Safety and efficacy of remimazolam for general anesthesia in elderly patients undergoing laparoscopic cholecystectomy: a randomized controlled trial

Introduction

There is insufficient evidence regarding the efficacy and safety of remimazolam in elderly patients. Therefore, this study evaluated the differences in the anesthesia characteristics and perioperative hemodynamic profiles of elderly patients receiving total intravenous anesthesia with remimazolam or propofol.

Methods

Eighty-four patients aged >65 years with an American Society of Anesthesiologists physical status of I-III were randomly assigned to Group R (receiving remimazolam, n = 42) or Group P (receiving propofol, n = 42). In Group R, remimazolam was initiated at a rate of 6 mg/kg/h until loss of consciousness (LOC) was achieved and maintained at 1 mg/kg/h subsequently. In Group P, 1.0-1.5 mg/kg of propofol was injected for 1 min and maintained at 100 μg/kg/min subsequently. The maintenance infusion rate was adjusted to maintain an appropriate depth of anesthesia until the end of the surgery. The primary outcome was the time to LOC. The depth of anesthesia scores and hemodynamic profiles were recorded perioperatively.

Results

The time to LOC was significantly longer in Group R (120 s) than in Group P (60 s) (p < 0.001). The time to eye-opening (Group R, 10 min; Group P, 10 min; p = 0.056), the incidence of maintenance of hemodynamic changes within 20% of the peri-anesthetic values, and treatments for hemodynamic instability did not differ significantly between the groups. The depth of anesthesia scores did not differ significantly between the groups; however, the scores were higher in Group R than those in Group P before endotracheal intubation. The hemodynamic parameters did not differ significantly at any time point. The time to extubation was longer in Group R (12 min) than that in Group P (10 min) (p = 0.007). Similarly, the time to discharge from the operating room was significantly longer in Group R (15 min) compared to Group P (12 min) (p = 0.018).

Conclusion

Remimazolam does not exhibit a comparable effect to propofol in terms of anesthesia induction and recovery. However, it demonstrates a similar effect to propofol regarding intraoperative anesthesia depth and hemodynamic profile in elderly patients undergoing remifentanil-based total intravenous anesthesia.

Analgesic Effects of Continuous Wound Infusion Combined with Intravenous Patient-Controlled Analgesia for Thoracic Surgery: A Retrospective Study

Continuous wound infusion analgesia (CWA) with local anesthetics is a loco-regional anesthetic approach for multimodal analgesia management in surgical procedures. This study analyzed whether the combination of intravenous patient-controlled analgesia (PCA) and CWA would be more effective than PCA alone for postoperative analgesia and in preventing chronic postsurgical pain syndrome (PSPS) after thoracic surgeries. We enrolled 166 patients after propensity score matching, the PCA alone (PCA group, n = 83) and the combination of PCA and CWA (PCA-CWA group, n = 83), through a review of electronic medical records. The primary endpoint was the numeric rating scale (NRS) at postoperative days 1, 2, 3, 4, and 5. The secondary endpoint was the presence of PSPS at 3 and 6 months postoperatively. The NRS were lower in the PCA-CWA group than in the PCA group throughout the postoperative period (p < 0.001). The sedation incidence was lower in the PCA-CWA group (1.2%) than in the PCA group (9.6%) (p = 0.034), and there was no significant difference in other postoperative complications or in the incidence of PSPS (p = 1.000). The combination of intravenous PCA and CWA is an effective postoperative analgesic modality for thoracic surgery.

Effective dose of intravenous oxycodone depending on sex and age for attenuation of intubation-related hemodynamic responses

Background/aim

Preoperative intravenous oxycodone may help to prevent or attenuate intubation-related hemodynamic responses (IRHRs), but its pharmacokinetics differs according to age and sex. Therefore, we investigated the 95% effective dose (ED₉₅) of intravenous oxycodone for attenuating all IRHRs, depending on the age and sex of the study population.

