Effects of changes in end-tidal carbon dioxide tension on oral tissue blood flow and tissue oxygen tension during remifentanil infusion in rabbits.

PURPOSE: The aim of this study was to investigate the effects of end-tidal carbon dioxide tension (ETCO2) changes during remifentanil infusion on mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue oxygen tension (PbO2) and masseter muscle tissue oxygen tension (PmO2) in rabbits. METHODS: Ten male tracheotomized Japan White rabbits were anesthetized and ventilated with sevoflurane. ETCO2 was adjusted to 30 mmHg. After baseline measurement, CO2 was added to the inhaled air, and ETCO2 was increased to 40 and 60 mmHg. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), BBF, MBF, PbO2, and PmO2 were recorded with and without remifentanil infusion at 0.4 µg/kg/min. RESULTS: Two-way repeated measures analysis of variance showed no interaction between ETCO2 and remifentanil in all variables. Remifentanil infusion produced decreases in HR, SBP, MAP, BBF and MBF compared with those without remifentanil infusion, while it did not affect DBP, PbO2 and PmO2. Elevation of ETCO2 from 30 to 60 mmHg produced decreases in HR and MBF, and increases in SBP, DBP, MAP and BBF, while it did not affect PbO2 and PmO2. CONCLUSION: PbO2 and PmO2 remained unchanged despite changes in BBF and MBF during ETCO2 change with or without remifentanil infusion.

Effects of lidocaine, dexmedetomidine, and their combination infusion on postoperative nausea and vomiting following laparoscopic hysterectomy: a randomized controlled trial.

BACKGROUND: A few studies have reported that administration of lidocaine and dexmedetomidine relieves the incidence of postoperative nausea and vomiting (PONV). We explored whether combined infusion of lidocaine plus dexmedetomidine had lower occurrence of PONV undergoing laparoscopic hysterectomy with general anesthesia. METHODS: A total of 248 women undergoing elective laparoscopic hysterectomy were allocated into the following four groups: the control group (group C, n = 62) received an equal volume of saline, the lidocaine group (group L, n = 62) received intravenous lidocaine (bolus infusion of 1.5 mg/kg over 10 min, 1.5 mg/kg/h continuous infusion), the dexmedetomidine group (group D, n = 62) received dexmedetomidine administration (bolus infusion of 0.5 µg/kg over 10 min, 0.4 µg/kg/h continuous infusion), and the lidocaine plus dexmedetomidine group (group LD, n = 62) received combination of lidocaine (bolus infusion of 1.5 mg/kg over 10 min, 1.5 mg/kg/h continuous infusion) and dexmedetomidine administration (bolus infusion of 0.5 µg/kg over 10 min, 0.4 µg/kg/h continuous infusion). The primary outcome was the incidence of nausea, vomiting, and PONV during the first 48 h after surgery. The secondary outcomes included the incidence of total 24 h PONV after surgery, intraoperative remifentanil requirement, postoperative pain visual analogue scale (VAS) scores and fentanyl consumption, the incidence of bradycardia, agitation, shivering, and mouth dry during post-anesthesia care unit (PACU) stay period. RESULTS: The occurrence of nausea and PONV in group LD (5.0 and 8.3%) at 0-2 h after operation was lower than group C (21.7 and 28.3%) (P < 0.05). There was no statistically significant difference with respect to occurrence of nausea and PONV in groups L (13.3 and 20.0%) and D (8.3 and 13.3%) at 0-2 h after operation compared to group C (21.7 and 28.3%). The incidence of nausea, vomiting, and PONV at 2-24 and 24-48 h after surgery in all four groups was not statistically significant. The incidence of total 24 h PONV in group LD (33.3%) was significantly decreased compared to group C (60.0%) (P < 0.05). The cumulative consumption of fentanyl at 6 and 12 h after surgery was significantly reduced in group LD compared to other three groups (P < 0.05). The pain VAS scores were significantly decreased at 2, 6, and 12 h after operation in group LD compared to other three groups (P < 0.05). Remifentanil dose in the intraoperative period was significantly lower in groups LD and D compared with groups C and L (P < 0.05). The number of mouth dry, bradycardia, and over sedation during the PACU stay period was markedly increased in group LD (28.3, 30.0, and 35.0%, respectively) compared with groups C (1.7, 1.7, and 3.3%, respectively) and L (3.3, 5.0, and 6.7%, respectively) (P < 0.05). CONCLUSIONS: Lidocaine combined with dexmedetomidine infusion markedly decreased the occurrence of nausea and PONV at 0-2 h as well as the total 24 h PONV. However, it significantly increased the incidence of mouth dry, bradycardia, and over sedation during the PACU stay period after laparoscopic hysterectomy with general anesthesia. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT03809923 ), registered on January 18, 2019.

