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Zorluk: Çok zorInitial Stabilization and Triage

A 64-year-old woman is evaluated in the emergency department for severe dizziness and a rapidly spreading rash. Thirty minutes ago, she was given a dose of intravenous ampicillin-sulbactam for a suspected soft tissue infection of her forearm. Shortly after the infusion, she developed diffuse pruritus, a sensation of throat fullness, and profound lightheadedness. Her past medical history is significant for essential hypertension, diet-controlled type 2 diabetes mellitus, open-angle glaucoma, and migraine headaches. Her daily medications include lisinopril, topical timolol ophthalmic drops, and as-needed sumatriptan.

On arrival, her blood pressure is 65/38 mmHg, heart rate is 46/min, respiratory rate is 24/min, and oxygen saturation is 94% on room air. Physical examination reveals an agitated and flushed woman with diffuse urticaria over her trunk and extremities. Lung auscultation reveals mild, scattered expiratory wheezes bilaterally with good air movement. There is no stridor, and her oropharynx is clear without visible angioedema.

Nursing staff immediately place two large-bore intravenous lines and initiate a rapid infusion of normal saline. The physician promptly administers 0.5 mg of intramuscular epinephrine into the anterolateral thigh. Five minutes later, the patient's blood pressure is 60/35 mmHg and her heart rate is 44/min. A second dose of intramuscular epinephrine is administered, but her hemodynamic status remains unimproved after another five minutes.

Which of the following is the single most urgent initial step in the ongoing stabilization of this patient?

  1. Intravenous administration of glucagonCevap
  2. B
    Endotracheal intubation with rapid sequence induction
  3. C
    Intravenous administration of hydrocortisone and diphenhydramine
  4. D
    Intravenous administration of milrinone
  5. E
    Intravenous administration of atropine sulfate

Cevap

The correct answer is intravenous administration of glucagon.
The correct answer is the intravenous administration of glucagon. This patient is experiencing anaphylactic shock triggered by ampicillin-sulbactam. Despite receiving fluids and two doses of epinephrine, she remains in profound shock with paradoxical bradycardia. This presentation is classic for anaphylaxis in a patient with systemic beta-blockade. Timolol ophthalmic drops, used for glaucoma, drain into the nasolacrimal duct and are absorbed directly into the systemic circulation, bypassing first-pass hepatic metabolism and causing significant non-selective beta-blockade. Because her beta-receptors are blocked, epinephrine cannot induce the necessary chronotropic, inotropic, or bronchodilatory effects. Glucagon is the antidote of choice in this scenario because it binds to distinct glucagon receptors on the myocardium, directly stimulating adenylate cyclase to produce cyclic AMP (cAMP) independently of the beta-adrenergic receptor, thereby restoring cardiac output and stabilizing the patient.

Adım Adım Çözüm

1
Diagnose the primary acute condition.
The patient has anaphylactic shock, evidenced by sudden hypotension, urticaria, and wheezing shortly after receiving an intravenous antibiotic.
Recognizing the distributive shock state sets the foundation for standard resuscitation algorithms.
2
Analyze the response to standard initial therapy.
The patient has refractory shock and paradoxical bradycardia (HR 44-46/min) despite receiving two appropriate doses of intramuscular epinephrine and intravenous fluids.
Anaphylactic shock typically presents with compensatory tachycardia. Bradycardia in this setting suggests an underlying medication effect interfering with the endogenous and exogenous catecholamine response.
3
Correlate clinical findings with the patient's medication history.
The patient takes topical timolol ophthalmic drops for glaucoma. Systemic absorption via the nasolacrimal duct causes significant systemic beta-blockade.
Beta-blockade prevents epinephrine from binding to beta-1 and beta-2 receptors, severely blunting its chronotropic, inotropic, and bronchodilatory effects, rendering standard anaphylaxis therapy ineffective.
4
Select the appropriate targeted pharmacological rescue therapy.
Intravenous glucagon is selected.
Glucagon acts on distinct myocardial glucagon receptors, directly activating adenylate cyclase to increase intracellular cAMP. This bypasses the blocked beta-receptors, restoring cardiac contractility and heart rate to stabilize hemodynamics.

Anahtar Kavram

Patients with systemic beta-blockade (including from ophthalmic drops like timolol) who develop anaphylaxis often present with paradoxical bradycardia and severe hypotension that is refractory to standard epinephrine. The required stabilization step is the administration of intravenous glucagon to bypass the blocked beta-receptors.
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Initial Stabilization and Triage

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