Management of emergencies and cardiopulmonary resuscitation


Airway and Breathing
Cardiac Arrest and Inadequate Circulation

CARDIAC ARREST AND INADEQUATE CIRCULATION

Cardiac arrest exists when there is no detectable heartbeat, major pulse or other sign of cardiac output; the patient is completely unresponsive and breathing stops within a few seconds. Unlike breathing, it is less obvious when there is no blood circulation, especially in patients with dark skins.

You must look for and make the specific diagnosis of circulatory arrest:

Having made the diagnosis, the immediate first step must be to do external cardiac massage (ECM). This must start immediately you decide that there is no circulation. Do not hesitate to start ECM if you cannot detect a heartbeat. The action of ECM will alert others more effectively than simply saying “There’s a cardiac arrest”. It is best to do both.

In cardiac arrest, keep ventilating and continue ECM until there is a response or you decide to stop treatment.

ECM should be performed while positioned well above the patient (Figure 13.1).

Figure 13.1

At this stage, you are temporarily averting the fatal consequences of cardiopulmonary arrest. The ABC routine is life saving, but only for a few minutes. Some other treatment must be given and normal circulation must be restored if the patient is to survive.

Two people should be assigned duties: ventilation and ECM. They will need relief when they get tired. Assign a third person to feel for the femoral pulse and report to you if it returns.

Your next priority is to diagnose the problem with the circulation and correct it. Your action to achieve this will depend on the facilities you have. You may have no electronic monitoring devices or you may have an ECG and perhaps a defibrillator.

Very often, a device is present in the hospital but does not work when needed or it has to be brought from somewhere else, causing delay. It may be locked in someone’s office. You may have an ECG monitor, but have no chest electrodes, or they have dried up through age or are of the wrong type. The mains power lead may have been lost or stolen. The hospital generator may have to be switched on.

There may, therefore, be many reasons why you think that you have ECG diagnosis at your hospital whereas in fact you do not. Check now if, in fact, an ECG monitor is available and if it works when connected to a patient. Remind yourself how to connect it up.

Do not waste time during a cardiac arrest trying to make an ECG machine work.

When there is no ECG diagnosis

Epinephrine (adrenaline) is life saving in many cases of cardiac arrest. Always use it once the diagnosis is made, even if you do not know the cause of the arrest.

It is usual to abandon CPR if there is no response after 20–30 minutes or if three doses of epinephrine have not produced signs of a heartbeat.

When there is an ECG diagnosis

As you start ECM, call for the ECG monitor. In cardiac arrest, there are three key ECG appearances at cardiac arrest:



Unless you are familiar with the normal sinus rhythm trace (and the benign arrhythmias which do not require immediate treatment), you will not be able to make a decision based on what is shown there.

In order of frequency of occurrence in countries where ischaemic heart disease is rare, the cardiac arrest rhythms are as follows.

Asystole

You will see a straight or smooth wavy line. You may see occasional widened complexes, but no pulse can be felt in the femoral artery. There should always be some electrical activity when ECM is being carried out. A steady straight line may mean the machine is not connected.

Asystole is the terminal event in many severe illnesses, but may be acutely caused by:

Treat with epinephrine as above and atropine. The prognosis is very poor.

Pulseless electrical activity (sinus rhythm)
This is also called electromechanical dissociation (EMD). There is a near-normal ECG pattern, but no detectable pulse. There are many causes of this situation and, in the heat of the moment, you have to think clearly. Some of the important causes are:

For the anaesthetist, the first three are the most common.

To treat pulseless electrical activity

Look for a cause. Give epinephrine, if needed.

A glance at the list above should tell you that some of the causes are reversible without drug treatment and that this may not be a true cardiac arrest. If you can withdraw or correct the cause of the arrest (by switching off halothane, increasing intravenous fluids, correcting a problem with the anaesthesia circuit), this will be safer than giving an intravenous bolus of epinephrine.

If there is no detectable circulation after two or three minutes of CPR, even with a diagnosis and corrective measures, give epinephrine as for asystole. The prognosis is good, if the cause can be found.

Ventricular fibrillation

A coarse or fine jagged line denotes chaotic ventricular activity (Figure 13.3). A defibrillator is required.

To treat, defibrillate. This needs training and experience.

Figure 13.3
1	Start with 2 x 200 joules DC shock (2 joules/kg body weight) followed by 360 joules if sinus rhythm does not return promptly.
2	Put electrode jelly on the chest, check the orientation of the paddles (labelled “apex” and “sternum”) and press them firmly on the chest.
3	Tell everyone to stand clear and shock across the heart. No one should be touching the patient or anything that is touching the patient, including the resuscitation bag, as most things conduct electricity.

If you have no defibrillator, a chest thump or epinephrine may produce sinus rhythm.

Prognosis is good, especially if the precipitating cause was halothane and epinephrine interaction or hypoxia.

Haemorrhage

External bleeding can be controlled, usually with pressure. Bleeding into body cavities may be apparent only later; for example, when the circulation has been restored and the rise in blood pressure causes more bleeding and a second fall in blood pressure.

Shock

Shock is a pathological, life threatening condition in which the oxygen supply to the tissues of the body fails. The cause is usually one of the following:

There may be more than one cause of shock. In surgical patients, look for hypovolaemia and sepsis first.

Heart failure is beyond the scope of this book. The prognosis is poor when it occurs intra- or postoperatively. Fluids will not help as the circulation is overloaded.

Unconsciousness

Unconsciousness may have many causes including:

Assess the response to stimuli, look at the pupils initially and re-examine them later to follow progress. Look for unequal pupils or other localizing signs that may show intracranial haematoma developing.

In many instances, you may attend to and stabilize other systems first and await the return of consciousness as cerebral perfusion and oxygenation improves. After cardiac arrest, a patient who initially had fixed dilated pupils may show smaller pupils after effective CPR. This indicates that a favourable outcome may be possible.

The supine unconscious patient with a full stomach is at grave risk of regurgitation and aspiration due to the unprotected airway. However, if a comatose patient has a clear airway and vital signs are normal:

•	Avoid intubation as this will involve drug administration and complicate the subsequent diagnosis
•	Nurse the patient in the recovery position
•	Monitor the airway and await progress and diagnosis (Figure 13.4).
Figure 13.4

During CPR, ask yourself: is the patient responding? If not, why not?

Airway and Breathing
Cardiac Arrest and Inadequate Circulation