CLINICAL BIOCHEMISTRY
Clinical laboratory diagnosis of kidney and urinary tract disorders
Nitrogen balance
Energy expediture and energy supply Oxygen metabolism in the body
Clinical laboratory diagnosis of liver and biliary tract disorders
Oxygen metabolism in the body
Normal respiration depends on the combination of
> ventilation
> gas exchange in the lungs
> oxygen binding to hemoglobin
> cardiac output
Composition of dry atmospheric air
78% nitrogen
21% oxygen
0,03% carbon dioxid
0,1% inert gases
Oxygen gradient	
	pO2 (kPa)
Inspired air	21,4
Arterial blood	13,4
Venous blood	5,3
Expired air	15,4
Atmospheric pressure	101,5
The airways are divided into two zones:
the conducting zone
trachea, bronchi, terminal bronchioles
the respiratory Zone (the structures in which gas exchange occurs)
respiratory bronchioles, alveolar ducts and alveoli
FiO2
Fraction of inspired oxygen
Atmospheric air 0,21 Arteficial ventilation usually...0,4 Pure oxygen 1,0
Dead space volume
> anatomic dead-space (conductinc system)
> alveolar-dead-space (nonperfused alveoli)
Perfusion
Perfusion is greater at the base of lungs than at the apex
(upper areas)
Ventilation
is the exchange of gases between ambient air and lungs
possible causes of hypoxia
atmospheric air
low oxygen parcial pressure
high altitude - high mountains, high flights of aircrafts consumed oxygen - fire in the closed space
hypoventilation
deppression of respiratory (breathing) center in brain (Morphine) weakness of breathing muscles (energy exhausted persons) pain during breathing (chest injury, pleuritis)
possible causes of hypoxia
diffusion across the alveolo-capillar membrane
pulmonary aedema fibrotic process
ventilation / perfusion ratio
alveolar ventilation is approximately 4 l/min.
cardiac output averages 5 l/min V/P ratio = 0,8
possible causes of hypoxia
hemoglobin
concentration of total hemoglobin
anemia
effective concentration of hemoglobin
oxyhemoglobin
karbonylhemoglobin methemoglobin
Oxygen dissociation curve
relation between pO2 and hemoglobin saturation
The position of the oxygen dissociation curve reflects the affinity of hemoglobin for oxygen.
	Affinity is reduced by:
	(shift to the right)
>	Increases in temperature
>	Decreases in pH
>	Increases in pCO2
>	Increases in the erythocyte 2,3-diphosphoglycerate
possible causes of hypoxia
Cardiac output
heart failure myocard infarction
Tissues perfusion
hypovolemia shock
centralization of circulation
Specimens for oxygen measurement
Arterial blood is the most suitable specimen for oxygen measur..
(arteria puncture is relative invasive)
Arterialised capillary blood from ear lobulus.
Blood drawing must be done anaerobically
Sfijto
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Hypoxia
lack of oxygen in the tissues Lactic acid - product of anaerobic metabolism
Energy expediture and energy suplly
Energy need differs - patient to patient,
disease to disease, hour to hour
Calculation of basic energy expediture
Harris-Benedict equations
high (cm) .... waight(kg).... age(years).... sex (M/F)
1°Cover37°C................ +10%
middle stress ................ +30%
severe stress...................+ 100 %
Indirect calorimetry
Strong relationship between energy expediture and
oxygen consumption
Investigation of oxygen consumption
diference between oxygen content in inspired a expired air
Indirect calorimetry
O2 [l/min] x 1440 x 4,83 x 4,18 = kJ
Energetic equivalent
[kcal/l consumed oxygen]
glucose........5,05 kcal
fat..............4,69 kcal
protein.........4,49 kcal