Introduction to

Emergency Medicine

Dr. Tarek Atia

Book: The new manual of basic emergency

procedures; Firs aid and updated CPR

By: Professor Mohamed A. Seraj 2nd edition

A-2

Subspecialty of Emergency Medicine

Pediatric Emergency Medicine

Toxicology

Sports Medicine

Undersea and Hyperbaric Medicine

Challenges to Emergency Medicine

Interaction with difficult, intoxicated, or violent patients or

family members

Work in a “fishbowl” without 20/20 hindsight

Finding follow-up or care for uninsured

Limited resources

High stress

Scope to emergency medicine

What make case emergency:

1. If acute

2. Life threatening

3. Chance of permanent morbidity.

Asking question:

I) Multiple casualty

Within capability of the hospital.

Take patient with most serious situation.

II) Mass casualty

Beyond capability of the hospital.

Disaster

– Take patient with least serious case .i.e: the least intervention.

Clean the hospital.

The golden hour:

Expression that time after the accident is of the

highest value.

Because there is high chance to reverse the situation.

THE EARLIER THE BETTER.

II)Hospital care:

Behavior and treatment different between Emergency Room and word.

Because in ER there is no time (deal with the core of the problem).

– Approach to ER pt:

History:– Allergy– Medication– Past illness/pregnancy. SMPLE Hx– Last meal.– Event/ environment.

- Secondary survey: full history and exam and

investigation.

- Tertiary survey: must be seen by consultant next

morning.

- Re-evaluation.

– Definitive care: refer him to specialist.

Don’t forget:

– Records.

– Consent for treatment.

– Forensic evidence. (Bullet, knife, clothes).

– Assume pt has cervical injury.

– Finally don’t be panic…

ANATOMY AND PHYSIOLOGY

OF THE CARDIOVASCULAR

SYSTEM

ANATOMY OF THE CARDIOVASCULAR SYSTEM:

- It is composed of: The Heart The blood vessels

Arteries Capillaries Veins

THE HEART:

Fist-sized organ situated in the center of the chest,

between the sternum and the spine and above the

diaphragm.

It is surrounded by the lungs except in small area in front

of the heart known as the bare area and the area against

the spine.

- It has a hollow tough muscular wall

surrounded by the pericardium.

- It is divided into right and left side and each side has 2

chambers, right atrium and ventricle and left atrium

and ventricle.

THE VASCULAR SYSTEMIt comprises:

Ateries

Thick-walled, carrying blood from the heart under high

pressure.

Capillaries

Thin network of one cell layer.

Veins

Thin-walled vessels that carry blood under low pressure back

to the heart.

Pulmonary Circulation

Pulmonary Circulation

Systemic Circulation

Aorta and Major Arteries

Arteries of the Head and Neck

Arteries of the Brain

PHYSIOLOGY OF THE HEART1- Heart pumps blood from the rt. ventricle into the pulmonary

artery to the lungs to purify the blood and from the left ventricle

into the aorta to distribute blood to the rest of the body.

2- Arteries carry blood away from the heart

3- veins carry blood back to the heart

4- Exchange of gases takes place in the capillary system throughout

the body.

Functions

To purify the blood through the pulmonary capillary

system

To provide oxygenated blood to all tissues, through

the systemic capillary system.

The heart beats 60-80 beats per minute during rest. The amount

of blood pumped by a single beat and known as the stroke

volume is ~70ml.

The heart pumps ~5 lit/min.Cardiac output is equal to stroke

volume multiplied by heart beats/min. That is to say

70x70=4900 (5 liters/min).

The heart can beat faster, up to 180-200 beats/min during

exercise, so it is capable of pumping up to 35 lit. per minute.

Blood supply to the Myocardium:

Two coronary arteries, right and left, originate from the

first part of the aorta.

They are divided into several branches which encircles

the heart to supply the myocardium.

The coronary arteries are end arteries. There is no

venous coronary artery.

Extrinsic Innervation of the Heart

The heart is stimulated by the

sympathetic cardioacceleratory

center

The heart is inhibited by the

parasympathetic

cardioinhibitory center

Conduction system of the Heart

The contraction is known as systole and is followed by a

relaxation period known as diastole.

