Isoflurane Fahrenheit Special Precautions

lsoflurane markedly increases cerebral blood flow at deeper levels of anesthesia. There may be a transient rise in cerebral spinal fluid pressure which is fully reversible with hyperventilation.
Since levels of anesthesia may be altered easily and rapidly, only vaporizers producing predictable concentrations and flow rates should be used. Hypotension and respiratory depression increase as anesthesia is deepened.
Reports of QT prolongation, associated with torsade de pointes (in exceptional cases, fatal), have been received. Caution should be exercised when administering isoflurane to patients at risk for QT prolongation.
Caution should be exercised in administering general anesthesia, including isoflurane, to patients with mitochondrial disorders.
Blood losses comparable with those found following anesthesia with other inhalation agents have been recorded with lsoflurane in patients undergoing induced abortion. Adequate data have not been developed to established the use of lsoflurane in obstetric anesthesia.
Isolated cases of increased carboxyhemoglobin have been reported with the use of fluorinated inhalation agents (i.e., desflurane, enflurane and isoflurane). No clinically significant concentrations of carbon monoxide are produced in the presence of normally hydrated absorbents. Care should be taken to follow manufacturers' instructions for CO₂ absorbents.
Rare cases of extreme heat, smoke and/or spontaneous fire in the anesthesia machine have been reported during administration of general anesthesia with drugs in this class when used in conjunction with desiccated CO₂ absorbents, specifically those containing potassium hydroxide (e.g. Baralyme). When a clinician suspects that the CO₂ absorbent may be desiccated, it should be replaced before administration of lsoflurane. 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.
General: As with any potent general anesthetic, isoflurane should only be administered in an adequately equipped anesthetizing environment by those who are familiar with the pharmacology of the drug and qualified by training and experience to manage the anesthetized patient.
Since levels of anesthesia may be altered quickly and easily with isoflurane, only vaporizers which deliver a predictable output with reasonable accuracy, or techniques during which inspired or expired concentrations can be monitored, should be used. The degree of hypotension and respiratory depression may provide some indication of anesthetic depth.
As with other halogenated agents, isoflurane must be used with caution in patients with increased intracranial pressure. In such cases hyperventilation may be necessary.
The action of non-depolarizing relaxants is markedly potentiated with isoflurane.
lsoflurane should be administered with caution to patients who can develop bronchoconstriction since bronchospasm can occur.
lsoflurane may cause respiratory depression, which may be augmented by narcotic premedication or other agents causing respiratory depression. Respiration should be supervised and if necessary, assisted.
lsoflurane, as well as other general anesthetics, may cause a slight decrease in intellectual function for 2 - 4 days following anesthesia. As with other anesthetics, small changes in moods and symptoms may persist for up to 6 days after administration (see EFFECTS ON ABILITY TO DRIVE AND USE MACHINES as follows).
Malignant Hyperthermia: In susceptible individuals, isoflurane anesthesia may trigger a skeletal muscle hypermetabolic state leading to high oxygen demand and the clinical syndrome known as malignant hyperthermia. The syndrome includes nonspecific features such as muscle rigidity, tachycardia, tachypnea, cyanosis, arrhythmias, and unstable blood pressures. (It should also be noted that many of these nonspecific signs may appear with light anesthesia, acute hypoxia, etc.) PaO₂ and pH may decrease, and hyperkalemia and a base deficit may appear.
There have been postmarketing reports of malignant hyperthermia. Some of these reports have been fatal.
Treatment includes discontinuance of triggering agents (e.g. isoflurane), intravenous administration of dantrolene sodium, and application of supportive therapy. Such therapy includes vigorous efforts to restore body temperature to normal, respiratory and circulatory support as indicated, and management of electrolyte-fluid-acid-base derangements (Consult prescribing information for dantrolene sodium intravenous for additional information on patient management). Renal failure may appear later, and urine flow should be sustained if possible.
Perioperative Hyperkalemia: Use of inhaled anesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in pediatric patients during the postoperative period. Patients with latent as well as overt neuromuscular disease, particularly Duchenne muscular dystrophy, appear to be most vulnerable. Concomitant use of succinylcholine has been associated with most, but not all, of these cases. These patients also experienced significant elevations in serum creatine kinase levels and, in some cases, changes in urine consistent with myoglobinuria. Despite the similarity in presentation to malignant hyperthermia, none of these patients exhibited signs or symptoms of muscle rigidity or hypermetabolic state. Early and aggressive intervention to treat the hyperkalemia and resistant arrhythmias is recommended, as is subsequent evaluation for latent neuromuscular disease.
Effects on Ability to Drive and Use Machines: Patients should be advised that performance of activities requiring mental alertness, such as operating a motor vehicle or hazardous machinery, may be impaired for 2 - 4 days after anesthesia with isoflurane. As with other anesthetics, small changes in moods and symptoms may persist for up to 6 days after administration.