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PubMed1997

Midazolam versus propofol for long-term sedation in the ICU: a randomized prospective comparison.

OBJECTIVE: To compare the efficacy, safety, and cost of midazolam and propofol in prolonged sedation of critically ill patients. DESIGN: Randomized, prospective study. SETTING: General intensive care unit (ICU) in a 1100-bed teaching hospital. PATIENTS: 67 critically ill, mechanically ventilated patients. INTERVENTIONS: Patients were invasively monitored and mechanically ventilated. A loading dose [midazolam 0.11 +/- 0.02 (SEM) mg.kg-1, propofol 1.3 +/- 0.2 mg.kg-1] was administered, followed by continuous infusion, titrated to achieve a predetermined sedation score. Sedation was continued as long as clinically indicated. MEASUREMENTS AND RESULTS: Mean duration of sedation was 141 and 99 h (NS) for midazolam and propofol, respectively, at mean hourly doses of 0.070 +/- 0.003 mg.kg-1 midazolam and 1.80 +/- 0.08 mg.kg-1 propofol. Overall, 68% of propofol patients versus 31% of midazolam (p < 0.001) patients had a > 20% decrease in systolic blood pressure after the loading dose, and 26 versus 45% (p < 0.01) showed a 25% decrease in spontaneous minute volume. Propofol required more daily dose adjustments (2.1 +/- 0.1 vs 1.4 +/- 0.1, p < 0.001). Nurse-rated quality of sedation with midazolam was higher (8.2 +/- 0.1 vs 7.3 +/- 0.1 on a 10-cm visual analog scale, p < 0.001). Resumption of spontaneous respiration was equally rapid. Recovery was faster after propofol (p < 0.02), albeit with a higher degree of agitation. Amnesia was evident in all midazolam patients but in only a third of propofol patients. The cost of propofol was 4-5 times higher. CONCLUSIONS: Both drugs afforded reliable, safe, and controllable long-term sedation in ICU patients and rapid weaning from mechanical ventilation. Midazolam depressed respiration, allowed better maintenance of sedation, and yielded complete amnesia at a lower cost, while propofol caused more cardiovascular depression during induction.

Adult↗
PubMed1996

Extrahepatic glucuronidation of propofol in man: possible contribution of gut wall and kidney.

OBJECTIVE: Results from clinical pharmacokinetic studies of propofol indicate that this i.v. anaesthetic agent may undergo significant extrahepatic glucuronidation. We have investigated whether glucuronidation of propofol takes place in the kidney and/or the gut wall. First, propofol concentrations were measured in arterial (radial artery) and portal venous blood of 12 cirrhotic patients with trans internal jugular porto-systemic shunting (TIPSS). RESULTS: In 7 of the 12 patients arterial propofol concentrations were higher than portal venous concentrations. In the remaining patients, propofol concentrations were higher in the portal vein than the radial artery. Since an additional study in 5 patients anaesthetized with propofol while undergoing cholecystectomy showed propofol and an acid-labile conjugate of it in bile, it is difficult to interpret the results in patients with TIPSS due to the possibility of enterohepatic cycling. Next, in vitro studies with human liver (n = 5), kidney (n = 5) and small intestinal (n = 5) microsomes showed that all three tissues were capable of forming propofol glucuronide. Vmax for propofol glucuronidation was approximately 3 to 3.5 times higher in kidney (5.56 nmol.min-1.mg-1 protein) than liver (1.80 nmol.min-1.mg-1 protein) and small intestine (1.61 nmol.min-1.mg-1 protein). CONCLUSION: Based on these in vitro results, it is concluded that extrahepatic glucuronidation in the small intestine and especially in the kidney may contribute to the overall glucuronidation of propofol in man.

Adult↗
PubMed2003

Propofol inhibits lidocaine metabolism in human and rat liver microsomes.

