ALS book Flashcards
What are the two biggest single causes of death in the UK?
- Dementia
- Ischaemic heart disease
The average survival to discharge from in-hospital cardiac arrest was slightly less than 24%.
The average survival to discharge from out of hospital cardiac arrest is around 10%
Around half of cardiac arrest are witnessed by either a bystander or ambulance staff. How common are the four different presenting rhythms for out of hospital cardiac arrest?
OUT OF HOSPITAL CARDIAC ARREST
Shockable (ventricular fibrillation and pulseless ventricular tachycardia) account for a quarter of cases
Non shockable the remainder of cases - asystole in about 50% and pulseless electrical activity in about 25%
In hospital is difficult to accurately assess due to other factors eg people have DNA CPRs
Defibrillation within 3-5 min of collapse can produce survival rates as high as 50-70%. Each minute of delay to debrillation reduces the probability of survival to hospital discharge by 10-12%.
When should you start CPR?
When do you attempt defibrillation?
Which drugs are given in both shockable and non-shockable rhythms?
Start CPR if unresponsive and not breathing normally in a 30 compression to 2 rescue breaths format
Attempt defibrillation if shockable (VF / pulseless VT) - shock as soon as you know this is the rhythm and repeat rhythm check +/- shock every 2 minutes
Shockable - give adrenaline every 3-5 mins (initial dose after 3 rd shock and then at every other shock), give amiodarone after 3 shocks
Non-shockable - give adrenaline every 3-5 mins
Whagt is the usual current for a shock in a patient?
How long should the puase in chest compressions to confirm the rhythm last?
120-150Joules (in reality shock can range anywehere between 120 and 360 Joules) for first shock and the same or higher for consecutive shocks
Pause in the chest compression - should aim for less than 5 seconds
As stated, give adrenaline every 3-5 mins or every rhythm check/shock
What is the dose of adrenaline given in adults?
Would you give a second dose of amiodarone in shockable rhythms? If so, what dose?
1mg IV adrenaline given every 3-5 minutes in both shockable/non-shockable
Amiodraone - given 300mg IV after 3 shock attempts, consider a further 150mg IV after 5 shocks if remaining in pulseless VT/VF
How does adrenaline work to help in cardiac arrrest?
How does amiodarone work to help in cardiac arrrest?
Adrenaline - increased myocardial force of contraction (positive inotrope) and heart rate (positive chronotrope) occur as a result of β1 receptor stimulation. Systemic vascular resistance is increased overall because the stimulation of α1 receptors results in peripheral vasoconstriction, which counters the vasodilation due to β2 receptor activation
Amiodarone - blocks potassium currents that cause repolarization of the heart muscle during the third phase of the cardiac action potential. As a result amiodarone increases the duration of the action potential as well as the effective refractory period for cardiac cells (myocytes).
What are the four Hs and four Ts that are reversible causes of cardiac arrest?
Hypoxia
Hypovalaemia
Hypo-hyperkalaemia / metabolic acidosis
Hypo/hyperthermia
Thrombosis - coronary or pulmonary
Tension pneumothorax
Tamponade - cardiac - need a focussed cardiac ultrasound to exclude held in sub-xiphotic space (also helps detect aortic dissections and pneumothorax)
Toxins
Whats do you do once you achieve ROSC?
Aim for SpO2 of 94-98% and normal PaCO2
12-lead ECG
Identify and treat cause
Targeted temperature management
What is the frequency of monitoring for different NEWS scores:
- 0
- 1-4
- 3 in single parameter
- 5or6 (urgent response threshold)
- 7or more (emergency response threshold)
- 0 - minimum 12 hourly monitoring
- 1-4 - minmum 4-6 hourly monitoring (registered nurse must be informed, can decide if it requirres increased monitoring / escalation)
- 3 in a single parameter - minmum 1 hourly - (medical team to be informed and should review, can decide on escalation)
- 5or6 - medical team to be informed and can decide on escalation
- 7or more - medical team to be informed, at least specialist registrar level , consider HDU or ICU
Medical emergenecy team criteria discuss different reasons to call.
