Observer's Assessment Of Alertness/Sedation Research Articles

Effects of Continuous Intravenous Infusion of Dexmedetomidine on the Duration of Spinal Anesthesia: A Prospective, Double-Blind, Randomized, Controlled Trial

Background: Spinal anesthesia with sedation is a common anesthetic technique in infraumbilical surgeries. Dexmedetomidine has been widely used as a sedative during spinal anesthesia, and is recognized as an adjuvant that prolongs the duration of spinal anesthesia. We compared the effects of a continuous intravenous infusion of dexmedetomidine to provide intraoperative sedation on the duration of sensory and motor blockade induced by spinal anesthesia, with those of midazolam. Methods: A double-blind randomized controlled trial was performed on 40 patients, aged between 20 and 75 years, who requested intraoperative sedation, and were classified as American Society of Anesthesiologists (ASA) physical status I-II, and underwent elective surgeries under spinal anesthesia. After spinal anesthesia with 13 mg (2.6 ml) of 0.5% hyperbaric bupivacaine, patients were randomized to receive intravenous dexmedetomidine 3 μg/kg/h for 10 mins followed by an infusion of 0.5 μg/kg/h (Group D), or intravenous midazolam 0.15 mg/kg/h for 10 mins followed by an infusion of 0.025 mg/kg/h (Group M). Sedation was titrated to Observer’s Assessment of Alertness/Sedation (OAA/S) score of 3. Sensory and motor blockade was evaluated using the pinprick test and modified Bromage scale, respectively. Results: The time taken to achieve OAA/S score 3 was similar in the two groups. The maximal level of sensory blockade was 5.3 ± 1.3 min in group D and 4.1 ± 1.5 in group M (P = 0.03). No significant differences were observed in the time taken to achieve the maximal level or the two-segment regression time of sensory blockade between the two groups. The time to sensory regression to the L2 level was significantly longer in group D than in group M (234.6 ± 78.1 mins versus 172.4 ± 41.5 mins, respectively, P = 0.008). The time to motor regression to modified Bromage score 1 was significantly longer in group D than in group M (232.2 ± 79.3 versus 176.5 ± 48.8, respectively, P = 0.02). Conclusion: Continuous intravenous dexmedetomidine to provide sedation during spinal anesthesia significantly prolongs the duration of sensory and motor blockade induced by spinal anesthesia over that with midazolam.

Accuracy of anesthesia index for monitoring depth of sedation induced by propofol: a comparison with bispectral index

Objective To evaluate the accuracy of anesthesia index(AI)for monitoring depth of sedation induced by propofol. Methods Thirty patients of both sexes, aged 41-64 yr, with body mass index of 20-30 kg/m2, of American Society of Anesthesiologists physical statusⅠorⅡ, scheduled for elective surgery under general anesthesia, were enrolled in the study.Propofol was given by target-controlled infusion(TCI)with the initial target effect-site concentration(Ce)of 1.2 μg/ml using Marsh pharmacokinetic model, and then the Ce of propofol was increased in 0.3 μg/ml increment, and Observer′s Assessment of Alertness/Sedation(OAA/S)score was evaluated.OAA/S score was 5 before TCI of propofol.When OAA/S score reached 4, 3, 2 and 1 in turn during TCI of propofol, the bispectral index(BIS), AI and corresponding Ce were recorded. Results The correlation coefficients of BIS, AI and Ce levels with the OAA/S scores were rBIS-OAA/S=0.962, rAI-OAA/S=0.960 and rCe-OAA/S =-0.795, respectively(P 0.05). Conclusion AI can accurately monitor the depth of sedation induced by propofol in adult patients without noxious stimuli and there is no significant change in the accuracy in comparison with BIS. Key words: Electroencephalography; Monitoring, physiologic; Propofol; Conscious sedation

Relationship between UGT1A9 gene polymorphisms, efficacy, and safety of propofol in induced abortions amongst Chinese population: a population-based study.

The present study aimed to investigate the influence of UGT1A9 gene polymorphisms on the efficacy of propofol in patients undergoing the painless induced abortion method. A total of 156 women seeking voluntary pregnancy termination procedures were selected for the study, and subsequently underwent painless induced abortions, following anesthesia by means of propofol administration. PCR-restriction fragment length polymorphism (PCR-RFLP) was performed to detect the polymorphisms of UGT1A9 gene at –440C/T, –1818C/T, and –1887T/G loci. The time, effect-site concentration, and bispectral index (BIS) for the Observer’s Assessment of Alertness/Sedation (OAA/S) (up to 4 points) were observed and recorded in patients following discontinuation of propofol. The time and effect-site concentration for BIS reaching 80 in patients following the discontinuation of propofol were observed and recorded. Postoperative observations of adverse reactions, such as nausea, vomiting, and respiratory depression were all made record of. In comparison with patients with UGT1A9 –440C/T CT and TT, those with UGT1A9 –440C/T CC displayed shorter durations of OAA/S by up to 4 points, shorter BIS times reaching 80, as well as higher corresponding effect-site concentrations. No significant differences were detected in the patients with –440C/T, –1818T/C, and –1887T/G in incidence of nausea, vomiting, and respiratory depression. The findings of the study highlighted correlation between UGT1A9 –440C/T gene polymorphisms and positive propofol efficacy in patients undergoing painless induced pregnancy termination procedures.

