Mayo Clinic physicians look for cause of 'hot tub lung'

ROCHESTER, Minn. -- As the number of hot tubs in the United States continues to grow, physicians are likely to see an increase in "hot tub lung" cases. Mayo Clinic researchers in the November issue of Mayo Clinic Proceedings present two cases and offer their conclusions as to the cause of the patients' lung inflammation.

The two patients with respiratory problems showed improvement with the use of corticosteroids and discontinuing the use of the hot tub, the researchers report. The researchers suspect that mycobacteria caused an inflammation of the patients' lungs that was brought about by use of a hot tub.

"We recommend that physicians maintain a high index of suspicion for hot tub lung and include questions about hot tub use in their routine review of symptoms in patients with respiratory problems," said Otis Rickman, D.O., of the Mayo Clinic Division of Pulmonary and Critical Care and Internal Medicine and the chief author of the report.

Mayo Clinic researchers said past reports have incompletely characterized the disease associated with Mycobacterium avium complex (MAC) growing in hot tub water. It is unclear from the reports whether this disorder is an infection or hypersensitivity pneumonitis. The researchers also noted that all of the reported cases of hot tub lung have been associated with a hot tub indoors at a personal residence.

Hot tubs provide an excellent growth environment for MAC; the warm temperature promotes growth and owners frequently do not clean them or change filters as often as recommended. At temperatures higher than 84 degrees Fahrenheit, chlorine loses much of its disinfectant properties. The researchers note that the steam and bubbles generated efficiently aerosolize the organism, facilitating easy inhalation.

Contributing with Dr. Rickman in the study were Jay Ryu, M.D., and Sanjay Kalra, M.D., of the Division of Pulmonary and Critical Care Medicine and Internal Medicine; and Mary Fidler, M.D., of the Mayo Clinic Department of Laboratory Medicine and Pathology.

Mayo Clinic Proceedings is a peer-reviewed and indexed general internal medicine journal, published for more than 75 years by Mayo Foundation, with a circulation of 130,000 nationally and internationally.

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