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Cardiac Arrest and Pulmonary Edema can be either Physiologic or Allergic-Like
As technologists, our first job is to call for help. We may also retreive the "crash cart" and start Oxygen administration- 6-10 L/min. In emergencies, the MD will instruct which drugs to give; usually Epinephrine or Antihistamines.
Vasovagal reactions typically self-rectify, so the patient's BP and HR should be monitored for LOC, seizures, angina, or cardiac arrest.
Glucophage, a diabetes medication can react with ROCM by causing lactic acidosis. This is a delayed reaction, with symptoms of N/V, muscle weakness, dyspnea, abdominal pain, and cardiac rhythm abnormalities, but can be prevented by stopping the medication for 48 hours before the exam, keeping the patient hydrated, and checking to ensure the patient's serum creatinine levels are normal.
Nephropathy is a concern for patients who are elderly, diabetic, anemic, or have preexisting renal impairment. It Prevent nephropathy by stopping nephrotoxic drugs before the exam, keeping the patient hydrated with a 0.9% NaCl IV, vasodilators, antioxidants, corticosteroids, or diphenhydramine.
Nephrogenic Systemic Fibrosis (NSF) is the thickening and scarring of connective tissue (which can involve lungs, esophagus, heart, skeletal muscles), and causes contractures or joint immobility. It is caused by exposure to Gadolinium, but mostly with patients who have end-stage renal disease or acute kidney injuries. Prevent NSF by getting a thorough history of kidney issues.
Extravasation is the escape of CM into surrounding tissues, and is more painful and common with HOCM. It can result in skin ulceration, soft-tissue necrosis, nerve or muscle damage. Prevent extravasation by using correct injection techniques, not injecting large volumes of ROCM, using larger veins and new IV's, and asking the patient to report burning or swelling sensations. Treat extravasation by stopping the injection, calling the nurse or physician, removing the IV, elevating the affected area above the heart, and applying a warm or cold compress.

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Reaction Symptoms: Allergic & Physiologic

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Reaction Symptoms: Allergic & Physiologic

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_________Mild_________
Allergic-Like:

Limited urticaria, pruritis

Limited cutaneous edema

Limited itchy/scratchy throat

Nasal congestion

Sneezing

Conjunctivitis

Rhinorrhea

Physiologic:

Limited N/V

Transient flushing, warmth, chills

H/A

Dizziness

Anxiety

Altered taste/metallic taste

Mild hypertension

Vasovagal that resolves quickly

________Moderate_______
Allergic-Like:

Diffuse urticaria & pruritis

Diffuse erythema

Stable vital signs

Facial edema, no dyspnea

Throat tightness/hoarse, no dyspnea

Wheezing/bronchospasm

Mild or no hypoxia

Physiologic:

Protracted N/V

Hypertensive urgency

Isolated chest pain

Vasovagal reaction requiring treatment; responds to treatment

_________Severe___________
Allergic-Like:

Diffuse edema

Facial edema w/dyspnea

Diffuse erythema w/ hypotension

Laryngeal edema w/stridor And/or hypoxia

Wheezing, bronchospasm, hypoxia

Anaphylactic shock: Hypotension & tachycardia

Physiologic:

Vasovagal rxn resistant to treatment

Arrythmia

Convulsions, seizures

Hypertensive emergency

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Up to 54% of patients have SOME reaction. However;

Adverse effects in 2-17%

HOCM: 5-15% experience acute adverse effects

LOCM: Overall allergic-like + physiologic < 1%

0.04% serious reactions

0.9 per 100,000  (0.0009%) fatality

2.1 fatality per 1 million (0.00021%)

Gadolineum: 0.01-0.22% aggregate

0.008% severe

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Happen <60 min post-injection, generally pseudoallergic (no release of IgE antibodies), most need minimal intervention.

Mild: self-limiting, do not get worse
Moderate: more pronounced, requires some medical attention
Severe: life-threatening or permanent morbidity w/o medical intervention

Allergic Risks:
Previous Reaction to CM: increase risk by 5x (for that CM class)
Unrelated Allergies: increase risk by 2-3x
Asthma Hx: more prone to bronchospasm
COPD Hx: more prone to pulmonary edema

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requires prior exposure to foreign substance... no reaction on first exposure, mast cells sensitized. On the Second Exposure, strong, life-threatening reaction from immune system. IgE triggers mast cells to release histamine. Life-threatening.

