HYPEROXIA AND
HYPERBARIA
HYPEROXIA
(BREATHING OXYGEN ENRICHED AIR)
BREATH-HOLDING EXERCISE
• BENEFICIAL EFFECTS DURING BREATHHOLDING EXERCISE DUE TO THE
INCREASED CARBON DIOXIDE AND
HYDROGEN IONS CONCENTRATIONS
THAT ARE EXPIRED PRIOR TO EXERCISE
(HALDANE EFFECT) THEREBY REDUCING
RESPIRATORY STIMULATORS AND THE
DESIRE FOR RESPIRATION
• INCREASED PERFORMANCE TIME DURING
BREATH-HOLDING EXERCISE
NORMAL (BREATHING O2) EXERCISE
• DURING SUBMAXIMAL EXERCISE:
- LOWER HEART RATE
- LOWER BLOOD LACTATE
ACCUMULATION
- LOWER VENTILATION RATE
- INCREASED WORK TIME TO
EXHAUSTION
• DURING MAXIMAL EXERCISE:
- GREATER ENDURANCE CAPACITY
- INCREASED WORK TIME TO
EXHAUSTION
NORMAL (BREATHING O2) EXERCISE
• BENEFITS RELATED TO THE INCREASED
PARTIAL PRESSURE OF OXYGEN, WHICH
INCREASES THE OXYGEN TRANSPORTED
BY HEMOGLOBIN AND DISSOLVED IN THE
PLASMA (PHYSICAL SOLUTION) AS WELL
AS INCREASES THE DIFFUSION OF
OXYGEN ACROSS THE ALVEOLARCAPILLARY AND MUSCLE TISSUECAPILLARY MEMBRANES
OXYGEN-BREATHING DURING
RECOVERY
• MINIMAL EFFECTS ON EITHER THE
RECOVERY PROCESS OR ON SUBSEQUENT
WORK BOUT PERFORMANCES
• NO PHYSIOLOGICAL BASIS FOR THE USE
OF OXYGEN DURING RECOVERY
ALTHOUGH THERE MAY BE A
PSYCHOLOGICAL EFFECT
HYPERBARIA
HISTORY OF UNDERWATER
SUBMERSION
HYPERBARIA
• FOR EVERY DECREASE OF 10
METERS IN SEA WATER AND 10.4
METERS IN FRESH WATER,
PRESSURE INCREASE BY ONE
ATMOSHPHERE (1 ATM) OR 760
mmHG
• OPEN-CIRCUIT SCUBA (SELFCONTAINED UNDERWATER BREATHING
APPARATUS) IS THE MOST WIDELY
USED APPARATUS BY DIVERS
• SCUBA USES MIXED GASES WHICH ARE
SUPPLIED TO THE LUNGS AT A
PRESSURE EQUIVALENT TO AMBIENT
(SURROUNDING) PRESSURE
• SCUBA HAS INCREASED THE DEPTH
AND DURATION OF DIVING
• HOWEVER, THE
MOST COMMON
WAY TO ENTER
THE WATER IS
BREATH-HOLD
DIVING FOR
DURATIONS UP TO
3 MINUTES OR
LONGER AND
DEPTHS UP TO 70
METERS OR MORE
IMPORTANT LAWS FOR
UNDERSTANDING THE
EFFECTS OF HYPERBARIA
ON THE HUMAN BODY
• BOYLE’S LAW - PRESSURE AND VOLUME
OF A GAS ARE INVERSELY RELATED
•
•
INCREASE PRESSURE, DECREASE VOLUME
DECREASE PRESSURE, INCREASE VOLUME
• CHARLE’S LAW - ASSUMING PRESSURE
REMAINS CONSTANT, THE VOLUME OF A
GAS IS PROPORTIONAL TO ABSOLUTE
TEMPERATURE OR IF VOLUME REMAINS
CONSTANT, PRESSURE IS DIRECTLY
PROPORTIONAL TO ABSOLUTE
TEMPERATURE
• DALTON’S LAW - THE TOTAL PRESSURE
EXERTED BY A MIXTURE OF GASES IS
EQUAL TO THE SUM OF THE INDIVIDUAL
PRESSURES EXERTED BY EACH OF THE
GASES COMPRISING THE GAS MIXTURE
• PB = PO2 + PCO2 + PN2 +Pother gases
• THE AMOUNT OF GAS THAT A FLUID WILL
ABSORB UNDER PRESSURE VARIES IN
DIRECT PROPORTION TO THE PARTIAL
PRESSURE OF THE GAS
• HENRY’S LAW - FOR A GAS OF LOW
