Propofol Bolus Research Articles

Propofol versus alfentanil to prevent movement responses during uterine curettage

Propofol anaesthesia is frequently associated with movement responses in non-paralysed patients. Opioids decrease the probability of movement during noxious stimulation. Heart rate variability and frontal electromyography (EMG), which are related to subcortical functions, may be more closely related than surface electroencephalography (EEG) to movement responses to noxious stimulation. Eighty-two patients scheduled for uterine dilatation and curettage were randomized to receive at the first intra-operative movement either a supplemental alfentanil bolus, 0.5 mg intravenously, or a supplemental propofol bolus, 0.7 mg/kg intravenously. The incidences of recurring movement during the procedure were compared between the two groups. The associations of a measure of heart rate variability (Anemon index), heart rate, EMG and two EEG variables with movement responses were evaluated. The incidences of recurring movement were 73% and 38% in the alfentanil and propofol groups, respectively [difference, 35%; 95% confidence interval, 9-56%; P= 0.014 between the groups). The Anemon index, heart rate, EMG and surface EEG variables displayed mainly reactive associations with movement responses. During uterine curettage under propofol-alfentanil-nitrous oxide anaesthesia, a propofol bolus of 0.7 mg/kg was more effective in preventing the recurrence of movement responses than an alfentanil bolus of 0.5 mg. Several physiological variables may be used to track significant arousal reactions, but not to predict them.

Impact of depth of propofol anaesthesia on functional residual capacity and ventilation distribution in healthy preschool children

Propofol is commonly used in children undergoing diagnostic interventions under anaesthesia or deep sedation. Because hypoxaemia is the most common cause of critical deterioration during anaesthesia and sedation, improved understanding of the effects of anaesthetics on pulmonary function is essential. The aim of this study was to determine the effect of different levels of propofol anaesthesia on functional residual capacity (FRC) and ventilation distribution. In 20 children without cardiopulmonary disease mean age (SD) 49.75 (13.3) months and mean weight (SD) 17.5 (3.9) kg, anaesthesia was induced by a bolus of i.v. propofol 2 mg kg(-1) followed by an infusion of propofol 120 microg kg(-1) min(-1) (level I). Then, a bolus of propofol 1 mg kg(-1) was given followed by a propofol infusion at 240 microg kg(-1) min(-1) (level II). FRC and lung clearance index (LCI) were calculated at each level of anaesthesia using multibreath analysis. The FRC mean (SD) decreased from 20.7 (3.3) ml kg(-1) at anaesthesia level I to 17.7 (3.9) ml kg(-1) at level II (P < 0.0001). At the same time, mean (SD) LCI increased from 10.4 (1.1) to 11.9 (2.2) (P = 0.0038), whereas bispectral index score values decreased from mean (SD) 57.5 (7.2) to 35.5 (5.9) (P < 0.0001). Propofol elicited a deeper level of anaesthesia that led to a significant decrease of the FRC whereas at the same time the LCI, an index for ventilation distribution, increased indicating an increased vulnerability to hypoxaemia.

Nurse-Assisted Propofol Pump Infusion for Sedation in ERCP Procedures: Is Anesthesiologist Necessary?

