Sevoflurane Fahrenheit

Sevoflurane.

Each bottle contains: Sevoflurane 250 mL.

Action Mechanism: The depth of anesthesia changes rapidly following changes in the inspired concentration of Sevoflurane. Emergence and recovery are particularly rapid. Therefore, patients may require early post-operative pain relief. As with all other inhalation agents, Sevoflurane depresses cardiovascular function in a dose related fashion. Increases in Sevoflurane concentration resulted in decrease in mean arterial pressure, but there was no change in heart rate. Sevoflurane did not alter plasma or adrenaline concentrations. No evidence of seizures was observed. In patients with normal intracranial pressure (ICP), Sevoflurane had minimal effect on ICP and preserved CO₂ responsiveness.
The safety of Sevoflurane has not been investigated in patients with a raised ICP in patients at risk for elevations of ICP, Sevoflurane should be administered cautiously conjunction with ICP reducing maneuvers such as hyperventilation.

For induction and maintenance of general anesthesia for in-patient and out-patient surgery in both adults and children.

Vaporisers specifically calibrated for use with Sevoflurane should be used so that the concentration delivered can be accurately controlled. MAC (minimum alveolar concentration) values for Sevoflurane decrease with age and with the addition of nitrous oxide. The table as follows indicates average MAC values for different age groups. See table.


Click on icon to see table/diagram/image


Premedication: Premedication should be selected according to the need of the individual patient, and at the discretion of the anaesthetist. The use of anticholinergic drugs is a matter of choice.
Induction: Anesthesia can be induced in adults and children with Sevoflurane. Dosage should be individualized and titrated to the desired effect according to the patient's age and clinical status. A short acting barbiturate or other intravenous induction agent may be administered followed by inhalation of Sevoflurane. Induction with Sevoflurane may be achieved in oxygen or in combination with oxygen-nitrous oxide mixtures. In adults inspired concentrations of up to 5% Sevoflurane usually produce surgical anesthesia in less than 2 minutes.
In children, inspired concentrations of up to 7% Sevoflurane usually produce surgical anesthesia in less than 2 minutes.
Maintenance: Surgical levels of anesthesia may be sustained with concentration of 0.5-3% Sevoflurane with or without the concomitant use of nitrous oxide.
Elderly: As with other inhalation agents, lesser concentrations of Sevoflurane are normally required to maintain surgical anesthesia. See as previously mentioned for MAC values.
Emergence: Emergence times are generally short following Sevoflurane anaesthesia. Therefore, patients may require early post-operative pain relief.

In the event of overdosage, the following action should be taken: Stop drug administration, establish a clear airway and initiate assisted or controlled ventilation with pure oxygen and maintain adequate cardiovascular function.

Sevoflurane should be used in patients with known sensitivity to Sevoflurane. Sevoflurane is also contraindicated in patients with known or suspected genetic susceptibility to malignant hyperthermia.

Sevoflurane should be administered only by person trained in the administration of general anaesthesia. Facilities for maintenance of a patient airway, artificial ventilation, oxygen enrichment and circulatory resuscitation must be immediately available. Sevoflurane should be delivered via a vaporizer specifically calibrated for use with Sevoflurane so that the concentration delivered can be accurately controlled. Hypotension and respiratory depression increase as anaesthesia is deepened.
During the maintenance of anaesthesia, increasing the concentration of Sevoflurane produces dose-dependent decreases in blood pressure. Excessive decrease in blood pressure may be related to depth of Sevoflurane. The recovery from general anaesthesia should be assessed carefully before patients are discharged from the recovery room.
In susceptible individuals, potent inhalation anesthetic agents may trigger a skeletal muscle hypermetabolic state leading to high oxygen demand and the clinical syndrome known as malignant hyperthermia. The syndrome may include non-specific feature such as muscle rigidity, tachycardia, tachypnoea, cyanosis, arrhythmias and unstable blood pressure. Treatment includes discontinuation of triggering agents (e.g. Sevoflurance), administration of intravenous dantrolene sodium, and application of supportive therapy. Renal failure may appear later, and urine flow should be monitored and sustained if possible. Sevoflurane should be used with caution in patients with renal insufficiency (baseline serum creatinine greater than 133 micromol/litre).
Sevoflurane produces low levels of Compound A (pentafluoroisopropenyl fluoromethyl ether (PIFE)) and trace amounts of Compound B (pentafluoromethoxy isopropyl fluoromethyl ether (PMFE)), when in direct contact with CO₂ absorbents. Levels of Compound A increase with: increase in canister temperature; increase in anaesthesia concentration; decrease in gas flow rate and increase more with the use of Baralyme rather than Soda lime.
Nephrotoxicity was seen exposed to levels of Compound A in excess of those usually seen in routine clinical practice. The mechanism of this renal toxicity is unknown.
Experience with repeat exposure to Sevoflurane is very limited. However, there were no obvious differences in adverse events between first and subsequent exposures.
Replacement of Desiccated CO₂ Absorbents: The exothermic reaction that occurs with Sevoflurane and CO₂ absorbents is increase when the CO₂ absorbent becomes desiccated, such as after an extended period of dry gas flow through the CO₂ absorbent canisters. Rare cases of extreme heat, smoke and/or spontaneous fire in the anaesthesia machine have been reported during Sevoflurane use in conjunction with the use of desiccated CO₂ absorbent. An unusually delayed rise or unexpected decline of inspired Sevoflurane concentration compared to the vaporizer setting may be associated with excessive heating of the CO₂ absorbent canister.
When clinician suspects that CO₂ absorbent may be desiccated, it should be replaced before administration of Sevoflurane. The color indicator of most CO₂ absorbents does not necessarily change as a result of desiccation. Therefore, the lack of significant color change should not be taken as an assurance of adequate hydration. CO₂ absorbents should be replaced routinely regardless of the state of the color indicator.
Pharmaceutical Precautions: Sevoflurane is chemically stable. As with some halogenated anaesthetics, minor degradation occurs through direct contact with CO₂ absorbents. The extent of degradation in clinically insignificant and no dose adjustments or change in clinical practice is necessary when rebreathing circuits are used. Higher levels of Compound A are obtained when using Baralyme rather than Sode lime.
Further Information: The low solubility of Sevoflurane in blood should result in alveolar concentrations which rapidly increase upon induction and rapidly decrease upon cessation of the inhaled agents.
ln humans <5% of the absorbed Sevoflurane is metabolized. The rapid and extensive pulmonary elimination of Sevoflurane minimizes the amount of anaesthetic available for metabolism. Sevoflurane is defluorinated via cytochrome P450(CYP)2E1 resulting in the production of hexafluoroisopropanol (HFIP) with release of inorganic fluoride and carbon dioxide (or a one carbon fragment). HFIP is then rapidly conjugated with glucuronic acid and excreted in the urine. The metabolism of Sevoflurane may be increased by known inducers of CYP2E1 (e.g. isoniazid and alcohol), but it is not inducible by barbiturates.
Transient increases in serum inorganic fluoride levels may occurs during and after Sevoflurane anaesthesia.
Generally, concentrations of inorganic fluoride peak within 2 hours of the end of Sevoflurane anaesthesia and return within 48 hours to preoperative levels.
Effects on Driving Ability and Operation of Machinery: As with other anaesthetic agents, patients should be advised that performance of activities requiring mental alertness, such as operating hazardous machinery, may be impaired for some time after general anaesthesia. Patients should not be allowed to drive for a suitable period after Sevoflurane anaesthesia.

