NIR-II nanoprobes for investigating the glymphatic system function under anesthesia and stroke injury.

The glymphatic system plays an important role in the transportation of cerebrospinal fluid (CSF) and the clearance of metabolite waste in brain. However, current imaging modalities for studying the glymphatic system are limited. Herein, we apply NIR-II nanoprobes with non-invasive and high-contrast advantages to comprehensively explore the function of glymphatic system in mice under anesthesia and cerebral ischemia-reperfusion injury conditions. Our results show that the supplement drug dexmedetomidine (Dex) enhances CSF influx in the brain, decreases its outflow to mandibular lymph nodes, and leads to significant differences in CSF accumulation pattern in the spine compared to isoflurane (ISO) alone, while both ISO and Dex do not affect the clearance of tracer-filled CSF into blood circulation. Notably, we confirm the compromised glymphatic function after cerebral ischemia-reperfusion injury, leading to impaired glymphatic influx and reduced glymphatic efflux. This technique has great potential to elucidate the underlying mechanisms between the glymphatic system and central nervous system diseases.

Effects of Volatile Anesthetics versus Ketamine on Blood-Brain Barrier Permeability via Lipid-Mediated Alterations of Endothelial Cell Membranes.

The purpose of this study was to investigate the effects of the volatile anesthetic agents isoflurane and sevoflurane, at clinically relevant concentrations, on the fluidity of lipid membranes and permeability of the blood-brain barrier (BBB). We analyzed the in vitro effects of isoflurane or ketamine using erythrocyte ghosts (sodium fluorescein permeability), monolayers of brain microvascular endothelial cells ([13C]sucrose and fluorescein permeability), or liposomes (fluorescence anisotropy). Additionally, we determined the effects of 30-minute exposure of mice to isoflurane on the brain tight junction proteins. Finally, we investigated in vivo brain uptake of [13C]mannitol and [13C]sucrose after intravenous administration in mice under anesthesia with isoflurane, sevoflurane, or ketamine/xylazine in addition to the awake condition. Isoflurane at 1-mM and 5-mM concentrations increased fluorescein efflux from the erythrocyte ghosts in a concentration-dependent manner. Similarly, in endothelial cell monolayers exposed to 3% (v/v) isoflurane, permeability coefficients rose by about 25% for fluorescein and 40% for [13C]sucrose, whereas transendothelial resistance and cell viability remained unaffected. Although isoflurane caused a significant decrease in liposomes anisotropy values, ketamine/xylazine did not show any effects. Brain uptake clearance (apparent Kin) of the passive permeability markers in vivo in mice approximately doubled under isoflurane or sevoflurane anesthesia compared with either ketamine/xylazine anesthesia or the awake condition. In vivo exposure of mice to isoflurane did not change any of the brain tight junction proteins. Our data support membrane permeabilization rather than loosening of intercellular tight junctions as an underlying mechanism for increased permeability of the endothelial cell monolayers and the BBB in vivo. SIGNIFICANCE STATEMENT: The blood-brain barrier controls the entry of endogenous substances and xenobiotics from the circulation into the central nervous system. Volatile anesthetic agents like isoflurane alter the lipid structure of cell membranes, transiently facilitating the brain uptake of otherwise poorly permeable, hydrophilic small molecules. Clinical implications may arise when potentially neurotoxic drugs gain enhanced access to the central nervous system under inhalational anesthetics.

Influence of general anaesthesia on the intravenous acetaminophen pharmacokinetics in Beagle dogs.

