Opioids: clinical use as anesthetic agents.

Opioids (narcotic analgesics) are widely used in the practice of anesthesia for preanesthetic medication, systemic and spinal analgesia, supplementation of general anesthetic agents, and as primary anesthetics. The last use is particularly widespread for major surgical operations, especially those involving patients with cardiovascular disease. The use of opioids in anesthetic doses is based on the absence of cardiac depression by the opioids. As with all anesthetic drugs, the opioids have limitations and side effects, but for the most part, these are easily managed on the basis of knowledge of their pharmacology. The key to their efficient use is careful titration of dose according to the individual patient's responses to the drug as well as to noxious stimulation. Although there is a very wide margin of safety, allowing administration of enormous doses intraoperatively when the patient's ventilation is supported mechanically, the disadvantage of using doses far in excess of the individual patient's need is a prolonged recovery from anesthesia with the risk of postoperative ventilatory depression. Titration of the dose can be facilitated by computer-controlled infusion pumps with the benefit that the recovery time from anesthetic doses can be appropriate for the individual patient and surgical procedure, and postoperative analgesia can be continued by patient-controlled analgesia, which is another example of computer-controlled opioid infusion. Although specific opioid antagonists are available, their use to antagonize residual anesthetic effects is potentially hazardous.     

Pharmacologic rationale for anesthetic agents in ambulatory practice

Patients undergoing surgery in the ambulatory setting require anesthetic agents that expedite postoperative recovery, minimize adverse side effects, and contribute to patient satisfaction. The newer anesthetic agents that are currently used in today's practice offer the flexibility needed to provide anesthesia care for a wide variety of diagnostic and therapeutic procedures performed on an outpatient basis. It is important for the perianesthesia nurse to be familiar with the anesthetic agents used in the operating room to fully understand the influence of these drugs on the patient's recovery process. The role of the perianesthesia nurse is vital in assessing the residual effects of the anesthetic agents and instituting proper nursing interventions during the patient's postanesthesia experience. This article focuses on the rationale for the use of a variety of anesthetic and related agents necessary for the provision of ambulatory anesthesia. The commonly used agents used in ambulatory anesthesia care and their influences on the continuum of care is reviewed.     

经皮内窥镜引导下胃造口术的麻醉

  目的  探讨经皮内窥镜引导下胃造口术(percutaneous endoscopic gastrostomy, PEG)的临床麻醉经验。  方法  回顾性分析北京协和医院90例PEG患者的临床资料, 并对麻醉方式、静脉麻醉药物和麻醉风险进行总结。  结果  85例采用表面麻醉+局部麻醉+静脉镇静或全麻, 其中仅1例采用气管插管全麻; 其他5例采用表面麻醉+局部麻醉。静脉麻醉药物主要为咪达唑仑、芬太尼或舒芬太尼、丙泊酚或依托咪酯, 用药剂量和方法各不相同。在PEG过程中患者血流动力学和呼吸基本平稳, 但可能发生低氧血症、高血压和心动过缓等风险。与PEG前比较, PEG期间收缩压、舒张压和心率最小值明显下降, 脉搏血氧饱和度最大值明显上升, 差异有统计学意义(P < 0.05)。  结论  PEG的麻醉方式可以采用表面麻醉+局部麻醉+静脉镇静或全麻, 但应加强麻醉管理。     

The BIS monitor: a review and technology assessment

In the administration of anesthesia, clinicians have traditionally relied on a variety of autonomic signs to assess the pharmacologic effects of anesthetic agents on the central nervous system. As any experienced clinician knows, these signs can be misleading and lead to overdosing or underdosing of anesthetic drugs. The development of a monitor to measure the bispectral index (BIS) provides anesthetists with the first clinically tested and US Food and Drug Administration-approved monitor to assess the effects of anesthesia on the cerebral cortex. This article reviews the development of the BIS monitor, compares the BIS monitor with other commonly used clinical monitors, assesses the cost-benefit from the use of this monitor, and explores some of the possible uses for this monitor outside of the operating suite.     

