Comparisons of Mechanical Power and Respiratory Mechanics in Pressure-Controlled Ventilation and Volume-Controlled Ventilation during Laparoscopic Cholecystectomy in Elderly Patients.

We compared the effects of pressure-controlled volume-guaranteed ventilation (PCV) and volume-controlled ventilation (VCV) on respiratory mechanics and mechanical power (MP) in elderly patients undergoing laparoscopy. Fifty patients aged 65-80 years scheduled for laparoscopic cholecystectomy were randomly assigned to either the VCV group (n = 25) or the PCV group (n = 25). The ventilator had the same settings in both modes. The change in MP over time was insignificant between the groups (p = 0.911). MP significantly increased during pneumoperitoneum in both groups compared with anesthesia induction (IND). The increase in MP from IND to 30 min after pneumoperitoneum (PP30) was not different between the VCV and PCV groups. The change in driving pressure (DP) over time were significantly different between the groups during surgery, and the increase in DP from IND to PP30 was significantly higher in the VCV group than in the PCV group (both p = 0.001). Changes in MP during PCV and VCV were similar in elderly patients, and MP increased significantly during pneumoperitoneum in both groups. However, MP did not reach clinical significance (≥12 J/min). In contrast, the PCV group had a significantly lower increase in DP after pneumoperitoneum than the VCV group.

Effective concentration of remifentanil for successful i-gel insertion during remimazolam induction.

BACKGROUND: Remifentanil can be used as adjuvants during remimazolam induction without neuromuscular blockade. We evaluated the 95% effective concentration (EC) of remifentanil effect-site concentration (Ce) for the successful insertion of an i-gel using the biased-coin up-and-down method in adult patients during remimazolam induction. METHODS: Forty 19-65 year-old patients scheduled to undergo surgery using i-gel were enrolled. Anesthesia was induced using remimazolam infusion (12 mg/kg/h). Simultaneously, remifentanil was infused at a predetermined Ce. After 5 min of anesthesia induction, the i-gel was inserted. The 95% EC (EC95) of remifentanil in each patient was determined using a biased-coin up-and-down method based on a successful insertion in a preceding patient. The step size of remifentanil Ce was 0.4 ng/ml. If the insertion failed, remifentanil Ce was increased in the next patient. Following successful insertions, the corresponding concentration decreased in subsequent patients with a probability of 1/19 or was maintained with a probability of 18/19. The time from remimazolam infusion initiation to a bispectral index (BIS) < 60 (time to BIS60) and hemodynamic variables were measured and recorded. RESULTS: The EC95 (95% CI) of Ce was 2.07 (1.94, 2.87) ng/ml. The overall time to BIS60 was 154.0 ± 39.9 s. No patient experienced significant hypotension or bradycardia during remimazolam induction. CONCLUSIONS: The EC95 of remifentanil Ce was 2.07 (1.94, 2.87) ng/ml for successful i-gel insertion during remimazolam induction at 12 mg/kg/h without hemodynamic instability in adult patients. Future studies should measure remifentanil Ce in elderly patients or using remimazolam at various infusion doses.

Effect of Erector Spinae Plane Block on Postoperative Pain after Laparoscopic Colorectal Surgery: A Randomized Controlled Study.

The erector spinae plane (ESP) block can be used to reduce pain and opioid requirements after abdominal surgery. We evaluated the effect of the ESP block on postoperative pain score, analgesic use, and quality of recovery (QoR) score in patients undergoing laparoscopy. Fifty-nine patients undergoing elective laparoscopic colorectal surgery were randomly assigned to control (n = 30) or ESPB (n = 29) groups after anesthesia induction. In the ESPB group, an ultrasound-guided ESP block was performed immediately after induction using 20 mL of 0.5% ropivacaine bilaterally. The primary outcome was the postoperative pain score, which was evaluated using the 11-point numeric rating scale (NRS) (0 = no pain, 10 = worst imaginable pain), in the recovery room. NRS "at rest" and "on cough" and total dose of fentanyl rescue (in the recovery room) as well as NRS "at rest" and the cumulative administered fentanyl dose of patient-controlled analgesia (24 h post-surgery) were significantly lower in the ESPB group than in the control group. The postoperative QoR score did not differ between the groups. Bilateral ESP block after induction reduced pain scores and opioid requirements for 24 h postoperatively but did not improve the QoR in patients undergoing laparoscopic colorectal surgery.