SOLUBILITY (DECREASED LIKELIHOOD OF
BEING DISSOLVED AND THEREFORE CAN
SATURATE TISSUES) , AT A GIVEN
TEMPERATURE THE CONCENTRATION IN
THE LIQUID WILL BE NEARLY
PROPORTIONAL TO THE PRESSURE OF
THAT GAS IN THE GAS PHASE
• GASES WITH LOW SOLUBILITY REQUIRE
LESS TIME TO SATURATE A LIQUID THAN
GASES OF A HIGHER SOLUBILITY
• THE LONGER AND DEEPER THE DIVE, THE
GREATER THE SATURATION OF THE
BODY’S TISSUES WITH GASES
BREATH-HOLD (BH) DIVING
• AS ONE DESCENDS THE INCREASE IN
PRESSURE IS EVENLY TRANSMITTED
THROUGHOUT THE BODY’S TISSUES
COMPRESSING COMPLIABLE GAS
CONTAINING CAVITIES (BOYLE’S LAW)
• GASTROINTESTINAL TRACT IS VERY
COMPLIANT OR COMPRESSIBLE
• IN THE AIRWAYS, LUNGS, SINUSES, AND
MIDDLE EAR, THE INTERNAL PRESSURE IS
EQUALIZED WITH AMBIENT PRESSURE BY
VENTING AIR BETWEEN THE
COMPRESSIBLE (LUNGS) AND
NONCOMPRESSIBLE CAVITIES.
• GENERALLY, THE VASCULATURE IS
IN EQUILIBRIUM WITH EXTERNAL
PRESSURE
• VESSELS WHICH PASS THROUGH
INTERNAL CAVIITIES WITH LOWER
PRESSURE MAY RUPTURE CAUSING
HEMORRHAGING
• BAROTRAUMA (INJURIES
RESULTING FROM PRESSURE
DIFFERENCES ACROSS THE WALLS
OF GAS-FILLED CAVITIES) MAY
CAUSE PAIN AND TISSUE DAMAGE
• AS THE DEPTH OF
THE DIVE
INCREASES, LUNG
VOLUME TENDS
TO DECREASE
• AT ABOUT 20
METERS LUNG
VOLUME TENDS
TO EQUAL
RESIDUAL
VOLUME
• BELOW 20 METERS THERE IS AN
INCREASED LIKELIHOOD THAT
PULMONARY VESSELS MAY RUPTURE
CAUSING CONGESTION, EDEMA, AND
HEMORRHAGING
• DURING BH DIVING THE LOWER
INTRAHORACIC PRESURE MAY RESULT IN
AN INCREASE IN BLOOD FLOW TO THE
THORACIC CAVITY AND THE DIAPHRAGM
MAY BECOME DISPLACED TOWARD THE
HEAD THEREBY FURTHER REDUCING
LUNG VOLUME (AND HENCE INCREASING
PRESSURE DUE TO BOYLE’S LAW) AND
PREVENTING THE RUPTURE OF
PULMONARY VESSELS
• AT SEA LEVEL, BREATH HOLDING:
• DECREASED ARTERIAL AND
ALVEOLAR PO2
• INCREASED ARTERIAL AND
ALVEOLAR PC02
• INCREASED ARTERIAL PC02 AND
DECREASED ARTERIAL P02
EVENTUALLY STIMULATES
VENTILATION (BREATHING)
BREATH-HOLD DIVING
• DURING THE DESCENT
BOTH ALVEOLAR PO2
AND PCO2 INCREASE
DUE TO BOYLE’S LAW
• INCREASED
ALVEOLAR PC02 MAY
REVERSE THE
GRADIENT BETWEEN
THE LUNGS AND
BLOOD AND CO2 MAY
MOVE BACK INTO THE
BLOOD
• MAXIMUM ALVEOLAR P02
VALUE ACHIEVED IS
DEPENDENT ON A HIGH
INITIAL SURFACE VALUE,
LOW METABOLIC RATE,
GREATER DEPTH OF DIVE,
AND DURATION/QUICKNESS
OF DESCENT
• QUICKER THE DESCENT,
THE HIGHER THE PO2
VALUE ACHIEVED AND
DEPLETION OF O2 IS
MINIMIZED
• AT THE BOTTUM
OF THE DIVE, O2
MOVES OUT OF
THE LUNGS AT A
RATE DICTATED
BY METABOLIC
DEMANDS AND
ALVEOLAR PCO2
TENDS TO
EQUALIZE WITH
ARTERIAL PCO2
• DURING THE ASCENT,
ALVEOLAR P02
DECREASES WHICH MAY
