Basic Life Support: Cardiopulmonary Resuscitation and Defibrillation
Source: Julianna Jung, MD, FACEP, Associate Professor of Emergency Medicine, The Johns Hopkins University School of Medicine, Maryland, USA
High-quali…
1. Assess the patient
- Assess responsiveness by speaking loudly and stimulating the patient. If the patient is unresponsive, the diagnosis is cardiac arrest until proven otherwise.
- Assess circulation by palpating the carotid artery. Do this for no more than 10 seconds; longer assessment time delays initiation of resuscitation.
- Assess airway and breathing by observing for respiratory effort while you are palpating the pulse. This is called "CAB assessment" because the emphasis is on circulation; airway/breathing are secondary considerations.
- Call for help as soon as you confirm that the patient is indeed unresponsive.
2. Ask for emergency equipment. The most important item to get right away is a defibrillator.
3. Position the patient and rescuer for chest compressions.
- Roll the patient onto the back.
- Make the bed flat and get railings out of the way. Many hospital beds have a CPR level to allow this to be done quickly.
- Place a backboard under the patient. Chest compressions performed on a soft surface like a bed are not effective, so this is critical for the success of the resuscitation. Mechanical energy will flow down the path of least resistance, and your compression will deform the most compressible object under it. For a patient in a bed, this will be the mattress. Placing a backboard under the patient prevents compression of the mattress, ensuring that your compression deforms the chest wall instead. This allows compression of the heart, providing cardiac output.
- Position yourself at an appropriate height above the patient so that the compressions are more ergonomic and effective. This is most easily accomplished by standing on a step stool. Incorrect positioning may lead to less effective compressions and greater rescuer fatigue.
4. Perform chest compressions.
Complete the steps below quickly. The first compression must be delivered within 30 seconds of the time of arrest.
- Place the heel of one hand directly over the sternum at the nipple line. Make sure this hand is in the midline of the patient's body and not off to one side.
- Place the other hand over the first hand, interlacing the fingers.
- Lock the elbows.
- Position the body so that the elbows are directly over the wrists, and the shoulders are directly over the elbows. If you are not able to position yourself correctly, you are too low relative to the patient and need to lower the bed or use a step stool as discussed previously.
- Moving your entire body downward like a piston, chest compressions should be performed at a depth of at least 2 inches, but not more than 2.4 inches, or 5 to 6 centimeters, for adults. Adequate compression depth is essential in order to provide sufficient stroke volume to perfuse the heart and brain.
- Release pressure on the sternum completely between compressions. Under normal circumstances, negative interthoracic pressure causes blood to fill the heart. Leaning on the sternum raises interthoracic pressure and decreases cardiac filling, thereby decreasing stroke volume.
- Depress the sternum again as above, and repeat these last two steps 100-120 times per minute. Correct rate is essential - compressing too slowly directly reduces cardiac output, while compressing too quickly impairs filling and decreases stroke volume.
- Continue compressions without interruption until resuscitation equipment arrives. CPR continuity is a major determinant of survival. Do not pause CPR to perform nonessential tasks like removing clothing or auscultating the heart. Even essential tasks like airway management and intravenous access should not be permitted to disrupt CPR.
- Switch rescuers when needed. Chest compressions are exhausting, and if the quality of your CPR is suboptimal due to fatigue, have another rescuer step in. Be sure to coordinate switches so that there are no pauses in compressions.
5. Set up the defibrillator as soon as it arrives.
- Attach a set of pads to the defibrillator cable. If the paddles are attached when the defibrillator arrives, these will need to be detached first.
- Place the pads on the patient. Pad positions are illustrated on the pads themselves, though there are several options for positioning. The most common options are:
- Anteroposterior: Pads are placed on the left precordium and left back upper back. The patient will need to be rolled to place the posterior pad.
- Anterolateral: Place pads over the right sternal border and apex of the heart.
- Turn on the defibrillator.
6. Analyze the rhythm.
The instructions below assume that the defibrillator is being used in manual mode. For automated defibrillators, follow the instructions provided by the machine.
- Stop chest compressions to reveal the underlying rhythm, as compressions create electrical interference that will make it impossible to interpret the rhythm.
- Determine if the rhythm is shockable. The two shockable cardiac arrest rhythms are: one, ventricular fibrillation (VF), characterized by chaotic, disorganized electrical activity; and two, pulseless ventricular tachycardia (VT), a rapid, wide-complex rhythm without a detectable pulse.
- Ventricular fibrillation is a randomly fluctuating pattern without organized QRS complexes. There is no predictability or pattern to it whatsoever.
- Ventricular tachycardia is a rapid, wide-complex rhythm, usually more than 150 beats per minute. The QRS complexes are so wide that one just segues into the next, without discernible T-waves.
