Question 5

Last updated 30/04/2017 - 18:05
 Topic: Cardiac Arrest and Resuscitation
Pass rate
94%
Other SAQs in this topic:
Other SAQs in this paper:


You are working as an ICU specialist in a small regional hospital. You are called to give urgent assistance to a 65-year-old male who has presented to the Emergency Department with increasing shortness of breath, one week after discharge from a metropolitan hospital following apparently uncomplicated cardiac surgery.

Post-intubation, he has rapidly deteriorated and is now unresponsive with no recordable blood pressure. The cardiac monitor shows sinus tachycardia.

a)    Outline your response to this crisis.    (40% marks)

b)    Other than cardiac tamponade ,what additional diagnoses need to be considered? (25% marks)

c)    List the clinical signs indicating cardiac tamponade that may have been present prior to the cardiac arrest. (15% marks)


d)    Describe how you would perform blind pericardiocentesis.    (20% marks)

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College answer

Confirm cardiac arrest

Good BLS i.e.:

  • Check ETT position
  • Listen to chest 
  • Confirm ETCO2 trace (may not be reliable in complete arrest with absent pulmonary blood flow) 
  •  Check adequate CPR: 
    • Correct position (lower half of sternum)
    • Correct rate/depth and technique (depress 4 – 5 cm at 100 – 120 compressions/min 
    • Asynchronous ventilation with respiratory rate 8 – 10) 

Call for additional help

          Local surgical team may be able to re-open sternotomy

Confirm IV access/intraosseous if needed

Adrenaline 1 mg IV immediately and then with alternate cycles

Bolus i.v. fluid as PEA

Continue CPR for 2 min

Rhythm check at 2 min – continue chest compressions, other responders stand clear, charge defibrillator to 200J, pause compressions, all clear, check rhythm and if non-shockable dump charge Immediately continue CPR for further 2 min

Look for and treat reversible causes (needle thoracostomy / pericardiostomy etc – 4Hs and 4Ts)

b)                                                                                                                                  

  • Massive pulmonary emboli                                                                          
  • Pneumothorax with tension                                                                         
  • Hypovolaemia from bleeding elsewhere                                                   
  • Graft occlusion and myocardial infarction                                         
  • Septic shock possible (post op pneumonia/empyema/sternal wound infection)                                

c)                                                                                                                                  

  • Distended neck veins                                                                                   
  • Muffled heart sounds 
  • Hypotension & tachycardia
  • Pulsus paradoxus (may be seen on oximetry trace) Absent apex beat

d)                                                                                                                                  

  • 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 the needle is advanced
  • 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

Additional Examiners‟ Comments:

A substantial number of candidates failed to recognise a cardiac arrest. Many of the answers were at a junior level e.g. listing the causes of cardiac arrest (Hs and Ts) without reference to this clinical scenario. The question on the technique of blind pericardiocentesis was also badly answered. 

Discussion

This question is in many ways identical to Question 15 from the first paper of 2011.The discussion section was copy-pasted below to simplify revision. Interestingly, though some of the candidates failed to identify cardiac arrest, the pass rate suggests that this was not essential. 

a)

  • 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

b)

  • Other "four Hs and four Ts" with reference to  this scenario:
    • Hypoxia due to oesophageal intubation
    • Hypovolemia due to dehydration (too short of breath to drink!)
    • Hyper/hypokalemia due to cardiac drug side effects, eg. frusemide or spironolactone
    • Hyper/hypothermia is unlikely, but cannot be ruled out without actually measuring the temperature
    • Tension pneumothorax this late is unlikely, but could be the result of a ruptured emphysematous bull
    • Tamponade is already mentioned, and isthe  most likely
    • Toxins eg. drug intoxication
    • Thrombus i.e. PE or MI - PE coudl easily give rise to PEA of this sort, and intracardiac thrombus could be the consequences of cardiac surgery

c)

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 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

d)

The approach is as follows:

  • Raise the head of the bed 45° if the situation permits
  • 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.
  • Withdraw fluid until cardiac output improves
  • Advance guidewire and dilate over it.
  • Advance pigtail catheter over guidewire, and suture in place

The college answer also suggests one connect  an ECG lead (one of the chest leads) to the base of the needle  and watch the ECG to look for a change  in  the  QRS  morphology,   or  ST  elevation  if  the  needle  contacts  the myocardium.

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