Discover - July/August 2011

pressure. Using my ;ngers on the pulse at her wrist, I could palpate her systolic pressure. (;e top number in any blood pressure reading, systolic measures the maximum pressure of the waves generated by the beating heart.) Normal systolic pressure is ;;;. Below ;; is very low; less than ;; and you’re in shock. Hers was ;;.

I immediately had my patient lie down on the exam table to improve circulation to her brain and rechecked her blood pressure. It was still only ;;. During prolonged shock, circulation is inadequate to deliver oxygen to your tissues for hours on end, and multiple organs can shut down. It is a life-threatening emergency. I told my sta; to call ;;;.

CORBIS

;; ;;;; ;;;;; ;;; ;;;; ;; ;;; patient was in anaphylactic shock, a severe allergic reaction mediated by the body’s immune system. Reactions to allergic triggers may be mild or may rapidly progress to respiratory or cardiovascular collapse and death.

Sometimes a reaction evolves over hours. ;e allergic triggers are usually food (especially nuts and shell;sh, but also peppers), medications, or insect stings. ;e symptoms typically involve the skin (hives, ;ushing, itching) and may also include the respiratory system (wheezing with respiratory failure) and the cardiovascular system (low blood pressure and shock).

When an anaphylactic reaction hits, a ;ood of chemicals, primarily histamine, are dumped into the bloodstream. Produced by specialized blood cells that respond to injury, infection, or allergic triggers, histamine is normally released locally in tissues as part of the body’s defense mechanism. But during anaphylaxis this response goes haywire. When large amounts of histamine pour into the circulatory system, blood vessels lose their elastic tone and get leaky. Floppy, leaky blood vessels fail to squeeze down when you are upright, so blood pools in your extremities instead of ;owing back to the heart.

H. Lee Kagan
is an internist in
Los Angeles. The
cases described
in Vital Signs
are real, but names
and certain
details have been
changed.

Cardiac output falls and blood pressure drops, leading to shock. ;at’s why my patient fainted. In severe reactions, patients may experience shock even while lying down.

;e combination of tingling lips, which can be part of an allergic response, and dangerously low blood pressure is what tipped me o; to the anaphylaxis. It’s a diagnosis made purely on clinical grounds; there is no time to wait for con;rmatory blood tests, since it can be fatal if not treated promptly. Although there are other causes of shock, if there is any reasonable suspicion of anaphylaxis, it’s always better to treat ;rst and ask questions later.

I shoved some pillows under my patient’s legs to get them elevated, hoping to increase blood return to her heart and brain. I injected a dose of epinephrine (adrenaline) from our o;ce emergency kit into her thigh muscle. Adrenaline quickly restores tone to the blood vessels and ramps up the strength and speed of cardiac action. Next I started an ;; and ;icked the control valve to wide open so that saline would run into her vein as quickly as possible and help restore the volume of liquid circulating through her arteries. My nurse placed tubing under the patient’s nose to maximize the amount of oxygen her blood would deliver to her tissues.

By the time the paramedics had her on their gurney ready to be transported to the ;;, my patient’s blood pressure was up to ;;. Two hours later, the ;; attending physician called me to say that her pressure was normal and she was doing ;ne. Doctors planned to keep her there for observation for the rest of the day to be sure the reaction had blown over.

So was it the sweet peppers that had started this nearly lethal chain of events? Perhaps, but only allergy testing could tell for sure. ;e patient would need to see an allergist and would also need to carry an emergency dose of injectable epinephrine at all times in case of another reaction. In the meantime, the doctors advised her to hold the peppers.