基本的な生活支援 Ii: 気道・呼吸と継続的な心肺蘇生法

Continued CPR with integrated respiratory support is essential to ensure that your patient remains perfused and oxygenated until such time as spontaneous circulation is restored. CPR and defibrillation, discussed in the previous Basic Life support video, are the most important interventions for patients with cardiac arrest. Respiratory support, which includes establishing an airway and rescue breathing, is begun only after cardiac compressions are underway and defibrillation has been performed.

This video describes how to establish an airway using a bag-valve-mask, or BVM, and how to coordinate ventilation and CPR. Lastly, we’ll also discuss some troubleshooting steps, which includes using an oropharyngeal airway, or OPA.

“Note that ventilation requires a second rescuer. While the first rescuer performs continuous, high-quality chest compressions, the second rescuer performs all the steps needed to ventilate the patient. Ventilation should never be allowed to interfere with chest compressions. If there are insufficient personnel to do both, then compressions are the priority.”

While chest compressions are in progress, the first step is to attach the BVM to oxygen and set the flow rate to 10-15 liters per minute. Next, position the patient supine and flat, and remove pillows and other items that may obstruct positioning. Now stand directly at the head of the bed, as it not possible to properly perform BVM ventilation from the side, or from any other position. Now, to open the airway, place the palm of one hand on the patient’s forehead and the fingers of the other hand under the chin. Then, using the fingers, lift the chin thereby extending the neck. This is called the “head tilt-chin lift” maneuver, which should only be performed if there is no concern for cervical trauma. If there is concern for cervical trauma, try to open the airway by placing your fingers behind the angle of the mandible and displacing it anteriorly. This is known as the “jaw thrust” maneuver, which will not cause neck extension.

If the jaw thrust is not effective at opening the airway, the chin-lift should be utilized, as cervical spine injury is a theoretical concern, but airway occlusion is imminently life threatening. After opening the airway, place the mask over the patient’s mouth and nose, with the pointed part over the nasal bridge and the rounded part on the chin. The mask should not hang over the point of the chin, and should not cover the orbits.

Next, use the C/E technique to seal the mask. To do this, make a C with the dominant thumb and forefinger around the stem of the mask, and make an E with the third through fifth fingers of the same hand along the patient’s mandible, placing the fifth finger behind the angle of the mandible. Then, using your 3rd to 5th fingers, pull the patient’s face up into the mask. Do not push the mask down on the face, as this will make ventilation more difficult. With the mask firmly sealed against the patient’s face, air from the bag will enter the lungs and not leak out into the room.

At this point, with the mask sealed against the patient’s face, chest compressions should be paused to begin ventilations. While maintaining the mask seal, squeeze the bag with the opposite hand to inflate the lungs. Give two slow breaths, squeezing the bag over one second and then releasing it over one second. Watch the patient to see the chest rise with each breath. This is the only indication of effective ventilation since pulse-oximetry cannot be used when the patient does not have a pulse. Insufflate only enough air to produce a visible chest rise, as hyperventilation will raise the intrathoracic pressure, which in turn impedes blood return to the heart and reduces cardiac output.

Immediately after the first two breaths are administered, resume chest compressions. Counting out loud, give 30 chest compressions and pause for 2 breaths. Continue this ratio of 30 compressions and 2 breaths for 5 cycles, or 2 minutes — timed by a clock. At this point, pause CPR for a rhythm check, and if the rhythm is shockable, perform defibrillation as described in the previous video on basic life support. If the rhythm is not shockable, continue with the CPR.

If the patient’s chest did not rise with ventilation, then one should resume chest compressions and perform some troubleshooting steps. Knowledge of how to troubleshoot ineffective ventilation is essential for all providers, as the standard technique often does not produce the necessary chest rise.

First, check the positioning. Are you standing directly at the head of the bed? Is the patient supine with no pillow or other obstructions? If patient and rescuer positioning are appropriate, reposition your hands, and try again to open the airway using head tilt-chin lift and/or jaw thrust maneuver, and then attempt to ventilate again.

If still unable to ventilate, switch to the two-person technique, in which the rescuer uses both hands to perform the C/E technique to seal the mask to the face and opens airway using both chin lift and jaw thrust technique, while an assistant squeezes the bag to inflate the lungs.

If the two-person technique is not successful, insert an oropharyngeal airway, or OPA. The first step is to select the correct size OPA, which is the one that extends from the corner of the mouth to the earlobe. Insert the hooked end into the mouth, over the base of the tongue. This will pull the tongue forward, out of the hypopharynx. An alternative method is to insert it upside-down, while simultaneously turning it as it passes over the base of the tongue. Take care not to push the tongue farther back into the hypopharynx.

“While chest compressions and defibrillation are more important than respiratory support, patients with prolonged resuscitations will benefit from ventilation, and it should be performed whenever there is sufficient manpower and equipment to do so. The rescuer should continue performing 30 compressions for every two breaths, and pause every 5 cycles or two minutes for a rhythm check.”

“One should stop CPR only when it is no longer clinically indicated. Indications for terminating CPR include: the patient regains consciousness, the patient remains unconscious but regains a pulse, or further resuscitation is futile and you intend to pronounce the patient dead.”

“Advanced life support measures like intubation or vascular access should be considered only once help arrives and you’re sure that these maneuvers can be performed without detracting from the quality and continuity of CPR.”

You have just watched a JoVE video describing how to ventilate a patient for whom CPR is already underway, how to coordinate chest compressions with ventilation, and how to troubleshoot when the ventilation does not produce adequate chest rise. As always, thanks for watching!