Propofol Bolus Research Articles

Population pharmacokinetics of a propofol bolus administered in patients with major burns

Objective In operating theaters and burn units, propofol is commonly used for sedation and anesthesia in patients with major burns. This study determined the population pharmacokinetics of propofol in burns and identified clinically significant covariates. Method Seventeen adults, age 42 ± 10 (mean ± SD) years, with 41 ± 19% total body surface area burns, were enrolled at 16 ± 14 days after-burn. Non-burn adults ( n = 19) served as controls. After an intravenous bolus of 2 mg/kg propofol, the plasma concentration was determined at designated times for up to 4.5 h. Concentration–time profiles were analyzed using nonlinear mixed-effect modeling. Results A three-compartment model gave the best fit. The volume of distribution of the central compartment ( V 1) was considerably greater in the burned than non-burned group (48.4 L vs. 27.6 L, respectively). The clearances of the central ( CL 1) and slow peripheral ( CL 3) compartments were higher in burn patients (4.2 L/min vs. 1.7 L/min and 3.6 L/min vs. 1.1 L/min, respectively). Adding the covariates BURN to V 1, CL 1, and CL 3 and WT (weight) to CL 1 significantly improved the model performance. Conclusion The pharmacokinetic characteristics of a propofol bolus administered in patients with major burns were enhanced clearance and expanded volume of distribution. BURN and WT were the important covariates. For sedation or anesthesia induction, a higher than recommended dose of propofol may be required to maintain therapeutic plasma drug concentrations in patients with severe burns. Vigilance regarding the burned individual and careful titration of hypnotics to the desired effect cannot be overemphasized.

Protective effects of ulinastatin on the lungs in patients with lung cancer undergoing lobectomy

Objective To investigate the protective effects of ulinastatn on the lungs in patients with lung cancer undergoing lobectomy. Methods Forty ASA Ⅱ or Ⅲ patients with stage Ⅲ lung cancer, aged 50-64 yr weighing 53-70 kg undergoing lobectomy were randomly divided into 2 groups ( n = 20 each): control group (group C) and ulinastatin group (group U). In group U ulinastatin 10 000 U/kg in 20 ml normal saline was infused iv over 30 min immediately after induction of anesthesia. The patients were premedicated with diazepam 10 mg and scopolamine 0.3 mg im. Anesthesia was induced with midazolam 0.05 mg/kg, fentanyl 4 μg/kg, TCI of propofol (Cp 4 μg/ml) and vecuronium 0.12 mg/kg and maintained with TCI of propofol (Cp 2-3 μg/ml) and intermittent iv boluses of fentanyl and vecuronium. The patients were intubated with double-lumen tube. Correct position of the tube was checked with fiberoptic bronchoscope. One-lung ventilation (OLV) was performed (VT 6-8 ml/kg, RR 10-16 bpm, I:R 1:2, FiO2 100% ). PETCO2 was maintained at 35-45 mm Hg. Arterial blood samples were taken before anesthesia (T0, baseline), at 0.5 h and 1 h of OLV (T1, T2 ) and 4 h and 24 h after operation (T3, T4 )for blood gas analysis and determination of plasma TNF-α, IL-6 and IL-10 concentrations. Respiratory index (RI)was calculated. (RI= PA-a O2 /PaO2 ).Results Compared with the baseline values at To, plasma TNF-α and IL-6 concentrations and RI at T1-4 and plasma IL-10 concentrations at T1-3 were all significantly increased in group C,while in group U plasma TNF-α and IL-6 concentrations at T2,3 and plasma IL-10 concentrations and RI at T1-4 were all significantly increased ( P ＜ 0.05 ). Plasma TNF-α and IL-6 concentrations and RI were significantly lower while plasma IL-10 concentration was significantly higher in group U than in group C (P ＜ 0.05).Conclusion Ulinastatin 10 000 U/kg can effectively protect the lungs in patients with lung cancer undergoing lobectomy by attenuating systemic inflammatory response. Key words: Trypsin inhibitors; Pneumonectomy; Lung neoplasms

