1 Respiratory Patterns

Respiratory pattern is altered by many ways.

Altered Patterns of Respiration

Common altered patterns of respiration include:

2 Apnea

Definition

Apnea can also be produced voluntarily which is called breath holding or voluntary apnea.

Breath holding time is known as apnea time.

Breath-Holding Time in Normal Adult

About 45 to 55 seconds, after a deep inspiration.

Conditions When Apnea Occurs

1. Voluntary effort (voluntary breath holding or apnea).
2. After hyperventilation.
3. During deglutition (deglutition apnea).
4. During stimulation of vagus nerve in animals (vagal apnea).
5. After injection of adrenaline (adrenaline apnea).
6. During sleep (sleep apnea).

3 Hyperventilation

Definition

Causes of Hyperventilation

Hyperventilation mostly occurs in conditions like exercise when partial pressure of carbon dioxide is increased.

Excess of carbon dioxide stimulates the respiratory centers.

Voluntarily also, hyperventilation can be produced. It is called voluntary hyperventilation.

Effects of Hyperventilation

During hyperventilation, excessive carbon dioxide is washed out.

In blood, the partial pressure of carbon dioxide is reduced.

It causes suppression of respiratory centers resulting in apnea.

Apnea is followed by Cheyne-Stokes type of periodic breathing.

After a period of Cheyne-Stokes breathing, normal respiration is restored.

4 Hypoventilation

Definition

Thus, the amount of air moving in and out of lungs is reduced.

Causes of Hypoventilation

Hypoventilation occurs when respiratory centers are suppressed or by administration of some drugs.

It also occurs during partial paralysis of respiratory muscles.

Effects of Hypoventilation

Hypoventilation results in development of hypoxia along with hypercapnia.

It increases the rate and force of respiration, leading to dyspnea.

Severe conditions result in lethargy, coma and death.

5 Hypoxia

Definition

Causes of Hypoxia

Four important causes of hypoxia are:

1. Decreased oxygen tension in arterial blood.
2. Decreased oxygen carrying capacity of blood.
3. Decreased velocity of blood flow.
4. Decreased utilization of oxygen by the cells.

Classification of Hypoxia

Depending upon cause, hypoxia is classified into four types:

1. Hypoxic hypoxia.
2. Anemic hypoxia.
3. Stagnant hypoxia.
4. Histotoxic hypoxia.

Each type of hypoxia may be acute or chronic.

Simultaneously, two or more types of hypoxia may be present.

I. Hypoxic Hypoxia

Hypoxic hypoxia means decreased oxygen content in the blood. It is also called arterial hypoxia.

Causes for Hypoxic Hypoxia

1. Low oxygen tension in inspired atmospheric air.
2. Respiratory disorders.
3. Cardiac disorders.

Characteristic Features of Hypoxic Hypoxia

Hypoxic hypoxia is characterized by decreased oxygen tension in arterial blood.

All other features remain normal.

II. Anemic Hypoxia

Anemic hypoxia is a condition characterized by inability of blood to carry enough amount of oxygen.

The oxygen availability is normal, but the blood is not able to take up sufficient amount of oxygen due to anemic condition.

Causes of Anemic Hypoxia

Any condition that causes anemia can cause anemic hypoxia.

1. Decreased number of RBCs.
2. Decreased hemoglobin content in the blood.
3. Formation of altered hemoglobin.
4. Combination of hemoglobin with gases other than oxygen and carbon dioxide.

Characteristic Features of Anemic Hypoxia

Anemic hypoxia is characterized by the decreased oxygen carrying capacity of blood.

All other features remain normal.

III. Stagnant Hypoxia

It is the hypoxia caused by decreased velocity of blood flow.

It is otherwise called hypokinetic hypoxia.

Causes of Stagnant Hypoxia

Stagnant hypoxia occurs mainly due to reduction in velocity of blood flow.

1. Congestive cardiac failure.
2. Hemorrhage.
3. Vasospasm.
4. Thrombosis.
5. Embolism.

Characteristic Features of Stagnant Hypoxia

Characteristic feature of stagnant hypoxia is the decreased velocity of blood flow.

All other features remain normal.

IV. Histotoxic Hypoxia

Histotoxic hypoxia is a type of hypoxia produced by the inability of tissues to utilize oxygen.

Causes for Histotoxic Hypoxia

Histotoxic hypoxia occurs due to cyanide or sulfide poisoning.

Both the substances destroy cellular oxidative enzymes.

