College Answer

a)  How will you respond to this crisis?

•    Confirm cardiac arrest
•    Good BLS i.e.:
•    Check  ETT  position  (pull  back  to  22cm),  listen  to  chest  and  confirm  ETCO2 trace(10)
Check adequate  CPR: correct  position  (lower half of sternum),  correct rate/depth
and  technique  (depress  4-5cm  at  100/min  and  asynchronous   ventilation  with respiratory  rate 8-10)

Call for additional help
•    Confirm IV access
•    Continue CPR for 2 min
•     Adrenaline

b)  You suspect  cardiac tamponade.  Describe  how you would perform blind pericardiocentesis.

•    Some asepsis
•    Identify  landmarks:  Left  paraxiphoid  (traditional)  Left  parasternal  (4th   intercostal space left parasternal)
•    For a left paraxiphoid approach 45° to the abdominal wall, head for the left shoulder, aspirate as you go
•    Could connect  a V lead to the base of the needle  and watch ECG to look for a change  in  the  QRS  morphology,   or  ST  elevation  if  the  needle  contacts  the myocardium
•    Aspirate fluid/blood
•    Consider placing a catheter/pigtail
•    Blood stained pericardial fluid will not clot whereas intraventricular blood will

c)  What  clinical  signs  might  have  indicated  pericardial  tamponade  as  the cause prior to the arrest?

Distended neck veins

Muffled heart sounds

Hypotension

Tachycardia
Pulsus paradoxus

Absent apex beat

ECG findings – low voltage complexes and electrical alternans

Discussion

The scenario presented to us is that of a PEA arrest. In questions which ask "how would YOU respond to this crisis" the college is probably looking for a systematic approach.

Thus:

1) Confirm cardiac arrest

2) Call for help

3) Commence BSL (CPR) until help arrives;

• 100 compressions per minute
• Compression to a depth of 1/3rd of the anterior-posterior chest diamweter
• Asynchronois ventilation of 8-10 breaths per minute
• Ensure the ETT is not malpositioned (chest examination, end tidal CO₂ or calorimetry)

4) With help arriving, follow the non-shockable pathway of the ALS algorithm, which consists of CPR and 1mg adrenaline every 2nd cycle.

4) Work on resolving the cause of the arrest, using the "four Hs and four Ts" as a general guide

Confirm cardiac arrest? According to the AHA, "Cardiac arrest is the cessation of cardiac mechanical activity as confirmed by the absence of signs of circulation". One might struggle looking for signs of circulation. The Australian Resuscitation Council recognises the fact that people are unequal in their ability to detect a pulse, and recommends that "if the victim is not responsive, the airway should be cleared and breathing assessed, and if the victim is not breathing normally, CPR should be commenced..." According to them, "it is reasonable that [rescuers] use the combination of unresponsiveness and absent or abnormal breathing to identify cardiac arrest".

Blind emergency pericardiocentesis is probably an artefact of a bygone era, and many would argue that these days it is not defensible, given the time it takes to find and set up the kit is probably enough time for a runner to return with an ultrasound machine.

However, if caught in such a situation, one would perform the following steps:

• Raise the head of the bed 45° if the situation permits (this one does not)
• Antibacterial prep and drape
• Palpate the xiphisternum and ribs: that is your landmark.
• There are three main approaches:
  • Subxiphoid approach: Insert needle just under the xiphoid, and advance in the direction of the left shoulder while aspirating.
  • Parasternal approach: Insert the needle perpendicular to the chest wall in the fifth intercostal space, just lateral to the sternum.
  • Apical approach: insert the needle in the intercostal space below and 1 cm lateral to the apex beat, aimed toward the right shoulder. One can easily skewer the ventricles in this way. It is not for the faint of heart (pun).
• Withdraw fluid until cardiac output improves
• Advance guidewire and dilate over it.
• Advance pigtail catheter over guidewire, and suture in place

Other methods are available (ultrasound-guided and ECG-guided approaches) but these are not strictly speaking "blind".

As for the signs of cardiac tamponade - these are universally recognised as "Beck's Triad":

• Raised JVP / distended neck veins
• Muffled heart sounds
• Hypotension

It is also universally acknowledged that these features are observed only in a minority of patients. Other, more common features include the following:

• Pulsus paradoxus
• Increased stroke volume variation (art line "swing")
• Decreased QRS amplitude
• Electrical alternans (alternating variation in the QRS amplitude)
• Absent apex beat