DEAR DR. ROACH: I read an article about a study the Mayo Clinic did using 20 mg tablets of sildenafil for pulmonary arterial hypertension and that it improved walking distance by 75%. Is there an upper age limit for a person using this medication for pulmonary hypertension? -- D.L.
ANSWER: Pulmonary hypertension is different from regular or systemic high blood pressure. It's not the kind that is measured with a blood pressure cuff.