Mean Propofol Infusion Rate Research Articles

Comparison of propofol infusion rate required to abolish swallowing or pedal withdrawal reflexes in dogs.

In a prospective, randomized, experimental non-blinded study, the continuous infusions rates of propofol required to prevent swallowing (P-SR) or pedal withdrawal reflex (P-WR) were evaluated in healthy premedicated dogs. Dogs were randomly assigned to one of two treatments at weekly intervals. Following premedication with a combination of acepromazine and methadone, anesthesia was induced with propofol (4.00 mg kg-1 per min) and was maintained for 90 min. The propofol infusion rate was increased or decreased by 0.05 mg kg-1 per min based on positive or negative swallowing (P-SR) or pedal withdrawal reflexes (P-WR). Propofol induction doses were 2.12 ± 0.43 mg kg-1 (P-SR) and 2.14 ± 0.31 mg kg-1 (P-WR), which were not significantly different. The mean (±SD) propofol infusion rate was significantly higher for P-WR (0.26 ± 0.10 mg kg-1 per min) when compared to P-SR (0.22 ± 0.12 mg kg-1 per min). During the last 30 min, the mean propofol infusion rates were 0.09 ± 0.02 and 0.18 ± 0.03 mg kg-1 per min for P-SR and P-WR, respectively. There were no significant differences between treatments with respect to heart rate (HR), respiratory rate, arterial blood pressure, end-tidal CO2 partial pressure, hemoglobin oxygen saturation, partial pressures of oxygen or pH. Transient apnea lasting up to three minutes was observed in three dogs with each treatment. Propofol infusion rate of 0.22 ± 0.12 mg kg-1 per min can be used in premedicated dogs requiring tracheal intubation and undergoing mechanical ventilation, non-painful procedures or painful procedures with local anesthetic techniques.

Target-controlled propofol infusion with or without bispectral index monitoring of sedation during advanced gastrointestinal endoscopy.

Target-controlled infusion (TCI) uses averaged pharmacokinetic datasets derived from population samples to automatically control the infusion rate. Bispectral index (BIS) technology non-invasively measures levels of consciousness during surgical procedures. We compared the efficacy and safety of propofol TCI with or without BIS monitoring for sedation during advanced gastrointestinal endoscopy. This prospective study enrolled 200 patients who were premedicated with midazolam 2mg and alfentanil 0.4mg before undergoing advanced gastrointestinal endoscopy. The initial target blood concentration of propofol was set at 1.0μg/mL, and adjustments of 0.2μg/mL were made as necessary to maintain moderate-to-deep sedation. Patients were randomized to either the BIS-blind group and evaluated for depth of anesthesia by monitoring scores of 1-2 on the Modified Observer's Assessment of Alertness/Sedation scale (n=100) or to the BIS-open group and monitored by BIS scores of 60-80 (n=100). The primary outcome was the total amount of propofol required to maintain anesthesia. Secondary outcomes were sedation-induced adverse events, recovery, and quality of sedation (endoscopist and patient satisfaction). The mean propofol infusion rate was significantly higher in patients not monitored by BIS scores than in those who were (5.44±2.12 vs 4.76±1.84mg/kg/h; P=0.016). Levels of satisfaction were higher for endoscopists who used BIS monitoring than in those who did not. Mean infusion rates were higher in propofol TCI without BIS monitoring compared with propofol TCI with BIS during advanced gastrointestinal endoscopy. Endoscopists expressed satisfaction with BIS monitoring.

