Cardiac Arrest (Adult)
Mechanism
Chain of Survival
Collapse Summary
MANAGEMENT
Adjuncts
Management points
Aftercare

Mechanism

Sudden primary cardiac arrythmia
VT/VF

Decompensating
Pre-arrest state of shock, resp failure, apnoea, tissue ischaemia, hypoxia.
Often bradicardia, idioventricular rhythms, asystole.
--> either cardiac arrythmia / bradycardia / asystole.
--> or PEA.
Find & treat underlying cause.
Chain of Survival

Early recognition
Early activation of EMS
Early CPR
- bystander action improves survival 2-3x.
Early defibrillation
Early advanced care

- time from arrest to defib is key interval in survival
- success rate declines 5-10% per minute beyond 90s.
- aim for <4min in community, <3 in hospital.
Adult Collapse Summary

Assess
Airway (& C-spine)
Breathing
Circulation
Defibrillate
Drugs
Diagnosis

Leader
Stand back from confusion and direct team.
Ensures defib fast, CPR adequate, ascertains history, resus status.
- note pulse, ABG poor, but end-tidal CO2 useful measures of CPR.
Consults others, info for help.
Asystole for 15m or VF/VT for 30-35m are reasonable points to stop resuscitation efforts.
- but keep going until warm if hypothermic.
Management Plan
ASAP:  Attach defibrillator, assess rhythm.
Adjuncts

Adjunct priorities
Use them as they become available.
1. Defibrillation
2. Advanced airway / ventilation adjuncts
3. Oxygen
- highest possible concentration
- don't connect flowmeters to ET tubes.
- Hudson  mask, don't do less than 4-5L/min else CO2 accumulates.
- Venturi mask for CO2 retainers.
- FIO2 = (FlowX10)-10 between 5-8L/min
- or up to 90% with a reservoir bag.
4. IV Access.
 - fluids in the absence of depletion may increase RAP and decrease systemic blood flow.
- but critical in low volume states.

Advanced Adjuncts

Airway
Suction.

AP/NP airways
Eg guedel - help keep tongue forward.
- check size from ear lobe to corner of jaw.
- 2-3 typical for adults
NP airways better tolerated in partially sedated people, else coughing, gagging, regurge.
- lubricate, insert straight back.
- size 6-7.5 typical

LMAs
Easy, fast, secure airway adjunct but not a longer term solution.
- good for neck injuries.
Inflation pressure of IPPV should be kept to <15mmH20 to prevent stomach distension.
Size 3-4 F and 4-5 M.
Cuff sizes / volumes:
- 1 (neonates) 2-4ml.
- 2 (kids 6.5-15kg) 10ml
- 2.5 (kids 15-30) 15ml
- 3 (30-50kg) 20ml
- 4 (n adults) 30ml
- 5 (>75kg) 40ml.
Technique:
- open airway, lubricate, direct towards hard palate.
- insert until can go no further.
- ensure ventilating adequate
--> if not, open airway, ensure position & inflation, retry.

Combitube
Yet to make an impact.

ET Tube
Protects airway and allows gold standard control.
Better just to bag mask if inexperienced.
- should take <40s, preoxygenate 3mins.
- reoxygenate prior to 2nd attempt.
- if partially conscious, need an anaesthetist
- backward pressure cricoid carilage can help prevent regurgitation.
- backward upward rightward pressure (BURP) doesn't protect airway, but helps visualise cords.
Size 7 for women, 8 for men.
- age/4+4 for children.
- takes 3-8 ml of air to inflate (no more else pressure necrosis)
- teeth at 21-23cm mark, secured.
Confirm location:
- bilateral air entry
- detect expired CO2 (but unreliable in arrest)
- CXR
If in doubt, take it out.
Mechanical ventilation at volume 6-8ml/kg 10 breaths/min.

Persisting obstruction:
Transtrachial Ventilation
Cricothyroidotomy

Drugs
- flush with 10-20ml saline each time.

Adrenaline 1mg/3min
- achieves alpha-mediated peripheral vasoconstriction.
- maintains aortic diastolic blood pressure
- may coarsen fine VF and help defibrillation.
- most effective early in arrest, consider higher doses in refractory arrest.

Vasopressin 40iu
- potent endogenous vasoconstrictor.
- longer and greater effect in hypoxia / acidosis
--> increases cerebral / coronary perfusion.
- in only VF/VT arrests as an alternative to adrenaline
- once only - half life 10-20mins.

