sulfur hexafluoride: clinical use

Prescribing considerations

• Restrict use to diagnostic ultrasound when an unenhanced study is inconclusive and ensure experienced personnel and resuscitation facilities are available.
• Observe every patient closely during and for at least 30 minutes after administration.
• Undertake careful benefit–risk assessment in recent acute coronary syndrome, unstable ischaemic disease, acute or advanced heart failure, severe arrhythmia or recent coronary intervention.
• Use caution where clinical exposure is limited, including acute endocarditis, prosthetic valves, sepsis, hypercoagulable states, recent thromboembolism and end-stage renal or hepatic disease.
• A negative contrast-enhanced voiding urosonogram does not completely exclude vesicoureteral reflux.

Contraindications and cautions

• Hypersensitivity to sulfur hexafluoride or any excipient; previous polyethylene-glycol hypersensitivity may increase the risk of a serious reaction.
• For intravenous use: known right-to-left shunt, severe pulmonary hypertension, uncontrolled systemic hypertension or adult respiratory distress syndrome.
• Combination with dobutamine where cardiovascular instability makes dobutamine contraindicated.

Monitoring

• Maintain close clinical observation for hypersensitivity during and after administration.
• Use ECG monitoring in high-risk patients when clinically indicated.
• Monitor ECG and blood pressure during pharmacological stress echocardiography.
• Use an appropriately low ultrasound mechanical index.

Clinical pharmacology

Inert sulfur hexafluoride microbubbles reflect ultrasound at the gas–liquid interface, enhancing blood echogenicity or urinary-fluid signals. After intravenous administration, the gas dissolves in blood and is rapidly exhaled rather than being cleared through the kidneys.

Formulation and product differences

• The selected product is a powder and sodium-chloride solvent that must be reconstituted into a homogeneous, milky microbubble dispersion before administration.
• The same prepared dispersion has distinct licensed routes: intravenous diagnostic imaging in adults and intravesical urinary-tract imaging in children.
• The vial is single-use, contains polyethylene glycol among its excipients and should be used promptly after preparation.