Post-surgical Evaluation of the Analgesic Impact of Epidural Tramadol, when Associated with Levobupivacaine, in Bitches Undergoing Mastectomy and Ovariohysterectomy

Background:Mammary tumors are the most common neoplasms in female dogs. Surgical removal of the mammary gland chain is considered the standard treatment and is usually performed along with ovariohysterectomy (OH) to suppress ovarian hormonal influence. Mastectomies cause moderate to severe pain and require preferential multimodal analgesic protocols. The aim of this study was to compare the postoperative analgesic efficacy and the recovery times on female dogs undergoing mastectomies and OH between those treated with epidural levobupivacaine alone and those treated with associated doses of tramadol and anesthetized with propofol.Materials, Methods & Results:Eighteen female dogs were pretreated with acepromazine (0.03 mg/kg), using propofol (4 mg/kg)for induction andanesthesia maintenance. The dogs were randomly divided into three groups (n = 6) treated with epidural anesthesia with levobupivacaine alone at 1.5 mg/kg (GL) or associated with tramadol at doses of 2 mg/kg (GLT2) or 4 mg/kg (GLT4). After anesthesia,the mean propofol infusion rate for each groupwere calculed. During the postoperative period,the degree of analgesia according to the University of Melbourne Pain Scale for 6 hours were determined, considering seven time points for evaluation (M30, M60, M90, M120, M180, M240, and M360). Supplemental analgesia with morphine (0.5 mg/kg) to those dogs with scores ≥13 were provided. During the recovery period,the time intervals between the end of anesthesia, and the following events: extubation (EX), the first head movement (MC), and the establishment of sternal (PE) and quadrupedal (PQ) positions were measured. The data were subjected to the Friedman test for analysis of non-parametric variables within the same group and to the Mann–Whitney test for independent variables, comparing the mean scores between groups (statistical significance was set at P<0.05). In the GL group, a higher mean propofol infusion rate than in either the GLT2 or GLT4 groups were found. The EX, PE, and PQ times were similar between the groups with a lower MC interval (P=0.041) for dogs in the GLT2 group. The pain assessment revealed higher scores for dogs in the GL group than for those in the GLT4 group (M30 to M120 and M360). Over time, the initial scores increased after M90 (GL group) and afterM120 (in all groups) andadditional analgesia were required only in GL dogs.Discussion:Mammary tumors were more frequent in middle-aged and elderly female dogs, corroborating current literary data. Regarding anesthesia recovery, no differences in the time for extubation and sternal and quadrupedal positions were found, probably due to similar propofol infusion times and to similar metabolism among the dogs, independent of the higher mean infusion rates used in the group treated only with the local anesthetic. The post-surgical analgesic evaluation revealed lower pain scores in the groups in which tramadol was associated with levobupivacaine, in agreement with studies reporting its analgesic potential to approach surgical pain at doses ranging from 1 to 4 mg/kg. However, even lower scores with the highest dose of the proposed opioid were detected, suggesting improved effectiveness for occupying opioid and monoaminergic pathway receptors. Considering the results, epidural anesthesia with levobupivacaine and tramadol seems to provide adequate post-surgical analgesia for a minimum period of 6 hours, and the best comfort is obtained with a dose of 4 mg/kg of opioid.

Comparison of target-controlled infusion and manual infusion for propofol anaesthesia in children

BackgroundOne major criticism of prolonged propofol-based total i.v. anaesthesia (TIVA) in children is the prolonged recovery time. As target-controlled infusion (TCI) obviates the need to manually calculate the infusion rate, the use of TCI may better match clinical requirements, reduce propofol dose, and shorten recovery time. MethodsChildren of ASA grade 1, aged 1–12 yr, were recruited and randomly assigned to TCI or manual infusion. Children in the TCI group had propofol delivered by TCI. Children for manual infusion had a loading dose of 2.5 mg kg−1 with subsequent infusion rates of 15, 13, 11, 10, and 9 mg kg−1 h−1. Attending anaesthesiologists adjusted the propofol dosage to keep the Bispectral Index™ (BIS) between 40 and 60. ResultsSeventy-four children completed the study. The time taken to extubate the trachea after cessation of propofol was 15.1 (5.5) and 16.2 (6.1) min for children who had TCI and manual infusion, respectively (P=0.42). The mean propofol infusion rate was 16.7 [standard deviation (sd) 4.2] mg kg−1 h−1 in the TCI group and 14.6 (3.1) mg kg−1 h−1 in the manual infusion group (P=0.036). The percentage of time when BIS was >60 was significantly lower in the TCI than the manual infusion group [10.2% (18.4%) vs 23.2% (26.3%), P=0.016]. DiscussionUse of TCI led to higher propofol doses but not prolonged recovery time in children compared with manual infusion. It was associated with a greater percentage of time when the BIS was in the desired range and it may be an easier method for titration of propofol administration during anaesthesia or sedation. Clinical trial registrationChiCTR-IOD-16010147.