Materials and methods

All patients were allocated to one of 6 groups: 1) 20–40 year old males, 2) 41–65yearold males, 3) 66–80 year old males, 4) 20–40 year old females, 5) 41–65yearold females, and 6) 66–80 year old females (groups YM, OM, EM, YF, OF, and EF, respectively). Using Dixon’s up-and-down method, the first patient in each group was slowly injected with intravenous oxycodone (0.1 mg kg^-1) 20 min before intubation. The subsequent patient received the next oxycodone dose, which was decreased or increased by 0.01 mg kg^-1, depending on the “success” or “failure” of attenuation of all IRHRs to within 20% of the baseline values at 1 min after intubation in the previous patient. After obtaining 8 crossover points, predictive ED₉₅ was estimated with probit regression analysis.

Results

ED₉₅ varied greatly according to age and sex. ED₉₅was 0.133 mg kg^-1, 0.181 mg kg^-1, 0.332 mg kg^-1, 0.183 mg kg^-1, 0.108 mg kg^-1, and 0.147 mg kg^-1in groups YM, OM, EM, YF, OF, and EF, respectively.

Conclusion

ED₉₅ is higher in males with increasing age but is ambiguous for females. ED₉₅ is higher in males than in females over 40 years of age but is higher in females than in males under 41 years of age. However, after considering the age and sex of the study population, these results can be used as reference doses for further studies to verify the clinical effects of oxycodone for attenuating all IRHRs.

The Optimizing Background Infusion Mode Decreases Intravenous Patient-Controlled Analgesic Volume and Opioid Consumption Compared to Fixed-Rate Background Infusion in Patients Undergoing Laparoscopic Cholecystectomy: A Prospective, Randomized, Controlled, Double-Blind Study

Background and objectives: The fixed-rate continuous background infusion mode with bolus dosing is a common modality for intravenous patient-controlled analgesia (PCA). However, some patients suffer from inadequate analgesia or opioid-related adverse effects due to the biphasic pattern of postoperative pain. Therefore, we investigated the postoperative analgesic efficacy of PCA using an optimizing background infusion mode (OBIM) where the background injection rate varies depending on the patient’s bolus demand. Materials and Methods: We prospectively enrolled 204 patients who underwent laparoscopic cholecystectomy in a randomized, controlled, double-blind study. Patients were allocated to either the optimizing (group OBIM) or the traditional background infusion group (group TBIM). The numeric rating scale (NRS) score for pain was evaluated at admission to and discharge from the recovery room, as well as at the 6th, 24th, and 48th postoperative hours. Data on bolus demand count, total infused volume, and background infusion rate were downloaded from the PCA device at 30-min intervals until the 48th postoperative hour. Results: The NRS score was not significantly different between groups throughout the postoperative period (p = 0.621), decreasing with time in both groups (p < 0.001). The bolus demand count was not significantly different between groups throughout (p = 0.756). The mean total cumulative infused PCA volume was lower in group OBIM (84.0 (95% confidence interval: 78.9−89.1) mL) than in group TBIM (102 (97.8−106.0) mL; p < 0.001). The total cumulative opioid dose in fentanyl equivalents, after converting sufentanil to fentanyl using an equipotential dose ratio, was lower in group OBIM (714.1 (647.4−780.9) μg) than in group TBIM (963.7 (870.5−1056.9) μg); p < 0.001). The background infusion rate was significantly different between groups throughout the study period (p < 0.001); it was higher in group OBIM than in group TBIM before the 12th postoperative hour and lower from the 18th to the 48th postoperative hour. Conclusions: The OBIM combined with bolus dosing reduces the cumulative PCA volume and opioid consumption compared to the TBIM combined with bolus dosing, while yielding comparable postoperative analgesia and bolus demand in patients undergoing laparoscopic cholecystectomy.

