Propofol versus midazolam for monitored sedation: a comparison of intraoperative and recovery parameters

Immediate effects of propofol on mood: a randomized comparison of two doses in a cohort with depression

RATIONALE

The intravenous anesthetic propofol is known to induce positive mood effects during routine clinical use, suggesting it might be repurposed as an antidepressant, but also raising concerns about abuse potential. How propofol's acute effects vary by dose and with repeated infusions is unknown.

OBJECTIVES

This exploratory analysis aimed to (1) compare the immediate mood effects of propofol administered at two different doses, (2) describe how those mood effects change with repeated infusions, and (3) evaluate whether acute mood improvement predicts later antidepressant response.

METHODS

Twenty-four adults with moderate-to-severe treatment-resistant depression were randomized into two dosing groups. Six low- or high-dose propofol infusions were administered under blinded conditions over a two-week period. Self-reported mood states were recorded before and after each infusion using the Positive and Negative Affect Schedule (PANAS-X). Abuse potential was evaluated with the Drug Effects Questionnaire (DEQ-5).

RESULTS

At the first infusion, propofol induced acute improvements in PANAS-X Sadness, Fear, Joviality, and Serenity scales (p < 0.002), independent of dose. Over the series of six infusions, acute changes in Sadness, Fear, and Joviality, but not Serenity, diminished with infusion number (p < 0.002). The DEQ-5 "want more" rating decreased across infusions (p = 0.002). Changes in PANAS-X scales with the first infusion did not predict later improvement in depression severity (p > 0.05).

CONCLUSION

Cumulative changes in mood states observed with repeated infusions suggest that propofol engages adaptive mechanisms in mood circuitry. Subjective responses with repeated infusions do not indicate increasing potential for abuse in this patient population.

The Effect of Propofol on a Forced Swim Test in Mice at 24 Hours

Background

There are few rapidly acting treatments for acute suicidality or treatment-resistant depression. Propofol (2,6-diisopropylphenol) is an intravenous anesthetic agent used in outpatient settings. It is a gamma-aminobutyric acid type A agonist and has affinity at the N-methyl-D-aspartate receptor. Elevation in mood and sociality in humans has been observed following propofol-induced anesthesia. Other authors reported an open-label study of repeated dosing of propofol in treatment-resistant depression in which several patients experienced sustained improvement. Recently, we reported that in a rodent model of despair, a forced swim test, 45 minutes after administration of 50 mg/kg propofol, immobility time was significantly reduced.

Objective

The objective of the experiment was to determine whether the antidepressant-like effects of a single dose of propofol in mice are sustained for 24 hours.

Methods

The time spent immobile during a forced swim test 24 hours after intraperitoneal administration of a single dose of propofol 50 mg/kg or 0.9% saline was evaluated in 24 adult male mice (C57/BL6). Immobility time was quantified and evaluated with a custom video analysis software program.

Results

Propofol-treated mice were immobile for a mean (SEM) time of 115 (13) seconds, whereas saline-treated mice were immobile for a mean (SEM) time of 94 (14) seconds. A 2-tailed unpaired t test found no significant difference between the treatment groups (t = 1.07, df = 22; P = 0.30).

Conclusions

Twenty-four hours after intraperitoneal administration, the effect of propofol on immobility time was not statistically significantly different from vehicle. However, given our previous report of at least a short-term benefit of propofol on struggling time in the forced swim time and an encouraging pilot study in humans with treatment-resistant depression, further evaluation of propofol's antidepressant potential may be warranted.

Clinical Patterns of Continuous and Intermittent Palliative Sedation in Patients With Terminal Cancer: A Descriptive, Observational Study

CONTEXT

Limited information is available regarding the detailed clinical patterns of palliative sedation (PS), that is, the symptom control rate, salvage medication, and the effectiveness of intermittent PS (IPS) versus continuous PS (CPS).

OBJECTIVES

The primary aim was to investigate clinical outcomes of PS in a real clinical setting.

METHODS

Clinical information was prospectively collected for patients who were treated according to a prescribed protocol and assessment tools in a hospice unit affiliated with a tertiary cancer center between September 2015 and March 2017. Data were analyzed retrospectively. Midazolam was used as the first medication for PS, and propofol and phenobarbital were subsequently used as salvage medications. Indications of PS, the depth of sedation, the quality of sleep, and the level of consciousness were assessed.

RESULTS

A total of 306 patients were enrolled, 89 of whom (29.1%) received PS. No difference in survival time was found between patients with and without PS (median survival, 34.0 vs 25.0 days, P = 0.109). Delirium was the most common indication of PS. The symptoms of 73 (82.0%) of 89 patients with PS were relieved with midazolam. Twelve (75.0%) of 16 midazolam-failure patients responded to propofol, five of whom (31%) exhibited respiratory depression. Of the 89 patients receiving PS, 61 (68.5%) received IPS and 28 patients (31.5%) received CPS. The median survival times from PS initiation to death were six days in the IPS group and one day in the CPS group (P < 0.001). Interestingly, consciousness levels were significantly improved after IPS in the delirium group compared with those in the other group (41.7% vs 16.7%, P = 0.002).

CONCLUSION

The refractory symptoms of end-of-life patients with cancer can ultimately be relieved with various medications for PS. IPS may improve the consciousness level of patients with delirium.

