NEW YORK – American Airlines on Monday insisted it tried to help a passenger who died after complaining she couldn’t breathe, and disputed the account of a relative who said that she was denied oxygen and that medical devices failed.

The airline said the oxygen tanks and a defibrillator were working and noted that several medical professionals on the flight, including a doctor, tried to save passenger Carine Desir, 44, who had heart disease.

“American Airlines, after investigation, has determined that oxygen was administered on the aircraft, and it was working, and the defibrillator was applied as well,” airline spokesman Charley Wilson said Monday.

Desir had complained of not feeling well and being very thirsty on the Friday flight home from Port-au-Prince, Haiti, after she ate a meal, according to Antonio Oliver, a cousin who was traveling with her and her brother, Joel Desir. A flight attendant gave her water, he said.

A few minutes later, Desir said she was having “trouble breathing” and asked for oxygen, but a flight attendant twice refused her request, Oliver said.

“Don’t let me die,” he recalled her saying.

He said other passengers aboard Flight 896 became agitated over the situation, and the flight attendant, apparently after phone consultation with the cockpit, tried to administer oxygen from a portable tank and mask, but the tank was empty.

Oliver said two doctors and two nurses were aboard and tried to administer oxygen from a second tank, which also was empty. Desir was placed on the floor, and a nurse tried CPR, Oliver said. A defibrillator, which he called a “box,” also was applied but didn’t function effectively, he said.

Oliver said he then asked for the plane to “land right away so I can get her to a hospital,” and the pilot agreed to divert to Miami, 45 minutes away. But during that time Desir collapsed and died, Oliver said.

“Her last words were, ‘I cannot breathe,'” he said.

There were 12 oxygen tanks on the plane and the crew checked them before the flight took off to make sure they were working, Wilson said. He said at least two were used on Desir.

The Federal Aviation Administration requires commercial flights to carry no fewer than two oxygen dispensers. The main goal of the rule is to have oxygen available in the event of a rapid cabin decompression, but it can also be used for other emergencies. It is up to the airlines to maintain the canisters.

Flight attendants are trained not to automatically give oxygen to every passenger who requests it but instead use airline criteria to judge when it’s needed, said Leslie Mayo, a spokeswoman for the union representing American’s attendants.

Wilson said Desir’s cousin flagged down a flight attendant and said the woman had diabetes and needed oxygen. “The flight attendant responded, ‘OK, but we usually don’t need to treat diabetes with oxygen, but let me check anyway and get back to you.'”

Wilson said the employee spoke with another flight attendant, and both went to Desir within one to three minutes.

“By that time the situation was worsening, and they immediately began administering oxygen,” he said.

Wilson said the defibrillator was used but that the machine indicated Desir’s heartbeat was too weak to activate the unit.

An automated external defibrillator delivers an electric shock to try to restore a normal heart rhythm if a a particular type of irregular heart beat is detected. The machines cannot help in all cases.

Wilson said three flight attendants helped Desir, but “stepped back” after doctors and nurses on the flight began to help her.

“Our crew acted very admirably. They did what they were trained to do, and the equipment was working,” he said.

Desir was pronounced dead by one of the doctors, Joel Shulkin, and the flight continued to John F. Kennedy International Airport, without stopping in Miami. The woman’s body was moved to the floor of the first-class section and covered with a blanket, Oliver said.

Desir died of complications from heart disease and diabetes, said Ellen Borakove, a spokeswoman for the medical examiner’s office.

Shulkin, through his attorney, Justin Nadeau, declined to comment on the incident.

FAA spokeswoman Alison Duquette said the agency was closely following the details of the incident.