OBJECTIVE: To determine if general anaesthesia influences the intravenous (IV) pharmacokinetics (PK) of acetaminophen in dogs. STUDY DESIGN: Prospective, crossover, randomized experimental study. ANIMALS: A group of nine healthy Beagle dogs. METHODS: Acetaminophen PK were determined in conscious and anaesthetized dogs on two separate occasions. Blood samples were collected before, and at 5, 10, 15, 30, 45, 60 and 90 minutes and 2, 3, 4, 6, 8, 12 and 24 hours after 20 mg kg-1 IV acetaminophen administration. Haematocrit, total proteins, albumin, alanine aminotransferase, aspartate aminotransferase, urea and creatinine were determined at baseline and 24 hours after acetaminophen. The anaesthetized group underwent general anaesthesia (90 minutes) for dental cleaning. After the administration of dexmedetomidine (3 µg kg-1) intramuscularly, anaesthesia was induced with propofol (2-3 mg kg-1) IV, followed by acetaminophen administration. Anaesthesia was maintained with isoflurane in 50% oxygen (Fe'Iso 1.3-1.5%). Dogs were mechanically ventilated. Plasma concentrations were analysed with high-performance liquid chromatography. PK analysis was undertaken using compartmental modelling. A Wilcoxon test was used to compare PK data between groups, and clinical laboratory values between groups, and before versus 24 hours after acetaminophen administration. Data are presented as median and range (p < 0.05). RESULTS: A two-compartmental model best described time-concentration profiles of acetaminophen. No significant differences were found for volume of distribution values 1.41 (0.94-3.65) and 1.72 (0.89-2.60) L kg-1, clearance values 1.52 (0.71-2.30) and 1.60 (0.91-1.78) L kg-1 hour-1 or terminal elimination half-life values 2.45 (1.45-8.71) and 3.57 (1.96-6.35) hours between conscious and anaesthetized dogs, respectively. Clinical laboratory variables were within normal range. No adverse effects were recorded. CONCLUSIONS AND CLINICAL RELEVANCE: IV acetaminophen PK in healthy Beagle dogs were unaffected by general anaesthesia under the study conditions. Further studies are necessary to evaluate the PK in different clinical contexts.

ISOFLURANE ANESTHESIA IN THE MADAGASCAR HISSING COCKROACH (GROMPHADORHINA PORTENTOSA).

This study investigated the efficacy of isoflurane in Madagascar hissing cockroaches (Gromphadorhina portentosa). Cockroaches (n = 12) were placed in a 2-L anesthesia chamber with isoflurane initiated at 5% at 2 L/m. Movement of antennae, mandibles, and legs and righting reflex were assessed, with full induction achieved when all responses had ceased for 2 m. Cockroach movement became ataxic on average (±SD) 3.5 ± 0.9 m after isoflurane treatment, and induction occurred on average 18.7 ± 4.4 m after treatment. Loss of righting reflex was the most consistent indication of full induction. Cockroaches fully recovered on average 16.2 ± 5.6 m after removal of isoflurane inhalant. Induction was uneventful, and no mortality or obvious morbidity was observed in treated cockroaches up to 30 d posttreatment. The authors conclude that the use of inhalant isoflurane is both safe and effective for anesthesia of Madagascar hissing cockroaches.

A Comparison of the Arterial Blood Concentration of Isoflurane During Cardiopulmonary Bypass Between 2 Polypropylene Oxygenators.

OBJECTIVE: The primary objective was to compare arterial blood concentration of isoflurane during cardiopulmonary bypass (CPB) between 2 polypropylene oxygenators of different designs. Secondary objectives were to compare levels of Bispectral Index Score (BIS) during CPB between the 2 oxygenators and to examine the relationships between oxygenator exhaust and arterial blood concentrations of isoflurane and BIS. DESIGN: Single, blinded, randomized control trial. SETTING: Teaching hospital. PARTICIPANTS: Twenty-five patients undergoing cardiac surgery with CPB. INTERVENTIONS: Subjects were randomly assigned (1:1) to Inspire 8F (Sorin) or Affinity Fusion (Medtronic) oxygenators. MEASUREMENTS AND MAIN RESULTS: The mean arterial blood concentration in the Inspire 8F (Sorin) group was 59 (standard deviation [SD] 23) µg/mL, compared with 53 (SD 17) µg/mL in the Affinity Fusion (Medtronic) group with a nonsignificant mean difference of 6 (95% confidence interval = -11, 22) µg/mL (t[23] = 0.676, p = 0.50). No significant difference in BIS was found between the groups (p = 0.896). Moderate and strong, negative correlations respectively, were found between arterial and oxygenator exhaust correlations and BIS (r = -0.472, p < 0.05; r = -0.812, p < 0.001). A strong, positive correlation was found between arterial and exhaust isoflurane concentration (r = 0.810, p < 0.0005). CONCLUSIONS: No significant difference in arterial blood concentration of isoflurane or BIS was found between the Inspire 8F (Sorin) and Affinity Fusion (Medtronic) oxygenators. A significant positive correlation was found between arterial blood and oxygenator exhaust concentrations of isoflurane, as well as significant negative correlations between both arterial and oxygenator exhaust concentrations of isoflurane and BIS.

Comparison of recovery in pediatric patients: a retrospective study.