Trends in opioid prescribing practices in South Korea, 2009-2019: Are we safe from an opioid epidemic?

Opioid prescribing data can guide regulation policy by informing trends and types of opioids prescribed and geographic variations. In South Korea, the nationwide data on prescribing opioids remain unclear. We aimed to evaluate an 11-year trend of opioid prescription in South Korea, both nationally and by administrative districts. A population-based cross-sectional analysis of opioid prescriptions dispensed nationwide in outpatient departments between January 1, 2009, and December 31, 2019, was conducted for this study. Data were obtained from the Health Insurance Review & Assessment Service. The types of opioids prescribed were categorized into total, strong, and extended-release and long-acting formulation. Trends in the prescription rate per 1000 persons were examined over time nationally and across administrative districts. There are significant increasing trends for total, strong, and extended-release and long-acting opioid prescriptions (rate per 1000 persons in 2009 and 2019: total opioids, 347.5 and 531.3; strong opioids, 0.6 and 15.2; extended-release and long-acting opioids, 6.8 and 82.0). The pattern of dispensing opioids increased from 2009 to 2013 and slowed down from 2013 to 2019. The rate of opioid prescriptions issued between administrative districts nearly doubled for all types of opioids. Prescription opioid dispensing increased substantially over the study period. The increase in the prescription of total opioids was largely attributed to an increase in the prescription of weak opioids. However, the increase in prescriptions of extended-release and long-acting opioids could be a future concern. These data may inform government organizations to create regulations and interventions for prescribing opioids.

A Comparison of Anesthetic Quality Between Interscalene Block and Superior Trunk Block for Arthroscopic Shoulder Surgery: A Randomized Controlled Trial.

BACKGROUND: Interscalene block is the most commonly used nerve block for shoulder surgery, and superior trunk block has been investigated as a phrenic-sparing alternative. This randomized controlled trial compared ultrasound-guided interscalene block and superior trunk block as anesthesia for arthroscopic shoulder surgery. OBJECTIVES: Our aims were to determine the superiority of anesthesia quality and compare the risk of hemidiaphragmatic paralysis between these 2 blocks. STUDY DESIGN: A randomized, controlled trial. SETTING: Department of Anesthesiology and Pain Medicine, Korea University Anam Hospital. METHODS: Forty-eight patients undergoing elective arthroscopic shoulder surgery under an ultrasound guided brachial plexus block were randomized to receive either an interscalene block (ISB group, n = 24) or a superior trunk block (STB group, n = 24) for surgery. Ten milliliters of 2% lidocaine and 10 mL of 0.75% ropivacaine were used as local anesthesia in both brachial plexus block groups (total 20 mL). In the ISB group, the local anesthesia was injected between the C5-C6 root and at the upper part of C5 with equally divided doses. In the STB group, the local anesthesia was injected into the anterior and posterior parts of the superior trunk with equally divided doses. Sensory blockade of each trocar's insulting site (supraclavicular, axillary, and suprascapular nerve areas) and motor blockade of the axillary nerve (shoulder abduction) and the suprascapular nerve (shoulder external rotation) were assessed by a blinded observer at 5-minute intervals for 30 minutes after the block. Anesthesia quality was assessed using 3 grades (excellent/insufficient/failure). The blinded investigator also assessed the grade of hemidiaphragmatic paralysis (normal/partial/complete) by comparing pre- and postoperative chest radiographs. Primary outcome variables were anesthesia grade and rate of hemidiaphragmatic paralysis. Secondary outcome variables were performance time and anesthesia onset time. RESULTS: The anesthetic grade was significantly different between the 2 groups (22/2/0 in the ISB group vs. 16/3/5 in the STB group, P = 0.046). Both groups displayed equivalent incidence of hemidiaphragmatic paralysis (12/6/6 in the ISB group vs. 7/14/3 in the STB group, P = 0.063). No intergroup differences were found in terms of performance time and anesthesia onset time. LIMITATIONS: Our sensory and motor function test was not applied to the subscapular nerve, which serves internal rotation of the humeral head so may be difficult to evaluate in patients with rotator cuff tears. We assessed the diaphragmatic movement by chest radiographs instead of by ultrasound. CONCLUSIONS: The superior trunk block provided lower quality of surgical anesthesia than the interscalene block and did not effectively decrease the risk of hemidiaphragmatic paralysis during arthroscopic shoulder surgery for rotator cuff syndrome.