Conus Medullaris Syndrome Due to Missed Thoracolumbar Spinal Fracture in a Patient with Ankylosing Spondylitis who Underwent Hip Surgery

Ankylosing spondylitis (AS) is vulnerable to fracture, and the missed diagnosis can lead to neurological deterioration. Herein, we present the conus medullaris syndrome due to aggravation of the missed spinal fracture in an 85-year-old woman with AS who underwent hip surgery. She underwent osteosynthesis in a supine position with supports under her shoulders and head due to spine deformity with AS, but was fully supine without supports after surgery. She showed complete paraplegia at postoperative 12 h. The re-reading radiological imaging showed the missed spinal fracture, of which the deteriorated dislocation was revealed on the re-examined radiological evaluation. This deterioration was not recovered ultimately despite an emergent surgery. A thorough preoperative assessment is essential to prevent the missed diagnosis of spinal fracture and minimise deterioration due to its dislocation, with specific spine precaution during transport, transfer and positioning.

Effect of different doses of intravenous oxycodone and fentanyl on intubation-related hemodynamic responses: A prospective double-blind randomized controlled trial (CONSORT)

BACKGROUND

Intubation using direct laryngoscopy is a risky and painful procedure that is associated with undesirable hemodynamic changes such as tachycardia, hypertension, and arrhythmia. Recently, intravenous oxycodone was introduced and used for the control of acute postoperative pain and to attenuate intubation-related hemodynamic responses (IRHRs), but there is insufficient information regarding its proper dosage. We investigated the attenuating effects of different doses of oxycodone and fentanyl on IRHRs.

METHODS

For calculating oxycodone effective dose (ED95), which attenuated all IRHR changes to less than 20% over baseline values in 95% of male patients at 1 minute after intubation, oxycodone 0.1 mg/kg was injected for the first patient 1 hour before intubation, and the next dose for each subsequent patient was determined by the response of the previous patient using Dixon up-and-down method with an interval of 0.01 mg/kg. After obtaining the predictive oxycodone ED95, 148 patients were randomly allocated to groups receiving normal saline (group C), oxycodone ED95 (group O1), oxycodone 2 × ED95 (group O2), or fentanyl 2 μg/kg (group F). We recorded the incidence of "success" as a less than 20% change from baseline values in all IRHRs 1 minute after intubation.

RESULTS

The predictive oxycodone ED95 was 0.091 (0.081-0.149) mg/kg. The incidence of "success" was highest in group O2 (75.7%), followed by group O1 (62.2%) and group F (45.9%) with significant differences between the groups (P < .001). The systolic, diastolic, mean arterial pressure, and heart rate were not significantly different among groups after administration of either oxycodone or fentanyl. The percentage hemodynamic changes of the group O2 were significantly lower than those of groups F and O1, but the absolute percentage hemodynamic changes were not significantly different among groups F, O1, and O2. The recalculated oxycodone ED95 with probit analysis (0.269 mg/kg) was needed to prevent any arterial pressure and heart rate changes.

CONCLUSIONS

Oxycodone 0.182 mg/kg is more effective in attenuating all IRHRs than fentanyl 2 μg/kg with safe hemodynamic changes. Further research is required to determine if the recalculated oxycodone ED95 (0.269 mg/kg) is also effective and hemodynamically safe for preventing all IRHRs.

Effect of intraoperative infusion of sufentanil versus remifentanil on postoperative shivering in Korea: a prospective, double-blinded, randomized control study

Background/aim

The number of published papers that compare the incidence of sufentanil- and remifentanil-related postoperative shivering is insufficient. We investigated the incidence of postoperative shivering after total intravenous anesthesia with either sufentanil or remifentanil in patients who underwent elective surgery.

Materials and methods

Eighty-three patients, with a physical status classified as American Society of Anesthesiologists I or II, were randomly allocated to either the remifentanil–propofol (RP group, n = 40) or sufentanil–propofol (SP group, n = 43) group. The primary endpoint was the incidence of postoperative shivering 1 h after entering the recovery room. The secondary endpoints were intraoperative core temperatures of the esophagus and tympanic membrane at 30 min after the induction of anesthesia and at the end of surgery.

Results

The overall postoperative shivering incidence was not significantly different between the RP (15%) and SP (11.6%) groups (P = 0.651). The intraoperative temperatures and their changes (the temperature 30 min after induction minus that after surgery) as measured at the distal esophagus and tympanic membrane were not significantly different between the RP and SP groups.

Conclusion

The incidence of postoperative shivering related to sufentanil was less than that related to remifentanil, with no significant differences in the intraoperative core temperatures.