Supraglottic jet oxygenation and ventilation reduces desaturation during bronchoscopy under moderate to deep sedation with propofol and remifentanil: A randomised controlled clinical trial.

BACKGROUND: Hypoxaemia is frequently seen during flexible bronchoscopies that are done with a nasal approach under the traditional sedation with propofol. This study investigated the potential benefits of supraglottic jet oxygenation and ventilation (SJOV) using the Wei nasal jet tube (WNJ) in reducing hypoxaemia in patients undergoing bronchoscopy under moderate to deep intravenous sedation using a propofol, lidocaine and remifentanil cocktail. OBJECTIVES: Our primary objective was to evaluate the efficacy and complications of SJOV via the WNJ during flexible bronchoscopy under moderate to heavy sedation with propofol and remifentanil. DESIGN: A randomised controlled clinical trial. SETTING: The 180th Hospital of People's Liberation Army, Quanzhou, China, from 1 June to 1 November 2019. PATIENTS: A total of 280 patients aged ≥18 years with American Society of Anesthesiologists' physical status 1 to 3 undergoing flexible bronchoscopy were studied. INTERVENTIONS: Patients were assigned randomly into one of two groups, a nasal cannula oxygenation (NCO) group (n = 140) using a nasal cannula to deliver oxygen (4 l min-1) or the SJOV group (n = 140) using a WNJ connected to a manual jet ventilator to provide SJOV at a driving pressure of 103 kPa, respiratory rate 20 min-1, FiO2 1.0 and inspiratory:expiratory (I:E) ratio 1:2. MAIN OUTCOME MEASURES: The primary outcome was an incidence of desaturation (defined as SpO2 < 90%) during the procedure. Other adverse events related to the sedation or SJOV were also recorded. RESULTS: Compared with the NCO group, the incidence of desaturation in the SJOV group was lower (NCO 37.0% vs. SJOV 13.1%) (P < 0.001). Patients in the SJOV group had a higher incidence of a dry mouth at 1 min (13.1% vs. 1.5%, P < 0.001) than at 30 min (1.5% vs. 0%, P = 0.159) or at 24 h (0% vs. 0%). There was no significant difference between the groups in respect of sore throat, subcutaneous emphysema or nasal bleeding. CONCLUSIONS: SJOV via a WNJ during flexible bronchoscopy under moderate to deep sedation with propofol and remifentanil significantly reduces the incidence of desaturation when compared with regular oxygen supplementation via a nasal cannula. Patients in the SJOV group had an increased incidence of transient dry mouth. TRIAL REGISTRATION: Registered at www.chictr.org.cn (ChiCTR1900023514).

Comparison of intubating conditions after induction with propofol and remifentanil or sufentanil : Randomized controlled REMIDENT trial for surgical tooth extraction.