Clinical comparison of the effects of isoflurane or propofol anaesthesia on mean arterial blood pressure and ventilation in dogs undergoing orthopaedic surgery receiving epidural anaesthesia

The aim of this study was to compare the effects on mean arterial pressure (MAP) and ventilation of propofol total IV anaesthesia (TIVA) and isoflurane as anaesthetic maintenance in healthy dogs undergoing orthopaedic surgery, with epidural anaesthesia. Dogs were premedicated IM with dexmedetomidine (4μg/kg) and methadone (0.3mg/kg), induced with IV propofol (0.65–5mg/kg) and randomly assigned to be maintained with isoflurane (group I) or propofol (group P). Isoflurane end-tidal concentration (EtISO) and propofol infusion rate were adjusted during the surgery to maintain a suitable anaesthetic depth. All dogs received bupivacaine (1mg/kg) and morphine (0.1mg/kg) in the lumbosacral epidural space (total volume 0.2mL/kg). MAP was recorded every 5min during the procedure. Statistical analysis was performed using parametric (Student’s t test) and nonparametric (Mann–Whitney U-test, chi-square) tests, as appropriate.Anaesthetic maintenance in groups I and P was accomplished by providing a mean EtISO of 1.12±0.15% and a mean propofol infusion rate of 15.0±4.7mg/kg/h, respectively. MAP was significantly higher in group P than in group I (92±17mmHg versus 78±10mmHg; P=0.021). Eleven dogs in group P and two dogs in group I reached an EtCO2>7.3kPa, requiring mechanical ventilation (P=0.001). In combination with epidural anaesthesia, propofol TIVA improved MAP and is a suitable alternative to isoflurane in orthopaedic surgery of the hind limb in healthy dogs. Nevertheless, since it was associated with increased respiratory depression, mechanical ventilation should be available.

Target-controlled infusion of propofol and remifentanil combined with dexmedetomidine reduces functional endoscopic sinus surgery bleeding.

The aim of the present study was to investigate the effects of target-controlled infusion (TCI) of propofol and remifentanil combined with dexmedetomidine on functional endoscopic sinus surgery (FESS) bleeding and surgical field. 62 patients scheduled to undergo FESS were randomly divided into experimental group (intravenous 0.5 µg kg-1 h-1 dexmedetomidine after 0.5 µg kg-1 bolus within 15 min until the end of surgery) or control group (intravenous saline administration at the same dose). All patients underwent endotracheal intubation under general anesthesia with TCI of propofol and remifentanil for anesthesia induction and maintenance. During anesthesia, arterial pressure (MAP), heart rate (HR), intraoperative propofol and remifentanil dosage and intraoperative blood loss were recorded. Surgeons rated their satisfaction with the surgical field using the Numeric Rating Scale (NRS). Following surgery, visual analog scale (VAS) was assessed. During tracheal intubation and extubation, HR and MAP in the experimental group were significantly lower compared with the control group (P<0.05); HR was also significantly lower compared with the control group throughout surgery (P<0.05). The mean infusion rate of propofol and remifentanil was significantly lower in the experimental group compared with the control group (P=0.001 and P=0.045, respectively). Blood loss in the experimental group was significantly lower compared with the control group (P=0.007). NRS and VAS scores in the experimental group were significantly improved compared with control group (P<0.01). In conclusion, TCI of propofol and remifentanil for FESS combined with dexmedetomidine reduced intraoperative bleeding and improved the quality of surgical field compared with the same procedure without dexmedetomidine. Dexmedetomidine also reduced the increase in MAP and HR during tracheal intubation and extubation, and improved postoperative analgesia quality.

