Consciousness and General Anesthesia: Challenges for Measuring the Depth of Anesthesia.

The optimal consciousness level required for general anesthesia with surgery is unclear, but in existing practice, anesthetic oblivion, may be incomplete. This article discusses the concept of consciousness, how it is altered by anesthetics, the challenges for assessing consciousness, currently used technologies for assessing anesthesia levels, and future research directions. Wakefulness is marked by a subjective experience of existence (consciousness), perception of input from the body or the environment (connectedness), the ability for volitional responsiveness, and a sense of continuity in time. Anesthetic drugs may selectively impair some of these components without complete extinction of the subjective experience of existence. In agreement with Sanders et al. (2012), the authors propose that a state of disconnected consciousness is the optimal level of anesthesia, as it likely avoids both awareness and the possible dangers of oversedation. However, at present, there are no reliably tested indices that can discriminate between connected consciousness, disconnected consciousness, and complete unconsciousness.

Adoption of Ultrasound-guided Polymer Nanocarriers in Tumor Chemoradiotherapy and Oxidation Treatment.

The research was aimed at discussing the effectiveness of ultrasound-guided polymer nanocarriers in the clinical treatment of tumors by chemoradiotherapy and oxidation treatment. Twenty female Balb/cAnN (BALB/C) mice were selected as the research objects in the experiment. These mice were set up as tumor-bearing mice, and then ultrasound-guided polymers with different doses, including polyethylene glycol-poly 2-bromoethyl methacrylate (PEG-PBEMA) (Micelle group), free small molecules called l-ascorbyl palmitate (PA) (PA group), PA-micelle micellar particles (PA-Micelle group) prepared in the research, and phosphate buffer solution (PBS) (PBS group) were adopted. Besides, the growth of mice was recorded and compared after each operation. Meanwhile, different concentrations of PA-Micelle micellar particles and free small molecules of PA were added to the breast cancer cells of mice, and the concentration changes of glutathione (GSH) were detected to test the oxidation treatment ability of this method. According to the results of the experiment, the tumor volume of mice in the PA-Micelle group prepared in the research was the smallest followed by the PA group, and the tumor volume of mice in the Micelle group was the third smallest. The mice in the PBS group had the largest tumors among mice in all four groups. In oxidation treatment, the GSH concentration of mice in the PA-Micelle group was the lowest, while the GSH concentration of mice in the PA group was almost unchanged. The results of this experiment proved that the therapeutic effect of polymer nanocarriers in tumor chemotherapy and oxidation treatment was more significant than in traditional drug treatment.

Comparison of a simplified nasal continuous positive airways pressure device with nasal cannula in obese patients undergoing colonoscopy during deep sedation: A randomised clinical trial.

BACKGROUND: Continuous positive airways pressure (CPAP) with a CPAP machine and mask has been shown to be more effective at minimising hypoxaemia than other devices under deep sedation. However, the efficacy of a new and simple CPAP device for spontaneously breathing obese patients during colonoscopy is unknown. OBJECTIVE: We hypothesised that oxygenation and ventilation in obese patients under deep sedation during colonoscopy using CPAP via a new nasal mask (SuperNO2VA) would be better than routine care with oxygen supplementation via a nasal cannula. DESIGN: Randomised study. SETTING: Single-centre, June 2017 to October 2017. PATIENTS: A total of 174 patients were enrolled and randomly assigned to Mask group or Control group. Thirty-eight patients were excluded and data from 136 patients underwent final analysis. INTERVENTION: Patients in the Mask group were provided with nasal CPAP (10 cmH2O) at an oxygen flow rate of 15 l min. In the Control group, patients were given oxygen via a nasal cannula at a flow rate of 5 l min. MAIN OUTCOME MEASURES: The primary outcome was elapsed time from anaesthesia induction to the first airway intervention. RESULTS: The elapsed time from anaesthesia induction to the first airway intervention was 19 ±â€Š10 min in the Mask group (n=63) vs. 10 ±â€Š12 min in the Control group (n=73, P < 0.001). In all, 87.5% (56/64) of patients achieved the target CPAP value. More patients in the Control group (63%) received airway intervention than in the Mask group (22%) (P < 0.001). Hypoxaemia (pulse oximeter oxygen saturation, SpO2 < 90%) occurred more frequently in the Control group (22%) than in the Mask group (5%) (P = 0.004). Minute ventilationPostinduction/minute ventilationBaseline and minute ventilationProcedure-end/minute ventilationBaseline was lower in the Control group than in the Mask group (P = 0.007 and 0.001, respectively). CONCLUSION: Application of a nasal mask at a target CPAP of 10 cmH2O improves ventilation and decreases the frequency and severity of hypoxaemia. TRIAL REGISTRATION: NCT03139448, registered at ClinicalTrials.gov.

