Thoracic Pump Theory

The chest compressions cause a rise in the intrathoracic pressures more than that of extrathoracic regions, which cause the blood to flow. The direction of flow of blood toward the arterial tree is explained by the presence of venous valves, which prevent retrograde flow of blood at the thoracic inlet.

Cardiac Pump Theory

This theory states that blood flow is generated due to compression of the heart between the sternum and vertebral column.

Transesophageal echocardiography (TEE) during CPR in humans has helped in real-time visualization of changes in the heart and blood flow. During the chest’s compression, blood is ejected from the ventricles into the aorta and pulmonary system while the tricuspid and mitral valves close. When the pressure on the chest is released, the pressure gradient allows the heart’s venous flow. Any factors that affect the intrathoracic pressure like high-pressure mechanical ventilation, inadequate recoil of the chest also hinders adequate heart-filling and decreases chances of restoration of spontaneous circulation (ROSC). Providing adequate chest compressions is vital soon after a sudden cardiac arrest (SCA) because blood flow rather than oxygen content is the limiting factor for oxygen delivery to vital organs like the brain and heart. In most cases, this holds unless hypoxia is the cause of the arrest as in conditions like suffocation or drowning.

Assess for Breathing and Pulse

The victim’s breathing and pulse should be assessed simultaneously to minimize delay, and this should not take more than 10 seconds.

To assess breathing:

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  Look for chest rise and fall.

  
  
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  If breathing, monitor victim until help arrives.

  
  
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  If gasping or not breathing, it indicates cardiac arrest.

To assess pulse:

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  In an adult, palpate the carotid.

  
  
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  If no pulse can be felt within 10 seconds, initiate high-quality CPR with chest compressions.

To locate the carotid, locate the trachea using two or three fingers, and slide them to the groove between the trachea and muscles. If no pulse can be palpated within 10 seconds, chest compressions should be started. The assessment of breathing and pulse, followed by appropriate action, is tabulated below (Table 40.1).

Abbreviation: CPR, cardiopulmonary resuscitation.

Chest Compressions

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  Rate: 100 to 120/min.

  
  
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  Depth: At least 2 inches (5 cm).

  
  
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  Push hard and push fast.

  
  
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  Allow adequate chest recoil after each compression.

  
  
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  Minimize interruptions in chest compression.

If two rescuers are available, then a compres­sion is to ventilation ratio of 30:2 has to be
maintained.

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  The victim should preferably be placed on a firm surface in order to provide effective chest compressions. A soft surface does not allow adequate compression for blood pumping, and the compression provided will push the body into the soft surface.

Steps to Provide Good Quality Chest Compressions

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  Position yourself by the victim’s side.

  
  
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  Make sure the victim is lying supine and on a firm surface. If the victim is in the prone position, positioning should be done carefully, keeping the head, neck, and torso in a line.

  
  
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  Positioning yourself: Heel of one hand rests in the center of the victim’s chest on the lower half of the breastbone (sternum). Heel of the other hand rests on top of the first hand. Position yourself such that your shoulders are directly over your hands.

  
  
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  Provide chest compressions at a rate of 100 to 120/min.

  
  
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  Push at least 5 cm during each compression.

  
  
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  Allow adequate chest recoil after each compression.

  
  
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  Minimize interruptions.

Providing Breaths during CPR

The victim’s airway has to be opened using two maneuvers:

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  Head tilt-chin lift.

  
  
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  Jaw thrust.

If a cervical spine injury is suspected, use ONLY jaw thrust maneuver to minimize neck spine movement.

Primary Assessment

The unconscious patient’s primary assessment is done after the BLS, while in conscious patients, the primary assessment is done right away. The primary assessment is done under the following heads:

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  A—airway.

  
  
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  B—breathing.

  
  
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  C—circulation.

  
  
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  D—disability.

  
  
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  E—exposure.

Secondary Assessment

This involves a focused history and search for the cause of cardiac arrest. A focused history is recommended by the American Heart Association (AHA) using the mnemonic SAMPLE.

S—signs and symptoms.

A—allergies.

M—medications (including the last dose taken).

P—past medical history.

L—last meal consumed.

E—events.

The most common causes of cardiac arrest should be kept in mind while managing cardiac arrest (Table 40.5).