Introduction: Propofol has been profusely used for sedation in endoscopic procedures. In therapeutic procedures, such as endoscopic retrograde chonlangio pancreatography (ERCP), the general practice for sedation is to administer midazolam and petidine under the control of the endoscopist or sedation supervised by anaesthesiologist. Nurse-assisted propofol sedation in ERCP could be cost-effective and safe method. Aims & Methods: From November 02 to April 05 Propofol or Midazolam + Propofol were used as a sedation during ERCP procedures. A nurse was assigned to assist and control the sedation. Propofol boluses, plus Midazolam in some cases, followed by a continuous pump infusion of propofol were administered. Data prospectively recorded were: age, gender, ASA, therapeutic or diagnostic ERCP (and type), tolerance, endoscopist assessment of ERCP feasibility, arterial pressure, cardiac frequency and minimum oxygen saturation. Significant and minor complications during the procedure were recorded. Results: 506 patients whit mean age 72.1 (31.8% > 80 years old), 48.6% females were included in this study. Therapeutic ERCP (papillotomy, stone removal or stent insertion) was performed in 75.7% and 49.6 were ASA 3-4. Mean dose of propofol was 232 ± 120 mg. Midazolam (1-5 mg) was administered in 16.4%. Tolerance, rated by the patient was good or very good in 98% and ERCP feasibility was good or very good in 96%. Sat O2 < 90 occurred in 13%, BP < 90 in 3.4%, tachycardia in 20.1% (2.4% >120 bpm), and episodes of bradichardia <50 in 0.8%. Overall significant complications occurred in 31 patients (6.1%) with 34 events. Only in one case endoscopy removal and resuscitation measures were necessary. Furthermore, there have been 16 oxigen desaturatuions (47.1%), 6 vomits (17.6%), 4 requiring secretion aspiration. In addition, there were 12 events (35.3%) of significant hemodinamic instability (7 tachicardia, 3 hypotension and 2 bradichardia). Neither intubation nor anesthesic assistance were required in any case. Unespectedly, episodes of hypotension, taquichardia, Sat O2 <90 or significant complications were not more frequently in patients ASA 3-4 or aged >80. Conclusion: Nurse-assisted Propofol-pump infusion is safe and most likely, a cost effective method of sedation during therapeutic ERPC even in high ASA grade or elderly patients

Every Breath You Take, We’ll Be Watching You

Every Breath You Take, We’ll Be Watching You

Pharmacokinetics of a Single Bolus of Propofol in Chinese Children of Different Ages

Survey of Anesthesiology: February 2007 - Volume 51 - Issue 1 - p 43-44 doi: 10.1097/SA.0b013e31802f8c46

Propofol reduces tissue-Doppler markers of left ventricle function: a transthoracic echocardiographic study

Propofol is thought to minimally depress myocardial function, but mainly to reduce blood pressure by vasodilation. Transthoracic tissue-Doppler echocardiography (TDE) is a novel, validated method of quantifying myocardial function. It provides new insight into myocardial function by measuring myocardial motion. We examined the effects of propofol upon myocardial function by measuring changes in left ventricle function by TDE. We assessed change in myocardial function in propofol anaesthetized ASA I patients tissue tracking displacement (TTD) before anaesthesia onset and repeated measurements after a single propofol bolus dose. Tissue tracking score (TTS), a marker of ejection fraction, was also used (n = 10). Propofol 1.5-2 mg kg(-1) significantly attenuated PSV from 5.64 (1.17) to 4.66 (0.55) cm s(-1) (P < 0.0001) and TTD from 10.2 (2.1) to 8.5 (1.4) mm (P = 0.0091), whereas TTP was unchanged [all data: mean (SD)]. TTS declined from 7.2 (1.3) to 6.1 (0.6) mm (P < 0.01). Non-invasive mean blood pressure declined 17% (P < 0.0001). The results indicate that myocardial contractile function is compromised concomitantly with reduced cyclic displacement after propofol dosing. Blood pressure declined accordingly. From these results, it is impossible to ascertain whether this was secondary to reduced cardiac filling or a consequence of a direct negative inotropic action of propofol, but it represents a left-shift of the Starling curve. The novel TDE yields new information on myocardial velocities and motion.

Initial experience with dexmedetomidine for diagnostic and interventional cardiac catheterization in children