CONSORT the effect of a bolus dose of dexmedetomidine on postoperative pain, agitation, and quality of recovery after laparoscopic cholecystectomy.

BACKGROUND: The perioperative administration of dexmedetomidine may improve the quality of recovery (QoR) after major abdominal and spinal surgeries. We evaluated the effect of an intraoperative bolus of dexmedetomidine on postoperative pain, emergence agitation, and the QoR after laparoscopic cholecystectomy. METHODS: Patients undergoing elective laparoscopic cholecystectomy were randomized to receive dexmedetomidine 0.5 µg/kg 5 minutes after anesthesia induction (dexmedetomidine group, n = 45) or normal saline (control group, n = 45). The primary outcome was the QoR at the first postoperative day using a 40-item scoring system (QoR-40). Secondary outcomes included intraoperative hemodynamic parameters, postoperative agitation, pain, and nausea and vomiting. RESULTS: The heart rate and the mean blood pressure were significantly lower in the dexmedetomidine group than in the control group (P < .001 and .007, respectively). During extubation, emergence agitation was significantly lower in the dexmedetomidine group than in the control group (23% vs 64%, P < .001). The median pain scores in the post-anesthetic care unit were significantly lower in the dexmedetomidine group than in the control group (4 [2-7] vs 5 [4-7], P = .034). The incidence of postoperative agitation, pain, and nausea and vomiting was not different between the groups. On the first postoperative day, recovery profile was similar between the groups. However, the scores on the emotional state and physical comfort dimensions were significantly higher in the dexmedetomidine group than in the control group (P = .038 and .040, respectively). CONCLUSIONS: A bolus dose of dexmedetomidine after anesthesia induction may improve intraoperative hemodynamics, emergence agitation, and immediate postoperative analgesia. However, it does not affect overall QoR-40 score after laparoscopic cholecystectomy.

A Randomized Comparison Between Two Injections from Two Planes versus Two Injections with a Uniplanar Approach for Ultrasound-Guided Supraclavicular Block.

BACKGROUND: The brachial plexus courses along the lateral to posterior aspect of the subclavian artery located within the supraclavicular region as a trunk or division. Therefore we hypothesized that 2 injections, one along the lateral and one along the posterior aspect of the brachial plexus, could be performed by changing the angle of the ultrasound probe, thereby achieving a 3-dimensional (3-D) even distribution of local anesthetics. Previously, we confirmed the efficacy of this type of approach with that of a single cluster approach. These findings represent a subsequent study. OBJECTIVES: This study was conducted to confirm the superiority of block quality achieved by 2 injections from 2 planes (control group; group C) over 2 injections in one plane (experimental group; group E). STUDY DESIGN: A randomized, controlled trial. SETTING: Department of Anesthesiology and Pain Medicine, Gachon University Gil Medical Center. METHODS: In group C (n = 35), the brachial plexus sheath was penetrated in 2 planes by anteriorly altering the angle of the ultrasound probe without changing its position. In group E (n = 35), the upper and lower portions of the brachial plexus sheath were penetrated in one plane. A total of 15 mL of lidocaine 1.5% containing epinephrine (1:200,000) was injected at each point in both groups. The ultrasound-guided supraclavicular brachial plexus block was evaluated every 5 minutes for 30 minutes. The main outcome variables were rates of blockage of all 4 nerves and ulnar nerve sparing. RESULTS: The rate of blockage of all 4 nerves (median, ulnar, radial, and musculocutaneous nerves) was not significantly different between the 2 groups (94% in group C vs. 86% in group E, respectively; P = 0.232). The number of spared ulnar nerves was similar (1 vs. 5, respectively; P = 0.088). Group procedure times, onset times, and Visual Analog Scale scores for the blocks were similar. LIMITATIONS: For the 2 plane, 2 injection approach, only 2-D imaging was performed rather than 3-D imaging. CONCLUSIONS: Two injections performed in one plane offered similar benefits to 2 injections performed in 2 planes. The 2 techniques provided comparable block qualities and could be viewed as equally effective alternatives.