WHat are they? (can split into the different parts of the ABCDE)
- Airway - threatened
- Breathing - all resp arrests, resp rate <5/min or >36/min
- Carciulation - all cardiac arrests, 40>HR<140 or SBP <90
- Disability/neurology - sudden decrease in level of consciousness, decrease in GCS of >2 ppoints, repeated/prolonged seizures
- Exposure - any patient causing concern who does not fit above criteria
Use the ABCDE approach to assess and treat the deteriorating or critically ill patient. Do a complete initial assessment and re-assess regularly. Call for appropriate help early and use all members of the team.
How long should the initial look, listen and feel take?
The initial look listen and feel should take no longer than 10 seconds in a patient who is unresponsive and will often indicate if the patient is critically ill
You can feel for a pulse to check if it is solely a repsiratory arrest -
What does surgical emphysema or cepitus in the chest wall suggest until proven otherwise?
A pneumothorax (obviously can also get it with Boerhaave’s)
What coould suggest hypovalaemia on quick assessment of the unwell patient?
How do you measure capillary refill time?
What does prolonged CRT suggest? What can affect it?
Hands/digits - are they blue/pink/pale/mottled. Are they cool or warm.
CRT - apply cutaneous pressure for 5s with enough pressure to cause blanching - press on sternum for central CRT or on a finger tip at hear level for peripheral |CRT
Normal is <2 seconds.
Proloned suggest poor perfusion. Cold surroundings, poor light and old age can prolong CRT
What are the KDIGO stages of acute kidney injury? (describe bopth serum creatinine and urine output)
Ooliguira is a sign of low cardiac output
If there are symptoms and signs of cardiac failure - dyspnoea, increased heart rate, raised JVP, a third heart sound and pulmonary crackles on auscultation, how should you change your fluid management of the acutely unwell patient?
Decrease fluid infusion rate or stop the fluid altogether - seek alternative means of improving tissue perfusion eg inotropes or vasopressors
During the acute phase of STEMI, there is a substantial risk of ventricular tachycardia , ventricular fibrillation and sudden death.
Do not wait for confirmation of elevated troponin to make initialy diagnosis if ECG and symptoms are suggestive.
What is the inital treatment if suspecting a STEMI in GGC?
Morphine IV 10mg +Metoclopramide IV 10mg Oxygen if O2 <94%, GTN spray 2 puffs sublingual, Aspirin 300mg oral, Tricagrelor 180mg oral
+/- fondaprinux 2.5mg SC (or heparin IV 5000units)
What are the two cardiac specific tropnonins? What is the other troponin?
- There is Troponin C - calcium binding site (pulls troponin tropmyosin complex apart exposing actin filaments for actin-myosin cross bridge linking) - identical in heart and skeletal muscle
- TROPNIN I (inhibits actin-myosin interactions) and
- TROPONIN T (facilitates contraction) are the cardiac specific troponin isoforms
What on an echo could indiccate the likelihood of an ACS?
Echo - left ventircular systolic function is directly related to prognosis. IN patient with acute chest pain - regional wall motion abnormalities increases the likelihood of ACS - but are not diagnostic
Adenosine-diphosphate (ADP) receptor antagonists (aka P2Y12 receptor antagonists) are drugs which prevent the aggregation (‘clumping’) of platelets and consequently reduce the formation of blood clots.
They include clopidogrel, prasgruel and ticagrelor
If considering PPCI for STEMI, one of the above should be given in addition to 300mg aspirin. What are the doses of the above drugs?
Clopidogrel - should be 600mg
Prasgruel 60mg (if not >75 years or <60kg, history of bleeding or stroke)
Ticagrelor 180mg
For patients presenting with STEMI, within 12 h of symptoms onset, mechanical (eg PCI) or pharmacological (thrombolysis) reperfusion must be achieved without delay
What is the preferred method revasuclarisation and when can it be carried out? What is the alternative?
Preferred method revascularisation is primary PCI with angiographic identification
* Should be offered to all patients who present within 12 hours of symptoms onset and who can be transferred to a primary PCI centre within 120 minutes of STEMI diagnosis
* If patient presents within 12 hours and cannot be transferred to a primary PCI centre within 120 minutes of diagnosis, they should recieve thrombolysis
In patients who cannot make the PCI, and are given thrombolysis instead, when shold you re-record a 12-lead ECG to check for resolution of ST segment elevation?