Muscle power during intravenous sedation

Intravenous sedation is effective to reduce fear and anxiety in dental treatment. It also has been used for behavior modification technique in dental patients with special needs. Midazolam and propofol are commonly used for intravenous sedation. Although there have been many researches on the effects of midazolam and propofol on vital function and the recovery profile, little is known about muscle power. This review discusses the effects of intravenous sedation using midazolam and propofol on both grip strength and bite force. During light propofol sedation, grip strength increases slightly and bite force increases in a dose-dependent manner. Grip strength decreases while bite force increases during light midazolam sedation, and also during light sedation using a combination of midazolam and propofol. Flumazenil did not antagonise the increase in bite force by midazolam. These results may suggest following possibilities; (1) Activation of peripheral benzodiazepine receptors located within the temporomandibular joint region and masticatory muscles may be the cause of increasing bite force. (2) Propofol limited the long-latency exteroceptive suppression (ES2) period during jaw-opening reflex. Thus, control of masticatory muscle contraction, which is thought to have a negative feedback effect on excessive bite force, may be depressed by propofol.

Comparison of the Effect of Electrical Stimulations on the Chin Skin on Autonomic Nervous Activities During Propofol Sedation With or Without Midazolam

PURPOSE

The aim of this study was to compare the effect of electrical stimulations on the chin skin on autonomic nervous activities evaluated by use of power spectrum analysis of heart rate (HR) variability during intravenous sedation using propofol with or without midazolam.

MATERIALS AND METHODS

Thirty-eight healthy adult male volunteers underwent intravenous sedation with midazolam and propofol (group MP) and with propofol alone (group P) in a randomized crossover manner. In group MP, the participants received midazolam (0.04 mg/kg) and a target-controlled infusion of propofol with a predicted blood concentration of 1.0 μg/mL. In group P, the predicted blood concentration of propofol was maintained at 1.5 μg/mL. The observed variables were bispectral index value, systolic blood pressure, HR, high-frequency component (HF), low-frequency component (LF), and LF/HF ratio. Measurements were conducted over 100-second periods and carried out before, during, and after emergence from sedation by administering 0.2 mg of flumazenil. The paired t test, Wilcoxon t test, repeated-measures analysis of variance, and Friedman χ(2) r test were used for statistical analyses.

RESULTS

The mean age and body weight of the participants were 24.6 ± 2.8 years and 67.0 ± 7.9 kg, respectively. Bispectral index values, systolic blood pressure, and HR showed similar changes in both groups. The LF/HF ratio in group MP during sedation was lower than that before sedation; it also was lower than that in group P during sedation.

CONCLUSIONS

Intravenous sedation with a combination of midazolam and propofol inhibited sympathetic nervous activation induced by electrical stimulations to a greater extent than that with propofol alone.

Comparison of Clinical Effects of Dexketoprofen and Paracetamol Used for Analgesia in Endoscopic Retrograde Cholangiopancreatography

OBJECTIVE

This study aimed to compare 50 mg dexketoprofen vs. 1 g paracetamol that were parenterally administered before endoscopic retrograde cholangiopancreatography (ERCP) under sedoanalgesia with comparable anaesthesia depth regarding haemodynamic, pain, narcotic analgesic requirement, recovery and post-procedural cognitive functions.

METHODS

Overall, 80 ASA I-III patients aged 18-75 years who were undergoing scheduled ERCP were randomly assigned into three groups. In all patients, the mini-mental test (MMT) was conducted before the procedure. No drug was administered to controls (Group C; n=26); patients were transferred to ERCP unite 30 min after parenteral dexketoprofen (50 mg) in group D (n=27) and paracetamol (1 g) in group P (n=27). The standard monitoring was applied. After intravenously administering loading doses of midazolam (0.02 mgkg) and propofol (1 mg kg(-1)), propofol infusion was administered at a dose of 2-4 mg kg(-1) h(-1) to maintain a bispectral index value of 50-70. Fentanyl (0.05 μg kg(-1)) was intravenously administered when patients experienced pain. Haemodynamic effects, additional analgesic requirement, adverse effects during procedure, time to reach Aldrete score of 9 and satisfaction of an endoscopist and patient were recorded. MMT was repeated 3 h after completing the procedure.

RESULTS

Fentanyl requirement during the procedure was significantly low in group D (p<0.05). Apnoea during the procedure and nausea after the procedure were least common in group D while significantly lower than group C (p<0.05). There was no significant difference with respect to MMT scores and endoscopist's satisfaction, while patient satisfaction was greater in group P.

CONCLUSION

Parenterally administered dexketoprofen provided better haemodynamic effect and pain control, thereby decreasing incidence of adverse events by reducing the requirement for narcotic analgesics.

Polymorphism rs4263535 in GABRA1 intron 4 was related to deeper sedation by intravenous midazolam

OBJECTIVE

To evaluate whether polymorphisms in the gamma-aminobutyric acid A receptor α1 subunit (GABRA1) gene influence sleep induction time, bispectral index score (BIS) during sleep induction and the total dose of midazolam required to reach a Ramsay Sedation Assessment Scale (RSAS) score of 4.

