Transcript Aging - Institute of Energy and Sustainable Development

IESD PhD Conference: Energy
and Sustainable Development
Towards thermal comfort prediction for
the older population: a review of aging
effect on the human body
Divine T. Novieto, Dr. Yi Zhang
21st May 2010
Institute of Energy and Sustainable Development
Presentation Outline
• Information on Aging
• Aging effect on the body
• IESD-Fiala thermoregulation model
• Insight into the New Model
• Simulation and Results
Institute of Energy and Sustainable Development
Aging
• Is the detrimental changes with time that underlie an
increasing vulnerability to challenges thereby decreasing
the ability of the organism to survive.
• Also referred to as the progressive accumulation of
changes with time that are associated with the everincreasing susceptibility to disease and death which
accompanies advancing age.
• Most developed countries have accepted the
chronological age of 65 years as a definition of 'elderly' or
Old person.
Institute of Energy and Sustainable Development
Some Theories of Aging
• Wear-and-tear -Normal
wear and tear causes cells
to function improperly
• Cellular- Cells replicate a
specific number of times and
then die.
• Nutritional Model TheoryAnimals fed 50-60% less
than it eats on its own lives
longer
Ref [1]
Ref [2]
Assumption: Lean mass, as opposed
to adipose tissue results in greater health
Institute of Energy and Sustainable Development
The Aging Situation
Aging of populations around the world
with nearly 20% gain from age 65. By
2020 one fourth of the population in
many nations around the world will be
over 601. Fig 1 the Europe situation.
30%
65+
25%
80+
20%
15%
10%
5%
0%
2010
2020
2030
2040
2050
Ref [3]
As we age, we experience changes in
our solid organs and body functions,
these changes lead to diminished
physiological reserve resulting in the
inability of the body to maintain thermal
comfort in times of challenge
(hypothermia & hyperthermia)
Ref [4]
Institute of Energy and Sustainable Development
Age Concern
• In the 2003 heat wave, more than 2000 deaths were attributed
to the August heat wave in England & Wales. Excess mortality
was 33% in those aged 75+ and 13.5% in the under 75 age
group during the 10 day heat wave.
• Deaths at home increased by 33% among those aged 75+, and
deaths in Nursing homes increased by 42%. Around one
quarter of the heat wave attributable deaths occurred in care
homes.
• In France excess mortality was estimated at 20% for those aged
45-74 years, at 70% for the 75-94 year age group, and at 120%
for people over 94 years.
Institute of Energy and Sustainable Development
Effects of Aging on the Body
Institute of Energy and Sustainable Development
Effects of Aging on the Body
• Skin:Loss of subcutaneous fat, thinning
of skin, decreased collagen, less
sweat glands and difficulty in
regulation of temperature.
• Musculoskeletal system:Adipose tissue increases and
lean body mass decreases,
bone mineral content decreases,
decrease in height from narrow
vertebral spaces and increased
arthritis.
Ref [5]
Institute of Energy and Sustainable Development
Effects of Aging on the Body
• Heart:Limits of heart exertion reduced
with age, Heart less able to
pump efficiently, Blood vessels
lose elasticity with age making
heart have to pump harder to
circulate blood
• Central Nervous system:Neurons of central and peripheral
nervous system degenerate,
Nerve
transmission
slows
(slower reflexes), hypothalamus
less effective in regulating body
temperature.
Institute of Energy and Sustainable Development
Ref [6]
The aging impact diagram
•
The inter-relationship between the various components of the
body including muscle, heart, central nervous system, skin
and the effect aging as a natural phenomenon have on them.
CHANGED
THERMOREGULATION
REDUCED
VASODILATION
REDUCED
SWEATING
ABILITY
REDUCED
SHIVERING
POTENTIAL
REDUCED
VASOCONSTRICTION
AGEING EFFECT
CENTRAL
NEVOUS
SYSTEM
REDUCED
NEURAL
RESPONSES
MUSCLE
LOSS OF ACTIVE
MUSCLE MASS
HEART
REDUCED
HEART OUTPUT
VEINS &
ARTERIES
ARTERIES &
VEINS
STIFFNESS
SKIN
Institute of Energy and Sustainable Development
FRAGILE &
LESS ELASTIC
SEDIMENTARY
LIFESTYLE
REDUCED
METABOLIC
RATE
REDUCED BLOOD
PERFUSION
REDUCED MEAN
ARTERIES
PRESSURE
REDUCED SKIN
SENSITIVITY
The IESD-Fiala Model
IESD-Fiala model form the basis of this research and profiles the
human body as two interacting systems, i.e. the controlled passive
system (body structure) and the controlling active system (the
thermoregulatory functions). The passive system diagram below is
the focus of this paper.
19 spherical and
cylindrical elements
Institute of Energy and Sustainable Development
Revised model parameters
Typical person
(Fiala model)
87
Typical old person
(75yrs)
70
4.73
4.05
Body Weight (kg)
73.3
66
-10%
Height (m)
Body Surface Area
(m2)
1.72
1.66
-3.5%
1.86
1.73
- 7%
Item
BMR (W)
Cardiac
(L/min)
Output
Change
-19.2%
-14.4%
Simulation scenario
•
A transient simulation was carried out using the original IESD-Fiala model
(FM) and the older person model (OP) to compare their dynamic responses
to changing thermal environments of:- hot, cold and hot i.e. (30-15-30)0C.
Relaxing for 90 min
in a pre-test
chamber at 240C dry
bulb (Ta)
90min
In test
chamber
Temp. 300C
In test chamber Temp. 150C
120min
60min
240min
330min
Institute of Energy and Sustainable Development
In test chamber
Temp. 300C
60min
Results
30
15
30
30
35
30
32.5
34
FM
OP
FM
OP
32
Skin Temp.(0C)
33
Skin Temp(0C)
15
33
32
31
30
31.5
31
30.5
30
29.5
29
29
28
28.5
27
0
0
60
120
Tim e(m in)
180
60
240
Hand (palm) temperature
30
15
120
180
240
Tim e(m in)
Feet temperature
30
30
36
15
30
35.6
35.4
FM
OP
35.2
FM
OP
35
Skin Temp(0C)
Skin Temp (0C)
35.5
35
34.5
34.8
34.6
34.4
34.2
34
34
33.8
33.6
33.4
33.5
0
60
120
Tim e(m in)
180
240
Lower arm temperature
Institute of Energy and Sustainable Development
0
60
120
Tim e(m in)
180
Lower leg temperature
240
Conclusion
• The results from the simulations suggest that under the
test conditions skin temperatures on the hand (palm),
foot, lower arm, and lower leg were lower in the older
person than in the average person.
• These findings are in line with earlier studies (Inbar,
2004):-that age related characteristics affect the overall
rate of heat gain as well as the mechanisms through
which this heat is dissipated.
• And (Anderson, 1996):- peripheral thermosensitivity
appears to be progressively attenuated with age
Institute of Energy and Sustainable Development
Finally
• The aim of this research is to develop a customized computer
model for predicting thermal comfort of Old persons. The model
is expected to predict old persons thermal responses (physical
and physiological) and enable designers to estimate their comfort
needs and reactions to diverse environmental conditions at the
design stage.
• Hopefully we shall move …..from…this….
• To ……..this..
Institute of Energy and Sustainable Development