Effectiveness, safety, and pharmacokinetic and pharmacodynamic characteristics of microemulsion propofol in patients undergoing elective surgery under total intravenous anaesthesia

The aims of this study were to investigate the effectiveness, safety, pharmacokinetics, and pharmacodynamics of microemulsion propofol, Aquafol (Daewon Pharmaceutical Co., Ltd, Seoul, Republic of Korea). In total, 288 patients were randomized to receive 1% Aquafol or 1% Diprivan (AstraZeneca, London, UK) (n=144, respectively). A 30 mg test dose of propofol was administered i.v. over 2 s for assessing injection pain. Subsequently, a bolus of propofol 2 mg kg(-1) (-30 mg) was administered. Anaesthesia was maintained with a variable rate infusion of propofol and a target-controlled infusion of remifentanil. Mean infusion rates of both formulations and times to loss of consciousness (LOC) and recovery of consciousness (ROC) were recorded. Adverse events and pharmacokinetic and pharmacodynamic characteristics were evaluated. Mean infusion rate of Aquafol was not statistically different from that of Diprivan (median: 6.2 vs 6.3 mg kg(-1) h(-1)). Times to LOC and ROC were slightly prolonged in Aquafol (median: 21 vs 18 s, 12.3 vs 10.8 min). Aquafol showed similar incidence of adverse events to Diprivan. Aquafol (vs Diprivan caused more severe (median VAS: 72.0 vs 11.5 mm) and frequent (81.9 vs 29.2%) injection pain. The dose-normalized AUC(last) of Aquafol and Diprivan was 0.71 (0.19) and 0.74 (0.20) min litre(-1). The V(1) of both formulations were proportional to lean body mass. Sex was a significant covariate for k(12) and Ce(50) of Aquafol, and for k(e0) of Diprivan. Aquafol was as effective and safe as Diprivan, but caused more severe and frequent injection pain. Aquafol demonstrated similar pharmacokinetics to Diprivan.

Total intravenous anesthesia and spontaneous respiration for airway endoscopy in children – a prospective evaluation

Inhalational anesthesia with spontaneous respiration is traditionally used to facilitate airway endoscopy in children. The potential difficulties in maintaining adequate depth of anesthesia using inhalational anesthesia and the anesthetic pollution of the surgical environment are significant disadvantages of this technique. We report our institutional experience using total intravenous anesthesia (TIVA) and spontaneous respiration. We prospectively studied 41 pediatric patients undergoing 52 airway endoscopies and airway surgeries. Following induction of anesthesia, a propofol infusion was titrated to a clinically adequate level of anesthesia, guided by the Bispectral Index (BIS), and a remifentanil infusion was titrated to respiratory rate. ECG, BP, pulse oximetry, BIS level, transcutaneous CO(2) (TcCO(2)), respiratory rate, and drug infusion rates were recorded. Adverse events and the response to these events were also recorded. Forty-one children underwent 52 airway procedures; 17 rigid bronchoscopies and 35 micro-laryngobronchoscopies, including 18 LASER treatments, were performed. The mean (sd) age was 6.9 (5.8) years and weight 26.9 (21.2) kg. The mean induction time was 13 (6) min, and anesthesia duration was 49 (30) min. The mean highest TcCO(2) recorded during the procedures was 62.8 +/- 15.3 mmHg. Coughing occurred in 14 (27%) patients, requiring additional topical anesthesia (3), a bolus of propofol (4) or remifentanil (1), or removal of the bronchoscope (1). Desaturation below 90% occurred in 10 (19%) cases; only three required intervention in the form of temporary assisted ventilation (2) or inhaled bronchodilators (1). No laryngospasm, stridor, or arrhythmias were observed. TIVA and spontaneous respiration is an effective technique to manage anesthesia for airway endoscopy and surgery in children.