Endotracheal catheter equipped with functional cuff produces clinically relevant positive end expiratory pressure: a bench study.

Recently, we developed a novel endotracheal catheter with functional cuff (ECFC). Using such an ECFC and a regular ICU ventilator, we were able to generate clinically relevant tidal volume in a lung model and adult human sized animal. This ECFC allows co-axial ventilation without using a jet ventilator. The aim of this study was to determine if ECFC also could generate clinically relevant positive end expiratory pressure (PEEP). The experiment was conducted on a model lung and artificial trachea. Lung model respiratory mechanics were set to simulate those of an adult human being. The tip of the distal end of ECFC 14 or 19 Fr catheter was positioned in the artificial trachea 3 cm above the carina. The proximal end of ECFC was connected to an ordinary ICU ventilator. With 14 Fr catheter at respiratory rate 10 bpm, PEEP 0, 2.9, 8.2, 12.9 cmH2O was generated at preset PEEP 0, 5, 10, 15 cmH2O respectively and tidal volume was up to 393.4 ml. With 19 Fr catheter, PEEP was 0, 2.8, 7.6, 12.3 cmH2O, at preset PEEP 0, 5, 10, 15 cmH2O respectively and the tidal volume was up to 667.3 ml. With 14 Fr catheter at respiratory rate 20 bpm, PEEP was 0, 3.9, 9.6, 14.6 cmH2O at preset PEEP 0, 5, 10, 15 cmH2O respectively and tidal volume was up to 188.8 ml. With 19 Fr catheter, PEEP was 0, 3.6, 8.9, 13 cmH2O, at preset PEEP 0, 5, 10, 15 cmH2O respectively and tidal volume was up to 345.3 ml. ECFC enables clinicians to generate not only adequate tidal volume but also clinically relevant PEEP via co-axial ventilation using an ordinary ICU ventilator.

Buprenorphine Depresses Respiratory Variability in Obese Mice with Altered Leptin Signaling.

BACKGROUND: Opiate-induced respiratory depression is sexually dimorphic and associated with increased risk among the obese. The mechanisms underlying these associations are unknown. The present study evaluated the two-tailed hypothesis that sex, leptin status, and obesity modulate buprenorphine-induced changes in breathing. METHODS: Mice (n = 40 male and 40 female) comprising four congenic lines that differ in leptin signaling and body weight were injected with saline and buprenorphine (0.3 mg/kg). Whole-body plethysmography was used to quantify the effects on minute ventilation. The data were evaluated using three-way analysis of variance, regression, and Poincaré analyses. RESULTS: Relative to B6 mice with normal leptin, buprenorphine decreased minute ventilation in mice with diet-induced obesity (37.2%; P < 0.0001), ob/ob mice that lack leptin (62.6%; P < 0.0001), and db/db mice with dysfunctional leptin receptors (65.9%; P < 0.0001). Poincaré analyses showed that buprenorphine caused a significant (P < 0.0001) collapse in minute ventilation variability that was greatest in mice with leptin dysfunction. There was no significant effect of sex or body weight on minute ventilation. CONCLUSIONS: The results support the interpretation that leptin status but not body weight or sex contributed to the buprenorphine-induced decrease in minute ventilation. Poincaré plots illustrate that the buprenorphine-induced decrease in minute ventilation variability was greatest in mice with impaired leptin signaling. This is relevant because normal respiratory variability is essential for martialing a compensatory response to ventilatory challenges imposed by disease, obesity, and surgical stress.

