In one breath
CPR is the organized treatment, begun at once, of a patient whose heart and breathing have both stopped, usually because the ventricles are fibrillating or the heart is in asystole. It has two aims: ventilate the lungs so the PaO₂ is kept up, and get the heart pumping so the circulation keeps going. It runs in three steps: initial evaluation with basic life support (airway, breathing, chest compressions), then advanced life support (early defibrillation, 100% O₂ with intubation, drugs, pacing), then post-resuscitation care.
Builds on: Artificial respiration · Hypoxia
What CPR is
- Cardiopulmonary resuscitation (CPR): treatment, both supportive and specific, begun at once in a patient whose cardiac and ventilatory activity have stopped.
- It needs a trained, experienced team: the life-saving steps work only when they are done properly.
Indications
CPR is indicated in cardiorespiratory arrest. Your book lists 19 situations that commonly lead to it; grouped, they are:
- Heart: primary arrhythmias; arrhythmias with myocardial infarction; acute or healed MI; myocarditis; cardiomyopathy (dilated or hypertrophied); cardiac tamponade; cardiac surgery
- Lungs and airway: drowning; airway obstruction; pulmonary embolism; acute pulmonary edema; chronic lung disease (rarely)
- Injury: accidents; head injury; electric shock
- Drugs and others: poisoning; anaphylactic shock; muscle relaxation during surgery; acute psychological trauma
Mechanisms and signs of arrest
- Two usual mechanisms: cardiac asystole and ventricular fibrillation (VF).
- Features: no heartbeat, and no pulsation in the large arteries.
- Signs: pallor, cyanosis and gasping, then complete arrest of breathing and dilated pupils.
Objectives of CPR
- Ventilate the lungs well enough to maintain the arterial PO₂.
- Start the heart pumping and support it, so that an effective circulation is maintained.
The three steps
| Step | What it covers |
|---|---|
| 1. Initial evaluation + basic life support | assess, open the airway, ventilate, compress the chest |
| 2. Advanced life support | defibrillation, O₂ and intubation, drugs, pacing |
| 3. Post-resuscitation care | treat the cause, protect the brain |
Initial evaluation
- Assess four things: consciousness, breathing movements, skin colour and the arterial pulses.
- If a foreign body stuck in the airway caused the arrest, dislodge it with the Heimlich maneuver.
- Worth knowing, though not in your pages: in the Heimlich maneuver the rescuer stands behind the patient and gives sharp upward thrusts into the upper abdomen, above the navel. The sudden rise in pressure drives air out of the lungs and pushes the object out.
Basic life support (BLS)
BLS begins at once, and a clear airway with breathing comes first: if ventilation is not adequate, restoring the circulation achieves nothing.
- Check responsiveness: shake the patient gently.
- Position: lay the patient on a firm, flat surface.
- Clear the mouth of vomit, blood, mucus or debris.
- Open the airway (head tilt–chin lift): press one palm on the forehead to tilt the head back while the other hand supports the chin. The neck extends, the tongue lifts away from the back of the throat and the airway opens.
- Ventilate by one of three methods (step by step in Artificial respiration):
- mouth-to-mouth for adults, at 10–15 breaths a minute;
- mouth-to-nose, preferred in infants and children;
- Holger Nielsen, usually kept for a respiratory cause such as drowning.
- Feel the carotid pulse for at least 10 s, so you don’t miss a pulse that is slow, irregular or very faint.
- No carotid pulse → external cardiac massage (below).
- Pulse back → carry on ventilating as needed.
External cardiac massage
- If the patient is in bed, put a hard board under the back.
- Place the heel of the hand about 3 cm above the xiphoid process, a little to the left, keeping the fingers off the chest.
- With your shoulders vertically above the patient’s chest, push the sternum straight down toward the spine.
- The rescuer managing the airway feels the carotid pulse from time to time to judge whether the compressions are adequate.
| Measure | Your book’s value |
|---|---|
| Hand position | ~3 cm above the xiphoid, to the left |
| Depth | 4–5 cm |
| Rate | 80–100/min |
| Compression : ventilation | 5 : 1 |
Your book's CPR numbers are old
Write your book’s figures in the exam: they are what the examiner marks. Worth knowing, though not in your pages: resuscitation guidelines (AHA) have since changed them, and any BLS course or clinical posting will teach these instead:
- Order: compressions first (C-A-B), not airway first (A-B-C)
- Rate: 100–120/min, not 80–100
- Depth: 5–6 cm, not 4–5 cm
- Ratio: 30 : 2, not 5 : 1
- Hands: centre of the chest, on the lower half of the sternum
- Pulse check: no longer than 10 s, not “at least 10 s”
- Pauses, including for intubation: under 10 s, not up to 30 s
- The precordial thump and routine sodium bicarbonate are no longer used, atropine has been dropped for asystole, and cooling after an arrest is now called temperature control (targeted temperature management).
Why compressions move blood
Worth knowing, though not in your pages: two mechanisms are thought to work together.