Sevoflurane should be used during pregnancy only if clearly needed.
It is not known whether Sevoflurane is excreted in human milk therefore caution should be exercised when Sevoflurane is administered to a nursing women.

As with all potent inhaled anaesthetics, Sevoflurane may cause dose-dependent cardiorespiratory depression. Most adverse events are mild to moderate in severity and transient.
Nausea and vomiting are commonly observed in the post-operative period, at a similar incidence to those found with other inhalation anaesthetics. These effects are common sequelae or surgery and general anaesthesia which may be due to inhalational anaesthetic, other agents administered intraoperatively or post-operatively and to the patient's response to the surgical procedure.
The type, severity and frequency of adverse events in Sevoflurane patients were comparable to adverse events in patients treated with other inhalation anaesthetics.
The most frequent adverse events associated with Sevoflurane overall were nausea and vomiting. Agitation occurred frequently in children. Other frequent adverse events associated with Sevoflurane administration overall were: increased cough and hypotension.
In addition to nausea and vomiting, other frequent adverse events by age listings were: In adults, hypotension; in elderly, hypotension and bradycardia; In children, agitation and increased cough.
Less frequent adverse events associated with Sevoflurane administration were: agitation, somnolence, chills, bradycardia, dizziness, increased salivation, respiratory disorder, hypertension, tachycardia, laryngismus, fever, headache, hypothermia, increased SGOT.
Occasional adverse events occurring during clinical trials included: arrhythmias, increased LDH, increased SGPT, hypoxia, apnoea, leukocytosis, ventricular extrasystoles, supraventricular extrasystoles, asthma, confusion, increased creatinine, urinary retention, glycosuria, atrial fibrillation, complete AV block, bigeminy, leucopenia. Malignant hyperthermia and acute kidney failure have been reported very rarely. Rare reports of post-operative hepatitis exist, but with an uncertain relationship to Sevoflurane. Convulsions may occur extremely rarely following Sevoflurane administration, particularly in children.
There have been very rare reports of pulmonary oedema.
Allergic reaction, such as rash, urticaria, pruritus, bronchospasm, anaphylactic or anaphylactoid reactions have been reported.
As with other anaesthetic agents, cases of twitching and jerking movements with spontaneous resolution have been reported in children receiving Sevoflurane for induction of anaesthesia with an uncertain relationship to Sevoflurane.
Laboratory Findings: Transient elevations in glucose and white blood cell count may occur as with use of other anaesthetic agents. Occasional cases of transient changes in hepatic function tests were reported with Sevoflurane.

The action of non-depolarising muscle relaxants is markedly potentiated with Sevoflurane, therefore, when administered with Sevoflurane, dosage adjustments of these agents should be made.
Sevoflurane is similar to Isoflurane in the sensitization of the myocardium to the arrythmogenic effect of exogenously administered adrenaline.
MAC values for Sevoflurane decrease with the addition of nitrous oxide as indicated in the table on "Effect of Age on MAC of Sevoflurane" (see DOSAGE & ADMINISTRATION). As with other agents, lesser concentrations of Sevoflurane may be required following use of an intravenous anaesthetic e.g. propofol. The metabolism of Sevoflurane may be increased by known inducers of CYP2E1 (e.g. isoniazid and alcohol), but it is not inducible by barbiturates.

Some halogenated anaesthetics have been reported to interact with dry carbon dioxide absorbent to form carbon monoxide. To date there is no evidence that this can occur with Sevoflurane. However, in order to minimize the risk of formation of carbon monoxide in re-breathing circuits and the possibility of elevated carboxy-haemoglobin levels, carbon dioxide absorbent should not be allowed to dry out.

Store below 30°C.

Anaesthetics - Local & General

N01AB08 - sevoflurane ; Belongs to the class of halogenated hydrocarbons. Used as general anesthetics.

G