Time Of Loss Of Consciousness Research Articles

Epidural ropivacaine with dexmedetomidine reduces propofol requirement based on bispectral index in patients undergoing lower extremity and abdominal surgeries.

Background and Aim:To assess the amount of propofol required for induction based on bispectral index (BIS) after administering epidural anesthesia with ropivacaine alone and ropivacaine with dexmedetomidine in patients undergoing lower extremities and abdominal surgeries.Subjects and Methods:A double-blinded randomized clinical trial was carried out in 60 patients over a period of 2 years in a tertiary care hospital. American Society of Anaesthesiologists I or II in age group 18–65 years were included in the study. Group R received epidural anesthesia with ropivacaine alone, and Group D received ropivacaine and dexmedetomidine. General anesthesia was induced with propofol under BIS monitoring after 15 min. Onset of sensory and motor block, time for loss of consciousness and total amount of propofol used during induction to achieve the BIS value < 55 were recorded. Student's t-test and Chi-square test were used to find the significance of study parameters.Results:Time of onset of sensory block (Group R 11.30 ± 1.64/Group D 8.27 ± 0.83 min), motor block (Group R 14.16 ± 1.33/Group D 12.63 ± 1.22 min), time for loss of consciousness (Group R 90.57 ± 11.05/Group D 73.67 ± 16.34 s), and total amount of propofol (Group R 129.83 ± 22.38/Group D 92.13 ± 12.93 s) were reduced in Group D which was statistically significant with P < 0.001.Conclusion:Epidural ropivacaine with dexmedetomidine significantly reduces the total propofol dose required for induction of anesthesia. Also, it decreases the onset time of sensory and motor block and provides good hemodynamic stability.

Effect of chemotherapy on sedation with propofol in breast cancer patients

Objective To evaluate the effect of chemotherapy on sedation with propofol in breast cancer patients.Methods One hundred female patients,of ASA physical status Ⅰ or Ⅱ,aged 20-60 yr,scheduled for elective modified radical mastectomy,were divided into 2 groups (n =50 each) according to whether receiving neoadjuvant chemotherapy before operation:non-chemotherapy group (group Ⅰ) and neoadjuvant chemotherapy group (group Ⅱ).The breast cancer patients received operation directly in group Ⅰ.The breast cancer patients received neoadjuvant chemotherapy in group Ⅱ.Epirubicin 75-100 mg/m2 was injected intravenously on 1st and 2nd days,docetaxel 75 mg/m2 was injected intravenously on 3rd day,and 3 weeks were considered as 1 course of treatment.The patients received operation at 3 weeks after the end of 4 courses of treatment in group 1.Anesthesia was induced with propofol given by target-controlled infusion and the target plasma concentration of propofol was 3.5 μg/ml.The time for loss of consciousness and consumption of propofol at loss of consciousness were recorded.Results Compared with group Ⅰ,the time for loss of consciousness was significantly shortened,and the consumption of propofol at loss of consciousness and BIS value were decreased in group Ⅱ.Conclusion Chemotherapy can enhance propofol-induced sedation and promote the onset of propofol in breast cancer patients. Key words: Drug therapy ; Propofol; Conscious sedation; Dose-response relationship, drug

GABAergic transmission in rat pontine reticular formation regulates the induction phase of anesthesia and modulates hyperalgesia caused by sleep deprivation

The oral part of the pontine reticular formation (PnO) contributes to the regulation of sleep, anesthesia and pain. The role of PnO γ-aminobutyric acid (GABA) in modulating these states remains incompletely understood. The present study used time to loss and time to resumption of righting response (LoRR and RoRR) as surrogate measures of loss and resumption of consciousness. This study tested three hypotheses: (i) pharmacologically manipulating GABA levels in rat PnO alters LoRR, RoRR and nociception; (ii) propofol decreases GABA levels in the PnO; and (iii) inhibiting GABA synthesis in the PnO blocks hyperalgesia caused by sleep deprivation. Administering a GABA synthesis inhibitor [3-mercaptopropionic acid (3-MPA)] or a GABA uptake inhibitor [nipecotic acid (NPA)] into rat PnO significantly altered LoRR caused by propofol. 3-MPA significantly decreased LoRR for propofol (-18%). NPA significantly increased LoRR during administration of propofol (36%). Neither 3-MPA nor NPA altered RoRR following cessation of propofol or isoflurane delivery. The finding that LoRR was decreased by 3-MPA and increased by NPA is consistent with measures showing that extracellular GABA levels in the PnO were decreased (41%) by propofol. Thermal nociception was significantly decreased by 3-MPA and increased by NPA, and 3-MPA blocked the hyperalgesia caused by sleep deprivation. The results demonstrate that GABA levels in the PnO regulate the time for loss of consciousness caused by propofol, extend the concept that anesthetic induction and emergence are not inverse processes, and suggest that GABAergic transmission in the PnO mediates hyperalgesia caused by sleep loss.

