Cardiopulmonary resuscitation (CPR)

Cardiopulmonary resuscitation (CPR) is an emergency procedure that uses chest compressions and artificial ventilation to maintain blood flow and oxygenation during a cardiac arrest, when the heart stops beating or beats too ineffectively to circulate blood to the brain and other vital organs.

CPR is important because it provides oxygenated blood flow to all parts of the body and keeps organs alive until medical personnel arrive.

Cardiopulmonary resuscitation (CPR) for adults involves performing chest compressions with a depth of 5 cm (2 in) to 6 cm (2.4 in) at a rate of at least 100 to 120 compressions per minute. The rescuer can also offer artificial ventilation by either breathing air into the person's mouth or nose (mouth-to-mouth resuscitation) or using a device to deliver air into the person's lungs (mechanical ventilation). Current guidelines prioritize early and high-quality chest compressions over artificial ventilation. For untrained individuals, a simplified CPR method that focuses solely on chest compressions is recommended.

When dealing with children, it's important to note that, according to the 2015 American Heart Association guidelines, performing only compressions may not yield optimal results. This is because issues in children typically stem from respiratory problems rather than cardiac ones due to their young age. The recommended chest compression to breathing ratio is 30 to 2, meaning for every 30 chest compressions, it should be follow by 2 rescue breaths.

Cardiopulmonary resuscitation alone is unlikely to restart the heart. Its primary objective is to partially restore the flow of oxygenated blood to the brain and heart, thereby delaying tissue damage and extending the critical window for successful resuscitation without causing permanent brain damage. To restore a viable, perfusing heart rhythm, it is often necessary to administer an electric shock to the heart, known as defibrillation. Defibrillation is effective for specific heart rhythms, such as ventricular fibrillation or pulseless ventricular tachycardia, but it is less effective for rhythms like asystole or pulseless electrical activity, which typically require treatment of underlying conditions to restore cardiac function. When appropriate, delivering an early shock is recommended. In some cases, CPR may induce a shockable heart rhythm. In general, CPR should be continued until the individual experiences a return of spontaneous circulation (ROSC) or is declared deceased.

Indication

CPR is indicated for individuals who are unresponsive and either not breathing or exhibiting occasional agonal gasps, as this is indicative of a likely cardiac arrest. In cases where a person still possesses a pulse but is not breathing (experiencing respiratory arrest), artificial ventilations may be more suitable. However, due to the challenges individuals face in accurately determining the presence or absence of a pulse, CPR guidelines advise against instructing laypersons to check the pulse, while healthcare professionals are given the option to do so. For those in cardiac arrest resulting from trauma, CPR is considered potentially futile but is still recommended. Addressing the underlying cause, such as a tension pneumothorax or pericardial tamponade, may be beneficial in such cases.

Pathophysiology

Cardiopulmonary resuscitation (CPR) is administered to individuals experiencing cardiac arrest, aiming to oxygenate the blood and maintain cardiac output to keep vital organs alive. Blood circulation and oxygenation are vital for transporting oxygen to the body's tissues. The physiological process of Cardiopulmonary resuscitation involves creating a pressure gradient between the arterial and venous vascular beds, achieved through various mechanisms. Damage to the brain may occur after approximately four minutes without blood flow, and irreversible damage after about seven minutes. Typically, if blood flow is halted for one to two hours, body cells undergo necrosis. Therefore, the effectiveness of CPR is generally limited to instances where it is initiated within seven minutes of blood flow cessation.

The heart quickly loses its ability to maintain a normal rhythm in the absence of blood flow. Lower body temperatures, as observed in near-drowning incidents, can extend the brain's survival time. Following cardiac arrest, effective CPR ensures an adequate supply of oxygen to the brain, delaying brain stem death, and maintains the heart's responsiveness to defibrillation attempts. Deviating from the recommended compression rate of 100-120 compressions per minute, as per AHA guidelines, during CPR can lead to a net decrease in venous blood return needed to fill the heart. For instance, consistently using a compression rate above 120 compressions per minute throughout CPR may adversely impact survival rates and outcomes for the individual.

