Background
• Atmospheric pressure at sea level = 760 mmHg = 14.7 psi: 1 atm
• Each descent of 33 ft under water ↑ pressure by 1 atm
• Dive tables & computers set standards for rate & depth of ascent to avoid dysbarism
Approach
• Careful hx: Length, depth, # of dives, interval btw dives, comorbid dz, sinus pain during dive, intoxication, onset of sxs, dive relative to decompression limits
• Divers Alert Network, Duke University (919) 684-8111, 24-h med advice
DECOMPRESSION SICKNESS (DCS)
History
• Improper dive time, depth, & ascent; sx can develop during or after (1–24 h) ascent, longer if air travel
Findings
• Fatigue, AMS, visual defects, lingual pallor, tachypnea, tachycardia, N/V, ↓ UOP, sz, neuro Δ, joint pain, lymphedema, pruritus
Evaluation
• Cardiac monitor, CBC, CMP, O2 sat, tox screen, CO level, coags, CXR, head CT
Treatment
• 100% O2 (NRB mask), place pt in left lateral decub & mild Trendelenburg, hyperbaric oxygen, IVF (UOP 1.5 mL/kg/h) for recompression
• Goal of recompression to ↓ mechanical obstruction of air bubbles, ↑ tissue O2 delivery
• Sx tx: Intubation (inflate cuff w/ saline), needle decompression, sz control
Disposition
• Ground transport, or low-flying air transport (cabin pressure <1000 ft)
• Admit to institution w/ hyperbaric oxygen capability
Pearls
• Spectrum of illness: Formation of small nitrogen gas bubbles in blood & tissues
• Depends on location & degree of bubble formation
• ↑ freq w/ longer & deeper dives, comorbid illness (COPD, CAD, PFO, asthma)
• Residual paralysis, myocardial necrosis, other ischemic injuries possible; early recognition & tx imperative
• Wait >12–48 h btw diving & flying, no diving for 7 d after DCS I, 28 d after DCS II
MIDDLE EAR BAROTRAUMA
History
• Usually occurs on descent; ↑ pain w/ ↑ water pressure on TM, equilibration via eustachian tubes, rupture occurs b/w 5–17 ft → pain relief; vertigo, nausea, vomiting, hearing loss
Findings
• Reversible Bell’s palsy from increased pressure to facial nerve in severe cases
Evaluation
• Concomitant eval for inner ear barotrauma
Treatment
• Nasal vasoconstrictor drops/spray to open fluid from middle ear; antihistamines, analgesia, pinch nose & swallow to displace fluid through eustachian tube
Disposition
• ENT f/u 2 wk
Pearl
• No benefit w/ abx; use occlusive earplugs when diving/showering until TM healed