A novel device for air removal from vascular access line: a bench study.

Efficient air removal from a vascular access line is a key step to prevent air embolism. Existing devices, especially for rapid infusers, are far from optimum. In this study, we developed a novel device, vascular access line air removal device (VALARD), and compared its efficiency of air removal and pause time of forward bulk flow with a commonly used device, the Belmont pump. Part I experiment, saline was infused at a forward bulk flow rate of 250, 500, and 750 mL/min. Meanwhile, air was introduced into the infusion line at a rate of 5, 10, and 15 mL/min for each bulk flow rate. Air bubbles > 10 µL downstream from either the VALARD or the Belmont pump and the fraction of pause time of the forward bulk flow were determined. Part II experiment, 120 mL of air was rapidly introduced into the VALARD at a bulk flow rate of about 500 mL/min. Air bubbles > 10 µL downstream from the VALARD, fraction of pause time of the forward bulk flow, and the transit time of the 120 mL of air at the working chamber were recorded. The VALARD: no air bubbles > 10 µL were detected during any tested combination of air injection and bulk flow rates without pause of forward flow. The Belmont pump: air bubbles > 10 µL were detected in 60% of the tests with pause of the forward flow. The VALARD eliminates air efficiently without pause of the forward bulk flow. Further clinical trials are needed to compare the VALARD with other devices and to assess its efficiency, safety, and user friendliness.

Anticipated and unanticipated difficult airway management.

PURPOSE OF REVIEW: Management of difficult airway is far from optimal despite of continuous progress in science and technology. The purpose of this review is to summarize the current research in the field and bring readers up to date. RECENT FINDINGS: New technologies for intubation make providers more confident to handle difficult airways, but there is lack of evidence indicating the reduction in incidence of 'cannot intubate cannot ventilate (CICV)'. Optimization of mask ventilation should reduce the incidence of difficult mask ventilation but it is greatly underappreciated. Even optimization of preoxygenation is not directly associated with any decreased incidence of difficult airway, but it prolongs time of safe apnea oxygenation; therefore, is likely to improve the outcome of the patients if CICV occurs. SUMMARY: Improvement of managing difficult airway relies on optimized mask ventilation, utilization of the appropriate tools for intubation, maximization of the safe apnea oxygenation time, prompt surgical airway in response to severe hypoxia in case effective noninvasive interventions are not achievable. It seems that a simplified and concise algorithm of difficult airway management needs to be established in order to enable providers to easily remember and execute.

The effect of head rotation on efficiency of face mask ventilation in anaesthetised apnoeic adults: A randomised, crossover study.

BACKGROUND: Upper airway obstruction occurs commonly after induction of general anaesthesia. It is the major cause of difficult mask ventilation. OBJECTIVES: The aim of this study was to determine whether head rotation improves the efficiency of mask ventilation of anaesthetised apnoeic adults. DESIGN: A randomised, crossover study. SETTING: Single university teaching hospital. PATIENTS: Forty patients, aged 18 to 75 years with a BMI 18.5 to 35.0 kg m requiring general anaesthesia for elective surgery were recruited and randomised into two groups. INTERVENTIONS: Once apnoeic after induction of general anaesthesia, face mask ventilation began with pressure controlled ventilation, at a peak inspiratory pressure of 15 cmH2O. Each patient was ventilated for three 1-min intervals with the head position alternated every minute: group A, mask ventilation was performed with a neutral head position for 1 min, followed by an axial head position rotated 45° to the right for 1 min and then returned to the neutral position for another 1 min. In group B, the sequence of head positioning was rotated → neutral → rotated. MAIN OUTCOME MEASURES: Expiratory tidal volume, measured with a respiratory inductive plethysmograph. RESULTS: Two patients were excluded due to protocol violation; thus, data from 38 patients were analysed. The mean expiratory tidal volume was significantly higher in the rotated head position than in the neutral position (612.6 vs. 544.0 ml: difference [95% confidence interval], 68.6 [46.8 to 90.4] ml, P < 0.0001). CONCLUSION: Head rotation of 45° in anaesthetised apnoeic adults significantly increases the efficiency of mask ventilation compared with the neutral head position. Head rotation is an effective alternative to improve mask ventilation if airway obstruction is encountered. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02755077.