PURPOSE: When two drugs are metabolized by similar P450 isoforms, one drug inhibits the metabolism of the other when both the present. The metabolism of lidocaine and propofol can be mediated by similar P450 isoforms. Therefore, we investigated the relationship in the metabolism between lidocaine and propofol in both rat and human liver microsomal P450 (CYP) systems in vitro. METHODS: (1) Propofol, 4 micro g.ml(-1), as the substrate and lidocaine (between 0.5 and 8 micro g.ml(-1)) and (2) lidocaine, 4.7 micro g.ml(-1), as the substrate and propofol (between 0.5 and 40 micro g.ml(-1)) were reacted separately with human and rat microsomes. The concentrations of lidocaine, its major metabolite (monoethylglycinexylidide, MEGX) and propofol were measured using high-pressure liquid chromatography. The metabolism of lidocaine was presented as a reaction activity (MEGX/lidocaine). RESULTS: The dose-dependent inhibitory effects of propofol on lidocaine metabolism were observed in both the human and rat groups. The IC50 (the concentration producing 50% maximal inhibition) of propofol was 5.0 micro g.ml(-1) and 0.70 micro g.ml(-1) in the human and the rat groups, respectively. The propofol concentration of 5.0 micro g.ml(-1) is within the range of clinical doses for humans. On the other hand, lidocaine did not change propofol metabolism. CONCLUSION: Propofol possesses a dose-dependent inhibitory effect on the metabolism of lidocaine in both human and rat CYP systems in vitro.

Anesthetics, Local↗
PubMed2005

How to decrease pain at rapid injection of propofol: effectiveness of flurbiprofen.

PURPOSE: Many studies have been conducted on how to decrease propofol injection pain, but none has been completely successful. In the present study, the most effective method was investigated by adding lidocaine or a nonsteroidal antiinflammatory drug or by changing the solvent. METHODS: A total of 250 patients scheduled for general anesthesia were divided into five groups. Anesthesia was induced with intravenous administration of flurbiprofen 50 mg followed immediately by propofol in a long-chain triglyceride (LCT) 2 mg.kg(-1) (flurbiprofen group, n = 50), flurbiprofen 50 mg followed by propofol LCT 2 mg.kg(-1) 1 min later (flurbiprofen 1 group, n = 50), 2% lidocaine 40 mg followed immediately by propofol LCT 2 mg.kg(-1) (lidocaine group, n = 50), propofol LCT 2 mg.kg(-1) alone (LCT group, n = 50), or propofol in a mixture of medium-chain triglyceride (MCT) and LCT 2 mg.kg(-1) (MCT/LCT group, n = 50). Pain at injection was assessed 10 and 20 s after starting the propofol infusion. RESULTS: The numbers of patients with severe and mild pain were larger in the order: LCT group (10 and 31 patients, respectively) > flurbiprofen 1 group (3 and 19) > or = MCT/LCT group (1 and 14) > or = lidocaine group (2 and 11) > flurbiprofen group (0 and 0). CONCLUSIONS: Flurbiprofen 50 mg i.v. just before propofol injection completely abolished propofol injection pain. When it was administered 1 min before propofol injection it was less effective.

Adult↗
PubMed1996

Propofol at conscious sedation doses produces mild analgesia to cold pressor-induced pain in healthy volunteers.

STUDY OBJECTIVE: To determine whether subanesthetic doses of propofol have analgesic effects in healthy volunteers. DESIGN: Prospective, double-blind, placebo-controlled, randomized, crossover trial. SETTING: Human psychomotor performance laboratory within our anesthesia and critical care department. SUBJECTS: 12, non-drug abusing volunteers, aged 22 to 38 years. INTERVENTIONS: Five drug conditions were used in which a loading injection was followed by a 20-minute infusion period: placebo [saline (Intralipid)] injection, Intralipid infusion; propofol 0.125 mg/kg injection, propofol 12.5 mcg/kg/min infusion; propofol 0.25 mg/kg injection, propofol 25 mcg/kg/min infusion; propofol 0.5 mg/kg injection, propofol 50 mcg/kg/min infusion; fentanyl 1.4 mcg/kg injection (positive control), Intralipid infusion. Five minutes into the infusion period and 115 minutes after the infusion period was terminated, subjects immersed their forearms in ice-cold water for three minutes while pain assessments were recorded. MEASUREMENTS AND MAIN RESULTS: Propofol at the two higher doses during part of the first immersion produced a significant reduction (p < 0.05) in pain intensity and bothersomeness ratings. However, relative to fentanyl, the analgesia was mild. Propofol did not affect any ratings on the 15-item short-form McGill Pain Questionnaire, whereas fentanyl reduced 10 of the ratings. CONCLUSION: Our laboratory results are consistent with the commonly accepted clinical practice of supplementing propofol with an opioid in conscious sedation procedures to provide a satisfactory level of pain relief.

