Comparison between general, spinal, epidural, and combined spinal-epidural anesthesia for cesarean delivery: a network meta-analysis.

BACKGROUND: This study is a network meta-analysis to compare maternal and fetal outcomes associated with four different anesthetic techniques for cesarean delivery. METHODS: An arm-based, random-effects frequentist network meta-analysis was performed. A random effect model was selected considering deviance information criteria. Randomized trials reporting the following outcomes were included: Apgar score at 1- or 5-min; umbilical arterial and venous pH; umbilical arterial pH <7.2; and neonatal score at 2-4 hours. Loop-specific heterogeneity was evaluated by risk of odds ratio and τ2. Quality of evidence was assessed using the GRADE approach. RESULTS: Data from 46 randomized trials including 3689 women contributed to the study. There were significant differences in Apgar score ≤6 at 1 min between spinal versus general anesthesia (odds ratio 0.27, 95% confidence interval [CI] 0.13 to 0.55: moderate quality evidence) and Apgar scores at 1- and 5-min, favoring spinal anesthesia. Umbilical venous pH associated with epidural anesthesia was significantly higher than that with general anesthesia (mean difference 0.010, 95% CI 0.001 to 0.020: moderate quality evidence) or spinal anesthesia. Spinal anesthesia was ranked best for Apgar score ≤6 at 1-min (SUCRA=89.8), Apgar score at 1-min (SUCRA=80.4) and 5-min (SUCRA=90.5). Epidural anesthesia was ranked highest for umbilical venous pH (SUCRA=87.4) and neonatal score (SUCRA=79.3). CONCLUSIONS: Spinal and epidural anesthesia were ranked high regarding Apgar scores and epidural anesthesia was ranked high regarding umbilical venous pH, but the results were based on small heterogeneous studies with high or unclear risks of bias.

Effect of prolonged inspiratory time on gas exchange during robot-assisted laparoscopic urologic surgery.

BACKGROUND: Gas exchange disturbance may develop during urologic robotic laparoscopic surgery with the patient in a steep Trendelenburg position. This study investigated whether prolonged inspiratory time could mitigate gas exchange disturbances including hypercapnia. METHODS: In this randomized cross-over trial, 32 patients scheduled for robot-assisted urologic surgery were randomized to receive an inspiratory to expiratory time ratio (I:E) of 1:1 for the first hour of pneumoperitoneum followed by 1:2 for last period of surgery (group A, n = 17) or I:E of 1:2 followed by 1:1 (group B, n = 15). Arterial blood gas analysis, airway pressure and hemodynamic variables were assessed at four time points (T1: 10 min after induction of general anesthesia, T2: 1 h after the initiation of pneumoperitoneum, T3: 1 h after T2 and T4: at skin closure). The carry over effect of initial I:E was also evaluated over the next hour through arterial blood gas analysis. RESULTS: There was a significant decrease in partial pressure of oxygen in arterial blood (PaO2) for both groups at T2 and T3 compared to T1 but in group B the PaO2 at T4 was not decreased from the baseline. Partial pressure of carbon dioxide in arterial blood (PaCO2) increased with I:E of 1:2 but did not significantly increase with I:E of 1:1; however, there were no differences in PaO2 and PaCO2 between the groups. CONCLUSION: Decreased oxygenation by pneumoperitoneum was improved and PaCO2 did not increase after 1 h of I:E of 1:1; however, the effect of equal ratio ventilation longer than 1 h remains to be determined. There was no carryover effect of the two different I:E ratios.

Pharmacological interventions for protecting renal function after cardiac surgery: a Bayesian network meta-analysis of comparative effectiveness.