METHODS

Patients scheduled for elective orthopaedic surgery were enrolled. All patients received initial doses of 0.02 mg/kg intravenous midazolam. If the RSAS score did not reach 4, an additional 1-mg dose of midazolam was administered. Results were compared among groups of patients with five single-nucleotide polymorphisms (SNPs) in GABRA1: rs4263535, rs980791, rs6556562, rs998754 and rs2279020.

RESULTS

A total of 104 patients were evaluated. Polymorphism rs4263535 was associated with the lowest BIS during sedation induction. Multinomial logistic regression analysis demonstrated that polymorphism rs4263535 was significantly associated with the total dose of midazolam required for sedation induction.

CONCLUSIONS

Polymorphism rs4263535 in GABRA1 intron 4 was associated with deeper sedation by intravenous midazolam. Patients with the A/A rs4263535 genotype required a smaller dose of midazolam.

The combined effects of midazolam and propofol sedation on muscle power

We performed a randomised, crossover study to investigate the effects of intravenous sedation on grip strength and bite force. Twenty male volunteers received a bolus intravenous injection of midazolam (0.02 mg.kg(-1)) together with a 30-min propofol infusion designed to achieve an effect-site concentration of 1.0 μg.ml(-1). Observed variables included bispectral index, observer's assessment of alertness/sedation, correct answer rate of Stroop colour-word test, grip strength and bite force. Grip strength decreased from a median (IQR [range]) of 483 (443-517 [380-586]) N to 358 (280-405 [108-580]) N (p < 0.001) during sedation and recovered following flumazenil administration, while bite force increased from 818 (593-1026 [405-1406]) N to 1377 (1243-1585 [836-2357]) N (p < 0.001) during sedation. Although bite force gradually returned to baseline following flumazenil administration, it remained increased throughout the experimental period. We conclude that bite force increased during intravenous sedation and that this may have clinical implications.

Efficacy and cost analysis of transrectal ultrasound-guided prostate biopsy under monitored anesthesia

Sedation may result in reduction in pain during transrectal ultrasound (TRUS)-guided prostate biopsies. We aimed to evaluate the efficacy and safety of a combination of propofol and remifentanil infusion during TRUS-guided prostate biopsy and the related increases in health care costs. From January to September 2010, 100 men undergoing a transrectal prostate biopsy were randomized into two groups. In Group 1, 50 patients received a combined infusion of propofol and remifentanil; in Group 2, 50 patients received lidocaine jelly. After TRUS-guided biopsies were performed, pain and patient satisfaction were evaluated by a 10-point visual analog scale (VAS), and a cost-related patient satisfaction questionnaire was completed by all patients. Patients were also asked whether they would be willing to undergo repeat biopsy by the same method. Patients in Group 1 showed a significantly lower VAS score than those in Group 2 (mean VAS score: 0.9±1.1 versus 6.3±2.5; P<0.001). In addition, the patient satisfaction scale was significantly higher in Group 1 (P=0.002). Although the overall cost was significantly higher in Group 1 (P=0.006), patient satisfaction scales considering cost were also higher in this group (P=0.009). A combination of propofol and remifentanil is a safe and effective way to decrease patient pain and increase patient satisfaction during TRUS-guided prostate biopsy. Although the costs were higher in the group that received sedation, as expected, the patients exhibited heightened satisfaction and willingness to repeat biopsies by the same method.

Safety evaluation of fospropofol for sedation during minor surgical procedures

STUDY OBJECTIVE

To evaluate the safety of intravenous (IV) fospropofol when used to provide minimal to moderate sedation in patients undergoing minor surgical procedures.

DESIGN

Phase 3, open-label, single-arm study.

SETTING

Multi-center.

PATIENTS

123 ASA physical status I, II, III, and IV patients, aged>or=18 years.

INTERVENTIONS

Patients were pretreated with fentanyl 50 microg before receiving an initial dose of IV fospropofol 6.5 mg/kg. Patients could receive up to 5 supplemental doses of fospropofol 1.63 mg/kg to reach a Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score<or=4 to allow the start of the procedure and to maintain adequate sedation levels during the procedure.

MEASUREMENTS

Study endpoints included measures of sedation depth, requirement for supplemental sedative doses, use of alternative sedatives, and the frequency and nature of treatment-emergent and sedative-related adverse events.

MAIN RESULTS

A mean of 2.4 supplemental doses of fospropofol was administered, and in 60% of patients, two or fewer supplemental doses of fospropofol were sufficient to initiate and complete the procedure. Alternative sedative medication was administered in 6 of 123 patients (4.9%). Mean (SD) MOAA/S score during the procedure was 3.8 (0.5). Sixty-one percent (61%) of patients had a MOAA/S score of 5 (fully alert) within two minutes after the end of the procedure. Few patients (7 of 123; 5.7%) had MOAA/S scores of 0 to 1 (deep sedation) during the procedure, and all 7 were either ASA physical status I (n=1) or II (n=6). The most common treatment-related adverse events (TRAEs) were self-limited: paresthesias (62.6%) and pruritus (27.6%). Five patients experienced sedation-related adverse events, including hypotension (n=4), bradycardia (concurrently with hypotension and managed with atropine; n=1), or hypoxemia (less than one min and managed with chin lift and verbal stimulation; n=1). Twenty patients with previous or existing hepatic disease (ranging from minimal to severe) and 5 patients with severe renal impairment had adverse events similar to the overall population. No deaths were reported, and no patient discontinued the study due to adverse events.