Intravenous vs Oral Acetaminophen as an Adjunct to Multimodal Analgesia After Total Knee Arthroplasty: A Prospective, Randomized, Double-Blind Clinical Trial.

BACKGROUND: The efficacy of intravenous (IV) acetaminophen compared with its oral formulation for postoperative analgesia is unknown. We hypothesized that the addition of acetaminophen to a multimodal analgesia regimen would provide improved pain management in patients after total knee arthroplasty (TKA) and that the effect of acetaminophen would be variable based on the route of delivery. METHODS: The study was a single-center, randomized, double-blinded, placebo-controlled clinical trial on the efficacy of IV vs oral acetaminophen in patients undergoing unilateral TKA. One hundred seventy-four subjects were randomized to one of the 3 groups: IV acetaminophen group (IV group, n = 57) received 1 g IV acetaminophen and oral placebo before postanesthesia care unit (PACU) admission; oral acetaminophen group (PO group, n = 58) received 1 g oral acetaminophen and volume-matched IV normal saline; placebo group (Placebo group, n = 59) received oral placebo and volume-matched IV normal saline. Pain scores were obtained every 15 minutes during PACU stay. Average pain scores, maximum pain score, and pain scores before physical therapy were compared among the 3 groups. Secondary outcomes included total opiate consumption, time to PACU discharge, time to rescue analgesia, and time to breakthrough pain. RESULTS: The average PACU pain score was similar in the IV group (0.56 ± 0.99 [mean ± standard deviation]) compared with the PO group (0.67 ± 1.20; P = .84) and Placebo group (0.58 ± 0.99; P = .71). Total opiate consumption at 6 hours (0.47 mg hydromorphone equivalents ± 0.56 vs 0.54 ± 0.53 vs 0.54 ± 0.61; P = .69) and at 24 hours (1.25 ± 1.30 vs 1.49 ± 1.34 vs 1.36 ± 1.31; P = .46) were also similar between the IV, PO, and Placebo groups. No significant differences were found between all groups for any other outcome. CONCLUSION: Neither IV nor oral acetaminophen provides additional analgesia in the immediate postoperative period when administered as an adjunct to multimodal analgesia in patients undergoing TKA in the setting of a spinal anesthetic.

The effectiveness of nasal mask vs face mask ventilation in anesthetized, apneic pediatric subjects over 2 years of age: a randomized controlled trial.

BACKGROUND: We hypothesized that anesthetized, apneic children could be ventilated equivalently or more efficiently by nasal mask ventilation (NMV) than face mask ventilation (FMV). The aim of this randomized controlled study was to test this hypothesis by comparing the expiratory tidal volume (Vte) between NMV and FMV. METHODS: After the induction of anesthesia, 41 subjects, 3-17 years of age without anticipated difficult mask ventilation, were randomly assigned to receive either NMV or FMV with neck extension. Both groups were ventilated with pressure control ventilation (PCV) at 20 cmH2 O of peak inspiratory pressure (PIP) with positive end-expiratory pressure (PEEP) levels of 0, 5, and 10 cmH2 O. An additional mouth closing maneuver (MCM) was applied for the NMV group. RESULTS: The Vte was higher in the FMV group compared with the NMV group (median difference [95% CI]: 8.4 [5.5-11.6] ml·kg(-1) ; P < 0.001) when MCM was not applied. NMV achieved less PEEP than FMV (median difference [95% CI]: 5.0 [4.3-5.3] cmH2 O at 10 cmH2 O; P < 0.001) though both groups achieved the set PIP level. In the NMV group, MCM markedly increased Vte (median increase [95% CI]: 5.9 [2.5-9.0] ml·kg(-1) ; P < 0.005) and PEEP (median increase [95% CI]: 5.0 [0.6-8.6] cmH2 O at 10 cmH2 O; P < 0.005); however, PEEP was highly variable and lower than that of FMV (median difference [95% CI]: 2.5 [0.8-8.5] cmH2 O at 10 cmH2 O; P < 0.05). CONCLUSIONS: In anesthetized, apneic children greater than 2 years of age ventilated with an anesthesia ventilator and neck extension, FMV established a greater Vte than NMV regardless of mouth status. NMV could not maintain the set PEEP level due to an air leak from the mouth. The MCM increased the Vte and PEEP.

