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Getting High. John P. Hunt LSU New Orleans Department of Surgery. Which person could have this blood gas? 7.65/14/35/15/71%. Scuba diver on his third 100 ft dive of the day A marathon runner during a race A mountain climber at 22,000 ft A COPD patient in respiratory distress.

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Getting high

Getting High

John P. Hunt

LSU New Orleans

Department of Surgery


Which person could have this blood gas 7 65 14 35 15 71
Which person could have this blood gas?7.65/14/35/15/71%

  • Scuba diver on his third 100 ft dive of the day

  • A marathon runner during a race

  • A mountain climber at 22,000 ft

  • A COPD patient in respiratory distress

American Board of Surgery, written exam, 1995


Oxygen delivery from start to finish changes at altitude as a model

Oxygen Delivery –From Start to Finish: Changes at Altitude as a Model

John P. Hunt

LSU New Orleans

Department of Surgery


Objectives
Objectives as a Model

  • Historical Perspectives

  • Environmental and physiological changes

  • Symptoms

  • Effects on DO2

  • Prevention

  • Therapy


Where it s high
Where it’s High as a Model


Historical perspectives
Historical Perspectives as a Model

  • “Men’s bodies become feverish, they lose color and are attacked with headache and vomiting; the asses and cattle being in the same condition”

    Qian Han Shu, 30 BC


Historical perspectives1
Historical Perspectives as a Model

  • “I was quite out of breathe from the rarity of the air”

    DeSaussure 1787

  • “I feel funny and I don’t know why, excuse me while I kiss the sky”

    Hendrix 1969


Historical perspectives2
Historical Perspectives as a Model

  • “After we huddle over our ice axes, mouths agape, struggling for sufficient breath… I feel I no longer belong to myself and my eyesight. I am nothing more then a single narrow gasping lung”

    Messner 1978


Incidence
Incidence as a Model

  • 67% of mountaineers ascending Mount Rainier (14,405 ft)

  • 53 % of trekkers in the Himalayas (13,900 ft)

  • 12% of Colorado

    skiers (8,000 ft)


High altitude cerebral edema hace
High Altitude Cerebral Edema (HACE) as a Model

  • Less than 1% of all Mountain sickness

  • Always above 12,000 Ft

  • Symptoms: Severe headache, Ataxia, Loss of co-ordination, Diplopia, Confusion, Hallucinations, Death


Acute mountain sickness ams
Acute Mountain Sickness (AMS) as a Model

  • Usually above 10,000 Ft

  • Onset is 4-6 hours after exposure & Duration 3 Days

  • Symptoms: Headache, Insomnia, Irritability, Fatique, Nausea/vomiting


High altitude pulmonary edema hape
High Altitude Pulmonary Edema (HAPE) as a Model

  • Rarely below 8,000 Ft

  • Onset is 1-3 days after exposure

  • Symptoms: Dyspnea at rest, Pink frothy sputum, Rales, Cyanosis, mild temperature


Temperature at altitude
Temperature at Altitude as a Model

Temperature (F)

Altitude (ft)


Oxygen availability at altitude
Oxygen Availability at Altitude as a Model

Partial Pressure of O2 (mm torr)

Altitude (meters)


Oxygen delivery
Oxygen Delivery as a Model

DO2= C.O. x 10 x

[(Hgb x SaO2 x 1.34) + (PO2 x 0.0031)]


Oxygen delivery may be calculated as a function of
Oxygen Delivery may be calculated as a function of? as a Model

  • C.O., O2 saturation, mvO2 saturation

  • C.O., mvO2 extraction, mvO2 saturation

  • C.O., mvO2 saturation, Hgb

  • C.O., Hgb, O2 saturation

  • Difference between mvO2 saturation O2 saturation and C.O.


Acute hypoxia produces
Acute Hypoxia Produces? as a Model

  • Increased pulmonary vascular resistance

  • Increased pulmonary blood flow

  • Increased total blood volume

  • Decreased epinephrine

  • Increased splanchnic perfusion


Comparative oxygen tension
Comparative Oxygen Tension as a Model

Ventilation

Sea Level

Partial Pressure O2

Altitude

Level


How does ventilation improve oxygenation
How does Ventilation Improve Oxygenation? as a Model

  • Classic Ventilator Management dictates

    -M.V. – PCO2

    -FiO2 – PO2


Alveolar gas equation
Alveolar Gas Equation as a Model

PAO2= (PB – PH2O)FIO2– PaCO2/RQ


Comparative oxygen tension1
Comparative Oxygen Tension as a Model

V/Q Mismatch

Sea Level

Partial Pressure O2

Altitude

Level


V q mismatch
V/Q Mismatch as a Model

  • Dead space

  • Shunt

  • Diffusion


Calculation of shunt
Calculation of Shunt as a Model

QS/QT= (CC02 – Ca02)/(CC02 – Cv02)

