Dysbarism Flashcards
What is Henry’s law?
At constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid
What is Dalton’s law?
The pressure of a mixture of gases simply is the sum of the partial pressures of the individual components
What is Boyle’s law?
The volume of a given mass of has is inversely proportional to its pressure, if the temperature remains constant
What is Charle’s law?
The volume of a gas is directly proportional to the temperature if the pressure remains constant
How much does the effective atmospheric pressure increase for each 10 metres of descent?
1 atmosphere, or 100kPa
What is decompression sickness?
When breathing air under pressure, body tissues become saturated with the dissolved inert gas component, usually nitrogen. The amount absorbed depends on the time and depth of the dive and, if the ascent is too rapid, the gas comes out of solution and forms bubbles.
What is an air gas embolism?
Expanding gas within the alveoli cause pulmonary barotrauma, rupturing the capillary walls and allowing bubbles to enter the arterial circulation. This can result from bolting to the surface, breath holding during an ascent, or airway obstruction from pre-existing pulmonary pathology.
Whatever their source, the bubbles can cause pain and damage by distorting tissues; distal ischaemia by obstructing blood vessels; and initiate biochemical processes, such as platelet activation and leucocyte adhesion.
What are the risk factors for air gas embolism/decompression sickness?
- Repetitive dives with reduced surface intervals
- Sawtoothdive profiles or heavy exertion
- Inexperience or poor physical condition
- Alcohol, drugs, or dehydration
- Prior history of DCI or other medical conditions
What are the signs/symptoms of decompression sickness?
Neurological - Seizure - Unilateral motor/sensory deficit - Paralysis - Unconsciousness Respiratory - Breathlessness/chest pain - APO - Pneumothorax, subcutaneous emphysema Cardiac - Chest pain - Cardiac arrest Localised symptoms - Skin itch - Joint pain (the bends)/ tremors
Describe the management of decompression sickness
- Oxygen (IPPV)
- IV fluid
- LMA/ETT
- Maintain normothermia
- Analgesia
- Recompression
- Take the pt’s dive computer and gauges with them
What is altitude sickness?
The effects of chronic exposure to the decreased partial pressure at altitude
At what height is altitude sickness seen?
Above 2500m
What are the signs/symptoms of acute mountain sickness (AMS)?
- Headache
- Nausea
- Vomiting
- Dizziness
- Fatigue
- Dry cough
- Loss of appetite
- Disturbed sleep
- General malaise
What are the signs/symptoms of high altitude cerebral oedema (HACE)?
- Ataxia/staggering gait
- Confusion
- Hallucinations
- Memory loss
- Impaired judgement
- Psychotic behaviour
- Coma
What are the signs/symptoms of high altitude pulmonary oedema (HAPE)?
- SOB
- Chest tightness
- Weakness
- Cough
- Frothy blood-streaked sputum
- Tachycardia
- Tachypnoea
- Cyanosis