Adult↗
PubMed2004

Remifentanil used to supplement propofol does not improve quality of sedation during spontaneous respiration.

STUDY OBJECTIVE: To evaluate whether the use of remifentanil to supplement propofol during spontaneous respiration confers any benefits in terms of quality of sedation and recovery, or in terms of reduction in propofol requirements. DESIGN: Prospective, randomized, double-blind study. SETTING: University hospital. PATIENTS: 50 ambulatory adult ASA physical status I and II patients scheduled for total colonoscopy. INTERVENTIONS: Patients were randomized to receive either propofol alone or propofol plus remifentanil 0.1 microg/kg/min, while independently maintaining spontaneous respiration. MEASUREMENTS: Cardiovascular and respiratory variables were measured before induction and at 1-minute intervals thereafter. Recovery from anesthesia was assessed using simple verbal commands and the Steward Post Recovery Score. Patient satisfaction was measured with a visual analog scale. Computer simulation was used to calculate the effect-site concentrations of propofol and remifentanil. MAIN RESULTS: The depressant effects on blood pressure and respiratory function were significantly higher when propofol and remifentanil were combined. Although the addition of remifentanil resulted in a decrease of propofol usage, recovery of anesthesia was faster and patient satisfaction was higher when using propofol alone. CONCLUSIONS: The addition of remifentanil to propofol during spontaneous ventilation offered no benefits compared with the use of propofol alone.

Adjuvants, Anesthesia↗
PubMed2005

Propofol-mediated impairment of CA1 long-term potentiation in mouse hippocampal slices.

Propofol (2,6-diisopropylphenol) is a short-acting intravenous anesthetic. Propofol is known to impair maintenance of long-term potentiation (LTP) in synaptic responses from Schaffer collateral-commissural (SC) pathway to CA1 pyramidal cells in the hippocampus, but the threshold concentration of propofol needed to elicit this action is unknown. The actions of propofol in vivo (e.g., amnesia, sedation, hypnosis and immobility) depend on its concentration, and thus it is necessary to determine the concentration required to impair CA1 LTP in order to assess the impact of impairment in vivo. In the present study, we investigated the effects of various concentrations of propofol on synaptic plasticity, primarily by measuring LTP at SC pathway to CA1 pyramidal cell synapses in mouse hippocampal slices. Continuous application of 50 microM propofol from 20 min before tetanus stimulation suppressed potentiation of the synaptic responses by tetanus stimulation. The suppression was pronounced from 10 min post-tetanus and about 55% suppression of the potentiation was observed at 60 min after tetanus. Propofol at 5 or 20 microM did not have this effect. The presence of gamma-aminobutyric acid type A (GABA(A)) receptors antagonist, picrotoxin, abrogated the suppression of LTP by 50 microM propofol. Propofol 50 microM did not affect long-term depression (LTD). These results suggest that the suppression of hippocampal CA1 LTP via GABA(A) receptors requires a much higher propofol concentration compared with that needed to induce amnesia.

Action Potentials↗
PubMed2006

Propofol exerts protective effects on the acute lung injury induced by endotoxin in rats.