PURPOSE: The aim of this study was to compare tracheal intubation conditions after induction of anesthesia with a bolus of propofol-sufentanil or propofol-remifentanil and a rapid induction technique. MATERIAL AND METHODS: A total of 70 patients (American Society of Anesthesiologists (ASA) classification I­II) undergoing outpatient surgery under general anesthesia with intubation for tooth extraction were randomly assigned to two groups in this double-blind study. Patients received either a bolus of remifentanil (3 µg/kg) or sufentanil (0.3 µg/kg) together with 2.5 mg/kg propofol for intubation. The primary outcome was the percentage of excellent intubation conditions and the secondary outcomes were the percentage of patients with a decrease of over 20% in mean arterial pressure (MAP) or heart rate (HR), time to achieve spontaneous respiration, time between the end of surgery and extubation and time to achieve an Aldrete score of 10. VAS pain score was >3 or having laryngeal pain 15 min after arriving in the postanesthesia care unit (PACU) were also analyzed. RESULTS: Intubating conditions (perfect + good conditions) were significantly better with remifentanil than with sufentanil (88.5% vs. 68.6%; p = 0.01). When using remifentanil, the hemodynamic conditions were good. Using remifentanil did not significantly increase the pain score or the laryngeal pain in the recovery room. This was confirmed by no significant differences between the groups for morphine consumption. Remifentanil significantly decreased the time to achieve an Aldrete score of 10. CONCLUSION: When intubation without muscle relaxants is required, intubating conditions are much better when a remifentanil bolus is used compared to a sufentanil bolus. The remifentanil/propofol rapid induction technique is a valuable technique to quickly intubate and achieve good conditions.

Decreases in Oral Tissue Blood Flow Induced by Remifentanil Are Not Accompanied by Deterioration of Oral Tissue Oxygen Tension in Rabbits.

PURPOSE: The purpose of this study was to investigate the effects of remifentanil infusion on tissue blood flow and tissue oxygen tension in the mandibular bone marrow and masseter muscle in rabbits. In addition, changes in tissue oxygen consumption in those tissues during remifentanil infusion were investigated. MATERIALS AND METHODS: Sixteen male tracheotomized Japanese White rabbits were anesthetized with sevoflurane under mechanical ventilation. Under oxygen and air inhalation, fraction of inspiratory oxygen was set at 0.4 and remifentanil was infused at a rate of 0.4 µg ∙ kg-1 ∙ min-1. Measurements were performed before remifentanil infusion, 20 minutes after the start of remifentanil infusion, and 20 and 60 minutes after the completion of remifentanil infusion (n = 8). The observed variables included heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue oxygen tension (PbO2), and masseter muscle tissue oxygen tension (PmO2). Another 8 rabbits were observed for arterial pH, lactate, base excess (BE), and tissue oxygen consumption in the region from which the retromandibular vein received venous blood. Measurements were performed before remifentanil infusion and 20 minutes after the start of remifentanil infusion. RESULTS: HR, SBP, DBP, MAP, BBF, and MBF decreased during remifentanil infusion. PbO2 increased 20 minutes after remifentanil infusion and returned to almost the baseline value 60 minutes after remifentanil infusion. PmO2 did not change throughout the experiment. The difference between the arterial oxygen content of the femoral artery and the venous oxygen content of the retromandibular vein decreased during remifentanil infusion. Arterial pH, lactate, and BE did not change during remifentanil infusion. CONCLUSIONS: Remifentanil decreased BBF and MBF but did not decrease PbO2 and PmO2. It is suggested that tissue oxygen consumption decreased during remifentanil infusion.

Propofol Versus Remifentanil: Which One Is More Effective in Reducing Blood Loss During Orthognathic Surgery? A Randomized Clinical Trial.

PURPOSE: Propofol and remifentanil are 2 useful drugs used in induced hypotensive anesthesia. The purpose of this study was to compare the effects of these drugs on intraoperative blood loss, transfusion requirements, and hemodynamic status during standardized orthognathic surgical procedures. MATERIALS AND METHODS: In this double-blind randomized clinical trial, 50 consecutive healthy patients with Class III skeletal deformity were candidates for bimaxillary orthognathic surgery at Qaem Hospital, Mashhad University of Medical Sciences (Mashhad, Iran), from November 2016 until December 2017. These patients were randomly assigned to 2 equal-number groups to receive hypotensive anesthesia with propofol or remifentanil. Neither the surgeon nor the patients were aware of the study groups, whereas both the student and anesthesiologist were not blinded. Age and gender were recorded, and mean blood loss, mean arterial pressure, and mean heart rate, as well as duration of surgery and duration of general anesthesia, were monitored intraoperatively. The hypotensive anesthetic drugs were the primary predictor variables and the mean blood loss volume was the main outcome in this research. The independent t test and χ2 test were performed for data analysis using SPSS software (version 16; SPSS, Chicago, IL). RESULTS: In this study, 25 patients with a mean age of 22.25 ± 3.31 years were investigated in each group. The mean blood loss volume was 578.26 ± 95.14 mL and 366.67 ± 64.92 mL in the propofol and remifentanil groups, respectively. The independent-samples t test showed that mean blood loss was significantly lower in the remifentanil group than in the propofol group (P = .001). Furthermore, the mean arterial blood pressure was significantly lower in the remifentanil group than in the propofol group (85 ± 20 mm Hg vs 95 ± 15 mm Hg, P < .001). CONCLUSIONS: Hypotensive anesthesia with remifentanil, in comparison with propofol, significantly reduces mean blood loss during orthognathic surgery, which decreases the transfusion requirements and disadvantages of transfusion and blood loss.

