Propofol Alfentanil

A study in 10 healthy subjects under general anaesthesia with alfentanil, propofol and nitrous oxide/oxygen, found that an intravenous infusion of dexmedetomidine (950 to 990 nanograms/kg) increased plasma rocuro-... 

TIVA has become feasible thanks to the introduction of agents with a suitably short duration of action, including the injectable anesthetics propofol and etomidate, the analgesics alfentanil und remifentanil, and the muscle relaxant mivacurium. These drugs are eliminated within minutes after being adminster-ed, irrespective of the duration of anesthesia. 

Opioids play an important role in anesthetic practice. Opioid analgesics potentiate the efficacy of anesthetics. They can be given as part of the premedication as well as during the operation. Examples of short acting agents with high potency are fentanyl, sufentanyl, alfentanil and remifentanil. Because of their hemodynamic stability these agents can be used for patients with compromised myocardial function. Respiration must be maintained artificially and may be depressed into the postoperative period. They are usually supplemented with inhalation anesthetic, benzodiazepines or propofol. 

Several drugs are used intravenously, alone or in combination with other drugs, to achieve an anesthetic state (as components of balanced anesthesia) or to sedate patients in intensive care units who must be mechanically ventilated. These drugs include the following (1) barbiturates (thiopental, methohexital) (2) benzodiazepines (midazolam, diazepam) (3) opioid analgesics (morphine, fentanyl, sufentanil, alfentanil, remifentanil) (4) propofol (5) ketamine and (6) miscellaneous drugs (droperidol, etomidate, dexmedetomidine). Figure 25-2 shows the structures of... 

Pavlin DJ, Coda B, Shen DD, et al. Effects of combining propofol and alfentanil on ventilation, analgesia, sedation, and emesis in human volunteers. Anesthesiology 1996 84(l) 23-37. 

Usually intravenous pre-oxygenation followed by a small dose of an opioid, e.g., fentanyl or alfentanil to provide analgesia and sedation, followed by propofol or, less commonly, thiopental or etomidate to induce anaesthesia. Airway patency is maintained with an oral airway and face-mask, a laryngeal mask airway (LMA), or a tracheal tube. Insertion of a tracheal tube usually requires paralysis with a neuromuscular blocker and is undertaken if there is a risk of pulmonary aspiration from regurgitated gastric contents or from blood. 

Sedation in critical care units is used to reduce patient anxiety and improve tolerance to tracheal tubes and mechanical ventilation. Whenever possible, patients are sedated only to a level that allows them to open their eyes to verbal command oversedation is harmful. Commonly used drugs include propofol and midazolam, and opioids such as fentanyl, alfentanil, or morphine. 

Alfentanil is an ideal analgesic for focused and ambulatory interventions. In a prospective, uncontrolled study in three consecutive groups of outpatients undergoing shock-wave lithotripsy, group 1 (152 patients) had an induction dose of a combination of propofol 0.8 mg/kg and alfentanil 8 pg/kg in group 2 (78 patients) and group 3 (250 patients), the induction dose was reduced by 20%... 

In a non-comparative study of 24 consecutive outpatients undergoing extracorporeal shock-wave lithotripsy, alfentanil (initial dose 15 pg/kg followed by 0.38 pg/kg/minute) and propofol (initial dose 1 mg/kg followed by 59 pg/kg/minute) were used for sedation... 

Both alfentanil and propofol were effective and safe, provided respiratory and cardiovascular parameters were routinely monitored. 

A 35-year-old man developed recurrent respiratory depression after being given alfentanil 0.0125 mg/kg for vitreoretinal surgery (5). General anesthesia was induced with a combination of propofol, rocuronium, and alfentanil, subsequent inhalation of isoflurane, and three additional doses of alfentanil (total 0.04 mg/kg over 2 hours). The pulse oxygen saturation fluctuated and was as low as 89% 180 minutes after extubation. 

Nociti JR, Zuccolotto SN, Cagnolatl CA, Oliveira ACM, Bastos MM. Propofol and alfentanil sedation for extracorporeal shock wave lithotripsy. Rev Bras Anestesiol 2002 1 74-8. 