Comparison of propofol versus propofol‐ketamine combination for sedation during spinal anesthesia in children: randomized clinical trial of efficacy and safety

This study was designed to compare the efficacy and safety of propofol vs propofol-ketamine combination for sedation during pediatric spinal anesthesia. Forty children, aged 3-8 undergoing spinal anesthesia for lower abdominal surgeries were included. Participants were randomly assigned into two groups. Group 1 received propofol bolus of 2 mg.kg(-1) followed by an infusion of 4 mg.kg(-1).h(-1). Group 2 received a combination of 1.6 mg.kg(-1) propofol and 0.4 mg.kg(-1) ketamine followed by an infusion of 3.2 mg.kg(-1).h(-1) and 0.8 mg.kg(-1).h(-1), respectively. The infusion rate was titrated to keep the child sedated at University of Michigan Sedation Score of 3. The heart rate, blood pressure, respiratory rate and oxygen saturation were recorded every 5 min. The episodes of spontaneous body movements and requirement of supplemental sedation were recorded. The postoperative recovery was assessed by modified Aldrette score. Seventeen patients in group 1 and four patients in group 2 (P < 0.001) required extra boluses of study drug to prevent movements during lumbar puncture. Four patients experienced respiratory depression and three airway obstruction in group 1 when compared to one patient each in group 2 (P < 0.05). The recovery time was similar in both groups. None of the patient had postoperative nausea/vomiting or psychomimetic reactions. Propofol-ketamine combination provided better quality of sedation with lesser complications than propofol alone and thus can be a good option for sedation during spinal anesthesia in children.

Effects of Propofol Intravenous Injection Bolus on the Left Ventricular Function and the Myocardial β-Adrenoceptor in Rats

Propofol bolus injection has been reported to influence cardiovascular functions. However, the detailed mechanism underlying this action has not been elucidated. This study was designed to investigate the effects of propofol i.v. bolus on the left ventricular function, the myocardial beta-adrenoceptor (beta-AR) binding-site density (Bmax) and Kd (apparent dissociation constant) in a 30-minute period. One hundred and four male Wistar rats were randomly divided into four groups: group C (control group), group I (intralipid group), group P1 (5 mg/kg propofol) and group P2 (10 mg/kg propofol). The results showed a significant downregulation of HR, LVSP, +dp/dtmax and -dp/dtmax in both groups P1 and P2 (especially after bolus injection in 7 min) than those of group C (P < 0.05), whereas no significant difference was found between the P1 and P2 groups (P > 0.05). Likely, Bmax was remarkably upregulated in both groups P1 and P2 (P < 0.05, vs. groups C and I), and there was no significant difference between these two groups (P > 0.05). Of note, the Kd value in group P2 (10 mg/kg propofol) was found dramatically increased in 30 min than that in the low-dose propofol-treated group (group P1) as well as in groups C and I (P < 0.05). In conclusion, these results indicate that intravenous injection of propofol bolus can inhibit the cardiac function partially via upregulation of Bmax and downregulation of the beta-AR affinity at higher-dose injection of propofol bolus.

Relationship between intracranial excitatory aminoacid levels and postoperative cognitive dysfunction in elderly patients after general anesthesia

Objective To investigate the relationship between the changes in intracranial excitatory amino acid(EAA) levels and the incidence of postoperative cognitive dysfunction (POCD) in eldedy patients after general anesthesia. Methods Forty ASA Ⅰ-Ⅲ patients of both sexes aged 65-79 yr weighing 48-76 kg undergoing elective non-cardiac surgery under general anesthesia were studied.Anesthesia was induced with midazolam,fentanyl,etomidate and succinylcholine and maintained with continuous iv infusion of propofol,remifentanil,isoflurane inhalation and intermittent iv boluses of vecuronium.The right internal jugular vein was cannulated with a catheter which was advanced cephalad until jugular bulb.The jugular bulb venous blood samples were taken before (T0,baseline),at the end of (T1) and at 24,48 and 72h(T2-4) after operation for measurement of plasma concentrations of glutamate (Glu),aspartate (Asp) and glycine (Gly) by RP-HPLC.The cognitive function was evaluated by mini-mental state examination (MMSE) at T0 and T4.Results Eleven of the 40 patients developed POCD (28%).The plasma Gh,Asp and Gly concentrations were significantly increased after operation as compared with the baseline values in POCD patients and were significantly higher than in non-POCD patients.The plasma concentrations of Glu and Asp were negatively correlated with MMSE score(Glu:r=-0.86.P<0.01;Asp:r=-0.99,P<0.01).Conclusion Elderly patients may develop POCD after operation performed under general anesthesia through increase in intracranial EAA levels. Key words: Excitatory amino acids; Aged; Postoperative complications; Cognition disorder; Anesthesia,general

