by kathyhelms » Wed Jul 29, 2009 7:33 am
Propofol (2,6-diisopropylphenol) is an intravenous, nonbarbiturate anesthetic that is chemically unrelated to other intravenous anesthetics. Propofol is used to induce anesthesia that can be maintained by continuous infusion or with inhalation anesthetics. Propofol induces anesthesia as quickly as thiopental, but emergence from anesthesia is 10-times more rapid than with thiopental and is associated with minimal postoperative confusion. Only desflurane has a more rapid recovery time than propofol, but desflurane is associated with nausea/vomiting.[23940] Propofol has no analgesic activity and causes sedation at a lower dosage than that needed for anesthesia. Unlike many other general anesthetics, propofol possesses antiemetic activity. Propofol (Diprivan®) received FDA approval in October 1989. In March 1997, the FDA granted exclusivity until 2015 to Zeneca for a modified formulation that contains disodium edetate (EDTA) to retard microorganism growth. A generic formulation of propofol is available, but it contains sodium metabisulfite and not EDTA as the perservative.
IntravenousAdministration
•Only administer by intravenous (IV) administration by individuals trained in the administration of general anesthetics when used for general anesthesia or monitored anesthesia care sedation.
•Although not a controlled substance, propofol has been abused. Access restriction and accounting procedures are recommended.
•Strict aseptic technique must be followed during handling as the lipid-based vehicle is capable of supporting rapid growth of microorganisms. Disinfect the rubber stopper of the vial or prefilled syringe with 70% isopropyl alcohol.
Administration for ICU sedation directly from the vial must be completed within 12 hours of spiking the vial; discard tubing and any unused portion after 12 hours. If transferred to a syringe or other container before administration for ICU sedation, discard unused portions and IV lines at the end of the procedure or within 6 hours of opening the generic propofol vial or within 12 hours of opening the Diprivan® vial, whichever is sooner. For general anesthesia or procedural sedation, draw into sterile syringes immediately after opening the vials. After vial is spiked, complete administration within 6 hours for generic propofol and within 12 hours for Diprivan®. Discard unused portions, reservoir, dedicated administration tubing, and solutions containing propofol at the end of the procedure or within 6 hours of opening the generic propofol vial or within 12 hours of opening the Diprivan® vial, whichever is sooner. Flush the IV line every 6 hours for generic propofol and every 12 hours for Diprivan® and at the end of the anesthesia procedure.
•Possible cardiopulmonary adverse effects of propofol include respiratory depression, apnea, hypotension, and sinus bradycardia. Apnea is most common during anesthesia induction. Of 1573 adult patients that received induction with 2—2.5 mg/kg, 43% had apnea whereas 27% of 218 children had apnea after receipt of 1—3.6 mg/kg. The duration of apnea is usually between 30 and 60 seconds, although it was longer than 60 seconds in 12% of adult and 6% of pediatric patients. Hypotension is the most frequently occurring cardiopulmonary effect, reported in 3—10% of adult patients and in 17% of pediatric patients. The drop in arterial blood pressure can be more than 30% and is due to reduced preload and afterload. Patients may experience dizziness, although < 1% of patients reported this event during clinical trials. Administration of intravenous fluids or pressors and extremity elevation may be needed. There is usually little to no change in heart rate or cardiac output with the drop in blood pressure for patients that are breathing on their own. In contrast, a reduction in cardiac output and a greater extent of cardiac output depression are more likely for patients with assisted or controlled ventilation. Sinus bradycardia that occurs during a maintenance infusion may be due to a reduction in sympathetic activity or a resetting of the baroreceptor reflex. Propofol has no vagolytic activity. If the inhibitory effect on the heart is detrimental, administration of an anticholinergic drug to modify the increased vagal tone should be considered. Hypertension, sinus tachycardia, premature ventricular contractions (PVCs), premature atrial contractions (PACs), abnormal ECG, QT prolongation, ST-T wave changes, asystole, and cardiac arrest have occurred rarely (< 1% of patients). Fatal cardiac arrhythmias have been seen within 40—60 hours of therapy with propofol > 5 mg/kg/hour in patients with head trauma. Supraventricular tachycardia (SVT) with initially widening QRS seems to be a warning sign of these fatal arrhythmias. Cardiopulmonary adverse effects are largely dependent on the extent of premedication, propofol dosage and rate of administration, and underlying medical conditions. Cardiorespiratory depression is more likely with higher blood concentrations of propofol, which can result from the use of bolus doses or rapid increases in the infusion rate. Debilitated or elderly patients, and those with severe cardiac disease appear to experience more exaggerated responses. Patients with preexisting cardiac conduction abnormalities may have an arrhythmia exacerbation. The cardiovascular depressive effects have been attributed to direct vasodilation and negative inotropy. The respiratory depression may be due to direct suppression of the central inspiratory drive. If hypotension and respiratory depression are profound and refractory, overdose should be suspected.