Mega Acer Kit® is more effective for warming the intravenous fluid than Ranger™ and ThermoSens® at 440 ml/h of infusion rate: an experimental performance study

BACKGROUND

Few studies have investigated the effectiveness of intravenous fluid warmers at low and moderate flow rates below 1,000 ml/h. In this study, we compared the effectiveness of three different fluid warmers at a low flow rate (440 ml/h).

METHODS

We experimentally investigated the fluid warming performances of Mega Acer Kit® (Group M, n = 10), Ranger™ (Group R, n = 10), and ThermoSens® (Group T, n = 10) at 440 ml/h for 60 min. All devices were set at a warming temperature of 41℃ with preheating for 10 min. Intravenous fluids were then delivered through them. The fluid temperature (primary endpoint) was measured at 76 cm from the device after infusion for 60 min. The expected decrease in mean body temperature (secondary endpoint) after 5 h infusion for a 70 kg patient (ΔMBT5) was also calculated.

RESULTS

The fluid temperature (mean [95% CI]) at 76 cm from the device, 60 minutes after the infusion was higher in group M (36.01 [35.73-36.29]℃), compared to groups T (29.81 [29.38-30.24]℃) and R (29.12 [28.52-29.72]℃) (P < 0.001). The ΔMBT5 (mean [95% CI]) was significantly smaller in group M (-0.04 [-0.04 to -0.03]℃) than that in groups T (-0.27 [-0.28 to -0.29]℃; P < 0.001) and R (-0.30 [-0.32 to -0.27]℃; P < 0.001). However, none of the fluid warmers provided a constant normothermic temperature above 36.5℃.

CONCLUSIONS

Mega Acer Kit® was more effective in warming the intravenous fluid with the smallest expected change in the mean body temperature, compared to Ranger™ and ThermoSens®, at a flow rate of 440 ml/h.

Effect of dexamethasone on the onset time and recovery profiles of cisatracurium

BACKGROUND

The effect of dexamethasone injection on cisatracurium-induced neuromuscular block was compared according to different injection time points.

METHODS

One hundred seventeen patients were randomly assigned to three groups: 8 mg of dexamethasone injected intravenously 2-3 h before anesthesia (group A), just before anesthesia induction (group B), and at the end of surgery (control group). Three minutes after anesthesia induction, intubation was performed without neuromuscular blockers, and acceleromyography was initiated. All patients received 0.05 mg/kg cisatracurium; the onset time and recovery profiles were recorded.

RESULTS

Eighty patients were finally enrolled. The onset time (median [interquartile range], seconds) was significantly hastened in group A (520.0 [500.0-560.0], n = 30) compared to that in group B (562.5 [514.0-589.0], n = 22) (P = 0.008) and control group (586.5 [575.0-642.5], n = 28) (P < 0.001). The onset time in group B was faster than the control group (P = 0.015). The recovery time [mean (95% CI) minutes] was significantly hastened in group A [28.5 (27.3-29.6)] compared to that in group B [32.3 (31.0-33.6)] (P < 0.001) and control group [30.9 (29.9-31.8)] (P = 0.015). The total recovery time was significantly hastened more in group A [47.1 (45.5-48.6)] than group B [52.8 (51.6-54.0) minutes] (P < 0.001) and control group [50.5 (48.7-52.3) minutes] (P = 0.008).

CONCLUSIONS

A single dose of 8 mg of dexamethasone hastened the onset and total recovery times of cisatracurium-induced block by approximately 15 and 9%, respectively if administered 2-3 h prior to surgery.

Effects of dexmedetomidine on smooth emergence from anaesthesia in elderly patients undergoing orthopaedic surgery

BACKGROUND

Intraoperative dexmedetomidine may decrease postoperative emergence agitation in elderly patients due to its sedative effect. In this study, we evaluated the effect of adjuvant dexmedetomidine on smooth emergence from anaesthesia after orthopaedic surgery in elderly patients.