What do you do if they havent resovled?
Re-check ECG in 60-90 minutes
If successful, still transfer to CCU if not alreay
If unsuccessful, transfer immediately to cardiac cath lab for coronary angiography + PCI - rescue PCI
What is the rhythym that is seen commonly and transiently after reperfusion of a previously occluded coronary artery?
This is an accelrated idioventricular rhythm - usually transient, no haemodynamic compromise caused and require no treatment
In some people, cardiac arrest in VF or pVT may be the presenting feature of ACS. If return of ROSC is achieved, record a 12 lead ECG as soon as possible. If this shows evidence of STEMI, emergency re-perfusion may be needed.
- If a ventricular arrythmia occurs within 24-48 hours of a confirmed ACS, would an implanatable cardioverter-defibrillator be indicated?
- If a sustained ventricular arrythmia occurs more than 24-48 hours of a confirmed ACS, would an implanatable cardioverter-defibrillator be indicated?
- Within 24-48 hours of ACS - ICD is not indicated for a ventircular arrythmia unless the patient has peristently severely impaired LV function for at least 4 weeks post ACS
- Sustained ventricular arrythmia occuring more than 24-48 hours after an ACS - ICD is usually recommended unless the arrythmia was associated with signifcant myocardial sichaemia which can be reverse without vascularisation
if the ventricular arrythmia occurs without evidence of severe ischaemia, refer to heart rhythm specialist as they will be at risk of recurrent ventricular arrythmia and need be assessed for insertion of ICD priore to discharge
If AV block occurs in the context of an inferior acute myocardial infection, there is often transient dysfunction of conducting system and excessive vagal activity. How would symptomatic bradycardia be treated?
Treat with atropine
If resistant to atropine, can try temporary cardiac pacing (permanent not usually needed)
What should be given for symptomatic management of heart failure complication AMI or other ACS?
Give a loop diuretic eg furosmide and/or GTN spray for immediate symptomatic relief then continue maintenance loop diuretic.
Give the other secondary prevention drugs (Statin, aspirin, beta blocker, ace +/- secondary anti-thrombotic)
If LVSD <40%, aldosterone receptor antagonist
If an in-hospital cardiac arrest takes place. How soon should defibrillation be attempted if indicated?
Attempt defirbillation within 3 minutes
Where is the best location for CPR? How deep are compressions and at what rate?
What rate are rescue breaths given once tracheal intubation has been succeeded?
Middle of lower half of the sternum
Depth of 5-6cm
Rate of 100-120 compressions /min (30compressions to 2 rescue breaths)
Rescue breaths given at 10 breaths per minute once the trachea has been intubated
If the patient has a monitored and witnessed cardiac arrest in the cath lab, CCU or cirticcal area area or whilst monitored after cardiac surgery and a manual defibrillator is rapidly available, you can give stacked shocks if in a shockable rhythm.
How many shocks is this?
Do you do CPR between shocks?
What do you do after these shocks if still in arrest?
What do these three shocks count as in the ALS algorithm?
- If a monitored and witness cardiac arrest with a manual defibrillator available, you can give three quick successive (stacked shocks). Rapdily check for a rhythm change and if appropriate pulse or other signs of ROSC after each attempt
- Do not do CPR between attempts
- If still in arrest, start CPR for 2 minutes as per ALS algorithm
- The three shocks are considere as giving the first shock in the ALS algorithm
When would you give adrenaline / amiodarone after stacked shocks?
Three stacked shocks counts as first initial shock in ALS algorithm - give adrenaline after 3rd shock in ALS algorithm
Amiodraone is given after three shock attempts irrespective of when they are given during the cardiac arrest - ie give amioraone during the 2 min of CPR after the three stacked-shock attemps
If the three stacked shocks have been given in the post cardiac srgery setting, what should then be prepared for as you conitnue CPR?
Emergency resternotomy should be prepated for
When would you ever consider a precordial thump?
Very low success rates and therefore routine use is not recommended
A precordial thump rarely works and must not delay calling for help or accessing a defibrillator.