Amiodarone 150mg
- complex alpha/beta/ion channel effects.
- use after 3 cycles of shocks / earlier if appropriate.
- repeat after 3-5m.

Atropine 3mg
- anticholinergic - blocks vagal influences.
- asystole / profound bradycardia may result from intense vagal overactivity.
- asystole: 3mg provides permanant blockade - no further doses.
- PEA: atropine 1mg / min, until 3mg.
- bradycardia: 0.6mg IV if symptomatic & sinus.

Aminophylline 250-500mg IV
- unknown effect
- could be considered for refractory asystole; no evidence.

Sodium bicarb
- not routine - increases CO2, worsens respiratory acidosis.
- only indicated in hyperkalaemia, tricyclic overdose, prior metabolic acidosis, and late in cardiac arrest (>10m) in intubated hyperventilated victims.
- flush well - inactivates catecholamines.

Pacing
Indicated in heart block and sinus arrest / sinus bradycardia.
Also can prevent recurrent VT / torsardes.
- most commonly used in resuscitation for complete heart block w brady.
- consider for asystole with p waves (vent standstill)
Conducted in this setting via a transcutaneous pacing device
- painful, so analgesia / sedation
- electrodes in alt. paddle position, stop other ECGs
- rate 70-80/min, synchronous mode, 70mA, increase to max 200mA or until pulse detected.
- reduce to lowest value with palpable pulse and adequate BP.
- if capture but circulation absent --> PEA

Check
Defibillator/ECG source, settings and electrodes
Endotracheal, IV placement
ECG positions
- IEC standard: red (RA) yellow (LA) Green (Foot)
- AAMI standard: white (RA), black (LA), red (LL)


Consider and Correct
Hypotension
Hypovolaemia
Hypo/hyperkalaemia
Hypo/hyperglycaemia
Hypo/hyperthermia
Tension pneumothorax
Toxicity
Thromboembolism
Tachycardia

Management Points

Safety
Eg traffic, electricity, fire, chemicals, poisons, body fluids.
No mouth to mouth if possibility of cyanide, organophsophate, azide or phosphine poisoning.
Usual universal precautions - sputum is lower risk for transmission of disease but barrier devices recommended (not handkerchiefs).

Airway
Open with head tilt, chin lift, jaw thrust
- lifts soft palate, tongue and epiglottus and improves oropharynx intrinsic tone
- if head injury, neutral position & jaw thrust, but airway takes priority
Sweep out foreign material from mouth with a finger sweep
- only if pt unconscious
- not the deeper stuff as risk of pushing it down further.

Assess Breathing / Circulation
Slow gasping resps after arrest are inneffective
- and movement of chest / abdo is not necessarily reassuring
- listen and feel for air escaping.
Don't just feel carotid, do a 'circulation check'
- seek carotid pulse in groove between larynx and sternomastoid.
- and look at colour, movement breathing.

--> Adequate breathing / circulation
Recovery position.


--> Apnoea but circulation
Ten expired breaths over one minute
Then reassess breathing / circulation.

--> Inadequate breaths but circulation
Assist ventilation over one minute
Then reassess.

--> Chest moving but no Air flow
Open airway

--> Breathing absent or no circulation
As for adult cardiac arrest.

Precordial Thump
Delivered to mid-sternum from 20cm with ulnar side of closed fist.
Causes depolarisation, reverting 2% VF and 10-25% VT.
Could also cause sinus rhythm to change to VF if on a T wave (R on T).
Only if:
- witnessed arrest.
- within 2 mins.
- no CPR already given.
- no pulse.
- no defibrillatory available.
If transiently successful, can repeat for up to 30s at 60-80/min, then give up.

Going for Help
If alone
and you will be longer than 4mins to return to pt
and there is no possibility of getting defib to scene <20mins
--> Given CPR for 2mins
--> Then go for help.

Rescue Breathing
Expired F02 is approx 0.16.
Can produce PaO2 of 70-75mmHg (90% normal).
Mouth to mouth equivalent to mouth to nose.

Technique
Each breath makes chest rise (400-600ml), each 2s.
- any more may inflate stomach (opening pressure 20-22cmH20)
- this increases regurge / aspiration risk and splints diaphragm.
- do not force air back out.
- if regurge occurs, tip into recovery posn, clear airway.
Try to get two good breaths at first attempt (have 5 efforts).
Use mouth to nose when mouth to mouth not possible.
- or in children <1 (or mouth to nose-and-mouth).