Effects of an Alveolar Recruitment Maneuver During Lung Protective Ventilation on Postoperative Pulmonary Complications in Elderly Patients Undergoing Laparoscopy.

PURPOSE: Controversy remains over whether alveolar recruitment maneuvers (ARMs) can reduce postoperative pulmonary complications. We hypothesized that performing an ARM in addition to lung protective ventilation (LPV) could improve intraoperative arterial oxygenation and postoperative pulmonary complications (PPCs) in elderly patients undergoing laparoscopy in the Trendelenburg position. PATIENTS AND METHODS: Sixty-two patients (aged 65-85) scheduled for laparoscopic low anterior resection were randomized to receive LPV only (LPV group, n = 32) or LPV with an ARM (ARM group, n = 30). LPV was set to a tidal volume of 6 mL/kg with a positive end expiratory pressure (PEEP) of 5 cmH2O. The ARM was performed by serially increasing the PEEP to 10 cmH2O for 3 breaths, 15 cmH2O for 3 breaths, then 20 cmH2O for 10 breaths, both immediately before and after abdominal insufflation. The primary end-point was the frequency of PPCs such as desaturation (SpO2 <90%), atelectasis, and pneumonia. Secondary end-points were changes in intraoperative respiratory and gas exchange parameters and hemodynamic variables. RESULTS: One patient in the LPV group experienced desaturation on the first postoperative day. The frequency of chest X-ray abnormalities such as atelectasis or pleural effusion was comparable between groups (6 (19%) and 5 (17%) patients, respectively, P = 0.676). Changes in other respiratory, gas exchange and hemodynamic parameters over time were not significantly different between the groups. However, vasopressor requirements during surgery were higher in the ARM than the LPV group (9 (30%) and 2 (6%) patients, respectively, P = 0.014). CONCLUSION: This study suggests that performing an ARM during LPV may not improve postoperative respiratory outcomes and intraoperative oxygenation compared to LPV alone in geriatric patients undergoing laparoscopy in the Trendelenburg position. In addition, since the ARM could cause a significant deterioration in hemodynamic parameters, applying ARM to elderly patients should be carefully considered.

Effects of different sugammadex doses on the train of four ratio recovery progression during rocuronium induced neuromuscular blockade in the rat phrenic nerve hemidiaphragm.

BACKGROUND: In this study, we used an ex-vivo model to investigate the recovery pattern of both the train-of-four (TOF) ratio and first twitch tension of TOF (T1), and determined their relationship during recovery from rocuronium-induced neuromuscular blockade at various concentrations of sugammadex. METHODS: Tissue specimens of the phrenic nerve-hemidiaphragm were obtained from 60 adult Sprague-Dawley rats. Each specimen was immersed in an organ bath filled with Krebs buffer solution and stimulated with the TOF pattern using indirect supramaximal stimulation at 20-second intervals. After a 30-minute stabilization period, rocuronium loading and booster doses were serially administered at 10-minute intervals in each sample until > 95% depression of T1 was confirmed. Specimens were randomly allocated to either the control group (washout) or to one of five sugammadex concentration groups (0.75, 1, 2, 4, or 8 times equimolar doses of rocuronium to produce >95% T1 depressions; SGX0.75, SGX1, SGX2, SGX4, and SGX8, respectively). Recovery from neuromuscular blockade was monitored using T1 and the TOF ratio simultaneously until the recovery of T1 to > 95% and the TOF ratio to > 0.9. RESULTS: Statistically significant intergroup differences were observed between the recovery patterns of T1 and the TOF ratio (TOFR, p<0.050), except between SGX2 and SGX4 groups. TOFR/T1 values were maintained at nearly 1 in the control, SGX0.75, and SGX1 groups; however, they were exponentially decayed in the SGX2, SGX4, and SGX8 groups. CONCLUSIONS: Recovery of the TOF ratio may be influenced by the sugammadex dose, and a TOF ratio of 1.0 may be achieved before full T1 recovery if administration of sugammadex exceeds that of rocuronium.