Consider only when it can be used without delay whilst awaiting the arrival of a defibrillator in a monitored VF/pVT arrest
Use ulnar edge of tightly clenched fist to delvier sharp impact to lower have of the sternum from approx height of 20cm then retract fist immediately - creats impulse like stimulus
Whcih is more important for contributing to improved survival after cardiac arrest
Prompt and effective bystander CPR, uninterrupted high quality chest compressions and early defib for VF/pVT
or
drugs and advanced airways?
Prompt and effective bystander CPR, uninterrupted high quality chest compressions and early defib for VF/pVT are the most important
Where on the body are the defib pads placed?
One below the right clavicle and the other in the V6 position, midaxillary line on the left side
After the intiial check for signs of life prior to initial defibrillation, when should you next manually check for signs life? (if signs of ROSC, start post-resuscitation care)
After giving the 3rd shock in shockable rhythm continue immediately CPR for 2 mins before next pulse check
Check for a pulse in non-shockable rhythm if changes on the ECG show a rhythm compatible with life or if symptoms of ROSC
Describe fully what you would do in shockable rhythm?
ALS Algorithm shockable
* Once defib ready, immeidately give shock then immediate CPR for 2 mins before re-checking
* If remaining in VF/pVT, continue shocks every 2 minutes
* After 3rd shock, give 1mg IV adrenaline (1:10,000) and amiodarone 300mg IV
* Give further 1mg IV adrenaline every 3-5 minutes (alternate cycles)
* A further 150mg of IV amiodarone may be given after a total of 5 defibrillation attempts
What is an alternative to amiodarone for shockable rhythms?
- Lidocaine 100 mg IV (IO) may be used as an alternative if amiodarone is not available or a local decision has been made to use lidocaine instead of amiodarone.
- An additional bolus of lidocaine 50 mg can also be given after five defibrillation attempts.
Describe fully what you would do in non-schockable rhythm?
- Give 1mg IV adrenaline (1:10,000 = 1g in 10,000ml, = 1000mg in 10,000ml = 1mg in 10ml) as soon as IV access achieved
- Re-check the rhythm every 2 minutes - if electrical activity compatible with a pulse, check for pulse and/or signs of life. If neither conitnue CPR and reheck rhythm every 2 minutes again
- Give further 1mg IV adrenaline every 3-5 minutes (alternate cycles)
What must drugs injected peripherally be followed with?
Must be followed with at least 20ml of fluid and elevation fo the extemrity for 10-20seconds to facilitate delivery to the central circulation - can hang up a 500ml bag of saline during arrest to provide this
Even if the defibrillation attempt is successful in restoring a perfusing rhythm, it is very rare for a pulse to be palpapble immediately after defib, how long can it take?
Return of a palpable pulse may be longer than 2 min in as many as 25% of successful shocks
- Delay in trying to palpate a pulse with further compromise the myocardium if a perfusing rhythm has not beenr estored
- If a perfusing rhythm has been restored, giving chest compressions does not increase chance of VF re-occuring
Important in shock-refractory VF/pVT to check position and contact of defib pads.
How long is it usually considered worthwhile continuing resuscitation for?
Usually as long as the patient remains in identifiable Vf/pVT. Generally accepted asystole for more than 20 minutes in the absence of a reversible cause constitutes grounds for stopping
Can consider changing pad position in refractory VF/pVT from anterior-lateral to anterior-posterior
If a rhythm that is compatible with life shows, try to palpate for central pulse and look for other evidence of ROSC. What is other evidence of ROSC?
What is the normal end tidal CO2 range?
ROSC - sudden increase in end-tidal CO2 (normal range is 4.3-5.5 - normal is 4.8)
Evidence of cardiac output
Any invasive monitring rquipment
When the normal end tidal CO2 is seen or when a patient starts displaying signs of life, chest compressions should be paused and patient should be reassessed.
If during CPR, the underlying rhythm on the monitor displays VF, should you attempt defib at this stage?
If the monitor displays VF int he middle of a CPR 2 min cycle, continue CPR until the 2 minute rhythm check period
Continue 30:2 chest compressions until the airway is secured.
What is the ideal method of securing the airway?
What can be used in the absence of personal skilled in this method?
Ideal method is using a cuffed endotracheal tube
In the absence of this, a bag mask or preferably, a supraglotttic ariway (SGA) eg i-gel is used.