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Rare
-headache
-nausea
-dysgeusia (metallic or off taste)

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Lower incidence than Iodine, but similar reactions
Large, complex molecule
Usually self-correcting, increase in iron/bilirubin concentrations up to 4 hours post-injection
◦Also not related to previous reactions to Iodine
◦Anaphylaxis occurs in only 0.13-0.22% of patients
◦Can cause Nephrogenic System Fibrosis

Cardiovascular:

◦Vasovagal, hypo- or hypertension, syncope, tachycardia, pallor, CP, cardiac arrest

CNS:

◦Headache (common), Dizziness, paresthesia, drowsiness, weakness, arrest

GI:

◦N/V, gastric pain, dysgeusia, excess or no salivation

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Chelation
ROCM can bind to the Calcium ions in blood, leading to abnormal heart rhythms, cardiac arrest, or pulseless electrical activity
Drugs can also interact and produce precipitates- avoid by using a new IV for contrast

Anticoagulation:
HOCM can cause blood to thin, leading to bruising or bleeding. This isn't seen with LOCM.

Chemotoxic effects can be reduced by injecting slower or into different vessels.
Osmotic Effects: At the time of injection, RBC's shrink or sickle, and the blood vessel lining also shrinks. Vasodilation and flushing occurs, sometimes leading to a hot flash feeling.  These are self-limiting side effects and NOT an allergic-like reaction. As the bolus of contrast circulates, fluid will shift back into RBC's and extravascular tissue.

Chronic Diseases:
Sickle cell anemia

◦RBCs will sickle due to osmotic activity

Multiple myeloma

◦Acute renal failure

Pheochromocytoma (rare, benign adrenal gland tumor)

◦Hypertensive crisis

Subarachnoid hemorrhage

◦Intractable seizures

Pregnancy
◦will cross placental barrier

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Allergic-like:
-immune system stimulating
-4 names; Idiosyncratic, anaphylactoid, allergic-like, systemic
-can be premedicated for using corticosteroids (prednisone) or antihistimines (diphenhydramine)
-NOT related to dose or Iodine concentration

Physiologic:
-4 Types; Chemotoxic (from I concentration), Osmolality, Calcium Chelation, Anticoagulation
-Related to I concentration, dose, injection rate, technique

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Physiologic Effects per System (Iodinated CM)

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Physiologic Effects per System (Iodinated CM)

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Dose related, Iodine concentration (280-370mg/ml) dependent
Effects are likely caused by osmolality, viscosity, salt content, Ca binding properties, and hydrophilicity of ROCM (chemotoxic)
Generalized Adverse Rxns: N/V, flushed/warm feeling, rhinitis, lacrimation, sneezing, itching, rash, edema, cramps, salivaition, diphoresis, chills, fever, decreased WBC, intravascular coagulation

Injection Site:
-thrombophlebitis, pain, burning/stinging, numbness, bruising, necrosis

Thyroid (Storm): rare
-related to I concentration (higher=more likely)
-Fever, tachycardia, diaphoresis, agitation, nervousness
-If untreated, CHF, pulmonry, cardiovascular collapse, death

Renal
-decrease in Renal function within 48 hours of injection
-osmotic shifts cause; increase in renal fluid volume, decrease in renal bloodflow = decrease O2 = damage to renal medulla in form of ischemia
-urine becomes hyperosmolar, leading to dehydration
At-Risk Populations: preexisting renal compromise, diabetic w/ renal dysfunction or dehydration
Staying hydrated is the key to prevention

Cardiovascular
-Osmotic shifts can trigger heart failure- the heart cannot handle fluid load, chain of events with hormone release can lead to death

-Presents as; Respiratory difficulty, pulmonary edema, brady/tachycardia, hyper/hypotension, cardiac dysrhythmia or arrest
At-Risk populations: underlying cardiac disease, such as CHF,

Vagovasal: common
-likely due to anxiety, since it can occur at any time during the exam
-Caused by stimulation of baroreceptors & chemoreceptors in aortic arch
-Vagus nerve stimulated by vascular hypertension from stress
-Leads to hypotension and bradycardia, then LOC