Total Intravenous Anesthesia (TIVA) in an Infant with Werdnig-Hoffmann Disease. Case Report

Werdnig-Hoffmann disease is the most common cause of hypotonia in infants and its prognosis is worse if it is present shortly after delivery. Symmetrical muscular weakness, areflexia, and fasciculations of the tongue are characteristic. The majority of the infants die before two years of age as a consequence of respiratory failure. The present report presents a case in which total intravenous anesthesia was used. This is a 1 year old white female weighing 10 kg, physical status ASA III, with Werdnig-Hoffmann disease diagnosed at two months of age. The patient was a candidate for open gastrostomy, fundus gastroplication, and tracheostomy. After venoclysis, the patient was monitored with cardioscope, non-invasive blood pressure, pulse oximeter, precordial stethoscope, and rectal temperature. She was oxygenated and, after bolus administration of atropine (0.3 mg), boluses of remifentanil (20 microg) and propofol (30 mg) were administered for anesthetic induction. After tracheal intubation, she was ventilated with manual controlled system without CO(2) absorber, Baraka (Mapleson D system), FGF of 4 L.min(-1), and FiO(2) 0.5 (O(2)/N(2)O). Anesthesia was maintained with continuous manual infusion of propofol, 250 microg x kg(-1) x min(-1), and remifentanil, 0.3 microg x kg(-1) x min(-1). The surgery lasted 150 minutes. The patient regained consciousness 8 minutes after the end of the infusion, ventilating spontaneously. Two hours later, she was transferred to the pediatric unit, being discharged from the hospital on the fourth postoperative day. The choice of anesthetic technique gives priority to the safety associated with the familiarity of handling available drugs. In children with neuromuscular diseases, due to the extremely short duration, total intravenous anesthesia with remifentanil and propofol in infusion systems can have a favorable influence on disease evolution.

Comparative study of effective-site target controlled infusion with standard bolus induction of propofol for laryngeal mask airway insertion

Abstract Several studies demonstrated induction of anesthesia with different plasma target-controlled infusion (TCI) of propofol for LMA insertion. However, there has been no study to compare the standard bolus propofol induction with the effective site TCI for LMA insertion. Objective: Compare the efficacy of induction of anesthesia with propofol for LMA insertion between the effective-site TCI, using 6 μg/mL, and the standard bolus propofol dose of 2.5 mg/kg in elective surgical patients. Methods: A randomized, prospective, single-blinded, clinical study was used for this study. Seventy-eight unpremedicated patients, American Society of Anesthesiologists (ASA) physical status I and II undergoing elective surgical procedure were randomly allocated between two groups. Group 1 received the standard bolus propofol dose of 2.5 mg/kg. Group 2 received effective site TCI (Schnider model) dose of 6 μg/mL for LMA insertion. The hemodynamics and anesthetic depth (Bispectral index score) were monitored and recorded during and immediately after LMA insertion. The number of insertion attempted, insertion quality score, induction time, and propofol doses used were recorded and compared between groups. Results: The success rate of first insertion attempt was equal in both groups (92.3%). There was no significant hemodynamic response difference between the groups during pre-induction, induction, insertion, and post insertion period. The BIS score was significantly lower during post insertion period in group 1 (51.4+11.0) than group 2 (58.4+3.2) (p=0.013). The propofol doses in group 2 were significantly lower than in group 1 (110.6+14.8 vs. 153.5+21.5) (p &lt;0.001). Patients in group 2 required significantly more induction time than group 1 (146.9+42.3 vs. 103.4+33.6 (p &lt;0.001). Conclusion: Propofol induction with TCI provided equal success rate as compared with standard bolus propofol induction for LMA insertion and insertion quality score. TCI significantly lowered the propofol consumption when compared with the standard 2.5 mg/kg propofol dose.