Can liver cirrhosis patients benefit from target controlled infusion of propofol for conscious sedation during endoscopic variceal ligation?

Background: The aim of the present study was to evaluate the feasibility of conscious sedation using target controlled infusion of propofol combined with a single dose of fentanyl during endoscopic variceal ligation in patients with liver cirrhosis.Methods: Forty-eight patients with liver cirrhosis scheduled for endoscopic variceal ligation were randomly assigned to deep sedation group (DS group) with intravenous bolus of propofol and conscious sedation group (CS group) with target controlled infusion of propofol, 1 μg/kg fentanyl was intravenously injected in each patient before administration of propofol. Cardiorespiratory parameters were monitored, and the side-effects were recorded. The depth of sedation was assessed by both of the sale of observer′s assessment of alertness/sedation (OAA/S) and the bispectral index (BIS). The quality of sedation/analgesia was evaluated by the endoscopist and patients using Visual Analog Scores (VAS). The recovery level was evaluated with the Aldrete scales.Results: No significant differences were found on demographic data and initial parameters in the two groups. Compared with the CS group, the changes of mean arterial pressure (MAP) and heart rate (HR) and the signs of respiratory depression were significant in the DS group (p<0.05). The recovery time in DS group (16.7±2.7 minutes) was much longer than that in the CS group (9.3±3.0 minutes, p<0.01). There was no difference in Visual Analogue Scale scores for endoscopist’s satisfaction between the two groups (9.2±0.6 versus 9.0±0.6, p>0.05), but a higher degree of satisfaction for patient was found in the DS group (9.3±0.6 versus 7.9±0.7, p<0.01).Conclusions: Conscious sedation with target controlled infusion of propofol combined with a single bolus of fentanyl for endoscopic variceal ligation in patients with liver cirrhosis had better hemodynamic stability, less respiratory depression and shorter recovery time.

Pharmacokinetic and pharmacodynamics of intravenous dexmedetomidine in morbidly obese patients undergoing laparoscopic surgery.

This study was designed to investigate the pharmacokinetics and pharmacodynamics of dexmedetomidine in morbidly obese patients undergoing laparoscopic surgery. Morbidly obese (body mass index ≥40kg/m2) and normal weight patients scheduled for elective laparoscopic surgery were included (n=8, each group). After baseline hemodynamic measurement, dexmedetomidine 1μg/kg was administered over 10min. General anesthesia was induced with propofol 1.5mg/kg and fentanyl 4μg/kg 20min after completion of dexmedetomidine infusion; the lungs were mechanically ventilated after tracheal intubation. The pharmacokinetics of dexmedetomidine was analyzed by a noncompartment model. Hemodynamic data and peripheral oxygen saturation (SpO2) were measured up to 30 min after starting dexmedetomidine infusion. Sedation level was measured with the Observer's Assessment of Alertness/Sedation (OAA/S) scale. Peak plasma concentration, area under the curve to infinity, elimination half-life, and apparent volume of distribution were significantly larger in morbidly obese than in normal weight patients (3.75±0.56 vs. 2.54±0.32µg/l, P<0.001; 2174±335 vs. 1594±251ngh/l, P<0.001; 225±55 vs. 158±53min, P=0.02; 310±63 vs. 164±41 l, P<0.001, respectively). Although clearance was also higher in obese patients than in normal body weight patients (58.6±10.7 vs. 44.9±9.0 l/h, P=0.02), it was lower in obese patients than in normal body weight patients after normalization to total body weight (0.47±0.07 vs. 0.64±0.09 l/h/kg, P<0.001). There were no differences in systolic or diastolic blood pressure or heart rate between the two groups within the 30min. Sedation level was deeper and SpO2 was lower in morbidly obese than in normal weight patients. More patients in the morbidly obese patient group experienced deeper sedation after the start of the dexmedetomidine infusion (P<0.05). The pharmacokinetics and pharmacodynamics of dexmedetomidine are significantly different in morbidly obese patients compared with normal weight patients. Level of sedation was significantly deeper, and oxygen saturation was significantly lower, in morbidly obese than in normal weight patients, probably resulting from higher plasma concentration after infusion of 1.0µg/kg. ClinicalTrials.gov (NCT01864187), https://register.clinicaltrials.gov/prs/app/action/LoginUser?ts=1&cx=-jg9qo4 .

