Usage
- Sulphur hexafluoride is an ultrasound contrast agent. It is used to improve the quality of an echocardiogram (ultrasound of the heart) or other ultrasound examinations by increasing the visibility of blood flow and internal structures. It enhances the echogenicity of the blood, leading to a clearer image. It is indicated for:
- Echocardiography to opacify the left ventricle and improve endocardial border delineation in adults and children with suboptimal echocardiograms.
- Ultrasonography of the liver to characterize focal liver lesions in adults and children.
- Ultrasonography of the urinary tract to evaluate vesicoureteral reflux in children.
- Pharmacological Classification: Ultrasound contrast agent.
- Mechanism of Action: Sulphur hexafluoride microspheres have a lower acoustic impedance than surrounding tissues. When exposed to ultrasound waves, these microspheres oscillate and resonate, creating strong echoes that enhance the ultrasound signal, making blood or other fluids appear brighter on the image.
Alternate Names
- International Nonproprietary Name (INN): Sulphur hexafluoride
- Brand Names: Lumason, SonoVue.
How It Works
- Pharmacodynamics: Sulphur hexafluoride microspheres enhance the contrast between blood (or urine in specific applications) and surrounding tissues during ultrasound examination. This effect is based on the physical properties of the microbubbles, not a chemical or biological interaction.
- Pharmacokinetics:
- Absorption: Not applicable (administered intravenously or intravesically). The gas itself, when released from the microbubbles, is absorbed into the bloodstream.
- Distribution: Primarily within the vascular compartment for intravenous use; within the urinary tract for intravesical use.
- Metabolism: The sulphur hexafluoride gas dissolves in the blood.
- Elimination: Rapidly eliminated through exhalation. The mean terminal half-life of sulfur hexafluoride is approximately 12 minutes (range 2-33 minutes) after intravenous administration. Over 80% is recovered in exhaled air within 2 minutes, and nearly 100% within 15 minutes.
- Mode of Action: Physical interaction with ultrasound waves; no receptor binding, enzyme inhibition, or neurotransmitter modulation is involved.
- Elimination Pathways: Exhalation (pulmonary).
Dosage
Standard Dosage
Adults:
- Echocardiography: 2 mL intravenous (IV) bolus, followed by a 5 mL saline flush. A second injection may be given during the same examination.
- Liver Ultrasonography: 2.4 mL IV bolus, followed by a 5 mL saline flush. A second injection may be given during the same examination.
Children:
- Echocardiography: 2 mL intravenous (IV) bolus, followed by a 5 mL saline flush. A second injection may be given during the same examination.
- Liver Ultrasonography: 0.03 mL/kg IV bolus (maximum 2.4 mL), followed by a 5 mL saline flush. A second injection may be given during the same examination.
- Urinary Tract Ultrasonography: 1 mL intravesical administration followed by instillation of saline until bladder is full. Second injection not needed for repeat imaging during the same examination.
- Pediatric Safety Considerations: Safety and efficacy are established for the labeled indications. Monitor for hypersensitivity reactions, as with adults.
Special Cases:
- Elderly Patients: No dose adjustment is needed.
- Patients with Renal Impairment: No dose adjustment required as excretion is primarily via the lungs.
- Patients with Hepatic Dysfunction: No dose adjustment required as excretion is primarily via the lungs.
- Patients with Comorbid Conditions: Use with caution in patients with unstable cardiopulmonary conditions. Close monitoring is recommended.
Clinical Use Cases
- Intubation: Not applicable.
- Surgical Procedures: Not applicable.
- Mechanical Ventilation: Not applicable.
- Intensive Care Unit (ICU) Use: May be used for echocardiography in critically ill patients. Monitor closely for adverse events.
- Emergency Situations: May be used for rapid assessment of cardiac function in specific emergency situations where echocardiography is indicated.
Dosage Adjustments:
- No specific dose modifications are typically required.
Side Effects
Common Side Effects
- Headache
- Nausea
- Altered taste
- Flushing (feeling of warmth)
- Injection site pain or warmth
Rare but Serious Side Effects
- Allergic reactions (including anaphylaxis)
- Cardiac arrhythmias
- Hypertension
- Hypotension
- Dyspnea (shortness of breath)
- Chest pain
Long-Term Effects
- No long-term adverse effects have been reported.
Adverse Drug Reactions (ADR)
- Anaphylaxis and other serious hypersensitivity reactions require immediate medical attention.
- Cardiopulmonary reactions, including arrhythmias, hypertension, and hypotension, require prompt intervention.