Acute lung injury (ALI) is a major culprit of mortality in endotoxemia. Propofol has been commonly used in critical ill patients for sedation. This experiment attempted to elucidate the effects and possible mechanisms of propofol on the ALI induced by endotoxin. Experimentations were carried out using anesthetized, ventilated rats and isolated perfused rat lungs. Endotoxemia was induced by intravenous lipopolysaccharide (LPS, 10 mg kg(-1)). Various groups of rats received infusion of physiological saline solution (PSS) and LPS. Five min after LPS, propofol at low dose (5 mg kg(-1)h(-1)) or high dose (10 mg kg(-1)h(-1)) was infused for 6h. In isolated perfused rat lungs, PSS, LPS, and propofol (30 or 60 mg kg(-1)) were added into the perfusion circuit. During or after 6h observation, we determined the lung weight (LW)/body weight ratio, LW gain, exhaled nitric oxide (NO) and protein concentration in broncheoalveolar lavage. Lung pathology was evaluated to quantify the lung injury score. Plasma nitrate/nitrite, methyl guanidine (MG), tumor necrosis factor(alpha), and interleukin-1(beta) were examined. Blood leukocytes were counted. Capillary filtration coefficient (K(fc)) was obtained in isolated perfused lungs. Posttreatment of propofol at low or high dose attenuated or prevented the extent of ALI. It also reduced the plasma nitrate/nitrite, MG, and pro-inflammatory cytokines including tumor necrosis factor(alpha) (TNF(alpha)) and interleukin-1(beta) (IL-1(beta)). In the isolated perfused rat lungs, propofol significantly reduced the LPS-induced increase in K(fc). This agent did not affect the leukocytopenia caused by LPS. Accordingly, the effects of propofol on the ALI were not related to leukocyte activation or sequestration. Our results suggest that propofol exerts protective effect on the endotoxin-induced ALI. The mechanisms of actions may be mediated through inhibition on the release of pro-inflammatory cytokines, free radicals and NO. In addition, propofol abrogates the microvascular leakage of water and protein in the lungs. The results imply that the use of propofol in critically ill is not only for sedation, but also useful for the prevention of inflammatory progression and lung damage.

Acute Disease↗
PubMed1998

Modulatory and direct effects of propofol on recombinant GABAA receptors expressed in xenopus oocytes: influence of alpha- and gamma2-subunits.

Propofol (2,6-diisopropylphenol) is an intravenous general anaesthetic which can directly activate and positively modulate the GABAA receptor. The effects of propofol on human recombinant GABAA receptors were studied in Xenopus oocytes expressing either alpha1beta2, alpha1beta2gamma2L, or alpha2beta2gamma2L receptor isoforms. In all receptor isoforms tested, propofol was able to potentiate the GABA-activated currents in a concentration-dependent manner. Although propofol potentiated both alpha1beta2 and alpha1beta2gamma2L receptor isoforms with equal affinity, the efficacy of propofol potentiation was markedly greater in the alpha1beta2 receptor isoform. In contrast, potentiation of the alpha2beta2gamma2L receptor isoform by propofol occurred with higher affinity and lower efficacy than in the alpha1beta2gamma2L receptor isoform. Propofol directly activated all three receptor isoforms in a concentration dependent manner. Addition of the gamma2L subunit subtype to the alpha1beta2 receptor isoform decreased receptor sensitivity to direct activation by propofol. Replacement of the alpha1-subunit subtype with the alpha2-subunit subtype increased receptor sensitivity to propofol's direct effects. These results suggest that the alpha-and gamma2L-subunit subtypes each have the ability to influence both the direct and modulatory actions of propofol on GABAA receptor function.

Anesthetics, Intravenous↗
PubMed2004

Target-controlled propofol infusion during monitored anesthesia in patients undergoing ERCP.

BACKGROUND: A target-controlled infusion system automatically adjusts the rate of infusion of propofol to maintain a desired (target) concentration. The aim of this study was to determine whether administration of propofol with a target-controlled infusion system could improve the sedation of patients undergoing ERCP. METHODS: A total of 205 consecutive patients undergoing ERCP were sedated by using a propofol target-controlled infusion system by an anesthesiologist. The target plasma concentration of propofol ranged from 2 to 5 microg/mL. A bolus dose of fentanyl (50-100 mcg) was administered if signs of insufficient analgesia were observed at the maximum target concentration of propofol allowed. The technical difficulty of ERCP was graded on a scale from 1 (least difficult) to 5 (most difficult). RESULTS: The mean dosages of propofol and fentanyl administered were 465 (245) mg and 59 (23) mcg, respectively. The total dose of propofol administered and the mean duration of ERCP were related to the degree of difficulty of the procedure. No severe complication was observed; mean time to discharge was 31 (12) minutes. Time to discharge was not influenced by the difficulty of ERCP or by the total dose of propofol administered. CONCLUSIONS: A target-controlled infusion system for administration of propofol provides safe and effective sedation during ERCP. Further studies are needed to determine the cost-effectiveness and the safety profile for infusion of propofol with a target-controlled infusion system by a nonanesthesiologist during ERCP.