Continuous infusion of propofol or intermittent bolus of tiletamine-zolazepam in squirrel monkeys (Saimiri sciureus)

ObjectiveTo investigate an infusion of propofol for anesthesia in comparison to tiletamine-zolazepam anesthesia, evaluating physiological variables and recovery in squirrel monkeys. Study designProspective non-blinded randomized study. AnimalsEight healthy squirrel monkeys (Saimiri sciureus), aged 3 years and weighing 0.340–0.695 kg. MethodsPremedication was intramuscular midazolam (0.5 mg) and meperidine (4 mg). Anesthesia was induced with intravenous (IV) propofol (4 mg kg−1 minute−1) and maintained with propofol starting at 0.4 mg kg−1 minute−1 (PRO, n = 4) or IV tiletamine-zolazepam (5 mg kg−1) and maintained with supplementary doses of TZ (TZ, n = 4). Cardiopulmonary variables were measured continuously. Arterial blood gases and lactate concentration were measured at the end of anesthesia. Quality and times of recovery were determined. Repeatedly measured data for significant differences were tested between groups with t-test and within groups by anova. ResultsMedian time for induction of anesthesia in PRO was 180 seconds. Mean maintenance infusion rate of propofol was 0.43 ± 0.05 mg kg−1 minute−1, varying during the 1 hour period. One monkey died after administration of TZ; others required 1, 4, or 8 supplemental doses. Cardiopulmonary variables were similar between groups, but hypotension was recorded. Recovery times to ventral recumbency in PRO (32 ± 17 minutes) and TZ (84 ± 11 minutes) and normal ambulation in PRO (58 ± 22 minutes) and TZ (358 ± 109minutes) were significantly different (p < 0.05). Recovery quality was superior in PRO, with less ataxia and fewer unsuccessful attempts to stand. Lactate concentration was not different between treatments. Conclusions and clinical relevanceCardiopulmonary variables were similar between protocols, aside from the higher incidence of hypotension in PRO, indicating that further studies with a larger number of animals are required. Compared to tiletamine-zolazepam, propofol anesthesia provided faster and superior anesthetic recovery in these animals.

Comparison of rocuronium and succinylcholine on postintubation sedative and analgesic dosing in the emergency department

Rocuronium and succinylcholine are both commonly used neuromuscular blockers for rapid sequence intubation in the emergency department (ED). The objective of this study was to determine if patients who receive rocuronium are more likely to receive lower doses of postintubation sedatives and analgesics compared with patients who receive succinylcholine. This was a retrospective cohort study carried out in a tertiary, academic ED. Consecutive adult patients, who were intubated using etomidate for induction of sedation, were included. Patients were categorized on the basis of whether they received (a) rocuronium or (b) succinylcholine for paralysis. The dosing of postintubation sedative and analgesic infusions were compared 30 min after initiation between the two groups. A total of 254 patients were included in the final analysis (rocuronium=127 and succinylcholine=127). In the overall cohort, 90.2% (n=229) of patients were administered a sedative postintubation in the ED. Most of these patients were initiated on propofol infusions. The mean propofol infusion rate at 30 min was 30±23 mcg/kg/min in the rocuronium group and 42±24 mcg/kg/min in the succinylcholine group (P=0.002). A total of 42.5% of patients (n=108) received an analgesic infusion (all patients received fentanyl). The mean fentanyl infusion rate at 30 min was 0.65±0.55 and 0.86±0.49 mcg/kg/h in the rocuronium and succinylcholine groups, respectively (P=0.041). Patients who receive rocuronium are more likely to receive lower doses of sedative and analgesic infusions after intubation. This may place them at risk of being awake under paralysis.