Efficacy of coaxial ventilation with a novel endotracheal catheter equipped with a functional cuff: A swine model study.

BACKGROUND: We have developed an endotracheal catheter with a functional cuff (ECFC) that inflates during inspiration and deflates during expiration. This catheter, together with a regular ICU ventilator, can provide coaxial ventilation. OBJECTIVE: The aim of this study was to determine the efficacy of ventilation in adult human-sized swine using an ECFC and a regular ICU ventilator. DESIGN: A prospective animal study. SETTING: Experimental, Trauma Transplant Surgery, Massachusetts General Hospital, Boston, Massachusetts, USA. ANIMALS: Eight adult Yorkshire swine, weighing 45 to 50  kg, were studied. INTERVENTIONS: To create the ECFC, a 5  cm long latex cuff was placed over the distal side ports of either a 14 or 19-Fr gauge endotracheal catheter and a 1  cm long piece of plastic tube was inserted into the tip of the endotracheal catheter to create an internal resistance. The ECFC was placed into the trachea and the proximal end of the ECFC was connected to an ICU ventilator in pressure-control mode, with peak pressures set at either 25, 50 or 70  cmH2O. MAIN OUTCOME MEASURES: Tidal volume was calculated using plethysmography. RESULTS: During pressure control ventilation with the 14-Fr gauge ECFC at set inspiratory pressures of 25, 50 and 75  cmH2O, the tidal volumes generated were 209 ±â€Š36, 309 ±â€Š61 and 367 ±â€Š85  ml, respectively, and with the 19-Fr gauge ECFC these were 277 ±â€Š51, 442 ±â€Š91 and 538 ±â€Š123  ml, respectively. No complications were observed. CONCLUSION: An ECFC combined with a regular pressure-controlled ICU ventilator can produce adequate tidal volumes in adult human-sized swine. Our results establish the feasibility of ventilation with this new alternative technique. The safety and advantages of such a technique remain to be determined in humans.

Construction and analysis of antennal cDNA library from rice striped stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), and expression profiles of putative odorant-binding protein and chemosensory protein genes.

In this study, we constructed a high-quality cDNA library from the antennae of the Chilo suppressalis (Walker) (Lepidoptera: Pyralidae). A total of 1,235 colonies with inserts greater than 0.7 kb were sequenced and analyzed. Homology searching coupled with bioinformatics analysis identified 15 and 7 cDNA sequences, respectively, encoding putative odorant-binding proteins (OBPs) and chemosensory proteins (CSPs). A phylogenetic tree of CsupCSPs showed that each CsupCSP has orthologs in Manduca sexta and Bombyx mori with strong bootstrapping support. One CSP was either very specific or more related to the CSPs of another species than to conspecific CSP. The expression profiles of the OBPs and CSPs in different tissues were measured by real-time quantitative PCR. The results revealed that of the 11 OBP genes, the transcript levels of CsupOBP1, CsupOBP5, and CsupOBP7 were higher in both male and female antennae than those in other tissues. And CsupCSP7 was highly expressed in both male and female antennae. Based on these results, the possible physiological functions of CsupOBPs and CsupCSPs were discussed.