- If the rhythm is not shockable, resume chest compressions for two minutes, at which time the rhythm should be rechecked.
- If the rhythm is shockable, resume chest compressions while preparing to deliver a shock.
7. Deliver a shock (for shockable rhythms only).
- Make sure that the machine is set to the correct dose of electricity (200J for adults).
- Press the "charge" button.
- Wait until the defibrillator is fully charged. The high-pitched charging tone will get louder when the machine is ready.
- Clear all personnel away from the patient and the bed - make sure that nobody is in physical contact with the patient.
- Press the "shock" button.
- The high-pitched tone will stop, and the patient will "jump," indicating that electricity was delivered successfully.
Resume CPR immediately after delivering the shock, and continue for two minutes before pausing again to reassess the rhythm. Notice that there has been no mention of ventilation, vascular access, or drugs up to this point. That is because these are lower-priority interventions, with less impact on cardiac arrest survival. In the first few minutes of resuscitation, the priorities are rapid recognition of arrest, initiation of high-quality chest compressions, and performance of defibrillation when indicated.
1. Assess the patient
- Assess responsiveness by speaking loudly and stimulating the patient. If the patient is unresponsive, the diagnosis is cardiac arrest until proven otherwise.
- Assess circulation by palpating the carotid artery. Do this for no more than 10 seconds; longer assessment time delays initiation of resuscitation.
- Assess airway and breathing by observing for respiratory effort while you are palpating the pulse. This is called "CAB assessment" because the emphasis is on circulation; airway/breathing are secondary considerations.
- Call for help as soon as you confirm that the patient is indeed unresponsive.
2. Ask for emergency equipment. The most important item to get right away is a defibrillator.
3. Position the patient and rescuer for chest compressions.
- Roll the patient onto the back.
- Make the bed flat and get railings out of the way. Many hospital beds have a CPR level to allow this to be done quickly.
- Place a backboard under the patient. Chest compressions performed on a soft surface like a bed are not effective, so this is critical for the success of the resuscitation. Mechanical energy will flow down the path of least resistance, and your compression will deform the most compressible object under it. For a patient in a bed, this will be the mattress. Placing a backboard under the patient prevents compression of the mattress, ensuring that your compression deforms the chest wall instead. This allows compression of the heart, providing cardiac output.
- Position yourself at an appropriate height above the patient so that the compressions are more ergonomic and effective. This is most easily accomplished by standing on a step stool. Incorrect positioning may lead to less effective compressions and greater rescuer fatigue.
4. Perform chest compressions.
Complete the steps below quickly. The first compression must be delivered within 30 seconds of the time of arrest.
- Place the heel of one hand directly over the sternum at the nipple line. Make sure this hand is in the midline of the patient's body and not off to one side.
- Place the other hand over the first hand, interlacing the fingers.
- Lock the elbows.
- Position the body so that the elbows are directly over the wrists, and the shoulders are directly over the elbows. If you are not able to position yourself correctly, you are too low relative to the patient and need to lower the bed or use a step stool as discussed previously.
- Moving your entire body downward like a piston, chest compressions should be performed at a depth of at least 2 inches, but not more than 2.4 inches, or 5 to 6 centimeters, for adults. Adequate compression depth is essential in order to provide sufficient stroke volume to perfuse the heart and brain.
- Release pressure on the sternum completely between compressions. Under normal circumstances, negative interthoracic pressure causes blood to fill the heart. Leaning on the sternum raises interthoracic pressure and decreases cardiac filling, thereby decreasing stroke volume.
- Depress the sternum again as above, and repeat these last two steps 100-120 times per minute. Correct rate is essential - compressing too slowly directly reduces cardiac output, while compressing too quickly impairs filling and decreases stroke volume.
- Continue compressions without interruption until resuscitation equipment arrives. CPR continuity is a major determinant of survival. Do not pause CPR to perform nonessential tasks like removing clothing or auscultating the heart. Even essential tasks like airway management and intravenous access should not be permitted to disrupt CPR.
- Switch rescuers when needed. Chest compressions are exhausting, and if the quality of your CPR is suboptimal due to fatigue, have another rescuer step in. Be sure to coordinate switches so that there are no pauses in compressions.
5. Set up the defibrillator as soon as it arrives.
- Attach a set of pads to the defibrillator cable. If the paddles are attached when the defibrillator arrives, these will need to be detached first.
- Place the pads on the patient. Pad positions are illustrated on the pads themselves, though there are several options for positioning. The most common options are:
- Anteroposterior: Pads are placed on the left precordium and left back upper back. The patient will need to be rolled to place the posterior pad.