Children undergoing diagnostic and interventional cardiac catheterization require deep sedation or general anesthesia (GA). Dexmedetomidine, a selective alpha-2 adrenergic agonist, has sedative, analgesic and anxiolytic properties without respiratory depression. These characteristics make it potentially suitable as a sedative agent during diagnostic procedures in children. We report our experience using dexmedetomidine in 20 children aged 3 months to 10 years undergoing cardiac catheterization. Following a midazolam premedication, intravenous access was secured facilitated by the inhalation of sevoflurane in oxygen. A loading dose of 1 microg x kg(-1) dexmedetomidine was administered over 10 min followed by an initial infusion rate of 1 microg x kg(-1) x h(-1). Nasal cannulae were applied, allowing endtidal CO2 monitoring with the patients breathing spontaneously. Hemodynamic parameters, Bispectral Index Score (BIS) and sedation score were measured every 5 min. Patient movement or evidence of inadequate sedation were treated with propofol (1 mg x kg(-1)). The dexmedetomidine infusion rate was titrated to the level of sedation to a maximum of 2 microg x kg(-1) x h(-1) to maintain a sedation score of 4-5 and a BIS value <80. Five patients (25%) had some movement on local infiltration or groin vessel access. This did not necessitate restraint or result in difficulty securing vascular access. No patients failed sedation that required the addition of another sedative agent or conversion to GA; eight patients were sedated with dexmedetomidine alone; however, 12 (60%) patients did receive a propofol bolus at some time during the procedure due to movement, increasing BIS value or in anticipation of stimulation. There were no incidences of airway obstruction or respiratory depression. In all cases the heart rate and blood pressure remained within 20% of baseline. No patient required treatment for profound bradycardia or hypotension. The average infusion rate for dexmedetomidine following the loading dose was 1.15 (+/-0.29)microg x kg(-1) x h(-1) (range 0.6-2.0 microg x kg(-1) x h(-1)). This initial experience showed dexmedetomidine, with or without the addition of propofol, may be a suitable alternative for sedation in spontaneously breathing patients undergoing cardiac catheterization.

Sedation in patients above 60 years of age undergoing urological surgery under spinal anesthesia

Propofol and midazolam are commonly used sedatives during regional anesthesia in adults. Smaller doses of these drugs are required in older age due to altered pharmacokinetics and pharmacodynamics. To study the sedation, side-effects and the costs involved with smaller doses of propofol and midazolam in patients aged above 60 years during spinal anesthesia. A randomized single-blind study was conducted in 60 ASA I-II patients aged > or = 60 years undergoing urological surgery under spinal anesthesia. Sedation was administered after spinal anesthesia using propofol (bolus 0.4 mg.kg -1; infusion 3 mg/kg/hr) or midazolam (bolus 0.02 mg/kg; infusion 0.06 mg.kg -1.h -1) and titrated to achieve a sedation score of 3 on the modified Observer's Assessment of Alertness/Sedation Scale. Perioperative sedation, hemodynamics and respiratory events were monitored. The analysis for parametric data was done using Student's unpaired t test and the incidence data using Chi-square test. The onset (13.0+/-4.2 vs. 18.8+/-4.2 min, P < 0.001) and offset (8.9+/-2.8 vs. 12.5+/-3.5 min, P < 0.001) of sedation were faster and the duration of adequate sedation longer (44.7+/-12.5 vs. 29.8+/-12.9% of total infusion time, P < 0.001) with propofol than midazolam. More patients receiving propofol compared to midazolam had hypotension (16 [50%] vs.4 [14.3%], P= 0.003). Airway obstruction occurred frequently in both the groups. Sedation was significantly more expensive with propofol than midazolam (US$ 9.83 +/- 2.80 vs. US$ 0.33 +/- 0.06, P 0.001). Propofol provided better titration and adequacy of sedation than midazolam in patients above 60 years of age, but caused hypotension. Lighter sedation is recommended in this age group.

The Effects of Midazolam or Propofol Combined with Remifentanil Infusion for Central Venous Catheterization in Children

