Find information on thousands of medical conditions and prescription drugs.

Dysbarism

Dysbarism refers to medical conditions resulting from changes in ambient pressure. Various activities are associated with pressure changes. Scuba diving is the most frequently cited example, but pressure changes also affect people who work in pressurized environments (e.g. caisson workers), and people who move between different altitudes. more...

Home
Diseases
A
B
C
D
Dandy-Walker syndrome
Darier's disease
Dementophobia
Demyelinating disease
Dendrophobia
Dengue fever
Dental fluorosis
Dentinogenesis imperfecta
Dentophobia
Depersonalization disorder
Dermatitis herpetiformis
Dermatofibroma
Dermatographic urticaria
Dermatomyositis
Dermatophytosis
Desmoplastic small round...
Dextrocardia
Diabetes insipidus
Diabetes mellitus
Diabetes, insulin dependent
Diabetic angiopathy
Diabetic nephropathy
Diabetic neuropathy
Diamond Blackfan disease
Diastrophic dysplasia
Dibasic aminoaciduria 2
Diethylstilbestrol...
DiGeorge syndrome
Dilated cardiomyopathy
Diphallia
Diphtheria
Dipsophobia
Dissociative amnesia
Dissociative fugue
Dissociative identity...
Distemper
Diverticulitis
Diverticulosis
Dk phocomelia syndrome
Doraphobia
Double outlet right...
Downs Syndrome
Dracunculiasis
Duane syndrome
Dubin-Johnson syndrome
Dubowitz syndrome
Duchenne muscular dystrophy
Dupuytren's contracture
Dwarfism
Dysbarism
Dysgerminoma
Dyskeratosis congenita
Dyskinesia
Dysmorphophobia
Dysplasia
Dysplastic nevus syndrome
Dysthymia
Dystonia
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Medicines

Ambient pressure

Ambient pressure is the pressure in the water around the diver (or the air, with caisson workers etc). As a diver descends, the ambient pressure increases. At 10 meters (33 feet) in salt water, it is twice the normal pressure on land at sea level. At 40 meters (the recommended safety limit for recreational diving) it is 5 times the pressure at sea level.

Pressure decreases as we rise above sea level, but less dramatically. At 3000 feet altitude (almost 1000 meters), the ambient pressure is almost 90% of sea level pressure. Ambient pressure does not drop to 50% of seal level pressure until 20,000 feet or 6,000 meters altitude.

Effects of pressure on the body

Direct effects on tissues

This is not of practical importance, because the body is mostly composed of barely-compressible materials such as water. People often wonder whether scuba divers feel their body being crushed by the pressure. The answer is no. Divers would have to reach depths of thousands of feet before their flesh began to suffer significant compression.

Air spaces

Air is very compressible. Humans have many air spaces: sinuses, middle ears, gas in our bowels, cavities in our teeth, and largest of all, our lungs. On land in our daily lives, the pressure in our air spaces is usually exactly the same as the pressure outside, because our air spaces are connected to the outside world. If there was a pressure difference between the outside world and one of our air spaces, then we experience painful pressure on the walls of that air space, as air “tries” to get from the higher-pressure side to the lower-pressure side. This is why we sometimes get painful ears on air trips.

Dissolved gas

A percentage of the gas we breathe (air) is always dissolved in our blood, like the gas dissolved in a soda bottle with the lid on. If we move to a higher ambient pressure, then the gas we breathe is at a higher pressure, and more of it dissolves in our blood and body tissues. If we move back to a lower pressure, and we move slowly, then the extra gas comes out slowly until we are back to our normal amount of dissolved gas. But if we move quickly to a lower ambient pressure, then the gas comes out of our blood and tissues violently, in large bubbles, like to the difference between slowly opening a bottle of soda (dropping the pressure in the bottle slowly down to sea level), versus ripping the cap off quickly.

Types of dysbarism

Different types of illness result from increases in pressure (e.g. descent during a SCUBA dive, descent during a plane flight), versus decreases in pressure (e.g. coming up from a caisson, or ascending a mountain). Dysbarism comprises several types of illness:

Read more at Wikipedia.org


[List your site here Free!]


Dysbarism: A review of 35 cases with suggestions for therapy (Aeromedical reviews)

Early lesions of the labrum and acetabular cartilage in osteonecrosis of the femoral head
Osteonecrosis of the femoral head can be caused by a variety of disorders and affects the relatively young patient. Most studies have concentrated on ...
Insertion of temporary tympanostomy tubes for patients receiving hyperbaric oxygen therapy
Hyperbaric oxygen therapy (HBOT) is commonly used for a wide range of clinical conditions. The tympanic membranes are at risk of barotrauma during this ...

Home Contact Resources Exchange Links ebay