Cost-effectiveness of different methods of anesthesia for laparoscopic surgery: a prospective, multicenter,randomized, blind clinical study

Objective To compare the cost-effectiveness of inhalation of sevoflurane anesthesia,targetcontrolled infusion (TCI) of propofol anesthesia,and iv propofol for induction of anesthesia-inhalation of sevoflurane for maintenance of anesthesia for laparoscopic surgery in a prospective,multicenter,randomized,blinded clinical study.Methods Three hundred and thirty-six ASA physical status Ⅰ or Ⅱ patients from 4 centers,aged 18-64 yr,with body mass index of 16-30 kg/m2,scheduled for elective laparoscopic surgery,were randomly divided into 3 groups (n =112 each):inhalation of sevoflurane anesthesia group (group S) ; TCI of propofol anesthesia (group P) ; and iv propofol for induction of anesthesia-inhalation of sevoflurane for maintenance of anesthesia group (group PS).Anesthesia was induced with inhalation of 8 ％ sevoflurane in oxygen 8 L/min in group S,with TCI of propofol (target plasma concentration 4 μg/ml) in group P,or with iv injection of propofol 1.5 mg/kg in group PS.After loss of consciousness,fentanyl and vecuronium were injected intravenously in all the patients.The patients were endotracheally intubated and mechanically ventilated.PET CO2 was maintanted at 30-40 mm Hg.Anesthesia was maintanted with inhalation of sevoflurane (end-tidal concentration 0.8 MAC-1.5 MAC) in groups S and PS,or with TCI of propofol (target plasma concentration 3-6 μg/ml) in group P,and intermittent iv boluses of fentanyl and vecuronium were injected when needed in the three groups.Time for loss of consciousness,intubation time,time for recovery of spontaneous breathing,emergence time,extubation time,time for recovery of orientation,time for modified Aldrete score ≥ 9 and duration of stay in postanesthesia care unit and adverse effects during surgery were recorded.The costs of anesthetics were calculated.Results Compared with group P,the time for loss of consciousness,intubation time,time for recovery of orientation,and duration of stay in postanesthesia care unit were significantly shortened in group S,the time for loss of consciousness and intubation time were shortened in group PS,and the cost of propofol and/or sevoflurane,total costs of anesthetics,cost of propofol and/or sevoflurane per hour and total cost of anesthetics per hour were decreased in S and PS groups (P ＜ 0.05).Compared with group S,the time for loss of consciousness was significantly prolonged and the cost of propofol and/or sevoflurane,total costs of anesthetics,cost of propofol and/or sevoflurane per hour and total costs of anesthetics per hour were significantly decreased in group PS (P ＜ 0.05).There was no significant difference in the incidence of adverse effects among the three groups (P ＞ 0.05).Conclusion Induction with iv injection of propofol and maintenance with inhalation of sevoflurane is the most cost-effective method of anesthesia for laparoscopic surgery. Key words: Anesthetics, inhalation ; Propofol; Drug delivery systems ; Cost-benefit analysis ; Laparoscopic surgeries

Tracheal intubation with rocuronium using a "modified timing principle".

BackgroundRapid sequence induction (RSI) is indicated in various situations. Succinylcholine has been the muscle relaxant of choice for RSI, and rocuronium has become an alternative medicine for patients who cannot be administered succinylcholine for various reasons. Although rocuronium has the most rapid onset time among non-depolarizing muscle relaxants, the standard dose of rocuronium (0.6 mg/kg) takes 60 seconds to achieve appropriate muscle relaxation. We evaluated intubating conditions using the "modified timing principle" with rocuronium and succinylcholine.MethodsIn this prospective controlled blinded study, all patients received 1.5 µg/kg fentanyl intravenously with preoxygenation for 2 minutes and were randomized to receive 0.6 mg/kg rocuronium followed by 1.5 mg/kg propofol or 1.5 mg/kg propofol and 1.5 mg/kg succinylcholine. The rocuronium group was intubated just after confirming loss of consciousness, and the succinylcholine group was intubated 1 minute after injecting succinylcholine. Intubation condition, timing of events, and complications were recorded.ResultsAll patients were successfully intubated in both groups. Apnea time of the rocuronium group (38.5 seconds) was significantly shorter than that in the succinylcholine group (100.7 seconds). No significant differences were observed in loss of consciousness time or intubation time. The succinylcholine group tended to show better intubation conditions, but no significant difference was observed. None of the patients complained awareness of the intubation procedure or had respiratory difficulty during a postoperative interview.ConclusionsThe modified RSI with rocuronium showed shorter intubation sequence, acceptable intubation conditions, and a similar level of complications compared to those of conventional RSI with succinylcholine.