STOP THE DIFFUSION OF
O2 INTO THE BLOOD
• ALVEOLAR PC02 ALSO
DECREASES WHICH
WILL INCREASE THE
TRANSFER OF CO2 FROM
THE BLOOD INTO THE
LUNGS AND MAY LEAD
TO A DECREASE IN
VENTILATORY DRIVE
MAXIMUM DURATION OF A BH DIVE (RANGE FROM 20-270 SECONDS)
CAN BE INCREASED BY:
• PSYCHOLOGICAL FACTORS
• LARGE LUNG VOLUME AND HIGH ALVEOLAR AND ARTERIAL PO2
LEVELS
• LOW ARTERIAL PC02 AS PCO2 STIMULATES RESPIRATION
• REDUCED METABOLIC RATE ALTHOUGH PHYSICAL MOVEMENT
MAY CAUSE CONSCIOUS DISSOCIATION AND THUS DELAY THE
BREAKING POINT
• INCREASED PRESSURE WHICH WILL INCREASE ALVEOLAR AND
ARTERIAL O2 WHICH INCREASES TOLERANCE TO HYPERCAPNIA
• INHALATION OF OXYGEN ENRICHED GAS PRIOR TO DIVE
• HYPERVENTILATION PRIOR TO DIVE WHICH WILL DECREASE
ALVEOLAR AND ARTERIAL PCO2 LEVELS AND HENCE
VENTILATORY DRIVE; MAY BE DANGEROUS AS LIKELIHOOD OF
HYPOXIA TO THE BRAIN IS INCREASED, PARTICULARLY DURING
THE ASCENT PHASE OF THE DIVE WHEN THERE IS ALREADY
DECREASED MOVEMENT OF OXYGEN INTO THE BLOOD
METABOLIC, CARDIAC, AND CIRCULATORY
FUNCTION DURING BH DIVING
• NO CHANGE IN OXYGEN UPTAKE RATE, CARDIAC
OUTPUT, AND OXYGEN EXTRACTION
• BRADYCARDIA DUE TO INCREASED VAGUS
DOMINANCE OF HR AS PNS IS STIMULATED BY
COLD WATER AND APNEA
• INCREASED STROKE VOLUME DUE TO
ENHANCED VENOCONSTRICTION AND RETURN
OF BLOOD FLOW THEREBY INCREASING ENDDIASTOLIC VOLUME
• INCREASED PERIPHERAL VASOCONSTRICTION
(26-53%) WHICH INCREASES BLOOD PRESSURE
• INCREASED VENOCONSTRICTION AND
VASOCONSTRICTION DUE TO INCREASED SNS
RELEASE OF NOREPINEPHRINE
ADAPTATIONS TO BH DIVING
• REPEATED EXPOSURE TO HIGH
PRESSURE, HYPOXIA, AND
HYPERCAPNIA REDUCES THE STRESS OF
BH DIVING AND ENHANCES DIVING
PERFORMANCE
• REDUCED STRESS OF BH DIVING AND
ENHANCED DIVING PERFORMANCE ARE
DUE TO:
• INCREASED VITAL CAPACITY AND DECREASED
RESIDUAL LUNG VOLUME THEREBY INCREASING
THE RATIO OF TOTAL LUNG CAPACITY TO RESIDUAL
LUNG VOLUME RESULTING IN GREATER LUNG
COMPLIANCE
• INCREASED STRENGTH IN THE RESPIRATORY
MUSCLES (DIAPHRAGM AND EXTERNAL
INTERCOSTALS)
• DECREASED CHEMOSENSITIVITY TO HYPERCAPNIA
AND POSSIBLY HYPOXIA THEREBY DECREASING
VENTILATORY DRIVE (I.E., RESPIRATION)
• INCREASED BRADYCARDIA WHICH DECREASES
MYOCARDIAL OXYGEN REQUIREMENTS
PHYSIOLOGICAL PROBLEMS
ASSOCIATED WITH DEEP
AND LONG DIVES
OXYGEN POISONING
• OCCURS WHEN PARTIAL PRESSURE OF INSPIRED
OXYGEN EXCEEDS 570 mmHG (2.6 ATA OR 26 METERS)
• ADVERSE PULMONARY EFFECTS (EDEMA,
CONGESTION, INFLAMMATION, ATELECTASIS
(COLLAPSE OF LUNGS), FIBRIN FORMATION,
PNEUMONIA, BRONCHITIS, BRONCHIECTASIS,
DEGENERATION OF ALVEOLAR CELLS, AND SCLEROTIC
CHANGES IN PULMONARY ARTERIOLES) BEGIN AT PIO2