METHODS

A total 115 patients (ASA I-II, aged over 65 years) were randomly allocated into four groups. Anaesthesia was maintained with either sevoflurane or total intravenous anaesthesia (TIVA) comprising propofol and remifentanil. Patients were also administered either dexmedetomidine (0.4 μg kg(-1) hr(-1); SD and TD) intraoperatively or normal saline (SN or TN) as a control. The bispectral index (BIS) score was maintained from 40-60 intraoperatively. All anaesthetics and dexmedetomidine were discontinued at surgical conclusion, and the recovery times (durations to a BIS = 60, 70, and 80; eye opening; and extubation) were measured. The mean arterial pressure, heart rate, Ricker's agitation-sedation scale (RSAS), visual analogue scale (VAS) for pain, and incidences of emergence agitation and postoperative nausea and vomiting (PONV) were measured in the recovery room.

RESULTS

Dexmedetomidine significantly decreased the RSAS score in the SD and TD groups, and a calm state postoperatively occurred more frequently in these groups than in the control groups. The heart rate and incidence of emergence agitation were lower in the dexmedetomidine groups. Recovery time was higher in the SD group than in the SN group, and no significant differences occurred between the TN and TD groups. The VAS score was lower in the SD group than in the SN group, and the PONV did not differ regardless of the use of dexmedetomidine.

CONCLUSIONS

Dexmedetomidine may be an effective intraoperative adjuvant for a reducing emergence agitation and smooth emergence from anaesthesia after orthopaedic surgery in elderly patients.

TRIAL REGISTRATION

Current Controlled Trials NCT01851005 .

Clinical evaluation of a newly designed fluid warming kit on fluid warming and hypothermia during spinal surgery

BACKGROUND

The Mega Acer Kit® (MAK) is a newly designed heated and humidified breathing circuit that warms fluid passing through the circuit lumen. In this study, we investigated the system's efficacy for the perioperative prevention of hypothermia and fluid warming.

METHODS

Ninety patients undergoing spinal surgery were enrolled in this study and randomly assigned to 3 groups based on the fluid warming device used: no fluid warming system (Group C, n = 30), via a Standard Ranger (Group R, n = 30), or via the MAK (Group M, n = 30). Distal esophageal temperatures (Teso) and infusion fluid temperature (TF) were recorded at 15 min intervals for duration of 180 min during surgery. If Teso was < 35.0℃, a forced-air convective warming device was used.

RESULTS

Final Teso values were 34.8 ± 0.3℃, 35.1 ± 0.1℃, and 35.8 ± 0.3℃ in groups C, R, and M, respectively (P < 0.01). Teso was significantly higher in group M when compared with that in groups C and R throughout the study period (P < 0.05). The number of patients requiring a forced-air convective warming device was significantly lower in group M (n = 0) when compared with that in groups R (n = 17) and C (n = 30) (P < 0.05). The final infusion fluid temperature was higher in group M when compared with that in groups C and R throughout the study period (35.4 ± 1.0 vs. 23.0 ± 0.3 and 32.8 ± 0.6℃; P < 0.01).

CONCLUSIONS

The MAK is more effective for preventing hypothermia and for warming fluid than the Standard Ranger.

Effects of lidocaine, ketamine, and remifentanil on withdrawal response of rocuronium

BACKGROUND

Rocuronium has been well known to produce withdrawal response in 50-80% patients when administered intravenously. Several drugs are administered prior injection of rocuronium to prevent the withdrawal response. We compared the preventive effect of lidocaine, ketamine, and remifentanil on the withdrawal response of rocuronium.

METHODS

A total of 120 patients undergoing various elective surgeries were enrolled. Patients were allocated into 4 groups according to the pretreatment drugs (Group N, normal saline; Groups L, lidocaine 40 mg; Group K, ketamine 0.5 mg/kg; Group R, remifentanil 1 µg/kg). Patients received drugs prepared by dilution to 3 ml volume before injection of rocuronium. Withdrawal responses after injection of rocuronium were graded on a 4-point scale. Hemodynamic changes were observed before and after administration of pretreatment drugs and after endotracheal intubation.

