Inhaled Nitric Oxide Helps SARS Patients in Chinese ICUs

Jane Salodof MacNeil

May 24, 2004

May 24, 2004 (Orlando) — A Chinese clinician based in Sweden today reported promising results from a small experiment in nitric oxide inhalation as a therapy for severe cases of severe acute respiratory syndrome (SARS).

Luni Chen, MD, PhD, from Uppsala University, said inhaling 30 parts per million of nitric oxide for three to seven days improved oxygenation and allowed four of six patients to be weaned off ventilator pressure support. Four weeks later, all four had improved. Only one patient was still in an intensive care unit. One patient had died.

In contrast, four patients in an eight-patient control group were still receiving intensive care at four weeks. Two patients in this group had died.

The outcome was a surprise, according to Dr. Chen, who presented the results in a poster at the American Thoracic Society (ATS) 100th international conference. "At the beginning we could not believe what was happening," she said.

The investigators' main goal was to wean the patients off ventilator pressure support, which she described as very dangerous to patients and healthcare workers. The former were at risk of lung damage, she said, and the nursing staff were at risk of exposure to the highly contagious SARS virus.

Nitric oxide improved the oxygen index (PaO2/FiO2) from 94 to 250 mm Hg in four patients, who no longer required continuous positive airway pressure (CPAP) or bilevel ventilation (BiPAP). In one intubated patient, physicians were able to lower positive-end exploratory pressure (PEEP) without a decrease in oxygenation.

Even after nitric oxide was withdrawn, lung infiltrates were reduced in chest x-rays for all patients but one. Because the vasosuppressant properties of nitric oxide could not explain this long-term effect, Dr. Chen and colleagues suspect nitric oxide might have an effect on the SARS virus.

At a press briefing on Sunday, she and Goran Hedenstierna, MD, head of nuclear medicine at Uppsala University Hospital in Sweden, said nitric oxide killed 90% of cells infected with SARS in another in vitro study. Only 10% of untreated SARS-infected cells survived.

Dr. Chen said she did her doctoral thesis in nitric oxide and adult respiratory distress syndrome (ARDS) at Uppsala University Hospital, where she has been for five years. When the SARS epidemic struck China, she became concerned about family members in Beijing and asked her Uppsala colleagues to join her in taking the nitric oxide project to her homeland.

They visited China from May to August 2003, conducting the experiment at two intensive care units in Beijing. The patients ranged in age from 19 to 63 years.

Nan-Shan Zhong, MD, FCCP, director of the Guangzhou Institute of Respiratory Diseases in Guangzhou, China, attended the press briefing and said the use of nitric oxide was a new idea worth exploring. "We probably need more animal studies to confirm that," he said.

Dr. Zhong also gave a brief update of SARS in China. He said the country has undergone two outbreaks since the original epidemic. In December a photographer and a waitress, both exposed to civet cats, were infected. Government shutdown of wild animal markets appears to have controlled that outbreak, according to Dr. Zhong.

The most recent event originated with a laboratory exposure and has led to one or two deaths. Although the government is still addressing this event, Dr. Zhong expressed confidence that it is being controlled through a policy of early identification, report, isolation, and management. About 150 people are currently quarantined, he said.

ATS 100th International Conference: Abstract B44. Presented May 24, 2004.

Reviewed by Gary D. Vogin, MD

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