Can now attempt to devler continuous chest compressions, uninterrupted during ventilation - 10 breaths / min
Waveform capnography during PCR has an important role.
Which airway tube does it work most reliably with and who can it be used with ?
WHat is its role?
Works most reliably in patients with a tracheal tube - can be sued wtih supraglottic airway device or bag mask
Role- ensures travheal tube placement in trachea, monitoring ventilation during CPR, quality of chest compressions, idnetifying rosc, prongosis (lower end-tidal volume has increasied mortality)
What is the normal end-tidal CO2?
How would you help clarif that the tracheal tube is situated correctly?
Normal - 4.3-5.5 (normal is 4.8kPa)
Observation and auscultation to ensure both lungs are ventiliating and eg tube hasnt passed into a bronchus
If rapid IV access if difficult or imporrible, consider IO route. WHat are the three main sites for access?
WHat are contraindications?
Sites - proximal humerus, proximal tibia and distal tibia
Contraindication - truma, infection or a prosthesis at target site, recent IO access within prev 48 hours in same limp incl failed attmept - failure to identify landmarks
Again, state the 4Hs and 4Ts
Hypoxia
Hypovalaemia - may not be obvious eg GI bleeding or ruptured AAA
Hypo/hyperkalaemia, hypoglycamiea, metabolic disorder
Hypo/hyperthermia
Thrombosis - conroary or pulmonary
Tensions pneumothorax
Tamponade
Toxins
If a fibrinolytic drug is given during CPR for a suspected PE, how long should you consider preforming CPR for before stopping?
Consider CPR for 60-90 minutes
How long should you observe the patient after stopping CPR before confirming death?
Minimum of 5 minutes
What is the commonest site of airway obstruction?
What is the comonest in trauma?
Commonest site of airway obstruction is the soft palate and epiglottis rather than the tongue
The commonest cause of airway obstruction in trauma is the loss of pharyngeal tone with posterior tongue displacement
Complete airway obstructin - often see paradoxical chest and abdo movements - known as see-saw breathing
In partial airway obstruction, air entry is diminsihed and usually nosy
Where do the following noises heard suggest the obstruction is occurrign:
- Inspiratory stridor
- Expiratory wheeze
- Gurgling
- Snoring
- Inspiratory stridor - laryngeal level or above
- Expiratory wheeze - lower airways which tend to collapse and obstruct during expiration
- Gurgling - presence of liquid or semisolid foreign material in upper airways
- Snoring - arises when pharynx is partially occluded by the gonue or palate
What are signs of severe airway obstruction and what should you do?
Pt unable to speak, can only respond by nodding, unable to breathe, breathing sounds wheezy, attempts at coughing are silent, may be unconscious
Give 5 back blows - between scapula with heel of hand
Give 5 abdominal thrusts
Continue to alternate if no success
If becomes unconscious, call arrest team and start CPR
How would you attempt to remove a foreign body in a chocking unconscious patient?
If back blows/abdo thrusts failed, start CPR
ONce a trained pro arrives, use laryngoscopy + Magill’s forceps
There are basic airway manoevures as well as airway technique for herlping to increase oxygenation. Artificial ventilation is started as soon as possible in patients whom spontenous ventilation is inadequate or asbent.
If a self-inflation bag (non rebreather, resevoir bag) is attached directly to high fllow oxygen as well as a reservoir system, what is the percentage of inspired oxygen?
Approx 85%
In comparison with bag-mask ventilation, use of SGAs (supraglottic airways) may enable more effective ventilation and reduce the risk of gastric inflation (reduces risk of regurgitation and pulmonary aspiratiomn)
Try to maintain chest compressions throighout. If it is necessary to stop, how long should this pause take?
What size will suit most adults?
What should you do before inserting the igel?
If it is necessary tos top to insert the i-gel, limit the pause to compression to max 5s
Size 4 will suit most adults
Before inserting - lubricate the front, back and sides
What position should the patient be for igel insertion?
Sniffing the mornig air position - neck flexed and head extended
How do you know how deep to insert the i-gel?
Should feel a defintive resistance on insertion - at this point the tip of the airway should be loacted at uppe roseophageal opening and cuff should be klocated against the larynx
- the incisors should be resting on the integral bite-block - where a horizontal line is present as a guide
What does expert consensus define the skill threshold for tracheal tube insertion?