Continuous infusion of propofol or intermittent bolus of tiletamine‐zolazepam in feline night monkeys (Aotus infulatus)

Although commonly used, dissociative anesthesia results in unsatisfactory and long recovery periods. The intravenous anesthetic propofol seems to be the most advantageous solution. The objectives of this study were to investigate the required infusion rate of propofol to maintain surgical anesthesia and to compare it to tiletamine-zolazepam in Aotus infulatus. Eight healthy feline night monkeys were anesthetized with propofol (PRO) or tiletamine-zolazepam (TZ) during 60minutes. Cardiopulmonary parameters, arterial blood gases and lactate and quality and times to recovery were determined. Mean infusion rate of propofol was 0.53±0.10mg/kg/minute. Cardiopulmonary effects did not show marked differences between groups. Times for hanging, ventral recumbency, and normal ambulation were lower in PRO. Establishment of desirable anesthetic depth was easier, recovery quality was superior, and lactate levels were lower in PRO. Compared with tiletamine-zolazepam, minor post-anesthetic adverse events should be expected with propofol anesthesia, as well as faster and better anesthetic recovery.

Propofol sedation administered by cardiologists without assisted ventilation for long cardiac interventions: an assessment of 1000 consecutive patients undergoing atrial fibrillation ablation

Patients can expect a cure from atrial fibrillation (AF) with ablation. Procedural safety and success depend on patient comfort, compliance, and immobility. This is difficult to achieve with benzodiazepine and opiate boluses that are the mainstay of current practice. We sought to determine the safety and efficacy of propofol infusion sedation administered to patients without assisted ventilation for AF ablation. Procedural data from 1000 consecutive patients undergoing AF ablation were analysed. Sedation with 2% propofol was used in all procedures without assisted ventilation and was administered, monitored, and controlled by electrophysiologists. Primary outcome measures were adverse sedative affects including (i) respiratory depression (SpO(2)< 90% for >20 s) and (ii) persistent hypotension [systolic blood pressure (SBP)<90 mmHg at minimum sedation level]. Secondary endpoints included full recovery within 60 min and procedural complications. Of 1000 ablations, 506 ablations were performed for persistent and 494 for paroxysmal AF. Average patient age was 60.1 ± 11.3 years (72.3% male). Propofol was commenced in all patients at a mean infusion rate of 18.5 ± 4.8 mL/h with a mean baseline SBP of 140.3 ± 19.9 mmHg. Mean procedure time was 148.7 ± 57.7 min. Adverse sedative effects necessitating cessation of propofol and switch to midazolam bolus sedation occurred in 15.6% of patients (13.6% due to persistent hypotension, 1.9% due to respiratory depression, and 0.1% due to hypersalivation). Patients who had persistent hypotension were older (62.9 ± 11.2 vs. 60.0 ± 11.4 years, P= 0.011) and more likely to be female (39.5 vs. 23.7%, P< 0.001) than those who tolerated propofol. Patient age correlated to maximum blood pressure drop with propofol (R(2)= 0.101, P< 0.001) and inversely correlated to mean propofol infusion rate (R(2)= 0.066, P< 0.001). No procedures were abandoned due to adverse effects of sedation. All patients recovered within 60 min. Serious procedural complications, unrelated to sedation, occurred in 0.5%, all of whom had pericardial tamponade successfully treated with percutaneous pericardiocentesis. Sedation with 2% propofol infusion administered by cardiologists without assisted ventilation is safe, effective, and practical for use in AF ablation without serious or residual complications. In this setting, persistent hypotension is the most common acute adverse effect requiring cessation of propofol in ∼14%.

Accumulated oropharyngeal water increases coughing during dental treatment with intravenous sedation

In dental procedures performed under intravenous sedation in patients with intellectual disabilities, procedures are sometimes interrupted by the cough reflex, which may be triggered by intraoral use of water and/or increased secretion stimulating the pharyngeal/laryngeal mucosa, or by those irritating the tracheal mucosa directly through anesthetics-induced impairment of the laryngeal closure reflex. We investigated relationships between frequency of coughing episodes and intraoral use of water, water remaining in the oropharyngeal space, and mean infusion rate of propofol during dental treatments performed under intravenous sedation with midazolam and propofol. Twenty-one intellectually disabled patients were enrolled. After induction, a 14 Fr. suction catheter was inserted nasally, which was fixed where oropharyngeal suction could be done most effectively. Patients were divided into three groups according to the amount of intraoral use of water, amount of oropharyngeal suction and mean infusion rate of propofol. The amount of oropharyngeal suction significantly correlated with intraoral use of water. Frequency of coughing episodes significantly correlated with amount of oropharyngeal suction per minute. However, coughing episodes correlated neither with intraoral use of water nor with infusion rate of propofol. These findings suggested that accumulation of water in the oropharynx increased vulnerability to the cough reflex in dental treatments performed under intravenous sedation.