Effects of adenosine receptor agonist on the rocuroniuminduced neuromuscular block and sugammadex-induced recovery.

BACKGROUND: Several types of receptors are found at neuromuscular presynaptic membranes. Presynaptic inhibitory A1 and facilitatory A2A receptors mediate different modulatory functions on acetylcholine release. This study investigated whether adenosine A1 receptor agonist contributes to the first twitch tension (T1) of train-of-four (TOF) stimulation depression and TOF fade during rocuronium-induced neuromuscular blockade, and sugammadex-induced recovery. METHODS: Phrenic nerve-diaphragm tissues were obtained from 30 adult Sprague-Dawley rats. Each tissue specimen was randomly allocated to either control group or 2-chloroadenosine (CADO, 10 µM) group. One hour of reaction time was allowed before initiating main experimental data collection. Loading and boost doses of rocuronium were sequentially administered until > 95% depression of the T1 was achieved. After confirming that there was no T1 twitch tension response, 15 min of resting time was allowed, after which sugammadex was administered. Recovery profiles (T1, TOF ratio [TOFR], and recovery index) were collected for 1 h and compared between groups. RESULTS: There were statistically significant differences on amount of rocuronium (actually used during experiment), TOFR changes during concentration-response of rocuronium (P = 0.04), and recovery profiles (P < 0.01) of CADO group comparing with the control group. However, at the initial phase of this experiment, dose-response of rocuronium in each group demonstrated no statistically significant differences (P = 0.12). CONCLUSIONS: The adenosine A1 receptor agonist (CADO) influenced the TOFR and the recovery profile. After activating adenosine receptor, sugammadex-induced recovery from rocuronium-induced neuromuscular block was delayed.

Efficacy of Ultrasound-Guided Serratus Plane Block on Postoperative Quality of Recovery and Analgesia After Video-Assisted Thoracic Surgery: A Randomized, Triple-Blind, Placebo-Controlled Study.

BACKGROUND: The optimal regional technique for analgesia and improved quality of recovery after video-assisted thoracic surgery (a procedure associated with considerable postoperative pain) has not been established. The main objective in this study was to compare quality of recovery in patients undergoing serratus plane block (SPB) with either ropivacaine or normal saline on the first postoperative day. Secondary outcomes were analgesic outcomes, including postoperative pain intensity and opioid consumption. METHODS: Ninety patients undergoing video-assisted thoracic surgery were randomized to receive ultrasound-guided SPB with 0.4 mL/kg of either 0.375% ropivacaine (SPB group) or normal saline (control group) after anesthetic induction. The primary outcome was the 40-item Quality of Recovery (QoR-40) score at 24 hours after surgery. The QoR-40 questionnaire was completed by patients the day before surgery and on postoperative days 1 and 2. Pain scores, opioid consumption, and adverse events were assessed for 2 days postoperatively. RESULTS: Eighty-five patients completed the study: 42 in the SPB group and 43 in the control group. The global QoR-40 scores on both postoperative days 1 and 2 were significantly higher in the SPB group than in the control group (estimated mean difference 8.5, 97.5% confidence interval [CI], 2.1-15.0, and P = .003; 8.5, 97.5% CI, 2.0-15.1, and P = .004, respectively). The overall mean difference between the SPB and control groups was 8.5 (95% CI, 3.3-13.8; P = .002). Pain scores at rest and opioid consumption were significantly lower up to 6 hours after surgery in the SPB group than in the control group. Cumulative opioid consumption was significantly lower up to 24 hours postoperatively in the SPB group. CONCLUSIONS: Single-injection SPB with ropivacaine enhanced the quality of recovery for 2 days postoperatively and improved postoperative analgesia during the early postoperative period in patients undergoing video-assisted thoracic surgery.

The effect of intraoperative dexmedetomidine on acute kidney injury after pediatric congenital heart surgery: A prospective randomized trial.