A novel technique in placing a Fogarty catheter in the upper limb of a Montgomery T-tube for a patient undergoing tracheal resection

To the Editor: A number of ventilation strategies exist for patients with Montgomery T-tubes during tracheal resection. We describe a novel technique with antegrade passage of a Fogarty catheter through the mouth, guided by a suture to the upper limb of the T-tube. Written consent for publication of this article was obtained from the patient. A 59-yr-old female patient (weight 89 kg, height 173 cm) diagnosed with idiopathic tracheal stenosis was scheduled to undergo tracheal resection. A computed tomography scan of her neck showed tracheal stenosis 1.3 cm in length located 1.5 cm below the glottis. In the operating room, standard monitoring was applied and the patient was anesthetized with remifentanil, propofol bolus and infusion, and rocuronium. The patient’s lungs were ventilated with 100% oxygen with bag and mask for two minutes. Serial rigid bronchoscopies were performed up to 8.0 mm, and a size 6.5 mm (internal diameter) armoured tracheal tube was inserted into the trachea under direct laryngoscopy. The surgeons proceeded with a 3-cm cricotracheal resection with thyrotracheal anastomosis. During the resection, the patient’s lungs were ventilated with an armoured tracheal tube attached to the distal trachea just below the second ring. Later, during the anastomosis, the armoured tracheal tube was removed from the distal trachea. A size 11 mm (outer diameter) Montgomery T-tube (LT-511) (E. Benson Hood Laboratories, Inc, Pembroke, MA, USA) was inserted into the trachea to serve as a stent, and thyrotracheal anastomosis was performed. As positive pressure ventilation of the lungs was required until the anastomosis was fully completed, a 15-mm connector was attached to the extratracheal limb of the T-tube to connect the ventilation circuit. In order to seal off the supraglottic leak through the upper limb of the T-tube, the following novel technique was used to pass a Fogarty catheter into the upper limb of the T-tube: Immediately after incision of the trachea, a suture was attached to the Murphy’s eye of the tracheal tube. The tracheal tube was partially withdrawn during the tracheal resection; then, as the surgeons were ready to insert the T-tube, the tracheal tube was completely withdrawn and the suture to the Murphy’s eye was cut. Next, the proximal end of the suture was tied to the tip of the Fogarty occlusion catheter (Model 62080814F) (Edwards Lifesciences LLC, Irvine, CA, USA) just distal to the balloon. The distal end of the suture was pulled slowly by the surgeon, and the Fogarty catheter was advanced through the mouth and glottis and positioned in the upper limb of the T-tube under direct visual guidance (Figure 1). Then, the balloon of the Fogarty catheter was inflated to provide an occlusive seal. A 15-mm connector was inserted into the extratracheal limb and positive pressure ventilation was commenced. At the end of surgery, inhalational anesthesia was discontinued and muscle relaxation was reversed. The patient awoke and breathed spontaneously. The 15-mm connector was disconnected from the extratracheal limb of the T-tube, and an oxygen mask was placed over both the extratracheal limb of the T-tube and the patient’s face. D. T. Wong, MD (&) Toronto Western Hospital, University of Toronto, Toronto, ON, Canada e-mail: david.wong@uhn.on.ca

Cerebral and Systemic Hemodynamic Effects of Intravenous Bolus Administration of Propofol in Neonates