Postoperative ketamine analgesia in children: efficacy and safety after halothane anesthesia

This study was done to investigate the effectiveness and safety of ketamine analgesia after halothane anesthesia for surgery in children. After completion of a surgical procedure, ten children had ketamine (1 mg/kg) injected intravenously during maintenance of anesthesia with 1% halothane in a 60:40 nitrous oxide-oxygen mixture. Cardiovascular parameters measured with noninvasive oscillometry and transthoracic impedance plethysmography remained unchanged after administration of ketamine. Excellent analgesia and a calm anesthetic recovery were produced, without detectable cardiovascular depression. When ketamine and halothane are administered in combination, careful restriction of dosages of these agents is recommended. Interaction of higher doses of ketamine and halothane has been reported to produce hypotension and bradycardia, which can be avoided with use of subdissociative, analgesic doses of ketamine during light halothane maintenance before emergence. After halothane anesthesia in healthy children, ketamine may be considered a suitable alternative to narcotics for postoperative analgesia.     

Asthma: an anesthetic update. Part 3.

The effective management of the patient with asthma continues to represent a significant challenge in modern anesthesia practice. The prevalence of asthma is increasing worldwide and is the most common chronic disorder among children. Classification and treatment strategies continue to evolve as new therapies emerge. Fortunately, the incidence of bronchospastic episodes under anesthesia has declined in recent years with the development of improved anesthetic drugs and techniques. A thorough understanding of the pathogenesis of asthma will assist in developing anesthetic management plans that are patient specific and use the best treatment pathways currently available.     

Pharmacokinetics of midazolam, propofol, and fentanyl transfer to human breast milk

BACKGROUND AND OBJECTIVES: Lactating women undergoing operations requiring general anesthesia are advised to pump and discard their milk for 24 hours after the procedure. Data on anesthetic drug transfer into breast milk are limited. This study determined the pharmacokinetics of midazolam, propofol, and fentanyl transfer into milk to provide caregivers with data regarding the safety of breast milk after administration of these drugs. METHODS: Five lactating women participated in this study after providing institutionally approved written informed consent. Patients underwent premedication with midazolam before induction of anesthesia with propofol and fentanyl. Anesthesia was maintained with a potent volatile anesthetic. Milk and blood were collected before drug administration. Milk was collected 5, 7, 9, 11, and 24 hours after drug administration. Venous blood was collected at intervals up to 7 hours. Plasma and milk midazolam, propofol, and fentanyl concentrations were measured by HPLC with tandem mass spectrometric or fluorescence detection. The pharmacokinetics of drug transfer into milk was modeled with plasma pharmacokinetics. RESULTS: Plasma midazolam, propofol, and fentanyl pharmacokinetics were consistent with reports of others. In 24 hours of milk collection, averages of 0.005% (range, 0.002%-0.013%) of the maternal midazolam dose, 0.027% (0.004%-0.082%) of the propofol dose, and 0.033% (0.006%-0.073%) of the fentanyl dose were collected in milk, representing averages of 0.009%, 0.025%, and 0.039% of the respective elimination clearances. CONCLUSION: The amount of midazolam, propofol, and fentanyl excreted into milk within 24 hours of induction of anesthesia provides insufficient justification for interrupting breast-feeding.     

Intravenous narcotics in the ICU

In summary, there are now available very potent narcotics, with small side effect liability. Critical care physicians should be experts in administration of intravenous narcotics and should understand the concepts behind different methods of administration. Much more patient satisfaction and safety can be obtained if as much attention is paid to how a drug is administered as to its pharmacologic actions. Intravenous administration allows rapid and almost complete control of desired effect. Intravenous access is universally available in the ICU population, and we should take every advantage of it.     

Use of propofol and other nonbenzodiazepine sedatives in the intensive care unit.

