BAROTRAUMA Flashcards
RED FLAGS
- Neuro: headache, visual changes, motor/sensory deficits, cranial nerve palsies, seizures, paralysis, ALOC.
- Resp: dyspnoea, haemoptysis, chest pain, APO, pulmonary barotrauma (pneumothorax, subcutaneous emphysema, pneumomediastinum).
- CV: chest pain, arrest.
- Other: joint pain, itchiness, rash, tremors.
DIFFERENTIALS
- PE
- ACS
- ARDS
- AGE
CAUSE
Rapid ascent in diving, COPD or asthma causing.
LAWS
Dalton’s: total atmospheric pressure (P) = sum of the partial pressure (PP) of dissolved gasses. When you descend, that atmospheric P doubles –> PP doubles. This relates to the increase in P as you descend.
Henry’s (coke bottle): in a container with air & liquid, gas dill diffuse equally between the two.
- Decent: P increases –> gas moves down its concentration gradient –> dissolving into bloodstream.
- Ascent = opposite.
- Quick ascent –> nitrogen hasn’t enough time to diffuse out of lungs –> forms bubbles –> the bends + DCS. This relates to the bends where gases will dissolve equally between liquid & tissue.
Boyle’s: volume (V) & P are inversely proportional –> an increase in one causes a decrease in the other.
- Descent: decrease V –> increase P
- Ascent: decrease P –> increase V
- Quick ascent holding breath –> overinflation –> burst/barotrauma –> pneumothorax, AGE (ASC, Stroke). Air pockets can over expand & cause barotrauma (sinuses, dental fillings, middle ear –> infection). Air P in plural space is greater than in the lung itself –> pneumothorax. If barotrauma has caused a flap/one-way valve –> tension pneumothorax.
MANIFESTATIONS
- DCS/the bends: joint & muscle ache, numbness, weakness, rash.
- Simple/tension pneumothorax: SOB, tachycardia, chest pain –> decompensate = hypotension, ALOC, cardiac arrest, subcutaneous emphysema, raised JVP.
- AGE + CAGE (stroke, ACS): headache, visual disturbance, hemiplegia, seizure, coma, death. Or chest pain, radiating, haemoptysis, dyspnoea.
TREATMENT
PRIMARY
- D: remove from water/dry.
- R:
- A: advanced airway
- B: 100% O2 (accelerate reabsorption of nitrogen), chest decompression if tension pneumothorax (release P in pleural space that is forcing the mediastinum to opposite side & crushing the heart).
- C: IV access + fluids (divers are often dehydrated –> increase blood volume).
- D (drugs): O2, analgesia.
- E: Remove wetsuit + maintain normothermia, position Pt. supine (nitrogen rises if standing up, also prevents AGE from becoming CAGE). Contact Divers Alert Network (DAN).
Secondary Survey: Thorough RSA, CVA, NSA + reassessments.
PARAMEDIC ROLE
- To record diving Hx, maximise oxygenation & nitrogen diffusion, facilitate transport to hospital with a hyperbaric chamber, & pain relief.
PHARMACOLOGY
Fentanyl
Mu (opioid) receptor agonists which reduce GABAergic neurotransmission & increase parasympathetic activity. GABA release –> hypopolarisation –> CNS depression, activation of dopaminergic pathways –> change perception/disassociation from pain + euphoria. The inhibition of nociceptive afferent neurons in the PNS impairs transmission of pain messages.
- Side effects: (Boy Does He Need Pain Relief) bradycardic, drowsy, hypotensive, nausea, pinpoint pupils, respiratory depression.
DEFINITIVE CARE
- Neuro exam, chest radiography to assess for barotrauma & extent of damage (pneumothorax).
- Test blood for dissolved gasses, troponin (ACS).
- Spirometry to assess lung filling & function.
Treatment
- Mechanical ventilation
- Hyperbaric chamber: 100% O2 in a pressurised chamber for several hours –> increase O2 solubility & nitrogen washout, decreases the size of gas bubbles –> decrease tissue ischemia in all forms of AGE.
- Sinus squeeze treated with decongestants.