Background: Midazolam or propofol has been used for the procedural sedation in children. However, the combined use of remifentanil have not been widely investigated. The purpose of this study was to evaluate the effectiveness and safety of remifentanil infusion with intravenous anesthetics during the central venous catheterization in children. Methods: After institutional review board approval and written informed consent from patients` parent, 20 children planned central venous catheterization for chemotherapy were randomly assigned into two groups. All patients were infused with remifentanil 0.1μg/kg/min. In M group, 0.3 mg/kg of midazolam bolus was injected and 0.1 mg/kg bolus were injected intermittently if the sedation was inadequate. In P group, 1.0 mg/kg of propofol bolus and 150μg/kg/min were infused. 0.5 mg/kg of propofol was given intermittently if the sedation was inadequate. Hemodynamic variables, end-tidal CO2 (EtCO2), bispectral index score (BIS) were monitored throughout the procedure. Results: There were no significant differences in hemodynamic variables, sedation and recovery times. Oxygen saturation (SpO2) in P group was significantly lower than that of M group at 15 min after the start of infusion. EtCO2 in P group was significantly higher than that of M group at 10 min after the start of infusion. Hypoxemia (SpO2＜90%) were occurred in three patients of P group. There was no significant difference in BIS among the groups. Conclusions: The combined infusion of remifentanil 0.1μg/kg/min with midazolam provided successful sedation without airway assistance during the central venous catheterization in children. (Korean J Anesthesiol 2007; 52: 669~74)

Propofol and remifentanil for deep sedation in children undergoing gastrointestinal endoscopy

The aim of this study was to evaluate the safety and efficacy of a combination of propofol and remifentanil deep sedation in spontaneously breathing children less than 7 years of age undergoing upper and/or lower gastrointestinal endoscopy. The effect of propofol and remifentanil sedation was prospectively studied in 42 unpremedicated children undergoing gastrointestinal endoscopy. Anesthesia was induced with a combination of sevoflurane, nitrous oxide and oxygen. Anesthesia was maintained with an infusion of propofol (50-80 microg x kg(-1) x min(-1)) and remifentanil (0.1 microg x kg(-1) x min(-1)). Demographic data, heart rate, blood pressure, respiratory rate, and oxygen saturation were recorded every 5 min for each child. In addition, recovery and discharge times were recorded. All 42 procedures were completed with no complications. The combination of propofol and remifentanil resulted in a decrease in heart rate, blood pressure, and respiratory rate. There was no respiratory depression or oxygen desaturation in any child. A bolus of propofol (1 mg x kg(-1)) was necessary in one child for excessive movement. No patient experienced any side effects in the recovery period. The combination of propofol and remifentanil for sedation in children undergoing gastrointestinal endoscopy can be considered safe, effective and acceptable.

The Influence of Injection Rate on the Hypnotic Effect of Propofol during Anesthesia: A Randomized Trial

Objective:Previous studies suggested that slow injection of propofol may increase the hypnotic effect during induction of anesthesia. The aim of the present study was therefore to investigate whether injection rate of propofol has an influence on its maximum effect.Design:Randomized, single-blind trial.Setting:This study has been carried out in the operating rooms of a university hospital. An anesthesiologist and a resident performed the study with the aid of changing nursing staff.Participants:We investigated 99 unpremedicated patients aged 18 to 60 years with American Society of Anesthesiologists (ASA) physical status 1–3.Interventions:Anesthesia was induced by intravenous injection of propofol (2 mg/kg). Propofol was manually injected in group 1 over a period of 5 s; in group 2 (120-s injection interval), and in group 3 (240-s injection interval), propofol was administered by an injection pump. After loss of consciousness, mask ventilation was performed with 100% oxygen. Bispectral index (BIS) was used to measure the hypnotic effect of propofol. After the decrease of BIS to the minimum value (i.e., maximum hypnotic effect) and the following increase of BIS to 60, the study period was finished and anesthesia was performed according to clinical criteria.Outcome Measures:We analyzed whether injection speed has an influence on the maximum hypnotic effect of a given dose of propofol (2 mg/kg).Results:BISmin marks the maximum electroencephalogram (EEG) effect of the propofol bolus as measured by the BIS. The lowest mean BISmin was measured in group 1 (28.7 ± 10.3). In group 2, BISmin was 33.0 (±13.9), and in group 3, BISmin was 36.4 (±11.0). There were no significant differences between group 2 and groups 1 or 3, but there were significant differences between groups 1 and 3. In group 1, BISmin was reached after 102.91 s (±44.20), in group 2 after 172.33 s (±29.76), and in group 3 after 274.21 s (±45.40). These differences were statistically significant for all comparisons. In summary, the lowest value for BISmin was achieved in the group with the fastest rate of propofol injection (group1, 5 s). The highest BISmin was obtained in the group with the slowest rate of injection (group 3, 240 s). The hemodynamic parameters were not significantly different among groups.Conclusions:The hypnotic peak effect of propofol is lower with extremely slow injection (240 s versus 5 s). For clinically usual injection rates (5 s and 120 s), there was no significant difference in propofol peak effect.