  • Understand the concept


Lung volumes
Lung Volumes as a Model

  • Pursed-lips technique


V q mismatch and diffusion
V/Q Mismatch and Diffusion as a Model

Diffusion

% Total A-a P O2

V/Q Mismatch

Altitude (M)

Wagner PD et al J Appl Physiol 1987;63:2348


3 days following operation for a perforated ulcer a 68 y.o man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

  • Increase minute ventilation

  • Decrease minute ventilation

  • Increase functional residual capacity

  • Increase compliance

  • Decrease the I:E ratio


The primary mechanism by which peep improves oxygenation is
The primary mechanism by which PEEP improves oxygenation is? man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

  • Decreased air-flow resistance

  • Increased functional residual capacity

  • Increased forced vital capacity

  • Decreased interstitial lung water

  • Decreased ratio of dead space to total volume


Comparative oxygen tension2
Comparative Oxygen Tension man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

Circulation & Extraction

Sea Level

Partial Pressure O2

Altitude

Level


Hemoglobin
Hemoglobin man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

  • 33% Increase in Hgb

  • Secondary to significant increases in erythropoetin

  • Chronic exposure typically yields Hct in the 60 range


Cardiac output
Cardiac Output man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

  • Preload

  • Contractility

  • Afterload


Cardiac output1
Cardiac Output man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

  • Increase in SV

  • No changes in afterload

  • Preload sensitive DO2


Starling mechanism
Starling Mechanism man requires intubation. Initial ABG on 100% shows 7.32/72/36. To improve oxygenation the ventilator should be adjusted to?

  • Dehydration and subsequent decrease in preload is the mountaineers worst enemy

  • 80% of carried fuel is used to make water

Cardiac Output

EDV


Starlings law states that cardiac contractility increases when
Starlings Law states that cardiac contractility increases when?

  • SVR Increases

  • SV Increases

  • LVSW Decreases

  • EDV Increases

  • SV Increases and SVR Increases


Hemoglobin oxygen dissociation
Hemoglobin-Oxygen Dissociation when?

  • Shifting the curve to the right decreases the affinity of hemoglobin for oxygen inducing off-loading

    -Increased temp

    -Decreased pH

    -Increased CO2

    -Increased 2-3 DPG

O2 Sat

PaO2


A shift in the oxygen hemoglobin dissociation curve to the right is characteristic of
A Shift in the Oxygen-Hemoglobin-Dissociation curve to the right is characteristic of?

  • Hyperventilation

  • Increased carboxy-hemoglobin

  • Decreased affinity of hemoglobin for oxygen

  • Decreased A-V O2 difference

  • May be caused by hypothermia


Extraction ratio
Extraction Ratio right is characteristic of?

  • VO2/DO2

  • VO2 = Q x (Ca02 – Cv02)

    = Q x 1.34 x Hgb (Sa02 – MV02)

  • Mountaineers have a maximized extraction ratio


At rest mvo 2 saturation
At rest MvO right is characteristic of?2 Saturation?

  • Normally ranges between .48-.55

  • Increases as O2 consumption increases

  • Increases as Hgb decreases

  • Increases as Cardiac Output increases

  • Decreases as Arterial oxygen saturation increases


Therapy
Therapy right is characteristic of?

  • Descend

  • Bedrest

  • Supplemental oxygen

  • Gamow Bag


Prevention
Prevention right is characteristic of?

  • Slow ascent

  • Climb high, sleep low

  • Acetazolamide

  • Nifedipine


Nifedipine for hape
Nifedipine For HAPE right is characteristic of?

  • 21 volunteers with previous history of HAPE

  • Ascended to 4559 M

  • Nifedipine vs Placebo

  • Pulmonary edema in 1 in 10 of treated group vs 7 of 11 in control group

  • Reproduced by Oelz O. et al

Bartsch P. et al NEJM 1996;325:1284


Acetazolamide for ams
Acetazolamide For AMS right is characteristic of?

  • 64 healthy volunteers ascending Mount Rainier

  • 93.6% of treatment group and 75.8% of controls reached the summit

  • 66.7% of controls and 17.2% of the treatment group developed AMS

  • Reproduced by Grissom et al on Denali

Larson EB. et al JAMA 1982;248:329


Summary
Summary right is characteristic of?

  • Mountain Climbers optimize O2 delivery by

    -A four-fold increase in ventilation

    -Optimizing V/Q matching

    -Increasing Hgb via erythropoesis

    -Optimizing the O2 Extraction Ratio


Summary1
Summary right is characteristic of?

  • HACE, HAPE, AMS are different forms of Altitude sickness

  • Judicious climbing practices and medical prophylaxis are warranted

  • Descent is the best therapy for altitude sickness


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