A heat and moisture mask attenuates cardiovascular stress during cold air exposure.

BACKGROUND

Exposure to cold has been shown to cause cardiovascular stress and increased morbidity and mortality. Inhalation of cold, dry air can increase blood pressure and induce myocardial ischemia, particularly in people with preexisting hypertensive cardiovascular disease. Face masks that can warm and humidify inhaled cold air may reduce these cold air pressor effects.

METHOD: We compared blood pressure measurements using a heat and moisture exchange mask (HME), a placebo mask (PL), and no mask (NM) in 53 patients with hypertension exposed to a cold chamber environment at -5°C for 1 h. Blood pressure and heart rate were recorded at baseline, and at 15 min intervals from 0 to 60 min of chamber exposure. All patients were taking antihypertensive medications with drug and dosage determined by their own physicians. Data were analyzed by a one-way analysis of variance test with repeated measures, and significant interactions were analyzed by Fisher's least significant differences tests. A post hoc subgroup analysis for the effect of age was performed using Wilcoxon matched-pair rank tests.

RESULTS

Wearing the HME resulted in significantly lower systolic and mean arterial blood pressures than the PL and NM conditions. Diastolic blood pressures were significantly lower for the HME than the NM, but not the PL condition.

CONCLUSION

Subgroup analyses suggested that the effect of the HME in mitigating systolic blood pressure increase from inhalation of cold air was significantly greater for patients aged 60 years or over than for those under 60 years.