BACKGROUND: Dexmedetomidine has been reported to have a renal protective effect after adult open heart surgery. The authors hypothesized that intraoperative infusion of dexmedetomidine would attenuate the decrease in renal function after pediatric open heart surgery. METHODS: Twenty-nine pediatric patients (1-6 years) scheduled for atrial or ventricular septal defect repair were randomly assigned to receive either continuous infusion of normal saline (control group, n = 14) or dexmedetomidine (a bolus dose of 0.5 µg/kg and then an infusion of 0.5 µg/kg/h) (dexmedetomidine group, n = 15) from anesthesia induction to the end of cardiopulmonary bypass. Serum creatinine (Scr) was measured before surgery (T0), 10 minutes after anesthesia induction (T1), 5 minutes after cardiopulmonary bypass weaning (T2), 2 hours after T2 (T3), and after postoperative day 1 (POD1) and postoperative day 2 (POD2) and estimated glomerular filtration rates (eGFRs) were calculated. Renal biomarkers were measured at T1, T2, and T3. Acute kidney injury (AKI) was defined as an absolute increase in Scr of ≥ 0.3 mg/dL or a percent increase in Scr of ≥50%. RESULTS: The incidence of AKI during the perioperative period was significantly higher in the control group than in the dexmedetomidine group (64% [9/14] vs 27% [4/15], P = .042). eGFR was significantly lower in the control group than in the dexmedetomidine group at T2 (72.6 ±â€Š15.1 vs 83.9 ±â€Š13.5, P = .044) and T3 (73.4 ±â€Š15.4 vs 86.7 ±â€Š15.9, P = .03). CONCLUSION: Intraoperative infusion of dexmedetomidine may reduce the incidence of AKI and suppress post-bypass eGFR decline.

Discordant lumbar epidural hematoma after caudal steroid injection: A case report (CARE-compliant).

RATIONALE: Caudal epidural injection is one of the conventional treatments of chronic back pain. Even though spinal epidural hematoma after caudal epidural injection is rare but it can cause serious neurologic complication. PATIENT CONCERNS: An 83-year-old woman taking cilostazol received caudal epidural steroid injection because of her chronic back pain. Six hours later, she experienced an acute hip pain which worsened with time. DIAGNOSIS: Magnetic resonance image showed acute cord compression due to a spinal epidural hematoma at L2-S1 level with concomitant central canal compromise at L2/3, L3/4 level. INTERVENTIONS: Emergency decompressive laminectomy and evacuation of the lumbar epidural hematoma were performed. OUTCOMES: All of her symptoms were resolved over the 72 hours following surgery. LESSONS: Continuous vigilance after caudal epidural injection is important to prevent catastrophic neurologic deterioration with early detection and early treatment.

CONSORT the effect of intraoperative dexmedetomidine on hemodynamic responses during emergence from nasotracheal intubation after oral surgery.

BACKGROUND: Dexmedetomidine provides smooth emergence with reduced agitation. The authors hypothesized low-dose dexmedetomidine infusion might contribute to hemodynamic stability during and after nasotracheal tube extubation. METHODS: Ninety-three adult patients scheduled for oral and maxillofacial surgery were enrolled in this prospective study. Patients were randomly assigned to receive normal saline (control group, n = 31), dexmedetomidine at 0.2 µg/kg/h (DEX0.2 group, n = 31), or dexmedetomidine at 0.4 µg/kg/h (DEX0.4 group, n = 31). Mean arterial pressure (MAP), heart rate (HR), and response entropy (RE) and state entropy (SE) were recorded during emergence from anesthesia. RESULTS: Extubation times were similar in the 3 groups. Mean MAP was significantly lower at eye opening (T3) and immediately after extubation (T4) in the DEX0.2 (P = .013 and .003, respectively) and DEX0.4 group (P = .003 and .027, respectively) than in the control group. At T3 and T4, mean HR was significantly higher in the control group than in the DEX0.2 (P = .014 and .022, respectively) or DEX0.4 groups (P = .003 and <.001, respectively). In the postanesthetic care unit, mean MAP and HR were significantly lower in the DEX0.2 (P = .03 and .022, respectively) and DEX0.4 groups (P = .027 and <.001, respectively) than in the control group. CONCLUSION: Intraoperative dexmedetomidine infusion at rates of 0.2 or 0.4 µg/kg/h during oral and maxillofacial surgery could provide stable hemodynamic profiles during anesthetic emergence from nasotracheal intubation without delaying extubation times.