Outpatient arthroscopic knee surgery under combined local and intravenous propofol anesthesia in children and adolescents

This prospective observational study included a case series of children and adolescents receiving light intravenous propofol anesthesia combined with local anesthesia (LA) for arthroscopic knee procedures. The aim was to examine the merits of anesthesia, to discuss the indications for the procedure and to analyze recovery/discharge times from the postanesthesia care unit (PACU). A cohort of 147 children and adolescents (ASA 1 and 2) aged 12-18 years admitted for outpatient arthroscopic knee procedures between January 2004 and May 2005 were studied. After IV access in the operating theater, the patients received propofol (10 mg.ml(-1)). Arthroscopy was performed approximately 15 min after injecting local anesthetic (15 ml 2% lidocaine with epinephrine 1:200,000) partly at the site of insertion of the arthroscope and other instruments (5 ml), and the rest intra-articular. The following parameters were assessed: airway patency, propofol requirement, vital signs, procedure time, surgical operating conditions, patient satisfaction score, time to discharge, postoperative analgesia and adverse events. Of 147 patients, 133 patients (90.5%) underwent arthroscopic knee surgery, whereas knee arthroscopy alone was performed in 14 patients (9.5%) without indication for operative treatment. The arthroscopy was well tolerated in 96.6% patients (no pain, movement or discomfort during the procedure) and only five patients required conversion to general anesthesia. Pain experienced during the injection of lidocaine was more severe than pain experienced during the surgical procedure itself (P < 0.001). The surgical evaluation of operative conditions (visualization and access to intra-articular structures) was generally satisfactory and completely acceptable. Almost 94% (138/147) of patients said they would have the same procedure again under the same type of anesthesia. The mean propfol induction dose was 1.4 mg.kg(-1) (range: 0.9-3.8) and mean propofol infusion rate 167 microg.kg(-1).min(-1) (range: 130-250). Movement was more likely at lower infusion rates (mean: 151 microg.kg(-1).min(-1)). The maximal decrease in respiratory rate was 5.9 +/- 5.1 br.min(-1) (27.2 +/- 21%) and no patient became hypoxic. Patients recovered to preoperative values at 9.8 +/- 7.5 min following infusion discontinuation. There were no respiratory or cardiovascular complications. The mean stay in PACU was 47 min (range: 32-150). As many as 71% (105/147) of patients required no analgesics during the first two postoperative hours. The combination of light intravenous propofol anesthesia combined with local anesthesia for arthroscopic knee procedures provided effective sedation, good preservation of upper airway patency, rapid recovery and pain relief without major side effects and offers a good alternative to the methods already available. The majority of patients did not require postoperative analgesia.

Propofol total intravenous anesthesia for MRI in children

The aim of this study was to assess clinical signs of airway patency, airway intervention requirements and adverse events in 100 children receiving propofol total intravenous anesthesia for magnetic resonance imaging, with spontaneous ventilation and oxygenation via nasal prongs. Airway patency was clinically assessed and stepwise interventions were performed until a satisfactory airway was achieved. Propofol requirements, vital signs, procedure times and adverse events were also recorded. Ninety-three per cent of children had no signs of airway obstruction when positioned with a shoulder roll only, two required a chin lift, four required an oral airway and one required lateral positioning. The mean propofol induction dose was 3.9 mg.kg(-1) (range 1.8-6.4 mg.kg(-1)). The mean propofol infusion rate was 193 microg.kg(-1).min(-1) (range 150-250 microg.kg(-1).min(-1)). The initial and final mean respiratory rates were 26 and 23 b.min(-1) (P < 0.05). Movement was more likely at lower infusion rates (mean 175 microg.kg(-1).min(-1)). There were no respiratory or cardiovascular complications (calculated risk: 95% CI = 0-3%). The mean time from end of scan to discharge home was 44 min. This study demonstrates good preservation of upper airway patency and rapid recovery using general anesthetic doses of propofol in children.