Patient controlled epidural analgesia with dexmedetomidine during cesarean section did not impair somatosensory evoked potentials and serum myelin basic protein

Objective To investigate whether patient controlled epidural analgesia(PCEA) with dexmedetomidine(Dex) during cesarean section has no effect on somatosensory evoked potential(SEP) upon lower limb stimulation and serum myelin basic protein(MBP). Methods A total of one hundred and twenty puerperants receiving cesarean section were randomly divided into three groups (n=40): group R received 0.1% ropivacaine only, group RM received 0.002%morphine+0.1% ropivacaine, group RD received 2 μg/kg Dex+0.1% ropivacaine. VAS score, observer's assessment of alertness/sedation(OAA/S) score, HR, MAP were examined 2 h(T1), 4 h(T2),8 h(T3),12 h(T4), 24 h(T5) and 48 h(T6) after surgery. SEPs and concentrations of serum MBP were tested before and after surgery. Adverse effects were also assessed. Results VAS scores at T3, T4, T5 of group RM (1.8±0.8, 1.8±0.8, 1.9±0.9) and RD (1.7±0.6, 1.9±0.7, 1.9±0.5) were lower than those of group R (2.1±0.6, 2.3±0.6, 2.3±0.6)(P 0.05). Satisfaction rates of analgesia and OAA/S scores had no significant difference among three groups (P>0.05). Incidence of nausea, dizziness and pruritus of group RM (32%, 15%, 18%) were higher than those of group R (12%, 0, 0) and group RD (12%, 2%, 2%)(P 0.05). Conclusions Dex 2 μg/kg used for PCEA after cesarean section did not affect serum MBP and SEP, therefore, is a safe analgesic with minimal adverse effect. Key words: Dexmedetomidine; Patient controlld epidural analgesia; Somatosensory evoked potential; Myelin basic protein

Application of close-loop target control infusion system in anesthesia of laparoscopic gastrointestinal surgery

Objective To investigate the feasibility and safety of the close-loop target control infusion system in anesthesia of laparoscopic gastrointestinal. Methods Sixty ASA physical status Ⅰ or Ⅱ patients scheduled for laparoscopic gastrointestinal surgery into two groups (n=30): close-loop target control infusion group (group A) and experienced group (group B). Events in operation were recorded included surgery time, anesthesia time, the consumption of propofol, remifentanil, cisatracurium, extubation time, manually times of narcotic drug and vascular active drug in anesthesia maintenance. The adverse reactions of perioperation included the frequency of intraoperative body dynamic, intraoperative awareness, emergence agitation and delayed awakening were recorded. The postoperative observer's assessment of alertness/sedation(OAA/S) score was recorded. The percentage time narcotrend index (NTI) between 40 to 60 and percentage of time NTI>60 and NTI<40 were also recorded. Results In group A, the extubation time was (7.8±2.4) min, the consumption of propofol and cisatracurium were (13.2±2.8) mg/kg and (0.28±0.06) mg/kg respectively, the number of times of manually controlled narcotic drug delivery was 31. In group B, the extubation time was (12.2±3.6) min, the consumption of propofol and cisatracurium were (15.1±3.1) mg/kg and (0.34±0.10) mg/kg respectively, the number of times of manually delivery narcotic drug was 80. Comparing with group B, they were significantly small in group A (P 60 and NTI<40 of group B were less in group A (P<0.05). The percentage number of time of NTI between 40 and 60 were (81.4±4.8)% in group A and (59.6±8.2)% in group B respectively. Conclusions The close-loop target control infusion system was safe and reliable in anesthesia of laparoscopic gastrointestinal. Comparing with the traditional method, it can reduce the dosage of sedation and muscle relaxants, achieve faster and better quality of the stage of analgesia and reduce the manually number of times of delivering narcotic drug. Key words: Narcotrend monitor; Close-loop; Target control infusion; Anesthesia, general

Comparison between propofol and propofol-remifentanil sedation under target-controlled infusion for impacted supernumerary teeth extraction surgery for children

Objective The aim of this study is to compare sedation titrated under target-controlled infusion of propofol and propofol-remifentanil for impacted supernumerary teeth extraction surgery for children. Methods A total of 60 children with anterior maxillary region impacted supernumerary teeth extraction surgery were divided randomly into two groups, namely, propofol group (group P, n=30) and propofol-remifentanil group (group PR, n=30). In group P, a titrated infusion of propofol was started until the modified observer's assessment of alertness/sedation (OAA/S) scale reached level 3 before the actual surgery. In group PR, a remifentanil infusion with a target plasma concentration of 1 ng·mL⁻¹ was started until the operation was finished. A titrated infusion of propofol was also started until the modified OAA/S score reached level 3 before the actual surgery. The Houpt behavior scale was adopted to evaluate the cooperation of each patient in both groups. The heart rate, blood pressure, respiratory rate, oxyhemoglobin saturation, and Narcotrend index, complications, adverse reactions and propofol infusion of all patients were recorded during the operation. Results The Houpt behavior scales in group PR were better than those in group P (P<0.05). The oxyhemoglobin saturation and respiratory rate in group PR were lower than that in group P (P<0.05). The heart rate, blood pressure and NI in two groups were no significant difference (P>0.05). The incidence of respiratory depression and anterograde amnesia in group PR were higher than that in group P (P<0.05). Conclusion Sedation titrated under the target-controlled infusion of propofol and that titrated under propofol-remifentanil for impacted supernumerary teeth extraction surgery for children are safe. The sedation titrated under target-controlled infusion of propofol-remifentanil is better than sedation by propofol when inhaling oxygen.

