Last Sunday, Huu Nghi Hospital in Hanoi received a 73-year-old woman with a history of chronic obstructive pulmonary disease, heart failure, and adrenal insufficiency.
She was taken to hospital suffering respiratory difficulties.
The patient was put on a ventilator until Wednesday when she could breathe independently.
Every time it was cold, she had difficulty breathing due to a worsening lung condition. The day she fell ill, the temperature in the capital dropped to below 10 degrees Celsius.
The elderly woman is among tens of patients that have been admitted to Huu Nghi Hospital in the past few days following cold weather in Hanoi.
Nguyen Dang Khiem, head of the Emergency Department at the hospital, said it had received 30-40 patients per day over the past week and that most of them are seniors, up 20-30 percent compared to normal.
Of the patients, 60 percent have a cardiovascular disease and 30 percent, a respiratory equivalent.
Since Feb. 18 a mass of cold air combined with rains have caused the coldest spell this winter in northern Vietnam. Temperatures in some places dropped below zero, causing frost to cover the trees and ground.
At 6 a.m. Wednesday almost all 25 northern localities recorded temperatures of below 11 degrees Celsius, according to the National Center for Hydro-Meteorological Forecasting (NCHMF).
In Quang Ninh Province which borders China, doctors at Bai Chay Hospital said the number of hospitalizations due to respiratory disease had increased by 40 percent in recent days. Most patients include the elderly and young children, especially those with chronic respiratory diseases like bronchial asthma, chronic obstructive pulmonary disease, and bronchiectasis.
According to doctors, cold weather and high humidity provide a suitable environment for respiratory viruses to thrive.
Seniors who already have chronic respiratory diseases tend to suffer worse conditions if infected with those viruses because the low temperature normally causes constriction of blood vessels, causing overload for their circulatory system.
As a result, patients often suffered hypertension, heart failure, and possibly a stroke due to sudden and excessive constriction of the vascular system.
At E Hospital in Hanoi, the number of patients hospitalized for strokes has increased by 10-15 percent since early February and almost all are elderly people.
Doctor Pham Xuan Hieu, head of the hospital's Emergency Department, said the sudden change in temperature leaves a huge impact on the brain and heart vessels of the elderly, which could lead to stroke.
If the patients are not taken to hospital in time, they could die or suffer serious sequelae, such as paralysis and disability.
The same situation has been reported at 108 Military Central Hospital in Hanoi, which has seen the number of elderly stroke patients increase two-three times in recent days.
Ta Duc Thao, a doctor in the Stroke Department, said the cold weather does not directly cause strokes but the low temperature would cause a sudden increase in blood pressure and blood vessels to constrict.
The NCHMF said the cold spell could last until Feb. 24. It added north and north-central regions would experience temperatures of 7-10 degrees in the plains and zero to six in the mountains on Thursday.
Conditions have killed more than 2,999 cattle in the north since Feb. 19, with nearly 2,000 dying on Tuesday alone, according to the National Steering Committee for Natural Disaster Prevention and Control.