You're pressing hard on someone's chest, trying to keep them alive, and you feel — and hear — a crack. Your stomach drops. Did you just break their ribs? Are you doing this wrong? Should you stop?
The answer is almost always no. CPR requires force. Real, meaningful force — enough to compress an adult chest 2 to 2.4 inches with every push. At that depth, ribs fracture in a significant portion of patients. Studies consistently put the rate of rib fractures during CPR at 30 to 80 percent. That's not a failure. That's physics.
This guide walks through every major complication that can occur during CPR — broken ribs, bleeding, aspiration, pneumothorax, lung damage — and explains what each one means, what you should do, and why imperfect CPR still saves lives when no CPR doesn't.
If you've ever hesitated to do CPR because you were afraid of hurting someone, this article is for you. Bystander CPR more than doubles survival rates after out-of-hospital cardiac arrest. The complications described here are manageable, treatable, and far less devastating than the alternative. A cracked rib can heal. Death can't be undone.
Understanding CPR complications also makes you a better responder. When blood appears at someone's mouth, you don't panic — you recognize it, you manage the airway, you keep going. When ribs crack under your hands, you don't freeze — you maintain depth and rate because you know that's exactly what's needed. Knowledge turns fear into confidence, and confidence saves lives.
There's also an important distinction that often gets lost in lay understanding: CPR isn't designed to be gentle. It's designed to work. Medical professionals and resuscitation researchers have known for decades that the force necessary to circulate blood during cardiac arrest frequently causes injury. That's a recognized, accepted trade-off embedded in every CPR guideline ever written. The American Heart Association doesn't soften it — compression depth requirements stay at 2 to 2.4 inches precisely because research shows that shallower compressions fail to generate adequate circulation.
So when you encounter complications — whether you're a bystander doing CPR for the first time or a trained responder who knows the anatomy — understanding the "why" behind each complication helps you respond appropriately instead of reflexively pulling back at the worst possible moment.
Let's break down every complication, how common it is, and exactly what to do when it happens.
Rib fractures occur in 30–80% of CPR cases. This does NOT mean you did anything wrong — it means you're compressing deeply enough. Continue CPR at the correct depth and rate. Stopping is what kills.
The most common CPR complication. Ribs crack under the force needed to circulate blood. In elderly or osteoporotic patients, it can happen with the very first compression.
Internal bleeding can result from rib fractures lacerating vessels, liver or spleen injury from compressions, or blood entering the airway from the lungs.
Stomach contents can reflux into the airway during CPR, especially if the patient vomited. This is a significant risk during rescue breathing.
A fractured rib can puncture the pleural space, collapsing the lung partially or fully. Tension pneumothorax is a life-threatening emergency requiring immediate needle decompression.
High compressions or improper hand placement can bruise or lacerate the liver and spleen. Correct hand placement in the center of the chest reduces this risk significantly.
The ribs aren't weak. But they weren't designed to absorb 100 high-force compressions per minute in the direction CPR demands. When you perform adult CPR, you're pushing down 2 to 2.4 inches into the chest — compressing the heart between the sternum and the spine to squeeze blood through the circulatory system. That's the only way compressions work.
That kind of force puts enormous stress on the rib cage. For younger, healthy adults with dense bone, ribs may hold. But in older adults, patients with osteoporosis, women (who statistically have lower bone density), or anyone with a history of steroid use or chronic illness, the ribs often can't take it. One study published in Resuscitation found rib fractures in over 80% of post-mortem CPR cases. Other studies in living patients report rates of 30 to 50 percent — but these likely undercount, since minor fractures often go undetected without imaging.
The sternum itself can crack too. Sternal fractures occur in roughly 30 to 40 percent of CPR cases, often alongside rib fractures.
So why do we still compress that hard? Because shallow compressions don't work. The cpr compression rate with full 2-to-2.4-inch depth. Every inch less than recommended dramatically reduces blood flow to the brain and heart. A cracked rib is survivable. Inadequate CPR leads to death or severe anoxic brain injury. There's no realistic trade-off here.