Induction of anaesthesia with remifentanil after bolus midazolam administration in Landrace/Large White swine.

OBJECTIVE: To investigate an alternative combination for anaesthesia induction in swine. STUDY DESIGN: Randomized, 'blinded' experimental study. ANIMALS: Forty-five Landrace/Large White swine weighing 20.0±1.5 kg. METHODS: Pulse oximetry, heart rate (HR) and blood pressure were measured after premedication with ketamine, midazolam and atropine as well as after intubation following induction with a fixed dose of 0.2 mg kg-1 midazolam combined with 1, 2, 3, 4 or 5 µg kg-1 remifentanil (groups R1, R2, R3, R4 and R5, respectively). Intubation was evaluated using a numerical scoring system assessing jaw relaxation, resistance to the laryngoscope, vocal cord position, vocal cord movement and response to intubation. The time required to intubate and necessity for an additional midazolam dose were recorded. Baseline and post-intubation variables were compared with paired t tests, whereas for differences between the remifentanil groups the Spearman's rank correlation coefficient was estimated. Multivariate regression analysis was performed to disentangle the effect of remifentanil dose and the additional midazolam. RESULTS: Higher dose of remifentanil was associated with better vocal cord position (p<0.001), better response to intubation (p<0.001), shorter time required for intubation (p=0.030) and less frequent necessity for additional administration of midazolam (p=0.004). In total, 39.5% of the animals required additional midazolam. In groups R1, R4 and R5, there were decreases in HRs (p=0.009, p=0.008 and p=0.032, respectively) between baseline and post-intubation phase; in groups R3 and R4, there were decreases in systolic blood pressure (p=0.040 and p=0.019, respectively). In the multivariate analysis, remifentanil dose was not associated with the observed changes in haemodynamic variables. One animal developed apnoea and four electrocardiographic anomalies; all resolved without pharmaceutical interventions. CONCLUSIONS AND CLINICAL RELEVANCE: A combination of 0.2 mg kg-1 midazolam with 4 or 5 µg kg-1 remifentanil may provide an alternative method of anaesthesia induction for swine.

Remifentanil Reduces Blood Loss During Orthognathic Surgery.

Remifentanil is reported to reduce oral tissue blood flow. We performed a retrospective investigation using logistic regression analysis of anesthesia records to investigate whether the use of remifentanil infusion in a balanced anesthesia technique was useful as a primary technique to reduce blood loss during orthognathic surgery. Subjects were 80 patients who underwent Le Fort I osteotomy and sagittal split ramus osteotomy of the mandible. The variables included gender, age, weight, type of maintenance anesthetic, type and dose or infusion rate of opioid, mean systolic blood pressure (SBP-mean), coefficient of variation of systolic blood pressure (CVSBP) during surgery, mean heart rate (HR-mean), duration of surgery, total blood loss, volume of infusion used, amount of local anesthetic used, body temperature, and urine output. Gender, type of maintenance anesthetic, type of opioid, SBP-mean, CVSBP, HR-mean, and duration of surgery were used as candidates for independent variables. Logistic regression analysis was performed for the selected independent variables with the total blood loss as the dependent variable. The factors associated with the reduction of blood loss were the use of remifentanil (odds ratio, 3.112; 95% CI, 1.166-8.307; P = .023) and smaller CVSBP (odds ratio, 2.747; 95% CI, 1.07-7.053; P = .036). Use of remifentanil and smaller CVSBP were associated with a reduction of blood loss during orthognathic surgery.