Contraindications
- Hypersensitivity to sulfur hexafluoride, any component of the formulation (e.g., polyethylene glycol), or any other ultrasound contrast agents.
- Right-to-left cardiac shunts (intravenous use).
- Severe pulmonary hypertension (pulmonary artery pressure > 90 mmHg) (intravenous use).
- Uncontrolled systemic hypertension (intravenous use).
- Adult respiratory distress syndrome (ARDS) (intravenous use).
Drug Interactions
- No clinically significant drug interactions have been identified. Dobutamine should be avoided with sulfur hexafluoride as it can exacerbate cardiopulmonary reactions.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: B (US FDA). Animal studies have not shown fetal harm. Adequate and well-controlled studies in pregnant women are lacking. Use only if clearly needed.
- Breastfeeding: Excretion in human milk is unknown. Caution is advised. Limited absorption by infants is expected, and breastfeeding continuation is generally considered acceptable. Discarding milk expressed for a short period (e.g., 24 hours) after administration may be considered, though not universally recommended.
Drug Profile Summary
- Mechanism of Action: Enhances ultrasound image contrast by creating microbubbles with different acoustic properties than blood.
- Side Effects: Headache, nausea, taste alteration, flushing, injection site reactions (common); hypersensitivity, arrhythmias, blood pressure changes, dyspnea, chest pain (rare but serious).
- Contraindications: Hypersensitivity; right-to-left shunts, severe pulmonary hypertension, uncontrolled hypertension, ARDS (IV use only).
- Drug Interactions: Limited; avoid dobutamine.
- Pregnancy & Breastfeeding: Category B; use with caution. Breastfeeding continuation is generally acceptable with possible short-term milk discarding.
- Dosage: Adults/Children: Echocardiography - 2ml IV, Liver - 2.4ml IV / 0.03ml/kg IV (max. 2.4ml), Urinary tract - 1ml intravesical.
- Monitoring Parameters: Vital signs (heart rate, blood pressure, respiratory rate, oxygen saturation), ECG in high-risk patients, observe for allergic reactions during and after administration.
Popular Combinations
- Not applicable. Sulfur hexafluoride is usually administered alone.
Precautions
- General Precautions: Screen for contraindications, including allergies and unstable cardiorespiratory status. Have resuscitation equipment and trained personnel readily available. Monitor for acute reactions, particularly in high-risk patients.
- Specific Populations: See Pregnancy and Breastfeeding section. Children are generally dosed by weight for liver ultrasonography and should be monitored closely for adverse reactions.
- Lifestyle Considerations: No specific lifestyle restrictions apply.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Sulphur Hexafluoride?
A: See the Dosage section above for detailed adult and pediatric recommendations based on the type of ultrasound examination.
Q2: What are the common side effects of Sulphur Hexafluoride?
A: Common side effects include headache, nausea, changes in taste, flushing, and injection site pain or warmth.
Q3: Is Sulphur Hexafluoride safe for use during pregnancy?
A: Pregnancy Category B. Animal studies have not shown fetal harm. Use only if clearly needed and discuss the risks and benefits with the patient.
Q4: Can Sulphur Hexafluoride be used in patients with kidney disease?
A: Yes, no dosage adjustment is needed for renal impairment because the drug is primarily eliminated through exhalation.
Q5: Are there any drug interactions with Sulphur Hexafluoride?
A: No significant drug interactions have been reported, however, concomitant use of dobutamine should be avoided.
Q6: How is Sulphur Hexafluoride administered?
A: It is administered as an intravenous bolus injection for echocardiography and liver ultrasonography, and intravesically for urinary tract ultrasonography. Always follow with a saline flush for intravenous administration.
Q7: What are the contraindications for using Sulphur Hexafluoride?
A: Contraindications include hypersensitivity to the drug or its components, right-to-left cardiac shunts, severe pulmonary hypertension, uncontrolled systemic hypertension, and acute respiratory distress syndrome (for intravenous use).
Q8: What should be done in case of a serious reaction to Sulphur Hexafluoride?
A: Immediately discontinue administration and provide supportive care as needed. Have resuscitation equipment and trained personnel readily available. Serious reactions may require treatment with epinephrine, corticosteroids, or other interventions depending on the specific symptoms.
Q9: How long does the contrast enhancement effect of Sulphur Hexafluoride last?
A: The contrast enhancement typically lasts for a few minutes, allowing enough time for the necessary imaging. A second injection may be administered during the same examination if needed to prolong the effect.
