Cardiopulmonary Resuscitation and Artificial Perfusion During Cardiac Arrest

Compressions

The 2015 resuscitation guidelines emphasize the importance of quality chest compression by recommending that clinicians focus on maintaining proper chest compression depth and rate. Compress the sternum to a depth of between 2.0 and 2.4 inches with a rate of between 100 and 120 compressions/min. Box 17.1 provides a summary of procedural recommendations for CPR. If possible, place a backboard under the victim to ensure appropriate thoracic compression. In addition, adjust the height of the bed or have the rescuer stand on top of a stepstool so that the entire weight of the rescuer above the waist is directed onto the patient's sternum ( Fig. 17.1 A ). This enhances the depth of compressions and helps prevent leaning on the patient's chest between compressions, which is another key deficiency that has been widely observed. Extend the arms fully and place them perpendicular to the patient's chest while making sure to pull away from the chest sufficiently between compressions to allow full chest recoil. Rotate rescuers aggressively (approximately every 2 to 3 minutes) to avoid deteriorating quality of compressions because of exhaustion. Properly delivered compressions are highly fatiguing, and rescuer bravado often interferes with the realization of declining CPR quality over time.

Minimize pauses in chest compressions because even short pauses have profound effects on coronary perfusion pressure and outcomes. As stated earlier, long pauses in chest compressions before delivery of a shock are associated with failure of defibrillation. Do not stop CPR to deliver medications because the drugs can be administered at the same time as the compressions. Keep pauses in chest compressions to a minimum (e.g., for procedures such as intubation or pulse checks).

Ventilations

Deliver ventilations at a rate of 8 to 10 breaths/min (see Fig. 17.1 B ). Hyperventilation (e.g., ventilation rates greater than 30/min) is common during resuscitation. To prevent unwittingly hyperventilating the patient, one practical technique is to ask the rescuer who is providing ventilations to remove his or her hand completely off the bag-valve-mask apparatus between ventilations. The team leader should be vigilant in the observation of delivery of ventilations and should be ready to verbally prompt rescuers to ventilate the patient at the appropriate rate if hyperventilation is performed.

Pulse Checks

Pulse checks are generally performed too frequently during resuscitation efforts and take too much time. If a pulse cannot be readily felt within seconds, return to chest compressions as soon as possible. No studies have suggested that CPR is harmful to a patient with a very weak pulse, so use of a Doppler ultrasound device to detect the pulse is discouraged, as it is unnecessary and leads to increased pause times. If rescuers need ultrasound to find a pulse, the patient is at the very least markedly hypotensive and should probably be receiving CPR. Attempt pulse detection at the location of the carotid or femoral artery because peripheral pulse checks during profound shock or cardiac arrest states are notoriously unreliable. Frequently, a “pulse” can be detected during CPR itself; this phenomenon is often due to venous back pressure during compressions and does not indicate that compressions should be stopped, nor does it necessarily suggest that the compressions are of adequate quality.

Monitoring end-tidal CO ₂ pressure (P etco ₂ ) also affords an opportunity to detect a pulse during CPR. During ongoing resuscitation of a pulseless patient, capnography will generally remain low (often less than 20 mm Hg), which is indicative of low blood flow. If the patient achieves return of spontaneous circulation (ROSC), a sharp increase in the P etco ₂ value (usually greater than 25 to 30 mm Hg) is consistent with return of adequate perfusion.