Objectives: To assess variability of systemic hemodynamics and its covariates following bolus propofol administration in (pre)term neonates, and to analyze the effect of propofol on cerebral tissue oxygenation index (TOI) and fractional tissue oxygen extraction measured by near-infrared spectroscopy. Methods: In (pre)term neonates, we recorded mean arterial blood pressure (MABP), saturation (SaO₂), heart rate (HR) and TOI from 5 min before up to 60 min after intravenous bolus propofol (3 mg kg^–1) administration during elective chest tube removal. Covariate analysis included postmenstrual age (PMA ≤ or >37 weeks), postnatal age (PNA ≤ or >10 days), comedication (fentanyl +/– midazolam) and congenital cardiopathy (yes/no). Fractional tissue oxygen extraction was calculated as (SaO₂ – TOI)/SaO₂. Results: Twenty recordings in 19 neonates were assessed. Following propofol administration, an abrupt, minor decrease in HR and SaO₂ was seen with fast recovery, while MABP decreased up to 1 h. TOI decreased during the first 3 min, reflecting an imbalance between cerebral oxygen delivery and demand. Despite sustained decrease in MABP, TOI then returned to baseline, suggesting a better balance between oxygen delivery and demand. PNA ≤10 days, comedication and absence of cardiopathy were associated with more subtle decreases in cerebral oxygenation and faster recovery. Conclusions: Propofol-induced decrease in HR, SaO₂ and cerebral oxygenation is short lasting while a decrease in MABP is observed up to 60 min. The variability in the effects of propofol is influenced by PNA, comedication or cardiopathy. Near-infrared spectroscopy can be used to assess hemodynamic effects of hypnotics on the cerebral oxygenation.

Single dose of preoperative analgesia with gabapentin (600 mg) is safe and effective in monitored anesthesia care for nasal surgery

This study was aimed to compare the intraoperative sedative and perioperative analgesic drug requirements and the incidences of postoperative side effects on the patients who received preoperative gabapentin or placebo. Sixty patients undergoing nasal septal or nasal sinus surgery were included. The patients received either 600 mg gabapentin (Group G) or placebo (Group P) orally, 1 h before surgery. The scores for sedation and pain were recorded at 5, 15, 30, 45 and 60 min, intraoperatively and at 30 min, 1, 2, 4, 6, 9, 12, 16, 20, 24 h, postoperatively. Sedation was achieved with an IV bolus of propofol and continuous infusion of remifentanil. There were significant differences between gabapentin and placebo groups with regard to total consumptions of remifentanil (171.42 + or - 68 vs. 219.17 + or - 95 microg, respectively; P = 0.033) and propofol (59.45 + or - 36.08 vs. 104.14 + or - 54.98 mg, respectively; P = 0.001). Group G patients had significantly lower intraoperative VAS scores at all time points (P < 0.05). The anxiety score of Group G was better at all times (P < 0.05). All postoperative pain scores were lower in the Group G (P < 0.05). Time to first request for analgesic was 12.7 + or - 2.3 h in Group G, and 7.8 2.1 h in Group P (P < 0.0001). Total consumption of lornoxicam was lower in Group G (P < 0.004). We concluded that monitored anesthesia care combined with preoperative analgesia with a low dose of (600 mg) oral gabapentin is an efficient option with tolerable side effects for patients undergoing ear, nose and throat ambulatory surgery.

Cardiac electrophysiological effects of remifentanil: study in a closed-chest porcine model