The Effect of Equal Ratio Ventilation on Oxygenation, Respiratory Mechanics, and Cerebral Perfusion Pressure During Laparoscopy in the Trendelenburg Position.

The aim of this study was to investigate the effects of equal ratio ventilation (ERV) on oxygenation, respiratory mechanics, and the cerebral perfusion pressure during pneumoperitoneum in the Trendelenburg position. Thirty patients undergoing laparoscopic low anterior resection (25 to 65 y) were enrolled. Mechanical ventilator was set to volume-controlled mode at an inspiratory to expiratory (I:E) ratio of 1:2 with a tidal volume of 8 mL/kg of ideal body weight with a 5 cm H2O positive end-expiratory pressure. Twenty minutes after pneumoperitoneum in the Trendelenburg position, the I:E ratio was changed to 1:1 for 20 minutes and then restored to 1:2. No significant changes in arterial oxygen tension and respiratory compliance after adopting ERV. Mean arterial pressure and cerebral perfusion pressure decreased significantly over time after adopting the Trendelenburg position during pneumoperitoneum (P=0.014 and 0.005, respectively). In conclusion, there was no improvement in oxygenation or respiratory mechanics with ERV.

Male patients require higher optimal effect-site concentrations of propofol during i-gel insertion with dexmedetomidine 0.5 µg/kg.

BACKGROUND: The pharmacokinetics and pharmacodynamics of an anesthetic drug may be influenced by gender. The purpose of this study was to compare effect-site half maximal effective concentrations (EC50) of propofol in male and female patients during i-gel insertion with dexmedetomidine 0.5 µg/kg without muscle relaxants. METHODS: Forty patients, aged 20-46 years of ASA physical status I or II, were allocated to one of two groups by gender (20 patients per group). After the infusion of dexmedetomidine 0.5 µg/kg over 2 min, anesthesia was induced with a pre-determined effect-site concentration of propofol by target controlled infusion. Effect-site EC50 values of propofol for successful i-gel insertion were determined using the modified Dixon's up-and-down method. RESULTS: Mean effect-site EC50 ± SD of propofol for successful i-gel insertion was significantly higher for men than women (5.46 ± 0.26 µg/ml vs. 3.82 ± 0.34 µg/ml, p < 0.01). The EC50 of propofol in men was approximately 40% higher than in women. Using isotonic regression with a bootstrapping approach, the estimated EC50 (95% confidence interval) of propofol was also higher in men [5.32 (4.45-6.20) µg/ml vs. 3.75 (3.05-4.43) µg/ml]. The estimated EC95 (95% confidence interval) of propofol in men and women were 5.93 (4.72-6.88) µg/ml and 4.52 (3.02-5.70) µg/ml, respectively. CONCLUSIONS: During i-gel insertion with dexmedetomidine 0.5 µg/kg without muscle relaxant, male patients had higher effect-site EC50 for propofol using Schnider's model. Based on the results of this study, patient gender should be considered when determining the optimal dose of propofol during supraglottic airway insertion. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02268656. Registered August 26, 2014.

The Effect of Ventilation Strategy on Arterial and Cerebral Oxygenation During Laparoscopic Bariatric Surgery.

