to the editor: Peak expiratory flow is a convenient tool for following and assessing patients with asthma. Patients are instructed in peak expiratory flow measurement as a means of home monitoring and adjustment of therapy, and it is considered to be safe, inexpensive and effective. However, at least two deaths caused by respiratory arrest following measurement of peak expiratory flow have been reported in young patients,¹ both of which occurred during an acute asthmatic attack. We recently saw a patient suffer respiratory arrest in the office following measurement of peak expiratory flow; however, the patient was not having an acute asthmatic attack at the time, but was instead in the office for a routine follow-up visit.

The patient, a 41-year-old man, is well known in our office. Almost 10 years earlier, he was treated for a positive purified protein derivative test with six months of isoniazid therapy, but he has no other medical problems besides asthma. He was in the office for routine follow-up and adjustment of medications. His vital signs were blood pressure 110/79 mm Hg, pulse rate 76 per minute and oxygen saturation 90 percent on room air. He was doing well, in fact better than his usual baseline, and his physician measured his peak expiratory flow in the office. It was 300 mL, significantly better than his usual measurements. She stepped out of the examination room to verify dosages of medication, when she heard him call for help. She immediately returned to the examination room where she witnessed the patient suffering respiratory arrest and progressing to cardiac arrest. Cardiopulmonary resuscitation, including chest compressions and medications, was required to resuscitate him. He was transferred to the intensive care unit, where he did well, and was subsequently discharged without sequelae.

We would caution physicians to be aware that measurement of peak expiratory flow, although generally considered safe, can trigger bronchospasm and the complications of respiratory or cardiac arrest.