- Anterolateral: Place pads over the right sternal border and apex of the heart.
- Turn on the defibrillator.
6. Analyze the rhythm.
The instructions below assume that the defibrillator is being used in manual mode. For automated defibrillators, follow the instructions provided by the machine.
- Stop chest compressions to reveal the underlying rhythm, as compressions create electrical interference that will make it impossible to interpret the rhythm.
- Determine if the rhythm is shockable. The two shockable cardiac arrest rhythms are: one, ventricular fibrillation (VF), characterized by chaotic, disorganized electrical activity; and two, pulseless ventricular tachycardia (VT), a rapid, wide-complex rhythm without a detectable pulse.
- Ventricular fibrillation is a randomly fluctuating pattern without organized QRS complexes. There is no predictability or pattern to it whatsoever.
- Ventricular tachycardia is a rapid, wide-complex rhythm, usually more than 150 beats per minute. The QRS complexes are so wide that one just segues into the next, without discernible T-waves.
- If the rhythm is not shockable, resume chest compressions for two minutes, at which time the rhythm should be rechecked.
- If the rhythm is shockable, resume chest compressions while preparing to deliver a shock.
7. Deliver a shock (for shockable rhythms only).
- Make sure that the machine is set to the correct dose of electricity (200J for adults).
- Press the "charge" button.
- Wait until the defibrillator is fully charged. The high-pitched charging tone will get louder when the machine is ready.
- Clear all personnel away from the patient and the bed - make sure that nobody is in physical contact with the patient.
- Press the "shock" button.
- The high-pitched tone will stop, and the patient will "jump," indicating that electricity was delivered successfully.
Resume CPR immediately after delivering the shock, and continue for two minutes before pausing again to reassess the rhythm. Notice that there has been no mention of ventilation, vascular access, or drugs up to this point. That is because these are lower-priority interventions, with less impact on cardiac arrest survival. In the first few minutes of resuscitation, the priorities are rapid recognition of arrest, initiation of high-quality chest compressions, and performance of defibrillation when indicated.
Q1: Why is high-quality CPR the most important factor in cardiac arrest survival?
High-quality cardiopulmonary resuscitation is the single most important determinant of intact survival in cardiac arrest. Effective CPR maintains blood flow to vital organs during cardiac arrest, directly improving patient outcomes. Healthcare workers must perform CPR correctly to maximize survival rates, as many providers perform it incorrectly, resulting in suboptimal outcomes.
Q2: What are the essential elements of high-quality CPR?
High-quality CPR consists of essential elements grounded in physiologic principles that enhance survival outcomes. Each step has a specific physiologic basis designed to maintain adequate circulation and oxygenation during cardiac arrest. Understanding and optimizing these elements is critical for healthcare workers to perform effective resuscitation and improve patient survival rates.
Q3: How does understanding the physiologic basis of CPR improve resuscitation performance?
Understanding the physiologic basis for each CPR step enables healthcare workers to optimize their technique and enhance survival outcomes. When providers comprehend why each intervention matters, they can perform CPR more effectively and maintain better quality throughout resuscitation. This knowledge-based approach directly addresses the gap between conceptual simplicity and correct clinical performance.
Q4: What role does intervention prioritization play in cardiac arrest management?
Appropriate prioritization of interventions in cardiac arrest is essential for optimizing resuscitation outcomes. Determining which interventions to perform first and in what sequence directly impacts patient survival. Proper prioritization ensures that the most critical life-saving measures receive immediate attention during the limited window of opportunity in cardiac arrest.
Q5: Why do many healthcare providers perform CPR incorrectly despite its conceptual simplicity?
Despite CPR's conceptual simplicity, many providers perform it incorrectly, resulting in suboptimal survival outcomes for patients. The gap between understanding CPR theory and executing it correctly in clinical practice remains significant. This discrepancy highlights the importance of proper training, technique optimization, and ongoing performance monitoring to ensure high-quality resuscitation.
Q6: What methods can optimize resuscitation performance during cardiac arrest?
Optimizing resuscitation performance involves understanding the physiologic basis of CPR, prioritizing interventions appropriately, and maintaining high-quality technique throughout resuscitation. Methods include continuous monitoring of performance, correcting technique errors in real time, and ensuring all healthcare workers receive proper training. These approaches directly enhance survival outcomes in cardiac arrest patients.
Q7: How does CPR connect to airway management in comprehensive cardiac arrest care?
CPR is the foundation of cardiac arrest management, and airway management follows as a critical next step in comprehensive resuscitation. Effective breathing and continued cardiopulmonary resuscitation work together to maintain oxygenation and circulation. Integrating these interventions sequentially ensures optimal outcomes in emergency cardiac care.