Post on 16-Jul-2015
transcript
Pressure at sea level is 760mmHg or 1Atm
For every 10M descent pressure increases
by 1Atm
Gases inhaled at high pressure to equalize
the external pressure on thorax so that
adequate expansion occurs
These inhaled gases at high pressure
dissolves in body fluids at high quantity
Inhalation of mixture of 80% Nitrogen and 20% oxygen at high pressure
Nitrogen narcosis at high pressure
Euphoria at 100 ft
Narcosis starts at 120 ft and 250ft (severe)
Narcosis because of anesthetic effect of nitrogen
Narcosis :- stage of unconsciousness and stupor
Advantages of heliox
narcotic effect of helium is one fifth of
nitrogen
reduces work of breathing due to low
resistance
less soluble
High pressure nervous syndrome due to
helium
HPNS is due to anesthetic effect of helium in
high pressure
Lipid soluble
Direct effect of helium in cns membranes
Drowsiness , tremors , in coordination
Eeg changes
Due to inhalation of 100% under high
pressure
Nausea , dizziness , irritability , disorientation
,disturbed vision , convulsions , pulmonary
damage
Aka dysbarism ,the bends , diver’s palsy ,
decompression sickness
Due to rapid shift of a person from a high
atmospheric pressure area to low pressure
area
Eg :- person working in caisson , deep sea
divers , or in unpressurized airplane cabinets
Decompression sickness (DCS) is
a condition that occurs when
divers come back to the surface
too quickly after being deep under
water. It is caused by the
formation of nitrogen bubbles in
the blood stream and, in the worst
cases, can cause death.
Divers breath 80% nitrogen under water
Nitrogen under such high pressure gets dissolved in blood
Gets accumulated in tissues and fats
During slow ascends these dissolved gas gets eliminated by lungs slowly
But rapid ascend causes formation of nitrogen bubbles
Which produces symptoms
Usually appear after half hour after reaching
sea level
Due to bubbles in musculoskeletal system
Bubbles in circulation to brain , spinal cord ,
heart
Bubbles in pulmonary circulation
Can be prevented by slow gradual ascend to
sea level
The reduction in pressure should not be
more than 50%
Hyperbaric chamber:
A sealed compartment used to treat
Air Embolism and decompression
sickness, in which pressure is first
increased and then gradually
decreased.
When diver suddenly returns to surface
holding breath
Air in the lungs increases causing expansion
and rupture of pulmonary veins
This occurs due to rapid loss of external
pressure on chest which leads to expansion
of gas inside lungs