A previously published propofol-remifentanil response surface model does not predict patient response well in video-assisted thoracic surgery.

Modern anesthesia usually employs a hypnotic and an analgesic to produce synergistic sedation and analgesia. Two remifentanil–propofol interaction response surface models were used to predict sedation using Observer's Assessment of Alertness/Sedation (OAA/S) scores; one predicts an OAA/S <2 and the other <4. We hypothesized that both models would predict regained responsiveness (RR) after video-assisted thoracic surgery (VATS) to reduce total anesthesia time and make early extubation clinically relevant. We included 30 patients undergoing VATS received total intravenous anesthesia (TIVA) combined with thoracic epidural anesthesia (TEA). Pharmacokinetic profiles were calculated using Tivatrainer. Model predictions were compared with observations to evaluate the accuracy and precision of emergence model predictions. The mean (standard deviation) differences between when a patient responded to their name and the time when the model predicted a 50% probability of patient response were 30.80 ± 17.77 and 13.71 ± 11.35 minutes for the OAA/S <2 model and <4 model, respectively. Both models had a limited ability to predict patient response in our patients. Both models identified target concentration pairs predicting time of RR in volunteers and some elective surgeries, but another model of epidural and intravenous anesthetic combinations may be needed to predict time of RR after VATS under TIVA with TEA.

Optimal dosage of dexmedetomidine for sedation during awake fiberoptic intubation in elder patients

Objective Exploring the effect and the optimal dosage of dexmedetomidine(Dex) during fiberoptic intubation in elder patients. Methods One hundred and twenty patients, ASA Ⅱ or Ⅲ, were randomly divided into four groups with the random number table (n=30): D1, D2, D3 and D4. Four groups received Dex loading dose of 0.2, 0.4, 0.6, 0.8 μg/kg respectively, all the dose were given in ten minutes, then followed with 0.2 μg·kg-1·h-1. MAP, HR, SpO2 maintenance. Observer′s assessment of alertness/sedation(OAA/S) score were recorded at baseline(T0), the time before intubation (T1), the time when bronchofiberscope reaching glottis(T2), 1 min after intubation (T3), 3 min after intubation (T4) and 10 min after intubation (T5). Intubation time, intubation tolerance, and satisfaction rate were also recorded. Results Compared with T0, OAA/S decreased significantly at T1-T5 in group D1, D2, D3 and D4(P<0.05), MAP decreased significantly in group D2, D3 and D4(P<0.05), HR increased significantly at T2 in group D1 and D2(P<0.05). Compared with D1, OAA/S, HR, MAP decreased significantly at T2-T5 in group D3 and D4(P<0.05). Compared with D2, OAA/S decreased significantly at T4-T5 in group D4. MAP and HR were decreased significantly at T2-T5 in group D4. The incubation success rates of 4 groups were 100%. The intubation time in group D2, D3 and D4 were significantly shorter than group D1(P<0.05). Group D2, D3 and D4 were significantly calmer and more cooperative during waking time for fiberoptic incubation, they were also more satisfied with the awake fiberoptic incubation than group D1(P<0.05). Conclusions Dex at a loading dose 0.4-0.6 μg/kg intravenously can be used safely in bronchofibroscopy for elder patients with less cardiovascular and respiratory depression and with more tolerance and satisfaction. Key words: Dexmedetomidine; Aged; Bronchoscopy

The efficacy of dexmedetomidine combined with sufentanil for postoperative analgesia and the effect on immune function and pulmonary complications in patients undergoing operation of lung cancer