Nelskyla K, Korttila K, Yli-Hankala A. Comparison of sevoflurane-nitrous oxide and propofol-alfentanil-nitrous oxide anaesthesia for minor gynaecological surgery. Br J Anaesth 1999 83(4) 576-9. 

Davis PJ, Lerman J, Suresh S, McGowan EX, Cote CJ, Landsman I, Henson LG. A randomized multicenter study of remifentanil compared with alfentanil, isoflurane, or propofol in anesthetized pediatric patients undergoing elective strabismus surgery. Anesth Analg 1997 84(5) 982-9. 

ScheUer MS, Zornow MH, Saidman LJ. Tracheal intubation without the use of muscle relaxants a technique using propofol and varying doses of alfentanil. Anesth Analg 1992 75(5) 788-93. 

Klemola UM, Mennander S, Saarnivaara L. Tracheal intubation without the use of muscle relaxants remifentanil or alfentanil in combination with propofol. Acta Anaesthesiol Scand 2000 44(4) 465-9. 

Estimates of target remifentanil clinical concentrations were obtained by scaling the alfentanil concentration-response relationship for clinical responses (e.g., analgesia, surgery with low-dose propofol) by the relative potency estimate (30-fold) obtained in the EEG trial. The concordance between the observed therapeutic remifen-tanil concentration estimated from Phase 2/3 clinical trials and predicted therapeutic concentrations is depicted in Figure 31.6. In every case the predicted range... 

Operationally, anaesthetics can be classified as inhalational or intravenous. The most used compounds of this last group are thiopental, propofol and ketamine recently, new synthetic opioids related to phenylpiperidines (phentanyl and its congeners, sufentanil, alfentanil, remifentanil) are also used. 

The respiratoiy depressant effects of ketamine and morphine may be additive. The dose requirements of desflurane, etomidate, propofol and thiopental may be lower after opioid use. Opisthotonos or grand mal seizures have rarely been associated with the use of propofol with alfentanil and/or fentanyl. The effects of in-halational anaesthetics may be enhanced by opioid analgesics. 

A 71-year-old man undergoing a minor orthopaedic operation was given a 500-microgram intravenous injection of alfentanil followed by a slow injection of propofol 2.5 mg/kg. Approximately 15 seconds after the propofol, the patient developed strong bilateral fits and grimaces, which lasted for 10 seconds. Anaesthesia was maintained with nitrous oxide/oxygen and halothane and there were no other intra- or postoperative complications. The patient had no history of convulsions. Propofol has also been associated with opisthotonos (a spasm where the head and heels bend backwards and the body arches forwards) in two patients given fentanyl... 

Wittenstein U, Lyle DJR. Fits after alfentanil and propofol. Anaesthesia (1989) 44, 532-3. 

Vuyk J, Griever GER, Engbers FHM, Burm AGL, Bovill JG, Vletter AA. The interaction between propofol and alfentanil during induction of anesthesia. Anesthesiology (1994) 81,... 

IhmsenH, Albrecht S, Fechner J, Bering W, Schuttler J. The elimination of alfentanil is decreased by propofol. 2000 Annual Meeting of the American Society of Anesthesiologists, San... 

Mertens MJ, Vuyk J, Olofsen E, Bovill JG, Burm AGL. Propofol alters the pharmacokinetics of alfentanil in healthy male volunteers. Anesthesiology (2001) 94,949-57. 

Mertens MJ, Olofsen E, Burm AGL, Bovill JG, Vuyk J. Mixed-effects modeling of the influence of alfentanil on propofol pharmacokinetics. Anesthesiology (2004) 100, 795-805. 

SchwildenH, Fechner J, Albrecht S, Bering W, IhmsenH, Schuttler J. Testing and modelling the interaction of alfentanil and propofol on the EEG. EurJAnaes iesiol (2003) 20,363-72. 

Beresford BJ, Glick D, Dinwiddie SH. Combination propofol-alfentanil anesthesia for electroconvulsive therapy in patients receiving monoamine oxidase inhibitors. JECT (2004) 20, 120-2. 

A combination of alfentanil and propofol for deep procedural sedation in an emergency department was not beneficial [61 ]. It was not associated with improved pain control or recall after the procedure. A higher proportion of patients who received the combination (31 of 71) required stimulation to induce respiration. 

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