RESULTS

Incidence of withdrawal response was significantly lower in group L (20%), group K (30%), and group R (0%), than group N (87%). Severe withdrawal response was observed in 5 of the 30 patients (17%) in group L, and in 9 of the 30 patients (30%) in group K. There was no severe withdrawal response in group R. Mean blood pressure and heart rate were significantly decreased in group R compared to other groups.

CONCLUSIONS

It seems that remifentanil (1 µg/kg intravenously) was the strongest and most effective in prevention of withdrawal response after rocuronium injection among the 3 drugs.

Effect on thermoregulatory responses in patients undergoing a tympanoplasty in accordance to the anesthetic techniques during PEEP: a comparison between inhalation anesthesia with desflurane and TIVA

BACKGROUND

It has been known that positive end-expiratory pressure (PEEP) increases the vasoconstriction threshold by baroreceptor unloading. We compared the effect on the thermoregulatory responses according to anesthetic techniques between an inhalation anesthesia with desflurane and a total intravenous anesthesia (TIVA) with propofol and reminfentanil when PEEP was applied in patients undergoing tympanoplasty.

METHODS

Forty-six patients with a scheduled tympanoplasty were enrolled and the patients were divided in two study groups. Desflurane was used as an inhalation anesthetic in group 1 (n = 22), while TIVA with propofol and remifentanil was used in group 2 (n = 24). PEEP was applied by 5 cmH2O in both groups and an ambient temperature was maintained at 22-24℃ during surgery. The core temperature and the difference of skin temperature between forearm and fingertip were monitored for about 180 minutes before and after the induction of general anesthesia.

RESULTS

The final core temperature was significantly higher in group 2 (35.4 ± 0.7℃) than in group 1 (34.9 ± 0.5℃). Peripheral thermoregulatory vasoconstriction was found in 5 subjects (23%) in group 1 and in 21 subjects (88%) in group 2. The time taken for reaching the thermoregulatory vasoconstriction threshold was 151.4 ± 19.7 minutes in group 1 and 88.9 ± 14.4 minutes in group 2.

CONCLUSIONS

When PEEP will be applied, anesthesia with TIVA may have more advantages in core temperature preservation than an inhalation anesthesia with desflurane.

Upper airway compromise by extravasated fluid: a rare complication after arthroscopic repair of atrophic cuff tear

During arthroscopic procedures, leakage of irrigation fluid into surrounding tissue planes is a frequently noticed phenomenon usually clinically asymptomatic and resolving within 12 hours postoperatively. Although rare, this fluid may produce life-threatening complications such as airway compromise. This article describes a case of upper airway obstruction in a 60-year-old man undergoing arthroscopic repair for an atrophic rotator cuff tear. The patient presented with a 6-month history of pain and weakness in the left shoulder. Magnetic resonance imaging studies revealed a massive rotator cuff tear with significant retraction and fatty degeneration of cuff musculature. Perioperatively, all vital cardiorespiratory parameters were within normal limits. Postoperatively, immediately on extubation, he was dyspneic, and examination revealed a diffuse swelling extending from the left shoulder up to the neck and face. He was reintubated and sent to the recovery room, where he recovered 12 hours later. This article highlights the possibility of respiratory compromise due to the extravasation of irrigation fluid into the neck and chest during arthroscopic repair of massive and atrophied cuff tears, even with shorter surgical time as is this case. The widened suprascapular space will offer less resistance to the spread of fluid into the neck and chest from the shoulder. We advocate monitoring the patient continuously to prevent this serious complication from becoming life-threatening.

Carbachol regulates pacemaker activities in cultured interstitial cells of Cajal from the mouse small intestine

We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small intestine by muscarinic stimulation using a whole cell patch clamp technique and Ca2+-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker currents at a holding potential of-70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by 1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic M(3) receptor antagonist, but not by methotramine, a muscarinic M(2) receptor antagonist. Intracellular GDP-beta-S suppressed the carbachol-induced effects. Carbachol-induced effects were blocked by external Na+-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the removal of external Ca2+. In recording of intracellular Ca2+ concentrations using fluo 3-AM dye, carbachol increased intracellular Ca2+ concentrations with increasing of Ca2+ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective cation channels via muscarinic M(3) receptors by a G-protein dependent intracellular Ca2+ release mechanism.

