Trauma - Drowning

Question 1

Define drowning

Answer 1

Primary respiratory impairment following submersion or immersion in a liquid mediumCan be classified according to clinical findings at the scene:Class 1: No evidence of aspirationClass 2: Evidence of aspiration but with adequate ventilationClass 3: Evidence of aspiration with inadequate ventilationClass 4: Absent ventilation and circulation

Question 2

What are the pathophysiological changes that occur during drowning?

Answer 2

1. Respiratory:- panic, breath holding, laryngospasm- eventually hypoxia leads to relaxation of laryngeal muscles and acidosis with hypercapnia leads to stimulation of respiration.- Aspiration leads to: surfactant washout, bronchospasm, direct alveolar toxicity.- Pulmonary oedema and atelectasis leads to V/Q mismatch and ARDS.2. Cardiovascular:- Diving reflex (aims to conserve O2) stimulated by CNV1 results in bradycardia and vasoconstriction- Catecholamine surge leads to further vasoconstriction, arrhythmias and pulmonary oedema- progressive hypoxia leads to bradycardia and cardiac failure.3. Neurological:- hypoxic brain injury4. Metabolic:- hypothermia5. Infection:- from aspiration- usually gram +ve organisms- Gram -ve organisms more likely in fresh water

Question 3

What are the risk factors for drowning?

Answer 3

• children- male gender- intoxication- occupation/hobbies - fishing, scuba diving- medical conditions e.g epilepsy- open water conditions e.g. sea

Question 4

What is the immediate management of a drowning victim?

Answer 4

Pre-hospital:1. Removal from water - spinal injury risk in water is low2. Five rescue breaths prior to CPR

In Hospital:1. Resuscitation following ATLS protocolA&B:- secure airway- LPV- bronchoscopyC:- fluid resuscitation and vasopressorsD:- NeuroprotectionE:- temperature control to 34oC- empirical ABx

Consider ECMO as improved survival for patients who arrest and those who didn’t.

Question 5

What are poor prognostic indicators in drowning?

Answer 5

1. Submersion >5 mins2. pH <7.10 on arrival3. Cardiac arrest4. Delayed CPR5. Prolonged CPR

Question 6

Define hypothermia

Answer 6

Core body temp < 35oC:- mild 32-35- moderate 28-32- severe <28

Question 7

How is heat lost from the body?

Answer 7

5 routes:1. Radiation (40%)2. Convection (30%)3. Evaporation (15%)4. Conduction (5%)5. Respiration (10%)

Question 8

What may make a person become hypothermic?

Answer 8

1. Increased heat loss:- Surgery: open body cavity, skin exposure, cold table- trauma- Submersion/immersion- burns2. Impaired thermogenesis/thermoregulation:- Surgery: muscle relaxation, GA- Endocrine: hypothyroid- elderly- low body fat- alcohol- CNS pathology - hypothalamic impairment

Question 9

What are the complications of hypothermia?

Answer 9

1. Cardiovascular: - Catecholamine surge causes vasoconstriction, hypertension and tachycardia. - progressive/continued hypothermia causes bradycardia/bradyarrhythmias - Osborn J waves - asystole <20oC2. Respiratory: - respiratory depression3. Neurological: - CNS depression - coma and fixed and dilated pupils < 30oC - EEG isoelectric <20oC4. Endocrine/metabolic: - BMR drops 7% for every 1oC drop. - acidosis, hyperkalaemia, hypermagnesemia, hyperglycaemia.5. Haematological: - thrombocytopenia - bone marrow suppression - DIC - increased blood viscosity - impaired immunity

Question 10

How would you manage a hypothermic patient?

Answer 10

Resuscitation with an A-E approach: - Pulse check can be unreliable (echo may be required) - CPR should not be delayed - Up to three attempts at defibrillation for VF - delay further attempts until temp >30oC - avoid ALS drugs until temp >30 - not dead until ward (>32oC) and deadManage hypothermia (reward at 2-3oC / hour): - Passive: remove wet clothes and dry skin, increase ambient temp, blankets, encourage movement - Active external: forced air warmers, radiant heaters - Active internal: warm IV fluids, warm humidified gases, intravesical warm lavage, RRT, ECMO warming. - monitoring: oesophageal temp probe - serial ABGsManage complications of hypothermia (see question on complications)

Question 11

What are the complications of re-warming?

Answer 11

1. Cardiovascular: - dysrrhythmias - vasodilatation and hypotension (distributive shock & afterdrop) - cardiogenic shock2. Neurological: - seizures3. Metabolic/endocrine: - acidosis - hypoglycaemia - hyperkalaemia from reperfusion injury