OF .5 ATA OR APPROXIMATELY 22-26 METERS
• ADVERSE CENTRAL NERVOUS SYSTEMS EFFECTS
(TWITCHING OF FACE AND HAND MUSCLES, TETANUS
IN MAJOR MUSCLE GROUPS, UNCONSCIOUSNESS, AND
CONVULSIONS) BEGIN AT PIO2 OF 2.0 ATA OR
APPROXIMATELY 90-100 METERS
NITROGEN NARCOSIS RESULTING FROM
EXPOSURE TO COMPRESSED AIR
• EUPHORIA, HYPEREXCITABILITY,
IMPAIRED INTELLECTURAL FUNCTION
(PERCEPTION AND MEMORY), IMPAIRED
NEUROMUSCULAR FUNCTION
• ALTHOUGH EFFECTS HAVE OCCURRED AT
DEPTHS OF 30 METERS, THE EFFECTS
TEND TO INCREASE AS PRESSURE
INCREASES; 90 METERS HAS BEEN SET AS
A PRACTICAL LIMIT FOR AVOIDANCE OF
NITROGEN NARCOSIS
• HIGH PRESSURE NERVOUS SYNDROME
(HPNS) IS FOUND IN DIVES DEEPER THAN
18 ATA OR 170 METERS AND TENDS TO
INCREASE AS THE DEPTH OF THE DIVE
INCREASES
• DIZZINESS, NAUSEA, VOMITTING, BODY
TREMORS, CHANGED EEG ACTIVITY, AND
INCREASED DAYTIME SLEEP
• HPNS IS DUE TO GENERAL NEURONAL
HYPEREXCITABILITY IN RESPONSE TO
HYDROSTATIC PRESSURE AFFECTING
NERVE CELL MEMBRANES
• DECOMPRESSION SICKNESS
RESULTS FROM NITROGEN (N2)
ABSORPTION BY THE TISSUES OF
THE BODY, PARTICULARLY DURING
LONGER AND DEEPER (HENRY’S
LAW) DIVES
• TISSUES OF THE BODY CAN BE MORE
EASILY SATURATED THAN
DESATURATED
• HIGH PN2 RESULTS IN
SUPERSATURATION OF TISSUES
WITH N2
• DURING DECOMPRESSION BUBBLES OF
GAS ARE FORMED IN THE BLOOD
LEADING TO DECOMPRESSION SICKNESS
(THE BENDS) AS THE N2 SLOWING LEAVES
THE BODY’S TISSUES DURING
DESATURATION
• VENOUS BUBBLES ARE NOT A MAJOR
PROBLEM BUT ARTERIAL BUBBLES
CAUSE NEUROLOGICAL SYMPTOMS SUCH
AS SKIN RASH, MUSCLE AND JOINT
DISCOMFORT, PARALYSIS, NUMBNESS,
HEARING LOSS, VERTIGO, CHOCKING,
CHEST PAIN, UNCONSCIOUSNESS, AND
POSSIBLY DEATH
DECOMPRESSION TABLES HAVE BEEN
DEVELOPED BASED ON THE DEPTH AND
LENGTH OF DIVE
• ONCE TISSUES ARE SATURATED
WITH INERT GASES, CONTINUED
EXPOSURE TO INCREASED PRESSURE
WILL NOT INCREASE THE TIME
REQUIRED FOR DESATURATION
• HENCE, DIVERS CAN STAY DOWN IN
WORK HABITATS OR SURFACE
CHAMBERS FOR LONG PERIODS TO
COMPLETE WORK OR A MISSION
AND UNDERGO DECOMPRESSION
ONLY ONCE AT THE END OF THE
MISSION
• SATURATION
EXCURSION DIVING
INCREASES THE
LIKELIHOOD OF
DEVELOPING O2
POISONING IF THE
PARTIAL PRESSURE
OF INSPIRED OXYGEN
(PIO2) EXCEEDS 0.5
ATA
• THEREFORE, THE USE
OF O2 COMPRESSED
AIR IN SATURATION
DIVING VEHICLES
AND HABITATS IS
LIMITED TO DEPTHS
LESS THAN ABOUT 22
METERS
• IN SATURATION
DIVING VEHICLES
AND HABITATS AT
DEPTHS GREATER
THAN ABOUT 22
METERS, NITROX,
HELIOX, AND
TRIMIX
BREATHING GASES
ARE USED TO KEEP
THE PIO2 BELOW .5
ATA THEREBY
AVOIDING O2
POISONING
• WHICH MAMMAL IS CONSIDERED TO
HAVE THE GREATEST DIVING
CAPABILITIES?