CNS
-Nervousness, confusion, anxiety, headache, dizziness, tremors, agitation, seizures

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NO gas embolus
Safe:
- injection into synovial joints

Not Safe:
- pneumothorax
- small bowel obstruction
- intraocular gas bubble

Properties:
- no gas embolus
- vapors heavier than air

Exams:
- not commonly used in radiology

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Rapidly absorbed by body, can cause gas embolus
Safe:
- GI tract

Not Safe:
-injection into synovial joints or bloodstream

Properties:
- rapidly absorbed by body
- low solubility (can make air bubbles)
- not commonly used in radiology

Exams
- not commonly used in radiology

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Diatrizoate meglumine or sodium
Used when barium contraindicated
High Osmolality

Adverse Effects

Diarrhea

Hypovolemia (systemic)

Dehydration

Electrolyte imbalance

Aspiration- Causes copious osmotic effusion

Pulmonary edema, pneumonitis,
death

Anaphylaxis (theoretically)

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Adverse Effects
Fluid overload due to absorption of water from enema into vascular system

pulmonary edema, seizure, coma, death

Colon or Vaginal perforation from enema tip
Allergic reaction

latex enema tip or preservatives

Aspiration

blocks alveoli and stops air exchange

Leakage into bloodstream via gastric mucosa

barium embolus

Constipation

Contraindications

suspected GI tract perforation (barium peritonitis)

diverticulitis

ulcerative collitis

toxic megacolon

chronic constipation

pre-CT (too dense for CT)

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Dimer - Large Molecule

Low Osmolality

3:1 compound ratio (3 iodine : 1 osmotic particle)

More Water Soluble

Hydrophilic

Viscosity

can be warmed to decrease

more viscous than Ionic contrast

Miscibility: completely miscible with blood to avoid contrast embolization.
Persistence: remains in body just long enough to image

Adverse Effects

Effects less common than ionic CM - doesn't dissociate into cation and anion

Warm, flushed feeling, N/V

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Dimer - Larger molecule - 2 rings

Slightly Lower osmolality

3:1 compound ratio (6 iodine : 2 osmolar molecules)

Higher Viscosity than monomer

Adverse Effects

Not as likely to occur as HOCM, but more likely than LOCM

Same effects as HOCM

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Usually Monomer - Smaller molecule - 1 ring

High osmolality

Hypertonic and chemotoxic side effects

3:2 compound ratio (3 iodine : 2 osmolar molecules)

Lower Viscosity than dimer

Meglumine in position 1: more viscous (bigger)

Sodium in position 1: less viscous

Adverse Effects

Effects 1 in 50 patients (common due to high osmolality)

Warm, flushed feeling, N/V on injection, painful injection, extravasation injuries

Sodium more toxic than Meglumine

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1 Barium
1 Sulfur
4 Oxygen atoms

Indicated for Enteral Studies or GI disease

Solubility

not soluble in water, instead forms a suspension

isn't absorbed through any membranes/no interaction

Viscosity

powder- very viscous, depends on how much water you mix with

Persistence

Depends on study, usually takes 1-3 days for the barium to leave system after swallowing

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Benzene Ring
Acid in position 1

Adding Methylglucamine or Sodium can increase osmolality (more water moves into the blood)

Iodine Atoms in positions 2, 4, 6
Side groups in positions 3, 5

Determine solubility, lipophilicity, and toxicity

Solubility: In blood, it splits into:

1. Anion—benzene ring with Iodine

2. Cation—sodium atoms or meglumine molecules

Miscibility: completely miscible with blood to avoid contrast embolization.
Persistence: remains in body just long enough to image, not long enough to harm
Osmolality:

Enteral: high osmolality

Gastrografin: high osmolality, often diluted with water

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Can cause gas embolus
Safe:
- injection into synovial joints
- ingestion (small amounts)

Not Safe:
- injection into bloodstream

Properties
-takes up space, exerts pressure, can expand

Exams
-Double contrast UGI, esophagram, barium enema, soft tissue neck, double contrast arthrogram

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Rapidly absorbed by the body, does not cause gas embolus
Safe:
- injection into synovial joints

Not Safe:
- pulmonary artery vapor lock in venous system

Properties:
- low viscosity
- rapidly absorbed by body
- more soluble

Exams:
- UGI/double contrast UGI, esophagram, barium enema