Applied Physiology

1. Dyspnea, Hypoxia, Cyanosis,
Asphyxia, Drowning and
Periodic breathing
Dr. Sai Sailesh Kumar G
Associate Professor
Department of Physiology
RDGMC

2. Dyspnea
 Mental anguish associated with inability to ventilate
enough to satisfy the demand for air ( difficulty in
breathing)
 Air hunger ( occurs both in physiological and pathological
conditions)
 Three major causes
1. Hypercapnia (mainly) and hypoxia ( to some extent)
2. Increased Work of breathing (exercise / Lung diseases)
3. State of mind

3. Dyspnea
 Individual develops dyspnea when excess of CO2
accumulates in body fluids (difficult breathing)
 When a person breath forcefully, the forceful activity of
respiratory muscles gives the person a sensation of
dyspnea
 Dyspnea due to abnormal state of mind – emotional
dyspnea or neurogenic dyspnea
 This is more common in people who has psychological
fear of not being able to receive adequate quantity of air
such as entering small or crowded rooms

4. Dyspneic index (DI)
 Breathing reserve/ MVV x 100
 MVV= maximum voluntary ventilation – 110 lit/min
 Breathing reserve for a person breathing 5 lit/ min is
110-5 = 105 l/min
 105/110 x100 = 95.45
 When DI becomes 60 or below, then dyspnea starts

5. Hypoxia
 Insufficient oxygen supply to the tissues
 Hypoxia and hypoxemia are different
 Classified into four classes
1. Hypoxic Hypoxia
2. Stagnant Hypoxia
3. Anemic Hypoxia
4. Histotoxic Hypoxia

6. Hypoxic Hypoxia
 Occurs when PO2 of arterial blood decreases
 Low barometric pressure
 Diseases like
1. Gas exchange failure in the lungs
2. emphysema
3. Asthma
4. Pneumothorax

7. Hypoxic Hypoxia
 Low barometric pressure occurs at high altitudes
 Acute Mountain Sickness
 Soldiers, who flown high up from low areas due to
urgency (a hazard faced repeatedly by Indian
Soldiers)
 When pressurized cabin of aero plane become faulty

8. Hypoxic Hypoxia
 Atmospheric PO2 decreases
 Alveolar PO2 decreases
 RBC count normal
 Blood flow is normal
 Tissue utilization of oxygen is normal

9. Anemic Hypoxia
 Decrease in the RBC
 Decrease in Hemoglobin
 Decrease in the oxygen carrying capacity
 Also seen in CO poisoning
 CO has 250 times more affinity for hemoglobin than
oxygen
 COHB will be formed and that prevents uptake of
oxygen (decreased oxygen carrying capacity)

10. Anemic Hypoxia
 CO poisoning causes shift of oxygen dissociation curve
to left
 CO poisoning causes hypoxia of brain – leads to head
ache
 CO is present in coal gas
 Also seen in CO poisoning and auto mobile exhaust
fumes ( professional drivers suffer with chronic and mild
CO poisoning)
 CO poisoning can be managed by hyperbaric oxygen
therapy

11. Anemic Hypoxia
 Atmospheric PO2 normal
 Alveolar PO2 normal
 RBC count decreased
 Blood flow is normal
 Tissue utilization of oxygen is normal

12. Stagnant Hypoxia
 Circulation becomes very sluggish
 Blood stays in the capillaries for too long period
 Tissues continue to draw oxygen from capillaries
 Capillary blood becomes deficient in oxygen
 Occurs in Cardio vascular shock and CHF
(congestive heart failure)

13. Stagnant Hypoxia
 Atmospheric PO2 normal
 Alveolar PO2 normal
 RBC count normal
 Blood flow is decreased
 Tissue utilization of oxygen is normal

14. Histotoxic Hypoxia
 Inhibition of cytochrome oxidase
 Occurs due to cyanide poisoning
 Cytochrome oxidase is a key enzyme for tissue
oxidation
 Tissue oxidation is inhibited
 Tissues can not extract oxygen from capillaries
 PO2 of arterial and venous blood will be same

15. Histotoxic Hypoxia
 Atmospheric PO2 normal
 Alveolar PO2 normal
 RBC count normal
 Blood flow is normal
 Tissues can not use oxygen

16. Oxygen therapy
 Provided to patients with hypoxia
1. Placing the patient’s head in a tent that contained
air
2. Providing the patient either pure oxygen or high
concentration of oxygen to breath from a mask
3. Administering oxygen through intra nasal tube

