Setting: ED
CC: “I feel nauseated and I vomited twice.”
VS: BP: 104/68 mm Hg; P: 50 beats/minute; T: 98°F; R: 24 breaths/minute
HPI: An 84-year-old man comes to the ED with 1 to 2 days of increasing nausea and vomiting as well as diarrhea and some abdominal pain. The patient has been having visual disturbance and palpitations. His family says he has grown somewhat confused over the last several days.
PMHX:
Atrial fibrillation
Hypertension
Medications:
Chlorthalidone
Digoxin
Nifedipine
PE:
General: old man mumbling on a bed
Chest: clear to auscultation bilaterally
Cardiovascular: slow, irregularly irregular rate
Neurological: disoriented to time, examination incomplete secondary to lethargy
Initial Orders:
CHEM-7
ECG
Abdominal x-ray
Oximeter
Altered Mental Status
• Sodium level
• Glucose level
• Hypoxia
• Calcium level
• Liver or renal failure
• Intoxications
Potassium Disorders
• Cause arrhythmias
• Do not cause neurological problems
Move the clock forward to get the laboratory test results. Elderly patients can become disoriented with disorders that would be very minor for a younger person, such as cystitis or sleep disturbance. In an older person, just staying awake too much at night is enough to disorient them. You cannot diagnose “sundowning” like that until you have excluded the other “organic” problems listed in the box.
Report:
Oximeter: 97% saturation
What is the point of getting the abdominal film?
a. Perforation
b. Ileus or small bowel obstruction
c. Gallstones
d. Nephrolithiasis
Answer b. Ileus or small bowel obstruction
Abdominal x-ray or computed tomography (CT) is the only way to detect an ileus. Any electrolyte abnormality, such as abnormal levels of potassium, calcium, or magnesium, can paralyze the bowel. The intestines are a long muscular tube. These electrolytes make this muscle nonoperative.
Report:
CHEM-7: potassium 5.8 mEq/L (normal 3.5–5.2 mEq/L); BUN 38 g/dL (elevated); creatinine 2.0 mg/dL
ECG: atrial fibrillation, curved downsloping of ST segments, premature ventricular contractions; heart rate 50 beats/minute
Abdominal x-ray: multiple air fluid levels diffusely
What is the downsloping ST segment from?
a. Potassium
b. Digoxin
c. Dehydration
d. Renal insufficiency
Answer b. Digoxin
Digoxin can give downsloping of ST segments even at normal levels (Figure 11-4). This is not considered a sign of toxicity. Dehydration is present based on a BUN-to-creatinine ratio of 20:1. This is not surprising in an elderly person using a diuretic to control blood pressure (BP), although it is more common with a loop diuretic.
Figure 11-4. Electrocardiogram (ECG) demonstrating findings seen with therapeutic digoxin concentrations. A. ECG shows scooping of ST segments and small U waves with a serum digoxin level of 0.9 ng/mL. B. ECG shows scooping of ST segments, flattening of T waves, and first-degree atrioventricular block with a serum digoxin level of 1.2 ng/mL. (Reproduced with permission from Tintinalli JE, et al. Tintinalli’s Emergency Medicine, A Comprehensive Study Guide, 7th ed. New York: McGraw-Hill; 2011.)
Dehydration is a good reason for the patient’s disorientation. Potassium disorders do not cause cognitive dysfunction. Both dehydration and potassium elevation can cause an ileus. There is no specific therapy to reverse a small bowel obstruction. You have to correct the underlying cause, such as electrolyte problems, and wait for it to start moving again.
Orders:
IV normal saline
Stop digoxin and stop diuretics if not already done
Digoxin level
What is the most common toxicity associated with digoxin?
a. Cardiac
b. Neurological
c. Vision changes
d. GI tract
e. Electrolyte
Answer d. GI tract
Digoxin toxicity is rare because CHF is managed with angiotensin-converting enzyme (ACE) inhibitors, beta-blockers and spironolactone first. When it occurs, the most common symptoms are nausea, vomiting, and abdominal pain. These are nonspecific. The GI tract manifestations of digoxin toxicity have nothing unique to them. The most dangerous complication is cardiac arrhythmia. Virtually any rhythm disorder can occur. Yellow “halos” around objects are seen. This is part of neurological toxicity.
Altered mental status can be from digoxin toxicity.
Digoxin toxicity causes confusion
HypOkalemia (low potassium [K]) = Digoxin Toxicity
Digoxin toxicity leads to hypERkalemia.
Hyperkalemia Etiology
• Digoxin inhibits sodium- and potassium-activated adenosine triphosphatase (NaK ATPase)
What is the most common arrhythmia from digoxin toxicity?
a. Atrial fibrillation
b. Premature ventricular contractions
c. Ventricular tachycardia
d. Bradycardia
Answer b. Premature ventricular contractions
Any arrhythmia is possible with digoxin toxicity. Premature ventricular contractions (PVCs) are the most common. Supraventricular tachycardia (SVT) with variable block is extremely common. This patient’s bradycardia is definitely a manifestation of digoxin toxicity as is the abdominal distress, yellow halos around objects, and confusion.
Advance the clock and repeat the neurological examination.
PE:
Neurological: lethargic and confused
Vomiting causes hypokalemia.
Hypokalemia causes digoxin toxicity.
Digoxin and potassium compete for the same binding site on NaK ATPase.
Digoxin increases contractility by:
• Stimulating the ryanodine receptors
• Releasing calcium from the sarcoplasmic reticulum
Report:
Digoxin level: 3.2 ng/mL (elevated)
The patient has persistent neurological symptoms, an abnormal ECG, and hyperkalemia. All of these are indications for giving digoxin-binding antibodies.
Orders:
Digoxin-binding fragment antigen binding (Fab) antibodies
CHEM-7
Telemetry cardiac monitoring
Transfer to ICU if not already done
Digoxin-Binding Antibodies
• Fab portion of immunoglobulin G (IgG)
• Derived from sheep
• Excreted bound to digoxin renally
There should be an immediate effect of the digoxin-binding Fab portions. Bradycardia, confusion, and arrhythmias should quickly resolve.
Digoxin-Binding Fab
• It splits off the Fc portion.
• Papain splits into two pieces Fab and Fc.
Strongest Indications for Digoxin-Binding Fab
• Arrhythmia
• Symptomatic bradycardia
• Lethargy and confusion
• Hyperkalemia
As you move the clock forward, repeat the ECG, neurological examination, and potassium level. When these have normalized, move the patient out of the ICU. Because the indication for digoxin in this case is just rapid atrial fibrillation, switch digoxin to metoprolol or diltiazem or both. Both beta-blockers and diltiazem will control the heart rate and the BP.