Anesthesia maintenance

Intra-operative analgesia during anesthesia maintenance... 

Propofol (Diprivan) is used for induction and maintenance of anesthesia. It also may be used for sedation during diagnostic procedures and procedures that use a local anestiietic. This drug also is used for continuous sedation of intubated or respiratory-controlled patients in intensive care units. 

Sevoflurane (Ultane) is an inhalational analgesic. It is used for induction and maintenance of general anesthesia in adult and pediatric patients for inpatient and outpatient surgical procedures. 

An anesthetic gas, cyclopropane has a rapid onset of action and may be used for induction and maintenance of anesthesia Skeletal muscle relaxation is produced with full anesthetic doses. Cyclopropane is supplied in orange cylinders. Disadvantages of cyclopropane are difficulty in detecting the planes of anesthesia, occasional laryngospasm, cardiac arrhythmias, and postanesthesia nausea, vomiting, and headache Cyclopropane and oxygen mixtures are explosive, which limits the use of this gas anesthetic. 

Halothane (Fluothane) is a volatile liquid given by inhalation for induction and maintenance of anesthesia Induction and recovery from anesthesia are rapid, and the depth of anesthesia can be rapidly altered. Halothane does not irritate the respiratory tract, and an increase in tracheobronchial secretions usually does not occur. Halothane produces moderate muscle relaxation, but skeletal muscle relaxants may be used in certain types of surgeries. This anesthetic may be given with a mixture of nitrous oxide and oxygen. 

Desflurane (Suprane), a volatile liquid, is used for induction and maintenance of anesthesia A special vaporizer is used to deliver this anesthetic because delivery by mask results in irritation of the respiratory tract. 

Endotracheal Intubation Passage of a tube through the nose or the mouth into the trachea for maintenance of the airway during anesthesia or for maintenance of an imperiled airway. 

Concentrations of ethyl ether ranging from 100,000 to 150,000 are required for induction of human anesthesia however, exposure at this concentration may also produce fatalities from respiratory arrest. Maintenance of surgical anesthesia is achieved at... 

ALFENTANIL HYDROCHLORIDE As an analgesic adjunct given in incremental doses in the maintenance of anesthesia with barbiturate/nitrous oxide/oxygen. 

As an analgesic administered by continuous infusion with nitrous oxide/oxygen in the maintenance of general anesthesia. 

Pain - For analgesic action of short duration during anesthesia (premediaction, induction, maintenance) and in the immediate postoperative period (recovery room) as needed. 

For use as a narcotic analgesic supplement in general or regional anesthesia. For administration with a neuroleptic such as droperidol as an anesthetic premedication, for induction of anesthesia and as an adjunct in maintenance of general and regional anesthesia. 

Analgesia - Analgesic adjunct for the maintenance of balanced general anesthesia in patients who are intubated and ventilated. 

Maintenance of anesthesia - After endotracheal intubation, decrease the infusion rate of remifentanil in accordance with the dosing guidelines in the table above. Because of the rapid onset and short duration of action of remifentanil, the rate of administration during anesthesia can be titrated upward in 25% to 100% increments or downward in 25% to 50% decrements every 2 to 5 minutes to attain the desired level of p-opioid effect. In response to light anesthesia or transient episodes of intense surgical stress, supplemental bolus doses of 1 mcg/kg may be administered every 2 to 5 minutes. At infusion rates more than 1 mcg/kg/min, consider increases in the concomitant anesthetic agents to increase the depth of anesthesia. 

Children (younger than 12 years of age) - For induction and maintenance of anesthesia in children undergoing cardiovascular surgery, a dose of 10 to 25 mcg/kg administered with 100% oxygen is recommended. Supplemental dosages of up to 25 to 50 meg are recommended for maintenance. 

Do not use oxycodone in children. Safe dosage of codeine has not been established for children younger than 3 years of age. Safety and efficacy have been established with remifentanil from birth to 12 years of age in maintenance of general anesthesia. 

