PULMONARY EDEMA IN SWIMMERS

Pulmonary edema can develop with extreme exertion in cold water. Lund and colleagues discussed three cases of swimming-induced pulmonary edema that occurred in healthy men during a strenuous two-mile, cold-water ocean swim that was part of US Navy SEAL (Sea, Air, and Land) Basic Underwater Demolition training.

All three patients swam right-side down, using sidestroke and without switching sides; none of the patients aspirated seawater or immersed his head. The onset of symptoms occurred 10 minutes into the swim in one patient, after swimming for 30 minutes in another, and immediately after completing the swim in the third. Symptoms included dyspnea, coughing, confusion, and, in one case, hemoptysis.

In all patients, physical examination revealed wheezing in the right lung but not the left. Additionally, chest films taken in two patients showed infiltrates in the right lung. These same two patients also had difficulty maintaining adequate oxygen saturation without supplemental oxygen. All patients received nebulized albuterol. Symptoms resolved completely after treatment.

Pulmonary edema can occur during any form of extreme exertion, when there is both increased cardiac output and pulmonary effort. This exertional state can lead to stress pulmonary capillary failure and, subsequently, edema. Previous studies of elite athletes have revealed the presence of red blood cells in bronchoalveolar lavage fluid—suggestive of capillary fracture—after heavy exertion.

Immersion in cold water can increase central vascular volume and forearm vascular resistance. In addition, even when wetsuits are used, immersion in cold water decreases core body temperature and causes a redistribution of blood from peripheral to thoracic vessels. The increase in sympathetic activity that accompanies immersion can cause peripheral vasoconstriction.

Swimming-induced pulmonary edema usually resolves with removal from the water, removal of cold clothing, a warm environment, supplemental oxygen, and a ß2-agonist. The authors recommended that swimmers switch sides periodically to rest muscle groups.

Lund KL, Mahon RT, Tanen DA, Bakhda S. Swimming-induced pulmonary edema. Ann Emerg Med. 2003;41:251-256.

INHALED STEROIDS INCREASE HIP FRACTURE RISK

A recent study has found a dose-response relationship between inhaled corticosteroids and hip fracture. Hubbard et al used data from the General Practice Research Database to identify patients who had hip fractures between August 1, 1987, and November 22, 1999. Two age- and sex-matched controls were assigned to each patient. All prescriptions for inhaled corticosteroids were recorded, and the mean daily dose for each patient was calculated. The relationship between ever having a prescription for inhaled corticosteroids and hip fracture was determined using logistic regression.

The study included 16,341 cases of hip fracture. Three percent of patients had asthma, 3% had chronic obstructive pulmonary disease (COPD), and 2% had both. There were 46,765 prescriptions for inhaled corticosteroids in both patients and controls; the median daily dose was 249 mg. Eight percent of patients had been prescribed an inhaled corticosteroid, compared with 6% of controls. Patients with asthma and COPD had a median daily dose of inhaled corticosteroids of 360 mg. A total of 52% of inhaled corticosteroid users also received at least one prescription for an oral corticosteroid.

While there was a small increase in the risk of hip fracture with inhaled corticosteroid use, that risk increased with the dose of the steroid, and the test for trend was statistically significant. While this analysis did not take into consideration lung function or physical activity, which may have influenced the results, the authors maintained that the increase in fracture risk is likely to be—at least in part—due to a direct effect of inhaled corticosteroids on bone metabolism.

The risk of hip fracture can be influenced by other variables, including having a history of falls, smoking, body weight, having cerebrovascular or psychiatric illness, and using laxatives, hypnotics, antipsychotics, tricyclic antidepressants, or opioid analgesics. Hip fracture was reduced in those who were even slightly overweight.

The authors acknowledged that inhaled corticosteroids have substantial benefits but added that patients with asthma and COPD should not take higher doses than necessary to control airflow obstruction.

Hubbard RB, Smith CJP, Smeeth L, et al. Inhaled corticosteroids and hip fracture: a population-based case-control study. Am J Respir Crit Care Med. 2002;166:1563-1566.

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