Which of the following drugs is contraindicated in a patient with glaucoma who is scheduled for surgery?

KPSC Staff Nurse - 2016

Pharmacology

Medium

Appeared in: KPSC Staff Nurse - 2016

Explanation

Atropine is a potent anticholinergic (muscarinic antagonist) drug used pre-operatively to reduce secretions and prevent bradycardia.
Its significant side effect is mydriasis (pupil dilation).
In patients with narrow-angle glaucoma, mydriasis causes the iris to bunch up and physically obstruct the trabecular meshwork, the eye's drainage system.
This blockage of aqueous humor outflow leads to a rapid, severe increase in intraocular pressure (IOP), precipitating an acute angle-closure attack, which is a medical emergency.

Option A: Demerol (meperidine) is an opioid analgesic. Opioids typically cause miosis (pupil constriction), which does not obstruct aqueous outflow and is therefore not contraindicated in glaucoma.
Option C: Valium (diazepam) is a benzodiazepine used for its anxiolytic and sedative properties. It has minimal to no effect on pupil size or intraocular pressure, making it safe for patients with glaucoma.
Option D: Phenergan (promethazine) is an antihistamine with antiemetic and sedative properties. While it possesses some weak anticholinergic effects and should be used with caution, it is not as potent as atropine. Atropine is the absolute and most dangerous contraindication among the choices.

Clinical Relevance

Nursing practice connection: Use the key finding related to Pharmacological contraindications in pre-operative care for patients with glaucoma to guide bedside assessment, documentation, and the next nursing action.
A key nursing responsibility in pre-operative care is to perform a thorough medication reconciliation and health history review, specifically screening for conditions like glaucoma.
Nurses must be vigilant for signs of an acute glaucoma attack post-medication administration: sudden severe eye pain, blurred vision, seeing halos around lights, headache, and nausea/vomiting. These are signs of a medical emergency requiring immediate intervention.
What if the patient had open-angle glaucoma? While the risk is lower than in narrow-angle glaucoma, potent anticholinergics are still used cautiously as they can slightly decrease outflow facility. However, it is not an absolute contraindication as it is in narrow-angle glaucoma.

How to Approach the Question

First, identify the key elements of the question: a patient with glaucoma is scheduled for surgery, and you need to find the contraindicated drug.
Recall the basic pathophysiology of glaucoma: it involves increased intraocular pressure (IOP) due to problems with aqueous humor drainage.
Focus on narrow-angle glaucoma, as it is most susceptible to acute attacks from medications.
Analyze each drug option based on its pharmacological class and effect on the eye, specifically the pupil.
Drugs that cause mydriasis (pupil dilation) are dangerous in narrow-angle glaucoma because they can physically block the drainage angle.
Evaluate the options: Atropine is a classic anticholinergic known for causing significant mydriasis. Meperidine (opioid) causes miosis. Diazepam (benzo) has little effect. Promethazine has weak anticholinergic effects. Therefore, atropine poses the greatest and most direct risk.

Concept Tested & Keywords

Concept Tested: Pharmacological contraindications in pre-operative care for patients with glaucoma.
Stem keywords: drug, contraindicated, glaucoma, surgery
Lead-in keywords: Which of the following
Clinical cues: Patient with glaucoma
Clinical cues: Scheduled for surgery

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