Bolus Configuration Affects Dose Requirements of Intracarotid Propofol for Electroencephalographic Silence

We hypothesized that an intracarotid bolus injection of propofol to produce electroencephalographic (EEG) silence would require a smaller dose of the drug compared with the continuous infusion of the drug. Furthermore, the bolus propofol dose will be a function of the bolus characteristics in each bolus (mass/volume). We compared the dose requirements of intracarotid propofol needed to maintain EEG silence when delivered as bolus injections to continuous infusions in rabbits. Subsequently, we compared whether four different bolus characteristics (concentration and volume) of propofol (0.33% x 0.1 mL, 0.33% x 0.3 mL, 1% x 0.1 mL, and 1% x 0.3 mL) affected the dose required to produce EEG silence. We found that the infusion rate of propofol required to sustain EEG silence was three-fold larger than the dose required by bolus injections, 22.8 +/- 11.9 vs 6.2 +/- 2.9 mL/h for infusion versus bolus, respectively (n = 7, P < 0.004). Furthermore, during bolus injection, the doses of propofol required to produce EEG silence were a direct function of the bolus volume and the mass of drug in each bolus, total dose = 3.6 + 29 x mg/bolus, n = 32, r = 0.85. For maximum regional effects of the bolus intracarotid drug injection, the bolus characteristics (volume and drug concentration) have to be optimized.

Anesthesia for pediatric gastroscopy: a study comparing the ProSeal laryngeal mask airway with nasal cannulae

We tested the hypothesis that pediatric gastroscopy is more successful using the ProSeal laryngeal mask airway with the drain tube as a conduit to the stomach (ProSeal LMA group) than using nasal cannulae with conventional oral access to the stomach (NC group). Sixty children were consecutively and randomly allocated into each group. Patients breathed spontaneously and were given sevoflurane/air/oxygen mixture with propofol 1 mg.kg-1 boluses, as required. Anesthesia was provided by experienced users of both techniques. The following data were collected by an unblinded observer: operation and anesthesia times; cardiorespiratory data; adverse events; and recovery scores. In addition, the surgeon scored the ease of performing the procedure. The mean (range) age and weight was 74 (24-144) months and 26 (10-61) kg. Operation (15 min vs 24 min, P<0.0001) and anesthesia (22 min vs 37 min, P<0.0001) times were shorter in the ProSeal LMA group, but propofol bolus requirements per unit time were similar. Oxygen saturation was higher in the ProSeal LMA group (100% vs 94%, P<0.0006), but other cardiorespiratory variables were similar. There were no differences in the ease of performing the procedure. Hypoxia occurred more frequently in the NC group (20% vs 0%). Recovery scores were similar. We conclude that pediatric gastroscopy is quicker and has fewer airway complications when performed through the ProSeal LMA than using nasal cannulae and a conventional approach by experienced users.