Remifentanil has been implicated as causing intraoperative bradyarrhythmias, but little information is available regarding its cardiac electrophysiological effects. Thus, we evaluated the cardiac electrophysiological properties before and after remifentanil in a closed-chest porcine model. Eighteen Landrace-Large pigs were premedicated with ketamine and anaesthetized with propofol (4.5 mg kg(-1) bolus followed by 13 mg kg(-1) h(-1)). After instrumentation, an electrophysiological evaluation was performed under propofol and repeated after remifentanil (bolus of 1 microg kg(-1), followed by an infusion of 0.5 microg kg(-1) min(-1)). We evaluated sinus node function [sinus node recovery time (SNRT) and sinoatrial conduction time (SACT)], atrioventricular (AV) nodal function [AH intervals during sinus rhythm (SR) and atrial pacing, Wenckebach cycle length (WCL), and effective refractory periods (ERP)], atrial, His-Purkinje, and ventricular conduction and refractoriness. Significant changes between 'propofol protocol' and 'propofol+remifentanil protocol' were evaluated. Remifentanil caused a significant increase in sinus cycle length (21%, P=0.001) and a significant prolongation of SNRT (43%, P=0.001), corrected SNRT (136%, P=0.003), SACT (40%, P=0.005), AH interval during SR (17%, P=0.02), AH interval during atrial pacing (25%, P=0.01), and ventricular ERP (12%, P=0.004). There was a tendency towards a prolongation of WCL and AV nodal refractoriness. Similar significant changes were observed in a reference group of seven animals in which sevoflurane was used instead of propofol. No significant changes were observed in atrial parameters, His-Purkinje function, parameters of intraventricular conduction, and QT intervals. Remifentanil depresses sinus node function and most parameters of AV nodal function. This contributes to an explanation for clinical observations of remifentanil-related severe bradyarrhythmias.

Ventricular rhythm in atrial fibrillation under anaesthetic infusion with propofol

Changes in patients' autonomic tone and specific pharmacologic interventions may modify the ventricular response (actual heart rate) during atrial fibrillation (AF). Hypnotic agents such as propofol may modify autonomic balance as they promote a sedative state. It has been shown that propofol slightly slows atrial fibrillatory activity, but the net global effect on the ventricular response remains unknown. We aimed to evaluate in patients in AF the effect of a propofol bolus on the ventricular rate and regularity at ECG. We analysed the possible relation with local atrial fibrillatory activities, as ratios between atrial and ventricular rates (AVRs), analysing atrial activity from intracardiac electrograms at the free wall of the right and left atria and at the interatrial septum. We compared data at the baseline and after complete hypnosis. Propofol was associated with a more homogeneous ventricular response and lower AVR values at the interatrial septum.

Low-Dose Propofol Sedation for Diagnostic Esophagogastroduodenoscopy: Results in 10,662 Adults

The use of propofol sedation during endoscopic procedures has increased in recent years. The aim of this study was to evaluate the safety and effectiveness of nurse-administered low-dose propofol sedation for diagnostic esophagogastroduodenoscopy (EGD). We prospectively assessed the outcome and complications of low-dose bolus propofol for endoscopic sedation for diagnostic EGD. Propofol was administered by bolus injection, with a standard protocol of 40 mg for patients <70 years old, 30 mg for patients 70-89 years old, and 20 mg for patients 90 years or older. When required for adequate sedation, additional doses were given, to a maximum of 120 mg. The primary outcome measure was respiratory depression, defined as oxygen desaturation (SpO(2) <90%) that continued for more than 20 s. Secondary measures included successful procedures, full recovery within 60 min of the procedure, and complications. All procedures were successful; 8,431 of 10,662 patients (79.1%) completed diagnostic EGD with a single bolus of propofol. Only 0.26% (28 patients) required transient supplemental oxygen supply; neither mask ventilation nor endotracheal intubation was required. Full recovery occurred in 99.9% of patients 60 min after the procedure. Men and younger patients required significantly higher doses of propofol than did the women and older patients (men vs. women, 46.5+/-19 vs. 42.7+/-15 mg, P=0.0008; age 40-49 vs. age 50-59, 51.5+/-16 vs. 46.3+/-13 mg, P<0.0001). Of the 400 patients, 368 (92%) wanted to drive home or to their offices, and all did so without incident. A total of 99% were willing to repeat the same procedure again. Low-dose nurse-administered propofol sedation is safe and practical for diagnostic EGD.