Effects of epidural anaesthesia–analgesia on intravenous anaesthesia with propofol

The main purpose of this study was to demonstrate that the use of epidural anaesthesia–analgesia reduces the amount of propofol necessary to maintain surgical anaesthesia in dogs during ovariohysterectomy. The study was carried out on 28 bitches undergoing ovariohysterectomy with general anaesthesia using an intravenous infusion of propofol. Dogs were allocated to one of two groups. Group 1 received systemic buprenorphine together with epidural analgesia using lidocaine and buprenophine, and in Group 2 systemic buprenorphine only was given. The mean propofol infusion rate was significantly lower in dogs with epidural analgesia ( P<0.0001). In addition, the mean endotracheal extubation time was significantly longer in dogs with epidural analgesia ( P<0.0001). No significant differences were detected in any of the physiological parameters measured.

Patient-Controlled Sedation for Local Anesthesia Patients in Plastic Surgery

Background: Patient-controlled sedation (PCS) involves the patient self administering the sedative agent to the point at which the patient is satisfied with the level of sedation with the advantage to overcome the phamacodynamic differences between individual patients. We performed the PCS with two different dosages of propofol and compared the efficacy and side effects for local anesthesia patients in plastic surgery. Methods: Thirty patients underwent propofol PCS with fm (B. Braun, Germany) PCA pump during nasal inhalation of 3 L/min with continuous monitoring of . PCS settings were 10 mg of bolus dose, 30 mg of initial loading dose, 1 min of lockout interval, 100 mg/hr of continuous infusion in group 1 and 20 mg of bolus dose, 60 mg of initial loading dose, 1 min of lockout interval, 100 mg/hr of continuous infusion in group 2. All the patients received local anesthesia with 1% lidocaine before operation. Observer's assessment of alertness/sedation (OAA/S) scale, , mean infusion rate of propofol, duration of induction and recovery, recall of operative procedure, and patient's and surgeon's satisfaction were checked. Results: The mean infusion rate (group 1; 32.2 19.4, group 2; 38.3 20.5 ug/kg/min), duration of induction (group 1; 4.9 1.9, group 2; 3.1 1.4 min), duration of recovery (group 1; 1.7 1.2, group 2; 2.5 1.3 min), and mean OAA/S scale (group 1; 3.8 1.6, group 2; 3.1 1.5) were not significantly different between the groups (mean SD). Inadequate sedation occurred more frequently in group 1 (13%) than group 2 (0%), and incidences of respiratory depression (

Diabetes attenuates the hemodynamic stabilizing effects of oral clonidine during off-pump coronary artery bypass surgery

Study objective To investigate the influence of diabetes mellitus on the hemodynamic-stabilizing effect of clonidine during off-pump coronary artery bypass (OPCAB) surgery. Design Prospective study. Setting Public, university-affiliated hospital. Patients 40 patients (32 male, 8 female) scheduled for OPCAB surgery. Interventions and measurements Patients were divided into equal groups of diabetic and nondiabetic patients. All patients were given 150 μg oral clonidine 1 hour before induction. Anesthesia was induced and maintained with fentanyl, propofol, and sevoflurane. Propranolol was administered intermittently to maintain an adequate heart rate (HR; 50 to 70 bpm). Preoperative demographic data (fasting blood glucose concentration and hemoglobin A1c), dose of intraoperative drugs (propofol and propranolol), and outcome data (duration of intubation and duration of hospital stay after surgery) were analyzed. Main results In the diabetic and nondiabetic groups, the mean (±SD) plasma glucose values were 7.8 ± 2.3 mmoL · L −1 and 5.4 ± 0.7 mmoL · L −1 , respectively (p < 0.05), and the mean (±SD) HbA1c values were 7.1 ± 1.3% and 5.2 ± 0.4%, respectively (p < 0.05). The mean propofol infusion rate was 2.8 ± 0.9 mg · kg −1 · h −1 in diabetic patients and 3.1 ± 1.0 mg · kg −1 · h −1 in nondiabetics (NS, p > 0.05). The total requirement for propranolol was 5.1 ± 2.4 mg in diabetic patients and 1.6 ± 1.1 mg in nondiabetics (p < 0.05). Conclusions Diabetes attenuates the hemodynamic stabilizing effects of preanesthetic oral clonidine in the clinical setting.