Many drugs have been investigated as potentially protective of renal function after cardiac surgery. However, their comparative effectiveness has not been established. We performed an arm-based hierarchical Bayesian network meta-analysis including 95 randomised controlled trials with 28,833 participants, which allowed us to compare some agents not previously compared directly. Renal outcomes, including: the incidence of postoperative renal dysfunction and haemodialysis; serum creatinine level at 24 hours postoperatively; all-cause mortality; and length of hospital and ICU stay, were compared. Exploratory meta-regression was conducted for potential effect modifiers. A random effects model was selected according to the evaluation of model fit by deviance information criteria. Atrial natriuretic peptide (odds ratio (95%CrI) 0.28 (0.17-0.48); moderate-quality evidence), B-type natriuretic peptide, dexmedetomidine, levosimendan and N-acetyl cysteine significantly decreased the rate of postoperative renal dysfunction compared with placebo. Atrial natriuretic peptide (OR (95%CrI) 0.24 (0.10-0.58); low-quality evidence), B-type natriuretic peptide, and dexamethasone significantly decreased the need for haemodialysis. Levosimendan significantly decreased mortality, OR (95%CrI) 0.49 (0.27-0.91); low-quality evidence). The benefit of atrial natriuretic peptide was still apparent when baseline renal function was normal. None of the potential effect modifiers were significantly correlated with our renal outcomes. Atrial natriuretic peptide was ranked best regarding renal dysfunction, haemodialysis and length of hospital stay. Levosimendan was ranked best regarding mortality and ICU stay. However, our results should be interpreted cautiously given the assumptions made about transitivity and consistency.

Randomised trial comparing forced-air warming to the upper or lower body to prevent hypothermia during thoracoscopic surgery in the lateral decubitus position.

BACKGROUND: In the supine position, forced-air warming is more effective on the lower body than on the upper body to prevent intraoperative hypothermia. However, it is unknown in the lateral decubitus position. We thus compared forced-air warming on the upper and lower bodies in the lateral position. METHODS: Patients (n=123) were randomised to receive forced-air warming on the upper body or lower body during thoracoscopic surgery in the lateral position. We measured the nasopharyngeal temperature at 0, 30, 60, 90, and 120 min after lateral positioning during surgery and the infrared tympanic membrane temperature at 0, 30, 60, 90, and 120 min after surgery. Patients received both upper and lower body warming at a temperature of <35.5°C. The primary outcome was the incidence of intraoperative hypothermia with a temperature of <36.0°C. RESULTS: Intraoperative hypothermia was less frequent with the upper body warming than with the lower body warming {21/62 vs 35/61, risk ratio [95% confidence interval (CI)] 0.6 (0.4-0.9), P=0.011}. The intraoperative temperature was higher with the upper body warming than with the lower body warming at 30 (P=0.002), 60 (P<0.001), and 90 (P<0.001) min after lateral positioning, and the postoperative temperature was higher at 0 (P<0.001) and 30 (P=0.001) min after surgery. Fewer patients received both upper and lower body warming in the upper body warming group than in the lower body warming group during surgery (1 vs 7, P=0.032). CONCLUSIONS: Forced-air warming was more effective on the upper body than on the lower body to prevent hypothermia during thoracoscopic surgery in the lateral decubitus position. CLINICAL TRIAL REGISTRATION: NCT02993666.

Calling the patient's own name facilitates recovery from general anaesthesia: a randomised double-blind trial.

People can hear and pay attention to familiar terms such as their own name better than general terms, referred to as the cocktail party effect. We performed a prospective, randomised, double-blind trial to investigate whether calling the patient's name compared with a general term facilitated a patient's response and recovery from general anaesthesia. We enrolled women having breast cancer surgery with general anaesthesia using propofol and remifentanil. Patients were randomly allocated into two groups depending on whether the patient's name or a general term was called, followed by the verbal command - 'open your eyes!' - during emergence from anaesthesia; this pre-recorded sentence was played to the patient using headphones. Fifty patients were allocated to the name group and 51 to the control group. Our primary outcome was the time from discontinuation of anaesthesia until eye opening. The mean (SD) time was 337 (154) s in the name group and 404 (170) s in the control group (p = 0.041). The time to i-gel® removal was 385 (152) vs. 454 (173) s (p = 0.036), the time until achieving a bispectral index of 60 was 174 (133) vs. 205 (160) s (p = 0.3), and the length of stay in the postanaesthesia care unit was 43.8 (3.4) vs. 47.3 (7.1) min (p = 0.005), respectively. In conclusion, using the patient's name may be an easy and effective method to facilitate recovery from general anaesthesia.

The effects of thermal softening of double-lumen endobronchial tubes on postoperative sore throat, hoarseness and vocal cord injuries: a prospective double-blind randomized trial.