OBJECTIVE: The recovery after general anesthesia is influenced by the choice of inhalational agent. Stimulations might make patient's agitate. However, the recovery using no touch technique might be safer. In this study, we compared the recovery time, awakening end-tidal concentration, and respiratory complications among inhalational anesthetics in pediatric patients using no touch technique, retrospectively. MATERIAL AND METHODS: The subjects were pediatric patients aged 3 months to 11 years under general anesthesia using sevoflurane, isoflurane, or desflurane. Background, awakening end-tidal concentration, respiratory complications, the time of eye open, body movement, and extubation were recorded. RESULTS: A total of 170 patients were included in the study. There were no respiratory complications during emergence. Awakening end-tidal concentration in desflurane was 0.98%, sevoflurane (0.39%), and isoflurane (0.25%). In patients received desflurane, the time of body movement, eye open, and extubation were significantly shorter than patients who received other anesthetics (p < 0.05). CONCLUSIONS: The recovery from desflurane was significantly shorter among three inhalational anesthetics with no touch technique. In addition, no airway-related complication occurred. CLINICAL RELEVANCE: The recovery from desflurane might be useful to predict emergence by end-tidal inhalational concentration.

Low-flow anaesthesia with a fixed fresh gas flow rate.

During the wash-in period in low flow anaesthesia (LFA), high fresh gas flow is used to achieve the desired agent concentration. In this study, we aimed to evaluate the safety of fixed 1 L/min fresh gas flow desflurane anaesthesia in both the wash-in and maintenance periods in patients including the obese ones. 104 patients undergoing surgery under general anaesthesia were included. After endotracheal intubation, fresh gas flow was reduced to 1 L/min and the desflurane vaporizer was set at 18%. The time from opening the vaporizer to end-tidal desflurane concentration reaching 0.7 MAC was recorded (MAC 0.7 time). Throughout the surgery, hemodynamic variables, FIO2, MAC and BIS values were observed. MAC 0.7 time, BIS and MAC values at the start of surgery, number of adjustments in vaporizer settings, desflurane consumption were recorded. The average MAC 0.7 time was 2.9 ± 0.5 min. MAC and BIS values at the start of the surgery were 0.7 (0.6-0.8) and 39 ± 8.5 respectively. No individual patient had a BIS value above 60 throughout the surgery. Hemodynamic variables were stable and FIO2 did not fall below 30% in any patient. The number of adjustments in vaporizer settings was 56. Average desflurane consumption was 0.33 ± 0.05 mL/min. We demonstrated that LFA without use of initial high fresh gas flow during the wash-in period is an effective, safe and economic method which is easy to perform.

Isoflurane alone versus small dose propofol with isoflurane for removal of laryngeal mask airway in children-a randomized controlled trial.

OBJECTIVE: To compare the safety of laryngeal mask airway removal using two different deep anaesthesia techniques in paediatric patients. METHODS: The Randomized Control Trial was conducted at Aga Khan University Hospital, Karachi, from April 2012 to November 2013, and comprised patients aged 2-10 years scheduled for infraumbilical surgeries. Anaesthesia was induced with sevoflurane and later it was maintained by is oflurane, oxygen and nitrous oxide. The laryngeal mask airway was removed in the intervention group-I at 0.4 minimum alveolar concentration of isoflurane with propofol 1mg/kg. In the control group-II, it was removed at 1.2 minimum alveolar concentration of isoflurane alone. SPSS 19 was used for data analysis. RESULTS: Of the 50 patients, there were 25(50%) in each of the two groups. Overall, there were 46(92%) males and 4(8%) females. Incidence of airway obstruction and teeth clenching was significantly higher in group-II (p<0.05 each). Emergence duration was also significantly increased in group-II compared to group-I (p=0.001). The Post-Anaesthesia Care Unit stay timing was not significantly different between the groups (p=0.74). CONCLUSIONS: Laryngeal mask airway removal under deep anaesthetic technique of low-dose propofol with isoflurane was found to be associated with minimal adverse airway events than isoflurane alone in paediatric patients.

Evaluation of a novel waste anaesthetic gas scavenger device for use during recovery from anaesthesia.

