context: End-stage, or stage 4, COPD is the final stage of chronic obstructive pulmonary disease. Most people reach it after years of living with the disease and the lung damage it causes. As a result, your quality of life is low. You'll have frequent exacerbations, or flares -- one of which could be fatal. To figure out if you're in stage 4, your doctor will do a lung test called spirometry. It shows how well your lungs work. It measures: Forced vital capacity ( FVC): The largest amount of air you can exhale forcefully after taking in as big a breath as you can. Forced expiratory volume ( FEV1): How much air you can force from your lungs in one second. You're in stage 4 when: FEV1 / FVC is less than 70% FEV1 is less than 30% COPD affects everyone differently. With proper treatment, the disease doesn't have to limit how long you live, even if it's severe COPD. Exercise safely. Be on the lookout for -- and act on -- warning signs of an acute flare, or exacerbation. Things that play a role in how well you'll do include: Severity of your COPD Smoking Low body mass index Frequent acute flares If you go to the hospital, your short-term outlook depends more on how severe the flare is than how severe your COPD is. In the long run, though, the severity of your COPD is what matters, along with related conditions like lung cancer, cardiovascular disease, sleep apnea, metabolic syndrome, and diabetes, among others. Many of the symptoms you had in earlier stages, like coughing, mucus, shortness of breath, and tiredness, are likely to get worse. Just breathing takes a lot of effort. You might feel out of breath without doing much of anything. Flare-ups may happen more often, and they tend to be more severe. You may also get a condition called chronic respiratory failure. This is when not enough oxygen moves from your lungs into your blood, or when your lungs don't take enough carbon dioxide out of your blood. Sometimes, both happen. Other symptoms of end-stage COPD include: Crackling sound as you start to breathe in Barrel chest Constant wheezing Being out of breath for a very long time Delirium Irregular heartbeat Fast resting heartbeat Weight loss High blood pressure in the artery that goes from the heart to the lungs (pulmonary hypertension) As with stage 3, it gets harder to keep up with eating well and exercising, which boost your strength and energy levels. The more severe your COPD, the more likely you are to get infections. You may get a few tests: Spirometery: In Stage 4 COPD, the FEV1 is less than 30%. You might still have advanced COPD if your FEV1 is higher. That's why your doctor may also check for chronic respiratory failure with these: Arterial blood gas test: This checks the oxygen and carbon dioxide levels in your blood. Pulse oximetry test: A small sensor on your finger or ear tells you how much oxygen you have in your blood. Your doctor will use the same treatments from earlier stages, though you may need different doses, combinations, or need some of them more often: Short-term and long-term bronchodilators Steroids and antibiotics Pulmonary rehab plan Oxygen therapy Surgery may also be an option. You'd get it only if drugs don't work for you. And even then, it only helps a small number of people. There are a few different types: Bullectomy: COPD can make the tiny air sacs in your lungs get much larger. When that happens, doctors call them bullae. It's not too common, but they can grow big enough to get in the way of your breathing. A surgeon removes them to help you breathe more easily. Lung volume reduction surgery: For some people, this operation to remove the top part of your lungs improves breathing and quality of life. To get it, you need to have a strong heart and enough healthy lung tissue. You also need to quit smoking and show that you can stick to your pulmonary rehab plan. Lung transplant: This is when you get a healthy lung from a donor. It has serious risks. For instance, your body may reject the new lung. Doctors typically suggest this surgery only for people who have a lot of lung damage and no other health problems. You may want to talk to your doctor about palliative care, which focuses on quality of life and easing any pain or other symptoms. You work with a team of doctors, nurses, and social workers to: Set goals for what you want from your care Help you make medical decisions based on those goals Get support for your body, mind, and emotions, such as doing breath exercises and dealing with anxiety Address the needs of your family members and caregivers It's also good to talk with your friends, family, and medical team about what you want from end-of-life care. It may not be an easy topic to open up about, but studies show that the sooner you do, the better care you'll get. That can be comforting for both you and your loved ones.