Sedatives continue to be used on a routine basis in critically ill patients. Although many agents are available and some approach an ideal, none are perfect. Patients require continuous reassessment of their pain and need for sedation. Pathophysiologic abnormalities that cause agitation, confusion, or delirium must be identified and treated before unilateral administration of potent sedative agents that may mask potentially lethal insufficiencies. The routine use of standardized and validated sedation scales and monitors is needed. It is hoped that reliable objective monitors of patients' level of consciousness and comfort will be forthcoming. Each sedative agent discussed in this article seems to have a place in the ICU pharmacologic armamentarium to ensure the safe and comfortable delivery of care. Etomidate is an attractive agent for short-term use to provide the rapid onset and offset of sedation in critically ill patients who are at risk for hemodynamic instability but seem to need sedation or anesthesia to perform a procedure or manipulate the airway. Ketamine administered through intramuscular injection or intravenous infusion provides quick, intense analgesia and anesthesia and allows patients to tolerate limited but painful procedures. The risk/benefit ratio associated with the use of this neuroleptic agent must be weighed carefully. Ketamine is contraindicated in patients who lack normal intracranial compliance or who have significant myocardial ischemia. Barbiturates are reserved mainly to induce coma in patients at risk for severe CNS ischemia, which frequently is associated with refractory intracranial hypertension, or in patients with status epilepticus. When administered in high doses, these drugs have prolonged sedative and depressant effects. Judicious hemodynamic monitoring is required when barbiturate coma is induced. Haloperidol is indicated in the treatment of delirium. Patients should be monitored for extrapyramidal side effects and, when they require higher doses, for potential electrocardiographic prolongation of the QT interval. Dexmedetomidine may evolve into an agent with qualities comparable with midazolam and propofol, and it may even become a drug of choice in select patients. Further study is required, however. Propofol has many of the qualities of an ideal sedative agent. Benzodiazepines and narcotics often are used in concert with propofol to provide reliable amnesia and to relieve pain, respectively. Propofol frequently causes hypotension when administered as a bolus or infusion, particularly in patients with limited cardiac reserve or hypovolemia. More data must be obtained to identify potential deleterious effects of hypertriglyceridemia, and further evaluation of the potential benefits in certain patient populations, such as neurosurgical patients, is needed.     

Complete Recovery From Intractable Complex Regional Pain Syndrome, CRPS-Type I, Following Anesthetic Ketamine and Midazolam

Objective: To describe the treatment of an intractable complex regional pain syndrome I (CRPS-I) patient with anesthetic doses of ketamine supplemented with midazolam.
Methods: A patient presented with a rapidly progressing contiguous spread of CRPS from a severe ligamentous wrist injury. Standard pharmacological and interventional therapy successively failed to halt the spread of CRPS from the wrist to the entire right arm. Her pain was unmanageable with all standard therapy. As a last treatment option, the patient was transferred to the intensive care unit and treated on a compassionate care basis with anesthetic doses of ketamine in gradually increasing (3–5 mg/kg/h) doses in conjunction with midazolam over a period of 5 days.
Results: On the second day of the ketamine and midazolam infusion, edema, and discoloration began to resolve and increased spontaneous movement was noted. On day 6, symptoms completely resolved and infusions were tapered. The patient emerged from anesthesia completely free of pain and associated CRPS signs and symptoms. The patient has maintained this complete remission from CRPS for 8 years now.
Conclusions: In a patient with severe spreading and refractory CRPS, a complete and long-term remission from CRPS has been obtained utilizing ketamine and midazolam in anesthetic doses. This intensive care procedure has very serious risks but no severe complications occurred. The psychiatric side effects of ketamine were successfully managed with the concomitant use of midazolam and resolved within 1 month of treatment.
This case report illustrates the effectiveness and safety of high-dose ketamine in a patient with generalized, refractory CRPS.     