Volatile anaesthetic agents are a potential occupational health hazard to theatre and recovery staff. Operating theatres and anaesthetic rooms are required to be equipped with scavenging systems, but recovery units often are not. We compared exhaled, spectrophotometric sevoflurane and desflurane concentrations 15 cm from the mouth ('patient breathing zone') and 91 cm laterally to the patient ('nurse work zone') in 120 patients after tracheal extubation who were consecutively allocated to either ISO-Gard mask oxygen/scavenging or standard oxygen mask, 0 min, 10 min and 20 min after arrival in the theatre recovery unit. Median (IQR [range]) duration of anaesthesia was similar between groups (control 76 (44-119 [15-484]) min vs. study group 90 (64-130 [15-390]) min, p = 0.136). Using the ISO-Gard mask, the 20-min mean patient breathing zone and nurse work zone exhaled anaesthetic levels were ~ 90% and 78% lower than those recorded in the control group, respectively, and were within the recommended 2 ppm maximum environmental exposure limit in the patient breathing zone of 53 out of 60 (88%) and the nurse work zone of all 60 (100%) patients on first measurement in the recovery room (vs. 10 out of 60 (17%) and 40 out of 60 (67%) in the control group). Our study indicates that the ISO-Gard oxygen/scavenging mask reduces the level of exhaled sevoflurane and desflurane below recommended maximum exposure limits near > 85% of extubated patients within ~ 20 s of application in the recovery unit after surgery. We encourage the use of this mask to minimise the occupational exposure of recovery staff to exhaled volatile agents.

ANESTHESIA OF AQUARIUM-HOUSED WALRUS ( ODOBENUS ROSMARUS): A CASE SERIES.

Walruses are a challenging species to anesthetize as a result of their large mass, limited access for drug delivery, unique physiology, and small number of reports describing anesthetic procedures. Three aquarium-housed walruses ( Odobenus rosmarus) ranging in age from 3 to 11 yr old (344-1,000 kg) were anesthetized for dental or ophthalmic surgical procedures, with one animal anesthetized twice and one anesthetized three times. Preanesthetic medication was with intramuscular midazolam (0.1-0.2 mg/kg) and meperidine (2-3 mg/kg). A catheter was placed in the extradural intravertebral vein, and anesthesia was induced with propofol to effect. Orotracheal intubation was performed and anesthesia maintained with isoflurane in oxygen using a circle breathing system connected to a ventilator. Intermittent positive pressure ventilation was used in all procedures. For the ophthalmic surgery, the neuromuscular blocking agent, cisatracurium, was given intravenously to provide a central eye and optimal surgical conditions. The neuromuscular block was antagonized with edrophonium. Total anesthesia times ranged from 1.5 to 6 hr. Midazolam and meperidine were antagonized with flumazenil and naltrexone, respectively, in five of six cases. Nonsteroidal anti-inflammatory agents were provided for analgesia. Recoveries were calm and uneventful. The described anesthetic protocols and case management were successful under the conditions encountered.

Tunable Porous Coordination Polymers for the Capture, Recovery and Storage of Inhalation Anesthetics.

The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of ZnII centres and dianionic ligands that contain a phenolate and a carboxylate group at opposite ends. All three framework materials are able to adsorb N2 O, Xe and isoflurane. Whereas the framework with the widest channels is able to adsorb large quantities of the various guests from the gas phase, the frameworks with the narrower channels have superior binding enthalpies and exhibit higher levels of retention. The use of ligands in which substituents are bound to the aromatic rings of the bridging ligands offers great scope for tuning the adsorption properties of the framework materials.

Use of Volatile Anesthetic Agent in Extracorporeal Circuit as a Cause of Break in Polycarbonate Connector-Lessons Learnt.

Mishaps, near misses, and lethal incidents are known to occur during cardiopulmonary bypass. We share one such rare case of break in polycarbonate connector because of the use of isoflurane in extracorporeal circuit and its successful management.

Postoperative environmental anesthetic vapour concentrations following removal of the airway device in the operating room versus the postanesthesia care unit.