Propofol can be used for induction as well as maintenance of anesthesia. It is very lipophilic and induction of anesthesia takes place within 30 seconds. After a single dose the patient awakes in approximately 5 minutes and after anesthesia by continuous intravenous administration of longer duration recovery may take 10-15 minutes. It can be used in combination with the usual range of premedications, analgesics, muscle relaxants and inhalation anesthetic agents. 

The inhalation anesthetics belong to diverse chemical classes. There main indication is the maintenance of anesthesia after intravenous induction. There are no suggestions that they interact with pharmacologically-defined receptors like some of the injectable anesthetics do and they have no specific site of action. Apparently they cause physical changes in cells such as changes in cell membrane fluidity. 

Rapid recovery and its antiemetic properties make propofol anesthesia very popular as an induction agent for outpatient anesthesia. Propofol can also be used to supplement inhalational anesthesia in longer procedures. Both continuous infusion of propofol for conscious sedation and with opioids for the maintenance of anesthesia for cardiac surgery are acceptable techniques. 

Remifentanil, recently approved for use in the United States and Europe, is the first truly ultra-shortacting opioid. Remifentanil s uifique ester linkage allows it to be rapidly degraded to an inactive carboxylic acid metabolite by nonspecific esterases found in tissue and red blood cells. Since it is not a good substrate for plasma pseudocholinesterase, deficiency of the enzyme does not influence its duration of action. Also, hepatic and renal insufficiencies do not influence remifentanil s pharmacokinetics, so it is useful when liver or kidney failure is a factor. Because of its rapid clearance following infusion, remifentanil has gained popularity as an agent for maintenance of anesthesia when an IV technique is practical. 

The use of inhalational anesthetics is generally reserved for maintenance of anesthesia. The development of an anesthetic concentration in the brain occurs more slowly with inhalational anesthetics than with IV drugs. Once an anesthetic level has been achieved, however, it is easily adjusted by controlling the rate or concentration of gas delivery from the anesthesia machine. The rate of recovery from a lengthy procedure in which inhalational agents are used is reasonably rapid, since inhalational anesthetics are eliminated by the lungs and do not depend on a slow rate of metabolism for their tissue clearance. Thus, inhalational drugs meet the requirement for a relatively prompt return of the patient s psychomotor competence. 

Increasing the inspired tension of an anesthetic gas above the maintenance tension (i.e., near the MAC value) is also an effective means of quickly establishing effective alveolar tension. This maneuver, frequently referred to as overpressure, parallels the concept of loading dose. As the desired depth of anesthesia or level of alveolar tension is achieved, the delivered tension of anesthetic must be returned to the maintenance (MAC) level to avoid overdosing the patient. 

The most common use of NjO is in combination with the more potent volatile anesthetics. It decreases the dosage requirement for the other anesthetics, thus lowering their cardiovascular and respiratory toxicities. For example, an appropriate anesthetic maintenance tension for N2O and halothane would be N2O 40% and halothane 0.5%. With this combination in a healthy patient, anesthesia is adequate for major surgery, and the dose-dependent cardiac effects of halothane are reduced. 

Preoperative IM, IV 2.5-10 mg 30-60 min before induction of general anesthesia. Adjunct for induction of general anesthesia IV 0 22-0 275 mg/kg Adjunct for maintenance of general anesthesia IV I 25-2 5 mg Diagnostic procedures w/o general anesthesia IM 2.5-10 mg 30-60 min before procedure. If needed, may give additional doses of 1.25-2.5 mg (usually by IV injection). 

An anxious 5-year-old child with chronic otitis media and a history of poorly controlled asthma presents for placement of ventilating ear tubes. General anesthesia is required for this short elective ambulatory surgery procedure. What preanesthetic medication should be administered Which of the three commonly used anesthetic techniques would you choose to use in this situation (1) inhalational anesthesia with sevoflurane for induction and maintenance in combination with nitrous oxide, (2) intravenous anesthesia with propofol for induction and maintenance of anesthesia in combination with remifentanil, or (3) balanced anesthesia using propofol for induction of anesthesia followed by a combination of sevoflurane and nitrous oxide for maintenance of anesthesia ... 

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