Sea Elephant?
OR ELEPHANT SEAL?
QUESTIONS??
Volcanoes of the Deep Sea
What are some of the major
environmental factors challenging
the existence of life in the deep sea?
What are some of the uses of the
knowledge gained from the study
of life existing in the deeper depths
of the ocean?
CLEANING THE AIR
NBC DATELINE
STONE PHILLIPS
• THE AIR IN 31 STATES AFFECTING 160
MILLION PEOPLE FAILS TO MEET THE
FEDERAL HEALTH STANDARDS FOR
SMOG
• FOR DECADES THE CLEAN AIR ACT
HELPED IMPROVE THE AIR QUALITY
• 400 COAL-FIRED POWER PLANTS
PROVIDING 50% OF THE ELECTRICITY
WE USE ARE DIRTY OLD DINOSAURS
AND THE MAJOR SOURCE OF AIR
POLLUTION
• BURNING COAL RELEASES AIR
POLLUTANTS LIKE NITROGEN DIOXIDE
(FOUND IN SMOG), SULFUR DIOXIDE (FORMS
ACID RAIN), CARBON DIOXIDE WHICH
CONTRIBUTES TO GLOBAL WARMING AND
TOXIC MERCURY WHICH ENTERS OUR DIET
THROUGH THE FISH WE EAT AND HAS BEEN
LINKED TO BRAIN DAMAGE IN CHILDREN
AND FETUSES
• PLANTS BUILT IN THE 1950s ARE STILL
EMITTING AIR POLLUTION AT HIGH
LEVELS
• THE CLEAN AIR ACT STATES THAT IF
A UTILITY PLANT UPGRADES TO KEEP
AN AGING PLANT UP AND RUNNING, IT
MUST ADD MODERN AND EXPENSIVE
POLLUTION CONTROLS AS WELL
• ROUTINE MAINTENANCE, NO
PROBLEM
• BUT MAJOR CHANGES WITHOUT
POLLUTION CONTROLS IS AGAINST
THE LAW
• RECENT CHANGES IN THE
ENFORCEMENT OF THE CLEAN AIR
ACT BY THE FEDERAL
ADMINISTRATION ARE NOW
ALLOWING MAJOR CHANGES
WITHOUT ADDING POLLUTION
CONTROLS
• IT’S AS IF YOU HAD A 1950 CAR AND
YOU REPLACED THE TRANSMISSION
AND THE ENGINE WITHOUT PUTTING
ON CATALYTIC CONVERTERS
• THIS VIDEO SEGEMENT PRESENTS THE TWO
SIDES OF THE COIN:
• COMPLETION OF MAJOR UPGRADES WITH
MODERN AND EXPENSIVE POLLUTION
CONTROLS COSTING NEARLY A BILLION
DOLLARS BY A TAMPA UTILITY PLANT
TURNS OUT TO BE COST EFFECTIVE
• DECREASED ENFORCEMENT OF THE CLEAN
AIR ACT UNDER THE CURRENT FEDERAL
ADMINISTRATION LEADS TO INCREASED
RELEASE OF TOXIC POLLUTANTS BY COAL
BURNING UTILITY PLANTS
• THOUGHTS OR CONCERNS ON THE ISSUE?
WELL THAT ABOUT WINDS
UP TONIGHT’S
PRESENTATION FROM SAN
JOSE SATE WHERE THE
WOMEN ARE STRONG, THE
MEN ARE GOOD LOOKING,
AND ALL THE PROFESSORS
ARE LONG WINDED!