Page 90 - Critical Care Notes

4223_Tab02_045-106 29/08/14 10:00 AM Page 84

CV
■ Consider antiarrhythmics (given without interrupting CPR):
■ Amiodarone: 300 mg IV or IO, may repeat 150 mg in 3–5 min.
■ Lidocaine: 1.0–1.5 mg/kg IV or IO, may repeat 0.5–0.75 mg/kg q5–10 min,
max 3 mg/kg.
■ Magnesium: 1–2 g IV or IO for torsades de pointes.
■ A 2011 study published in Circulation showed that patients with a shockable
rhythm (VF or pulseless VT) had better survival rates if CPR is paused for
only 10 sec or less before delivery of electric shock to the heart (preshock
pause) or a total of 20 sec or less pause in chest compressions both before
and after defibrillatory shock (perishock pause).
■ 76% of patients show signs of ongoing instability for several hours prior to
cardiac arrest.
■ 70% of patients show signs of respiratory distress within 8 hr of arrest.
■ 66% of patients show abnoral signs and symptoms within 6 hr of arrest.
Asystole or Pulseless Electrical Activity (PEA)
■ Resume CPR for 5 cycles (should last about 2 min).
■ Epinephrine: 1 mg IV or IO (2 to 2.5 mg ET) every 3–5 min or vasopressin:
40 units IV or IO, one time only. May use to replace 1st or 2nd dose of epi-
nephrine (given without interrupting CPR).

Intra-aortic Balloon Pump
Counterpulsation (IABP)
IABP counterpulsation provides temporary mechanical circulatory support.
Goals of IABP counterpulsation: increase O 2 to myocardium and coronary arteries,
decrease LV workload by decreasing impedance to ejection (afterload), and
increase cardiac output. An IABP device consists of a 30-cm polyurethane balloon
attached to one end of a large-bore catheter. The device is inserted into the femoral
artery at the groin, either percutaneously or via arteriotomy, with the balloon
wrapped tightly around the catheter. Once inserted, the catheter is advanced up
the aorta until the tip lies just beyond the origin of the left subclavian artery. When
in place, the balloon wrapping is released to allow periodic balloon inflations.
Effects

The intra-aortic balloon is inflated with helium at the onset of each diastolic
period (middle of T wave), when the aortic valve closes. The balloon is deflated
at the onset of ventricular systole, just before aortic valve opens (prior to QRS
complex). An arterial waveform can be used as an alternative to ECG triggering.
Inflation of the balloon increases the peak diastolic pressure and displaces
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