Nitroglycerin hypotensive effect and application in a combined surgery for reconstruction after ipsilateral maxillectomy and orbit evisceration.

The oral and maxillofacial region is rich in blood, and it is often difficult to stop bleeding during the operation of maxilla. Nitroglycerin is one of the most commonly used antihypertensive drugs in our hospital. We observed the effect of controlled hypotension in patients with maxillary resection. In group N, the patients had different degrees of tachycardia after using nitroglycerin only. In addition, nitroglycerin has the characteristics of rapid drug resistance. A combined reversed temporal muscle flap and random forehead flap technique was performed successfully to reconstruct the large defect after ipsilateral maxillectomy and orbit evisceration. There were 43 cases used this method during 2014-2016 without large side effects.

The State of UK Dental Anaesthesia: Results From The NAP5 Activity Survey. A national survey by the 5th National Audit Project of the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland.

The National Health Service anaesthesia annual activity (2013) was recently reported by the Fifth National Audit Program of the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland. Within a large dataset were 620 dental cases. Here, we describe this data subset. The estimated annual dental caseload was 111,600:60% were children (< 16 y), 38.5% adults (16 - 65y) and 1.5% the elderly (> 65y). Almost all were elective day procedures (97%) and ASA 1 or 2 patients (95%).The most senior anaesthetist present was a Consultant in 82% and a non-career grade doctor in 14%.Virtually all (98%) cases were conducted during GA. Propofol was used to induce anaesthesia in almost all adults compared with 60% of children. Propofol maintenance was used in 5% of both children and adults. Almost all adults received an opioid (including remifentanil) compared with only 40% of children. Thirty one per cent of children had a GA for a dental procedure without either opioid or LA supplementation. Approximately 50% of adults and 16% of children received a tracheal tube: 20% of children needed only anaesthesia by face mask. These data show that anaesthetists almost always use general anaesthesia for dental procedures and this exposes difficulties in training of anaesthetists in sedation techniques. Dentists, however, are well known to use sedation when operating alone and our report provides encouragement for a comprehensive survey of dental sedation and anaesthesia practice in both NHS and non-NHS hospitals and clinics in the UK.

Remifentanil in Combination With Propofol Is Suitable for Use in the Dental Outpatient Setting.

Although several adjuncts to the general anesthetic propofol have been proposed, there is insufficient research identifying the ideal agent, and in what dosage, to combine with propofol in dental outpatient anesthesia. Here we examined the combination of remifentanil or nitrous oxide and propofol in patients with severe dental avoidance undergoing dental treatment in the outpatient setting. Eighty patients were randomized to 4 groups and administered propofol/saline solution (PS; n = 20), propofol/remifentanil 0.25 µg/kg/min (PRe-0.25; n = 20), propofol/remifentanil 0.125 µg/kg/min (PRe-0.125; n = 20), or propofol/66% nitrous oxide (PN; n = 20). During anesthesia, the bispectral index value was kept between 40 and 60. Body movements and hemodynamic changes during anesthesia, emergence, and recovery as well as anesthetic cost were compared between the combinations. Body movements were observed in all patients administered PS but in no patients administered PRe-0.25, PRe-0.125, or PN. Postoperative nausea was observed in 5 patients (25%) administered PRe-0.25 and in 1 patient (5%) administered PN. Although both PRe-0.125 and PN were useful clinically, PRe-0.125 was the least expensive combination.

Anesthetic Management of a Patient With Takayasu Arteritis.

Takayasu arteritis is a rare chronic progressive panendarteritis involving the aorta and its main branches. Anesthesia in patients with this disease can be complicated by severe uncontrolled hypertension, end-organ dysfunction, and stenosis of major blood vessels. In this case, general anesthesia was induced with sevoflurane and remifentanil without complications. To prevent intraoperative complications, we conducted intubation with a rigid video laryngoscope with careful consideration of the concentrations of analgesics and sedatives used. This case demonstrates the importance of anesthetic techniques for maintaining adequate tissue perfusion without hemodynamic changes in the anesthetic management of patients with Takayasu arteritis.