What should you do if you feel ribs break? Keep going. Maintain proper depth. Don't let the cracking sound cause you to lighten your compressions — that's the moment many bystanders unconsciously back off, and that's when CPR stops being effective. You may feel the chest become slightly easier to compress as structural integrity decreases — use that as a reminder to keep your depth consistent, not as a reason to push harder or softer than the target range.
The one time to reassess technique is if you notice you've drifted off-center. Check that your hands are on the lower half of the sternum — heel of one hand, other hand on top, fingers interlaced. That's correct position. If you're too far down on the xiphoid process or shifted sideways, reposition. But don't stop — reposition during compressions if you can, or with a single brief pause of no more than 10 seconds.
Causes: High-force compressions (2–2.4 inch depth) required to circulate blood. Bone density decreases with age, illness, osteoporosis, and corticosteroid use. First compression can fracture ribs in very frail patients.
Signs: Audible or palpable crack during compressions. Chest may feel different — less resistance or a noticeable pop. Rescuer may feel movement in the chest wall that wasn't there before.
What to do: Continue CPR without stopping. Maintain proper depth and rate. Do not reduce force to "protect" ribs — reduced compressions reduce survival. On hospital arrival, imaging will assess fractures. They heal with time; cardiac arrest does not recover on its own.
Causes: Fractured ribs can lacerate intercostal arteries or veins, causing hemothorax (blood in the chest cavity). Liver or spleen injury from misplaced compressions can cause intra-abdominal bleeding. Blood in the airway often comes from pulmonary contusion — bruising of lung tissue — or regurgitated stomach blood.
Signs: Blood from the mouth or nose during CPR. This is alarming visually but doesn't mean CPR has failed. Blood in the airway may come from the lungs (pink, frothy) or from the stomach (darker, more viscous).
What to do: If blood is in the mouth, turn the head to the side briefly to let it drain. If you have suction, use it between breath cycles. Continue chest compressions — do not stop for bleeding. Paramedics will manage internal bleeding on arrival. Correct hand placement (center of lower sternum) reduces abdominal organ risk.
Causes: Gastric reflux during CPR is common — compressions increase abdominal pressure. When stomach contents enter the airway, aspiration pneumonia can develop after resuscitation. Rescue breaths can also inflate the stomach if the airway isn't properly opened, increasing regurgitation risk.
Signs: Vomiting or regurgitation of stomach contents into the mouth. You may see fluid appearing at the lips. Gurgling sounds during rescue breaths suggest fluid in the airway.
What to do: Turn the head to the side and clear visible vomit with fingers or a cloth. Resume CPR immediately. Use suction if available. For hands-only CPR, aspiration from rescue breaths is avoided — this is one reason hands-only CPR is recommended for untrained bystanders. If using bag-valve-mask, ensure proper seal and avoid over-inflation to minimize stomach pressure.
Blood appearing at the mouth during CPR is one of the most alarming things a bystander can encounter. It triggers panic — the instinct to stop, to wonder if you've caused serious harm. But blood during CPR is far more common than most people realize, and understanding where it comes from changes how you respond.
Pink, frothy blood — the kind that looks almost like foam — comes from the lungs. This is pulmonary edema fluid mixing with blood, a sign of severe cardiac stress or pulmonary contusion from compressions. It doesn't mean you've ruptured something catastrophic. It means the patient's heart and lungs are under extreme stress, which is consistent with cardiac arrest.
Darker, more viscous blood often comes from the stomach. Gastric reflux during CPR can bring up blood if the patient has a pre-existing GI bleed, an ulcer, or esophageal varices. It can also come from trauma to the esophagus from forceful regurgitation.
Blood in the airway from a lung source — called hemoptysis when coughed up — can result from pulmonary contusion, which is bruising of lung tissue caused by the force of compressions. Studies suggest pulmonary contusion occurs in roughly 10 to 20 percent of CPR cases, more commonly with prolonged resuscitation efforts.