Evaluation of effects of magnesium sulphate in reducing intraoperative anaesthetic requirements

The present randomized, placebo-controlled, double-blind study was designed to assess the effect of peroperatively administered i.v. magnesium sulphate on anaesthetic and analgesic requirements during total i.v. anaesthesia. Eighty-one patients (36 women, 45 men) undergoing elective spinal surgery were included in one of two parallel groups. The magnesium group received magnesium sulphate 30 mg kg(-1) as a bolus before induction of anaesthesia and 10 mg kg(-1) h(-1) by continuous i.v. infusion during the operation period. The same volume of isotonic solution was administered to the control group. Anaesthesia was maintained with propofol (administered according to the bispectral index) and remifentanil (adjusted according to heart rate and arterial blood pressure) infusions. A significant reduction in hourly propofol consumption was observed with magnesium administration. For example, the mean infusion rate of propofol in the second hour of the operation was 7.09 mg kg(-1) h(-1) in the control group vs 4.35 mg kg(-1) h(-1) in the magnesium group (P<0.001). The magnesium group required significantly less remifentanil (P<0.001) and vecuronium (P<0.001). No side-effects were observed with magnesium administration. The administration of magnesium led to a significant reduction in the requirements for anaesthetic drugs during total i.v. anaesthesia with propofol, remifentanil and vecuronium.

This Month in ANESTHESIOLOGY

This Month in ANESTHESIOLOGY

This Month in ANESTHESIOLOGY

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Postoperative Sedation with Propofol Infusion

This study was designed to investigate the haemodynamic response and pharmacokinetics of a low-dose propofol continuous infusion in providing sedation in patients who required mechanical ventilation after coronary artery bypass grafting surgery. 22 male patients, aged between 45 and 65 years, were evaluated in an open, uncontrolled study. At the end of the surgical procedure, a low-dose (1 mg/kg/h) propofol infusion was started and adjusted to optimise sedation according to the Ramsay scale. The mean propofol infusion rate was 1.42 +/- 0.4 mg/kg/h. Electrocardiogram, systemic and pulmonary arterial pressure, and central venous pressure were monitored continuously. Left ventricular shortening fraction was calculated by transoesophageal echocardiography. Propofol plasma levels were calculated in 10 patients to evaluate the pharmacokinetics. Throughout the duration of the study all patients were haemodynamically stable. Sedation was maintained for 363 +/- 244 minutes and was adequate in all patients. The clinical recovery time (postsedation responsiveness) was 15.7 +/- 6.2 minutes, after infusion suspension. There was no correlation between propofol plasma levels or propofol infusion rate and the depth of sedation (respectively, r = 0.39 and r = 0.23), while there was a good correlation (r = 0.62) between propofol infusion rate and plasma levels. Open two-compartment model pharmacokinetics were demonstrated. Low-dose propofol infusion (1 to 2 mg/kg/h) proved to be well tolerated and effective in maintaining sedation after cardiac surgery. Sedation was quickly obtained without a propofol loading dose; steady-state plasma concentrations of 0.6 to 0.8 mg/L were rapidly achieved. Propofol pharmacokinetics ensure rapid clearance with rapid clinical recovery.