Altitude Flashcards
How does the body adapt to hypoxic environments?
- Through hyperventilation
- The increased production of RBC
- Increased capacity of the lungs to diffuse
- Increase vascularity of tissue
What are the three types of altitude sickness?
- Acute Mountain sickens (AMS)
- High-Altitude cerebral Oedema (HACE)
- High-Altitude pulmonary Oedema (HAPE)
Signs and symptoms of early/mild Acute Mountain Sickness?
- Feeling of hangover
- Headache
- Nausea and vomiting
- Weakness
- Normally self-limiting
- Insomnia
Signs and symptoms of late/severe Acute Mountain Sickness?
- Dyspnoea
- Vomiting
- ACS
- Headache
- Ataxia
- Retinal Haemorrhage
- May progress to HACE or HAPE
Acute mountain sickness, how does it affect the body?
- Acute mountain sickness is caused due to the rate and height of ascent. It is not related to fitness or gender.
Explain the pathophysiology of High Altitude Cerebral Oedema.
- As there is an increase in ICP this causes decreased CPP that results in death
- This is due to vasogenic oedema
- And as hypoxia sets in it results in an increase in extracellular fluid + micro vascular permeability.
What are the signs and symptoms of High Altitude Cerebral Oedema?
- Progressive decline in mental status
- Truncal ataxia
- Cranial nerve palsies
- SOB
- Fatigue
What are the treatments for high altitude cerebral oedema?
- Stop the climb, and then proceed with a rapid controlled descent.
- Dexamethasone to decrease capillary permeability and decrease ICP
- Oxygen 2-4L/min and then hyperbaric treatment
What is the cause of non-cardiogenic pulmonary oedema?
- A rise in pulmonary artery pressure
- There is an increase in arterial pressure this result in hydrostatic overcoming oncotic pressure that causes a fluid shift into the interstitial space.
Who is more susceptible to high altitude pulmonary oedema?
- Those with underlying respiratory or cardiac pathologies.
What are early signs of high altitude pulmonary oedema?
- Fluid in interstitial space
- Dry cough and decreased exercise tolerance
What are late signs of high altitude pulmonary oedema?
- Tachycardia
- Increasing dyspnoea
- Marked weakness
- Productive cough and frothy sputum and cyanosis
What is the primary cause of barotrauma?
- Develops due to breathing gases at higher than normal atmospheric pressure
For every ten meters below sea level?
- It drops 1 ATA
List the forms of trauma caused by Pulmonary Barotrauma?
- Pneumothorax caused by rapid ascent, breathe holding or breathing compressed air.
- Alveolar rupture can allow air into the pulmonary circulation, causing arterial gas embolism.
- May cause lung tissue damage and emphysema
What are signs and symptoms of Pulmonary Barotrauma?
- Chest pain
- Difficulty breathing
- Coughing
- Blueness of lips and tongue (cyanosis)
- Voice change
- Difficulty swallowing
- Crackly skin around neck
- Reduced responsiveness
- Signs/symptoms of decompression illness may also present
Signs and symptoms of nitrogen narcosis?
- Light headedness
- Inattention
- Difficulty concentrating
- Poor judgment
- Anxiety
- Decreased coordination
- Hallucinations
- Coma, may lead to death
How does decompression illness occur?
- Ambient pressure increases as divers descend; this increases the partial pressure of nitrogen which is dissolved into body fluids.
How does a slow ascent result in off gassing?
- A slow ascent will decrease the ambient pressure
- Decrease the partial pressure of nitrogen
- The above results in tissue super-saturation which is overcome by excess moving to the lungs and being eliminated. This is off gassing.
What does a Fast Ascent cause?
- Nitrogen bubbles will form in the venous, arterial, lymphatic system or in the tissues themselves.
List signs and symptoms of decompression illness?
- Musculoskeletal pain
- Itching
- Respiratory complaint
- Neurological changes
What is the primary goal in the treatment of the patient with Decompression Illness?
- To allow nitrogen to off-gas, increasing 02 delivery and allowing the lungs to rehydrate
What position must patients with DCI be kept in and why?
- In the supine or lateral position at all times to prevent nitrogen bubbles from moving upwards.
What amount of fluids should be administered to the DCI patient regardless of perfusion status?
- 1L over 15 – 20 min to rehydrate patient, unless chest is unclear.
- We are aiming to rehydrate the patient due to the potential fluid shift DCI can cause.
Why is the aim to keep a patient
- Because higher than this has the potential to undissolved already dissolved nitrogen bubbles.
If opioid analgesia is indicated why must you consult before giving?
- Opioids may mask symptoms of DCI and may interfere with the potential for recompression.
What are some specific diving Hx that are important?
- Number of dives preformed
- Surface interval between dives
- Type of ascent
- Depth of dive
- Breathing gas mixes used
- Level of exertion before and after dive
What are some good indicators for a positive outcome of a drowning victim?
- Less than five minutes submersion
- Higher GCS post-drowning
- Initiation of good quality CPR within 10 minutes
- First spontaneous breath within 30 minutes
What are the primary causes of morbidity and death from drowning?
- Hypoxaemia and acidosis that result in cardiac arrhythmia and brain death.
What are some other determinates that impact the ultimate outcome of a drowning victim?
- The type of fluid drowned in
- The temperature of the water
- Use of drugs and alcohol
- Mammalian diving reflex – overrides the homeostatic reflexes
- Medical complications /history
- General factors
What is the difference between a salt water and Freshwater drowning?
- Fresh water is a hypotonic solution and dilutes the surfactant causing alveolar collapse
- Salt water is a hypertonic solution that pulls fluid into the alveoli causing pulmonary oedema
- Both of these lead to an intrapulmonary shunt and a V/Q mismatch
- This then leads to hypoxia
If positive outcomes are seen in the drowning Pt what outcomes may they see later on?
- Respiratory infections
- Acute respiratory distress syndrome
- Pneumonia
What injuries may affect the CNS that can determine Pt outcome and ongoing morbidity?
- Tissue hypoxia
- Ischemia
- Raised ICP
- Cerebral oedema
- Neuron cell damage
What primary affects are seen on the myocardial system in the submersion patient and what are their causes?
- Myocardial dysfunction and arrhythmia secondary to hypothermia, hypoxemia, acidosis and electrolyte imbalance.
- More likely to see sinus brady, PEA and AF then VF or asytole.
What factors may suggest a pt has aspirated?
- Porloged immersion time
- Any LOC
- Manual ventilations
- Cough
- CPR required
- GCS <5
- Cyanosis
- Tachycardia
- Wheeze/crackles on auscultation
- Pink, frothy sputum
- Altered conscious state
- Decreased Sp02 readings
How is mammalian diving reflex caused? And what is its aim?
- It is caused by cooling the forehead
- And is aimed at optimising respiration when submerged.
What are the resulting signs and symptoms of Mammalian diving reflex?
- Bradycardia
- Peripheral vasoconstriction
- Bradypnoea
- Movement of blood to the core, this helps maintain higher core temperatures longer and initiates a bolus of oxygenated blood to vital organs prior to cardiac arrest
What is immersion syndrome and what is believed to be the cause?
- Sudden cardiac arrest following cold water immersion.
- Caused by a vagal response coupled with vasoconstriction
What is recovery syncope?
- It may occur following the removal from cold water.
- The loss of external water pressure leading to reduced central perfusion.