So, even if oxygen is supplied, the tissues are not able to utilize it.

Characteristic Features of Histotoxic Hypoxia

Histotoxic hypoxia is characterized by inability of tissues to utilize oxygen even if it is delivered.

All other features remain normal.

Characteristic Features of Different Types of Hypoxia

Effects of Hypoxia

Chronic hypoxia produces various symptoms in the body.

A. Immediate Effects of Hypoxia

B. Delayed Effects of Hypoxia

Delayed effects appear depending upon the length of exposure and severity of hypoxia.

The person becomes highly irritable and develops symptoms of mountain sickness, such as nausea, vomiting, depression, weakness and fatigue.

Treatment for Hypoxia: Oxygen Therapy

Best treatment for hypoxia is oxygen therapy, i.e. treating the person with oxygen.

Pure oxygen or oxygen combined with another gas is administered depending upon the situation.

Oxygen therapy can be given either under normal atmospheric pressure or under high pressure (hyperbaric oxygen).

Normal Atmospheric Pressure

At normal atmospheric pressure, i.e. at one atmosphere (760 mm Hg), administration of pure oxygen is tolerated by the patient for long hours.

High Atmospheric Pressure: Hyperbaric Oxygen

Hyperbaric oxygen is pure oxygen with high pressure of more than 2 atmospheres.

Hyperbaric oxygen therapy with 2 to 3 atmospheres is tolerated by the patient for about 5 hours.

But oxygen toxicity develops when pure oxygen is administered for long periods.

Efficacy of Oxygen Therapy in Different Types of Hypoxia

6 Oxygen Toxicity

Definition

Cause of Oxygen Toxicity

Oxygen toxicity is caused by breathing hyperbaric oxygen.

In this condition, excess amount of oxygen is transported in plasma as dissolved form because oxygen carrying capacity of hemoglobin is decreased.

Effects of Oxygen Toxicity

1. Lung tissues are affected first with tracheobronchial irritation and pulmonary edema.
2. Metabolic rate increases in all the body tissues and tissues are burnt out by excess heat. Heat also destroys cytochrome system leading to damage of tissues.
3. When brain is affected, first hyperirritability occurs, followed by increased muscular twitching, ringing in ears and dizziness.
4. Finally, toxicity results in convulsions, coma and death.

7 Hypercapnia

Definition

Causes of Hypercapnia

It occurs in conditions which lead to blockage of respiratory pathway as in case of asphyxia.

It also occurs while breathing air containing excess carbon dioxide content.

Effects of Hypercapnia

1. Excess stimulation of respiratory centers leading to dyspnea.
2. Reduction in pH of blood.
3. Increase in heart rate and blood pressure.
4. Headache, depression and laziness.
5. Muscular rigidity, tremors and convulsions.
6. Giddiness and loss of consciousness.

8 Hypocapnia

Definition

Conditions When Hypocapnia Occurs

It occurs in conditions associated with hypoventilation.

It also occurs after prolonged hyperventilation, because of washing out of excess carbon dioxide.

Effects of Hypocapnia

1. Rate and force of respiration decrease.
2. The pH of blood increases leading to respiratory alkalosis.
3. Tetany develops because of decreased calcium concentration.
4. Dizziness, mental confusion, muscular twitching and loss of consciousness.

9 Asphyxia

Definition

It is caused by hypoxia or hypercapnia due to obstruction of air passage.

Conditions When Asphyxia Occurs

Asphyxia develops in conditions characterized by acute obstruction of air passage such as:

• Hanging.
• Strangulation.
• Drowning.

Effects of Asphyxia

Effects of asphyxia develop in three stages.

1. Stage of Hyperpnea

It is the first stage of asphyxia.

It extends for about 1 minute.

In this stage, breathing becomes deep and rapid.

It is due to the powerful stimulation of respiratory centers by carbon dioxide accumulated.

Hyperpnea is followed by dyspnea and cyanosis.

The eyes become more prominent.

2. Stage of Convulsions

This stage is characterized by convulsions (uncontrolled involuntary muscular contractions).

Duration of this stage is less than one minute.

Following effects develop in this stage due to the effect of hypercapnia on brain:

1. Expiratory efforts become more violent.
2. Generalized convulsions appear.
3. Heart rate increases.
4. Arterial blood pressure increases.
5. Consciousness is lost.

3. Stage of Collapse

This stage lasts for about three minutes.