Procedure

Adults

Preparation

1. Ensure a safe scene. Do not put yourself or others at risk. Remove the danger or the patient. For example, you're in the middle of the road, or there are dangers of falling debris. Pick a spot that is safe and put away any items that could accidentally cause injury (ie. sharp objects).
2. Look for a response from the victim. Loudly ask if they are OK. Tap or squeeze their shoulder.
3. If there is no response, call 911 or have someone to call the number. Do not leave the victim! The 911 dispatcher can also guide you through the steps to take until paramedics arrive.
4. Ask someone nearby to get an automated external defibrillator (AED). People can usually find these in offices and many other public buildings.
5. Carefully lay the person on their back and kneel beside their chest. Make sure the surface they are lying on is hard enough.
6. Slightly tilt the person’s head back by lifting their chin.
7. Open the person's mouth and examine for obstructions and remove any loose obstructions (ie. vomit, or food). However, do not try to remove non-loose obstructions as you may end up pushing it farther into the airway.
8. Place your ear near the victim's mouth and listen for breathing sounds for 10 seconds. You can also check if their chest is going up and down. You may also check for a pulse by feeling the side of their neck.
9. If there is no breathing or only occasional gasps are heard, or if there is no pulse, then start CPR. However, if the person is unconscious but still breathing, do not perform CPR. Instead, assess if they have spinal injury. Do not move them if you suspect any spinal injury as you may accidentally worsen the injury.

CPR Steps

1. Place your hands, one on top of the other, and interlock your fingers.
2. Place your hands in the middle of the person's chest (right under the nipples).
3. Put the force of your body weight as you push your hands down hard using the heel of your hand, or the part just before your wrist. Keep your arms straight. Push at least 2 inches deep.
4. Keep pushing on the person's chest at the rate of 100-120 compressions per minute. Make sure you allow the chest to come all the way back up between compressions.
5. People who have CPR training can pause compressions to give the person two mouth-to-mouth rescue breaths for every 30 compressions (about 20 seconds or so).
6. To perform rescue breaths, ensure that the mouth is clear. Tilt the person's head slightly back, lift the chin, pinch the nose shut, place your mouth fully over theirs (or with a rescue breathing barrier device), and blow. Provide a 1 second breath to make the chest rise.
7. If the chest doesn't rise after the first breath, tilt the head, then try blowing again. If the chest still doesn't rise with the second breath, then there is a chance that the person might be choking. In this case, restart CPR with chest compressions.
8. Repeat the cycle doing 30 chest compressions and giving 2 rescue breaths. Before giving rescue breaths, check if the mouth has any loose objects, if there is, remove it. If you find an object and it is not loose, do not attempt to extract it. If you don't see an object, give two more rescue breaths. If the person's chest still does not rise, keep going with the cycles of chest compressions, checking for an object, and rescue breaths until medical help arrives or the person starts breathing on their own.

Children / Infants

Preparation

1. Check the scene, make sure it is safe.
2. Check the child or infant for consciousness. For children, tap the child's shoulder and loudly ask if they are OK. For infants, flick the sole of their foot to see if they respond to the stimuli.
3. If they are unresponsive, call out for someone to call 911 or use your cell phone to call 911 and put it on speakerphone while you start the CPR.
4. Place the child on their back. If they are lying on their stomach, turn the child over onto their back. The child should be lying on a hard flat surface.
5. Kneel beside their chest, tilt their head slightly back by lifting the chin.
6. Open the mouth and check for obstructions, remove any loose ones such as food or vomit. Do not attempt to take out non-loose obstructions like those inside their throat as you might end up pushing it farther into the airway.
7. Check for breathing and signs of life. Watch the chest for any normal movement, and place your ear close to their mouth to listen for breathing sounds. Note that, in infants, changes in their breathing patterns are normal, as they have periodic breathing. Do these for no more than 10 seconds.
8. If you hear no breathing or if you only hear occasional gasps, initiate CPR.

CPR Steps

1. Depending on the size of the child, use one or two hands.For infants, use two fingers, or two thumbs.
2. Place the heel of your hand at their sternum, which is in the center of the chest, and between and slightly below their nipples.
3. With your elbows locked and arms straight, lean over the child's chest and compress the child's chest two inches in depth (or one-third the depth of the chest) 30 times at a rate of 100 to 120 compressions per minute. For infants, the depth should be around 1.5 inches deep.
4. After the compressions, give breaths. For a child, give breaths by tilting the head back, lifting the chin, and pinching the nose. Place your mouth over the child's mouth and give two slow, gentle breaths — just enough to make the chest rise. For infants, place your mouth over their nose and mouth. For both, deliver two rescue breaths. Occasionally, check the mouth for any obstructions and remove loose ones.
5. If they are still not responding, resume the cycle of 30 compressions followed by two breaths. Make sure to clear the mouth for any loose obstructions, but do not remove those that are stuck or inside the throat. Keep this cycle going until help arrives or if the child/infant starts to breath on their own.

