Below is an outline of some of the basic principles.
ALS courses are run by hospitals, other health care providers and private companies for medical staff, including doctors, nurses and allied healthcare professionals. Most clinical staff will be expected to complete an ALS course every four years.
- Check for danger when approaching the patient. Look for relevant dangers for the current environment.
- Check the patient for a response – put your hand on the patient’s forehead and shake their shoulders and shout. This is to prevent causing any further damage if there is a neck injury.
- Shout for help – if there is no response then shout for help
- Check signs – check if the patient is breathing by looking and feeling for 10 seconds. At the same time, feel for a pulse in the neck. If the patient is not breathing (regardless of pulse), then go and get help. Either call for an ambulance, or dial 2222, stating ‘cardiac arrest’ and the location. Repeat a couple of times
- Return to the patient and immediately start CPR – do 30 chest compressions to two breaths. Continue this until help arrives. If there is more than one person, one can do the breaths, and one the compressions, and make sure you swap over every 2 minutes.
- If in hospital, use a pocket mask , or better, a bag and mask to do the breaths. When using the pocket mask stand at the patients head looking down the length of their body. Hold on the mask with both hands to create a good seal. You should attach both masks (whichever you use) to oxygen at the wall at 15L/min. By doing this you are breathing a more concentrated oxygen into their lungs when you breathe (or squeeze the bag). Using room air alone and a breathing mask, you can get sats of 55%. Using 15L/min of O2 you can get up to 85%.
- DON’T WORRY ABOUT COPD – it is the respiratory drive that is affected in COPD – but as they are unconscious they don’t have a respiratory drive, and anyway you are providing their ventilation, so even if they did have one, you are over-riding it!
- If no-one is willing to give breaths, then you don’t have to. Just keep giving compressions
- The aim of BLS is to provide perfusion until better help arrives. Doing this can prolong the chance of survival by perhaps 5 minutes or so. It is highly unlikely that a patient will revive from a cardiac arrest from CP alone
- Heat tilt and chin lift – the purpose of this is to straighten the trachea, but it also lifts the tongue out of the way and keeps it away from the posterior pharyngeal wall. The jaw thrust is an alternative method that is particularly useful if the patient has a neck injury and you are worried about moving the neck.
- Further help arrives – at this point, somebody senior will take control and deal out jobs. Somebody will continue CPR whilst someone else prepares the defibrillator. There may also be relatives who insist on staying in the room. There will probably be a member of staff delegated to keep these relatives out of the way at the back of the room somewhere, and explain to them what is going on.
- The person who arrives at this stage should check the pulse to make sure it is actually a cardiac arrest! – only ever check the carotid pulse – or any other central pulse, don’t use peripheral pulses.
- Preparing the defib – whilst CPR is continuing, then apply the pads to the chest. The one with the white lead goes under the right clavicle, and the one with the red lead goes at the apex beat location.
- Before applying the pads, make sure the skin is dry, and there is not excessive hair. You might have to shave off excessive hair if it is present.
- Piercings may appear inconvenient but you should just leave them be in these situations. There is no point taping them because hospital tape is not insulating tape! Just be sensible, and don’t stick your pads over them. If necessary you might have to put the right hand pad on the patients right hand side (roughly apex equivalent) if there arre piercings in the way, but this is VERY rare.
- The defib also acts as an ECG – turn on the defib into auto mode (shock-advisory mode). This mode will take an ECG and analyse it, and will then tell you if the rhythm is shockable or not (more on this later). It takes up to 6 seconds for it to analyse the rhythm. The machine is 99.8% reliable at identifying the right rhythm – and no manufacturer has ever been sued.
- Press ‘analyse’. You need to make sure everyone in the room is not standing around the patient, and that no-one is touching the ECG wires as this can interfere with the reading. Also mobile phones can cause interference, so everyone in the room should have theirs turned off. The machine will just say if the rhythm is shockable or not.
- Always make sure you remove oxygen before giving the shock!
