An eerie symptom can manifest itself when a dying patient is close to the end of their life, a doctor says. Dr Paulien Moyaert, a Nuclear Medicine Resident and academic from Belgium shares explainers on her YouTube channel on a wide variety of medical topics, discussing thinks like how certain drugs and parts of the body work.

In a recent video, she addressed the phenomemon of a breathing sound patients approaching death may make, sometimes described as a “death rattle”. According to Dr Moyaert: “A person usually lives for 23 hours after the death rattle begins,” adding: “With each breath the person may make a moaning, snoring or rattling sound”.

She said: “This occurs because as consciousness decreases, patients lose their ability to swallow and clear oral secretions. Air moves over these pooled secretions resulting in noising breathing.”

She continued: “Some people say that the death rattle is the lungs’ attempt to breathe through a layer of saliva,” she added.

However, Dr Moyaert says it’s “important to know that this is not distressing for the patient, because they are non-responsive and deeply asleep at this point.”

Though she acknowleges that it “sounds terrible”, and can be difficult for families to hear. For this reason, medics “often give drugs to dry up the airways and soften the death rattle,” she explained, adding that its for the dying person’s loved ones rather than the patient.

She said repositioning the patient so they’re “turned to their side with their head slightly elevated may also help”.

The NHS website explains that breathing can become “more noisy” due to “the build-up of mucus”.

“The body naturally produces mucus in your breathing system, including the lungs and nasal passages,” the health service explains on its website. “When you’re healthy, this mucus is removed through coughing.

“When you’re dying and no longer moving around, the mucus can build up and cause a rattling sound when you breathe.”

The NHS explains various changes that can take place during what’s called the “terminal phase”, including becoming drowsy, not wanting to eat or drink, changes in breathing, confusion and hullucinations, and having cold hands and feet.

According to end of life charity Marie Curie, most people who experience this noisy breathing in the last days and hours of life “will die within a few days”.

However, it adds that: “Everyone is different – some people will live longer and others will die more quickly.”

It advises loved ones upset or concerned about the symptom to “speak to their doctor, nurse or care home staff”.

The NHS lists various resources for information about the last hours and days of life, including advice for carers and family.

You can find them here.