- Cardiac pump: the heart is squeezed between the sternum and the vertebral column. Blood is forced into the aorta and pulmonary artery, and the closed AV valves stop it flowing back. On release, the chest recoils and the heart refills from the veins.
- Thoracic pump: each compression raises the pressure throughout the chest and drives blood into the arteries outside it, while the veins at the thoracic inlet collapse and their valves block backflow.
- Even good compressions produce only a fraction of the normal cardiac output, which is why they must be deep, fast and rarely interrupted.
Advanced life support (ALS)
ALS has two parts: primary and adjunctive therapies.
Primary therapies
- Defibrillation
- One of the most important treatments in CPR; start it as early as possible.
- In arrest from VF, the time from the arrest to a successful shock is the major determinant of survival.
- A fibrillating ventricle makes no effective contractions, so it moves no blood. In your book’s words, the shock turns the fibrillation into flutter or a normal rhythm, so effective contractions and pumping return.
- Adrenaline and sodium bicarbonate are given intravenously.
- Airway management and O₂ therapy
- Give 100% O₂.
- A qualified person should pass an endotracheal tube as soon as possible.
- BLS must not be delayed or interrupted for more than 30 s for intubation.
A slip in your book: what the shock does
Worth knowing, though not in your pages: a defibrillating shock does not turn VF into flutter. It depolarizes the whole ventricular myocardium at once; with every fibre refractory together, the chaotic wavelets die out and the SA node can take over as pacemaker again.
Adjunctive therapies
| Therapy | Dose | Used for |
|---|---|---|
| Self-induced cough | vigorous coughing | arrest noticed before consciousness is lost |
| Precordial thump | one quick blow | VF or asystole |
| Atropine sulphate | 0.5 mg IV every 5 min | bradycardia; may help in asystole |
| Sodium bicarbonate | 1 mEq/kg IV every 10 min | arrest from hyperkalemia or acidosis |
| Pacemaker | pace early | refractory bradyarrhythmia, persistent asystole |
- Coughing hard keeps a small flow of blood reaching the brain for a while, until definitive treatment can begin.
- Pacing helps when the fault is in impulse formation.
Other ways to assist ventilation
Your book names the Sylvester-Brosche, Drinker’s, Paul-Bunne and rocking methods, none of them in routine use.
Worth knowing, though not in your pages: the first is usually spelt Silvester (Silvester–Brosch): the patient lies on the back, and the arms are swept above the head for inspiration, then folded onto the chest and pressed for expiration. The rocking method (Eve’s) tilts the patient head-down and head-up on a stretcher, so the abdominal organs push the diaphragm up and then let it fall.
When to stop: cerebral death
Some patients never regain their own breathing and circulation, whatever is done. These signs suggest cerebral death, and further resuscitation is then unproductive:
- deep unconsciousness that persists
- no breathing
- no reflex responses
- no pupillary reaction to light (your book prints “papillary”)
Post-resuscitation care
- In a well-equipped hospital, long respiratory support is rarely needed, and the circulation settles quickly.
- The aim now is to treat the disease that caused the arrest.
- A long arrest leaves hypoxic encephalopathy and cerebral edema. Induced hypothermia is now used to cut metabolic demand and reduce the edema.
Two rules from the book’s summary
- Cardiac massage is for trained hands. Done badly it does not work, and it can fracture ribs.
- Adjunctive therapy and assisted ventilation start together, not one after the other.
Draw it: CPR as a flow chart
- Top box: “Collapse: unresponsive, not breathing, no carotid pulse”.
- Arrow down to “Initial evaluation”: consciousness, breathing, colour, pulses; Heimlich maneuver if a foreign body is stuck.
- Arrow down to a “Basic life support” box with three lines: Airway (clear the mouth, head tilt–chin lift); Breathing (mouth-to-mouth, 10–15/min); Circulation (compressions 4–5 cm deep, 80–100/min, 5 : 1).
- Arrow down to an “Advanced life support” box: early defibrillation, 100% O₂ and intubation, adjunctive drugs and pacing.
- Side arrow from that box to “No response: signs of cerebral death → stop”.
- Main arrow down to “Post-resuscitation care”: treat the cause, protect the brain (induced hypothermia).
Exam-answer skeleton: "Cardiopulmonary resuscitation" (short note)
- Define CPR and state its two objectives (keep the PaO₂ up, keep the circulation going).
- Indications, grouped: heart, lungs and airway, injury, drugs and others; the two mechanisms, VF and asystole.
- Signs of cardiac arrest.
- Initial evaluation, then BLS: position, clear the mouth, head tilt–chin lift, ventilate, check the carotid pulse.
- External cardiac massage with your book’s numbers (hand position, 4–5 cm, 80–100/min, 5 : 1).
- ALS: early defibrillation, 100% O₂ and intubation, then the adjunctive therapies with doses.
- Signs of cerebral death, and post-resuscitation care (treat the cause, induced hypothermia).
- Draw the flow chart.