Severe hypoxia produces the following effects during this stage:

1. Depression of brain centers due to lack of oxygen. So, convulsions disappear.
2. Respiratory gasping occurs with stretching of the body and opening of mouth as if gasping for breath.
3. Dilatation of pupils.
4. Reduction in heart rate.
5. Loss of all reflexes.
6. Gradual increase in the duration between the gasps.
7. Finally, death.

Duration between the gasps is gradually increased and finally death occurs.

10 Dyspnea

Definition

Normally, breathing goes on without our consciousness.

When breathing enters the consciousness and produces discomfort, it is called dyspnea.

Dyspnea is also defined as “a consciousness of necessity for increased respiratory effort”.

Dyspnea Point

Dyspnea point is the level at which there is increased ventilation with severe breathing discomfort.

A normal person is not aware of any increase in breathing until pulmonary ventilation is doubled.

Real discomfort develops when ventilation increases by 4 or 5 times.

Conditions When Dyspnea Occurs

Physiological Condition

Physiologically, dyspnea occurs during severe muscular exercise.

Pathological Conditions

1. Respiratory disorders which involve obstruction in any part of respiratory tract.
2. Cardiac disorders such as left ventricular failure and mitral stenosis.
3. Metabolic disorders such as diabetic acidosis.

11 Periodic Breathing

Periodic breathing is of two types namely Cheyne-Stokes breathing and Biot breathing.

Cheyne-Stokes Breathing

Definition

It is the most common type of periodic breathing.

Features of Cheyne-Stokes Breathing

Cheyne-Stokes breathing is marked by two alternate patterns of respiration:

1. Hyperpneic period.
2. Apneic period.

1. Hyperpneic Period: Waxing and Waning of Breathing

To begin with, the breathing is shallow.

Force of respiration increases gradually and reaches the maximum (hyperpnea).

Then, it decreases gradually and reaches minimum.

Now it is followed by apnea.

The gradual increase followed by gradual decrease in force of respiration is called waxing and waning of breathing.

2. Apneic Period

When force of breathing is reduced to minimum, cessation of breathing occurs for a short period.

It is again followed by hyperpneic period and the cycle is repeated.

Causes for Waxing and Waning

Initially, during forced breathing, large quantity of carbon dioxide is washed out leading to inactivation of respiratory centers.

During apnea, there is accumulation of carbon dioxide with reduction in oxygen tension resulting in activation of respiratory centers.

This causes gradual increase in the force of breathing to the maximum.

And the cycle is repeated.

Conditions When Cheyne-Stokes Breathing Occurs

Physiological Conditions

1. During deep sleep.
2. In high altitude.
3. After prolonged voluntary hyperventilation.
4. In newborn babies.
5. After severe muscular exercise.

Pathological Conditions

1. During increased intracranial pressure.
2. During cardiac failure.
3. During renal diseases.
4. Poisoning by narcotics.
5. In premature infants.

Biot Breathing

Definition

Features of Biot Breathing

There is no waxing and waning of breathing.

After apneic period, hyperpnea occurs and the cycle is repeated.

Causes of Abrupt Apnea and Hyperpnea

Due to apnea, carbon dioxide accumulates and it stimulates the respiratory centers leading to hyperpnea.

During hyperpnea, lot of carbon dioxide is washed out.

So, the respiratory centers are not stimulated and apnea occurs.

Conditions When Biot’s Breathing Occurs

Biot’s breathing occurs only in pathological conditions such as nervous disorders involving lesions in respiratory centers.

12 Cyanosis

Definition

Cause for Cyanosis

Cyanosis is caused by the presence of large amount of reduced hemoglobin in blood.

Quantity of reduced hemoglobin should be at least 5 to 7 g/dL in the blood to cause cyanosis.

Distribution of Cyanosis

Cyanosis is distributed all over the body.

But it is more marked in certain regions such as lips, cheeks, ear lobes, nose and fingertips above the base of the nail.

Conditions When Cyanosis Occurs

1. Any condition which leads to arterial hypoxia and stagnant hypoxia.
2. Conditions when altered hemoglobin like methemoglobin or sulfhemoglobin is formed.
3. Conditions like polycythemia when blood flow is slow.

13 Respiratory Disorders

Carbon Monoxide Poisoning

Source of Carbon Monoxide

Common sources for carbon monoxide are:

• Exhaust of gasoline engines.
• Coal mines.
• Gases from guns.
• Deep wells.
• Underground drainage system.