Adult↗
PubMed2000

The use of propofol for its antiemetic effect: a survey of clinical practice in the United States.

STUDY OBJECTIVES: To investigate the use of propofol by anesthesiologists for its antiemetic effect and to compare our findings with published evidence. DESIGN: Anonymous survey of U.S. anesthesiologists. SETTING: American Society of Anesthesiologists' annual meeting. MEASUREMENTS AND MAIN RESULTS: One hundred fifty anesthesiologists were surveyed on how they use propofol to achieve an antiemetic effect. A large majority (84%) of the anesthesiologists surveyed stated they used propofol for its antiemetic effect: 63% of those used propofol for induction only for cases lasting <1 h to achieve an antiemetic effect. In addition 37% used a "sandwich" technique, using propofol at the beginning and end of a case for a similar purpose. There is evidence that the antiemetic effect of propofol is associated with a defined plasma concentration range; mean, 343 ng/mL (10-90% confidence intervals [CI] 200-600 ng/mL). Simulation data demonstrated that after propofol 2 mg/kg, its concentration will drop below 350 ng/mL at 32 min. After 2 mg/kg and 20 mg within 10 min of the end of surgery, its concentration will drop below 350 ng/mL by 7 min after the 20 mg bolus dose. This finding suggests that the plasma concentrations of propofol, when used in these cases, will be below the effective range of antiemetic effect. CONCLUSIONS: Many anesthesiologists used propofol for its antiemetic effect. There is strong evidence for its antiemetic efficacy after anesthesia maintained by a propofol infusion and also for its use in the postanesthesia care unit (PACU). However, there is little evidence to support its use purely at induction of anesthesia or as part of a "sandwich" technique in an attempt to reduce postoperative nausea and vomiting. This is especially true in cases lasting longer than a few minutes.

Anesthesia, Intravenous↗
PubMed2001

A small dose of midazolam decreases the time to achieve hypnosis without delaying emergence during short-term propofol anesthesia.

STUDY OBJECTIVE: To evaluate the effect of a small dose of midazolam (10 microg kg(-1)) on induction and emergence during short-term propofol anesthesia and to investigate the effects of subsequent administration of flumazenil. DESIGN: Double-blinded, prospective, randomized study. SETTING: Operating room of a medical college hospital. PATIENTS: 30 male ASA physical status I and II patients (ages 51 to 75) scheduled for minor surgery under spinal anesthesia. INTERVENTIONS: Patients were randomly allocated to one of three groups: the placebo-propofol-placebo (PP) group, the midazolam-propofol-placebo (MP) group, or the midazolam-propofol-flumazenil (MF) group. After administering placebo or midazolam (10 microg kg(-1)), propofol 250 microg kg(-1) min(-1) was infused. Immediately after confirming that the patient was hypnotized, we terminated the propofol infusion and administered placebo or flumazenil (5 microg kg(-1)). MEASUREMENTS: The dose and the times required to achieve hypnosis (the first endpoint) and to emerge from anesthesia (the second endpoint). The plasma concentration at each endpoint was determined. MAIN RESULTS: Midazolam significantly decreased the dose and time needed to achieve hypnosis [PP vs. MP, 66 +/- 14 vs. 48 +/- 15 mg, 260 +/- 55 vs. 179 +/- 44 sec, respectively (mean +/- SD)]. Thus, the plasma concentration of propofol at hypnosis was significantly lower (PP vs. MP, 3.31 +/- 0.78 vs. 2.41 +/- 0.57 microg mL(-1)). The time to emerge from anesthesia was not prolonged by midazolam, and was further shortened by administration of flumazenil (PP, MP vs. MF, 237 +/- 77, 207 +/- 71 s vs. 126 +/- 56 sec, respectively). Flumazenil also reversed the reduction in propofol concentration induced by midazolam at emergence (PP, MP, and MF, 0.54 +/- 0.17, 0.37 +/- 0.15, and 0.59 +/- 0.22 microg mL(-1), respectively). CONCLUSIONS: Coadministration of 10 microg kg(-1)midazolam decreases the dose and time required to achieve hypnosis with propofol induction without delaying emergence from anesthesia. Additional administration of flumazenil further shortens the time to emerge from midazolam-propofol anesthesia.