Objective To evaluate the efficacy of patient-controlled intravenous analgesia(PCIA) using dexmedetomidine (Dex) combined with sufentanil and the effect on postoperative immune function and pulmonary complications in patients undergoing operation of lung cancer. Methods One hundred and twenty patients with lung cancer were recruited in this study, and randomly divided into two groups for PCIA after thoracoscopic lobectomy, group A(Dex and sufentanil group, n=60) and group B (sufentanil group, n=60). VAS scores, observer's assessment of alertness/sedation(OAA/S) scores, and pulmonary complications were recorded after operation. And the number of natural killer (NK) cells, the level of interferon-γ (IFN-γ) or IL-4, and the ratio of T helper cells 1/T helper cells 2(Th1/Th2) were measured perioperation. Results There was no significant difference between the two groups in VAS, OAA/S scores and additional analgesics(P>0.05). The cases of pruritus, postoperative nausea and vomiting(PONV), and pulmonary complications in group B were 8, 16, 8 and 11, while they were 0, 2, 2 and 3 in group A, respectively(P 0.05), however, in group B, they all restored in 2 weeks after surgery(P>0.05). Conclusions Dex combined with sufentanil is efficient for PCIA in patients undergoing thoracoscopic lobectomy, it could decrease the incidence of pruritus, PONV and pulmonary complications, and promote the recovery of immune function. Key words: Dexmedetomidine; Lobectomy; Patient-controlled analgesia; Immunocompetence; Complication

Comparative Evaluation of the Intranasal Spray Formulation of Midazolam and Dexmedetomidine in Patients Undergoing Surgical Removal of Impacted Mandibular Third Molars: A Split Mouth Prospective Study.

The purpose of this prospective randomized single blinded split mouth study was to conduct a comparative evaluation of the efficacy of intranasal atomised spray formulation of Dexmedetomidine with Midazolam in patients undergoing surgical removal of bilaterally impacted mandibular third molars. This prospective study was conducted in twenty volunteers. Each volunteer underwent the surgical removal of an impacted mandibular third molar at two separate appointments at an interval of two weeks. The first third molar surgery was conducted using either intranasal Midazolam (Group M) or intranasal Dexmedetomidine (Group D). At the second appointment the surgical procedure was performed using the sedative agent not used at the first appointment. The primary testing outcome variables were Plasma oxygen saturation (SpO2), pulse and blood pressure and Modified Observer's Assessment of Alertness/Sedation (OAA/S) scale. These were recorded at predetermined intervals starting 10min before the administration of local anaesthesia and continued up to 10min after completion of the procedure. In addition surgeon's opinion regarding the patient cooperation, event amnesia, post operative nausea & vomiting were obtained. The sample composed of twenty patients (M=9 and F=11). There was statistically no significant difference between Group M and Group D with respect to mean SpO2. Minor differences were however noted at 20 and 30min after sedation. There was no significant difference between the groups with respect to mean pulse rate, blood pressure, OAA/S, event amnesia, post operative nausea and vomiting and patient cooperation. We conclude that Midazolam and Dexmedetomidine are equivalent and can be used in minor oral surgery with minimal complications. These drugs can be used intranasally using nasal atomization device in routine outpatient basis in otherwise normal healthy but anxious patients. All procedures must however be performed in the presence of an anaesthesiologist and with ready availability of emergency drugs and equipment.

The application of conscious sedation with a small dose of dexmedetomidine and sufentanil in elderly patients undergoing multiple intestinal polyps resection

Objective: To explore the effectiveness and feasibility of conscious sedation with a low dose of dexmedetomidine and sufentanil during multiple intestinal polyps resection in elderly patients. Methods: Sixty elderly patients who underwent multiple intestinal polyps resection in Peking University Third Hospital from Janurary to May 2016 were randomly divided into dexmedetomidine group (D group, n=30) and propofol group (P group, n=30). There were 28 males and 32 females with a mean age of (70.4±4.5) years old (range: 65-80 years old). The patients in the dexmedetomidine group received a loading dose of 0.3 μg/kg followed by a continuous infusion of 0.2-0.4 μg·kg-1·min-1 of dexmedetomidine and sufentanil (0.1 μg/kg) respectively.The patients in the propofol group received sufentanil 0.1 μg/kg and propofol 1.5 mg/kg and followed by a continuous infusion of 3-6 mg·kg-1·h-1 of propofol.Blood pressure, heart rate, pulse oxygen saturation (SpO2), respiratory rate and bispectral index (BIS) were recorded at the basic status and at the beginning of operation, 10 min, 20 min, 30 min after operation, the end of operation and departure.The observer's assessment of alertness/sedation (OAA/S) scores and the clinical responses were also recorded.A statistical analysis was performed. Results: All patients in the two groups were sedated compared with baseline.The BIS values of patients in group D at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation were 89.6(87.8-91.0), 79.4(78.0-80.0), 76.9(75.0-80.0), 76.0(73.0-79.0) and 75.6(70.0-79.0) respectively, and those values were all significantly lower than baseline value[96.4(95.0-98.0)], (Z=-4.645, -4.788, -4.787, -4.789, -4.789, P<0.05). The OAA/S score at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation were 4.5(4.0-5.0), 3.4(3.0-4.0), 3.0(3.0-3.0), 3.5(3.0-4.0) and 3.3(3.0-4.0) respectively, and were significantly lower than baseline score [4.8(5.0-5.0)] (Z=-2.828, -4.862, -5.031, -4.420, -4.710, P<0.05). The BIS value of patients in group P at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation were 54.7(50.0-59.3), 54.8(50.0-59.3), 50.7(47.8-56.8), 54.4(51.5-58.0) and 53.7(50.0-57.3) respectively, and were significantly lower than baseline value[95.8(95.0-96.3)] (Z=-4.786, -4.787, -4.788, -4.786, -4.786, P<0.05). The OAA/S score at beginning of the operation , 10 min, 20 min, 30 min after operation and the end of operation were 0.4(0.0-1.0), 0.4(0.0-1.0), 0.4(0.0-1.0), 0.4(0.0-1.0) and 0.4(0.0-1.0) respectively, and were significantly lower than baseline score[4.9(5.0-5.0)] (Z=-4.927, -4.901, -4.912, -4.912, -4.901, P<0.05). The sedation state of group D were lighter than group P. The BIS value and OAA/S score at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation in group D were higher than group P (P<0.05). The breath and circulation were more stable in group D. The mean arterial pressure, breath rate and SpO2 at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation in group D were higher than group P (P<0.05). There was no oxygen desaturation , hypotension and drowsiness in group D and the incidence in group P were 30.0%, 33.3% and 13.3% respectively.The emergency time and duration of stay in the PACU (post anesthesia care unit) were (2.0±1.2) and (22.0±7.4) min in group D, and they were (4.9±2.4) and (35.8±11.6) min in group P (t=-5.839, t=-5.472, P<0.05). There was no difference in surgery time, patient satisfaction and acceptance rate of reexamination (t=-3.031, t=-7.322, t=2.069, P>0.05). Conclusion: Conscious sedation with dexmedetomidine and sufentanil is effective and feasible in elderly patients undergoing multiple intestinal polyps resection.