CONCLUSION

An initial dose of IV fospropofol 6.5 mg/kg with supplemental doses was safe and well-tolerated as moderate sedation for use in minor surgical procedures.

Sedative effects of propofol in horses

OBJECTIVE

We hypothesized that propofol can produce rapidly-reversible, dose-dependent standing sedation in horses.

STUDY DESIGN

Prospective randomized, blinded, experimental trial.

ANIMALS

Twelve healthy horses aged 12 +/- 6 years (mean +/- SD), weighing 565 +/- 20 kg, and with an equal distribution of mares and geldings.

METHODS

Propofol was administered as an intravenous bolus at one of three randomized doses (0.20, 0.35 and 0.50 mg kg(-1)). Cardiovascular and behavioral measurements were made by a single investigator, who was blinded to treatment dose, at 3 minute intervals until subjective behavior scores returned to pre-sedation baseline values. Continuous data were analyzed over time using repeated-measures anova and noncontinuous data were analyzed using Friedman tests.

RESULTS

There were no significant propofol dose or temporal effects on heart rate, respiratory rate, vertical head height, or jugular venous blood gases (pH(v), P(v)O(2), P(v)CO(2)). The 0.35 mg kg(-1) dose caused mild sedation lasting up to 6 minutes. The 0.50 mg kg(-1) dose increased sedation depth and duration, but with increased ataxia and apparent muscle weakness.

CONCLUSIONS AND CLINICAL RELEVANCE

Intravenous 0.35 mg kg(-1) propofol provided brief, mild sedation in horses. Caution is warranted at higher doses due to increased risk of ataxia.

Analgo-sedation of patients with burns outside the operating room

Following the initial resuscitation of burn patients, the pain experienced may be divided into a 'background' pain and a 'breakthrough' pain associated with painful procedures. While background pain may be treated with intravenous opioids via continuous infusion or patient-controlled analgesia (PCA) and/or less potent oral opioids, breakthrough pain may be treated with a variety of interventions. The aim is to reduce patient anxiety, improve analgesia and ensure immobilization when required. Untreated pain and improper sedation may result in psychological distress such as post-traumatic stress disorder, major depression or delirium. This review summarizes recent developments and current techniques in sedation and analgesia in non-intubated adult burn patients during painful procedures performed outside the operating room (e.g. staple removal, wound-dressing, bathing). Current techniques of sedation and analgesia include different approaches, from a slight increase in background pain therapy (e.g. morphine PCA) to PCA with rapid-onset opioids, to multimodal drug combinations, nitrous oxide, regional blocks, or non-pharmacological approaches such as hypnosis and virtual reality. The most reliable way to administer drugs is intravenously. Fast-acting opioids can be combined with ketamine, propofol or benzodiazepines. Adjuvant drugs such as clonidine or NSAIDs and paracetamol (acetaminophen) have also been used. Patients receiving ketamine will usually maintain spontaneous breathing. This is an important feature in patients who are continuously turned during wound dressing procedures and where analgo-sedation is often performed by practitioners who are not specialists in anaesthesiology. Drugs are given in small boluses or by patient-controlled sedation, which is titrated to effect, according to sedation and pain scales. Patient-controlled infusion with propofol has also been used. However, we must bear in mind that burn patients often show an altered pharmacokinetic and pharmacodynamic response to drugs as a result of altered haemodynamics, protein binding and/or increased extracellular fluid volume, and possible changes in glomerular filtration. Because sedation and analgesia can range from minimal sedation (anxiolysis) to general anaesthesia, sedative and analgesic agents should always be administered by designated trained practitioners and not by the person performing the procedure. At least one individual who is capable of establishing a patent airway and positive pressure ventilation, as well as someone who can call for additional assistance, should always be present whenever analgo-sedation is administered. Oxygen should be routinely delivered during sedation. Blood pressure and continuous ECG monitoring should be carried out whenever possible, even if a patient is undergoing bathing or other procedures that may limit monitoring of vital pulse-oximetry parameters.

Effect of flumazenil on disturbance of equilibrium function induced by midazolam

Benzodiazepines in intravenous sedation are useful, owing to their outstanding amnesic effect when used for oral surgery as well as dental treatments on patients with intellectual disability or dental phobia. However, compared with propofol, the effect of benzodiazepine lasts longer and may impede discharge, especially when it is administered orally because of fear of injections. Although flumazenil antagonizes the effects of benzodiazepine quickly, its effect on the equilibrium function (EF) has never been tested. Since EF is more objective than other tests, the purpose of this study is to assess the sedation level and EF using a computerized static posturographic platform. The collection of control values was followed by the injection of 0.075 mg/kg of midazolam. Thirty minutes later, 0.5 mg or 1.0 mg of flumazenil was administered, and the sedation level and EF were measured until 150 minutes after flumazenil administration. Flumazenil antagonized sedation, and there was no apparent resedation; however, it failed to antagonize the disturbance in EF. This finding may be due to differences in the difficulty of assessing the sedation level and performing the EF test, and a greater amount of flumazenil may effectively antagonize the disturbance in EF.

Propofol infusion for sedation during spinal anesthesia

PURPOSE

The dose and time course of propofol infusion required to induce rapid sedation without oversedation during spinal anesthesia were investigated.