BACKGROUND: We investigated the effect of prolonged inspiratory to expiratory (I/E) ratio ventilation on respiratory mechanics, gas exchange, and regional cerebral oxygen saturation (rSO2) in obese patients undergoing laparoscopic bariatric surgery in the reverse Trendelenburg position. METHODS: Twenty-eight adult patients scheduled for laparoscopic sleeve gastrectomy were enrolled in this prospective observational study. After anesthesia induction, pressure-controlled ventilation was conducted initially at a conventional I/E ratio of 1:2 and a positive end-expiratory pressure of 5 cmH2O. Twenty minutes after pneumoperitoneum, the I/E ratio was changed to 1:1 for 20 min and then to 2:1 for 20 min. Hemodynamic variables, end-tidal carbon dioxide tension, rSO2, arterial blood gas analysis results, and respiratory variables were recorded. RESULTS: No significant changes in hemodynamic values and rSO2 were observed during the study. Peak airway pressure was significantly lower, but mean airway pressure and dynamic compliance were significantly higher at I/E ratios of 1:1 and 2:1 than during conventional I/E ratio ventilation. Arterial oxygen tension (PaO2) value was significantly higher (p = 0.009), and alveolar-arterial oxygen tension gradient was lower (p = 0.015) at an I/E ratio of 2:1 than during conventional ratio ventilation. CONCLUSIONS: The use of prolonged I/E ratio of 2:1 significantly improved respiratory mechanics and arterial oxygenation without causing hemodynamic derangements or cerebral desaturation during laparoscopic bariatric surgery in the reverse Trendelenburg position.

Implications of palonosetron in elderly patients undergoing laparoscopic cholecystectomy with respect to its anti-shivering effect.

BACKGROUND: The elderly are vulnerable to hypothermia and have a higher risk of cardiovascular events induced by marked increases in oxygen consumption due to shivering. Five-hydroxytryptamine-3 (5-HT3) receptor antagonists have been previously reported to reduce post-anesthesia shivering. AIM: In the present study, the authors investigated the effects of palonosetron, a new-generation 5-HT3 antagonist, on core hypothermia and the incidence of shivering after laparoscopic cholecystectomy in elderly patients. METHODS: Forty-eight patients (65-80 years) were randomly assigned to one of two groups and administered palonosetron 0.075 mg (palonosetron group, n = 24) or the same volume of normal saline (control group, n = 24) before anesthesia induction. Core body temperatures and hemodynamic variables were monitored during and after operation. Post-anesthetic shivering (PAS) and pain scores were obtained in a post-anesthetic care unit. RESULTS: Intraoperative esophageal temperature changed significantly over time (P = 0.010), but significant intergroup difference in change was not observed (P = 0.706). Furthermore, shivering frequencies were similar in the two groups (P = 0.610). However, postoperative pain scores at 30 min after entering the post-anesthesia care unit were significantly lower in the palonosetron group (P = 0.002). DISCUSSION: Regardless of the previously reported anti-shivering effect of 5-HT3 receptor antagonists, pre-operative palonosetron 0.075 mg did not influence perioperative hypothermia or PAS in this study. This discrepancy might be due to the dose responsiveness of palonosetron to PAS and relatively low incidence of PAS in the elderly. CONCLUSIONS: Pre-operative administration of palonosetron 0.075 mg did not influence perioperative hypothermia or post-anesthesia shivering in elderly patients undergoing laparoscopic cholecystectomy. However, palonosetron might be beneficial for reducing early postoperative pain in elderly patients with opioid-based patient-controlled analgesia.

Effect of Preoperative Forced-Air Warming on Hypothermia in Elderly Patients Undergoing Transurethral Resection of the Prostate.

PURPOSE: Elderly patients under spinal anesthesia are vulnerable to hypothermia, leading to increased morbidity. The aim of this study was to investigate the effects of preoperative forced-air warming on perioperative hypothermia and shivering in elderly patients undergoing transurethral resection of the prostate (TURP) under spinal anesthesia. MATERIALS AND METHODS: Patients (> 65-year-old) scheduled for TURP under spinal anesthesia were randomly assigned to receive preoperative forced-air skin warming for 20 min (the pre-warmed group, n = 25) or not (control group, n = 25). Core temperatures were measured at 15-min intervals after spinal anesthesia, and intra- and post-operative shivering were also assessed. RESULTS: Incidences of intraoperative hypothermia (< 36 ºC) in the pre-warmed and control groups were not significantly different (10/25 [40%] vs. 15/24 [62.5%], P = .259). However, severities of hypothermia were significantly different (P = .019). No patient in the pre-warmed group showed moderate or profound hypothermia, whereas of patients in control group 21% and 13% did so, respectively. CONCLUSION: This study demonstrated that a brief period of preoperative forced-air warming did not completely prevent intraoperative hypothermia or shivering, but it could significantly reduce its severity in elderly male patients under spinal anesthesia.