The hemodynamic changes during the infusion of remifentanil for patients under sevoflurane anesthesia during arthroscopic shoulder surgery

BACKGROUND

In spite of its minimal invasiveness, hemodynamic instability frequently happens during arthroscopic procedures. This study was performed to investigate the clinical efficacy of remifentanil for controlling the intra-operative hemodynamics during the performance of arthroscopic shoulder surgery.

METHODS

Sixty patients (ASA class 1 and 2) who were scheduled for arthroscopic shoulder surgery were recruited for this study. After the induction and maintenance of anesthesia with thiopental sodium, rocuronium bromide, sevoflurane and nitrous oxide, the patients were randomly allocated to receive either saline or three different doses of remifentanil (0.03, 0.05 or 0.07 microg/kg/min) to assess the hemodynamic changes such as the systolic blood pressure, the diastolic blood pressure and the heart rate.

RESULTS

The hemodynamics in the remifentanil groups were more stable than those in the saline group (P < 0.05), but there were some cardiovascular side effects such as hypertension (remifentanil 0.03 microg/kg/min), hypotension and bradycardia (remifentanil 0.07 microg/kg/min) with using remifentanil.

CONCLUSIONS

Remifentanil 0.05 microg/kg/min under anesthetic maintenance with sevoflurane showed better hemodynamic stability than the other two remifentanil groups during arthroscopic shoulder surgery.

Effect of tramadol on bispectral index during anesthesia with desflurane

BACKGROUND

This study is aimed to investigate the effect of tramadol on the bispectral index (BIS) during anesthesia with desflurane.

METHODS

One hundred fifty adults, ASA class 1 and 2 patients, scheduled for general anesthesia for elective surgical procedures were included in this study. None of the patients were premedicated and anesthesia was induced with propofol 2 mg/kg and maintained with air-oxygen (FiO2 0.5) and desflurane, adjusted to keep the BIS between from 50 and 60. Forty minutes before completing surgery, the subjects were randomly allocated into 3 groups to receive saline (control group), tramadol 1.5 mg/kg (T1 group) or 3.0 mg/kg (T2 group) intravenously. Hemodynamics and BIS values were then recorded every 5 minutes until completion of the operation, during which time the concentrations of desflurane were not modified.

RESULTS

The mean BIS values after tramadol administration weren't significantly different from the control group throughout the period of observation. No significant changes in the hemodynamics were noted, except systolic and diastolic arterial blood pressure in the T1 and T2 groups significantly increased in the first 5 minutes after the tramadol injection.

CONCLUSIONS

The results indicate that the administration of tramadol while maintaining anesthesia with desflurane, adjusted to keep the BIS between 50 and 60, does not modified BIS values. So, we propose that tramadol can be safely administered as an immediate postoperative analgesia without concern about intra-operative awareness.

Identification of triacylglycerols containing two short-chain fatty acids at sn-2 and sn-3 positions from bovine udder by fast atom bombardment tandem mass spectrometry

Several triacylglycerol (TAG) molecular species, that contain two short-chain fatty acids (C4 to C8) at the sn-2 and sn-3 positions of the glycerol backbone, were isolated from bovine udder by using solvent extraction and silica gel column chromatography. Their structures were identified by fast atom bombardment (FAB) tandem mass spectrometry (MS/MS), based on the information obtained from collision-induced dissociation (CID) spectra of sodium-adducted molecules ([M + Na](+)) of model TAG compounds which had been synthesized from glycerol and appropriate fatty acids. For each species, the relative positions of the three fatty acids on the glycerol backbone, as well as fatty acid composition and double-bond position in the fatty acyl group, were determined. A majority of sodium-adducted molecules observed in the FAB mass spectrum were mixtures of at least two components that have different fatty acid composition but the same molecular mass. In addition, all the components present in mixtures of all the species contain a long-chain fatty acid (C12 to C18) at the sn-1 position, a short-chain fatty acid (C4 to C8) at the sn-2 position, and a butyric acid uniquely at the sn-3 position.