Managing blood in the airway during CPR: If you see blood or vomit in the mouth, turn the head gently to the side and let gravity drain it. Wipe the mouth with cloth if you have it. If you have a suction device — many AED kits now include simple suction tips — use it between compression cycles. Then continue CPR. The AHA CPR guidelines are clear that airway management should not interrupt compressions for more than 10 seconds.
Don't be afraid to continue rescue breathing because of blood. Seal the mouth, breathe in, watch for chest rise. If the airway is partially obstructed by fluid, you may not see good chest rise — adjust head tilt and try once more. If you still can't ventilate, hands-only CPR is better than nothing while waiting for advanced airway support.
One of the more serious but less-discussed CPR complications is pneumothorax — a collapsed lung caused by air entering the space between the lung and the chest wall. During CPR, a fractured rib can pierce the pleural membrane, allowing air to leak in and the lung to partially or fully collapse.
In most cases, a simple pneumothorax from CPR isn't immediately life-threatening beyond the cardiac arrest itself — the patient is already in extremis, and paramedics will assess for it on arrival. What is dangerous is a tension pneumothorax, where air accumulates under pressure, compresses the heart and great vessels, and prevents effective circulation. Tension pneumothorax is a true emergency — it requires immediate needle decompression — but it also presents with clinical signs (tracheal deviation, absent breath sounds on one side, severe hypotension) that trained emergency responders are equipped to recognize and treat.
For a bystander doing CPR, the response to pneumothorax is the same as the response to any other complication: keep doing CPR. You cannot diagnose or treat a pneumothorax in the field without equipment. What you can do is maintain circulation until someone who can arrives.
Pulmonary contusion is another form of CPR-related lung damage. The force of compressions bruises lung tissue, similar to the way a blunt blow to the chest would. Mild pulmonary contusion causes localized bleeding and edema within the lung; severe contusion can impair gas exchange. This is more common with prolonged CPR — resuscitations lasting over 20 minutes — and is generally managed in the ICU after return of spontaneous circulation.
Hemothorax — blood collecting in the pleural space rather than air — is less common but can occur when a fractured rib lacerates an intercostal vessel or when pulmonary contusion bleeds significantly. Like pneumothorax, it's diagnosed and treated by the medical team after the resuscitation effort.
The survival math is straightforward: a patient who survives cardiac arrest with a pneumothorax has a treatable problem. A patient who doesn't survive cardiac arrest because CPR was stopped early has no problems left to treat — in the worst sense possible. The aha cpr explicitly account for the fact that CPR-related injuries are acceptable risks of a life-saving procedure. Every guideline update has maintained this position because the data supports it consistently.
If you're providing basic CPR and you're worried about causing internal damage — don't let that worry slow your compressions. The damage you might cause is treatable. Cardiac arrest without CPR is not.
Chest depresses 2–2.4 inches. Sternum compresses heart between spine and chest wall. Blood is squeezed out into coronary arteries and aorta.
Each compression generates about 25–30% of normal cardiac output. Not enough for full function — enough to preserve brain cells and myocardium while waiting for defibrillation.
Repeated high-force compressions fatigue rib cartilage and cortical bone. In patients with reduced bone density, fractures may occur in the first 5–10 compressions.
Rib fractures, aspiration, pulmonary contusion can develop during prolonged CPR. These are secondary to the primary goal of circulation — they are managed after ROSC (return of spontaneous circulation).
Effective CPR before defibrillation significantly improves shock success. Every minute of CPR before the first shock improves survival odds.
After ROSC, imaging reveals CPR-related injuries. Rib fractures, sternal fractures, pneumothorax, hemothorax, and pulmonary contusion are assessed and treated. Most are managed non-surgically.