BACKGROUND: It is well known that thermal softening of polyvinyl chloride tracheal tubes reduces nasal damage during nasotracheal intubation. We hypothesized that thermal softening of double-lumen endobronchial tubes (DLTs) may be effective for reducing airway injury. This randomized double-blind study was performed to investigate whether thermal softening of DLTs decreased postoperative sore throat, hoarseness or vocal cord injuries. METHODS: Patients (n=140) undergoing one lung anaesthesia were randomized into two groups (n=70 each) depending on whether the DLT was softened by warming or not before tracheal intubation. The DLTs were placed in warm saline [40(1)°C] in the thermal softening group or in room temperature saline in the control group for 10 min. The vocal cords were examined by using flexible laryngoscopy immediately after extubation. Sore throat and hoarseness were evaluated for three postoperative days. The primary outcomes were the incidence of sore throat, hoarseness, and vocal cord injuries. RESULTS: Sore throat and vocal cord injuries occurred less frequently in the thermal softening group than in the control group [14/70 vs 27/70, risk ratio (95% CI): 0.52 (0.30-0.90), P=0.025 for sore throat; 15/70 vs 27/70, risk ratio (95% CI): 0.56 (0.32-0.95), P=0.042 for vocal cord injuries]. However, the incidence of hoarseness was comparable between the two groups. CONCLUSION: Tracheal intubation with DLTs softened by warming decreased the postoperative incidence of sore throat and vocal cord injuries. Therefore, thermal softening of DLTs before intubation seems to be helpful in reducing airway injuries associated with DLT intubation. CLINICAL TRIAL REGISTRATION: NCT 01626365.

Characterization of the temperature dependence of the thermoreflectance coefficient for conductive thin films.

We describe a novel approach for calibration of the thermoreflectance coefficient, ideally suited for measurements in a vacuum thermostat, and present the high temperature thermoreflectance coefficients for several metals commonly encountered in electronic devices: gold, platinum, and aluminum. The effect of passivation on these metals is also examined, and we demonstrate the signal to noise ratio of a thermoreflectance measurement can be improved with informed selection of the dielectric layer thickness. Furthermore, the thermo-optic coefficients of the metals are extracted over a wide temperature range. The results presented here can be utilized in the optimization of experimental configurations for high temperature thermoreflectance imaging.

A randomised controlled trial comparing incentive spirometry with the Acapella® device for physiotherapy after thoracoscopic lung resection surgery.

Lung resection surgery has been associated with numerous postoperative complications. Seventy-eight patients scheduled for elective video-assisted thoracoscopic lung resection were randomly assigned to receive standard postoperative care with incentive spirometry or standard care plus positive vibratory expiratory pressure treatment using the Acapella(®) device. There was no significant difference between incentive spirometry and the Acapella device in the primary outcome, forced expiratory volume in 1 s, on the third postoperative day, mean (SD) 53% (16%) vs 59% (18%) respectively, p = 0.113. Patients treated with both devices simultaneously found incentive spirometry to be less comfortable compared with the Acapella device, using a numeric rating scale from 1 to 5 with lower scores indicating higher comfort, median (IQR [range]) 3 (2-3 [2-4]) vs 1 (1-2 [1-3]) respectively, p < 0.001. In addition, 37/39 patients (95%) stated a clear preference for the Acapella device. Postoperative treatment with the Acapella device did not improve pulmonary function after thoracoscopic lung resection surgery compared with incentive spirometry, but it may be more comfortable to use.

Pulse pressure variation to predict fluid responsiveness in spontaneously breathing patients: tidal vs. forced inspiratory breathing.

We evaluated whether pulse pressure variation can predict fluid responsiveness in spontaneously breathing patients. Fifty-nine elective thoracic surgical patients were studied before induction of general anaesthesia. After volume expansion with hydroxyethyl starch 6 ml.kg(-1) , patients were defined as responders by a ≥ 15% increase in the cardiac index. Haemodynamic variables were measured before and after volume expansion and pulse pressure variations were calculated during tidal breathing and during forced inspiratory breathing. Median (IQR [range]) pulse pressure variation during forced inspiratory breathing was significantly higher in responders (n = 29) than in non-responders (n = 30) before volume expansion (18.2 (IQR 14.7-18.2 [9.3-31.3])% vs. 10.1 (IQR 8.3-12.6 [4.8-21.1])%, respectively, p < 0.001). The receiver-operating characteristic curve revealed that pulse pressure variation during forced inspiratory breathing could predict fluid responsiveness (area under the curve 0.910, p < 0.0001). Pulse pressure variation measured during forced inspiratory breathing can be used to guide fluid management in spontaneously breathing patients.