METHODS

Forty patients scheduled for spinal and epidural anesthesia were studied. After premedication with intramuscular midazolam 0.04 mg.kg(-1), an epidural catheter was inserted, followed by spinal anersthesia at L4-L5 with 0.5% hyperbaric tetracaine with epinephrine. The infusion of propofol was started with 10 mg.kg(-1).h(-1) and was decreased to 5 mg.kg(-1).h(-1) at spontaneous eye closure. According to the increase or decrease of the sedation level, the infusion does was decreased or increased to half or twice the initial dose, respectively, to keep the Observer's Assessment of Alertness Sedation (OAAS) score at 3 or 4.

RESULTS

Eye closure was observed at 1.0 +/- 0.4 min after the start of insusion. The maintenance insusion dose to keep the OAAS score at 3 or 4 was about 2.5 mg.kg(-1).h(-1).

CONCLUSION

Propofol infusion, starting with 10 mg.kg(-1).h(-1), decreasing to 5 mg.kg(-1).h(-1) after 1 minute, and then decreasing to 2.5 mg.kg(-1).h(-1) after another min induced rapid onset of sedation and kept the OAAS score at 3 or 4 during spinal anesthesia.

The Effect of the Assignment of a Pre-Sedation Target Level on Procedural Sedation Using Propofol

The goal of this study was to determine if there is a difference in the achieved depth of sedation, the rate of respiratory depression, procedural difficulty, or patient perceived pain or recall between patients randomized to a pre-procedural target sedation level of moderate or deep procedural sedation using propofol during the reduction of fractures and dislocations in the Emergency Department (ED). This was a randomized, prospective study of adults undergoing procedural sedation (PS) with propofol for fracture or dislocation reduction in the ED between July 2003 and March 2004. Patients were randomized to a target sedation level of moderate or deep, using American Society of Anesthesiologists' definitions. Doses, vital signs, nasal end tidal CO(2) (ETCO(2)), pulse oximetry, and bispectral EEG analysis (BIS) scores were recorded. Respiratory depression was defined as a change in ETCO(2) >10, an oxygen saturation of <90% at any time, or an absent ETCO(2) waveform at any time. After the procedure, patients were asked if they perceived any pain or had any recall of the procedure. Physicians were asked to rate the difficulty of completing the reduction using a 100-mm visual analog scale (VAS). Respiratory depression rates were compared with chi-square tests, BIS and VAS scores were compared with t tests. Seventy-five patients were enrolled, 39 randomized to the target of moderate PS and 36 to the target of deep PS. No significant complications were noted. There were 25/36 (69%) of the patients assigned to the deep sedation target group who actually achieved a deep level of sedation and 21/39 (54%) of the patients assigned to the moderate sedation target group who actually achieved a moderate level of sedation (p = 0.40). Respiratory depression was seen in 19/39 (49%) patients with the moderate PS target and 18/36 (50%) with the deep PS target (p = 0.91). The mean minimum recorded BIS score was 67.7 (95% confidence interval [CI] 62.2-73.3) for the moderate PS target group and 59.2 (95% CI 55.1-64.2) for the deep PS target group (p = 0.03). There were 12/39 (31%) in the moderate PS target group and 4/36 (11%) in the deep PS target group who reported pain with or recall of the procedure (p = 0.04). The mean physician VAS for procedural difficulty was 34.0 (95% CI 23.7-44.3) for the moderate PS group and 28.8 (95% CI 18.4-39.2) for the deep PS group (p = 0.46). In this study, the assignment of a pre-procedural target sedation level of moderate or deep PS did not influence the level of sedation achieved, the rate of respiratory depression, the occurrence of complications, the time to return of baseline mental status, or the success of the procedure. It does not seem that the assignment of a pre-procedural target sedation level is an effective means of changing the outcome of ED PS.

Low-dose propofol infusion for sedation during local anesthesia

The safety and efficacy of lose-dose propofol for sedation were investigated on 90 consenting patients who had undergone surgical procedures with local anesthesia. After being premedicated with intravenous midazolam 0.05 mg.kg(-1), all patients were randomly divided into two groups and received intravenously either a loading dose of propofol 0.8 mg.kg(-1) followed by a continuous infusion of propofol 30 microg.kg(-1)min(-1) (propofol group) or an equivalent volume of saline (placebo group) during operation. Study groups were compared with respect to the level of sedation, hemodynamic variables, oxygen saturation, and the incidence of intraoperative side effects. In addition, the discharge time and the satisfaction of both patients and surgeons with this sedative technique were assessed. Propofol reduced patients' discomfort and lowered their arterial pressure and heart rate during the infiltration of local anesthetics. It also promoted an adequate level of sedation without clinically significant oxygen desaturation in the intraoperative period. Surgeons and patients in the propofol group showed a higher level of satisfaction than those in the placebo group. There was no significant difference between the two groups with regard to the incidence of adverse effects and the discharge time. In conclusion, it was found that the use of low-dose propofol infusion was a safe and effective sedative technique for local anesthesia.