One of the biggest barriers to bystander CPR isn't lack of training — it's fear of legal liability. People hesitate because they're afraid that if they break someone's ribs, cause internal bleeding, or don't save the person, they'll be sued. This fear is understandable but, in practice, almost entirely unfounded.
Every U.S. state has Good Samaritan laws that protect bystanders who provide emergency assistance in good faith. These laws vary in their specifics, but their core protection is consistent: if you act reasonably and without expectation of compensation when someone's life is at risk, you're shielded from civil liability for outcomes including injury or death. Rib fractures caused by properly performed CPR are explicitly within the scope of what Good Samaritan laws cover.
Here's the practical reality: lawsuits against bystanders who performed CPR are extraordinarily rare. Legal databases have almost no cases where a bystander was successfully sued for CPR-related injuries. The legal system recognizes that someone dying of cardiac arrest needed aggressive intervention, and that a rescuer acting to save a life can't be held to the standard of a medical professional.
What could create liability — in theory — is gross negligence. CPR performed in a way that a reasonable person would recognize as harmful: jumping on someone's chest, using clearly improper technique intentionally, or performing CPR on someone who is clearly breathing and conscious. Normal CPR complications don't meet this bar by any stretch.
If you've taken a CPR renewal course or hold CPR certification, you're even better protected — evidence that you acted with training and according to established guidelines. The documentation of your training demonstrates good-faith effort, which is the core of Good Samaritan protection.
The short version: do CPR. Don't let legal fear stop you. The risk of being sued successfully for performing bystander CPR is so low it's not a meaningful factor in the decision. The risk of someone dying because no one helped is immediate and real.
The force required for effective CPR doesn't change based on the patient's vulnerability — but the likelihood of complications does. Understanding this helps you calibrate expectations when you're compressing on different types of patients.
Elderly patients and CPR broken ribs: This is where broken ribs are most common. After age 65, bone density declines significantly, and many elderly patients have additional risk factors: osteoporosis, long-term corticosteroid use, prior fractures. CPR in an 80-year-old is very likely to cause rib fractures within the first minute. The correct approach is unchanged — maintain depth and rate. The bls cpr applies to all adults regardless of age. Research on CPR in elderly patients consistently shows that despite higher complication rates, the survival benefit of full-depth CPR outweighs the benefit of reduced-force compressions.
A common instinct when performing CPR on a frail elderly person is to "go easy" — to reduce compression depth out of concern for injury. Resist that instinct. A rib fracture in a 78-year-old can heal with rest and pain management. Inadequate compressions in a cardiac arrest patient mean the brain goes without oxygen for seconds that accumulate into minutes. The brain doesn't get a chance to heal from that.
Patients with osteoporosis: Even younger patients with osteoporosis — a condition affecting roughly 10% of American adults over 50 — face elevated fracture risk during CPR. Same guidance applies: don't reduce force. Osteoporotic bone fractures at lower stress loads, which means rib fractures can occur earlier in the resuscitation and may be more extensive. Again, this is expected, documented, and doesn't change the standard of care.
Obese patients: Paradoxically, obese patients require more force to achieve the same chest compression depth, not less. Body habitus means the rescuer has to push through more tissue to reach the same 2-to-2.4-inch target depth. Fatigue sets in faster; two-rescuer CPR with frequent rotation is especially important. If you're the only rescuer on scene, compressing on an obese patient will exhaust you more quickly — even more reason to call 911 first so EMS can take over.
Children and infants: Pediatric CPR uses different technique and proportionally less force. For children (ages 1 to puberty): use one or two hands, compress 2 inches (about 1/3 the chest diameter). For infants: use two fingers, compress 1.5 inches. Rib fractures are less common in children due to greater chest wall compliance — cartilage is more flexible than bone at young ages. Aspiration risk is similar to adults; the same airway management principles apply.
In every population, the calculus is the same: the risk of under-compression (inadequate circulation, brain death, death) outweighs the risk of complications. Complications can be treated. The alternative cannot.