How do you confirm placement of tracheal tube?
95% success rates with up to two intubation attempts
Confirm placement with both clinical assessment (observation/auscutation of lungs, auscultate over epigastric area also - should not hear breath sounds) and waveform capnography - studies show this is both 100% sensitive and 100% specific for correctly placed cuffed endotracheal tube
What does failure to detect any exhaled CO2 by the waveform capnography suggest?
This would suggest the tube is in the oesophagus - No trace - Wrong Place
If a person’s ECG displays VF requiring immediate defib and they are conscious or have a pulse, is it VFib?
No the rhythm must be artefact
Which rhthm displays capture and fusion beats?
How do these occur?
This would be monomorphic VT
Atrial activity may continue independently of ventricular activity leading to caputr and fusion beats
Capture beat- single normal looking QRS without interrupting the arrythmia
Fusion beat - wave of depolarisation from AV node occurs at the same time as a wave of depolarisation travelling up from ventricle causing a hybdrid QRS
Rhythms that can mimic VF include polymorphic VT and AFib with abberancy
* Atrial fibrillation in the presence of either bundle branch block or pre-excitation (accessory pathway) will result in an irregular wide complex tachycardia
It is important to identify polymorphic VT. How are these patients treated?
What is this rhythm also known as?
Poolymorphic VT eg Torsades de Pointes
Treated with IV magnesium 2g over 10 minutes
May also require potassium as many patients are hypokalaemia and/or hypomagnaesamic
Peri-arrest arrythmias are defined according to heart rate - bradyarrythmia, tachyarrythmia or arrythmia with a normal heart rate.
What is bradyarrythmia defined as? When can it be considered physiological?
What is the emergency treatment?
Bradyarrythmia is defined as resting heart rate of <60 / min
Can be physiological in athletes or during sleep
If associated with life threatneing signs - atropine 500mcg IV and /or cardiac pacing
Peri-arrest arrythmias include bradyarrythmia, tachyarryhmia, Aflutter/Afib, Heart block
Describe the different types of heart block
- 1st degree heart block - PR interval consistently >0.2 seconds
- Mobitz type I AV block (aka second degree aka Wenckebach) - progressive prolongation of PR interval until a p-wave occurs without a resulting QRS complex
- Mobitz type 2 AV block - constant PR interval (often prolonged) but some p-waves are not followed by QRS complexes - can occur randomly without any consistent pattern
- Third degree AV block (aka complete heart block) - no relationship between p-waves and QRS complexes - atrial and ventircular depolarisation arising from separate pacemakers
- 1st degree heart block - PR interval consistently >0.2 seconds
- Mobitz type I AV block (aka second degree aka Wenckebach) - progressive prolongation of PR interval until a p-wave occurs without a resulting QRS complex
- Mobitz type 2 AV block - constant PR interval (often prolonged) but some p-waves are not followed by QRS complexes - can occur randomly without any consistent pattern
- Third degree AV block (aka complete heart block) - no relationship between p-waves and QRS complexes - atrial and ventircular depolarisation arising from separate pacemakers
Which require treamtnet?
Which are at danger of progressing to complete heartblock>
1st degree - rarely causes any symptoms and rarely requires treatment
Mobitz type 1- need for treatment determined by effect of the bradyarrythmia
Mobitz type 2 - always pathological, requires treatment and at risk of progression to complete heart block and asystole
Complete heart block - may require immediate treatment
What is an agonal rhythm?
Agonal rhythm occurs in dying patients. Slow irregular wide ventricular complexes - doesnt usually generate a palpable pulse - usually seen in latter stages of unsuccessful resuscitation attempts
Narrow complex tachycardias arise above the bundle of HIS - termed supraventircular.
Where can broad complex tachycardias originate?
A tachyardia arising in the ventricle
or
A supraventricular tachycardia conducted abberantly (right or left bundle branch block) to the ventricles
What is the safest approach for treating all broad complex tachycardias as?
Treat all broad complex tachycardias as ventricular tachycardia unless there is good evidence to suggest it is supraventricular in origin
Why is a QTc >0.5 seconds worrying?