When midazolam fails

Significant distress is experienced by patients, families, and caregivers when a symptom or disorder, such as an agitated delirium, becomes an intractable, or a catastrophic event, such as irreversible stridor. When palliative sedation is indicated for these patients, midazolam is usually the preferred drug. In some cases, however, midazolam fails to provide adequate sedation. Two cases are presented to illustrate this phenomenon and explore the possible mechanisms underlying this lack of response. These mechanisms appear to be multifaceted. The heterogeneity of the GABA(A) receptor complex and the alterations that this complex can undergo functionally can explain, to some degree, the diversity of the physiological and pharmacological outcomes. Other factors responsible for the diversity in response may include concomitant medications, age, concurrent disease, overall health status, alcohol use, liver disease, renal disease, smoking and hormonal status. Evidence-based guidelines on alternative treatment options should midazolam fail are required. In the interim, a lower threshold for adding an alternative drug, such as phenobarbital, or substituting midazolam with another drug, such as propofol, should be considered in these circumstances.

Changes in respiratory pattern and arterial blood gases during sedation with propofol or midazolam in spinal anesthesia

STUDY OBJECTIVE

To investigate changes in respiratory pattern and arterial blood gases during sedation with propofol or midazolam in spinal anesthesia.

DESIGN

Randomized, placebo-controlled study.

SETTING

Operating room of a university-affiliated hospital.

PATIENTS

40 ASA physical status I and II patients who required spinal anesthesia.

INTERVENTIONS

Spinal anesthesia with tetracaine and subsequent sedation with propofol (n = 15), midazolam (n = 15), or placebo (n = 10) was performed.

MEASUREMENTS

Respiratory pattern [rib cage contribution to the tidal volume (%RC) and phase shift between rib cage and abdominal movements (PSrc-ab)] with a respiratory inductive plethysmograph (Respigraph) and arterial blood gas analysis (pH, pO2, and pCO2) were recorded.

MAIN RESULTS

Spinal anesthesia per se increased %RC by 35% without changing PSrc-ab values (1.00). Sedation with propofol and midazolam decreased %RC by 60% and by 40%, respectively. PSrc-ab increased in both groups following sedation, and the increase in this parameter was higher in the propofol group (1.12) than in the midazolam group (1.04). In the placebo group, %RC decreased by 20% without any change in PSrc-ab. The decrease in pO2 was more significant in the propofol group (65.1 mmHg) than in the midazolam (74.2 mmHg) and placebo (83.1 mmHg) groups.

CONCLUSION

Significant decreases in %RC and pO2 during propofol sedation seem to depend on paradoxical respiration due, in part, to upper airway obstruction; therefore, attention should be directed to the respiratory pattern during sedation, especially with propofol.

Propofol anesthesia for outpatient oral and maxillofacial surgery

Propofol is a sedative-hypnotic intravenous anesthetic agent that has gained wide use in outpatient oral and maxillofacial surgery since its clinical introduction in 1985. Propofol has several therapeutic advantages that make it an excellent choice for use in all phases of general anesthesia and conscious sedation. It is associated with minimal side effects, a controllable anesthetic state, and rapid recovery. This review of propofol discusses its pharmacologic character, administration, and side effects and presents anesthetic drug interaction information and comparisons.

The cost-effectiveness of methohexital versus propofol for sedation during monitored anesthesia care

We designed this study to test the hypothesis that methohexital is a cost-effective alternative to propofol for sedation during local anesthesia. Sixty consenting women undergoing breast biopsy procedures under local anesthesia were randomly assigned to receive an infusion of either propofol (50 microg x kg(-1) x min(-1)) or methohexital (40 microg x kg(-1) x min(-1)). The sedative infusion rate was titrated to maintain an observer's assessment of alertness/sedation (OAA/S) score of 3 (with 1 = awake/alert to 5 = asleep). Fentanyl 25 microg i.v. was administered as a "rescue" analgesic during the operation. We assessed the level of sedation (OAA/S score), vital signs, time to achieve an OAA/S score of 3 at the onset and a score of 1 after discontinuing the infusion, discharge times, perioperative side effects, and patient satisfaction. The direct cost of methohexital was lower than that of propofol, based on the milligram dosage infused during the operation. The sedative onset (to achieve an OAA/S score of 3) and the recovery (to return to an OAA/S score of 1) times, as well as discharge times, did not differ between the two groups. Patients receiving methohexital had a significantly lower incidence of pain on initial injection compared with those receiving propofol (10% vs 23%). Because the use of methohexital (29.4 +/- 2.7 microg x kg(-1) x min(-1)) for sedation during breast biopsy procedures has a similar efficacy and recovery profile to that of propofol (36.8 +/- 15.9 microg x kg(-1) x min(-1)) and is less costly based on the amount infused, it seems to be a cost-effective alternative to propofol for sedation during local anesthesia. However, when the cost of the drug infused and drug wasted was calculated, there was no difference in the overall drug cost.

IMPLICATIONS

When administered to maintain a stable level of sedation during local anesthesia, methohexital is an acceptable alternative to propofol. However, the overall drug costs were similar with the two drugs.

What is new in monitored anesthesia care?

The use of monitored anesthesia care (MAC) techniques is increasing in popularity because recovery profiles seem to be improved compared with general and regional anesthesia. This article describes the conceptual basis for MAC and reviews the current MAC practices.