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.

REMIFENTANIL VS FENTANYL DURING DAY CASE DENTAL SURGERY IN PEOPLE WITH SPECIAL NEEDS: A COMPARATIVE, PILOT STUDY OF THEIR EFFECT ON STRESS RESPONSE AND POSTOPERATIVE PAIN.

BACKGROUND: People with special needs undergoing dental surgery frequently require general anesthesia. We investigated the effect of remifentanil vs fentanyl on stress response and postoperative pain in people with special needs undergoing day-case dental surgery. METHODS: Forty-six adult patients with cognitive impairment undergoing day-case dental surgery under general anesthesia were allocated to receive intraoperatively either fentanyl 50 µg iv bolus (group F, n = 23) or continuous infusion of remifentanil 0.5-1 µg/kg/min (group R, n = 23). Iintraoperative hemodynamic parameters were recorded and serum inflammatory mediators [tumor necrosis factor-α, substance-P], stress hormons (melatonin, cortisol) and ß-endorphin were measured. Postoperative pain was assessed during the first postoperative 12 hours with the Wong-Baker faces pain-rating scale. RESULTS: Demographics were similar in two groups. The two groups did not differ regarding their effects on inflammatory mediators, stress hormons and postoperative pain scores. However, the use of remifentanil prevented intraoperative increases of arterial blood pressure and heart rate. CONCLUSIONS: Remifentanil and fentanyl did not affect differently stress and inflammatory hormones during day-case dental surgery, although remifentanil may render intraoperative management of hemodynamic responses easier. Both opioids are equally efficient for postoperative pain management following dental surgery in people with special needs.

Propofol-remifentanil is More Effective than Propofol-fentanyl in Decreasing Intraoperative Blood Loss during Sagittal Split Ramus Osteotomy.

This study retrospectively compared blood loss during sagittal split ramus osteotomy in patients receiving propofol-remifentanil (R group) and those receiving propofol-fentanyl (F group). All patients underwent sagittal split ramus osteotomy under general anesthesia during the 3-year 4-month period between October 2007 and February 2011 in an operating room at Tokyo Dental College Suidobashi Hospital. Blood loss in the R group was significantly less than that in the F group. Mean arterial pressure and heart rate, measured at 20 and 15 min after tracheal intubation, respectively, were both lower in the R group. No marked change was observed in blood pressure in the R group under general anesthesia, however. Volume of urine was also larger in the R group. The results of this study suggest that remifentanil is effective in reducing intraoperative blood loss during sagittal split ramus osteotomy.

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.

A randomized trial to identify the most effective dose of remifentanil during Le Fort I osteotomy.

PURPOSE: The Le Fort I osteotomy (L-I) requires extensive dissection and manipulation of tissue, causing hemodynamic instability and an undesirable postoperative stress response. This study aimed to clarify the most effective dose of remifentanil during L-I. MATERIALS AND METHODS: This study was designed as a prospective, randomized, controlled double-blinded study. Patients (American Society of Anesthesiologists physical status I to II) undergoing L-I were randomly assigned to receive anesthesia with propofol and remifentanil under 3 remifentanil dose conditions: 0.25 µg/kg/minute (group 1), 0.5 µg/kg/minute (group 2), and 0.75 µg/kg/minute (group 3). All patients underwent L-I with propofol and remifentanil target-controlled anesthesia. The study endpoints were mean arterial pressure (MAP) and heart rate. Data were recorded before L-I (20-minute period before surgery), during L-I (from the beginning of surgery to downfracture), and after L-I (20-minute period after downfracture). Average age, gender, average body mass index, aimed maxillary position, average bispectral index, average surgery time, and average blood loss also were examined. Data were analyzed using the Bartlett test and then 1-way analysis of variance with the Bonferroni multiple comparison test. RESULTS: Data were obtained from 20 patients (9 men, 11 women). The average operating times for groups 1, 2, and 3 were 53.1, 46.7, and 49 minutes, respectively. The age range was 18 to 46 years (average, 26.05 yr). The rate of MAP increase from before to during L-I in group 1 was 10.8% (n = 7). The rate of MAP increase from before to during L-I in group 3 was 2.1% (n = 6). Group 3 showed a significantly lower rate of MAP increase during and after L-I compared with group 1 (P < .05). CONCLUSION: Remifentanil administration at 0.75 µg/kg/minute stabilized hemodynamics during L-I without major side effects. Results indicated that the standard index of remifentanil administration during L-I should be 0.75 µg/kg/minute when using oxygen, propofol, and remifentanil for general anesthesia.

