Hypoxia

Rudyanto Sedono

ICU Department of Anesthesiology

Faculty of Medicine University of Indonesia

Cipto Mangunkusumo Hospital

Jakarta

Topic related

Hypoxia definition Oxygen transport Type of hypoxia

Hypoxia

Hypoxemia

Insufficient oxygen at the cellular level Inadequate cellular oxygen uptake and

utilizationReduce oxygen for tissue respirationOxygen tension at cellular level is

inadequate

Hypoxia

Hypoxemia

Decreased oxygen partial pressure in arterial

Relative deficiency of oxygen in the arterial blood

Decreased oxygen concentration in the arterial blood

Oxygen is important for maintain aerobic metabolism in cellular level

of the body

Oxygen transport

1. Convection

2. Diffusion

3. Chemical reaction

Oxygen transport from air to the cell

ALVEOLUS

Lung capillary

AIR :

PiO2 : 20.9 % x 760 = 159 mmHg

PiCO2 : 0.04 % x 760 = 0.3 mmHg

PiN2 : 78.6 % x 760 = 597mmHg

PiH2O : 0.46 % x 760 = 3.5 mmHgN2 H2O

O2

PAO2:104 mmHg

CO2

PACO2:40 mmHg

O2

PaO2: 40 mmHg

O2

PaO2: 104 mmHg

CO2PaCO2: 45 mmHg

CO2PaCO2: 40 mmHg

PAN2:573 mmHg

PAH2O:47 mmHg

Diffusionprocess

Convection process

Chemical reaction process of oxygen bound to haemoglobin

Rule of hemoglobin affinity to oxygen.Describe as oxygen dissociation curve

Fick :

DO2 ( ml/min ) = 10 x CO ( L/min ) x CaO2

CaO2 = 1.34 x Hb x SaO2 + 0.003 x PaO2

Normal DO2 ≈ 1000 ml/minCO ≈ 5 L/minHb = 15 gr/100ml

SaO2 100%

Convection process of oxygen from heart-lung to capillary level

Diffusion process of oxygen from capillary to cell

Hypoxia

1. Hypoxic hypoxia

2. Circulatory hypoxia

3. Anemic hypoxia

4. Cytophatic hypoxia

Hypoxic hypoxia

Blood flow to capillary is held constant but oxygen saturation is decreased

Refers to the steps that depend on diffusion of oxygen

Diffusion from the lungs into arterial blood Diffusion from oxygenated capillary blood into

the tissues Low PO2 is the hallmark of hypoxic hypoxia

Caused of hypoxic hypoxia

1. Diffusion limitation

2. Hypoventilation

3. Decreased Fraction Inspiration of Oxygen

4. Shunting

5. V / Q mismatch

6. Contribution of low Mixed Venous Oxygen Saturation

Circulatory Hypoxia

Blood flow into a capillary is decreased while the arterial PO2 remains constant

Depend on cardiovascular system Stimulating the peripheral chemoreceptor Tachycardia, bradycardia, peripheral

vasoconstriction or vasodilatation

Anemic Hypoxia

The arterial hemoglobin concentration ( hematocrit ) decreased Decreased oxygen delivery Perioperative period hematocrit 30% as

optimal

Physiologic response to anemic hypoxia

1. Cardiac output response to hemodilution

- Increased stroke volume

- Increased heart rate

- Decreased peripheral vascular resistance

2. Blood oxygen extraction ratio

- Systemic and microcirculatory level

Cytopathic Hypoxia

Impaired production of ATP despite adequate availability of O2 in the cell

Sepsis condition Impaired mitochondrial function in sepsis Increased expression of various

mitochondrial uncoupling proteins Mitochondrial permeability transition

If you are not

confused, you are not conscious

Thank you