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NONINVASIVE MEASUREMENT OF BLOOD ACID-BASE (pH)
USING CONCENTRATIONS OF EXHALED GASES
A. S. Altaan
1
, O. Abdallah
1
, Mohammad T. Othman
2
, Nasser Musaab
3
and A. Bolz
1
1
Biomedical Engineering Institute, Karlsruhe Institute for Technology, Karlsruhe, Germany
2
Department of Physical Education, College of Basic Education, Mosul University, Mosul, Iraq
3
Department of Internal Medicine and Cardiovascular, Ibn Sina Teaching Hospital, Mosul, Iraq
Keywords: Exhaled Breath, Partial Pressure of Oxygen, Concentration of Carbon Dioxide, Non-invasive Blood Acid-
base (pH).
Abstract: An important property of blood is its degree of acidity and alkalinity which is referred to as acid-base
balance. The acidity or alkalinity of the blood is indicated on the pH scale. The blood pH has a serious
effect on all of the body’s systems and the body uses different mechanisms to control the blood’s acid-base
balance. Acid-base imbalances result primarily from metabolic or respiratory failures, both imbalances
cause changing in the normal range of CO2 in the blood. The concentrations of oxygen and carbon dioxide
from the exhaled breath were used to evaluate the pH of the blood. The results show the relation between
concentration of the exhaled CO2 and the blood acid-base pH; decreasing CO2 causes the blood to be
alkaline, while increasing CO2 leads the blood to become acidic.
1 INTRODUCTION
During exercise the muscles are working harder than
normal and, as a result, they require more energy
than normal. Since the ATP energy used by the
muscles is generated with the aid of oxygen, it
follows that an increase in exercise intensity will
result in an increase in muscular oxygen demands.
Therefore, increased exercise intensity ultimately
corresponds to an increased in the volume of the
consumed oxygen. As the muscles working harder
they release more CO2 this will affect the balance of
O2 and CO2 in the blood, this is the reason that
breathing gets progressively faster and deeper as
exercise intensity increases, the body is trying to
provide more oxygen to the working muscles and
release the resulting carbon dioxide so that they can
generate enough ATP energy to keep the athlete
moving. Homeostasis is the overall process of
maintaining stability of the body’s internal physical
and chemical systems. These processes involve rapid
correction of disturbances that may arise, as well as
instance by instance adjustments to prevent gross
disturbance from arising. A simple example is that if
the heart rate and the respiratory rate did not
increase during physical exertion, body chemistry
would be significantly altered by the resulting deficit
in oxygen and accumulation of carbon dioxide. The
amount of carbon dioxide in the blood has an
immediate and direct effect on the body’s acid-base
balance, a key aspect of the internal chemical state.
1.1 Effect of the O2 and CO2 on the pH
Hydrogen ion activity can significantly affect the
metabolic function of the cells. Bicarbonate ion
(HCO
3
) is the most important form of CO2, both
HCO
3
and H
+
are carriage by blood. CO2 combines
with water to form carbonic acid, and this
dissociates to HCO
3
and H
+
. The conversion of CO2
to H
+
and HCO
3
-
ions has tremendous implications
for acid–base physiology. Every day, resting
metabolism produces more than 15,000 mmol of
CO2, or 15,000 mmol/L of carbonic acid, and this
acid leaves the body through the lungs. By
comparison, the kidneys typically excrete only 100
mmol/L of acid per day. The ability to change blood
pCO2 levels rapidly by changing ventilation has a
powerful effect on blood pH, so acid–base balance
depends on the integrated function of respiratory and
renal systems. Regulation of hydrogen ion (H
+
)
balance is similar in some ways to the regulation of
other ions in the body. For instance, to achieve
264
S. Altaan A., Abdallah O., T. Othman M., Musaab N. and Bolz A..
NONINVASIVE MEASUREMENT OF BLOOD ACID-BASE (pH) USING CONCENTRATIONS OF EXHALED GASES.
DOI: 10.5220/0003789502640269
In Proceedings of the International Conference on Bio-inspired Systems and Signal Processing (BIOSIGNALS-2012), pages 264-269
ISBN: 978-989-8425-89-8
Copyright
c
2012 SCITEPRESS (Science and Technology Publications, Lda.)