 | Viet Tran Lung-related diving conditions - because they happen and they may not be DCI or barotrauma related |
Lung-related diving conditions - because they happen and they may not be DCI or barotrauma relatedRespiratory Issues In Diving
Drowning"A process resulting in primary respiratory impairment from submersion/immersion in a liquid medium. Implicit in this definition is that a liquid/air interface is present at the entrance of the victim's airway, preventing the victim from breathing air. The victim may live or die after this process, but whatever the outcome, he or she has been involved in a drowning incident"
- ILCOR, 2010
Sequence of Events
Aspiration volume & their consequences
Causes of 'silent' drowning
Predictors of Survival: Orlowski Score
Give 1 point for each of the following:
< 2 = 90% chance of complete recovery
> 3 = < 5% chance of complete recovery
Management
First Aid
Hospital
Clinical Features
Immediate
Subsequent Symptoms
Clinical Course
Treatment
Pulmonary OedemaImmersion Pulmonary Oedema
Swimming-Induced pulmonary oedema
Free diving pulmonary oedema
Scuba Diving Pulmonary Oedema
- Pulmonary Barotrauma see here
- Pulmonary DCS (The Chokes) see here
- Pulmonary Oxygen Toxicity see here
- Drowning Spectrum
- Salt Water Aspiration Syndrome (SWAS)
- Pulmonary Oedema
- Immersion Pulmonary Oedema
- Swimming
- Free diving
- Scuba Divers Pulmonary Oedema
- Immersion Pulmonary Oedema
- Underwater Blast
Drowning"A process resulting in primary respiratory impairment from submersion/immersion in a liquid medium. Implicit in this definition is that a liquid/air interface is present at the entrance of the victim's airway, preventing the victim from breathing air. The victim may live or die after this process, but whatever the outcome, he or she has been involved in a drowning incident"
- ILCOR, 2010
- Dry drowning no longer a 'thing' - it is a post mortem observation of lungs that have since resorbed water and appear 'dry'
Sequence of Events
- Initial submersion
- Voluntary breath-holding
- PCO2 reaches breaking point
- Inspiration with aspiration
- +/- laryngospasm
- +/- aspiration of vomitus
- Persistent hypoxaemia
- Death
- 3-4 min: Loss of consciousness
- 4-8 min: Cerebral hypoxia & death
Aspiration volume & their consequences
- 1-3 ml/kg = hypoxia
- > 11 ml/kg = blood volume displacement
- > 22 ml/kg = electrolyte derangement
- > 44 ml/kg = VF
- NB once respiration stops, no further water is aspirated
Causes of 'silent' drowning
- hyperventilating before breath-hold diving
- hypothermia/arrhythmia
- drugs & alcohol (incl nitrogen narcosis)
- diving illnesses
- water aspiration
- epilepsy (15x more likely to drown)
- Pneumonitis
- Pulmonary Oedema
- Bronchopneumonia
- Abscess/Empyema
- ARDS
- Hypoxic organ injury (esp brain)
Predictors of Survival: Orlowski Score
Give 1 point for each of the following:
- Age > 3 years
- Submersion > 5 min
- No resuscitation for > 10 min post rescue
- Comatose on admission to ED
- Arterial pH < 7.10
< 2 = 90% chance of complete recovery
> 3 = < 5% chance of complete recovery
Management
First Aid
- Rescue of a diver in water - see section later on
- Airway, Breathing, Circulation with emphasis on External Air Resuscitation
- EAR: 2 rescue breathes over 1-1.5s each, enough to see chest rise (~ 800ml). 12 breathes per min
Hospital
- Mild: asymptomatic, normal chest auscultation, Cxr, ABG = watch for 6 hrs and discharge with advice
- Moderate: mild hypoxaemia, no loss of consciousness, either chest auscultation or Cxr findings = admit overnight for O2 and observation +/- CPAP and reassess in the morning/becomes unwell
- Severe: have or will have an advanced airway, admit to ICU for ventilatory support
- Routine ABx not indicated
- Occurs due to aspiration of salt water (a hyperosmolar agent) causing an exudative process within alveoli
- Therefore occurs with snorkellers, divers, helicopter rescuers over see and swimmers
- Previously under recognised as a syndrome given often benign course
- Enough salt water aspiration was observed in a few scenarios
- Novice Navy divers undergoing strenuous water activities without an artificial breathing apparatus
- Old surface supply air regulators were not efficient and known to 'nebulise' salt water whilst diving
- Scenarios nowadays that can cause SWAS include:
- Over breathing the regulator (namely novice divers)
- Excessive resp flow eg anxiety, exercise
- Increased depth
- Re-insertion of regulator underwater (including buddy breathing)
- Damaged regulator, mouthpiece
- Being towed at speed
- Upstream regulator valves or air intake below exhaust
- removing the regulator on the surface
Clinical Features
Immediate
- Most divers will remember aspirating salt water after the fact
- Their initial complaint is usually a post dive cough +/- sputum +/- blood stained
Subsequent Symptoms
- Rigors, tremors, shivers
- Anorexia, Nausea, Vomiting
- Hot/Cold shivers
- SOB
- Cough
- Sputum production
- Malaise
- Headaches
- Generalised aches
Clinical Course
- Onset up to 2 hrs after being on land
- Lasting 1-24 hrs
Treatment
- Rest & O2 often all that is needed
- Otherwise supportive care
Pulmonary OedemaImmersion Pulmonary Oedema
Swimming-Induced pulmonary oedema
- Usually under extreme stress/exercise
- Due to a combination of increased cardiac output (exercise) + blood centralisation (immersion) + increase in pulmonary vascular resistance (cold) + increased perfusion in dependant areas of lung (eg lower lung in side-stroke swimming) +/- over-hydration
- Histologically due to capillary stress failure (no inflammation)
- Treatment is supportive, resolving < 24 hrs
Free diving pulmonary oedema
- Due to alveoli capillary stress eventually leading to rupture within alveoli
- As the free-diver enters the water, blood centralisation occurs, increasing preload
- As the free-diver descends, it is possible to for their lung volume to reduce beyond functional residual capacity
- Should this occur, further centralisation of blood occurs
- Eventually the amount and pressure of blood contributing to preload will overwhelm the alveoli capillary wall stress causing it to rupture
Scuba Diving Pulmonary Oedema
- Exercise is not a provoking feature (unlike immersion pulmonary oedema)
- Onset can occur when reaching shallow depths/ascent and resolve within minutes to hours
- Mechanism of action is unclear but probably a combination of:
- Cold-induced hypertensive pulmonary oedema
- Blood centralisation
- Negative pressure (Partial pressure at lips is less than in the alveoli)
- head out/thorax in water
- inspiring against resistance
- reduced gas supply
- increased gas density with depth
- increased ventilation
- counter-lung above the diver
- equipment such as over inflated BCD, tight wetsuit
- Exertion
- Stress
- Aspiration
- Treatment remains supportive
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