Concomitant administration of nitrous oxide and remifentanil reduces oral tissue blood flow without decreasing blood pressure during sevoflurane anesthesia in rabbits.

PURPOSE: To determine whether continuous administration of nitrous oxide and remifentanil­either alone or together­alters blood flow in oral tissues during sevoflurane anesthesia. METHODS: Eight male tracheotomized Japanese white rabbits were anesthetized with sevoflurane under mechanical ventilation. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), common carotid arterial blood flow (CCBF), tongue mucosal blood flow (TMBF), mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow (UBF), and lower alveolar tissue blood flow (LBF) were recorded in the absence of all test agents and after administration of the test agents (50 % nitrous oxide, 0.4 µg/kg/min remifentanil, and their combination) for 20 min. RESULTS: Nitrous oxide increased SBP, DBP, MAP, CCBF, BBF, MBF, UBF, and LBF relative to baseline values but did not affect HR or TMBF. Remifentanil decreased all hemodynamic variables except DBP. Combined administration of nitrous oxide and remifentanil recovered SBP, DBP, MAP, and CCBF to baseline levels, but HR and oral tissue blood flow remained lower than control values. CONCLUSIONS: Our findings suggest that concomitant administration of nitrous oxide and remifentanil reduces blood flow in oral tissues without decreasing blood pressure during sevoflurane anesthesia in rabbits.

Independent predictors of delay in emergence from general anesthesia.

Some patients with intellectual disabilities spend longer than others in emergence from ambulatory general anesthesia for dental treatment. Although antiepileptic drugs and anesthetics might be involved, an independent predictor for delay of the emergence remains unclear. Thus, a purpose of this study is to identify independent factors affecting the delay of emergence from general anesthesia. This was a retrospective cohort study in dental patients with intellectual disabilities. Patients in need of sedative premedication were removed from participants. The outcome was time until emergence from general anesthesia. Stepwise multivariate regression analysis was used to extract independent factors affecting the outcome. Antiepileptic drugs and anesthetic parameters were included as predictor variables. The study included 102 cases. Clobazam, clonazepam, and phenobarbital were shown to be independent determinants of emergence time. Parameters relating to anesthetics, patients' backgrounds, and dental treatment were not independent factors. Delay in emergence time in ambulatory general anesthesia is likely to be related to the antiepileptic drugs of benzodiazepine or barbiturates in patients with intellectual disability.

Tissue Blood Flow During Remifentanil Infusion With Carbon Dioxide Loading.

The aim of this study was to investigate the effect of changes in end-tidal carbon dioxide tension (ETCO2) during remifentanil (Remi) infusion on oral tissue blood flow in rabbits. Eight male tracheotomized Japan White rabbits were anesthetized with sevoflurane under mechanical ventilation. The infusion rate of Remi was 0.4 µg/kg/min. Carbon dioxide was added to the inspired gas to change the inspired CO2 tension to prevent changes in the ventilating condition. Observed variables were systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), common carotid artery blood flow (CCBF), tongue mucosal blood flow (TBF), mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), upper alveolar tissue blood flow (UBF), and lower alveolar tissue blood flow (LBF). The CCBF, TBF, BBF, UBF, and LBF values were increased, while MBF was decreased, under hypercapnia, and vice versa. The BBF, UBF, and LBF values were increased, while the MBF value was decreased, under hypercapnia during Remi infusion, and vice versa. The BBF, MBF, UBF, and LBF values, but not the CCBF and TBF values, changed along with ETCO2 changes during Remi infusion.