Adjuvants, Anesthesia↗
PubMed1999

The effect of a dissociative dose of ketamine on the bispectral index (BIS) during propofol hypnosis.

STUDY OBJECTIVE: To compare the effect of a standardized stimulus during propofol-only hypnosis on the bispectral index (BIS) value with the effect of the injection of local anesthesia for surgery during ketamine plus propofol hypnosis (dissociative monitored anesthesia care). To determine whether ketamine increases the level of propofol hypnosis when used in dissociative doses. DESIGN: Descriptive case study. SETTING: Private practice office plastic surgery suites. PATIENTS: 30 nonpremedicated ASA physical status I and II adult female (23) and male (7) patients scheduled for elective cosmetic surgery. INTERVENTIONS: Hypnosis was induced via slow (60 to 80 drops [gtts]/min), dilute (5 mg/ml) propofol solution. Hypnosis was induced using the BIS monitor as an adjunct to traditional vital signs and verbal contact. Patients were engaged in conversation and note was taken of the BIS value when verbal contact was lost and when BIS appeared to stabilize (BIS1). A standardized stimulus (0.3 ml 1% lidocaine plain via 30-gauge needle) was applied to the area of the supraorbital nerve. Note was taken of the highest BIS value (BIS2) in the patient response. The BIS returned to baseline hypnosis (BIS1) and a 50-mg dissociative dose (independent of body weight) of ketamine was administered. Two minutes were allowed to elapse and then the surgeon was allowed to inject the local anesthesia for the proposed surgery. Note was taken of the BIS value (BIS3) in response to the surgeon's injection. MEASUREMENTS AND MAIN RESULTS: The average delta (BIS2 - BIS1) was 9.5 + 6.9. Patients did not move in response to the surgeon's injection: BIS3 = BIS1. When movement occurred, the injection was terminated and additional ketamine was given before resuming the injection. Sixteen patients received ketamine 50 mg, 12 received ketamine 100 mg, one received ketamine 150 mg, and one received ketamine 200 mg. Men required an average 19% less propofol than women in this group. CONCLUSION: This study demonstrated a positive BIS response to a standardized local anesthetic stimulus during propofol-only hypnosis and a zero response during ketamine plus propofol hypnosis (dissociative anesthesia). Ketamine administered in dissociative doses does not deepen the level of propofol hypnosis. Hypnosis alone does not imply general anesthesia. Patients move in response to inadequate local anesthesia. Because the ketamine analgesia is only transitory and the primary analgesia is not given intravenously, propofol-ketamine technique is not a total intravenous anesthetic technique (TIVA). Instead, propofol-ketamine technique may be classified as a form of monitored anesthesia care (MAC).

Adult↗
PubMed1999

Insertion of the cuffed oropharyngeal airway (COPA) with propofol or sevoflurane in adults.

STUDY OBJECTIVES: To compare the respiratory depressant effects of propofol and sevoflurane used to facilitate the placement of the cuffed oropharyngeal airway (COPA), and to evaluate the effectiveness of the COPA in supporting positive pressure ventilation during anesthetic-induced apnea. DESIGN: Randomized, single-blinded study. SETTING: University hospital. PATIENTS: 60 ASA physical status I and II adult patients scheduled for elective surgery with general anesthesia. INTERVENTIONS: Patients were induced either with spontaneous inhalation of 5% sevoflurane or with propofol 2.0 mg/kg intravenously (i.v.) followed by a continuous infusion of 170 micrograms kg-1 min-1. If the propofol patient had a tight jaw in 90 seconds, additional propofol (0.5 mg/kg) was administered and the infusion rate was increased to 200 micrograms kg-1 min-1. The COPA was placed as soon as the jaw was sufficiently relaxed to allow its insertion into the mouth. MEASUREMENTS AND MAIN RESULTS: The median (range) time to the COPA placement were 90 seconds (30 to 150 sec) and 120 seconds (60 to 210 sec) with propofol and sevoflurane, respectively (p = 0.07, Mann-Whitney U-test). Unacceptable responses to the placement (3 or more coughs, vigorous or persistent [> 30 sec] movements) occurred in 23% and 17% of those who received propofol and sevoflurane, respectively, (p = 0.35. Chi-square test). All these responses were easily suppressed by additional doses of the assigned induction drug. After placement of the COPA, 53% (16/30) of the propofol patients had apnea lasting at least 30 seconds. Notably, the positive airway pressure at which a leak occurred in the mouth (pharyngeal leak pressure) was lower during this propofol-induced apnea than after the return of spontaneous breathing [9 (5 to 20) cmH2O vs. 15 (5 to 20) cmH2O, p < 0.01, Wilcoxon's signed-rank test]. In contrast, at no time were the sevoflurane patients apneic, and their pharyngeal leak pressure immediately following the placement was 12 (10 to 20) cmH2O. CONCLUSIONS: Propofol and sevoflurane are equally effective in facilitating the placement of the COPA. However, propofol often induces apnea, which is complicated by a less effective seal of the airway by the COPA against positive pressures. Because sevoflurane induction allows spontaneous respiration to continue and provides an adequate pharyngeal seal immediately following the placement of the COPA, it may be advantageous when apnea is not desired.