腰-硬联合麻醉用于高龄患者的临床经验

目的：总结腰椎-硬膜外（腰-硬）联合麻醉用于高龄（75岁以上）患者的临床经验。方法对重庆市第三人民医院2013年1～11月56例采用腰-硬联合麻醉的高龄患者的临床资料进行回顾性分析,重点收集麻醉起效和维持时间,麻醉中血流动力学变化情况,麻醉中辅助药物使用情况及并发症等资料。结果蛛网膜下腔注药后平均（54±10）s开始出现麻醉平面,平均（5．8±1．2）min后麻醉平面固定,阻滞平面上界胸8～10。与麻醉前基础值比较,麻醉后平均动脉压有所下降,差异有统计学意义（P＜0．05）,但都在正常范围。麻醉中患者生命体征平稳,全部在腰-硬联合麻醉下顺利完成手术。术中有1例患者因平均动脉压（MAP）过低给予麻黄碱纠正;有1例患者MAP升高超过麻醉前基础值30％进行降压处理;另有1例患者出现心率低于55次/分,给予阿托品0．5 mg后纠正,其余患者术中生命体征平稳。麻醉中未观察到明显呼吸抑制,脉搏氧饱和度均维持在96％以上。有9例患者术中经硬膜外导管追加了局部麻醉药物,有21例患者术中给予芬太尼、咪达唑仑或丙泊酚辅助。患者术毕未见恶心、呕吐、头痛等现象,未观察到明确麻醉并发症。结论腰-硬联合麻醉可安全用于高龄患者,其起效迅速,效果完善,麻醉中生命体征稳定,充分的麻醉前准备和完善的麻醉管理措施,有助于保障麻醉的安全性。     

Procedural sedation in the acute care setting

Many patients require sedation during diagnostic or therapeutic procedures. Ideally, procedural sedation minimizes the patient's awareness and discomfort while maintaining the patient's safety. Appropriate monitoring by trained personnel is the key to successful procedural sedation. These techniques should be used only by health care professionals skilled in managing complications, including cardiorespiratory compromise. It is important to take a complete history and perform a thorough physical examination, paying special attention to the selection of pharmacologic agents. Common sedative agents include etomidate, ketamine, fentanyl, and midazolam. These have become the agents of choice for procedural sedation because of their ease of use, predictable action, and excellent safety profiles. All patients requiring procedural sedation should be monitored by qualified staff at the bedside until they have recovered to an age-appropriate baseline mental status and function.     

AANA Journal course: update for nurse anesthetists--anesthesia for the ruptured globe

Anesthesia for the patient with a perforated globe can be complicated. Cognizance of the anatomy and physiology of the eye, including maintenance of intraocular pressure, is essential for the development of an anesthetic plan. Since the induction phase of anesthesia is the most critical period during which intraocular pressure is affected, understanding the pharmacology of the various anesthetic agents and their effects on the eye is important. To avoid increasing intraocular pressure, a smooth, atraumatic induction is desired. However, methods to achieve this end may place the patient at risk for aspiration. Various techniques that attempt to accomplish this goal are described, including the use of narcotics, lidocaine, nitroglycerin, alpha (alpha 2) agonism, beta (beta) adrenergic and calcium channel blockades, plus the laryngeal mask airway.     

Therapeutic Modalities for the Prophylactic Management of Postoperative Nausea and Vomiting

The occurrence of postoperative nausea and vomiting (PONV) remains one of the most common complications after general anesthesia. The causes of PONV are multimodal, involving several physiologic pathways that stimulate the vomiting center, including the chemoreceptor trigger zone, the gastrointestinal tract, the vestibular system, the cerebral cortex, and the midbrain. Significant research has been published focusing on the use of different pharmacologic agents and varying anesthetic techniques to prevent and manage PONV. The addition of therapeutic modalities to the arsenal of prophylactic management techniques may decrease patient incidence of PONV by directing treatment to various pathways that stimulate the vomiting center. The purpose of this article is to review briefly the literature and discuss three therapeutic modalities for preventing PONV: perioperative oxygen administration, perioperative intravenous fluid administration, and differing fasting protocols.     

