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When is adaptation complete
on ascent to high altitude ?
Gustavo Zubieta-Calleja (Jr)
Gustavo Zubieta-Castillo
High Altitude Pathology Institute
Clinica IPPA
La Paz – Bolivia
www.altitudeclinic.com
The definition of adaptation to high altitude
“The organic systems of human beings and all other
species tend to adapt to any environmental change
and circumstance, and never tend towards regression
which would inevitably lead to death”.
Gustavo Zubieta-Castillo Sr.
The High Altitude Adaptation Formula
Adaptation to high altitude =
time
altitude
For a fixed altitude, the only significant variable is time.
How long does it take to achieve full adaptation to a fixed altitude ?
The Mechanisms of Adaptation
to high altitude
• Macro-systemic
– Respiratory
• Increased Ventilation
– Cardiac
• Increased Heart Rate
• Pulmonary
Hypertension
• Micro-systemic
– Blood oxygen transport
• Hematocrit increase
• Increased circulation
– Neoangiogenesis
– Cellular changes
• Increased mitochondrial
density
• Sodium and Potassium
pump changes
• Hydro-balance
• Neuro-endocrine changes
• pH correction
The Mechanisms of Adaptation to high altitude
Hypoxia induced gene expression
Transcription factors
• Hypoxia inducible
factor-1
(HIF-1)
• Activator protein-1
(AP-1)
• Nuclear factor-IL6
(NF-IL6)
• Early growth factor
(Egf-1)
• Nuclear factor kappa B
(NFkB)
Relevant target genes
• Erythropoyetin
• Vascular endothelial
growth factor (VEGF)
• Tyrosine hydroxylase
• Endothelin 1
• Genes involved in
glucose metabolism
• Nitric Oxide synthase
OXYGEN TRANSPORT MECHANISMS
.
V
RR
VT
RESP. RATE
TIDAL VOL.
Hb
VS
HR
HEART RATE
.
Q
STROKE VOL.
Hematocrit increase
on return from sea level to high altitude 3510 m
Acute
Adaptation
70
65
Intermediate Adaptation
Full
Adaptation
Subacute Mountain Sickness
CMS
Ht in %
60
55
50
45
40
y = 3.8306Ln(x) + 36.141
R2 = 0.9929
35
30
0
10
20
30
Days
40
50
Conclusions
Immediate adaptation to high altitude is possible but is not
optimal nor definitive.
The optimal adaptation is achieved only when the hematocrit
reaches the plateau value.
This value is specific for each altitude and for each individual.
The time lapse depends on the initial hematocrit upon ascent
and on the health status.