Efficacy and safety of a new protocol for continuous infusion of midazolam and fentanyl and its effects on patient distress during electrophysiological studies

Electrophysiological studies are often distressing for patients. We devised a regime of continuous infusion of midazolam and fentanyl during electrophysiological studies without the presence of a specialist anaesthetist. The effects on key hemodynamic and respiratory variables and level of sedation were evaluated in detail in the first 775 patients. The safety of this practice was evaluated in 1,344 consecutive patients. Doses were calculated according to patients' weight and age. A mean total dose of 26 mg of midazolam and 115 mcg of fentanyl were infused. Satisfactory sedation was achieved in 97% of patients. The mean duration of procedure was 188 +/- 90 minutes. Complete amnesia of the procedure was obtained in 87% of patients. Sedation caused clinically insignificant changes in respiratory rate, oxygen saturation, end-tidal CO2 and blood pressure. There were no major complications related to sedation. Upper airway obstruction, usually minor, occurred in 42% and some restlessness in 20% of sedated patients. The assistance of a specialist anesthetist was required in 0.3% of sedated patients for management of restlessness, hypoventilation, or obstructive sleep apnea. The amount of distress experienced by sedated patients (n = 775) was significantly less compared to a previous series of nonsedated patients (n = 775) undergoing electrophysiological studies (P < 0.001). The degree of distress experienced by patients during electrophysiological studies can be reduced significantly by sedation with intravenous midazolam and fentanyl. Continuous infusion is an efficient, safe, and effective way of administering midazolam and fentanyl.

Impact of anesthesia on the cognitive functioning of the elderly

Exposure to general anesthesia has been suggested as a possible cause of long-term cognitive impairment in elderly subjects. The present study reviews the literature in this field in order to describe postoperative cognitive impairment in elderly populations, to determine to what extent this may be attributed to anesthetic agents, and to consider evidence of a causal relationship between anesthesia and onset of senile dementia. A systematic literature search was conducted using five bibliographic databases (PASCAL, Medline, Excerpta Medica, Psychological Abstracts, and Science Citation Index). Significant cognitive dysfunction was found to be common in elderly persons 1 to 3 days after surgery, but reports of longer-term impairment are inconsistent due to the heterogeneity of the procedures used and populations targeted in such studies. Incidence rates vary widely according to type of surgery, suggesting that factors other than anesthesia explain a significant proportion of the observed variance. Anesthesia appears to be associated with longerterm cognitive disorder and the acceleration of senile dementia, but only in a small number of cases, suggesting the existence of other interacting etiological factors.

Midazolam premedication increases sedation but does not prolong discharge times after brief outpatient general anesthesia for laparoscopic tubal sterilization

Preoperatively administered midazolam may contribute to postoperative sedation and delayed recovery from brief outpatient general anesthesia, particularly in patients who receive significant postoperative opioid analgesics. We evaluated the effects of midazolam premedication (0.04 mg/kg) on postoperative sedation and recovery times after laparoscopic tubal sterilization (Falope rings) in 30 healthy women in a randomized, double-blind, placebo-controlled study. Patients received midazolam or saline-placebo intravenously 10 min before anesthesia. General anesthesia was induced with fentanyl, propofol, and mivacurium and was maintained with N2O and isoflurane. Sedation was quantified before and after premedication and 15, 30, and 60 min after emergence from anesthesia, using the digit-symbol substitution (DSST) and Trieger dot (TDT) tests. Management of postoperative pain and nausea and discharge criteria were standardized. Groups were similar with respect to age, weight, and duration of surgery and anesthesia. Midazolam was associated with impairment of performance on the TDT and DSST after premedication administration and 15 (TDT and DSST) and 30 (DSST) min after postanesthesia care unit (PACU) arrival. There were no differences in PACU time and time to discharge-readiness. In conclusion, midazolam premedication augments postoperative sedation in this population but does not prolong recovery times.

Propofol sedation during awake craniotomy for seizures: patient-controlled administration versus neurolept analgesia

This prospective study evaluated the safety and efficacy of patient-controlled sedation (PCS) using propofol during awake seizure surgery performed under bupivacaine scalp blocks. Thirty-seven patients were randomized to receive either propofol PCS combined with a basal infusion of propofol (n = 20) or neurolept analgesia using an initial bolus dose of fentanyl and droperidol followed by a fentanyl infusion (n = 17). Both groups received supplemental fentanyl and dimenhydrinate for intraoperative pain and nausea, respectively. Comparisons were made between groups for sedation, memory, and cognitive function, patient satisfaction, and incidence of complications. Levels of intraoperative sedation and patient satisfaction were similar between groups. Memory and cognitive function were well preserved in both groups. The incidence of transient episodes of ventilatory rate depression (<8 bpm) was more frequent among the propofol patients (5 vs 0, P = 0.04), particularly after supplemental doses of opioid. Intraoperative seizures were more common among the neurolept patients (7 vs 0, P = 0.002). PCS using propofol represents an effective alternative to neurolept analgesia during awake seizure surgery performed in a monitored care environment.

Effects of sedation with midazolam or propofol on cognition and psychomotor functions

PURPOSE

The study compared the effects of midazolam and propofol on explicit and implicit memory, cognition, and psychomotor function in patients undergoing oral surgical procedures with local anesthesia and conscious sedation.