When the patient shows ROSC, post cardiac arrest care should be initiated.

The cardiac arrest algorithm consists of two limbs: The management of a shockable rhythm, while the other is regarding the nonshockable rhythm, including asystole and pulseless elec­trical activity (PEA).

Following 2 minutes of uninterrupted CPR, a rhythm check should be done, which should not exceed 10 seconds. Other noteworthy points are as follows:

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  In the case of no electrical activity, epinephrine bolus is given, and chest compressions should be resumed.

  
  
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  If electrical activity is present, then the pulse should be palpated.

  
  
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  If palpable, then post cardiac arrest care is initiated.

  
  
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  If no pulse is palpable or there is a doubt regarding the pulse palpability, then the chest compressions should be resumed without exceeding an interruption of 10 seconds (Flowchart 40.2).

Optimization of Oxygenation and Ventilation

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  An advanced airway can be placed for mechanical support of breathing in an unconscious/unresponsive patient.

  
  
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  Continuous waveform capnography to be used to confirm and monitor correct endotracheal tube (ETT) placement.

  
  
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  Excessive ventilation should be avoided.

  
  
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  100% oxygen can be administered until the patient arrives in an advanced center and reduced thereafter to maintain a saturation of at least 94%.

Optimization of Hemodynamics

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  Intervene whenever systolic blood pressure (SBP) < 90 mm Hg, initially by obtaining intravenous (IV) access.

  
  
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  Fluid bolus—1 to 2 L to be administered, normal saline or Ringer lactate.

  
  
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  Norepinephrine (0.1–0.5 µg/kg/min)/epine­phrine (0.1–0.5 µg/kg/min) or dopa­mine (5–10 µg/kg/min) infusion titrated to attain SBP > 90 mm Hg or a mean arterial pressure of > 65 mm Hg.

Initiate Targeted Temperature Management

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  Targeted temperature management is started in those who remain comatose or unresponsive despite ROSC after cardiac arrest, with a target to maintain a constant temperature between 32 and 36ºC for a period of 24 hours to improve the neuro­logical outcome after cardiac arrest.

  
  
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  The optimal method to achieve the target temperature is unknown, but a combination of various techniques like the rapid infusion of ice-cold, isotonic, nonglucose containing liquid (30 mL/kg), surface cooling devices, or simple surface techniques like ice bags are used commonly.

Immediate Coronary Reperfusion by PCI

Twelve-lead ECG should be obtained, and in cases of ST-elevation myocardial infarction (STEMI) or high suspicion of acute myocardial infarction (AMI), reperfusion should be planned and performed.

Immediate Neurologic Care

A neurologic assessment should be done, and targeted temperature monitoring (TTM) should be considered if the patient does not follow commands.

The prognostication of neurological outcome should be done after 72 hours of spontaneous circulation return in those who did not receive TTM and after 72 hours of TTM in those who received it.

Recommendations

Rate: 100 to 120/min.

Location: In infants, two fingers are used, placed below the inframammary line on the sternum.

In children, the lower half of the sternum (avoiding the xiphoid process) with one or two hands.

Depth of compression: One-third of the antero­posterior diameter of the chest (approximately 1.5 inches [4 cm] in infants to 2 inches [5 cm] in children).

The guidelines also recommend the usage of feedback devices to ensure adequate rate and depth.

A manual defibrillator is preferable in infants when a health care provider identifies a shockable rhythm. An AED with pediatric attenuator and pediatric pads can be used in children up to 8 years, with pads placed in an anteroposterior position.

In pediatric cardiac arrest, initial defibrillation energy of 2 J/kg is used and may be increased to 4 J/kg in the second shock. Increased energy levels may be subsequently considered but should not exceed 10 J/kg. If a pediatric defibrillator is not available, then an adult AED can be used without hesitation.

For pediatric patients, management of different life-threatening arrhythmias, PEA arrest/asystole, or ventricular fibrillation (VF)/ventricular tachy­cardia (VT) arrest is similar to adults, except for the dosage (defibrillation/medication) for children is weight-based. Actual body weight is recommended to calculate initial resuscitation drug doses. Vascular access can be challenging in critically ill children; therefore, intraosseous (IO) access is recommended in difficult IV access cases.