PURPOSE: This study was designed to compare waste anesthetic gas (WAG) concentrations within patients' breathing zones after removal of the patient's airway device in the postanesthesia care unit (PACU) vs in the operating room (OR). METHODS: Following Research Ethics Board approval and patient consent, we recruited patients undergoing surgery who received volatile anesthesia via an endotracheal tube or supraglottic airway. Patients had their airway device removed in the OR or in the PACU depending on the attending anesthesiologist's preference. Upon the patient's arrival in the PACU, concentrations of exhaled sevoflurane and desflurane were measured at their breathing zone (i.e., 15 cm from the patient's mouth and nose) using a single-beam infrared spectrophotometer. RESULTS: Seventy patients were recruited during the five-month study period. The median [interquartile range] WAG levels in the patients' breathing zones were higher when their airway devices were removed in the PACU vs in the OR. The WAG levels for sevoflurane were 0.7 [0.4-1.1] parts per million (ppm) vs 0.5 [0.4-0.7] ppm, respectively; median difference, 0.3; 95% confidence interval (CI), 0.1 to 0.6; P = 0.04. The WAG levels for desflurane were 2.4 [1.2-3.4] ppm vs 4.1 [2.5-5.2] ppm, respectively; median difference, 1.5; 95% CI, 0.3 to 2.7; P = 0.04. CONCLUSIONS: After a volatile-based anesthetic, our results suggest that removal of the airway device in the PACU vs in the OR increases the amount of waste anesthetic gas in a patient's breathing zone and thus potentially in the PACU nurse's working zone.

Evaluation and control of isoflurane during experimental dental procedures on rodents.

The purpose of this study was to assess exposures to isoflurane to employees performing an experimental dental procedure on rodents. Isoflurane was used as an anesthetic for rodents during injections and placement of dental apparatus into the mouth. We collected eight full-shift samples using passive badges over a three-week period. The procedure was performed once a week for approximately 45 min each day. Results showed that employees were being exposed to isoflurane above the National Institute for Occupational Safety and Health recommended exposure level for halogenated anesthetic gases of two parts per million. The employer installed a ventilation system in the procedure room after the initial sampling and results. We collected 12 full-shift samples after the ventilation system was in place. Results showed an approximate 86% decrease in isoflurane concentration.

General Anesthesia for a Patient With Pelizaeus-Merzbacher Disease.

We report the successful management of general anesthesia for a patient with Pelizaeus-Merzbacher disease (PMD). PMD is one of a group of progressive, degenerative disorders of the cerebral white matter. The typical clinical manifestations of PMD include psychomotor retardation, nystagmus, abnormal muscle tone, seizures, and cognitive impairment. General anesthesia for a patient with PMD may be difficult mainly because of seizures and airway complications related to poor pharyngeal muscle control. In addition, the possibility of exacerbation of spasticity should be considered. A 20-year-old man with PMD required removal of impacted wisdom teeth under general anesthesia. General anesthesia was induced with thiamylal, fentanyl, and desflurane. Anesthesia was maintained with desflurane and continuous intravenous remifentanil under bispectral index and train-of-4 monitoring. Anesthesia lasted 1 hour 20 minutes and was completed uneventfully. Airway complications, seizures, and exacerbation of spasticity did not occur postoperatively. Preoperatively, our patient had no history of epilepsy attacks or aspiration pneumonia, and no clinical symptoms of gastroesophageal reflux disease. Therefore, exacerbation of spasticity was one of the most likely potential complications. Identification of these associated conditions and evaluation of risk factors during preoperative examination is important for performing safe anesthesia in these patients.

Effects of Buprenorphine Added to Bupivacaine Infraorbital Nerve Blocks on Isoflurane Minimum Alveolar Concentration Using a Model for Acute Dental/Oral Surgical Pain in Dogs.

Bupivacaine appears to have a duration of action longer than previously reported. Results of this study demonstrate that the addition of buprenorphrine may enhance the analgesic duration of effect for bupivacaine regional nerve blocks. In addition, the use of bupivacaine alone may have analgesia that exceeds 24 hours in many cases. Although not statistically significant based on sample size, 50% of dogs receiving the bupivacaine/buprenorphine regional anesthetic block demonstrated a decreased anesthetic requirement 48 hours postadministration when compared to 25% of dogs receiving the bupivacaine anesthetic. No adverse cardiorespiratory effects were noted secondary to either local anesthetic treatment. Use of bupivacaine may have analgesic effects extending greater than 24 hours (24-72) when used in regional anesthetic blocks in veterinary dental patients with acute dental pain. The addition of buprenorphine to bupivacaine may extend the duration of analgesia (48-96 h). The limited sample size, in addition to patient variability in response to medications, may account for the fact that no differences were detected between the treatments administered.

Emergence agitation after orthognathic surgery: a randomised controlled comparison between sevoflurane and desflurane.