METHODS

Twenty-eight patients were tested in a randomized, double-blind study. Patients were randomly allocated to one of two groups. One group received a bolus dose of midazolam, 0.1 mg/kg, followed by a continuous infusion of saline. The other group received a bolus dose of propofol, 1.0 mg/ kg, followed by a continuous infusion of propofol, 65 micrograms/kg/min. Subjective rating questionnaires and tapping, memory, and Digit Symbol Substitution tests were administered. Testing was done at baseline, 10 minutes after the drugs were given, 10 minutes after surgery ended and 10 minutes later.

RESULTS

The midazolam and propofol groups did not differ significantly on any demographic variables. Both drugs produced mental and physical sedation, which did not become substantially attenuated during the time studied. Both tranquilization and attitudes or other feelings showed smaller drug effects than mental and physical sedation. Tapping was decreased by both drugs 10 minutes after treatment, but not postsurgery. Performance on the Digit Symbol Substitution test was below baseline levels for both drugs at 10 minutes after treatment, but only for midazolam in the postsurgery assessment; at 10 minutes after treatment, propofol was associated with poorer performance than midazolam. Immediate and delayed explicit recall were impaired by both drugs 10 minutes after treatment. Immediate and delayed recall were lower for midazolam than propofol postsurgery, but only the difference on immediate recall was significant. Implicit memory was spared by both drugs.

CONCLUSIONS

Midazolam and propofol generally produced equivalent impairments, but the duration of the effects of propofol was shorter. Unlike explicit memory, implicit memory resisted impairment.

Propofol versus midazolam for sedation during percutaneous transluminal angioplasty

PURPOSE

To prospectively and randomly compare use of propofol versus midazolam for sedation during percutaneous transluminal angioplasty (PTA).

MATERIALS AND METHODS

Forty patients (27 men, 13 women; mean age 64.4 years +/- 12.2) who underwent PTA of the arteries below the diaphragm were prospectively randomized for sedation with propofol or midazolam. Both drugs were administered after an initial bolus injection by means of continuous infusion to achieve conscious sedation at levels II-III according to the Ramsay classification. Patients and interventionalists were blinded to the applied sedative. Both groups were similar with regard to American Society of Anesthesiology status, heart rate, blood pressure, arterial oxygen pressure (pO2), arterial carbon dioxide pressure (pCO2), arterial oxygen saturation (SpO2), and visual analogue scores for general condition, anxiety, and pain. During PTA, heart rate, blood pressure, and pulse oximetry (tpO2) were monitored continually. Every 30 minutes, an arterial blood gas analysis was performed. Visual analogue scores were obtained before, during, and after intervention.

RESULTS

Decreases in SpO2, pO2, and tpO2 were significantly greater after sedation with midazolam (P < .05; t test). The increase in pCO2 was significantly greater after midazolam (P < .05; t test). No significant difference between the drugs was found with regard to any of the other parameters. Both drugs resulted in sufficient sedation and anxiolysis (P < .01 for both drugs for visual analogue score for anxiety before and during PTA; matched pairs test). Satisfaction of the interventionalist was significantly greater for propofol (P < .05; t test).

CONCLUSION

Propofol causes less respiratory depression than midazolam for equivalent sedation and anxiolysis in patients undergoing PTA.

Propofol in terminal care

In advanced cancer patients close to death, delirium, multifocal myoclonus, and restlessness may occur. Multi-organ failure and related metabolic changes are mostly responsible for these symptoms. A pharmacologic approach to manage the delirium is necessary in the majority of cases. Benzodiazepines, neuroleptics, and barbiturates are the most common drugs used. In the case reported, propofol administered at very low doses provided good control of neuropsychiatric symptoms. After a loading dose of 20 mg, an infusion of 50-70 mg per hr was started. The patient died peacefully after 8 hr of propofol infusion, without requiring opioids. Propofol seems to be a promising drug in treating the terminal agitated state that can be associated with the dying process.

Comparison of propofol administration techniques for sedation during monitored anesthesia care

Sixty-three outpatients undergoing breast biopsy procedures with local anesthesia were randomly assigned to receive propofol by intermittent bolus injections (n = 21), a conventional syringe infusion pump (n = 21), or a target-controlled infusion (TCI) device (n = 21) for intraoperative sedation. In the first two groups, an initial intravenous (IV) bolus of propofol (0.3 mg/kg) was administered and an attempt was made to maintain the sedation level at an Observer's Assessment of Alertness/Sedation (OAA/S) score of 3 or 4 with either intermittent bolus injections of propofol (10 mg) or a variable-rate infusion (25-100 micrograms.kg-1.min-1). In the TCI group, the initial target concentration of propofol was set at 2 micrograms/mL and the target concentration was adjusted between 1 and 4 micrograms/mL in an attempt to maintain an OAA/S score of 3 or 4. Recovery was assessed using clinical criteria, visual analog scales (VAS), and the digit-symbol substitution test (DSST). The overall quality of sedation, operating conditions, and clinical recovery profiles were similar in all three treatment groups. The anesthesiologist had to intervene more frequently in the intermittent bolus injection group than in the two infusion groups. We conclude that the use of an infusion technique may allow the anesthesiologist more time for monitoring the patient by decreasing the number of interventions necessary to administer supplemental doses of the sedative medication during the operation. However, the cost of the IV drug delivery system may become an increasingly important factor in the future.