Adult↗
PubMed2003

Propofol versus midazolam/fentanyl for outpatient colonoscopy: administration by nurses supervised by endoscopists.

BACKGROUND & AIMS: Propofol is under evaluation as a sedative for endoscopic procedures. We compared nurse-administered propofol to midazolam plus fentanyl for outpatient colonoscopy. METHODS: One hundred outpatients undergoing colonoscopy were randomized to receive propofol or midazolam plus fentanyl, administered by a registered nurse and supervised only by an endoscopist. Endpoints were patient satisfaction, procedure and recovery times, neuropsychologic function, and complications. RESULTS: The mean dose of propofol administered was 277 mg; mean doses of midazolam and fentanyl were 7.2 mg and 117 microg, respectively. Mean time to sedation was faster with propofol (2.1 vs. 6.1 min; P<0.0001), and depth of sedation was greater (P<0.0001). Patients receiving propofol reached full recovery sooner (16.5 vs. 27.5 min; P=0.0001) and were discharged sooner (36.5 vs. 46.1 min; P=0.01). After recovery, the propofol group scored better on tests reflective of learning, memory, working memory span, and mental speed. Six minor complications occurred in the propofol group: 4 episodes of hypotension, 1 episode of bradycardia, and 1 rash. Five complications occurred with the use of midazolam and fentanyl: one episode of oxygen desaturation requiring mask ventilation and 4 episodes of hypotension. Patients in the propofol vs. midazolam and fentanyl groups reported similar degrees of overall satisfaction using a 10-cm visual analog scale (9.3 vs. 9.4, P>0.5). CONCLUSIONS: Nurse-administered propofol resulted in several advantages for outpatient colonoscopy compared with midazolam plus fentanyl, but did not improve patient satisfaction.

Adjuvants, Anesthesia↗
PubMed2004

Performance of bispectral index and auditory evoked potential monitors in detecting loss of consciousness during anaesthetic induction with propofol with and without fentanyl.

BACKGROUND AND OBJECTIVE: To investigate and compare the performance of bispectral index (BIS) and auditory evoked response index (AAI) in detecting the transition from consciousness to unconsciousness during anaesthesia induction by propofol, alone and in combination with fentanyl. METHODS: Anaesthesia was induced with either an intravenous infusion of 30 mg kg(-1)h(-1) of propofol plus 2 microg kg(-1) of fentanyl (Group PF, n = 20) or an intravenous infusion of 30 mg kg(-1) h(-1) of propofol plus normal saline (Group P, n = 20). BIS, AAI and the doses of propofol administered were recorded at the end-point of unresponsiveness to verbal commands. The propofol plasma concentration was also measured. RESULTS: The propofol dose and plasma propofol concentration required to achieve loss of consciousness were significantly lower in patients pretreated with fentanyl (P < 0.001). The mean BIS value at loss of consciousness was significantly different between the two groups (74.10 in Group PF vs. 60.80 in Group P) (P < 0.001). However, no difference in the AAI was seen between the two groups at loss of consciousness (32.90 in Group PF vs. 31.80 in Group P) (P > 0.05). In both groups, the regression analysis values (r-values) between BIS and plasma propofol concentrations at the onset of unconsciousness were higher than those between AAI and propofol concentrations (0.553 vs. 0.180 in Group P; 0.432 vs. 0.308 in Group PF). CONCLUSIONS: These results show that a fentanyl bolus is effective in augmenting the hypnotic effect of propofol during anaesthesia induction. AAI appears to be able to measure the transition from consciousness to unconsciousness at similar values, regardless of whether or not fentanyl pretreatment is used whereas the BIS values were not independent of fentanyl pretreatment. This suggests that AAI may be a better indicator of conscious status during propofol/fentanyl anaesthesia, where it appears to be independent of the anaesthesia regimen.