What is the target QTc in men and women?
QTc>0.5seconds indicates a high risk of cardiac arrest and sudden death. Prolongation predisposes to ventricular arrythmia, in particular TdP and VF
QTc men <0.44, QTc women <0.46
How far away should the defib electrodes be placed away from an implnatable medical device?
At least 10-15cm away from the device
What is successful defibrillation defined as?
Successfull defibrillation is defined as the absecne of VF/pVT at 5s after shock delivery
Remember to keep immediate CPR post-shock delivery until the post-shock circulation is established (the duration of asystole before ROSC can be longer than 2 min in as many as 25% of successful shocks)
In an oxygen-enriched atmosphere, sparking from poorly applied defibrillator paddles can cause a fire and significant burns to the patient. The use of the self-adhesive electrodes if far less likely to cause sparks than manual paddles.
What is good practice for safe use of oxgen during defibrillation
When it comes to oxygen mask/nasal cannulae?
When it comes to ventilation bag connected to a tracheal tube or supraglottic away?
Oxygen mask/nasal cannulae - remove and take at least 1m away from patient
Leave the ventilation bag connected to tracheal tube or supraglottic airway device - no increase in O2 occurs in the zone of defib as this is a sealed circuti
Alternatively, can disconnect the ventilation bag from the tube/SGA device and remove it at least 1m from the patients chest during def
What is the difference between synchronous and asynchronous chest compressions?
Which is preferred?
During cardiopulmonary resuscitation (CPR), the need to interrupt chest compressions to provide synchronous ventilations prevents blood flow continuity, reducing the possibility to ensure high-quality CPR bundles of care and, thus, having a potentially negative impact on perfusion and patient outcome.
a strategy of continuous compressions with “asynchronous” ventilations during CPR in patients with an advanced airway, that is, breaths interposed every six seconds without interruption in CPR—OR 10 breaths/minute without stopping CPR - this can hopefully prevent the negative effects of stopping for synchronous ventilation
In the community, automated external defibrillation (AEDs) are used to carry out defibrillation
Are AEDs or mannual defib preferred in hospital and why?
In hospitals, where there is rapid access to manual defibs and trained staff are present, use a manual defib- they enable the operator to diagnose the ryhthm and deliver a shock rapidly without having to wait for rhythm anyalysis and this minimises the interruption in chest compressions
Is defibrillation in cardiac arrest asynchronous or synchronous?
When would you use the other?
Defibrillation in cardiac arrest uses asynchronous cardioverison
Defibrillation or unsynchronized cardioversion is indicated in any patient with pulseless VT/VF or unstable polymorphic VT, where synchronized cardioversion is not possible.
Synchronized cardioversion is utilized for the treatment of persistent unstable tachyarrhythmia (atrial or ventricular) in patients without loss of pulse
Why is synchronised cardioverson important in atrial/ventricular cardioverson? WHat is the shock syncrhonised with?
Can it be carried out when the patient is conscious?
It is important to carry out synchronous cardioversion with the R wave of the ECG - by avoiding the relative refractory period in this way, the risk of inducing VF is minmised
Conscious patients must be anaesthetised or sedated prior to attmepting synchronise cardioversion
What is the difference between absolute refractory period and relative refractory period?
During the absolute refractory period, a second stimulus (no matter how strong) will not excite the neuron. During the relative refractory period, a stronger than normal stimulus is needed to elicit neuronal excitation.
Therefore cardioversion in the RRP could cause Vfib - hence avoided by syncing with R waves
Most manual defibs incorporate a switch that enables the shock to be triggered by the R wave on the electrocardiogram- the operator should anticipate the slight delay between pressing the buttons and the discharge of the hshock when the next r wave occurs
If the patient has an implanted electronic device, choose the position for the defibrillator electrode placement carefully. Usually cardiac pacemakers and Implantable cardioverter-defibrilators are implanted in the pectoral region, more commonly on the left side rather than the right side
An implantable ICD gives no warning when delivering a shock
WHat dose will be discharge from an ICD when detecting a shockable rhythm?
ICD will discharge approximately 40J (approximately 80J for subcutaneous devices) through an internal pacing wire embedded in the right ventricle - will often fire up to 8 shocks