Drowning Flashcards
Definition
A process that results in primary respiratory impairment from submersion/immersion in a liquid.
Whether the victim lives or dies after this process is not important they have still drowned.
If they don’t survive then they have fatally drowned.
- Approximately 450,000 deaths each year with 205 deaths from accidental drowning in England and sales in 2009, many more near drownings to.
- Most involve young males or children
- Drowning is the alteration of oxygen delivery to tissues due to breathing in fluids.
- Major mechanism of injury is usually hypoxia.
- Airway obstruction is more important in the pathology of this with 15% of drowning victims having little or no water in the lungs due to vagal nerve-mediated laryngospasms - known as dry drowning.
- No matter the mechanism it will lead to cerebral hypoxia and unconsciousness.
- Irreversible injury develops more quickly in warm water.
-Complete submersion is not required for drowning, especially in incapacitated individuals.
- Primary cause may not be drowning
-Immersion is the covering in a liquid medium and the tissue here will be hypothermia nad cardiovascular collapse from the removal of the hydrostatic pressure of the surrounding water on the lower limbs.
- Submersion is the entire body on airway being under the liquid medium resulting in asphyxia and hypoxia.
- During submersion there will be an attempt to hold breath. This can cause laryngeal spasms with the water irritating the airway.
- Laryngeal spasms of 10-15%of victims is so intense that it does not allow any water into the lungs.
- When a drowning victim is unable to keep fluid from their mouth, it is spat out or swallowed.
- If still conscious, victims will then attempt to hold their breath, but this is likely to continue for less than a minute, depending on levels of panic and the temperature of the water.
- Once the inspiratory drive is too high to resist the victim will take a breath and water will be aspirated into their airway.
- Laryngospasms may occur but this is rapidly terminated by cerebral hypoxia and active ventilation with the aspiration of water will resume.
- Immersion in cold water (10 degrees or less) produces large and rapid reductions in skin temperature which in turn leads to COLD SHOCK.
- This term refers to a collection of physiological response including:
- An inspiratory gasp which can result in drowning if the victims airway is submerged.
- Hyperventilation
- hypocapnia
-Tachycardia
- Peripheral Vasoconstriction and hypertension
Cold shock is thought to be caused by stimulation of cutaneous cold thermoreceptors which can result in an excessive sympathetic nervous system.
- If the victim is fully submerged in cold water the diving response may be activated. This is caused by the cooling of cold thermoreceptors on the face which are innervated by the trigeminal nerve:
This can result in: - profound sinus bradycardia due to parasympathetic nervous system stimulation of the heart.
- Expiratory apnoea due to inhibition of central respiratory neurons.
- sympathetic nervous system - mediated vasoconstriction of the trunk and limbs.
- A sudden drop in venous return can reduce coronary perfusion enough to induce cardiac arrest. For this reason, it is advised to remove victims horizontally from the water if possible hypothermia is likely to occur so wet clothes should be cut off but minimizes movement,
Hypothermic patients are at risk of cardiac arrhythmias including ventricular fibrillation even with minor movement.
- Get the patient covered with blankets and in warm ambulances as soon as possible.
-Victims of prolonged immersion in water (typically 30 minutes or more but less as water temperature decreases) may also suffer the added complication of circum-rescue collapse. This is due to the increased hydrostatic pressure from the water on the victims legs and torso increasing the venous return and cardiac output.
- Central baroreceptors mistake this for hypervolaemia resulting in increased divresis.
- Get the victim out of the water as soon as possible and place them supine (on there back) with head and torso at the same level and check for breathing.
- if they are breathing but unconscious provide high-flow oxygen non-rebreather mask as per clinical guidelines and place them in the recovery position.
- They are at high risk of gastric regurgitation, so ensure that you have suction available.
- in cases of moderate and severe hypothermia, signs of life can be difficult to identify. You should therefore check for breathing and a pulse for up to 1 minute. If the patient has a core body temperature of less than 30 degrees, some modification of the advanced life support algorithm is required.
- In this case, a maximum of three shocks only should be administered if the patient is in VF or pulseless VT and no intravenous drugs should be given (Adrenaline or amiodarone) until the patient has been warmed up.
- Once the core body temperature is over 30 degrees but less than 35 degrees defibrillation can continue as usual but when administering IV drugs the time interval between each administration should be doubled (I.E. every 6-10 minutes). once the patient’s core body temperature is over 35 degrees they can be resuscitated as normal.
Secondary drowning
- Following drowning the presence of additional fluid in the lungs and the loss of surfactant lead to increasing areas of the lungs becoming regions of low or no ventilation and perfusion (pulmonary shunting), there will also be widespread atelectasis and bronchospasm.
- The fragile alveolar-capillary membranes are disrupted, leading to increased permeability and movement of fluid plasma and electrolytes.
- Clinically this leads to significant amounts of blood-stained pulmonary edema and decreasing gaseous exchange of oxygen and carbon dioxide.
Extremes of temperature
Thermoregulation
How does the body create heat?
- Basal metabolic activity
- Muscle movement
How can the body lose heat?
- Conduction
- Convection
- Radiation
- Evapouration
Core body temperature is between?
-35.5 - 37.5 degrees celsius
what part of the brain senses and responds to temperature control?
- Hypothalamus
Heart-Related illnesses
Hyperthermia
Hyperthermia is elevated body temperature due to failed thermoregulation it occurs when the body produces or absorbs more heat than it dissipates.
Despite being a rare occurrence heart-related illness can be of fatal consequences.
Heart-related illness can be caused via two sources:
- Exogenous which is caused by environmental factors (HEAT).
- Endogenous which is caused by other factors (drugs or exercise).
Heat stress and to a certain extent heat exhaustion would rarely present as a medical emergency.
