GUIRITAN, ABIGAYLE THERESE R. SGD AUTONOMICS

2MEDB SUBSEC 5 SEPTEMBER 5, 2015

CASE:

A 72 year old male patient was admitted to the emergency room because of eye pain, blurring of vision, and difficulty in depth perception. Review of systems revealed that the patient has narrow- angle glaucoma. Review of current medications revealed that the patient has colds for which the patient was prescribed a nasal decongestant, oral phenylephrine at the outpatient department.

1. What is the patient’s chief complaint? What could be its cause?

Chief complaint: eye pain, blurring of vision, and difficulty in depth perception

Cause: prescription of oral phenylephrine for the nasal congestion of the patient.

PHENYLEPHRINE

- DRUG CLASSo Alpha adrenergic agonisto Nasal decongestanto Opthalmic vasoconstrictor or mydriatico Sympathomimetic amineo Vasopressor

- MECHANISM OF ACTION:o Powerful postsynaptic alpha-adrenergic receptor stimulant that causes vasoconstriction

and increased systolic and diastolic BP with little effect on the beta receptors of the heart. Topical application causes vasoconstriction of the mucous membranes, which in turn relieves pressure and promotes drainage of the nasal passages. Topical ophthalmic application causes contraction of the dilator muscles of the pupil (mydriasis), vasoconstriction, and increase outflow of aqueous humor.

2. What autonomic receptor is affected by the nasal decongestant?- Alpha adrenergic receptor; selective alpha 1 agonist

3. What is the relationship of the drug phenylephrine to the patient’s chief complaint? Is it preventable?

- Sympathomimetic agents can induce transient mydriasis via stimulation of alpha-1 adrenergic receptors. In patients with anatomically narrow angles or narrow-angle glaucoma, pupillary dilation can provoke an acute attack. In patients with other forms of glaucoma, mydriasis may occasionally increase intraocular pressure. Therapy with sympathomimetic agents should be administered cautiously in patients with or predisposed to glaucoma, particularly narrow-angle glaucoma.

- Phenylephrine causes simultaneous contraction of the sphincter and dilator muscles of the iris in opposite directions pupil- block angle closure triggers an ↑IOP in an at risk eye4. What other systemic symptoms might the patient experience?

Systemic administration:

CNS: Fear, anxiety, tenseness, restlessness, headache, light-headedness, dizziness, drowsiness, tremor, insomnia, hallucinations, psychological disturbances, seizures, CNS depression, weakness, blurred vision, ocular irritation, tearing, photophobia, symptoms of paranoid schizophrenia

CV: Cardiac arrhythmias

GI: Nausea, vomiting, anorexia

GU: Constriction of renal blood vessels and decreased urine formation (initial parenteral administration), dysuria, vesical sphincter spasm resulting in difficult and painful urination, urinary retention in males with prostatism

5. What must be done in this patient?

Prehospital care:

The patient should be brought to the hospital in an expeditious manner to have the IOP reduced. The px should remain in a supine position as long as possible (to prevent further increase of IOP).

Emergency department care:

Medications must be given to reverse the effects of the drug phenylephrine that caused his narrow angle glaucoma.

6. What medication(s) may be given to alleviate the patient’s symptoms?Acetazolamide

a. Antiglaucoma drugb. MOA- inhibits the enzyme carbonic anhydrase. This action decreases AH formation in

the eye(↓ IOP)Analgesic

c. For pain (extraocular manifestation); this can drastically increase an already elevated IOP.

Pilocarpined. Parasympathomimetic druge. Miotic that leads to the opening of the angle.

Hyperosmotic agent (Mannitol)f. Creates an osmotic gradient in the eye between

plasma and ocular fluids ↓IOP

Narrow angle glaucoma (Closed angle glaucoma)

- acute angle closure is defined as at least 2 of the following symptoms: ocular pain, nausea/vomiting, and a history of intermittent blurring of vision with halos; and at least 3 of the following signs: IOP greater than 21 mm Hg, conjunctival injection, corneal epithelial edema, mid-dilated nonreactive pupil, and shallower chamber in the presence of occlusion.

- Formation of adhesions between the iris and trabecular meshwork ↑IOP symptoms of pain, redness, and reduced vision

- Normal anterior chamber angle anatomy: the trabecular meshwork (TM) is found at the angle between the iris and the cornea, and constitutes the main drainage structure that removes aqueous humour (AH) from the eye. AH is produced by the ciliary body (CB), passing through the space between the iris and the lens into the anterior chamber, finally draining out of the eye from the TM.

- In pupil-block angle closure, AH is unable to pass through the anterior chamber due to the pupillary sphincter being adherent to the anterior lens. A positive force in the posterior chamber due to AH build-up leads to a rise in IOP, and blockage of the TM and anterior chamber angle