases and pressure increases.

Question 18

What is a partial pressure?

Answer 18

The pressure exerted by an individual gas in a mixture.

Question 19

What is Dalton’s Law?

Answer 19

The total pressure of the mixture of gases is equal to the sum of of the partial pressures of each individual gases.

Question 20

What is Henry’s Law?

Answer 20

At a constant temperature, the amount of gas dissolved in a liquid is proportional to the partial pressure of gas above the liquid.

Think of pop. Before a bottle of pop is opened, the gas above the drink is almost completely co2 at pressure higher than atmospheric pressure. There is also dissolved co2 in the liquid, and once opened the pressure above the liquid is lower causing bubbles to occur and be released to the atmosphere.

Question 21

What is barotrauma?

Answer 21

Barotrauma occurs because of Boyle’s law. Gas filled spaces in the body can expand or contract. When on descent it is sometimes referred to as the “squeeze” and on ascent a “reverse squeeze”. Typically this presents no issues, as long as the diver is able to equilibrate (ie pop ears), but if there is a blockage in the ear for instance there could be problems.
Most conditions are self limiting and include, tympanic membrane rupture, tinnitus, vertigo, nausea, vomiting, etc.

Question 22

What does POPS stand for?

Answer 22

Pulmonary Overpressurization Syndrome

Question 23

What is POPS?

Answer 23

When a diver makes his ascent there can be air trapped within the lungs from breath holding, bronchospasm, or mucus plugs, which cause alveolar rupture.

Question 24

S&S of POPS?

Answer 24

Dyspnea, pleuritic pain, sub-q emphysema, or pneumothorax.

Question 25

What should we consider in loss of consciousness within 10 minutes of a diver resurfacing?

Answer 25

Air Embolism - gas expands, causing damage to tissue and forcing air into circulation. Can either be in arterial or pulmonary circulation, and most often are multiple bubbles of varying sizes that can impact cerebral, cardiac or pulmonary blood flow.