Comparison of techniques for double-lumen endobronchial intubation: 90° or 180° rotation during advancement through the glottis.

BACKGROUND: During endobronchial intubation with a double-lumen endobronchial tube (DLT), the DLT is conventionally rotated through 90° when the bronchial tip is just past the vocal cords. This study was performed to investigate if rotation of the DLT through 180° decreases postoperative hoarseness, sore throat, or vocal cord injuries. METHODS: Patients (n=164) undergoing thoracic surgery were randomized into two groups. Just after the bronchial tip passed the glottis, left-sided DLTs were rotated 90° (Group 90, n=84) or 180° (Group 180, n=80) counterclockwise and advanced. In the Group 180, DLTs were re-rotated 90° clockwise after the tracheal tip passed the glottis. Resistance during the advance of DLTs was assessed. Hoarseness and sore throat were evaluated for three postoperative days. Vocal cords were examined on the first postoperative day. RESULTS: In nine patients allocated to Group 90, the DLT could not be advanced past the glottis because of severe resistance. There was less resistance to advancement of the DLT in Group 180 compared with Group 90 (P<0.001). The incidence of hoarseness was comparable between the two groups. Sore throat and vocal cord injuries occurred less frequently in Group 180 compared with Group 90 (20 vs 40%, P=0.008; 19 vs 47%, P=0.032). CONCLUSIONS: Rotation of a DLT through 180° facilitated its passage through the glottis and reduced the incidence of postoperative sore throat and vocal cord injuries.

A novel maneuver to blindly position bronchial blockers.

BACKGROUND: The use of a fiberoptic bronchoscope is fundamental to the positioning of bronchial blockers. However, a fiberoptic bronchoscope could be unavailable. We tried to devise a blind method to locate the blocker without help of a fiberoptic bronchoscope. METHODS: In 56 thoracic surgical patients requiring one-lung ventilation, a Uniblocker® was inserted into the endotracheal tube and advanced until the blocker balloon just protruded from the endotracheal tube tip. With inflation of the balloon, peak inspiratory pressure increased abruptly with disappearance of expiratory tidal volume. The blocker was advanced with its tip directed to one side until peak inspiratory pressure abruptly dropped and expiratory tidal volume re-appeared. Thereafter, the blocker was advanced 3 cm further with the cuff deflated. Using a fiberoptic bronchoscope, the position of the blocker was checked after re-inflation of the cuff. The entire procedure was repeated on the other side. RESULTS: Acceptable blocker placements were achieved on 48 of 56 (85.7%) right attempts; the right upper bronchus was not blocked in 5 cases and blocker positions were too shallow in 3. Only 33 of 56 (58.9%) left attempts were acceptable in that blockers could not be advanced into the left bronchus in 19 and were positioned too shallow in 4. CONCLUSION: This novel technique to blindly position bronchial blockers could be almost successful in isolating the right lung. However, isolation of the left lung was frequently unsuccessful in spite of several attempts.

Comparison of the neutral and retracted shoulder positions for infraclavicular subclavian venous catheterization: a randomized, non-inferiority trial.

BACKGROUND: There are controversies regarding the most efficient shoulder position during infraclavicular subclavian venous catheterization. We hypothesized that, regarding the success rate of subclavian venous catheterization, the neutral shoulder position would not be inferior to the retracted shoulder position. METHODS: A total of 362 patients who underwent elective surgery were randomly assigned to two groups: those who underwent subclavian venous catheterizations in the neutral shoulder position (neutral group, n=181) or in the retracted shoulder position (retracted group, n=181). In the retracted group, a 1 litre saline bag was placed longitudinally beneath the spinal column between the scapulae to allow the shoulders to fall into a 'retracted' position. The incidence of failures to place the central venous catheters and complications such as arterial puncture, pneumothorax, or haemothorax were recorded. RESULTS: The success rates were 95.6% (173/181) in the neutral group and 96.1% (174/181) in the retracted group. The difference of 0.5% was within the prespecified non-inferiority margin of 5% with a P-value of 0.017 [two-sided 95% confidence interval (CI), -0.036 to 0.047; upper limit of the 95% CI, 0.040]. There were four catheterization failures (2.2%) in the neutral group and two failures (1.1%) in the retracted group. Complication rates were not significantly different between the neutral and retracted groups [3/181 (1.7%) vs 4/181 (2.2%) for arterial punctures and 1/181 (0.6%) vs 1/181 (0.6%) for pneumothorax]. CONCLUSIONS: The neutral shoulder position was as effective as the retracted shoulder position for infraclavicular subclavian venous catheterization. Shoulder retraction does not appear to be necessary for the infraclavicular subclavian venous catheterization. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT01368692.

