Do Tien Hai, head of the Department of Maxillofacial Plastic and Reconstructive Microsurgery at the National Hospital of Odonto-Stomatology in Ho Chi Minh City, provided the medical assistance on Vietnam Airlines flight VN99 from San Francisco to HCMC on Aug. 5.

The American man in his late 20s, seated in the business class cabin, began vomiting food mixed with a significant amount of fresh blood more than an hour into the flight.

"The patient was very panicked at the time, and the scene was quite chaotic because he had just eaten, and he vomited a large amount of food and blood," Hai told VnExpress on Aug. 12.

Hai, who was returning from a month-long professional exchange at Johns Hopkins and Wake Forest hospitals in the U.S., volunteered when the cabin crew announced a request for medical assistance.

When he found out he was the only doctor on board, he immediately approached the distressed passenger. He collaborated with an American nurse, who was also a passenger, to provide treatment.

Doctor Do Tien Hai during his professional exchange at Johns Hopkins Hospital in the U.S. Photo courtesy of Hai

Initially, Hai considered the possibility of gastrointestinal bleeding.

However, when asked about abdominal pain or other unusual gastrointestinal symptoms, the passenger reported having none.

The man pointed to his right nostril, explaining that blood was flowing from his nose into his mouth while pinching his nose to stop the bleeding.

Based on these symptoms, Hai determined the blood in the vomit most likely originated from a severe nosebleed.

He suspected a rupture of vessels in Kiesselbach's area, a region near the front of the nasal cavity where many small blood vessels are concentrated.

According to the doctor, changes in cabin pressure as an aircraft climbs can exacerbate bleeding in this area.

Blood flowing down the throat can then be swallowed into the stomach, triggering nausea and vomiting, particularly if the passenger has recently eaten.

The medical duo treated the patient by applying continuous pressure to the nostril, monitoring his pulse and blood pressure, and applying a cold compress.

After approximately 30 minutes, the bleeding ceased, and his vital signs stabilized.

"Cold temperatures help constrict the blood vessels at the bleeding site. Combining a cold compress with pressure helps control the bleeding," the doctor explained.

The flight crew then consulted with the Vietnamese doctor on whether the plane needed to divert back to San Francisco to transport the passenger to an emergency facility.

Given that the bleeding had stopped and the patient's pulse and blood pressure remained stable post-treatment, Hai and the cabin crew decided against turning the plane around and allowed the flight to proceed.

Flight staff later assisted the patient in cleaning himself, changing clothes, and sanitizing his seating area.

Hai and the nurse continued to monitor the man, applying a cold compress to his nose until his condition fully stabilized.

Hai noted that when a person experiences heavy nosebleeds, their medical history should be assessed to rule out underlying conditions that increase the risk of bleeding, such as diseases affecting the nose or nasopharynx.

In this instance, the passenger reported no relevant medical history.

The flight landed safely at Tan Son Nhat International Airport in Ho Chi Minh City in the early hours of Aug. 7.

The American passenger, whose condition remained stable, departed the plane and thanked his caregivers.

When he met Hai again in the immigration processing area, he said, "Vietnamese are so kind."

The handwritten letter sent by a Vietnam Airlines flight crew to doctor Do Tien Hai for assisting an American passenger on board. Photo courtesy of Hai

Hai advises anyone who develops a sudden nosebleed while flying to sit slightly forward, use their fingers to apply pressure to the soft part of the nose at the bleeding site, and apply a cold compress if possible.

He warned against tilting the head backward, as this allows blood to flow down the throat and into the stomach, causing nausea and vomiting.

However, if the bleeding persists, is exceptionally heavy, recurs, or is accompanied by symptoms such as dizziness, fatigue, or difficulty breathing, the patient must be assessed by medical personnel.

Individuals with conditions affecting the nose or nasopharynx, or those with underlying illnesses that increase bleeding risks, should exercise heightened caution if such symptoms arise.

Following the incident, the cabin crew sent Hai a formal letter thanking him for his assistance.

"I am happy that I was able to contribute to keeping the passenger safe and helping the flight continue smoothly. An incident like this also adds a meaningful color to the picture of my life," Hai said.