BACKGROUND: This study aimed to compare emergence agitation following sevoflurane and desflurane anaesthesia in adults undergoing orthognathic surgery. The hypothesis was that there might be a difference in the incidence of emergence agitation following sevoflurane and desflurane anaesthesia considering the difference in blood solubility and speed of recovery between the two. METHODS: In this prospective randomised double-blind study, 144 adults undergoing orthognathic surgery were randomly allocated to either sevoflurane or desflurane anaesthesia. The incidence of emergence agitation and possible causative factors were then compared between the groups. RESULTS: The incidence of emergence agitation was lower in the desflurane group than in the sevoflurane group (24% vs. 71%, P < 0.001). In addition, the time intervals between the discontinuation of anaesthetics and the first response, extubation, and discharge from post-anaesthesia care unit were significantly shorter in the desflurane group (P = 0.002, P < 0.001 and P = 0.003, respectively). The other variables were similar in the two groups. CONCLUSIONS: In adults undergoing orthognathic surgery, desflurane anaesthesia was associated with less emergence agitation than was sevoflurane anaesthesia.

Effects of Volatile Anesthetics on Oral Tissue Blood Flow in Rabbits: A Comparison Among Isoflurane, Sevoflurane, and Desflurane.

PURPOSE: The aim of this study was to compare the concentration-dependent effects of isoflurane, sevoflurane, and desflurane on oral tissue blood flow. MATERIALS AND METHODS: Thirty male Japan White rabbits were randomized to receive 1 of 3 volatile anesthetics: isoflurane (group Iso), sevoflurane (group Sevo), or desflurane (group Des). The end-tidal concentration of each volatile anesthetic was regulated to 0.5, 1, and 1.5 minimum alveolar concentrations (MACs). The observed variables were heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, common carotid arterial blood flow, tongue mucosal blood flow, mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow, and lower alveolar tissue blood flow (LBF). RESULTS: The blood pressure in each group tended to decrease depending on the concentration of each volatile anesthetic, with the smallest effect in group Des. BBF and MBF in group Iso were higher than those in group Des at 1 MAC, and MBF and LBF in group Iso were highest at 1.5 MAC. CONCLUSION: The results of this study suggest that each volatile anesthetic produced unique effects on blood flow in oral tissues and circulatory parameters. Among the 3 volatile anesthetics, desflurane produced the smallest effects on oral tissue blood flow.

Intraoperative Blood Loss During Orthognathic Surgery: A Comparison of Remifentanil-Based Anesthesia With Sevoflurane or Isoflurane.

PURPOSE: The aim of the present study was to compare the blood loss with remifentanil-based anesthesia with sevoflurane or isoflurane during orthognathic surgery. PATIENTS AND METHODS: In this randomized controlled clinical trial, the patients who were scheduled for orthognathic surgery were divided into 2 groups: the sevoflurane (Sevo) group and isoflurane (Iso) group. Anesthesia was maintained using end-tidal concentrations of 1.4% sevoflurane or 0.9% isoflurane. Remifentanil was continuously infused at 0.05 to 0.5 µg/kg/min to maintain the mean blood pressure (MBP) at 60 to 65 mm Hg. The intraoperative blood loss was compared between the 2 groups. The Student t test for unpaired samples was used for statistical analysis. P < .05 was considered statistically significant. RESULTS: The study sample included 19 men and 45 women (n = 64). The mean age was 25 years (range 16 to 50). The intraoperative blood loss tended to be greater in the Iso group (n = 32; 4.79 ± 3.22 mL/kg) than in the Sevo group (n = 32; 4.00 ± 1.98 mL/kg). However, the difference between the 2 groups was not significant. CONCLUSION: In a comparison of intraoperative blood loss during remifentanil-based anesthesia with sevoflurane or isoflurane during orthognathic surgery, no difference was observed between the 2 groups.

Pulseless Ventricular Tachycardia During Office-Based Anesthetic in a Four-Year-Old Child.

A 4-year-old 16-kg boy presented for full mouth dental rehabilitation in a private pediatric dental office. The patient had no significant previous medical history. Upon sevoflurane induction by a dentist anesthesiologist, the patient converted from normal sinus rhythm to pulseless ventricular tachycardia. Advanced cardiac life support protocol was initiated. After 2 automatic external defibrillator shocks were delivered in conjunction with epinephrine administration, the patient returned to normal sinus rhythm. The patient was transported via emergency medical service paramedics to a local children's hospital emergency room where he was observed uneventfully for 24 hours prior to discharge.