An apparatus for simultaneous measurement of electrical conductivity and thermopower of thin films in the temperature range of 300-750 K.

An automated apparatus capable of measuring the electrical conductivity and thermopower of thin films over a temperature range of 300-750 K is reported. A standard dc resistance measurement in van der Pauw geometry was used to evaluate the electrical conductivity, and the thermopower was measured using the differential method. The design of the instrument, the methods used for calibration, and the measurement procedure are described in detail. Given the lack of a standard National Institute of Standards and Technology (Gaithersburg, Md.) sample for high temperature thermopower calibration, the disclosed calibration procedure shall be useful for calibration of new instruments.

Influence of shoulder position on central venous catheter tip location during infraclavicular subclavian approach.

BACKGROUND: Infraclavicular approach of the subclavian veins is commonly used for central venous access. However, aberrant catheter tip locations are frequently quoted for this approach. It was hypothesized that with the shoulder pulled downwards, the angle between the internal jugular and subclavian veins may increase, directing subclavian catheters into the internal jugular vein. This prospective study assessed the influence of the shoulder position on proper placement of right infraclavicular subclavian catheters. METHODS: Patients who required subclavian central venous catheterization for major neurosurgical and thoracic procedures were randomly divided into two groups: neutral (n=180) vs lowered (n=181) shoulder position. The right shoulder was placed and maintained in the neutral or lowered position during venipuncture and guidewire insertion. Postoperative chest radiographs were obtained to identify the location of catheter tips. RESULTS: There were no differences in gender, age, body weight, and height between the two groups. There were five failures in the neutral position [5/180 (2.8%)] and eight failures in the lowered shoulder position [8/181 (4.0%)] (P=NS). The occurrence of immediate complications such as pneumothorax or arterial puncture was not different. Aberrant placement of the catheter tips was more frequent in the lowered shoulder position [2/173 (1.2%) vs 14/173 (8.1%)] (P<0.01). CONCLUSIONS: The neutral shoulder position minimizes the number of needle passes and the incidence of catheter misplacement during the infraclavicular approach of the right subclavian vein catheterization.

The effect of remote ischaemic preconditioning on myocardial injury in patients undergoing off-pump coronary artery bypass graft surgery.

In several recent clinical trials on cardiac surgery patients, remote ischaemic preconditioning (RIPC) showed a powerful myocardial protective effect. However the effect of RIPC has not been studied in patients undergoing off-pump coronary artery bypass graft surgery. We evaluated whether RIPC could induce myocardial protection in off-pump coronary artery bypass graft surgery patients. Patients undergoing elective off-pump coronary artery bypass graft surgery were randomly allocated to the RIPC (n = 65) or control group (n = 65). After induction of anaesthesia, RIPC was induced by four cycles of five-minute ischaemia and reperfusion on the upper limb using a pneumatic cuff. Anaesthesia was maintained with sevoflurane, remifentanil and vecuronium. Myocardial injury was assessed by troponin I before surgery and 1, 6, 12, 24, 48 and 72 hours after surgery. There were no statistical differences in troponin I levels between RIPC and control groups (P = 0.172). Although RIPC reduced the total amount of troponin I (area under the curve of troponin increase) by 26%, it did not reach statistical significance (RIPC group 53.2 +/- 72.9 hours x ng/ml vs control group 67.4 +/- 97.7 hours x ng/ml, P = 0.281). In this study, RIPC by upper limb ischaemia reduced the postoperative myocardial enzyme elevation in off-pump coronary artery bypass graft surgery patients, but this did not reach statistical significance. Further study with a larger number of patients may be needed to fully evaluate the clinical effect of RIPC in off-pump coronary artery bypass graft surgery patients.