Chronic cancer pain management with the Du Pen epidural catheter

Chronic epidural administration of narcotics and/or local anesthetics is sometimes required in those few patients where utilization of systemic narcotics and appropriate adjuvant medications is unsuccessful in controlling intractable cancer pain. The Du Pen epidural catheter (Davol, Inc.) a silicone-based tunneled catheter modeled after the Hickman central venous catheter, has provided a safe, reliable means of long-term administration of drugs to the epidural space in over 400 patients to date. A systematic approach to the pharmacology of epidural pain control includes drug choice, bolus dosing versus infusion, volume guidelines, and titration protocols. Utilization of local anesthetics in combination with narcotics allows for enhanced pain relief in those patients refractory to narcotics as is frequently the case with neurogenic involvement. Follow-up care of patients receiving epidural narcotic with or without local anesthetic can be accomplished by a trained home cae team. Successful epidural pain management requires thorough patient and caregiver education, frequent pain assessment, and monitoring of side effects, with close collaboration between patient/family, pharmacist, home care nurse, and physician.     

Prolonged isoflurane anesthesia in status asthmaticus

We report a case of status asthmaticus that was unresponsive to the usual agents. The use of an inhalational anesthetic agent allowed us to ventilate the patient with lower inspiratory pressures; however, lasting improvement did not occur until she mobilized large quantities of secretions. To our knowledge, this is the first clinical report on the use of isoflurane anesthesia to treat severe asthma. Despite prolonged administration, there were no significant side-effects. This case demonstrates both the benefits and limitations of such therapy.     

Sedation and analgesia in the pediatric patient

The administration of sedation and analgesia for pediatric gastrointestinal procedures has become routine but is not standardized. For the most part, pediatric endoscopists are encouraged to use their clinical judgment to select between using intravenous (IV) sedation or general anesthesia on an individual patient basis. Commonly administered IV sedation regimens in children combine benzodiazepines with narcotics, but anesthesiologist administered propofol sedation is gaining acceptance among pediatric gastroenterologists. Guidelines for patient monitoring and new technologic advances may help to ensure patient safety for children undergoing endoscopic procedures, no matter what sedation regimen is used.     

AANA journal course. Update for nurse anesthetists. Aspiration prophylaxis: is it time for changes in our practice?

Pulmonary aspiration of gastric contents during anesthesia is a complication that is fortunately rare, yet potentially catastrophic. Despite its infrequency, techniques geared toward preventing this serious outcome influence many of our routine practices and beliefs. Reports on large-scale clinical studies have opened new insights and questions about the effectiveness of long-standing anesthetic practices. These include conventional beliefs about preoperative fasting guidelines, acceptable gastric fluid volumes and pH, effective pharmacologic interventions, risk factors for pulmonary aspiration, and preventative anesthetic techniques such as rapid-sequence induction. This AANA Journal course outlines current knowledge as to the incidence, risk factors, and efficacy of practices geared toward preventing aspiration. It is anticipated that this review will stimulate discussions regarding possible changes in the anesthetic management of patients in individual practice settings.     

Pharmacologic agents in the management of pheochromocytoma

Medical management of pheochromocytoma involves the use of many therapeutic agents. Phenoxybenzamine HCl (Dibenzyline), an alpha-adrenergic blocking agent, at 40 to 80 mg per day can control the disease in most patients. Use of this drug up to the time of operation is controversial. Beta-adrenergic receptor blockade with propranolol is indicated only after adequate alpha-adrenergic blockade in patients with tachycardia and catecholamine-induced arrhythmias. Alpha-methylparatyrosine (Metyrosine), which decreases catecholamine synthesis, is a new drug recently released for the treatment of pheochromocytoma when surgery is contraindicated or in cases of malignant pheochromocytoma. The use of a combination of anesthetic agents, such as nitrous oxide, thiopental, narcotics, and enflurane, ensures smooth induction of anesthesia in most cases. Careful and prompt control of hypertensive crises with sodium nitroprusside and of arrhythmias with propranolol and lidocaine are critical to the success of surgery.     

A review of recent cardioactive and vasoactive drugs in anesthesia

This survey article provides a current update on a variety of new cardioactive and vasoactive drugs that have recently been added to the anesthesia armamentarium. Included are discussions of pharmacologic agents, their effects on cardiovascular physiology, and mechanisms of each as they relate to specific uses of anesthesia care and general clinical practice. The cardioactive and vasoactive drugs discussed encompass sympathetic agonists, sympathetic antagonists, vasodilators, and calcium channel blockers.