Continuous measurement of cardiac output with the electrical velocimetry method in patients under spinal anesthesia for cesarean delivery.

In this study, we aimed to continuously measure cardiac output (CO) with the electrical velocimetry (EV) method and characterize the hemodynamic profile of patients undergoing spinal anesthesia for elective cesarean delivery (CD), and to discuss the potential benefit of using real time CO monitoring to guide patient management. Forty-two patients scheduled for elective CD under spinal anesthesia were enrolled in this observational study. A non-invasive CO monitor incorporating the electrical velocimetry algorithm, ICON(®) (Cardiotronic(®), La Jolla, California, USA), was used to measure CO and stroke volume (SV) continuously. Peripheral venous pressure was measured intermittently at pre-defined time points. Systemic vascular resistance was calculated retrospectively after completion of the study. Hemodynamic changes at pre-defined time points and caused by phenylephrine administration were analyzed. Hypotension (MAP reduction more than 20% from baseline values) occurred in 71.1% of patients after spinal anesthesia, while the coinstantaneous CO was increased ≥20% from baseline in the majority of patients (76.3%) at the same time. Significant increase in CO took place at 3-2 min before the administration of phenylephrine bolus. Treatment of hypotension with phenylephrine was associated with significant decrease in CO. Continuous CO monitoring with EV enables clinicians to determine CO and SV changes prior to onset of hypotension and to better understand patients' hemodynamics. It is an important addition to the current monitoring. The benefit of routinely using this technique remains to be determined in term of the patient outcomes.

Continuous positive airway pressure and ventilation are more effective with a nasal mask than a full face mask in unconscious subjects: a randomized controlled trial.

INTRODUCTION: Upper airway obstruction (UAO) is a major problem in unconscious subjects, making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye movement sleep. Continuous positive airway pressure (CPAP) via nasal mask is more effective at maintaining airway patency than a full face mask in patients with OSA. We hypothesized that CPAP via nasal mask and ventilation (nCPAP) would be more effective than full face mask CPAP and ventilation (FmCPAP) for unconscious subjects, and we tested our hypothesis during induction of general anesthesia for elective surgery. METHODS: In total, 73 adult subjects requiring general anesthesia were randomly assigned to one of four groups: nCPAP P0, nCPAP P5, FmCPAP P0, and FmCPAP P5, where P0 and P5 represent positive end-expiratory pressure (PEEP) 0 and 5 cm H2O applied prior to induction. After apnea, ventilation was initiated with pressure control ventilation at a peak inspiratory pressure over PEEP (PIP/PEEP) of 20/0, then 20/5, and finally 20/10 cm H2O, each applied for 1 min. At each pressure setting, expired tidal volume (Vte) was calculated by using a plethysmograph device. RESULTS: The rate of effective tidal volume (Vte > estimated anatomical dead space) was higher (87.9% vs. 21.9%; P<0.01) and the median Vte was larger (6.9 vs. 0 mL/kg; P<0.01) with nCPAP than with FmCPAP. Application of CPAP prior to induction of general anesthesia did not affect Vte in either approach (nCPAP pre- vs. post-; 7.9 vs. 5.8 mL/kg, P = 0.07) (FmCPAP pre- vs. post-; 0 vs. 0 mL/kg, P = 0.11). CONCLUSIONS: nCPAP produced more effective tidal volume than FmCPAP in unconscious subjects. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01524614.

Case report: profound hypotension after anesthetic induction with propofol in patients treated with rifampin.

Rifampin is commonly used for the treatment of tuberculosis and staphylococcal infections, as well as for prevention of infection in cardiac valve and bone surgeries. We report a case of profound hypotension after anesthesia induction with propofol in a patient who was treated with two 600 mg doses of rifampin for prophylaxis of infection before surgery. In a retrospective case-control study of 75 patients, we confirmed this potentially serious drug-drug interaction. After rifampin, there was a significant and prolonged arterial blood pressure reduction when patients received propofol, but not thiopental.