The feasibility of recording blink reflexes under general anesthesia

Until now, there have been no reports on eliciting the blink reflex (BR) during anesthesia at a depth compatible with surgery. We introduce a novel method for eliciting the R1 component of the BR under inhalation or total intravenous anesthesia by using a short train of four to seven stimuli applied over the supraorbital nerve. Recording is done from the ipsilateral orbicularis oculi muscle. We set out to record the BR in 27 patients (age 1-78 years) without involvement of the facial nerve, trigeminal nerve, or brainstem. The BR could not be recorded in only 4 patients (recordability: 86.2%). All patients received at least one bolus of propofol while in surgery. Using this method, the BR was recorded on 4 awake healthy subjects. Boluses of propofol and muscle relaxants should be avoided in order to successfully record the responses. BR recording is feasible in patients under general anesthesia by using this novel technique. Muscle Nerve 39: 642-646, 2009.

Identification of predictors of post‐ictal delirium after electroconvulsive therapy

Although electroconvulsive therapy (ECT) often causes post-ictal delirium (PID), to date, the specific risk factors of PID have not been described. The purpose of the present study was therefore to elucidate the predictors of PID via identification of the characteristics of patients with PID. ECT was conducted in 50 patients and all patients underwent more than four sessions. A sine wave or a brief-pulse square wave ECT instrument was used. After convulsions the patients' PID was monitored for 30 min. The patients were allocated into four groups based on PID severity (none, mild, moderate or severe PID). Variables, including age, gender, duration of illness, diagnosis, clinical features (psychotic or catatonic features) and stimulus waveform (sine or brief pulse square waveform), were analyzed. Moderate to severe PID developed during the ECT sessions in 18 patients (36%). Most patients with severe delirium were successfully treated with i.v. bolus of propofol (1-2 mg/kg). Although the incidence of PID was 24% in patients without catatonic features, the incidence in patients with catatonic features was extremely high (88%; P < 0.001). Multiple regression analyses showed that the severity of PID correlated significantly with the presence of catatonic features (beta = 0.428, P < 0.01). The presence of catatonic features before ECT is a predictor of PID. Propofol is useful for the treatment of PID.

The use of boluses of propofol for the management of severe tetanus in a child

Tetanus is endemic in many developing countries. Although propofol has been proposed for sedation in tetanus, the routine use of this drug has not been clearly documented in published reports. A few studies have reported its beneficial effects but no randomized studies are available. We describe the case of a five-year-old boy who presented with severe tetanus in East Africa. The antispastic therapy consisted of benzodiazepine infusion with the addition of titrated boluses of propofol. Intubation and mechanical ventilation were avoided.

Acute Airway Obstruction Caused by the New Single Use Laryngeal Mask Airway Supreme™

Acute Airway Obstruction Caused by the New Single Use Laryngeal Mask Airway Supreme™

Effect of propofol on twitch diaphragmatic pressure evoked by cervical magnetic stimulation in patients

BackgroundSeveral studies have demonstrated the inhibitory effect of propofol on diaphragmatic contractility in laboratory animals, but there have been few studies in humans. We have investigated the effect of a single bolus injection of propofol on twitch diaphragmatic pressure (TwPdi) evoked by cervical supramaximal magnetic stimulation, and its impact on diaphragmatic contractility. MethodsIn 16 patients scheduled for elective operation, TwPdi was evoked bilaterally at the cervical phrenic nerves with supramaximal magnetic stimulations using a 140 mm diameter magnetic coil. Changes of TwPdi were monitored dynamically before and during general anaesthesia induced by single bolus of propofol 2 mg kg −1. During the study, all patients breathed 100% oxygen by a face mask, maintaining Spo2 ≥99% and Pe′co2 4.6–5.2 kPa. ResultsTwPdi declined after administration of propofol with gradual recovery. Compared with baseline [20.6 (6.0) cm H2O], TwPdi decreased by 23.3% (P<0.001) to [15.8 (6.4) cm H2O]. When the patients regained awareness, TwPdi returned to [19.1 (6.1) cm H2O], close to baseline (P=0.063). The time from starting the propofol infusion to the lowest TwPdi was [240 (86) s]. Total time course of stimulation lasted [363 (89) s]. ConclusionsA single bolus propofol depressed TwPdi evoked by cervical magnetic stimulation, demonstrating inhibitory effects of propofol on diaphragmatic contractility in patients during general anaesthesia.