Sedation with Dexmedetomidine or Propofol Impairs Hypoxic Control of Breathing in Healthy Male Volunteers

In contrast to general anesthetics such as propofol, dexmedetomidine when used for sedation has been put forward as a drug with minimal effects on respiration. To obtain a more comprehensive understanding of the regulation of breathing during sedation with dexmedetomidine, the authors compared ventilatory responses to hypoxia and hypercapnia during sedation with dexmedetomidine and propofol. Eleven healthy male volunteers entered this randomized crossover study. Sedation was administered as an intravenous bolus followed by an infusion and monitored by Observer's Assessment of Alertness/Sedation (OAA/S) scale, Richmond Agitation Sedation Scale, and Bispectral Index Score. Hypoxic and hypercapnic ventilatory responses were measured at rest, during sedation (OAA/S 2 to 4), and after recovery. Drug exposure was verified with concentration analysis in plasma. Ten subjects completed the study. The OAA/S at the sedation goal was 3 (3 to 4) (median [minimum to maximum]) for both drugs. Bispectral Index Score was 82 ± 8 and 75 ± 3, and the drug concentrations in plasma at the sedation target were 0.66 ± 0.14 and 1.26 ± 0.36 μg/ml for dexmedetomidine and propofol, respectively. Compared with baseline, sedation reduced hypoxic ventilation to 59 and 53% and the hypercapnic ventilation to 82 and 86% for dexmedetomidine and propofol, respectively. In addition, some volunteers displayed upper airway obstruction and episodes of apnea during sedation. Dexmedetomidine-induced sedation reduces ventilatory responses to hypoxia and hypercapnia to a similar extent as sedation with propofol. This finding implies that sedation with dexmedetomidine interacts with both peripheral and central control of breathing.

Dexmedetomidine vs propofol-remifentanil conscious sedation for awake craniotomy: a prospective randomized controlled trial

BackgroundAwake craniotomy (AC) is performed for the resection of brain tumours in close proximity to areas of eloquent brain function to maximize reduction of tumour mass and minimize neurological injury. This study compares the efficacy and safety of dexmedetomidine vs propofol-remifentanil-based conscious sedation, during AC for supratentorial tumour resection. MethodsProspective, randomized, controlled trial including 50 adult patients undergoing AC who were randomly assigned to a dexmedetomidine (DEX group, n+25) or propofol-remifentanil group (P-R group, n+25). The primary outcome was the ability to perform intraoperative brain mapping assessed on a numeric rating scale (NRS). Secondary outcome was the efficacy of sedation measured by the modified Observer's Assessment of Alertness/Sedation (OAA/S) scale. Other outcome measures including haemodynamic and respiratory variables, pain, sedation and anxiety scores, adverse events, and patient satisfaction were also compared. ResultsThere were no differences between DEX and P-R groups regarding the ability to perform intraoperative brain mapping [mean NRS score (95% CI): 10.0 (9.9–10.0) vs 9.7 (9.5–10.0), P+0.13] and level of sedation during mapping [mean OAA/S score (95% CI): 4.1 (3.5–4.7) vs 4.3 (3.9–4.7), P+0.51], respectively. Respiratory adverse events were more frequent in the P-R group (20 vs 0%, P+0.021). Heart rate was significantly lower in the DEX group across time (P<0.001); however, the need for treatment of bradycardia was not different between groups. ConclusionsQuality of intraoperative brain mapping and efficacy of sedation with dexmedetomidine were similar to propofol-remifentanil during AC for supratentorial tumour resection. Dexmedetomidine was associated with fewer respiratory adverse events. Clinical trial registrationNCT01545297.