Comparison of sevoflurane volatile induction/maintenance anaesthesia and propofol–remifentanil total intravenous anaesthesia for rigid bronchoscopy under spontaneous breathing for tracheal/bronchial foreign body removal in children

Foreign body aspiration is a life-threatening condition, with children under 3 years of age most at risk. This study was designed to compare the clinical characteristics of sevoflurane volatile induction/maintenance anaesthesia (VIMA) and propofol-remifentanil total intravenous anaesthesia (TIVA) for children undergoing rigid bronchoscopy under spontaneous breathing for tracheal/bronchial foreign body removal. Sixty-four children undergoing rigid bronchoscopy were allocated randomly to receive sevoflurane (Group VIMA; n = 32) or propofol-remifentanil (Group TIVA, n = 32) between 2007 and 2009. Respiratory rate, heart rate and mean blood pressure were compared at the time points including baseline level (T 0); laryngoscopy (T lary); insertion of rigid bronchoscope (T bron); 5, 10 and 20 min during procedure (T 5 min, T 10 min, T 20 min); the end of procedure (Tend) and discharge (T dis). Induction time, emergence time, intubating condition scores and the incidence of adverse events were compared. Time for loss of consciousness (Group VIMA 95.6 ± 15.2 s vs. Group TIVA 146.2 ± 26.9 s, P < 0.05), time of Bispectral Index value decreased to 40 (Group VIMA 115.3 ± 16.5 s vs. Group TIVA 160.4 ± 25.8 s, P < 0.05) and emergence time (Group VIMA 10.5 ± 2.6 min vs. Group TIVA 16.9 ± 3.1 min, P < 0.05) in Group VIMA were significantly shorter than those in Group TIVA. Intubating condition scores between the two groups were comparable (8.1 ± 0.9 in Group VIMA vs. 8.1 ± 1.0 in Group TIVA). The incidence rates of breath holding (Group VIMA 6.25% vs. Group TIVA 31.25%, P < 0.05) and desaturation (Group VIMA 15.63% vs. Group TIVA 37.50%, P < 0.05) in Group VIMA were significantly lower than those in Group TIVA. Heart rate, mean blood pressure and respiratory rate were significantly higher in Group VIMA than in Group TIVA. Compared with propofol-remifentanil TIVA, sevoflurane VIMA provides more stable haemodynamics and respiration, faster induction and recovery and higher incidence of excitement in paediatric patients undergoing tracheal/bronchial foreign body removal under spontaneous breathing.

Influence of acute normovolaemic haemodilution on bispectral index monitoring and propofol dose requirements

Numerous medical and physiological conditions that might alter electroencephalography (EEG), such as hypoglycaemia, hypothermia or hypovolaemia, were shown to result in the bispectral Index (BIS) indicating an incorrect hypnotic state. Recently, acute normovolaemic haemodilution (ANH) was shown to be associated with significant impairment of cognitive functions that could alter EEG and consequently BIS monitoring, an EEG derived parameter. In a randomised clinical study, we assessed the effect of ANH on BIS monitoring before induction and after propofol target controlled infusion (TCI) anaesthesia in 45 unmedicated patients randomly allocated to ANH with oxygen insufflation (oxygen group), ANH with air insufflation (air group), or control group. With ANH, mean BIS values briefly declined in the oxygen group (82+/-4) and air group (84+/-3) before returning to baseline values. The loss of consciousness time was significantly shorter, with fewer propofol TCI dose requirements, and BIS was significantly higher in the oxygen group (1.3+/-0.5 min, 2.41+/-0.15 microg/ml, 73+/-7) and air group (1.2+/-0.6 min, 2.44+/-0.17 microg/ml, 75+/-5), compared with the control group (1.7+/-0.4 min, 2.75+/-0.17 microg/ml, 61+/-5), respectively. Whereas, there was no significant difference in BIS values between the oxygen group (38+/-7), air group (36+/-5) and control group (40+/-6) at propofol TCI 4 microg/ml anaesthesia maintenance. BIS values briefly declined with ANH before returning to baseline values before anaesthesia induction. Despite transient ANH enhancement of propofol effect during induction, there was no significant difference in BIS values with or without ANH during propofol maintenance of anaesthesia.

A comparison of halothane and sevoflurane for bronchoscopic removal of foreign bodies in children.

The present study was designed to compare induction and recovery characteristics of sevoflurane and halothane for rigid bronchoscopy for removal of foreign bodies in tracheobronchial tree in children. Forty four children (age 1-4 years) were allocated randomly to two groups to receive either halothane (group H; n=22) or sevoflurane (group S; n=22) in oxygen. A graded inhalation technique was used with maximum inspiratory concentration of 5% for halothane and 8% for sevoflurane. Time for loss of consciousness and induction time in group H and group S were 2.3+/-0.4 min vs 2.2+/-0.4 min (p>0.05) and 4.6+/-0.7 min vs 4.9+/-0.6 min (p>0.05) respectively. Intubation conditions with rigid bronchoscope were similar in both groups. Fewer children in group H had vocal cord movements as compared to group S on laryngoscopy (3 vs 8, p>0.05). Six children in group H and two children in group S had disturbances of cardiac rhythm (p>0.05). Emergence time was significantly shorter in group S as compared to group H (group H - 29.6+/-10.7 min vs group S- 12.3+/-7.6 min, p<0.05). Modified Aldrete's score of 8 was achieved significantly faster in group S as compared to group H (group H - 33.8+/-9.3 min vs group S- 17.3+/-6.8 min, p<0.05). Adverse events during induction and recovery were comparable between the two groups except for significantly high incidence of excitement in group S. In conclusion, halothane is as suitable as sevoflurane for children undergoing rigid bronchoscopy for airway foreign body retrieval, but sevoflurane has a quicker recovery.