17. Hyperbaric Oxygen therapy
 Oxygen supply at high pressures
 Patients were placed in a large pressure tanks and
treated with hyperbaric oxygen
 The oxygen is administered at PO2 values 2-3
atmospheric pressure through a mask or intra tracheal
tube
 Used in the treatment of gas gangrene infections.
Clostridial organisms grows best under anaerobic
conditions and stop growing when pressure of oxygen
increases

18. Hyperbaric Oxygen therapy
 Used in the treatment of
1. Decompression sickness
2. Arterial gas embolism
3. Carbon monoxide poisoning
4. Osteomyelitis
5. Myocardial infarction

19. Where Cyanosis is seen?
 Bluish discoloration of skin and mucous membrane
 Increase in the concentration of reduced hemoglobin >5
grams / 100 ml of blood
 It is commonly seen in (where PO2 is very low)
1. Mountain sickness
2. Cyanotic heart disease
3. COPD
4. Pulmonary edema
5. Circulatory shock

20. Where Cyanosis is not seen?
 When the concentration of reduced hemoglobin <5
grams / 100 ml of blood
 Cyanosis not seen in
1. Anemic hypoxia
2. Histotoxic hypoxia
3. CO poisoning (CO-Hb is in cherry red color)

21. Why cyanosis absent in anemic hypoxia?
 Hemoglobin concentration in the blood is less than 5
grams/100 ml of blood in severe anemia

22. Why cyanosis absent in histotoxic
hypoxia?
 HbO2 can not be converted into reduced hemoglobin

23. Asphyxia
 Means both hypoxia and CO2 retention (hyper-
capnia) is present
 Acute asphyxia kills the patient within few minutes
 It is seen in
1. Strangulation
2. Acute upper respiratory tract obstruction
3. Drowning
4. Circulatory shock

24. Drowning
 Impairment of respiration from immersion (only head
in water)/ submersion (head and body under water)
in liquid
 It is a form of asphyxia
 Classified two types according to type of water
1. Fresh water drowning – Lakes, pools, rivers
2. Sea water drowning - sea

25. Drowning

26. Drowning
 Individual becomes panic
 Loss of normal breathing pattern
 He do not want to suck water so he holds breath
 Air hunger increases (desire to breath increases)
 Aspiration of water
 Reflex laryngeal spasm (to limit aspiration)
 Hypoxemia
 With in first few minutes

27. Salt water Drowning
 Aspiration of salt water
 Salt water in alveoli
 More electrolytes in alveoli
 Less electrolytes in capillary
 Movement of water from capillaries to alveoli
 Pulmonary edema

28. fresh water Drowning
 Aspiration of fresh water
 Fresh water in alveoli
 Less electrolytes in alveoli
 More electrolytes in capillary
 Movement of water from alveoli to capillaries
 Hemodilution

29. Dirty water Drowning
 Aspiration of Dirty water
 Dirty water in alveoli
 Aspiration of bacteria
 Diseases like pneumonia may occurs

30. Aspiration in Drowning
 Aspiration of water is less important
 One can aspire 3-4 ml/kg
 Because of reflex laryngeal spasm
 So most of the water goes to stomach

31. Pulmonary effects of Drowning
 Washing out of surfactant
 Collapse of alveoli
 V/P mismatch
 No oxygenation of blood
 hypoxemia
 Hemodilution

32. Neurological effects of Drowning
 hypoxemia
 Cerebral edema
 Increase in intra cranial pressure
 Ischemia of brain
 Neuronal damage

33. Cardiovascular and renal effects of
Drowning
 Arrhythmias – Fibrillation of atria
 Hemoglobinuria
 Myoglobinuria

34. Pre-hospital management
 Initiate CPR
 Maintain ventilation
 Supplements of oxygen
 Intubation if necessary

35. Emergency room
 A- Airway (intubation)
 B- Breathing (supplements of O2)
 C- Circulation ( monitor BP, Pulse Po2 etc.)
 D- Disability (Diuretics if Increased ICP)
 E- Exposure ( remove wet clothes and re warm)

36. Abnormalities in regulation of respiration
1. Respiratory center depression
 Old age
 Anesthetics
2. Periodic breathing:
It consists of alternate waxing and waning of
respiration or alternate hyper apnea and apnea.

37.  Types of Periodic breathing are:
a) Voluntary hyperventilation
b) Cheyne-Stokes respiration
c) Biot’s Breathing.

38. THANK YOU