Adolescent↗
PubMed2005

Effects of propofol on N-methyl-D-aspartate receptor-mediated calcium increase in cultured rat cerebrocortical neurons.

BACKGROUND AND OBJECTIVE: The intravenous anaesthetic propofol has been reported to exert neuroprotective actions by several mechanisms. This study has been designed to investigate the effects of propofol on intracellular calcium increase in cultured cerebrocortical neurons after exposure to pathological concentrations of N-methyl-D-aspartate (NMDA) mediated by potential direct interactions of propofol with NMDA receptors. METHODS: The effects of propofol (0.1-100 micromol) on intracellular calcium increase induced by 300 micromol NMDA (180 s) were measured in cultured cerebrocortical neurons using the calcium-sensitive fluorochrome calcium green-5N-acetoxymethylester with confocal laser scanning microscopy. RESULTS: The intraneuronal calcium increase after exposure to 300 micromol NMDA depended on extracellular calcium concentration. Propofol reduced the increase of NMDA receptor-induced intraneuronal calcium concentration dependently with a threshold concentration for a significant effect of 10 micromol. The overall effect was small, since even high concentrations of propofol (100 micromol) diminished intraneuronal calcium rise by only 50%. CONCLUSIONS: The threshold concentration for significant effects of propofol on the NMDA-induced increase of intraneuronal calcium turned out to be in the upper limit of propofol concentrations that are considered to be clinically relevant. However, in the presence of high propofol concentrations, inhibition of NMDA receptor-mediated calcium increase might contribute to neuroprotective effects observed with propofol.

Anesthetics, Intravenous↗
PubMed2004

Facilitated assessment of unconsciousness from morphologic changes in the bilateral posterior tibial nerve cortical somatosensory evoked potential under total intravenous propofol anesthesia during spine surgery.

OBJECTIVE: To describe a unique morphologic feature of the bilateral posterior tibial nerve cortical somatosensory evoked potential, the S-wave, which varies systematically with propofol infusion rate and which appears to be useful in guiding adequate propofol concentration levels during spine surgery. METHODS: Two illustrative cases were selected from a pool of 15,000 pediatric and adult patients (ages 8-85 years) who were undergoing corrective spine surgery in operating rooms of university and community hospitals. Anesthesia was maintained with a continuous intravenous infusion of propofol (125-225 microg/kg/min) along with intermittent boluses of narcotic and midazolam (1.0-2.0 mg) as needed. Characteristic metamorphosis of the bilateral posterior tibial nerve cortical somatosensory evoked potential, highlighted by the emergence of an additional middle-latency component labeled the S-wave, served as a neurophysiological marker of "light" propofol anesthesia prompting elevation of propofol infusion rate or bolus injection. RESULTS: The S-wave was routinely abolished with increased propofol infusion rate or bolus injection. In all instances increased propofol concentration levels produced a characteristic morphologic change in the posterior tibial nerve cortical somatosensory evoked potential consistent with a return to adequate anesthetic depth. Selected cases presented herein compare the S-wave technique to BIS and illustrate the usefulness of the S-wave in identifying inadequate depth of propofol anesthesia. CONCLUSIONS: The bilateral posterior tibial nerve cortical somatosensory evoked potential changes its morphology in predictable fashion with decreased depth of propofol anesthesia, allowing for anticipation of imminent anesthetic "lightening." It serves as a useful cross-check to Bispectral Index (BIS) or other "level of consciousness" EEG-based algorithms for monitoring depth of propofol anesthesia during prolonged corrective spine surgery.

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