- Shockable rhythm – warn everyone to stand clear, and have a good look around to make sure everyone is stood clear, then shout stand clear again, and then press the shock button. A shock will be delivered. Regardless of the outcome, do CPR for another two minutes. Even if the ECG appears totally normal, it is likely the heart isn’t pumping properly yet, so keep doing CPR for a further two minutes. After two minutes, repeat the ‘analyse’ test. If the first shock was successful, then the rhythm of the heart will be back to normal, and the machine will tell you it is a non-shockable rhythm. It will be worth checking the pulse – make sure people aren’t doing CPR when you check the pulse! If there is a pulse, then yay! You have done your job properly. If no pulse, then see below for treating as a non-shockable rhythm. If the machine says it is a shockable rhythm, then repeat the shock procedure, and do a further CPR for 2 minutes, then analyse again. Keep going until there is a non-shockable rhythm present, or until a senior member of staff decides to discontinue.
- Before the 4th shock you should consider giving amiodarone – this is an anti-arrhythmia drug, typically used in tachyarrhythmias. It has common side effects, but is still used in practice when other anti-arrhythmia drugs have failed.
- Note that with breast implants there is a very small chance they will pop from the defib, but this is so ridiculously small it is not worth worrying about. There is actually more chance they will pop from CPR!
- Power output – a normal shock is abut 150J. Some machines increase the level of the shock with each subsequent delivery (up to about 360J), however the evidence for this is limited, and so many machines just keep the shock level at 150J each time.
- Non shockable rhythm – continue doing CPR for two minutes. You can keep analysing to see if they go into a shoackle rhythm. Continue the cycle until a senior member of staff decides to discontinue.
- Shockable rhythms – 1mg adrenaline should be given after the first (or third?) shock if VT/VF persists, and then every 3-5 minutes after that. It causes vasoconstriction, and thus reduces peripheral circulation, and so increases the chance of enough oxygen going to the heart and brain (less goes to the limbs).
- Non-shockable rhythms – 1mg adrenaline should be given straight away (as soon as you identify its non-shockable) and then every 3-5 minutes subsequently
- Atropine should be given as a one off dose of 3mg at the very start of ALS. This drug blocks muscarinic receptors and thus reduces the nervous stimulus from the vagus nerves to the heart, ideally allowing the heart to ‘reset’ and thus improve the chances of getting back into a normal rhythm.
- Other stuff – whilst the cycle of CPR and shocking is going on, you need to try to identify and rectify underlying causes – however, remember that the BLS is more important than finding the underlying cause, and only try to find the cause once you are happy the adequate ventilation and perfusion is being undertaken.
- Before identifying causes – you should get IV access – both for possible blood samples and to administer drugs
- When giving drugs during cardiac arrest – be sure to flush them through lots! Because there is no circulation, then drugs given IV aren’t going to reach most of the body on their own so be sure to flush it with loads of saline.
- Identifying causes:
- Tension pneumothorax is a very common cause in asthmatics – so always keep this in the back of your mind!
- The causes can be split into the 4t’s and 4h’s – look at cardiac arrest notes for these causes
- Hypovolaemia is another very common one – so basically check for trauma, and signs of AAA. Also possibly caused by severe burns or vomiting.
- When to stop – this is a decision you probably won’t have to make for a long time! Generally if a patient is in hypothermia then ALS will continue for longer – because they have a slower metabolism and thus less damage is likely to have been done during the period of hypoxia. You should also try to bring these patients up to a reasonable temperature; by giving them 37’C air and warm IV fluids
- Cold + clammy
- Very low bp (dizzy, drowsy)
- Rapid breathing
The rationale for delivering a precordial thump is that it generates a mechanical energy, which is converted to electrical energy, which then may be sufficient to achieve successful cardioversion (Kohl et al, 2005). Following the onset of VF, the threshold for successful defibrillation rises steeply after a few seconds. In all reported cases of successful use of the precordial thump for VF, it was delivered within 10 seconds (Resuscitation Council (UK), 2006). This demonstrates the importance of witnessing the collapse.
A precordial thump should be considered if cardiac arrest is confirmed rapidly following a witnessed and monitored (ECG) sudden collapse (VF or VT) if the defibrillator is not immediately at hand (Resuscitation Council (UK), 2006).
A research study (American Heart Association, 2006) looked at 187 episodes of VF, VT, supraventricular tachycardia, asystole and complete heart block where a precordial thump was delivered. The results were as follows:
- Ninety-one (49%) reverted to normal sinus rhythm;
- Seventy-seven (41%) had no change in rhythm;
- Nineteen (10%) were worse;
- Overall, 90% of patients were either better or no change and 10% were worse.