Hypoxia

Hypoxia D.A. Asir John Samuel, BSc (Psy), MPT (Neuro Paed),

MAc, DYScEd, C/BLS, FAGE Lecturer, Alva’s college of Physiotherapy,

Moodbidri

Dr.Asir John Samuel (PT)

Hypoxia

• An abnormally reduced O2 supply to tissue

• A pathological condition in which the body as

a whole (generalized hypoxia) or a region of

the body (regional hypoxia) is deprived of

adequate oxygen supply


Causes of Hypoxia

• Inadequate oxygenation

- Deficiency of oxygen in atmosphere

- Hypoventilation (neuromuscular disorders)

• Venous-to-arterial shunts (right-left cardiac

shunts)

- Eisenmenger's syndrome Dr.Asir John Samuel (PT)

Causes of Hypoxia

• Pulmonary disease

- Hypoventilation due to increased airway

resistance or decreased compliance

- Abnormal VA/Q ratio

- Diminished respiratory membrane diffusion


Causes of Hypoxia

• Inadequate oxygen transport to tissues

- Anaemia or abnormal Hb

- General circulatory deficiency

- Localized circulatory deficiency

- Tissue oedema


Causes of Hypoxia

• Inadequate tissue capability of using oxygen

- Poisoning of cellular oxidation enzymes

- Diminished cellular metabolic capacity for

using oxygen, because of toxicity, vitamin

deficiency or other factors


Effects of Hypoxia on body

• Hypoxia, if severe

- can cause death of cells throughout the body

• In less severe degrees

- Depressed mental activity, sometimes results

in coma

- Reduced work capacity of muscles


Types of Hypoxia

• Atmospheric Hypoxia (Hypoxic Hypoxia)

• Hypoventilation Hypoxia

• Anemic Hypoxia

• Stagnant or ischemic Hypoxia

• Histotoxic or cytotoxic Hypoxia


Atmospheric Hypoxia (Hypoxic Hypoxia)

• An insufficient O2 supply reaches the blood

• Due to

- Decreased atmospheric PO2 at high altitudes

- Reduced alveolar ventilation

- Impaired alveolar gas exchange


Hypoventilation Hypoxia

• A reduced amount of air enters the alveoli in

your lungs, resulting in hypoxia and hypercapnia

• COPD

• Scoliosis, nasal septum deformation

• Weakened respiratory muscles - motor neurone

disease


Anemic Hypoxia

• Reduced O2-carrying capacity of blood

• Due to decreased total Hb or RBC


Stagnant or ischemic Hypoxia

• Insufficient O2 reaches the tissue due to

reduced blood flow

• Systemic or local


Histotoxic or cytotoxic Hypoxia

• Impaired utilization of O2 by the tissues

despite a sufficient supply of O2 in the

mitochondria

• Cyanide poisoning

• Cyanide (HCN) blocks oxidative cellular

metabolism by inhibiting cytochromoxidase


Hyper Baric Oxygen Therapy (HBOT)

• Medical use of oxygen at a level higher than

atmospheric pressure

• Hyperbaric oxygen therapy involves breathing

pure oxygen in a pressurized room/chamber

• Raised upto 5 times

• 100% O2 is given


HBOT – indications • Atherosclerosis

• Stroke

• Peripheral vascular disease

• Diabetic ulcers

• Wound healing

• Cerebral palsy

• Brain injury

• Multiple sclerosis

• Many other disorders. Dr.Asir John Samuel (PT)

Hypercapnoea

• Excess carbon dioxide (CO2) in the body (> 45

mm Hg in blood)

• Associated with hypoxia

- Hypoventilation

- Circulatory deficiency

• Hypoxia caused by reduced availability of O2 Dr.Asir John Samuel (PT)

Hypercapnoea – Symptoms & signs • Flushed skin

• Full pulse

• Tachypnea

• Dyspnea

• Muscle twitches

• Hand flaps

• Reduced neural activity

• Raised blood pressure Dr.Asir John Samuel (PT)

Raised PCO2

• 60 to 75 mm Hg – air hunger (rapidly & deeply)

- Dyspnea

• 80 to 100 mm Hg – lethargic & semicomatose

• 120 to 150 mm Hg – anesthesia and death


Dysbarism

• Decompression sickness

• Nitrogen dissolved in

body develops nitrogen

bubbles and cause minor

or serious damage


Decompression sickenss

• Caisson’s disease


Dysbarism -symptoms

• Blocks many blood vessels in different tissues

• At first smallest vessels then larger vessels

• Tissue ischaemia and tissue death

• Pain in joints, muscles of leg or arms

• Dizziness or collapse and unconsciousness

• Shortness of breath, pulmonary edema Dr.Asir John Samuel (PT)

Acclimatization

• Acclimatization or acclimation is the process

of an individual organism adjusting to a

gradual change in its environment such as

pressure, temperature, etc


Acclimatization

• Decrease in barometric pressure is the basic

cause of all hypoxia problems in high-altitude

physiology

• As barometric pressure decreases, the

atmospheric oxygen partial pressure decreases

proportionately


Effects of Acclimatization

• Drowsiness

• Lassitude

• Mental and muscle fatigue

• Headache

• Nausea

• Twitchings or seizures Dr.Asir John Samuel (PT)

Effects of Acclimatization

• Decreased mental proficiency

• Decreases judgment

• Memory

• Performance of discrete motor movements


Hypoxia

Health & Medicine

asir john samuel pt

body hypoxia

hypoxia hypoventilation

effects of hypoxia

hypoxia problems

generalized hypoxia

cytotoxic hypoxia dr

circulatory deficiency