Efficacy of Intranasal Dexmedetomidine for Conscious Sedation in Patients Undergoing Surgical Removal of Impacted Third Molar: A Double-Blind Split Mouth Study.

This study was conducted to evaluate the utility and effectiveness of Intranasal Dexmedetomidine on Sedation status and pain experience of the patients undergoing surgical extraction of impacted third molar. In this double-blind, split mouth study, in 15 patients, evaluations pertaining to classes of third molar impaction was done. Each patient was randomly assigned to receive either intranasal normal saline (placebo group) or intranasal 1.5µg/kg atomized Dexmedetomidine during the first session. The other regimen was used during the second session. Study was conducted for over a period of 120min and data for sedation and pain was collected at an interval of 30min. The collected data was then compared between the two groups within the same patient. Sedation status was assessed by a blinded observer with a modified Observer's Assessment of Alertness/Sedation (OAA/S) 13 scale (Annexure- B). Pain experience was evaluated by Visual Analog Scale (VAS) (Annexure-B). Clinical evaluation for sedation and pain was done by a blinded observer at 30, 60, 90, and 120min after administration of the intranasal solution. The values were then tabulated, and compared between two visits. The mean values of OAA score of Dexmedetomidine group were significantly higher as compared to Placebo group with a 'p' value of 0.000. And the mean values of Pain score of Dexmedetomidine group were significantly lower as compared to Placebo group with a 'p' value 0.009. The results of this study clearly indicated that: Intranasally administered Dexmedetomidine was significantly useful and effective to achieve optimal sedation and analgesia during third molar surgery.

Previously published midazolam–alfentanil response surface model cannot predict patient response well in gastrointestinal endoscopy sedation

BackgroundA response surface model is a mathematical model used to predict multiple-drug pharmacodynamic interactions. With the use of a previously published volunteer model, we tested the accuracy of the midazolam–alfentanil response surface model during gastrointestinal endoscopy. MethodsWe enrolled 35 adult patients scheduled for combined endoscopic procedures. Patients were sedated with intravenous midazolam and alfentanil, and monitored with real-time auditory evoked potential. Sedation Observer's Assessment of Alertness/Sedation (OAA/S) scores were recorded by an independent observer every 2 minutes. Patients with OAA/S scores of ≥4 were designated as “awake”. Pharmacokinetic profiles were calculated using the TIVA trainer. The published response surface model was modified to make estimations more reasonable. Patient response (OAA/S score ≥ 4 or <4) was then estimated using the modified version of the model. ResultsThe average procedural times were 3.3 ± 2 minutes and 6.5 ± 2.3 minutes for esophagogastroduodenoscopy and colonoscopy, respectively. The model poorly predicted patient response during gastrointestinal endoscopic procedure sedation. Accuracy in predicting an OAA/S score of <4 was 6% for the original model and 0% for the modified model. The estimated probability of loss of response ranged from 0.04% to 2.94% at the time of arousal (OAA/S score ≥ 4) and from 0.24% to 15.55% when the patient was asleep (OAA/S score < 4). ConclusionThe model showed significant synergy between midazolam and alfentanil; however, it was inadequate in predicting the response of patients undergoing sedated gastrointestinal endoscopic procedures. Future model parameter adjustments are required.

Modelling of the Sedative Effects of Propofol in Patients undergoing Spinal Anaesthesia: A Pharmacodynamic Analysis.

Sedation can increase patient comfort during spinal anaesthesia. Understanding the relationship between the propofol effect-site concentration (Ce) and patient sedation level could help clinicians achieve the desired sedation level with minimal side effects. We aimed to model the relationship between the propofol Ce and adequate and deep sedation and also incorporate covariates. Thirty patients scheduled for orthopaedic surgery received spinal anaesthesia with 0.5% bupivacaine. Propofol was administered via an effect-site target-controlled infusion device using the Schnider pharmacokinetic model. The pharmacodynamic models for both adequate sedation [Observer's Assessment of Alertness/Sedation (OAA/S) scores of 3-4] and deep sedation (OAA/S scores of 1-2) were developed using nonlinear mixed-effects modelling. Increments in the propofol Ce were associated with increased depths of sedation. In the basic model, the estimated population Ce50 values for adequate and deep sedation were 0.94 and 1.52 μg/ml, respectively. The inclusion of the patient's age and sensory block level for adequate sedation and of age for deep sedation as covariates significantly improved the basic model by decreasing the objective function's minimum value from 10696.72 to 10677.92 (p = 0.0003). The simulated Ce50 values for adequate sedation in 20-year-old patients with a T12 sensory level and in 80-year-old patients with a T4 level were 1.63 and 0.53 μg/ml, respectively. Both age and sensory block level should be considered for adequate sedation, and the propofol concentration should be reduced for elderly patients with a high spinal block to avoid unnecessarily deep levels of sedation.

