Opioids anesthesia

Although opioid anesthesia is particularly useful in patients with compromised myocardial function, the opioids depress respiration by inhibiting the responsiveness of the medullary respiratory center to PCO2 and alter the rhythm of breathing. Consequently, it is necessary to assist ventilation intraoperatively. Since respiratory depression may extend into the postoperative period as a result of drug accumulation in the tissues, the use of opioids whose clearances are slow, remain most appropriate for patients who are expected to require postoperative ventilatory care. 

Remifentanil (Ultiva) has recently gained popularity as a high-dose opioid anesthesia because (A) It induces anesthesia in patients faster than any other drug... 

Ultrarapid detoxification employs general anesthesia and opioid antagonists to accomplish withdrawal more quickly (Alvarez and Carmen del Rio 1999 Bell et al. 1999 Brewer et al. 1998 Brewer and Maksoud 1997 Gerra et al. 2000 Kleber 1998 Rabinowitz et al. 1998 SanandArranz 1999 Shreeram et al. 2001 Stephenson 1997 Strang et al. 1997). Its efficacy and safety are being studied. 

The first step in preventing PONV is reducing baseline risk factors when appropriate.6 Regional anesthesia rather than general anesthesia should be used. Opioids should be replaced... 

Naloxone (Narcan). Naloxone, like naltrexone, is a potent opioid receptor blocker. Its primary use has been to reverse opiate toxicity after an overdose. However, some physicians have found it is also useful for a process known as rapid opiate detoxification. Although opiate withdrawal is not life threatening, it can be extremely unpleasant. Most opiate addicts are fearful of the withdrawal symptoms therefore, it usually requires a slow, deliberate detoxification to keep the withdrawal symptoms in check. Rapid opiate detoxification is an alternative approach that keeps the taper and detoxification as brief as possible. In this approach, naloxone is used in conjunction with general anesthesia or a nonopiate sedative such as the benzodiazepine mid-... 

The synthesis of these compounds will be described in Section 3.1, Opioid analgesics. Besides opioids, benzodiazepines (diazepam, lorazepam, and midazolam), which have anxiolytic, sedative, and anticonvulsant effects, that cause amnesia and muscle relaxation, are frequently used to relieve patients anxiety during anesthesia. 

Concomitant narcotic administration - The respiratory depressant effect of fentanyl may persist longer than the analgesic effect. Consider the total dose of all opioid analgesics used before ordering narcotic analgesics during recovery from anesthesia. Use opioids in reduced doses initially, %to 1/3 those usually recommended. 

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. 

Administration Nalbuphine should be given as a supplement to general anesthesia only by persons specifically trained in the use of IV anesthetics and management of the respiratory effects of potent opioids. 

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. 

Opioid analgesics have always been important for the control of pain in the preoperative and postoperative periods. They are also used to supplement anesthesia... 

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. 

Opioid-induced muscle rigidity is a frequent complication of this form of anesthesia. It is most common with phenylpiperidine drugs and occurs even after low doses of fentanyl, such as those used in certain diagnostic or minor surgical procedures where a pain-free... 

The MAC requirement also is reduced by the coadministration of other CNS depressants, such as barbiturates or opioid analgesics. CNS stimulants, such as amphetamine, may elevate the partial pressure needed for anesthesia. 

Pentazocine is indicated for relief of moderate pain in patients not receiving large doses of opioids. It is also used as premedication for anesthesia and as a supplement to surgical anesthesia. 

---