Effects of Carbon Monoxide

Carbon monoxide is a dangerous gas because it displaces oxygen from hemoglobin by binding with the same site in hemoglobin for oxygen.

So, oxygen transport and oxygen carrying capacity of the blood are decreased.

Symptoms of Carbon Monoxide Poisoning

1. While breathing air with 1% of carbon monoxide, mild symptoms like headache and nausea appear.
2. While breathing air containing carbon monoxide above 1%, convulsions, cardiorespiratory arrest, loss of consciousness and coma occur.
3. High carbon monoxide content in air causes death.

Atelectasis

When a large portion of lung is collapsed, the partial pressure of oxygen is reduced in blood, leading to dyspnea and death.

Atelectasis is caused by deficiency of surfactant, obstruction of bronchus or bronchiole.

Causes of Atelectasis

1. Pneumothorax: Presence of air in pleural cavity.
2. Hydrothorax: Presence of fluid in pleural cavity. Hydrothorax is the synonym of pleural effusion.
3. Hemothorax: Presence of blood in pleural cavity.
4. Pyothorax: Presence of air pus pleural cavity.

Pneumothorax

Air enters the pleural cavity because of damage of chest wall or lungs during accident, bullet injury or stab injury.

Pneumonia

Affected part of the lungs becomes consolidated.

Inflammation of lung is caused by bacterial or viral infection and inhaling noxious chemical substance.

Features of Pneumonia

• Fever.
• Chest compression.
• Chest pain.
• Shallow breathing.
• Cyanosis.
• Insomnia (sleeplessness).
• Delirium (disturbed mental state).

Bronchial Asthma

Definition

Wheezing

Wheezing is a high-pitched whistling sound produced while breathing.

It is associated with difficult breathing.

Wheezing occurs due to obstruction of air passage because of bronchiolar constriction.

Causes of Bronchial Asthma

1. Leukotrienes released from eosinophils and mast cells during inflammation cause bronchoconstriction (bronchospasm).
2. Allergic substances such as foreign proteins produce hypersensitivity of nerve fibers to larynx and nose resulting in asthma.
3. Pulmonary edema with congestion of lungs caused by left ventricular failure leads to asthma. Asthma developed in this condition is called cardiac asthma.

Features of Bronchial Asthma

1. Asthma is a paroxysmal (sudden) disorder because the attack commences and ends abruptly. During the attack, the difficulty is felt both during inspiration and expiration. More difficulty is experienced during expiration.
2. Because of difficulty during expiration, lungs are not deflated completely, so that the residual volume and functional residual capacity are increased.
3. Tidal volume, vital capacity, FEV1 and alveolar ventilation are decreased.
4. Carbon dioxide accumulates, resulting in acidosis, dyspnea and cyanosis.

Pulmonary Edema

It is caused by increased pulmonary capillary pressure (due to left ventricular failure or mitral valve disease), pneumonia, and breathing harmful chemicals.

Features of pulmonary edema are severe dyspnea and cough.

Death occurs in severe conditions.

Pleural Effusion

Pleural effusion is the synonym of hydrothorax.

Pleural effusion occurs because of blockage of lymphatic drainage, flow of fluid from pulmonary capillaries and inflammation of pleural membrane.

Pulmonary Tuberculosis

Tuberculosis is the disease caused by tubercle bacilli.

This disease can affect any organ in the body. However, the lungs are affected more commonly.

Infected tissue is invaded by macrophages and later it becomes fibrous.

Affected tissue is called tubercle.

Initially, alveoli in the affected part become non-functioning.

In severe conditions, the destruction of lung tissue is followed by formation of large abscess cavities.

Emphysema

Damage of lung tissues results in loss of alveolar walls.

Because of this, the elastic recoil of lungs is also lost.

Causes of Emphysema

• Cigarette smoking.
• Exposure to oxidant gases.
• Untreated bronchitis.

Chronic emphysema could lead to hypoxia, hypercapnia, severe dyspnea and death.

Cystic Fibrosis

Due to gene mutation, mucus lining the organs becomes thick and sticky.

In respiratory tract this mucus obstructs the air passage and causes breathing difficulty.

In lungs, cystic fibrosis causes frequent infections such as bronchitis and pneumonia resulting in inflammation, cough and wheezing.

Over the period of time, this disease causes permanent damage of lung tissues with formation of cysts (sacs filled with fluid) and fibrosis (scar tissues).

Hence, the name cystic fibrosis.