To date, there has been no association of malignant hyperthermia with propofol. However, neuroexcitatory symptoms have been associated with propofol during and after drug administration. Neuroexcitatory symptoms may be a result of an imbalance between cortical and subcortical structures and decreased inhibitory output from the formatio reticularis. Perioperative myoclonia, rarely including seizures and a dystonic reaction known as opisthotonus has occurred with a temporal relationship to propofol administration. In clinical trials, hypertonia/dystonia occurred in < 1% of patients. Very rarely the use of propofol may be associated with the development of a period of postoperative unconsciousness that may be accompanied by an increase in muscle tone. A period of brief wakefulness may precede the event and recovery is spontaneous. There have been several cases reported in the literature. One patient became unresponsive and developed massaeter spasm 2 hours after propofol cessation. She awoke after 6 hours and reported being awake during the event. Symptoms occurred in most patients after regaining consciousness, within 7 hours of propofol cessation, and persisted for less than 24 hours, although symptom duration was longer in about a third of patients.[27362]
Propofol is isotonic and has a pH between 7.2 and 8.5. An injection site reaction, characterized by burning, stinging, and pain, has been reported in 17.6% of patients enrolled in clinical trials. However, immediate or delayed discomfort may occur in as many as 90% of adults and 85% of children. Phlebitis or thrombosis occurred in < 1% of patients in clinical trials. If extravasation occurs, local pain, swelling, blisters, and tissue necrosis may occur. Propofol is directly irritating to the venous intima. Propofol also activates the kallikrein-kinin system, which results in bradykinin production. Bradykinin dilates and increases the permeability of the vein. As a result, the aqueous-phase propofol irritates more free nerve endings outside the endothelial layer of the vessel. Less frequent reactions include tingling, numbness, and coldness. Options to decrease discomfort include use of the larger forearm veins, such as those of the antecubital fossa or the use of lidocaine 40 mg or granisetron 2 mg both in normal saline retained in a tourniquet-occluded vein for 2 minutes. The drugs similarly reduced the severity and incidence of pain associated with propofol injection. Lidocaine 1 ml of a 1% solution is commonly used. Other options that have been shown to reduce pain on injection are tramadol 50 mg and ondansetron 4 mg injected into a vein on the dorsum of the hand after a tourniquet has been applied to the forearm. The tourniquet is released after 20 seconds and propofol administered.
Anaphylactoid reactions that may include bronchospasm, erythema, hypotension, wheezing, laryngospasm, and angioedema have occurred shortly after administration of propofol. Anaphylactic shock is also possible. Because of concomitant use of other agents, a causal relationship has not been established. Likewise, pulmonary edema has been reported rarely with propofol, but a causal relationship is unknown, although a temporal relationship has been shown.
The FDA has received reports of several clusters of patients who have developed fever, chills, and body aches that began 6—18 hours after propofol receipt and persisted for up to three days. As of June 2007, all affected patients received propofol for sedation in gastrointestinal suites; in some cases, a vial was inappropriately used for more than one patient. No evidence of contaminated propofol vials and prefilled syringes exists, as determined by bacterial contamination testing of multiple units of propofol vials and lots that have been associated with the adverse events experienced by patients. Testing of other potential sources has also not identified any potentially causative agents. All patients recovered without apparent sequelae, but several patients have been hospitalized and one patient had seizures; no evidence of bacterial sepsis was noted. Sepsis should be considered in patients who develop hypotension, chills, fever, body aches, or other symptoms of an acute febrile reaction shortly after receiving propofol for sedation or general anesthesia; blood culture attainment and antimicrobial institution may be appropriate. Most studies with propofol have not examined infectious complications (other than contamination) as an outcome.[26919] Failure to use aseptic technique when handling propofol has been associated with microbial contamination of the product with fever, infection, other life-threatening illness, and/or death. Microbial contamination of propofol may occur even with use of aseptic technique. Propofol is not a microbially preserved product according to USP standards and thus, can support rapid growth of microbial organisms. Propofol is a single-use parenteral product; discard any unused portion within the specified time period (see Administration). Use of strict aseptic technique, adherence to the single-use requirement, and discarding of unused product within the specified time limits are paramount for safe use of propofol. Do not use if contamination is suspected. As determined from in vitro data, propofol may interfere with lymphocyte function, neutrophil function, and cytokine release. The clinical significance of these effects is unknown but may be greater when propofol is used for extended periods of time. Also, data have suggested that intravenous lipids (including propofol formulations) may alter the immune response to infection (e.g., interference with leukocyte migration and interleukin-2 dependent lymphocyte response). Healthcare providers are encouraged to report adverse events to the FDA's MedWatch Adverse Event Reporting program by calling 800—332—1088.
Propofol withdrawal syndrome has been described in a burn patient with concomitant bipolar disease receiving continuous IV infusions of propofol for 95 days to control extreme agitation and assist in ventilation. With each attempt to discontinue propofol, the patient required a restart of the propofol infusion to control abrupt agitation, tremors, tachycardia, tachypnea, and hyperpyrexia.[27575] Long-term infusions of propofol are controversial and no longer supported by the manufacturer, although long-term infusions have been administered without evidence of withdrawal. Although additional case reports of propofol withdrawal syndrome exist, the data are variable and inconclusive as to predict the risk factors for withdrawal. Withdrawal symptoms have been reported in patients with a duration of propofol infusion from days to several months.[27576] A propofol weaning protocol has been suggested (see Contraindications).