During systole the heart pump blood into the vascular

system, while during diastole the heart is relaxed and

receives venous return and recharges to prepare for the

next beat.

Electrocardiography (ECG)

Cardiac Cycle

Cardiac cycle refers to all events associated with blood flow

through the heart

– Systole – contraction of heart muscle

– Diastole – relaxation of heart muscle

Phases of the Cardiac Cycle

Ventricular filling – mid-to-late diastole

– Heart blood pressure is low as blood enters atria and flows

into ventricles.

– AV valves are open, then atrial systole occurs.

Phases of the Cardiac Cycle

Ventricular systole

– Atria relax

– Rising ventricular pressure results in closing of AV valves

– Isovolumetric contraction phase

– Ventricular ejection phase opens semilunar valves

Phases of the Cardiac Cycle

Isovolumetric relaxation – early diastole

– Ventricles relax

– Back-flow of blood in aorta and pulmonary trunk closes

semilunar valves

Dicrotic notch – brief rise in aortic pressure caused by

backflow of blood rebounding off semilunar valves.

Phases of the Cardiac Cycle

Figure 17.18a

Phases of the Cardiac Cycle

Heart Sounds

Heart sounds (lub-dup) are associated with closing of heart valves

At RestHeart beat/minute = 70x1 = 70

Heart beat/hour = 70x60 = 4,200

Heart beat/day = 4200x24 = 100,800

Heart beat/year = 100,800x365 = 36,792,00

 

Volume pumped/min = 5lit

Volume pumped/hour = 5x60 = 300 lit

Volume pumped/day =300x24 = 7200 lit

Volume pumped/year = 7200x365 lit =2,628,000lit

THE RESPIRATORY

SYSTEM

The respiratory system has 4 components

– The Airway

– The neuromuscular system 

– The Alveoli 

– The vascular system, arteries, capillaries & veins

1. THE AIRWAY Upper airway

-Nose and mouth

-Pharynx

-Larynx Lower airway

-Trachea

-Bronchi (right and left)

-Bronchioles

2. NEUROMUSCULAR SYSTEMComprises of: Respiratory centre in the brain Nerves Muscles of respiration These are:

–Diaphragm

–Intercostal muscles

–Some muscles in the neck and shoulder girdle Chest cage: protects the lungs and the heart

–Spine at the back

–Sternum in front

–ribs around

A- Respiratory centre in the brain &Nerves

Muscles of respiration

Chest cage

Chest cage

3. THE ALVEOLI

Minute air sacs, millions in number. They are made

of a very delicate thin membrane of one cell layer

forming a fine network. The capillaries are on the

outer side of the alveoli where exchange of gases

is carried out.

4. PULMONARY VESSELS

Arteries carry dark blood with low oxygen levels from the

heart to the fine network of capillaries where O2 is picked-up

by the blood and CO2 is expelled in to the alveoli. The

oxygenated blood is the carried out to the left side of the

heart by the veins.

PHYSIOLOGY OF RESPIRATION:The function of the respiratory system is to pick-up

oxygen from the air and expel carbon dioxide into the

air. Metabolism is a continuous process which needs

oxygen to function and as a result of this process,

carbon dioxide is produced. The Cardiovascular

system transports oxygen from the lungs to the cells

and transports carbon dioxide from the cells to the

lungs for elimination.

The breathing mechanism is controlled and influenced

by the respiratory centre in the brain and primarily

the rate and depth of breathing is stimulated by

carbon dioxide in the arterial blood. As the level rises,

the respiratory centre sends a continuous parade of

signals via the nerves to respiratory muscles.

This will result in an increasing rate and depth of breathing

until the level of carbon dioxide falls, then the breathing

rate and depth are returned to normal. This is known as

feedback mechanism between carbon dioxide level and

the rate and depth of breathing.

Inspired Air Expired

O2 21% 16%

CO2 0.03% 4%

N2 79% 79%

Humidity Less More

During respiration, 5% of oxygen passes from atmospheric air

into the blood through alveolar and capillary walls and 4% of

carbon dioxide is eliminated from the blood into the expired

air. Inspiration is an active process while expiration is a

passive process.