Chest Compressions
Works initially by direct compression on heart.
Later heart becomes floppy and changes in thoracic pressure drive output.
May achieve systolic BP 60-80 palpable at carotids.
Diastolic pressure seldom exceeds 40 (reqd level for coronary perfusion).
- coronary flow only occurs during diastole.
- thus myocardial ischaemia is inevitible, though brain may be ok.
- adrenaline / vasopressin increase diastolic BP.

Technique
Firm surface.
 - bed board to lift to floor.
Either two fingers above xiphisternum
or at jx of middle/lower thirds of sternum.
Press firmly moving from hip, arms locked, weight over heart.
- depress sternum 4-5cm (depth critical).
- a sinusoidal flow
- rate 100/min adults & children.
- ratio of 2 breaths : 15 compressions.

Defibrillation
Indicated in VF/VT.
Simultaneously depolarises the myocardial fibres.
Ideal within 90s of onset, preferably within 8mins.

Technique
Apply gel or pads, wipe away excess.
Turn on defibrillator.
Charge paddles upon placement on chest.
Place just to R of upper sternum, below clavicle, and just to left of apex with gel/pads.
- Remove metal, >12.5cm clear of pacemaker.
- Could change to left of left lower sternal border and inf to left scapula if unsuccessful.
Derive ECG rhythm from paddles.
- If not sure of rhythm, check leads are correctly placed.
- Turn gain up - must be >1mV for VF.
- If unsure, shock.
Shock delivering ~25lb weight on chest.
- say 'stand back' & don't touch.

If VF/VT persists
Spend next minute doing CPR then retry.
Place ECG electrodes on chest.
Perform adjunctive manoeuvres.

AEDs
Automatic, useful for untrained users.
Turn it on and follow orders.
If not shockable, check pulse and rhythm carefully.
Not used in kids.

Monophasic vs Biphasic
Monophasic: voltage rises rapidly, then returns to baseline either fast or damped.
Biphasic: sinusoidal
- most are monophasic.
- biphasic require less energy for same effect - can be smaller, cheaper and less damaging.

Synchronised Cardioversion
Shocking on a T wave can precipitate VF/VT in systolic pt.
Hence safer to synchronise to R wave.
- most pts are conscious and need sedation
- fire and keep paddles pressed until QRS established by machine.
AF - use 100-200J
SVT - use 50-100J
AFlutter - use 50-100J
VT (monomorphic) - 100J
VT (polymorphic) - 200J

Other rhythms
Don't shock asystole.
Ventricular standstill (p waves w/out qrs) can be treated with transcutaneous pacing.

Theoretical Points
Transmyocardial current determined by energy (J) and resistance of chest walls (Ohms).
- average impedence is 70-80Ohms.
200 J is used as has same efficacy as higher doses.
- initial shock reduces impedance to flow across chest, so second shock also at 200J is more powerful.
After Care

If appropriate:
Secure airway.
Inadequate breathing indicated by:
- tracheal tug, see-saw chest movements, RR>30, falling sats, rising PCO2.
Check ET tube position.
 - sedation with low dose propofol / morphie/midaz as appropriate.
Highest possible conc O2.
Consider indwelling arterial catheter.
Transfer to ICU/CCU
- period of elective ventilation often advisable for prolonged arrests >3m.
- continuous monitoring of sats, heart rhythm, BP, urine output, ETCO2 output.
- want PaO2 at 100 and PaCO2 at 35-40.
- nasogastric tube to decompress stomach.

Establish aetiology.
History
Physical exam
- note also for complications of resuscitation.
- check fluid status and correct.
CXR, ECG, bloods, ABG, BSL.

Acute Hypoxic Brain Injury
Consider if decreased LOC persists beyond a few minutes after restoration of circulation.
Accurate prognosis cannot be given immediately.
Motor response at day 2-3 is best early prognostic indicator.
- persisting (>30m) myoclonic activity is a poor indicator
- early pupillary findings / eye opening unreliable.
- EEG usefulness varies
- CT is often normal even after significant infarction - not indicated.
Carefully control PO2 and PCO2 to normal.
Aim for MAP 80-100 mmHg with fluids / inotrope infusions.
Maintain Hb above 100.
Maintain electrolytes, acid-base, osmolality and glucose levels.
Avoid T >38.5, slight hypothermia to 35 is permissable.