Pulseless Electrical Activity
is a clinical condition characterized by unresponsiveness and impalpable pulse in the presence of sufficient electrical discharge.
A lack of ventricular impulse often points to the absence of ventricular contraction, but the contrary is not always true. It means that the electrical activity is pertinent, but not sufficient, condition for contraction. In the case of cardiac arrest, the organized ventricular electrical activity does not usually follow sufficient ventricular response. The word “sufficient” is being used to describe a degree of ventricular mechanical activity that is adequate to generate a palpable pulse.
Pulseless electrical activity is found initially in about 55% of people in cardiac arrest.
These possible causes are remembered as the 6 Hs and the 6 Ts:
⚫ 6 Hs
1.Hypovolemia
2.Hypoxia
3.Hydrogen ion (acidosis)
4.Hypo/hyperkalemia
5.Hypothermia
6.Hypoglycemia
⚫ 6 Ts
1.Tablets or toxins (Drug overdose)
2.Cardiac Tamponade
3.Tension pneumothorax
4.Thrombosis (myocardial infarction, pulmonary embolism)
5.Tachycardia
6.Trauma (hypovolemia from blood loss)
A study found that 68% of the recorded in-hospital deaths and 10% of all in-hospital deaths were attributed to pulseless electrical activity. In addition, hospitalized patients are more likely to have pulmonary embolism among other complications. Pulseless electrical activity is the first documented rhythm in 30 to 38% of adults with in-hospital cardiac arrest. Beta blockers and calcium channel blockers may alter contractility, leading to increased susceptibility and resistance to treatment. Women are more likely to develop pulseless electrical activity as compared to the male population. The risk of pulseless electrical activity increases over the age of 70, especially in the female population.
Treatment
The first step in managing pulseless electrical activity is to begin chest compressions according to ACLS protocol followed by administrating epinephrine every 3 to 5 minutes, while simultaneously looking for any reversible causes. Once a diagnosis is made, begin immediate specific management i.e., decompression of pneumothorax, pericardial drain for tamponade, fluids infusion for hypovolemia, correction of body temperature for hypothermia, administration of thrombolytics for myocardial infarction or pulmonary embolism. An arterial blood gas and serum electrolytes should be obtained during the resuscitation process.
Epinephrine should be administered in 1 mg doses intravenously/intraosseously every 3 to 5 minutes during pulseless electrical activity arrest. Each dose should be followed by 20 ml of flush and elevating the arm for 10 to 20 seconds for better perfusion. Higher doses of epinephrine have not shown to improve survival or neurologic outcomes in most patients. Selected patients, like those with beta blockers or calcium channel blockers overdose, may benefit from higher-dose epinephrine. It can also be given via endotracheal tube after mixing 2 mg in 10 ml of normal saline.
If the detected rhythm is bradycardia that is associated with hypotension, then atropine (1 mg IV every 3-5 min, up to three doses) should be administered. This is considered the optimal dose, beyond which no further benefit will occur. Note that atropine may cause pupillary dilation; therefore, this sign cannot be used to assess neurologic function.
Sodium bicarbonate may be used only in patients with severe, systemic acidosis, hyperkalemia, or tricarboxylic acid overdose. The dose is 1 mEq/kg. Avoid routine administration of sodium bicarbonate as it worsens intracellular and intracerebral acidosis without affecting mortality.
Pericardial drainage and emergent surgery may be lifesaving in appropriate patients with pulseless electrical activity. In a patient with a refractory case and chest trauma, a thoracotomy may be performed. Near pulseless electrical activity or a very low-output state may also be managed with the circulatory assistance (e.g., intra-aortic balloon pump, extracorporeal membrane oxygenation, cardiopulmonary bypass, and ventricular assist device).
The chances of a successful outcome depend on a very coordinated resuscitation process. There should be a specific person responsible for specific steps and a good team leader.