Propofol/Midazolam Vs Propofol/Ketamine in Patients Undergoing Gastrointestinal Endoscopies

Introduction: Propofol/Midazolam has been shown to be a satisfactory anesthetic combination for patients undergoing gastrointestinal endoscopies. Ketamine (K) is a “new old” anesthetic agent which can be used as an analgesic adjunct to Propofol (P). Aim: The current study was aimed at comparing Propofol/Midazolam with Propofol/Ketamine and Ketamine impact on analgesia, sedation and recovery in this special setting. Materials and Methods: The study was randomized, blinded to the gastroenterologist, control-group. After Ethics Committee approval and informed consent, 108 consecutive patients scheduled for gastrointestinal endoscopies were randomly assigned to receive either Propofol/Midazolam (group A) or Propofol/Ketamine (group B). In group A, the patients received a premedication of 1-2 mg midazolam IV and then Propofol according the following protocol : induction dose of 1-2 mg/ kg titrated to immobility followed by a continuous infusion (100 μg / kg / min). In group B, the patients received an analgesic dose of Ketamine (25 mg IV) followed by Propofol according to the same protocol as in group A. In both groups, if movement occurred a bolus of Propofol was given (half the induction dose) and the rate of the infusion increased. At the end of the procedure, Propofol was discontinued. Throughout the procedure the patients were kept on oxygen mask and spontaneous breathing. Data recorded included age , gender, ASA class, weight, procedure (1 = endoscopy; 2 = endo+colon; 3 = colonoscopy; 4 = ERCP; 5 = EUS), time of procedure, time to eyes opening from end of procedure, doses of Propofol, physician satisfaction (score: 1- very high, 2- high , 3- low), movements during procedure (score :0- no, 1- minimal, 2- many), side effects(hallucinations, salivation, apnea, other), SaO2, heart rate.p < 0.05 was considered significant (Ttest analysis). Results: Both groups were equivalent for demographic data and type of procedure. Eyes opening time from end of procedure was 0.22 min in group B vs. 1.7 in group A (p < 0.05), which can be explained by the lower dose of P in group B (252.22 vs 179.72, p = 0.0003). The procedures were shorter in group B (28 min) than in A (22 min). The physician satisfaction was higher in group B (89%) than in group A (68%). Conclusions: The use of Ketamine in sub hypnotic dosages during Propofol sedation provides a good adjuvant, improving patient comfort, suppressing the need for supplemental opioids and decreasing the total dose of Propofol, allowing faster recovery and return to daily life. Therefore Propofol/Ketamine is an effective combination during gastrointestinal endoscopies which increases the turn over in the gastro clinic.

Development of a recursive finite difference pharmacokinetic model from an exponential model: Application to a propofol bolus

Propofol is commonly administered, as a single bolus dose, for the induction of general anesthesia. The purpose of this study was to mathematically assess the ability to model propofol induction-dose serum levels with a recursive finite difference equation (RFDE). Using data obtained from a prior published study, propofol induction pharmacokinetics were accurately modeled, on a subject-specific basis, with a third-order homogeneous finite difference equation with constant coefficients: P(k+3)=AP(k+2)+BP(k+1)+CP(k). Furthermore, each RFDE model is derived directly from the coefficients of a traditional three-compartment pharmacokinectic exponential equation. Based on this study, third-order RFDE models can have identical accuracy as three-compartment exponential models. In this particular application, it should be noted that each RFDE model required only three coefficients whereas each exponential model required six. Also, there was overall less patient-to-patient variability of the coefficients of the RFDE models. In general, it appears that RFDE models uniquely allow for predicting subsequent drug levels from preexisting ones. However, RFDE models require initial conditions whereas exponential models do not. Additional studies and applications of exponentially-derived RFDE pharmacokinetic models may be warranted.