Don'ts

• Don't panic. If you are panicking, you won't be able to think properly.
• Don't give up. CPR can help to keep blood and oxygen flowing to the brain and other vital organs, which can increase the victim's chances of survival.
• Don't rock or jerk. Rocking or jerking your body during chest compressions can make it difficult to maintain proper depth and force.
• Don't bounce. Use your body weight to exert force. You should be the one pushing and not the other way around. Bouncing can also make it difficult to maintain proper depth and force. The proper way is to straighten the elbows while delivering compressions.
• Don't be afraid. It's possible to break ribs during CPR, but this is usually not serious. Don't be afraid to exert force as the benefit outweighs this disadvantage. Rib fractures are more likely to occur if CPR is performed incorrectly, so it's important to learn proper technique.
• Don't hesitate. Don't hesitate to ask for help. If you're overwhelmed, ask someone for help.

Guidelines for Cardiopulmonary resuscitation

In 2010, the American Heart Association and International Liaison Committee on Resuscitation updated their Cardiopulmonary resuscitation guidelines, placing a strong emphasis on high-quality CPR, defined as achieving an adequate rate and depth of compressions without excessive ventilation.  The sequence of interventions for all age groups, with the exception of newborns, was also revised from airway, breathing, chest compressions (ABC) to chest compressions, airway, breathing (CAB).  An important note to this change is that individuals suspected of experiencing respiratory arrest (due to airway obstruction, drug overdose, etc.) remain an exception to the revised sequence.

Key elements in performing effective CPR include minimizing interruptions in chest compressions, ensuring an appropriate speed and depth of compressions, allowing complete relaxation of pressure between compressions, and avoiding excessive ventilation. The impact of a few minutes of CPR prior to defibrillation compared to immediate defibrillation on outcomes remains unclear.

A normal CPR procedure uses chest compressions and ventilations (rescue breaths). But ventilations could be omitted for not trained rescuers aiding adults who suffer a cardiac arrest.

Guidelines suggest calling emergency medical services before initiating Cardiopulmonary resuscitation, with exceptions for drowning victims and children that were already unconscious when the rescuers arrive, in which case the call would be made after two minutes of CPR.

An exception to the standard compression-to-ventilation ratio of 30:2 arises when at least two trained rescuers are present, and the victim is a child, in which case a preferred ratio of 15:2 is recommended.  According to the AHA 2015 Guidelines, for newborns, the ratio is 30:2 when one rescuer is present and 15:2 when two rescuers are available.  In cases involving advanced airway treatments, such as an endotracheal tube or laryngeal mask airway, artificial ventilation should be administered without interrupting compressions, at a rate of 1 breath every 6 to 8 seconds (equivalent to 8–10 ventilations per minute).

Certain plastic shields and respirators are available for use during rescue breaths to create a more effective seal between the rescuer's mouth and the victim's, aiming to enhance the vacuum and prevent infections.

Standard CPR is administered with the victim lying in a supine position. In contrast, prone CPR, also known as reverse CPR, is applied to a victim lying face down. This involves turning the head to the side and compressing the back. This positioning is believed to potentially reduce the risk of complications such as vomiting and aspiration pneumonia. The American Heart Association's current guidelines advocate for CPR to be conducted in the supine position, and limits prone CPR for cases where turning the patient is not possible.

When a woman is pregnant and lies on her back, the uterus may exert pressure on the inferior vena cava, leading to a reduction in venous return. To address this, it is advised to shift the uterus to the left side. This can be achieved by positioning a pillow or towel under the woman's right hip, creating an angle of 15–30 degrees, while ensuring her shoulders remain flat on the ground. If this proves ineffective, healthcare professionals may need to consider emergency resuscitative hysterotomy.

Cardiopulmonary resuscitation Training Videos