Use of the AED in the Dental Practice

If someone’s heart stops, their chances of survival are greatly increased if they receive good CPR and early defibrillation.
An AED is a device that gives a high energy electric shock to the heart.

Defibrillation is the passage of an electrical current across the myocardium to depolarise a critical mass of heart muscle simultaneously, enabling the natural “pacemaker” tissue to resume control.

Following the onset of ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) cardiac output ceases and cerebral hypoxic injury starts within 3 minutes.

VF
In VF the ventricular myocardium depolarises randomly.
The ECG shows rapid bizarre irregular waves, of widely varying frequency and amplitude.

pVT
Ventricular Tachycardia, particularly at higher rates or when left ventricle is compromised, may cause profound loss of cardiac output.
Pulseless VT is managed in the same way as VF.
The ECG shows a broad, complex tachycardia.
In monomorphic VT (showing little or no variation) the rhythm is regular (or almost regular) at a rate of 100-300 bpm.

Successful defibrillation is defined as absence or VF or pVT at 5 seconds after shock delivery, although the ultimate goal is Recognition Of Spontaneous Circulation (ROSC).

Transthoracic impedence

Ensure there is good contact with the skin.

• Remove all clothing from the chest area including bras using tuff cut scissors which should be stored with the defibrillator
• Move any jewellery (necklaces etc.) out of the way of the pads.
  You do not need to remove nipple rings unless they interfere with the placement of the pads
• If the chest is hairy, a razor should be available to shave the area where the electrodes are to be placed
• If there is sweat, blood or debris on the chest, clean it with wet wipes and dry wipes (towel) which should be stored with the defibrillator

AED Prep Kit

Electrode Position

For adults, place one pad on the right side of the chest, just below the collarbone (mid clavicular). Place the other pad on the lower left side of the chest (mid axiliar)

Check manufacturers guidelines for your AED

• If you are using an AED you do not need to choose any shock energy as the device will do this automatically. Just listen and follow the prompts
• Potential failure of the device can be operator error.
• Most AED’s are supplied with a DVD or video available on the manufacturer’s website.
• Ensure that the whole dental team including non-clinical staff are familiar with your model of AED and know where it is stored.
• All AED’s are designed to be used by lay people with no formal training. However, being thoroughly familiar with your device will reduce delay in an emergency

Shock Sequence

For all cardiac arrests start CPR and use the AED to assess the rhythm as soon as it arrives:

• Although defibrillation is key to the management of patients in VF and pVT, continuous uninterrupted chest compressions are also required to optimise the chances of ROSC
• Even short interruptions to chest compressions (to deliver rescue breaths and analyse rhythms) decreases the chance of successful defibrillation

The aim is to ensure that chest compressions are performed continuously throughout the resus attempt, pausing briefly only to enable specific interventions. Every 5 second increase in the pre-shock pause (analysing stage) almost halves the chance of successful defibrillation. Consequently defibrillation must always be performed quickly and efficiently in order to maximise the chances of ROSC

Do not deliver a shock if anyone is touching the patient
Do not touch any equipment such as IV stands or beds when a shock is being administered

Safe use of oxygen during defibrillation
Sparks in an oxygen rich environment can cause a fire – although no fires have been reported in association with the use of self adhesive pads.
However, we should still take thorough precautions to minimise risk

• Remove any oxygen masks or nasal canula and place at least 1 metre from patient’s chest
• If using BVM place at least 1 m from patients chest
• If a supraglotic airway has been inserted then the bag can remain, as the oxygen is in a closed system

Can I use an AED on a patient who has a pacemaker?
When a patient needs external defibrillation, effective measures to try to restore life take priority over concerns about any implanted device such as a pacemaker, implantable cardioverter defibrillator (ICD), implantable events recorder or neurostimulator.

Current Resus Council (UK) guidelines are followed, but awareness of the presence of an implanted device allow some additional measures to optimise outcome:

• To minimise the risk of damage to the device, place the defibrillator electrodes away from the pacemaker or ICD (at least 10-15 cms) without compromising effective defibrillation
• If necessary place the pads in the anterio-posterior, posterio-lateral or bi-axiliary positions

During a shockable rhythm, external defibrillation should be attempted in the usual way.

Start CPR as explained in the previous lesson.

• As soon as the AED arrives, switch it on and follow the visual and audio prompts to attach the pads ensuring the chest is clean and clear
• If more than one rescuer is present, continue CPR while the AED pads are being applied
• If no shock is indicated, continue CPR
• Ensure that someone has called 999/112 for an ambulance

Watch this video to see how to perform CPR and use an AED on an adult:

Most AED’s have either paediatric pads to attach to the chest or a paediatric setting which reduces the size of the shock delivered.

• If no paediatric pads are available, it is still better to use the adult AED pads
  In general terms an adult is defined as any person over 25Kg (55lbs) which is approximately the weight of a 6 year old
• If you are using adult pads on a child or baby, place one pad in the centre of the chest and the other in the centre of the back

The reason that children’s pads are smaller and placed in a different position is to obtain the correct transthoracic impedence

NOTE: For babies under 1 year check manufacturers guidelines before using an AED