Acute venous thrombosis caused by lipid‐free propofol

Recently, lipid-free propofol with thiomersal as a preservative (Cleofol 1%®, Themis Pharmaceuticals, Mumbai, India) has become available in India. Venous thrombosis of the upper limb was caused by this agent in a patient requiring radiofrequency lesioning for trigeminal neuralgia. A 55-year-old, well-controlled (metoprolol) hypertensive woman was administered lipid-free propofol (Cleofol) 1.5 mg.kg−1 through a 20 G intravenous cannula positioned in the left forearm. The patient complained of severe pain in the forearm and arm at the time of injection, which subsided after flushing the cannula with normal saline. Two subsequent injections of propofol during lesioning also caused severe pain. Following the fourth bolus of propofol injected during lesioning, the patient woke up with excruciating pain in the limb. The superficial veins of the left forearm became prominent, tender, cord-like and the peripheral blood oxygen saturation (Spo2) monitored from the left index finger decreased to 78–80% (compared with 96–98% on the right side). The left forearm and hand were swollen, dusky blue and cold. There was a retrograde flow of blood into the intravenous giving set. The intravenous infusion in the left forearm was discontinued and a new line started on the right hand. Efforts to flush the cannula in the left forearm were unsuccessful, but on aspiration, a 5 cm blood clot was removed. Heparin 10 000 IU was injected as a bolus and an intravenous infusion of 5% dextrose with nitroglycerine at a rate of 5–8 μg.min−1 was started. Nifedipine 5 mg was administered orally. The Spo2 in the affected limb improved to 93–96% and the pain decreased over a period of 20 min. A similar episode of pain and cyanosis of the limb occurred 30 min after the first episode. Doppler examination revealed a block of the brachial vein at the left antecubital fossa and compression of the brachial artery by grossly engorged brachial veins. A second dose of heparin 10 000 IU was administered followed by 1000 IU.h−1 for the next 24 h. The patient's symptoms were relieved 20 min after the second episode. The oedema of the left upper limb resolved over a period of 48 h. The signs and symptoms in our patient were caused by thrombosis of the deep brachial veins. The reduction in Spo2 in the affected limb was probably related to the compression of brachial artery by engorged brachial veins and also by oedema due to deep venous obstruction. Pain, vascular changes [1] and thrombophlebitis [2] have been reported after administration of propofol formulations without soya bean oil. Tissue necrosis following extravasation of propofol has also been reported [3]. Activation of the kallikrein–kinin system in plasma with subsequent generation of bradykinin that acts locally to dilate the vein and increase its permeability has been reported [4]. This may explain the escape of the drug, leading to damage to the surrounding tissues, tissue oedema and subsequent arterial compromise. This report poses serious questions about the safety of lipid-free propofol.

Clinical analysis of propofol deep sedation for 1,104 patients undergoing gastrointestinal endoscopic procedures: A three year prospective study

To analyze the hemodynamic and respiratory effects of propofol on patients undergoing gastroscopy and colonoscopy. In this prospective study, conducted over a period of three years, 1,104 patients referred for a same day GI endoscopy procedure were analyzed. All patients were given a propofol bolus (0.5-1.5 mg/kg). Arterial blood pressure (BP) was monitored at 3 min intervals and heart rate and oxygen saturation (SpO2) were recorded continuously by pulse oximetry. Analyzed data acquisition was carried out before, during, and after the procedure. A statistically significant reduction in mean arterial pressure was demonstrated (P < 0.001) when compared to pre-intervention values, but severe hypotension, defined as a systolic blood pressure below 60 mmHg, was noted in only 5 patients (0.5%). Oxygen saturation decreased from 96.5% to 94.4 % (P < 0.001). A critical decrease in oxygen saturation (< 90%) was documented in 27 patients (2.4%). Our results showed that propofol provided good sedation with excellent pain control, a short recovery time and no significant hemodynamic side effects if carefully titrated. All the patients (and especially ASA III group) require monitoring and care of an anesthesiologist.

Pharmacokinetics of a Single Bolus of Propofol in Chinese Children of Different Ages

There is no information about the pharmacokinetic profile of propofol in Chinese children younger than 3 yr. This study was designed to determine a complete pharmacokinetic profile of a single dose of propofol in Chinese children of different ages. Arterial blood samples were obtained from 35 children with an American Society of Anesthesiologist physical status of I or II at 2, 4, 6, 8, 10, 20, 30, 45, 60, 90, 120, and 180 min after a single bolus intravenous injection of propofol (3 mg/kg). The plasma concentrations of propofol were measured using high-performance liquid chromatography with an ultraviolet detector. A population model was used to estimate the pharmacokinetics of propofol. A three-compartment pharmacokinetic model best described the pharmacokinetics of propofol. Clearance was 0.185 l/min, the volume of distribution of the central compartment was 7.41 l, the peripheral volumes of distribution were 54.6 and 7.2 l, and the intercompartmental clearances were 0.614 and 0.692 l/min for a child of the average weight of 13.7 kg. The half-lives were 2.67, 14.89, and 310.60 min. Covariate models were applied, and weight was found to be significant covariate for the clearance and volume of distribution parameters. No significant age effect could be demonstrated on clearance or volume of distribution parameters after weight was taken into account. This study supports the case that the pharmacokinetic properties of propofol do not differ substantially across Chinese children of different ages after weight has been accounted for.