Swallowing Impairment During Propofol Target-Controlled Infusion

Sedatives can impair the swallowing process. We assessed the incidence and severity of swallowing impairment in patients sedated with propofol at clinically relevant doses. We also identified factors that were predictive of swallowing impairment. In 80 patients scheduled to undergo elective gastrointestinal endoscopy under target-controlled infusion (TCI) propofol sedation, swallowing was evaluated by glottis videoendoscopy, using the Dysphagia Severity Score (DSS) and the Penetration and Aspiration Scale (PAS). The level of sedation was assessed with the Observer's Assessment of Alertness/Sedation (OAAS) scale. Evaluations were obtained within each patient at 3 target effect-site propofol concentrations of 2, 3, and 4 μg/mL (Marsh model). At 2 μg/mL TCI, the OAAS score was 2 in 21 (26.25%) patients and 1 in 59 (73.75%). The OAAS score was 1 in all patients at 3 and 4 μg/mL TCI target. At 3 μg/mL TCI target, 19 (24.36%) patients had a DSS = 3 and 18 patients (23.08%) had a PAS = 7-8 (severe swallowing impairment). DSS was associated with increasing age (5-year odds ratio [OR] 1.53 [1.22-1.93]; P < 0.001), body mass index (BMI; OR 1.24 [1.08-1.42]; P = 0.002), and TCI target (OR 15.80 [7.76-32.20]; P < 0.001). In an alternative model incorporating OAAS instead of TCI target, DSS was associated with increasing age (5-year OR 1.13 [1.02-1.24]; P = 0.014) and BMI (OR 1.08 [1.02-1.15]; P = 0.006) and decreasing OAAS (OR 0.05 [0.006-0.36]; P = 0.003). PAS was associated with increasing age (5-year OR 1.09 [1.04-1.15]; P < 0.001), BMI (OR 1.23 [1.07-1.41]; P = 0.003), and TCI target (OR 15.23 [7.45-31.16]; P < 0.001). In an alternative model incorporating OAAS instead of TCI target, PAS was associated with increasing age (5-year OR 1.14 [1.04-1.26]; P = 0.007) and BMI (OR 1.09 [1.02-1.15]; P = 0.006) and decreasing OAAS (OR 0.05 [0.006-0.41]; P = 0.005). Aspiration due to swallowing impairment may occur during deep sedation produced by propofol at commonly used TCI targets. TCI targets are predictors of swallowing impairment; increased age and high BMI are concomitant risk factors.

A comparative study between dexmedetomidine and propofol in combination with fentanyl for conscious sedation during extracorporeal shock wave lithotripsy

BackgroundExtra-corporeal shock wave lithotripsy (ESWL) is a painful procedure. Sufficient analgesia is mandatory to achieve good treatment results, as well as patient compliance and comfort. Dexmedetomidine, owing to its sedative and its analgesic effects, may be suitable for conscious sedation during ESWL. The aim of this study was to evaluate the use of dexmedetomidine compared with propofol for its safety and efficacy during ESWL.Patients and methodsFifty-two patients were randomly divided into 2 groups that received either dexmedetomidine or propofol for elective ESWL. A dose of 1.5 μg/kg of fentanyl was given intravenously (IV) to all patients 10 min before the ESWL procedure. In the dexmedetomidine group, patient received an initial loading dose of 1 μg/kg of dexmedetomidine infused IV over 10 min, followed by an infusion rate of 0.3 μg/kg/h. In the propofol group, the initial loading dose of 1 mg/kg of propofol was infused IV over 10 min, followed by an infusion rate of 3 mg/kg/h. The Observer’s Assessment of Alertness/Sedation (OOA/S) scores, visual analog scale (VAS), and hemodynamic and respiratory variables were recorded regularly at 5-min interval during ESWL. Hospital discharge time was determined according to Kortilla’s criteria for outpatient surgeries.ResultsThe OOA/S scores in the dexmedetomidine group at the 25- to 45-min assessments were significantly lower than those seen in the propofol group (P < 0.05). The VAS scores for the dexmedetomidine group were significantly lower than those in the propofol group, but only at the 30- to 45-min assessments (P < 0.05). During sedation, the respiratory rate with dexmedetomidine was significantly slower (P < 0.05). Other clinical variables, adverse effects, and hospital discharge times were comparable in both groups (P > 0.05).ConclusionDexmedetomidine with fentanyl can be used safely and effectively, and it may be a valuable alternative to propofol with fentanyl for conscious sedation during ESWL.