A New Inguinal Approach for the Obturator Nerve Block

Obturator nerve block is highly recommended for knee surgery in addition to a femoral nerve block. The main disadvantage of the classic approach at the pubic tubercle is low patient acceptance due to pain and discomfort. The authors hypothesized that the use of a new inguinal obturator nerve block technique would reduce pain and discomfort in patients. The inguinal approach was simulated in five fresh cadavers. Injection of latex was performed in two cadavers. The location of the needle and the extent of latex solution were analyzed. Fifty patients scheduled to undergo arthroscopic knee surgery were randomly assigned to receive obturator nerve block using either the inguinal (n = 25) or the pubic tubercle approach (n = 25). In all cadavers, the needle was close to the obturator nerve branches, which were surrounded by the latex solution. In the clinical study, visual analog scale pain scores and discomfort of block placement were significantly lower in the inguinal group compared with the pubic tubercle group (P < 0.01). In the inguinal group, there was a significant decrease in block performance time (P < 0.05) and in bolus of propofol and fentanyl used for the procedure (P < 0.01). Twenty minutes after application of the block, adductor strength decrease, occurrence, and location of cutaneous distribution of the obturator nerve were not significantly different between the groups. The incidence of minor complications was significantly increased in the pubic tubercle group (P < 0.05). No major complications were observed. The new inguinal approach decreases patient discomfort and pain of block placement as well as the time and sedation and analgesics required for a similar quality of sensory and motor block compared with the pubic tubercle approach.

Significance of patient-controlled sedation during colonoscopy: Results from a prospective randomized controlled study

In France, general anesthesia is given to more than 90% of patients undergoing colonoscopy although in several countries sedation is limited to intolerant patients. This study was carried out to determine whether Patient-Controlled Sedation (PCS) could provide a lighter sedation than general anesthesia adapted to the patient's individual requirement. Patients aged from 18 to 80 scheduled for elective colonoscopy were prospectively randomized to receive either standard sedation (control group) or patient-controlled-sedation (PCS). In the control group, patients received a continuous infusion of propofol. Patients in the PCS group were connected to an infusion pump containing propofol and self-administered 20-mg boluses as often as they required. An anesthetist was present throughout the procedure. Patient satisfaction measured on a visual analog scale four hours after colonoscopy was the main outcome criterion. From December 2002 to September 2003, 402 patients underwent elective colonoscopy, 173 of them were eligible and were asked to participate in the study. Seventy-two gave their informed consent and were prospectively randomized. The patients' mean satisfaction scores were not statistically different between the two groups: 84.7 mm (PCS group) vs. 91.5 mm (control group); P = 0.24. Mean doses of propofol (60 mg vs. 248 mg; P <0.001), depth of sedation and time before discharge (1.75 hours vs. 4.45 hours) were significantly lower for patients in the PCS group; nine of them (25.7%) did not use the pump and had total colonoscopy without sedation. There were no statistically significant differences between the two groups regarding total duration of colonoscopy (19.4 min (PCS) vs. 18 min (control)) difficulty and therapeutic procedures (biopsy or polypectomy). Two weeks after the procedure, 96.5% of patients in the PCS group were willing to repeat the examination under the same conditions vs. 72.5% of patients in the control group (P = 0.03). Our results demonstrate that need of sedation is widely overestimated in France. A subset of our patients is willing to consider colonoscopy without general anesthesia. For them, PCS with propofol is an effective and very well accepted form of sedation.